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Sample records for cementitious repair mortars

  1. Durability of Polymer Modified Repair Mortars on Concrete Structures

    OpenAIRE

    TCHETGNIA NGASSAM, Inès-Léana; Marceau, Sandrine; Chaussadent, Thierry

    2013-01-01

    Polymer modified mortars (PMM) used as repair products present higher intrinsic properties than classic mortar due to polymer effect in the cementitious matrix. But evolution of their adhesives properties is not well known. This article deals with adhesive behavior of two PMMs made in laboratory with styrene acrylate (SA) and ethylene vinyl acetate (EVA) polymers. It is highlighted that adhesion of these mortars depends on polymer amount in the mortar, on the environmental conditions, and on...

  2. Compatibility of repair mortars in restoration projects

    OpenAIRE

    Schueremans, Luc; Van Balen, Koenraad; Cizer, Özlem; Janssens, Elke; Serré, Gerty; Elsen, Jan; Brosens, Kris; Ignoul, Sven

    2010-01-01

    Mortars used for restoration must be highly compatible with historic materials in terms of physical, chemical and mechanical properties in order to assure the durability of masonry on the long term. Compatibility criteria are defined based on the original mortar characteristics but the efficiency and the performance of the repair mortar after application on masonry are not generally evaluated. From this perspective, historic mortars and repair mortars from 3 historic masonry structures were a...

  3. Mechanical resilience and cementitious processes in Imperial Roman architectural mortar.

    Science.gov (United States)

    Jackson, Marie D; Landis, Eric N; Brune, Philip F; Vitti, Massimo; Chen, Heng; Li, Qinfei; Kunz, Martin; Wenk, Hans-Rudolf; Monteiro, Paulo J M; Ingraffea, Anthony R

    2014-12-30

    The pyroclastic aggregate concrete of Trajan's Markets (110 CE), now Museo Fori Imperiali in Rome, has absorbed energy from seismic ground shaking and long-term foundation settlement for nearly two millenia while remaining largely intact at the structural scale. The scientific basis of this exceptional service record is explored through computed tomography of fracture surfaces and synchroton X-ray microdiffraction analyses of a reproduction of the standardized hydrated lime-volcanic ash mortar that binds decimeter-sized tuff and brick aggregate in the conglomeratic concrete. The mortar reproduction gains fracture toughness over 180 d through progressive coalescence of calcium-aluminum-silicate-hydrate (C-A-S-H) cementing binder with Ca/(Si+Al) ≈ 0.8-0.9 and crystallization of strätlingite and siliceous hydrogarnet (katoite) at ≥ 90 d, after pozzolanic consumption of hydrated lime was complete. Platey strätlingite crystals toughen interfacial zones along scoria perimeters and impede macroscale propagation of crack segments. In the 1,900-y-old mortar, C-A-S-H has low Ca/(Si+Al) ≈ 0.45-0.75. Dense clusters of 2- to 30-µm strätlingite plates further reinforce interfacial zones, the weakest link of modern cement-based concrete, and the cementitious matrix. These crystals formed during long-term autogeneous reaction of dissolved calcite from lime and the alkali-rich scoriae groundmass, clay mineral (halloysite), and zeolite (phillipsite and chabazite) surface textures from the Pozzolane Rosse pyroclastic flow, erupted from the nearby Alban Hills volcano. The clast-supported conglomeratic fabric of the concrete presents further resistance to fracture propagation at the structural scale. PMID:25512521

  4. Mechanical resilience and cementitious processes in Imperial Roman architectural mortar

    Science.gov (United States)

    Landis, Eric N.; Brune, Philip F.; Vitti, Massimo; Chen, Heng; Li, Qinfei; Kunz, Martin; Wenk, Hans-Rudolf; Monteiro, Paulo J. M.; Ingraffea, Anthony R.

    2014-01-01

    The pyroclastic aggregate concrete of Trajan’s Markets (110 CE), now Museo Fori Imperiali in Rome, has absorbed energy from seismic ground shaking and long-term foundation settlement for nearly two millenia while remaining largely intact at the structural scale. The scientific basis of this exceptional service record is explored through computed tomography of fracture surfaces and synchroton X-ray microdiffraction analyses of a reproduction of the standardized hydrated lime–volcanic ash mortar that binds decimeter-sized tuff and brick aggregate in the conglomeratic concrete. The mortar reproduction gains fracture toughness over 180 d through progressive coalescence of calcium–aluminum-silicate–hydrate (C-A-S-H) cementing binder with Ca/(Si+Al) ≈ 0.8–0.9 and crystallization of strätlingite and siliceous hydrogarnet (katoite) at ≥90 d, after pozzolanic consumption of hydrated lime was complete. Platey strätlingite crystals toughen interfacial zones along scoria perimeters and impede macroscale propagation of crack segments. In the 1,900-y-old mortar, C-A-S-H has low Ca/(Si+Al) ≈ 0.45–0.75. Dense clusters of 2- to 30-µm strätlingite plates further reinforce interfacial zones, the weakest link of modern cement-based concrete, and the cementitious matrix. These crystals formed during long-term autogeneous reaction of dissolved calcite from lime and the alkali-rich scoriae groundmass, clay mineral (halloysite), and zeolite (phillipsite and chabazite) surface textures from the Pozzolane Rosse pyroclastic flow, erupted from the nearby Alban Hills volcano. The clast-supported conglomeratic fabric of the concrete presents further resistance to fracture propagation at the structural scale. PMID:25512521

  5. Use of polypropylene fibers coated with nano-silica particles into a cementitious mortar

    International Nuclear Information System (INIS)

    Fiber reinforced cementitious composite (FRCC) materials have been widely used during last decades in order to overcome some of traditional cementitious materials issues: brittle behaviour, fire resistance, cover spalling, impact strength. For composite materials, fiber/matrix bond plays an important role because by increasing fiber/matrix interactions is possible to increase the behaviour of the entire material. In this study, in order to improve fiber to matrix adhesion, two chemical treatments of polypropylene fibers were investigated: alkaline hydrolysis and nano-silica sol-gel particles deposition. Treatmtents effect on fibers morphology and mechanical properties was investigated by scanning electron microscopy (SEM) and tensile tests. SEM investigations report the presence of spherical nano-silica particles on fiber surface, in the case of sol-gel process, while alkaline hydrolysis leads to an increase of fibers roughness. Both treatments have negligible influence on fibers mechanical properties confirming the possibility of their use in a cementitious mortar. Pullout tests were carried out considering three embedded length of fibers in mortar samples (10, 20 and 30 mm, respectively) showing an increase of pullout energy for treated fibers. The influence on fiber reinforced mortar mechanical properties was investigated by three-point flexural tests on prismatic specimens considering two fibers length (15 and 30 mm) and two fibers volume fractions (0.50 and 1.00 %). A general increase of flexural strength over the reference mix was achieved and an overall better behaviour is recognizable for mortars containing treated fibers

  6. Use of polypropylene fibers coated with nano-silica particles into a cementitious mortar

    Science.gov (United States)

    Coppola, B.; Di Maio, L.; Scarfato, P.; Incarnato, L.

    2015-12-01

    Fiber reinforced cementitious composite (FRCC) materials have been widely used during last decades in order to overcome some of traditional cementitious materials issues: brittle behaviour, fire resistance, cover spalling, impact strength. For composite materials, fiber/matrix bond plays an important role because by increasing fiber/matrix interactions is possible to increase the behaviour of the entire material. In this study, in order to improve fiber to matrix adhesion, two chemical treatments of polypropylene fibers were investigated: alkaline hydrolysis and nano-silica sol-gel particles deposition. Treatmtents effect on fibers morphology and mechanical properties was investigated by scanning electron microscopy (SEM) and tensile tests. SEM investigations report the presence of spherical nano-silica particles on fiber surface, in the case of sol-gel process, while alkaline hydrolysis leads to an increase of fibers roughness. Both treatments have negligible influence on fibers mechanical properties confirming the possibility of their use in a cementitious mortar. Pullout tests were carried out considering three embedded length of fibers in mortar samples (10, 20 and 30 mm, respectively) showing an increase of pullout energy for treated fibers. The influence on fiber reinforced mortar mechanical properties was investigated by three-point flexural tests on prismatic specimens considering two fibers length (15 and 30 mm) and two fibers volume fractions (0.50 and 1.00 %). A general increase of flexural strength over the reference mix was achieved and an overall better behaviour is recognizable for mortars containing treated fibers.

  7. MORTAR INCORPORATING SUPPLEMENTARY CEMENTITIOUS MATERIALS: STRENGTH, ISOTHERMAL CALORIMETRY AND ACIDS ATTACK

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    Y. Senhadji

    2016-05-01

    Full Text Available Supplementary cementitious materials (SCMs prove to be effective to meet most of the requirements of durable concrete and leads to a significant reduction in CO2 emissions. This research studies the effect different SCMs (natural pozzolan (PN/ limestone fine (FC at various remplacement levels on the physical and mechano-chemical resistance of blended mortar. The paper primarily deals with the characteristics of these materials, including heat of hydration, strength and effects of aggressive chemical environments (using sulphuric acid and nitric acid. Over 6 mixes were made and compared to the control mix. Tests were conducted at different ages up to 360 days. The experimental results in general showed that Algerian mineral admixtures (PN/FC were less vulnerable to nitric and sulphuric acid attack and improved the properties of mortars, but at different rates depending on the quantity of binder.

  8. Performance and repair requirements for flooring mortars

    Czech Academy of Sciences Publication Activity Database

    Válek, Jan; Groot, C.; Hughes, J.J.

    Cachan Cedex : RILEM Publications S.A.R.L, 2010, s. 1365-1376 ISBN 978-2-35158-112-4. [Historic mortars conference HMC2010 /2./ and RILEM TC 203-RHM Final Workshop. Prague (CZ), 22.09.2010-24.09.2010] R&D Projects: GA MŠk(CZ) LA09008 Institutional research plan: CEZ:AV0Z20710524 Keywords : masonry * mortar properties * technical requirements Subject RIV: JN - Civil Engineering

  9. Mechanism and Durability of Repair Systems in Polymer-Modified Cement Mortars

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    Ru Wang

    2015-01-01

    Full Text Available This paper investigated the mechanism and durability of repair systems made of ordinary cement-based repair mortar and three kinds of polymer-modified repair mortars with old concrete, SBR dispersion, SAE dispersion, and SAE powder. By comparing the bonding properties of mortars before and after erosion, it was found that polymers could effectively improve the durability of the repair system and SAE powder had the best improvement. Micromorphology study of the repair mortar and the interface of repair mortar with old concrete through SEM showed that the polymer film formed from SAE powder whatever in the mortar or at the interface was dense and tough, the film formed from SAE dispersion was loose and weak, while the film formed from SBR dispersion was in between them, which explained the difference in the tensile bond strength and the durability of the repair systems.

  10. Historic mortars: Characterisation, assessment and repair. A state-of-the-art summary

    Czech Academy of Sciences Publication Activity Database

    Válek, Jan; Hughes, J.J.; Groot, C.

    Vol. 7. Dordrecht : Springer, 2012 - (Válek, J.; Hughes, J.; Groot, J.), s. 1-12 ISBN 978-94-007-4634-3 R&D Projects: GA MŠk(CZ) LA09008 Institutional support: RVO:68378297 Keywords : historic mortars * 2nd Historic mortars conference 2010, Prague * repair mortars Subject RIV: AL - Art, Architecture, Cultural Heritage

  11. Detachment analysis of dehumidified repair mortars applied to historical masonry walls

    OpenAIRE

    Bocca, Pietro Giovanni; Valente, Silvio; Grazzini, Alessandro; Alberto, Andrea

    2014-01-01

    An innovative laboratory procedure for the pre-qualification of repair mortars is described. The tested mortars are suitable for use with new dehumidified plasters applied to historical masonry walls. Long-term plaster detachment frequently occurs because of the mechanical incompatibility of mortar. The procedure consists of the application of static loads to mixed stone block-mortar specimens with particular characteristics, in terms of geometry and adhesion at the interface. A numerical sim...

  12. The compatibility of earth-based repair mortars with rammed earth substrates

    OpenAIRE

    Gomes, M. Idália; Gonçalves, Teresa D.; Faria, Paulina

    2013-01-01

    Earth constructions are susceptible to degradation due to natural or human causes. The degradation of the exterior surface of earth walls is very common, either due to lack of maintenance or to the use of incompatible materials, and often requires the application of a repair mortar. This work analyses experimentally the performance of earth-based repair mortars applied on rammed earth surfaces. The mortars are based on earth collected from rammed earth buildings in south Portugal or on a c...

  13. Improvement of adhesion performance of mortar-repair interface with inducing crack path into repair

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    A. Satoh

    2015-10-01

    Full Text Available The most important performance for repair materials is adhesion to the substrate. The authors experimentally find out that high modulus fine aggregates in repair material enhance strength of it as well as the strength of the interface repaired with it, compared to the ordinary repair without fine aggregates. This paper elaborates the mechanisms for that with fractographic observation and FEM analysis based on the results of experiment. Also the authors discuss the ways for enhancing the strength and ductility of the repaired mortar

  14. RILEM TC 203-RHM: Repair mortars for historic masonry Repair mortars for historic masonry. From problem to intervention: a decision process

    Czech Academy of Sciences Publication Activity Database

    Groot, C.; van Balen, K.; Bicer-Simsir, B.; Binda, L.; Elsen, J.; van Hees, R.; von Konow, T.; Lindqvist, J.; Mauerbrecher, P.; Papayanni, I.; Subercaseaux, M.; Tedeschi, C.; Toumbakari, E.; Thompson, M.; Válek, Jan; Veiga, R.

    2012-01-01

    Roč. 45, č. 9 (2012), s. 1295-1302. ISSN 1359-5997 Institutional support: RVO:68378297 Keywords : mortars * repair * intervention Subject RIV: JN - Civil Engineering Impact factor: 1.184, year: 2012

  15. Influence of supplementary cementitious materials on water transport kinetics and mechanical properties of hydrated lime and cement mortars

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    Ince, C.

    2015-06-01

    Full Text Available The purpose of this paper is an investigation of the possible role of supplementary cementitious materials (SCMs on water transport kinetics and mechanical properties of hydrated lime (CL90 and Portland cement (PC mortars. The properties of hydrated lime are significantly different from those of cement and therefore modifying fresh and hardened properties of these mortars are vital for mortar/substrate optimisation in masonry construction. The parameters investigated in this paper often are the main barriers to the use of hydrated lime in construction practice. The results show that transfer sorptivity and time to dewater freshly-mixed hydrated lime mortars can be modified when binder is partially replaced with SCMs. Compressive strength of CL90 mortars is increased systematically with the increased replacement levels of SCMs and the results are supported with the microstructural images. The ability to modify the water transport kinetics and mechanical properties allows compatibility between the mortar and the substrate unit in masonry construction.El objetivo de este artículo es investigar el papel de los materiales cementantes suplementarios (SCMs en la cinética de transporte del agua y en las propiedades mecánicas de los morteros de cal hidratada (CL90 y cemento Portland. Las propiedades de la cal hidratada son significativamente diferentes a las del cemento y por lo tanto el control de las propiedades de los morteros frescos y endurecidos es fundamental en la optimización mortero/substrato en albañilería. Los parámetros estudiados en este trabajo son a menudo las principales barreras para el uso de la cal hidratada en la práctica de la construcción. Los resultados indican que la absortividad y el tiempo necesario para deshidratar morteros de cal hidratada recién mezclados pueden ser controlados cuando el conglomerante es parcialmente remplazado por SCMs. La resistencia a compresión de los morteros CL90 aumenta sistem

  16. Thermo-Mechanical Compatibility of Viscoelastic Mortars for Stone Repair

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    Thibault Demoulin

    2016-01-01

    Full Text Available The magnitude of the thermal stresses that originate in an acrylic-based repair material used for the reprofiling of natural sandstone is analyzed. This kind of artificial stone was developed in the late 1970s for its peculiar property of reversibility in an organic solvent. However, it displays a high thermal expansion coefficient, which can be a matter of concern for the durability either of the repair or of the underlying original stone. To evaluate this risk we propose an analytical solution that considers the viscoelasticity of the repair layer. The temperature profile used in the numerical evaluation has been measured in a church where artificial stone has been used in a recent restoration campaign. The viscoelasticity of the artificial stone has been characterized by stress relaxation experiments. The numerical analysis shows that the relaxation time of the repair mortar, originating from a low T g , allows relief of most of the thermal stresses. It explains the good durability of this particular repair material, as observed by the practitioners, and provides a solid scientific basis for considering that the problem of thermal expansion mismatch is not an issue for this type of stone under any possible conditions of natural exposure.

  17. Carbonation and pH in mortars manufactured with supplementary cementitious materials

    Energy Technology Data Exchange (ETDEWEB)

    McPolin, D.O.; Basheer, P.A.M.; Long, A.E. [Queens University Belfast, Belfast (United Kingdom)

    2009-05-15

    An investigation of carbonation in mortars and methods of measuring the degree of carbonation and pH change is presented. The mortars were manufactured using ordinary portland cement, pulverized fuel ash, ground granulated blast-furnace slag, metakaolin, and microsilica. The mortars were exposed to a carbon dioxide-rich environment (5% CO{sub 2}) to accelerate carbonation. The resulting carbonation was measured using phenolphthalein indicator and thermogravimetric analysis. The pH of the pore fluid and a powdered sample, extracted from the mortar, was measured to give an accurate indication of the actual pH of the concrete. The pH of the extracted powder mortar sample was found to be similar to the pH of the pore fluid expressed from the mortars. The thermogravimetric analysis suggested two distinct regions of transport of CO{sub 2} within mortar, a surface region where convection was prevalent and a deeper region where diffusion was dominant. The use of microsilica has been shown to decrease the rate of carbonation, while pulverized fuel ash and ground granulated blast-furnace slag have a detrimental effect on carbonation. Metakaolin has little effect on carbonation.

  18. Mechanical properties of masonry repair dolomitic lime-based mortars

    OpenAIRE

    Lanas, J.; Perez, J. L.; Bello, M.A. (Miguel Ángel); Alvarez, J.I. (José Ignacio)

    2006-01-01

    180 different mortars made with a dolomitic lime and different aggregates were prepared in order to be used in restoration works. This paper focuses on the effect of technological variables on pore structure and mechanical properties of magnesian lime-based mortars. Compressive and flexural strengths of the specimens were discussed according to curing time, binder : aggregate ratios, attributes of the aggregates and porosity, at long-term tests. A strong increase in the strength of mortar...

  19. Characterization of diffusive transport in cementitious materials: influence of microstructure in mortars

    International Nuclear Information System (INIS)

    Concrete durability is a subject of considerable interest, especially with the use of cement based materials on structures increasingly demanding on term of sustainability and resistance to aggressive ions penetration or radionuclide release. Diffusion is considered as one of the main transport phenomena that cause migration of aggressive solutes and radionuclide in a porous media according to most studies. In order to enable more effective prediction of structures service life, the understanding of the link between cement based materials microstructure and transport macro properties needed to be enhanced. In this context, the present study is undertaken to enhance our understanding of the links between microstructure and tritiated water diffusivity in saturated mortars. The effect of aggregates via the ITZ (Interfacial Transition Zone) on transport properties and materials durability is studied. (author)

  20. Performance of Engineered Cementitious Composites for Concrete Repairs

    OpenAIRE

    Zhou, J.

    2011-01-01

    Background and goals of this thesis The concrete repair, rehabilitation and retrofitting industry grows rapidly, driven by deterioration of, damage to and defects in concrete structures. However, it is well known that to achieve durable concrete repairs is very difficult. The failure of concrete repairs causes high economical, social and environmental impacts. The main reason of failures is that most repair materials and the repair-substrate interface cannot withstand the high stresses induce...

  1. Mechanical interaction between historical brick and repair mortar: experimental and numerical tests

    International Nuclear Information System (INIS)

    An innovative laboratory procedure, developed at the Non Destructive Testing Laboratory of the Politecnico di Torino, as a preliminary design stage for the pre-qualification of repair mortars applied to historical masonry buildings is described. Tested repair mortars are suitable for new dehumidified plaster in order to stop the rising damp effects by capillary action on historical masonry walls. Long-term plaster delamination occurs frequently as a consequence of not compatible mechanical characteristics of mortar. Preventing this phenomenon is the main way to increase the durability of repair work. In this direction, it is useful to analyse, through the cohesive crack model, the evolutionary phenomenon of plaster delamination. The parameters used in the numerical simulation of experimental tests are able to characterize the mechanical behaviour of the interface. It is therefore possible to predict delamination in problems with different boundary conditions.

  2. RILEM TC 203-RHM: Repair mortars for historic masonry The role of mortar in masonry: an introduction to requirements for the design of repair mortars

    Czech Academy of Sciences Publication Activity Database

    Groot, C.; van Balen, K.; Bicer-Simsir, B.; Binda, L.; Elsen, J.; van Hees, R.; von Konow, T.; Lindqvist, J.; Mauerbrecher, P.; Papayanni, I.; Subercaseaux, M.; Tedeschi, C.; Toumbakari, E.; Thompson, M.; Válek, Jan; Veiga, R.

    2012-01-01

    Roč. 45, č. 9 (2012), s. 1287-1294. ISSN 1359-5997 Institutional support: RVO:68378297 Keywords : mortar * classification * requirements Subject RIV: JN - Civil Engineering Impact factor: 1.184, year: 2012

  3. Setup of Extruded Cementitious Hollow Tubes as Containing/Releasing Devices in Self-Healing Systems

    OpenAIRE

    Alessandra Formia; Salvatore Terranova; Paola Antonaci; Nicola Maria Pugno; Jean Marc Tulliani

    2015-01-01

    The aim of this research is to produce self-healing cementitious composites based on the use of cylindrical capsules containing a repairing agent. Cementitious hollow tubes (CHT) having two different internal diameters (of 2 mm and 7.5 mm) were produced by extrusion and used as containers and releasing devices for cement paste/mortar healing agents. Based on the results of preliminary mechanical tests, sodium silicate was selected as the healing agent. The morphological features of several mi...

  4. Strength and Density of Geopolymer Mortar Cured at Ambient Temperature for Use as Repair Material

    Science.gov (United States)

    Warid Wazien, A. Z.; Bakri Abdullah, Mohd Mustafa Al; Abd. Razak, Rafiza; Mohd Remy Rozainy, M. A. Z.; Faheem Mohd Tahir, Muhammad

    2016-06-01

    Geopolymers produced by synthesizing aluminosilicate source materials with an alkaline activator solution promised an excellent properties akin to the existing construction material. This study focused on the effect of various binder to sand ratio on geopolymer mortar properties. Mix design of geopolymer mortar was produced using NaOH concentration of 12 molars, ratio of fly ash/alkaline activator and ratio Na2SiO3/NaOH of 2.0 and 2.5 respectively. Samples subsequently ware cured at ambient temperature. The properties of geopolymer mortar were analysed in term of compressive strength and density at different period which are on the 3rd and 7th day of curing. Experimental results revealed that the addition of sand slightly increase the compressive strength of geopolymer. The optimum compressive strength obtained was up to 31.39 MPa on the 7th day. The density of geopolymer mortar was in the range between 2.0 g/cm3 to 2.23 g/cm3. Based on this findings, the special properties promoted by geopolymer mortar display high potential to be implemented in the field of concrete patch repair.

  5. FUNDAMENTAL PROPERTIES OF ULTRA HIGH PERFORMANCE-STRAIN HARDENING CEMENTITIOUS COMPOSITES AND USAGE FOR REPAIR

    Science.gov (United States)

    Kunieda, Minoru; Shimizu, Kosuke; Eguchi, Teruyuki; Ueda, Naoshi; Nakamura, Hikaru

    This paper presents the fundamental properties of Ultra High Performance-Strain Hardening Cementitious Composites (UHP-SHCC), which were depeloped for repair applications. In particular, mechanical properties such as tensile response, shrinkage and bond strength were investigated experimentally. Protective performance of the material such as air permeability, water permeability and penetration of chloride ion was also confirmed comparing to that of ordinary concrete. This paper also introduces the usage of the material in repair of concrete st ructures. Laboratory tests concerining the deterioration induced by corrosion were conducted. The UHP-SHCC that coverd the RC beam resisted not only crack opening along the rebar due to corrosion but also crack opening due to loading tests.

  6. Effects Of Grp Wastes On The Properties Of Self-Compacting Repair Mortars

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    Çağlar Yalçınkaya

    2013-03-01

    Full Text Available Self-compacting repair mortars (SCRM can flow through the narrow sections without vibration requirement. This study is aimed to search the utilization potential of glass reinforced plastic (GRP waste powders occurred during repairing ship and vessel. Six mixtures have been prepared with 1%, 2% and 3% GRP waste addition by volume into two different matrices including only cement binder as well as ground granulated blast furnace slag (GGBFS replaced 50% wt. of the cement binder. Workability of SCRM decreased as a result of GRP waste utilization. GRP wastes have exhibited different mechanical performance and early age autogenous shrinkage depending on the binder. The increment in GRP dosage caused an increase in early age autogenous shrinkage for matrix involving only cement binder while it caused a decrease in autogenous shrinkage value of GGBFS replaced matrix.

  7. Effect of the pre-treatment and the aggregate content on the adhesion strength of repair mortars on Miocene porous limestone

    Science.gov (United States)

    Szemerey-Kiss, Balázs; Török, Ákos

    2016-04-01

    The adhesion between porous limestone and newly prepared repair mortars are crucial in the preservation of historic stone structures. Besides mechanical compatibility other matches such as chemical composition and porosity are also essential, but the current research focuses on the adhesion strength of repair mortars that are used in the restoration of Hungarian porous limestone. 8 mortars (4 commercial and 4 specially prepared) were selected for the tests. Mortars with different amount of aggregate were prepared and caste to stone surface. The stone substrate was highly porous Miocene limestone. The strength was tested by standardized pull-out tests which method is commonly used for concrete testing. The limestone surfaces were either used in their natural conditions or were pre-treated (pre-wetting). The strength of the stone/mortar bond was tested. The failure mechanism was documented and various failure modes were identified. Strength test results suggest that especially pre-treatment influences strongly the pull-out strength at mortar/stone interface. Increasing aggregate content also reduces pull out strength of tested repair mortars, but at various rates depending on the mortar type. The financial support of OTKA post-doctoral grant to BSZK (reference number is: PD 112-955) and National Research, Development and Innovation (NKFI) Fund to ÁT (ref. no. K 116532) are appreciated.

  8. High-performance repair mortars for application in severe weathering environments: frost resistance assessment

    Czech Academy of Sciences Publication Activity Database

    Janotová, Dana; Nunes, Cristiana Lara; Slížková, Zuzana; Frankeová, Dita; Niedoba, Krzysztof

    Glasgow: University of the West of Scotland, 2013 - (Hughes, J.) ISBN 978-1-903978-44-3 R&D Projects: GA MK(CZ) DF11P01OVV008 Keywords : mortar * frost * durability * hydrophobic Subject RIV: AL - Art, Architecture, Cultural Heritage

  9. Masonry repair lime-based mortars: factors affecting the mechanical behavior

    International Nuclear Information System (INIS)

    The increasing use of lime-based mortars for the restoration of historic buildings and structures justifies the research on these materials. The focus of this paper is the effect of technological variables on pore structure and mechanical properties of lime-based mortars. The influence of curing time, binder-aggregate (B/Ag) ratio, aggregate attributes and porosity is discussed. Mortars prepared with aerial lime, varying aggregate types and B/Ag ratios ranging from 1:1 to 1:5 by volume were tested. Compressive and flexural strength measurements, as well as X-ray diffraction (XRD) and thermal studies, were performed after 3, 7, 28, 91, 182 and 365 days. A strong increase in strength of mortar mixtures after 365 curing days (as compared to 28 curing days) is found. In spite of the fact that larger amounts of binder increase the total porosity, the strength of these mixtures is also increased. A good interlocked structure is obtained as binder contents increase. Also, higher porosities allow better portlandite carbonation. A relationship between mechanical properties and pore structure was established. However, in case of binder excess, the increase in voids leads to a strength reduction. The use of calcareous aggregates improves strength more as compared to the use of siliceous aggregates. Factors as grain size distribution and grain shape of the aggregates have also been considered

  10. Lime-based repair mortars with water-repellent admixtures: laboratory durability assessment

    OpenAIRE

    Nunes, C.; Slížková, Z. (Zuzana)

    2015-01-01

    Conservation of architectural structures using lime binders is currently an important research topic aiming compatibility, durability and sustainability. In this study, lime (L) and lime-metakaolin (LM) mortars were prepared with the addition of water-repellent admixtures: linseed oil, stand oil and a silane based water-repellent. Experimental results demonstrate that oil imparts higher hydrophobicity to both L and LM mixtures. Durability was assessed through freeze-thaw and NaCl crystal...

  11. Properties of Fiber-Reinforced Mortars Incorporating Nano-Silica

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    Ahmed Ghazy

    2016-02-01

    Full Text Available Repair and rehabilitation of deteriorating concrete elements are of significant concern in many infrastructural facilities and remain a challenging task. Concerted research efforts are needed to develop repair materials that are sustainable, durable, and cost-effective. Research data show that fiber-reinforced mortars/concretes have superior performance in terms of volume stability and toughness. In addition, it has been recently reported that nano-silica particles can generally improve the mechanical and durability properties of cement-based systems. Thus, there has been a growing interest in the use of nano-modified fiber-reinforced cementitious composites/mortars (NFRM in repair and rehabilitation applications of concrete structures. The current study investigates various mechanical and durability properties of nano-modified mortar containing different types of fibers (steel, basalt, and hybrid (basalt and polypropylene, in terms of compressive and flexural strengths, toughness, drying shrinkage, penetrability, and resistance to salt-frost scaling. The results highlight the overall effectiveness of the NFRM owing to the synergistic effects of nano-silica and fibers.

  12. Behavior of Concrete Columns Repaired with Polymer Mortar and Epoxy Fiber Panel

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    Sungnam Hong

    2013-01-01

    Full Text Available Underwater structures are not easy to check for the degree of damage or to repair and strengthen damaged regions. Even during repair and strengthening, quality control is very difficult, because the work is done under water. Moreover, underwater structures severely deteriorate, owing to special environmental conditions. If this deterioration continues, the structures face serious structural problems, because of the corrosion of steel rods and the loss of concrete sections. Repairing or strengthening underwater structures requires effective, economic underwater repair and reinforcement techniques that allow the same working conditions as on the ground while maintaining dry condition for the repair sections. However, systematic studies on the repair and strengthening techniques for underwater structures are insufficient. This study proposes a new repair method for underwater structures, which applies epoxy fiber panel forms and shear connectors. To demonstrate the repair effects, this study compared and evaluated the failure modes and repair effects by the surface condition of repair sections, by applying various repair methods, in consideration of the ground and underwater conditions.

  13. Compatibility performance as a fundamental requirement for the repair of concrete structures with Self-Compacting Repair Mortars

    OpenAIRE

    Courard, Luc; Bissonnette, Benoît

    2007-01-01

    Durable adhesion of repair material on concrete substrate requires compatibility between the materials to be bonded. There are four main compatibility components to be addressed in any concrete repair scenario: dimensional, permeability, chemical and electrochemical compatibility. Among those, dimensional compatibility is often prevalent: while a cement-base repair material inevitably undergoes shrinkage, the substrate opposes to its free movement, a situation that can lead to cracking and, ...

  14. Behavior of Concrete Columns Repaired with Polymer Mortar and Epoxy Fiber Panel

    OpenAIRE

    Sungnam Hong; Sun-Kyu Park

    2013-01-01

    Underwater structures are not easy to check for the degree of damage or to repair and strengthen damaged regions. Even during repair and strengthening, quality control is very difficult, because the work is done under water. Moreover, underwater structures severely deteriorate, owing to special environmental conditions. If this deterioration continues, the structures face serious structural problems, because of the corrosion of steel rods and the loss of concrete sections. Repairing or streng...

  15. The effect of limestone powder, fly ash and silica fume on the properties of self-compacting repair mortars

    Indian Academy of Sciences (India)

    Selçuk Türkel; Yiğit Altuntaş

    2009-04-01

    Self-compacting repair mortars (SCRM) are preferred for the rehabilitation and repair of reinforced concrete structures especially at narrow mould systems. Self compactability and stability are susceptible to ternary effects of chemical and mineral admixture type and their content. In this study, the effect of limestone powder (LP) on the properties of SCRM has been compared with other mineral additives (silica fume (SF) and fly ash (FA) and their combinations) effects. Fresh properties, flexural and compressive strengths and water absorption properties of mortars were determined. The use of SF in mortars significantly increased the dosage of superplasticiser (SP). At the same constant SP dosage (0·8%) and mineral additives content (30%), LP can better improve the workability than that of control and FA mixtures by 19% and 27%. However, the results of this study suggest that certain FA, SF and LP combinations can improve the workability of SCRMs, more than FA, SF and LP alone. LP can have a positive influence on the mechanical performance at early strength development while SF improved aggregate-matrix bond resulting from the formation of a less porous transition zone in mortar. SF can better reducing effect on total water absorption while FA and LP will not have the same effect, at 28 days.

  16. Repair mortars for historic masonry Performance requirements for renders and plasters

    Czech Academy of Sciences Publication Activity Database

    Groot, C.; van Balen, K.; Bicer-Simsir, B.; Binda, L.; Elsen, J.; van Hees, R.; von Konow, T.; Lindqvist, JE.; Mauerbrecher, P.; Papayanni, I.; Subercaseaux, M.; Tedeschi, C.; Toumbakari, E.; Thompson, M.; Válek, Jan; Veiga, R.

    2012-01-01

    Roč. 45, č. 9 (2012), s. 1277-1285. ISSN 1359-5997 Institutional support: RVO:68378297 Keywords : renders * requirements * repair Subject RIV: JN - Civil Engineering Impact factor: 1.184, year: 2012

  17. 2nd Historic Mortars Conference

    CERN Document Server

    Hughes, John; Groot, Caspar; Historic Mortars : Characterisation, Assessment and Repair

    2012-01-01

    This volume focuses on research and practical issues connected with mortars on historic structures. The book is divided into four sections: Characterisation of Historic Mortars, Repair Mortars and Design Issues, Experimental Research into Properties of Repair Mortars, and Assessment and Testing. The papers present the latest work of researchers in their field. The individual contributions were selected from the contributions to the 2nd Historic Mortars Conference, which took place in Prague, September, 22-24, 2010. All papers were reviewed and improved as necessary before publication. This peer review process by the editors resulted in the 34 individual contributions included in here. One extra paper reviewing and summarising State-of-the-Art knowledge covered by this publication was added as a starting and navigational point for the reader. The editors believe that having these papers in print is important and they hope that it will stimulate further research into historic mortars and related subjects. 

  18. Tensile Bond Between Substrate Concrete and Normal Repairing Mortar under Freeze–Thaw Cycles

    OpenAIRE

    Qian, Ye; Zhang, Dawei; Ueda, Tamon

    2014-01-01

    Concrete patch repair has long been used to repair the damaged concrete structures. In cold regions, freeze– thaw cycle is one of the major damage factors. Not only the material itself is damaged by freeze–thaw cycles, but also the adhesive interface, which is regarded as the weakest part of composite system, degrades under freeze–thaw cycles. Air entraining agent has long been used to increase the freeze–thaw resistance of concrete materials. However, the effect of air entraining agent on th...

  19. Repairing cracks developed in mortar beams reinforced by cold-drawn NiTi or NiTiNb SMA fibers

    Science.gov (United States)

    Choi, Eunsoo; Kim, Dong Joo; Youn, Heejung; Nam, Tae-hyun

    2015-12-01

    In this study, mortar beams reinforced by shape memory alloy (SMA) fibers of NiTi and NiTiNb alloys were prepared to perform crack-repairing tests using three-point bending tests. The SMA fibers had a length of 30 mm, and their types were straight, dog-bone, and dog-bone with paper wrapping. For the bending tests, twelve types of mortar beams with the dimensions of 40 mm × 40 mm × 160 mm (B × H × L) were prepared. Half of them had a top steel reinforcement, and equal numbers of beams were assigned to the NiTi and NiTiNb fibers. Five SMA fibers were located at the bottom center of the beams along with an artificial crack of 10 mm depth and 1 mm thickness. Epoxy was used to fill the cracks to bond the cracked surfaces using injection, and a hot-gun was used to heat the SMA fibers in the cracks. The crack widths were measured before and after the cracks were repaired, and force-displacement curves were obtained to assess the flexural strength recovery ratio of the beams. It does not appear that the crack-closing capacity of SMA fibers is a crucial factor to recover the flexural strength in repaired beams. However, adequate application of epoxy is critical for repairing cracks, and the residual stress of SMA fibers seems to contribute to increase flexural strength of repaired beams. The residual stress of SMA fibers functions as prestress on mortar and delays the initiation of cracking.

  20. Chloride diffusion in partially saturated cementitious material

    DEFF Research Database (Denmark)

    Nielsen, Erik Pram; Geiker, Mette Rica

    2003-01-01

    The paper proposes a combined application of composite theory and Powers' model for microstructural development for the estimation of the diffusion coefficient as a function of the moisture content of a defect-free cementitious material. Measurements of chloride diffusion in mortar samples (440 kg...

  1. 水下快速修补砂浆的性能研究%Study on the properties of underwater rapid repair mortar

    Institute of Scientific and Technical Information of China (English)

    潘微旺

    2013-01-01

    基于水工混凝土中的缺陷位置富含水分的特点,研究了在水下具有良好抗分散性、流动性和快速修补特点的水下快速修补砂浆,并研究了灰砂比、水灰比和水下抗分散剂掺量对水下快速修补砂浆的流动性、凝结时间、水下抗分散性和强度的影响.结果表明,水下快速修补砂浆1、3、7和28 d的水陆强度比达到80%以上,且在水下具有良好的自流平、自密实性能.%Based on the feature that the defect locations of hydraulic concrete is rich in water, this paper studied the underwater rapid repair mortar with good underwater anti-dispersion,mobility and rapid repair characteristics,and studied the influence of the cement-sand ratio,water-cement ratio and the dosage of underwater anti-dispersants on the fluidity, setting time, underwater anti-dispersion and strength properties of underwater rapid repair mortar. The results show that the 1,3,7 and 28 d land and water intensity ratio of underwater rapid repair mortar reached more than 80%, and having good underwater self-leveling and self-compacting properties.

  2. Carbonatation Influence on Fly Ash and Portland Cement Mortars

    OpenAIRE

    P.L. Valdez–Tamez; A. Durán–Herrera; G. Fajardo–San Miguel; C.A. Juárez–Alvarado

    2009-01-01

    The influence of carbonation on mortars containing 25% of fly ash instead of the cementitious materials was studied. Mortar cylinder specimens were fabricated for 4 different W/C ratios: 0.35, 0.45, 0.55 and 0.65. Mortars with and without fly ash were subjected to an accelerated carbonation process. Volumetric weight, water absorption, compressive strength, water permeability, pH and mercury intrusion porosimetry of the mortar specimens were determined. Due to the fly ash pozzolanic potential...

  3. Setup of Extruded Cementitious Hollow Tubes as Containing/Releasing Devices in Self-Healing Systems

    Directory of Open Access Journals (Sweden)

    Alessandra Formia

    2015-04-01

    Full Text Available The aim of this research is to produce self-healing cementitious composites based on the use of cylindrical capsules containing a repairing agent. Cementitious hollow tubes (CHT having two different internal diameters (of 2 mm and 7.5 mm were produced by extrusion and used as containers and releasing devices for cement paste/mortar healing agents. Based on the results of preliminary mechanical tests, sodium silicate was selected as the healing agent. The morphological features of several mix designs used to manufacture the extruded hollow tubes, as well as the coatings applied to increase the durability of both core and shell materials are discussed. Three-point bending tests were performed on samples produced with the addition of the above-mentioned cementitious hollow tubes to verify the self-healing effectiveness of the proposed solution. Promising results were achieved, in particular when tubes with a bigger diameter were used. In this case, a substantial strength and stiffness recovery was observed, even in specimens presenting large cracks (>1 mm. The method is inexpensive and simple to scale up; however, further research is needed in view of a final optimization.

  4. An Integrated Experimental-Numerical Study of the Performance of Lime-Based Mortars in Masonry Piers Under Eccentric Loading

    OpenAIRE

    Nežerka, Václav; Antoš, Jakub; Litoš, Jiří; Tesárek, Pavel; Zeman, Jan

    2015-01-01

    Architectural conservation and repair are becoming increasingly important issues in many countries due to numerous prior improper interventions, including the use of inappropriate repair materials over time. As a result, the composition of repair masonry mortars is now being more frequently addressed in mortar research. Just recently, for example, it has become apparent that Portland cement mortars, extensively exploited as repair mortars over the past few decades, are not suitable for repair...

  5. Bending performance of concrete beams strengthened with textile reinforced mortar TRM

    OpenAIRE

    Gil Espert, Lluís; Escrig Pérez, Christian; Bernat Masó, Ernest

    2013-01-01

    This work presents a method of strengthening concrete structures based on textiles of high strength and mortars. The combination of textiles and mortars produces a new composite material with cementitious matrix. This material can be used for the reinforcement of concrete beams under bending loads. We tested several combinations of fibers: glass, Poliparafenil Benzobisoxazol (PBO), steel and carbon fibers with mortar and we used them to reinforce precast concrete beams. All the specimens were...

  6. Microfibres and hydrogels to promote autogenous healing in cementitious materials

    OpenAIRE

    Snoeck, Didier; Dubruel, Peter; De Belie, Nele

    2013-01-01

    Cementitious materials are sensitive to crack formation and it would be beneficial if the material could stop the crack propagation, repair the damage and reach again the original liquid-tightness and/or strength. Therefore, a cementitious material with synthetic microfibres and superabsorbent polymers (SAPs) is proposed. Upon crack formation, the microfibres will become active and due to the bridging action, they will stop the opening of a crack, forcing the cementitious material to crack so...

  7. Carbonatation Influence on Fly Ash and Portland Cement Mortars

    Directory of Open Access Journals (Sweden)

    P.L. Valdez–Tamez

    2009-01-01

    Full Text Available The influence of carbonation on mortars containing 25% of fly ash instead of the cementitious materials was studied. Mortar cylinder specimens were fabricated for 4 different W/C ratios: 0.35, 0.45, 0.55 and 0.65. Mortars with and without fly ash were subjected to an accelerated carbonation process. Volumetric weight, water absorption, compressive strength, water permeability, pH and mercury intrusion porosimetry of the mortar specimens were determined. Due to the fly ash pozzolanic potential, for all W/C ratios, results of the compressive strength tests at 28 days of the mortars with and without fly ash were similar. Mortars with fly ash presented similar water permeability as mortars without fly ash. PH results showed that alkalinity reduction is lower in mortars with fly ash compared to those containing cement only. In all the mortars, the porosimetric analysis indicated that porosity is reduced due to carbonation. Further more, it is showed the predominance of the macro and mesopores.

  8. Rendering mortars in Medina Azahara, Part I: Material characterization and alteration process

    OpenAIRE

    Blanco-Varela, M. T.; Puertas, F.; Palomo, A.

    1997-01-01

    Rendering mortars, which are still exposed to the open air on some of the walls of Medina Azahara, are studied and characterized in this work. Some repairing mortars used in different previous restorations are also characterized. Those rendering mortars are of different make considering the composition of their binder: lime, gypsum and mixed lime/ gypsum. Repairing mortars used in previous interventions are made of lime, excepting for a portland cement used by Félix Hernández in the rest...

  9. Cementitious artificial aggregate particles for high-skid resistance pavements

    OpenAIRE

    De Larrard, François; MARTINEZ CASTILLO, Rafael; Sedran, Thierry; HAUZA, Philippe; Poirier, Jean Eric

    2012-01-01

    For some critical road sections, a high skid resistance of wearing course is required to minimise the risk of traffic accidents. Nowadays this skid resistance is mainly brought by the use of special aggregates as calcined bauxite, a scarce and expensive material. The paper presents a patented technology, where a special high-performance mortar is produced and crushed at early age. These cementitious artificial aggregates (CAA) can display aggregate properties close to those of calcined bauxit...

  10. Lime-based mortars with linseed oil: sodium chloride resistance assessment and characterization of the degraded material

    OpenAIRE

    Nunes, C.; Slížková, Z. (Zuzana); Janotová, D. (Dana)

    2013-01-01

    Lime mortar is often used to repair historic buildings but is prone to salt crystallization with deleterious consequences. Lime mortar is a very susceptible material due to its high porosity and low mechanical resistance. Recent findings concerning mortar additives that impart hydrophobic properties to mortar show that by limiting water penetration, damage from frost and salt can be decreased. Linseed oil was commonly used in former times as an additive for mortar in order to grant hydrophobi...

  11. Performance of Polymer Modified Mortar with Different Dosage of Polymeric Modifier

    OpenAIRE

    Ganesan Shankar; Othuman Mydin Md Azree; Sani Norazmawati Md.; Che Ani Adi Irfan

    2014-01-01

    Polymer modified mortar system is defined as hydraulic cement combined at the time of mixing with organic polymers that are dispersed or re-dispersed in water, with or without aggregates. The compressive strength and flexural strength of polymer modified mortar obtained at early age are low and it required prolong curing period for the strength enhancement. In order to enhance the mechanical properties of cementitious mixture as well as its durability, hybridization of polymeric modifiers are...

  12. Properties of wastepaper sludge in geopolymer mortars for masonry applications.

    Science.gov (United States)

    Yan, Shiqin; Sagoe-Crentsil, Kwesi

    2012-12-15

    This paper presents the results of an investigation into the use of wastepaper sludge in geopolymer mortar systems for manufacturing construction products. The investigation was driven by the increasing demand for reuse options in paper-recycling industry. Both fresh and hardened geopolymer mortar properties are evaluated for samples incorporating dry wastepaper sludge, and the results indicate potential end-use benefits in building product manufacture. Addition of wastepaper sludge to geopolymer mortar reduces flow properties, primarily due to dry sludge absorbing water from the binder mix. The average 91-day compressive strength of mortar samples incorporating 2.5 wt% and 10 wt% wastepaper sludge respectively retained 92% and 52% of the reference mortar strength. However, contrary to the normal trend of increasing drying shrinkage with increasing paper sludge addition to Portland cement matrices, the corresponding geopolymer drying shrinkage decreased by 34% and 64%. Equally important, the water absorption of hardened geopolymer mortar decreased with increasing paper sludge content at ambient temperatures, providing good prospects of overall potential for wastepaper sludge incorporation in the production of building and masonry elements. The results indicate that, despite its high moisture absorbance due to the organic matter and residual cellulose fibre content, wastepaper sludge appears compatible with geopolymer chemistry, and hence serves as a potential supplementary additive to geopolymer cementitious masonry products. PMID:22868380

  13. Standard Test Method for Autogenous Strain of Cement Paste and Mortar

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Lura, Pietro; Goodwin, Fred;

    This test method measures the bulk strain of a sealed cement paste or mortar specimen, including those containing admixtures, various supplementary cementitious materials (SCM), and other fine materials, at constant temperature and not subjected to external forces, from the time of final setting...

  14. Micro-mechanical Analysis of Fiber Reinforced Cementitious Composites using Cohesive Crack Modeling

    DEFF Research Database (Denmark)

    Dick-Nielsen, Lars; Stang, Henrik; Poulsen, Peter Noe

    2006-01-01

    This paper discusses the mechanism appearing during fiber debonding in fiber reinforced cementitious composite. The investigation is performed on the micro scale by use of a Finite Element Model. The model is 3 dimensional and the fictitious crack model and a mixed mode stress formulation are...... implemented. It is shown that the cohesive law for a unidirectional fiber reinforced cementitious composite can be found through superposition of the cohesive law for mortar and the fiber bridging curve. A comparison between the numerical and an analytical model for fiber pull-out is performed....

  15. A review: Self-healing in cementitious materials and engineered cementitious composite as a self-healing material

    DEFF Research Database (Denmark)

    Wu, Min; Johannesson, Björn; Geiker, Mette

    2012-01-01

    Cementitious materials are the most widely used building materials all over the word. However, deterioration is inevitable even since the very beginning of the service life, then maintenance and repair work, which are often labor- and capital-intensive, would be followed. Thus, self-healing of th...

  16. Influence of curing conditions on lime and lime-metakaolin mortars

    OpenAIRE

    Faria, Paulina; Martins, A

    2011-01-01

    Comunicação apresentada ao XII DBMC - International Conference on Durability of Building Materials and Components, Porto, April 12th-15th, 2011 Air-lime mortars with or without pozzolanic components were largely used in historic buildings. Due to natural or accidental degradation it is often necessary the application of repair mortars, durable and compatible with the masonries of historic buildings. Within this context and associating the improvement of mortars characteristics to the ne...

  17. Innovative mix design of cementitious materials for enhancing strength and ductility

    OpenAIRE

    Ahmad, Sajjad

    2015-01-01

    Cement based composites i.e. paste, mortar and concrete are the most utilized materials in the construction industry all over the world. Cement composites are quasi-brittle in nature and possess extremely low tensile strength as compared to their compressive strength. Due to their low tensile strength capacity, cracks develop in cementitious composites due to the drying shrinkage, plastic settlements and/or stress concentrations (due to external restrains and/or applied stresses) etc. These c...

  18. Study on the alteration of hydrogeological and mechanical properties of the cementitious Material. 3

    International Nuclear Information System (INIS)

    We experimentally investigated the influence of several phenomena at the disposal environment, to evaluate the long-term alteration of cementitious material. The results are shown below. 1. Hardened cement paste specimens were altered and characterized after artificial seawater permeation. The calcium dissolution was accelerated, and secondary minerals containing magnesium were deposited. The permeability became one to three orders of magnitude smaller than data from specimens altered by deionized water permeation. It was estimated that secondary mineral formations reduced the permeability. These results meant that seawater and pure water differ remarkably from each other in influence to alteration of cementitious material. 2. Two type mixture proportions concrete, two type mixture proportions mortar and a cement paste under same W/C ratio 55% were characterized, to apply the accumulated data of paste to concrete or mortar. Compressive strength of paste was lower than that of concrete and mortar. It was contrary to the previous report. The behavior of Young's modulus and Poisson's ratio could be explained well using amount of aggregate. The data of permeability meant that boundary between aggregate and cement paste didn't become path of water flow, and that aggregate disturbed permeation. 3. Self-sealing property of cracked specimen of cementitious material were investigated by the water permeation test using sodium bicarbonate solution. The permeability decreased in two orders of magnitude, and possibility of sealing was suggested. By the morphology, the deposits in the cracks might be portlandite and C-S-H, and be not calcium carbonate. 4. Alteration of characteristics of cementitious material in sodium-nitrate and ammonia solution was evaluated by the water permeation test. Alteration degree of the nitrate and ammonia solution case showed similar trend to that of the sodium nitrate solution case. This result meant that ammonia solution would not influence the

  19. Leaching characteristics of steel slag components and their application in cementitious property prediction.

    Science.gov (United States)

    Li, Zaibo; Zhao, Sanyin; Zhao, Xuguang; He, Tusheng

    2012-01-15

    High-efficiency recovery and utilization of steel slag are important concerns for environmental protection and sustainable development. To establish a rapid method to evaluate the cementitious properties of steel slag, leaching tests were carried out on steel slag components via an evaporation-condensation method; the leaching characteristics and mechanism of the slag were also investigated. The relationship between leaching characteristics and cementitious properties, which were represented by mortar compressive strength, was analyzed. Results show that there exist significant differences among the amounts of chemically active leached components. The leaching process can be described by the shrinking unreacted core model controlled by intra-particle diffusion, and is in accordance with Kondo R hydration kinetics equation. The leaching process showed a good linear relationship between the amounts of components leached from steel slag and the mortar compressive strength of cementitious materials prepared from reference cement and steel slag with mass ratios of 50:50 and 70:30. The compressive strengths of mortars subjected to 7, 28, and 90 days of curing can be accurately predicted by the sum of leached (CaO+Al(2)O(3)) obtained after a certain length of leaching time. PMID:22088502

  20. Reuse of de-inking sludge from wastepaper recycling in cement mortar products.

    Science.gov (United States)

    Yan, Shiqin; Sagoe-Crentsil, Kwesi; Shapiro, Gretta

    2011-08-01

    This paper presents results of an investigation into the use of de-inking sludge from a paper recycling mill as feedstock material in the manufacture of cement mortar products, including masonry blocks and mortar renders. Both physical and mechanical properties of mortar specimens containing various amounts of de-inking sludge were investigated. It was observed that the addition of de-inking sludge to cement mortar at a fixed water-to-cement ratio significantly reduced flow properties and increased setting time. Water absorption and volume of permeable voids of cement mortar increased with increased dosage of de-inking sludge, with a corresponding reduction of bulk density. The 91-day compressive strength of mortar samples with 2.5 wt% and 20 wt% de-inking sludge loadings retained 83% and 62% respectively of the reference mortar strength. The corresponding drying shrinkage increased by up to 160% compared to reference samples. However, a de-inking sludge loading of up to 2.5 wt% did not significantly alter measured physical and mechanical properties. The results demonstrate that despite the high moisture absorbance of de-inking sludge due to its organic matter and residual cellulose fibre content, it serves as a potential supplementary additive and its cellulosic content proving to be an active set retardant to cementitious masonry products. PMID:21507557

  1. Iron ore tailings used for the preparation of cementitious material by compound thermal activation

    Institute of Scientific and Technical Information of China (English)

    Zhong-lai Yi; Heng-hu Sun; Xiu-quan Wei; Chao Li

    2009-01-01

    In the background of little reuse and large stockpile for iron ore railings, iron ore tailing from Chinese Tonghua were used as raw material to prepare cementitious materials. Cementitious properties of the iron ore tailings activated by compound thermal ac-tivation were studied. Testing methods, such as XRD, TG-DTA, and IR were used for researching the phase and structure variety of the iron ore tailings in the process of compound thermal activation. The results reveal that a new cementitious material that contains 30wt% of the iron ore tailings can be obtained by compounded thermal activation, whose mortar strength can come up to the stan-dard of 42.5 cement of China.

  2. Cementitious Composites Engineered with Embedded Carbon Nanotube Thin Films for Enhanced Sensing Performance

    Science.gov (United States)

    Loh, Kenneth J.; Gonzalez, Jesus

    2015-07-01

    Cementitious composites such as concrete pavements are susceptible to different damage modes, which are primarily caused by repeated loading and long-term deterioration. There is even greater concern that damage could worsen and occur more frequently with the use of heavier vehicles or new aircraft carrying greater payloads. Thus, the objective of this research is to engineer cementitious composites with capabilities of self-sensing or detecting damage. The approach was to enhance the damage sensitivity of cementitious composites by incorporating multi-walled carbon nanotubes (MWNT) as part of the mix design and during casting. However, as opposed to directly dispersing MWNTs in the cement matrix, which is the current state-of-art, MWNT-based thin films were airbrushed and coated onto sand particles. The film-coated sand was then used as part of the mix design for casting mortar specimens. Mortar specimens were subjected to compressive cyclic loading tests while their electrical properties were recorded simultaneously. The results showed that the electrical properties of these cementitious composites designed with film-coated sand exhibited extremely high strain sensitivities. The electrical response was also stable and consistent between specimens.

  3. Comparing the Environmental Impacts of Alkali Activated Mortar and Traditional Portland Cement Mortar using Life Cycle Assessment

    Science.gov (United States)

    Matheu, P. S.; Ellis, K.; Varela, B.

    2015-11-01

    Since the year 1908 there has been research into the use alkali activated materials (AAM) in order to develop cementitious materials with similar properties to Ordinary Portland Cement. AAMs are considered green materials since their production and synthesis is not energy intensive. Even though AAMs have a high compressive strength, the average cost of production among other issues limits its feasibility. Previous research by the authors yielded a low cost AAM that uses mine tailings, wollastonite and ground granulated blast furnace slag (GGBFS). This mortar has an average compressive strength of 50MPa after 28 days of curing. In this paper the software SimaPro was used to create a product base cradle to gate Life Cycle Assessment (LCA). This compared the environmental impact of the AAM mortar to an Ordinary Portland Cement mortar (PCHM) with similar compressive strength. The main motivation for this research is the environmental impact of producing Ordinary Portland Cement as compared to alkali activated slag materials. The results of this LCA show that the Alkali Activated Material has a lower environmental impact than traditional Portland cement hydraulic mortar, in 10 out of 12 categories including Global Warming Potential, Ecotoxicity, and Smog. Areas of improvement and possible future work were also discovered with this analysis.

  4. 3D morphological and micromechanical modeling of cementitious materials

    International Nuclear Information System (INIS)

    The goal of this thesis is to develop morphological models of cementitious materials and use these models to study their local and effective response. To this aim, 3D images of cementitious materials (mortar and concrete), obtained by micro-tomography, are studied. First, the mortar image is segmented in order to obtain an image of a real microstructure, to be used for linear elasticity computations. The image of concrete is used, after being processed, to determine various morphological characteristics of the material. A random model of concrete is then developed and validated by means of morphological data. This model is made up of three phases, corresponding to the matrix, aggregates and voids. The aggregates phase is modelled by implantation of Poisson polyhedra without overlap. For this purpose, an algorithm suited to the vector generation of Poisson polyhedra is introduced and validated with morphological measurements. Finally, the effective linear elastic properties of the mortar and other simulated microstructures are estimated with the FFT (Fast-Fourier Transform) method, for various contrasts between the aggregates and matrix' Young moduli. To complete this work, focused on effective properties, an analysis of the local elastic response in the matrix phase is undertaken, in order to determine the spatial arrangement between stress concentration zones in the matrix and the phases of the microstructure (aggregates and voids). Moreover, a statistical fields characterization, in the matrix, is achieved, including the determination of the Representative Volume Element (RVE) size. Furthermore, a comparison between effective and local elastic properties obtained from microstructures containing polyhedra and spheres is carried out. (author)

  5. Comparative experimental study of dynamic compressive strength of mortar with glass and basalt fibres

    OpenAIRE

    Kruszka Leopold; Moćko Wojciech; Fenu Luigi; Cadoni Ezio

    2015-01-01

    Specimen reinforced with glass and basalt fibers were prepared using Standard Portland cement (CEM I, 52.5 R as prescribed by EN 197-1) and standard sand, in accordance with EN 196-1. From this cementitious mixture, a reference cement mortar without fibers was first prepared. Compressive strength, modulus of elasticity, and mod of fracture were determined for all specimens. Static and dynamic properties were investigated using Instron testing machine and split Hopkinson pressure bar, respecti...

  6. Electrohydraulic shock wave generation as a means to increase intrinsic permeability of mortar

    OpenAIRE

    MAUREL, O.; REESS, T.; MATALLAH, M.; FERRON, A.; Chen, W.; C. La Borderie; G. Pijaudier-Cabot; JACQUESE, A.; REY-BETHBEDER, F.

    2010-01-01

    This article discusses the influence of compressive shock waves on the permeability of cementitious materials. Shock waves are generated in water by Pulsed Arc Electrohydraulic Discharges (PAED). The practical aim is to increase the intrinsic permeability of the specimens. The maximum pressure amplitude of the shock wave is 250 MPa. It generates damage in the specimens and the evolution of damage is correlated with the intrinsic permeability of the mortar. A threshold of pressure is observed....

  7. TECHNOLOGICAL PROPERTIES OF CONCRETES AND MORTARS FOR UNDERWATER CONCRETING

    OpenAIRE

    O. V. Anufrieva; B. H. Klochko

    2009-01-01

    The article is about the results of experimental-and-theoretical research of usefulness of mortar and concrete mixes for underwater repair works. It is shown that the developed compositions of hydraulic engineering concretes are characterized by high effectiveness in the corrosive medium.

  8. TECHNOLOGICAL PROPERTIES OF CONCRETES AND MORTARS FOR UNDERWATER CONCRETING

    Directory of Open Access Journals (Sweden)

    O. V. Anufrieva

    2009-03-01

    Full Text Available The article is about the results of experimental-and-theoretical research of usefulness of mortar and concrete mixes for underwater repair works. It is shown that the developed compositions of hydraulic engineering concretes are characterized by high effectiveness in the corrosive medium.

  9. Strength and shrinkage properties of mortar containing a nonstandard high-calcium fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Cengiz Duran Atis; Alaettin Kilic; Umur Korkut Sevim [Cukurova University, Balcali-Adana (Turkey). Engineering and Architecture Faculty

    2004-01-01

    A laboratory study was undertaken to assess the compressive and flexural tensile strength and drying shrinkage properties of mortar mixtures containing high-calcium nonstandard Afsin-Elbistan fly ash (FA). Possibility of using Afsin-Elbistan FA in cement-based materials as shrinkage-reducing or compensation agent was also discussed. Five mortar mixtures including control Portland cement (PC) and FA mortar mixtures were prepared. FA replaced the cement on mass basis at the replacement ratios of 10%, 20%, 30% and 40%. Water-cementitious materials ratio was 0.4 for all mixtures. The mixtures were cured at 65% relative humidity and 20{+-}2{sup o}C. The compressive and flexural tensile strength and drying shrinkage values of the mortar mixtures were measured. The results show that Afsin-Elbistan FA reduced drying shrinkage of the mortar by 40%. Therefore, it was concluded that Afsin-Elbistan FA can be used as a shrinkage-reducing agent. The mortar containing 40% FA expanded. This indicates that Afsin-Elbistan FA may be utilized to compensate drying shrinkage of cement-based materials.

  10. Performance of Polymer Modified Mortar with Different Dosage of Polymeric Modifier

    Directory of Open Access Journals (Sweden)

    Ganesan Shankar

    2014-01-01

    Full Text Available Polymer modified mortar system is defined as hydraulic cement combined at the time of mixing with organic polymers that are dispersed or re-dispersed in water, with or without aggregates. The compressive strength and flexural strength of polymer modified mortar obtained at early age are low and it required prolong curing period for the strength enhancement. In order to enhance the mechanical properties of cementitious mixture as well as its durability, hybridization of polymeric modifiers are applied into cementitious mixture specimens. Thus, this study is intended to examine the mechanical properties of hybrid polymer modified mortar system at various levels of polymeric modifier dosage; styrene-butadiene rubber (SBR latex and epoxy resin. Laboratory tests for density, compressive strength and flexural strength were carried out to determine the strength of hybrid polymer modified mortar. In this study, the hybrid polymer of SBR latex with epoxy resin gives discontented results compared to unmodified cement system. The results of density, compressive strength and flexural strength of hybrid polymer modified cement system had shown negative outcomes and did not make any improvement to cement system.

  11. Influence of bicarbonate ions on the deterioration of mortar bars in sulfate solutions

    International Nuclear Information System (INIS)

    This work investigates the influence of bicarbonate ions on the deterioration of cementitious material exposed to sulfate ions. Mortars based on a CEM I and on a CEM III/B cement were investigated. Experimental investigations were compared to thermodynamic modeling and phase characterization to understand the differences in deterioration. The presence of bicarbonate ions significantly reduced the expansion of the CEM I mortars. Thermodynamic modeling showed that at high concentrations of bicarbonate ettringite and gypsum become unstable. Microstructural characterization combined with information from thermodynamic modeling suggests that conditions of high supersaturation with respect to ettringite are unlikely in the samples exposed in solutions containing bicarbonate. Consequently, expansive forces are not generated by the crystallization pressure of ettringite. There was little expansion of the CEM III/B sample even in the sodium sulfate solution. In the bicarbonate solution this mortar showed a highly leached zone at the surface in which calcite was observed.

  12. Influence of bicarbonate ions on the deterioration of mortar bars in sulfate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kunther, W., E-mail: Wolfgang.Kunther@empa.ch [Empa, Laboratory for Concrete and Construction Chemistry, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Lothenbach, B. [Empa, Laboratory for Concrete and Construction Chemistry, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Scrivener, K. [EPFL, Laboratory of Construction Materials, CH-1015 Lausanne (Switzerland)

    2013-02-15

    This work investigates the influence of bicarbonate ions on the deterioration of cementitious material exposed to sulfate ions. Mortars based on a CEM I and on a CEM III/B cement were investigated. Experimental investigations were compared to thermodynamic modeling and phase characterization to understand the differences in deterioration. The presence of bicarbonate ions significantly reduced the expansion of the CEM I mortars. Thermodynamic modeling showed that at high concentrations of bicarbonate ettringite and gypsum become unstable. Microstructural characterization combined with information from thermodynamic modeling suggests that conditions of high supersaturation with respect to ettringite are unlikely in the samples exposed in solutions containing bicarbonate. Consequently, expansive forces are not generated by the crystallization pressure of ettringite. There was little expansion of the CEM III/B sample even in the sodium sulfate solution. In the bicarbonate solution this mortar showed a highly leached zone at the surface in which calcite was observed.

  13. Simple Mechanical Beneficiation Method of Coarse Fly Ash with High LOI for Making HVFA Mortar

    Directory of Open Access Journals (Sweden)

    Antoni ,

    2015-01-01

    Full Text Available This study focusses on the effect of milling of fly ash obtained from four different sources on the properties of high volume fly ash (HVFA mortar. Two fly ash samples with low loss-on-ignition (LOI were taken from a coal-fired power plant, while the other two with high LOIs were obtained from a textile factory and from a paper mill, respectively. Milling was performed using a rod mill at a certain period of time. The workability of HVFA mortar with constant water to cementitious ratio was controlled by adjusting the superplasticizer content. The results show that the specific gravity of fly ash increases after milling. Utilizing milled fly ash ends up with significant strength increase of HVFA mortar, especially those utilizing high LOI fly ash. This shows that milling is an excellent fly ash beneficiation technique, especially on the one with high LOI value.

  14. Properties of Fiber-Reinforced Mortars Incorporating Nano-Silica

    OpenAIRE

    Ahmed Ghazy; Mohamed T. Bassuoni; Eugene Maguire; Mark O’Loan

    2016-01-01

    Repair and rehabilitation of deteriorating concrete elements are of significant concern in many infrastructural facilities and remain a challenging task. Concerted research efforts are needed to develop repair materials that are sustainable, durable, and cost-effective. Research data show that fiber-reinforced mortars/concretes have superior performance in terms of volume stability and toughness. In addition, it has been recently reported that nano-silica particles can generally improve the m...

  15. Shrinkage and Cracking Sensitivity of Cement Mortar Containing Fly Ash, Granulated Blast-furnace Slag and Silica Fume

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A laboratory study was undertaken to investigate drying shrinkage and cracking sensitivity subjected to restrained shrinkage of mortar containing fly ash (FA), granulated blast-furnace slag (GBFS) and silica fume (SF). Six mortar mixtures including control Portland cement (PC) and FA,GBFS and SF mortar mixtures were prepared. FA replaced the cement on mass basis at the replacement ratios of 20% and 35%, GBFS replaced the cement at the replacement ratios of 40%, SF replaced the cement at the replacement ratios of 8% and the blended mixtures with 20% FA, 20% GBFS and 8% SF. Water-cementitious materials ratio and sand-cementitious materials ratio were 0.4 and 2.0 for all mixtures, respectively. The mixtures were cured at 65% relative humidity and 20℃. The drying shrinkage value, initial cracking time and cracking width of the mortar samples were measured. The results show that all the mortar mixture containing FA exhibited the decrease of drying shrinkage.Moreover, initial cracking time was markedly delayed, and the crack width of the initial crack was reduced. However, the incorporations of various ratios of GBFS and SF led to an increase of drying shrinkage, initial cracking time and cracking width as compared to control mixture.

  16. Restrained Shrinkage-Induced Cracking of Light Weight High Performance Fiber Reinforced Cementitious Composites

    Directory of Open Access Journals (Sweden)

    Shaikh F.U Ahmed

    2009-01-01

    Full Text Available Problem statement: Shrinkage induced cracking cause damage to reinforced concrete structures. An experimental study was conducted on restrained shrinkage test of cement mortar and light weight High Performance Fiber Reinforced Cementitious Composites (HPFRCC. Approach: Two types of light weight HPFRCC and a premix mortar containing small amount of fiber were included in the experiment. Results: Results showed the multiple cracks, as many as 49, in light weight HPFRCC specimens compared to few cracks (about six cracks in the premix mortar specimen. At the end of shrinkage test, the width of the cracks in the mortar specimen was more than 250 μm with the largest crack width of about 400 μm. However, the scenario was quite different in light weight HPFRCC specimens, where the width of almost all cracks was less than 100 μm. Conclusion: The higher number of multiple cracks with small cracks width in light weight HPFRCC specimens due to drying shrinkage was due to their strain hardening and ductile behavior compared to quasi brittle behavior of premix mortar where less number of wide cracks was observed.

  17. Rapid Repair of Earthquake Damaged RC Interior Beam-wide Column Joints and Beam-wall Joints Using FRP Composites

    Institute of Scientific and Technical Information of China (English)

    LI Bing; LIM Chee Leong

    2009-01-01

    This paper studies the seismic performance of FRP-strengthened RC interior non-seismically detailed beam-wide columns and beam-wall joints after limited seismic damage. Four eccentric and concentric beam-wide column joints and two beam-wall joints, initially damaged in a previous study, were repaired and tested under constant axial loads (0. \\fc'Ag and 0. 35 fc'Ag ) and lateral cyclic loading. The rapid repair technique developed, aimed to restore the original strength and to provide minimum drift capacity. The repair schemes were characterized by the use of; (a) epoxy injections and polymer modified cementitious mortar to seal the cracks and replace spalled concrete; and (b) glass (GFRP) and carbon (CFRP) sheets to enhance the joint performance. The FRP sheets were effectively prevented against possible debonding through the use of fiber anchors. Comparison between responses of specimens before and after repair clearly indicated reasonable restoration in strength, drift capacity, stiffness and cumulative energy dissipation capacity. All specimens failed with delamination of FRP sheets at beam-column joint interfaces. The rapid repair technique developed in this study is recommended for mass upgrading or repair of earthquake damaged beam-column joints.

  18. The Influence of Calcium Chloride Salt Solution on the Transport Properties of Cementitious Materials

    Directory of Open Access Journals (Sweden)

    Yaghoob Farnam

    2015-01-01

    Full Text Available The chemical interaction between calcium chloride (CaCl2 and cementitious binder may alter the transport properties of concrete which are important in predicting the service life of infrastructure elements. This paper presents a series of fluid and gas transport measurements made on cementitious mortars before and after exposure to various solutions with concentrations ranging from 0% to 29.8% CaCl2 by mass. Fluid absorption, oxygen diffusivity, and oxygen permeability were measured on mortar samples prepared using Type I and Type V cements. Three primary factors influence the transport properties of mortar exposed to CaCl2: (1 changes in the degree of saturation, (2 calcium hydroxide leaching, and (3 formation of chemical reaction products (i.e., Friedel’s salt, Kuzel’s salt, and calcium oxychloride. It is shown that an increase in the degree of saturation decreases oxygen permeability. At lower concentrations (~12%, the formation of chemical reaction products (mainly calcium oxychloride is a dominant factor decreasing the fluid and gas transport in concrete.

  19. Experimental Study on Cementitious Composites Embedded with Organic Microcapsules

    Directory of Open Access Journals (Sweden)

    Zhiwei Qian

    2013-09-01

    Full Text Available The recovery behavior for strength and impermeability of cementitious composites embedded with organic microcapsules was investigated in this study. Mortar specimens were formed by mixing the organic microcapsules and a catalyst with cement and sand. The mechanical behaviors of flexural and compression strength were tested. The results showed that strength could increase by up to nine percent with the addition of a small amount of microcapsules and then decrease with an increasing amount of microcapsules. An orthogonal test for investigating the strength recovery rate was designed and implemented for bending and compression using the factors of water/cement ratio, amount of microcapsules, and preloading rate. It is shown that the amount of microcapsules plays a key role in the strength recovery rate. Chloride ion permeability tests were also carried out to investigate the recovery rate and healing effect. The initial damage was obtained by subjecting the specimens to compression. Both the recovery rate and the healing effect were nearly proportional to the amount of microcapsules. The obtained cementitious composites can be seen as self-healing owing to their recovery behavior for both strength and permeability.

  20. Study of sticky rice-lime mortar technology for the restoration of historical masonry construction.

    Science.gov (United States)

    Yang, Fuwei; Zhang, Bingjian; Ma, Qinglin

    2010-06-15

    Replacing or repairing masonry mortar is usually necessary in the restoration of historical constructions, but the selection of a proper mortar is often problematic. An inappropriate choice can lead to failure of the restoration work, and perhaps even further damage. Thus, a thorough understanding of the original mortar technology and the fabrication of appropriate replacement materials are important research goals. Many kinds of materials have been used over the years in masonry mortars, and the technology has gradually evolved from the single-component mortar of ancient times to hybrid versions containing several ingredients. Beginning in 2450 BCE, lime was used as masonry mortar in Europe. In the Roman era, ground volcanic ash, brick powder, and ceramic chip were added to lime mortar, greatly improving performance. Because of its superior properties, the use of this hydraulic (that is, capable of setting underwater) mortar spread, and it was adopted throughout Europe and western Asia. Perhaps because of the absence of natural materials such as volcanic ash, hydraulic mortar technology was not developed in ancient China. However, a special inorganic-organic composite building material, sticky rice-lime mortar, was developed. This technology was extensively used in important buildings, such as tombs, in urban constructions, and even in water conservancy facilities. It may be the first widespread inorganic-organic composite mortar technology in China, or even in the world. In this Account, we discuss the origins, analysis, performance, and utility in historic preservation of sticky rice-lime mortar. Mortar samples from ancient constructions were analyzed by both chemical methods (including the iodine starch test and the acid attack experiment) and instrumental methods (including thermogravimetric differential scanning calorimetry, X-ray diffraction, Fourier transform infrared, and scanning electron microscopy). These analytical results show that the ancient masonry

  1. Using Converter Dust to Produce Low Cost Cementitious Composites by in situ Carbon Nanotube and Nanofiber Synthesis

    Directory of Open Access Journals (Sweden)

    Péter Ludvig

    2011-03-01

    Full Text Available Carbon nanotubes (CNTs and nanofibers (CNFs were synthesized on clinker and silica fume particles in order to create a low cost cementitious nanostructured material. The synthesis was carried out by an in situ chemical vapor deposition (CVD process using converter dust, an industrial byproduct, as iron precursor. The use of these materials reduces the cost, with the objective of application in large-scale nanostructured cement production. The resulting products were analyzed by scanning electron microscopy (SEM, transmission electron microscopy (TEM and thermogravimetric analysis (TGA and were found to be polydisperse in size and to have defective microstructure. Some enhancement in the mechanical behavior of cement mortars was observed due to the addition of these nano-size materials. The contribution of these CNTs/CNFs to the mechanical strength of mortar specimens is similar to that of high quality CNTs incorporated in mortars by physical mixture.

  2. Bioreceptivity evaluation of cementitious materials designed to stimulate biological growth.

    Science.gov (United States)

    Manso, Sandra; De Muynck, Willem; Segura, Ignacio; Aguado, Antonio; Steppe, Kathy; Boon, Nico; De Belie, Nele

    2014-05-15

    Ordinary Portland cement (OPC), the most used binder in construction, presents some disadvantages in terms of pollution (CO2 emissions) and visual impact. For this reason, green roofs and façades have gain considerable attention in the last decade as a way to integrate nature in cities. These systems, however, suffer from high initial and maintenance costs. An alternative strategy to obtain green facades is the direct natural colonisation of the cementitious construction materials constituting the wall, a phenomenon governed by the bioreceptivity of such material. This work aims at assessing the suitability of magnesium phosphate cement (MPC) materials to allow a rapid natural colonisation taking carbonated OPC samples as a reference material. For that, the aggregate size, the w/c ratio and the amount of cement paste of mortars made of both binders were modified. The assessment of the different bioreceptivities was conducted by means of an accelerated algal fouling test. MPC samples exhibited a faster fouling compared to OPC samples, which could be mainly attributed to the lower pH of the MPC binder. In addition to the binder, the fouling rate was governed by the roughness and the porosity of the material. MPC mortar with moderate porosity and roughness appears to be the most feasible material to be used for the development of green concrete walls. PMID:24602907

  3. Fracture propagation in cementitious materials

    DEFF Research Database (Denmark)

    Skocek, Jan

    Mechanical behavior of structures made from cementitious materials has been successfully modeled using non-linear fracture mechanics in recent decades. On the structural scale, an assumption of homogeneity of the material is valid and well established theories can be applied. However, if focus is...... materials needs to be able to take this complexity into account. In this thesis, two frameworks for prediction of strengths of cementitious materials are developed. The rst one relates the strength of materials with aggregates with the properties of the matrix and distribution of aggregates. The second one...

  4. Chemical composition influence of cement based mortars on algal biofouling

    Science.gov (United States)

    Estelle, Dalod; Alexandre, Govin; Philippe, Grosseau; Christine, Lors; René, Guyonnet; Denis, Damidot

    2013-04-01

    The main cause of building-facade biodegradation is the growth of microorganisms. This phenomenon depends on several parameters such as the geographical situation, the environmental conditions and the surface state of the substrate. Several researches have been devoted to the study of the effect of porosity and roughness on the biofouling of stones and mortars. However, none of them have addressed the influence of the mortar chemistry on the microorganism growth kinetic. The main objective of this study is to highlight the influence of the mortar chemistry in relationship with its physical properties on biological weathering. Earlier work showed a good resistance of Calcium Aluminate Cements to biodeterioration by acidogenic bacteria (Thiobacillus) and fungi (Alternaria alternata, Aspergillus Niger and Coniosporium uncinatum). In order to characterize the influence of the mortar chemistry on biofouling, two Portland cements and two alumina cements are used. Among micro-organisms able to grow, green algae are most involved in the aesthetic deterioration of facades. Indeed, they can colonize any type of media and can be a source of nutrients for other micro-organisms such as fungi. The green algae Klebsormidium flaccidum is chosen because of its representativeness. It is indeed the species the most frequently identified and isolated from samples taken on sites. The biofouling kinetic is followed on samples exposed outdoor and on samples tested in a laboratory bench which consists in spraying an algae culture on mortar specimens. The results obtained by in situ trials are compared with the results obtained on the laboratory bench. The microorganism growth kinetic is measured by image analysis. To improve the detection of algae on the surface of the cementitious samples, the raw image is converted in the YIQ color space. Y, I and Q correspond respectively to luminance, in-phase, and quadrature. On the Q channel, the areas covered by algae and the areas of clean mortar

  5. Quantifying moisture transport in cementitious materials using neutron radiography

    Science.gov (United States)

    Lucero, Catherine L.

    A portion of the concrete pavements in the US have recently been observed to have premature joint deterioration. This damage is caused in part by the ingress of fluids, like water, salt water, or deicing salts. The ingress of these fluids can damage concrete when they freeze and expand or can react with the cementitious matrix causing damage. To determine the quality of concrete for assessing potential service life it is often necessary to measure the rate of fluid ingress, or sorptivity. Neutron imaging is a powerful method for quantifying fluid penetration since it can describe where water has penetrated, how quickly it has penetrated and the volume of water in the concrete or mortar. Neutrons are sensitive to light atoms such as hydrogen and thus clearly detect water at high spatial and temporal resolution. It can be used to detect small changes in moisture content and is ideal for monitoring wetting and drying in mortar exposed to various fluids. This study aimed at developing a method to accurately estimate moisture content in mortar. The common practice is to image the material dry as a reference before exposing to fluid and normalizing subsequent images to the reference. The volume of water can then be computed using the Beer-Lambert law. This method can be limiting because it requires exact image alignment between the reference image and all subsequent images. A model of neutron attenuation in a multi-phase cementitious composite was developed to be used in cases where a reference image is not available. The attenuation coefficients for water, un-hydrated cement, and sand were directly calculated from the neutron images. The attenuation coefficient for the hydration products was then back-calculated. The model can estimate the degree of saturation in a mortar with known mixture proportions without using a reference image for calculation. Absorption in mortars exposed to various fluids (i.e., deionized water and calcium chloride solutions) were investigated

  6. Leaching of 90-year old concrete mortar in contact with stagnant water

    International Nuclear Information System (INIS)

    Concrete and other cementitious materials will be used for different purposes in the underground repositories for radioactive waste in the form of spent fuel according to the Swedish concept. Cementitious materials are fundamentally unstable in water and will change properties with time. Thus it is important to know the long-term interaction between the cement-based materials, groundwater and the other materials in the repository that are important for the safety. This report concerns a study of diffusion controlled dissolution of mortar in a case study. In 1906 a water tank was installed in one of the towers in the castle of Uppsala, Sweden. A 20 mm thick layer of concrete mortar was placed on the inner walls of a steel canister which comprised the water tank. It was demolished in 1991 and pieces of the mortar were taken for analysis. The water tank has been refilled periodically with fresh water, which means that the mortar has been leached by drinking water for nearly 85 years. As the steel hinders the penetration of water, diffusion processes must have controlled the leaching. The concrete has been investigated by several methods including thin sections in a polarising microscope, SEM, SEM-EDS, image analysis and chemical analysis. The result shows that the mortar is covered by a thin shell of carbonates presumably reaction products between the cement paste and bicarbonates from the water. Behind the carbonated surface to a depth of around 5-8 mm the mortar shows a distinct porous zone decreasing calcium contents. At the same time there is a relative increase in the sulphate, aluminium and iron concentrations. This indicates that the leaching is fairly complicated and linked to a recrystallisation and redistribution of element. Behind this depth the paste is dense and has a fairly normal composition except for a slight calcium depletion. The SEM analysis shows that there is no distinct portlandite (calcium hydroxide crystals) depletion front. Portlandite is

  7. Leaching of 90-year old concrete mortar in contact with stagnant water

    Energy Technology Data Exchange (ETDEWEB)

    Traegaardh, J.; Lagerblad, B. [Swedish Cement and Concrete Research Inst., Stockholm (Sweden)

    1998-07-01

    Concrete and other cementitious materials will be used for different purposes in the underground repositories for radioactive waste in the form of spent fuel according to the Swedish concept. Cementitious materials are fundamentally unstable in water and will change properties with time. Thus it is important to know the long-term interaction between the cement-based materials, groundwater and the other materials in the repository that are important for the safety. This report concerns a study of diffusion controlled dissolution of mortar in a case study. In 1906 a water tank was installed in one of the towers in the castle of Uppsala, Sweden. A 20 mm thick layer of concrete mortar was placed on the inner walls of a steel canister which comprised the water tank. It was demolished in 1991 and pieces of the mortar were taken for analysis. The water tank has been refilled periodically with fresh water, which means that the mortar has been leached by drinking water for nearly 85 years. As the steel hinders the penetration of water, diffusion processes must have controlled the leaching. The concrete has been investigated by several methods including thin sections in a polarising microscope, SEM, SEM-EDS, image analysis and chemical analysis. The result shows that the mortar is covered by a thin shell of carbonates presumably reaction products between the cement paste and bicarbonates from the water. Behind the carbonated surface to a depth of around 5-8 mm the mortar shows a distinct porous zone decreasing calcium contents. At the same time there is a relative increase in the sulphate, aluminium and iron concentrations. This indicates that the leaching is fairly complicated and linked to a recrystallisation and redistribution of element. Behind this depth the paste is dense and has a fairly normal composition except for a slight calcium depletion. The SEM analysis shows that there is no distinct portlandite (calcium hydroxide crystals) depletion front. Portlandite is

  8. Cement Pastes and Mortars Containing Nitrogen-Doped and Oxygen-Functionalized Multiwalled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Mauricio Martínez-Alanis

    2016-01-01

    Full Text Available Cement pastes and mortars based on ordinary Portland cement containing nitrogen-doped multiwalled carbon nanotubes (MWCNT-Nx or oxygen-functionalized multiwalled carbon nanotubes (MWCNT-Ox are investigated. To incorporate MWCNTs into the cementitious matrix, the as-produced carpets are dispersed over periods of 1 and 2 hours in distilled water at pH levels of 1 and 7. The cement pastes are prepared by adding 0.1 wt% of MWCNTs to cement powder, followed by characterization with SEM and X-ray diffraction (XRD at an early age (first hours of hydration. The mortars are mechanically characterized during the hydration process for a period of 28 days. SEM characterization of cement pastes revealed that the carbon nanotubes are well incorporated in the cementitious matrix, with the hydrated cement grains interconnected by long carbon nanotubes. XRD characterizations demonstrated that, during the hydration of cement pastes, different peaks emerged that were associated with ettringite, hydrated calcium silicate, and calcium hydroxide, among other structures. Results of the compressive strength measurements for mortars simultaneously mixed with MWCNT-Nx and MWCNT-Ox reached an increment of approximately 30% in compressive strength. In addition, density functional theory calculations were performed in nitrogen-doped and oxygen-functionalized carbon nanotubes interacting with a cement grain.

  9. Multiscale characterization of chemical–mechanical interactions between polymer fibers and cementitious matrix

    Energy Technology Data Exchange (ETDEWEB)

    Hernández-Cruz, Daniel; Hargis, Craig W.; Bae, Sungchul; Itty, Pierre A.; Meral, Cagla; Dominowski, Jolee; Radler, Michael J.; Kilcoyne, David A.; Monteiro, Paulo J. M.

    2014-04-01

    Together with a series of mechanical tests, the interactions and potential bonding between polymeric fibers and cementitious materials were studied using scanning transmission X-ray microscopy (STXM) and microtomography (lCT). Experimental results showed that these techniques have great potential to characterize the polymer fiber-hydrated cement-paste matrix interface, as well as differentiating the chemistry of the two components of a bi-polymer (hybrid) fiber the polypropylene core and the ethylene acrylic acid copolymer sheath. Similarly, chemical interactions between the hybrid fiber and the cement hydration products were observed, indicating the chemical bonding between the sheath and the hardened cement paste matrix. Microtomography allowed visualization of the performance of the samples, and the distribution and orientation of the two types of fiber in mortar. Beam flexure tests confirmed improved tensile strength of mixes containing hybrid fibers, and expansion bar tests showed similar reductions in expansion for the polypropylene and hybrid fiber mortar bars.

  10. Properties of Cement Mortar by Use of Hot-Melt Polyamides as Substitute for Fine Aggregate

    Directory of Open Access Journals (Sweden)

    Xiongzhou Yuan

    2015-06-01

    Full Text Available This paper presents an experimental study on use of hot-melt polyamide (HMP to prepare mortar specimens with improved crack healing and engineering properties. The role of HMP in the crack repairing of cement mortar subjected to several rounds of heat treatment was investigated. Compatibility between HMP and hydraulic cement was investigated through X-ray diffraction (XRD and Fourier transform infrared spectra (FTIR technology. Mortar specimens were prepared using standard cement mortar mixes with HMP at 1%, 3% and 5% (by volume for fine aggregate substitute. After curing for 28 days, HMP specimens were subjected to heating at temperature of 160 °C for one, two, and three days and then natural cooling down to ambient temperature. Mechanical and durability properties of the heated HMP mortars were evaluated and compared with those of the corresponding mortars without heating. The microscopic observation of the interfacial transition zone (ITZ of HMP mortar was conducted through environmental scanning electron microscopy (ESEM. Results reveal that incorporation of HMP improves the workability of the HMP/cement binder while leading to decrease in compressive strength and durability. The heated HMP mortars after exposure to heating for one, two, and three days exhibit no obvious change in compressive strength while presenting notable increase in flexural strength and durability compared with the corresponding mortars without heating. The XRD, FTIR and ESEM analyses indicate that no obvious chemical reaction occurs between HMP and hydraulic cement, and thus the self-repairing for interfacial micro-crack in HMP/cement composite system is ascribed to the physical adhesion of HMP to cement matrix rather than the chemical bonding between them.

  11. Traditional mortar represented by sticky rice lime mortar——One of the great inventions in ancient China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The development of traditional lime-based bond in ancient times was reviewed in this paper.It was proved by a lot of historical data that the application of organic materials in inorganic mortar was a sharp-cut characteristic during the developing process of construction gelled materials in ancient China.The important role sticky rice mortar ever played and the historical significance were revealed.Due to the excellent performance,such as high adhesive strength,good toughness,water-proof and so on,traditional mortar represented by sticky rice mortar should be one of the greatest technological contributions of the day in the world.Modern technology was employed in the study of the sticky rice lime mortar and the researching results of our laboratory and some researchers,including the compo-sition and the mechanism of solidification,were also presented.It was found that the sticky rice acted as a matrix of bio-mineralization which affected the microstructure of the calcium carbonate crystal and there was cooperation between sticky rice and calcite produced during the solidifying of the sticky rice mortar,which maybe lead to the excellent performance of the mortar.Because of excellent performance and importance in science,sticky rice mortar can be regarded as one of the greatest inventions in construction history of China.Relative research of sticky mortar will be of importance for the exploring of ancient momentous invention and the repairing of ancient construction.

  12. Traditional mortar represented by sticky rice lime mortar——One of the great inventions in ancient China

    Institute of Scientific and Technical Information of China (English)

    YANG FuWei; ZHANG BingJian; PAN ChangChu; ZENG YuYao

    2009-01-01

    The development of traditional lime-based bond in ancient times was reviewed in this paper. It was proved by a lot of historical data that the application of organic materials in inorganic mortar was a sharp-cut characteristic during the developing process of construction gelled materials in ancient China. The important role sticky rice mortar ever played and the historical significance were revealed. Due to the excellent performance, such as high adhesive strength, good toughness, water-proof and so on, traditional mortar represented by sticky rice mortar should be one of the greatest technological contributions of the day in the world. Modern technology was employed in the study of the sticky rice lime mortar and the researching results of our laboratory and some researchers, including the compo-sition and the mechanism of solidification, were also presented. It was found that the sticky rice acted as a matrix of bio-mineralization which affected the microstructure of the calcium carbonate crystal and there was cooperation between sticky rice and calcite produced during the solidifying of the sticky rice mortar, which maybe lead to the excellent performance of the mortar. Because of excellent performance and importance in science, sticky rice mortar can be regarded as one of the greatest inventions in construction history of China. Relative research of sticky mortar will be of importance for the exploring of ancient momentous invention and the repairing of ancient construction.

  13. Application of Image Analysis Based on SEM and Chemical Mapping on PC Mortars under Sulfate Attack

    Institute of Scientific and Technical Information of China (English)

    YU Cheng; SUN Wei; Scrivener Karen

    2014-01-01

    The degradation mechanisms of cementitious materials exposed to sulfate solutions have been controversial, despite considerable research. In this paper, two methodologies of image analysis based on scanning electron microscope and chemical mapping are used to analyse Portland cement mortars exposed to sodium sulfate solution. The effects of sulfate concentration in solution and water to cement ratio of mortar, which are considered as the most sensitive factors to sulfate attack, are investigated respectively by comparing the macro expansion with microstructure analysis. It is found that the sulfate concentration in pore solution, expressed as sulfate content in C-S-H, plays a critical role on the supersaturation with respect to ettringite and so on the expansion force generated.

  14. Studies of ancient concrete as analogs of cementitious sealing materials for a repository in tuff

    Energy Technology Data Exchange (ETDEWEB)

    Roy, D.M.; Langton, C.A.

    1989-03-01

    The durability of ancient cementitious materials has been investigated to provide data applicable to determining the resistance to weathering of concrete materials for sealing a repository for storage of high-level radioactive waste. Because tuff and volcanic ash are used in the concretes in the vicinity of Rome, the results are especially applicable to a waste repository in tuff. Ancient mortars, plasters, and concretes collected from Rome, Ostia, and Cosa dating to the third century BC show remarkable durability. The aggregates used in the mortars, plasters, and concretes included basic volcanic and pyroclastic rocks (including tuff), terra-cotta, carbonates, sands, and volcanic ash. The matrices of ancient cementitious materials have been characterized and classified into four categories: (1) hydraulic hydrated lime and hydrated lime cements, (2) hydraulic aluminous and ferruginous hydrated lime cements ({plus_minus} siliceous components), (3) pozzolana/hydrated lime cements, and (4) gypsum cements. Most of the materials investigated are in category (3). The materials were characterized to elucidate aspects of the technology that produced them and their response to the environmental exposure throughout their centuries of existence. Their remarkable properties are the result of a combination of chemical, mineralogical, and microstructural factors. Their durability was found to be affected by the matrix mineralogy, particle size, and porosity; aggregate type, grading and proportioning; and the methodology of placement. 30 refs.

  15. Electro-decontamination of cementitious materials

    International Nuclear Information System (INIS)

    The end of operations in nuclear facilities is followed by various decontamination and decommissioning operations. Similar to other electrochemical techniques such as re-alkalinisation and chloride extraction, an electrokinetic remediation process is being developed as a specific method for deeply contaminated concrete structures. Two cements, an ordinary Portland and a 30% slag cement, have been chosen for the conducted work.Mortars and concretes are contaminated by adding non-radioactive cesium in the batch water, cesium being a representative specie of deep encountered contaminants. The conducted experimental and numerical work have focused on three main aspects: characterizing and understanding the cesium transport mechanisms, assessing the electro-remediation process at lab-scale and evaluating the real scale constraints. Using existing knowledge of chloride transport mechanisms, experiments have been conducted to characterize the cesium interactions with cementitious phase and ionic transport in saturated materials. A numerical model have then been developed to describe the cesium transport, taking into account the ionic activity coefficients and interactions with solid phases. Indeed, lab-scale experiments have demonstrated that electro-remediation reduced to 20-50% the initially contained cesium after a three weeks treatment. Treated samples analysis confirmed that deeply diffused cesium is migrating to the surface. Moreover, conducted experiments showed the consistency between the different materials properties, applied currents and decontamination efficiency. A comparative analysis of experiments carried on samples with different shapes, formulations and contamination modes helped assessing and optimizing the process efficiency for various continuous and variable applied currents. Finally, electro-remediation experiments have also been carried on 1m2 concrete slabs. Liquid catholyte and anolyte solutions are replaced by alumina gels and cellulose pastes

  16. Impact of cementitious materials decalcification on transfer properties: application to radioactive waste deep repository

    International Nuclear Information System (INIS)

    Cementitious materials have been selected to compose the engineering barrier system (EBS) of the French radioactive waste deep repository, because of concrete physico-chemical properties: the hydrates of the cementitious matrix and the pH of the pore solution contribute to radionuclides retention; furthermore the compactness of these materials limits elements transport. The confinement capacity of the system has to be assessed while a period at least equivalent to waste activity (up to 100.000 years). His durability was sustained by the evolution of transfer properties in accordance with cementitious materials decalcification, alteration that expresses structure long-term behavior. Then, two degradation modes were carried out, taking into account the different physical and chemical solicitations imposed by the host formation. The first mode, a static one, was an accelerated decalcification test using nitrate ammonium solution. It replicates the EBS alteration dues to underground water. Degradation kinetic was estimated by the amount of calcium leached and the measurement of the calcium hydroxide dissolution front. To evaluate the decalcification impact, samples were characterized before and after degradation in term of microstructure (porosity, pores size distribution) and of transfer properties (diffusivity, gas and water permeability). The influence of cement nature (ordinary Portland cement, blended cement) and aggregates type (lime or siliceous) was observed: experiments were repeated on different mortars mixes. On this occasion, an essential reflection on this test metrology was led. The second mode, a dynamical degradation, was performed with an environmental permeameter. It recreates the EBS solicitations ensured during the re-saturation period, distinguished by the hydraulic pressure imposed by the geologic layer and the waste exothermicity. This apparatus, based on triaxial cell functioning, allows applying on samples pressure drop between 2 and 10 MPa and

  17. Characterisation of historic mortars for conversation diagnosis

    Czech Academy of Sciences Publication Activity Database

    Hauková, Petra; Frankeová, Dita; Slížková, Zuzana

    Glasgow: University of the West of Scotland, 2013 - (Hughes, J.) ISBN 978-1-903978-44-3. [Historic mortars conference /3./. Glasgow (GB), 11.09.2013-13.09.2013] R&D Projects: GA MK(CZ) DF12P01OVV018 Keywords : mortar analysis * mortar characterisation * binder * aggregate Subject RIV: AL - Art, Architecture, Cultural Heritage

  18. Study of 225 deg C thermoluminescent of quartz inclusions extracted from cementitious building materials

    International Nuclear Information System (INIS)

    Incidents of excessive exposure of the population to ionizing radiation could result from a nuclear explosion, the direct exposure to a source theft or loss or an accidental exposure to a source without shielding, for example. During these incidents the victims seldom are using individual protection equipment used in the measurement and control of the doses that were exposed. One of the ways found to the doses assessment due to exposure to this type of accident is the retrospective dosimetry, which determines the excessive doses of radiation exposure, whether chronological or acute, using common materials available in the public domain. The methodology for the application of retrospective dosimetry for thermoluminescence in buildings previously burned, as bricks, it is already well established. Interest is now turning to the use of cementitious building materials such as mortar and concrete to enlarge the scope of application. This study aimed to examine some of these materials and techniques for their possible application in the doses assessment from an accidental irradiation by thermoluminescence. For this the peak about 225 deg C of natural quartz and it extracted of mortar and concrete was certain your stability for the plateau and storage tests, and also the dependence of your luminescent intensity with radiation dose. Presenting a life relatively tans compared enough to that of the accumulation of natural and long radiation sign for dosimetric applications, besides other favorable characteristics, the mortar presented evidence that is possible for retrospective dosimetry through thermoluminescence. (author)

  19. Behaviour of cementitious materials: sulfates and temperature actions

    International Nuclear Information System (INIS)

    The research work presented in this Ph.D. thesis is related to the nuclear waste underground repository concept. Concrete could be used in such a repository, and would be subjected to variations of temperature in presence of sulfate, a situation that could induce expansion of concrete. The research was lead in three parts: an experimental study of the possibility of an internal sulfate attack on mortars; an experimental study and modeling of the chemical equilibriums of the CaO-SiO2-Al2O3-SO3-H2O system; and a modeling of the mechanisms of internal and external sulfate attacks, and the effect of temperature. The results show that mortars can develop expansions after a steam-cure during hydration, but also when a long steam-cure is applied to one-year-old mortars, which is a new point. Ettringite precipitation can be considered as responsible for these expansions. The experimental study of the CaO-SiO2-Al2O3-SO3-H2O system clarified the role of Calcium Silicate Hydrates (C-S-H) on chemical equilibriums of cementitious materials. Sulfate sorption on C-S-H has been studied in detail. The quantity of sulfate bound to the C-S-H mainly depends on the sulfate concentration in solution, on the Ca/Si ratio of the C-S-H and is not significantly influenced by temperature. Aluminium inclusion in the C-S-H seems to be a significant phenomenon. Temperature increases the calcium sulfo-aluminate solubilities and thus increases sulfates concentration in solution. A modeling of the chemical system is proposed. Simulations of external sulfate attack (15 mmol/L of Na2SO4) predict ettringite precipitation at 20 and 85±C. Simulation of internal sulfate attack was performed at a local scale (a hydrated cement grain). An initial inhomogeneity can lead, after a thermal curing at 85±C, to ettringite precipitation in zones originally free from ettringite. This new-formed ettringite could be the origin of the expansions. (author)

  20. Characterization and modeling of major constituent equilibrium chemistry of a blended cement mortar

    Directory of Open Access Journals (Sweden)

    Meeussen J.C.L.

    2013-07-01

    Full Text Available Cementitious materials containing ground granulated iron blast furnace slag and coal combustion fly ash as admixtures are being used extensively for nuclear waste containment applications. Whereas the solid phases of ordinary Portland cement (OPC have been studied in great detail, the chemistry of cement, fly ash and slag blends has received relatively less study. Given that OPC is generally more reactive than slag and fly ash, the mineralogy of OPC provides a logical starting point for describing the major constituent chemistry of blended cement mortars. To this end, a blended cement mortar containing Portland cement, granulated blast furnace slag, fly ash and quartz sand was modeled using a set of solid phases known to form in hydrated OPC with the geochemical speciation solver LeachXS/ORCHESTRA. Comparison of modeling results to the experimentally determined pH-dependent batch leaching concentrations (USEPA Method 1313 indicates that major constituent concentrations are described reasonably well with the Portland cement mineral set; however, modeled and measured aluminum concentrations differ greatly. Scanning electron microscopic analysis of the mortar reveals the presence of Al-rich phyllosilicate minerals heretofore unreported in similar cementitious blends: kaolinite and potassic phyllosilicates similar in composition to illite and muscovite. Whereas the potassic phyllosilicates are present in the quartz sand aggregate, the formation of kaolinite appears to be authigenic. The inclusion of kaolinite in speciation modeling provides a substantially improved description of the release of Al and therefore, suggests that the behavior of phyllosilicate phases may be important for predicting long-term physico-chemical behavior of such systems.

  1. Self-Healing of Microcracks in Engineered Cementitious Composites (ECC) Under a Natural Environment

    OpenAIRE

    Li, Victor C.; Emily N. Herbert

    2013-01-01

    This paper builds on previous self-healing engineered cementitious composites (ECC) research by allowing ECC to heal outdoors, in the natural environment, under random and sometimes extreme environmental conditions. Development of an ECC material that can heal itself in the natural environment could lower infrastructure maintenance costs and allow for more sustainable development in the future by increasing service life and decreasing the amount of resources and energy needed for repairs. Det...

  2. Service life prediction and cementitious composites

    DEFF Research Database (Denmark)

    Stoklund Larsen, E.

    The present Ph.D.thesis describes and discusses the applicability of a systematic methodology recommended by CIB W80/RILEM-PSL for sevice life prediction. The report describes the most important inherent and environmental factors affecting the service life of structures of cementitious composites....... On the basis of this discription of factors and experience from a test programme described in SBI Report 222, Service life prediction and fibre reinforced cementitious composites, the applicabillity of the CIB/RILEM methodology is discussed....

  3. COMPRESSIVE STRENGTH TESTING OF EARTH MORTARS

    Directory of Open Access Journals (Sweden)

    Givanildo Alves Azeredo

    2007-06-01

    Full Text Available This paper discusses the compressive strength of earth mortars. The goal is to use these mortars for masonry construction. Although it is necessary to study the whole masonry behaviour, the scope of this paper refers to the mortar only, without taking into account the blocks. As with other masonry units, compressive strength is a basic measure of quality for masonry mortars. However, there is a great variety of methodology for determining their parameters and properties, such as different samples geometry, the way strains are measured and also the platen restraint effect adopted. The present paper outlines certain experimental devices used to determine compressive strength of earth mortars and tries to show their influence on the properties determined. Proposals for the future development of testing earth mortars are outlined.

  4. Temperature effect on the poro-mechanical or hydraulic behaviour of a carbonated rock and a mortar: experimental studies

    International Nuclear Information System (INIS)

    The main objective of this study is to evaluate the temperature effect on the hydraulic and poro-mechanical behaviour of a limestone. Many experimental tests (porosity and permeability measurements, uniaxial and hydrostatic compressions tests) were carried out in order to study the thermal treatments effect and so the thermal microcracking effect on rock behaviour. Moreover, an experimental device for permeability measurements under high temperatures (until 200 C) was realized. This experimental device permitted to study the permeability variation of the limestone under thermal stresses. Finally, the behaviour of cementitious materials was studied; the temperature effect on the permeability of a mortar was examined. (author)

  5. Using Neutron Radiography to Quantify Water Transport and the Degree of Saturation in Entrained Air Cement Based Mortar

    Science.gov (United States)

    Lucero, Catherine L.; Bentz, Dale P.; Hussey, Daniel S.; Jacobson, David L.; Weiss, W. Jason

    Air entrainment is commonly added to concrete to help in reducing the potential for freeze thaw damage. It is hypothesized that the entrained air voids remain unsaturated or partially saturated long after the smaller pores fill with water. Small gel and capillary pores in the cement matrix fill quickly on exposure to water, but larger pores (entrapped and entrained air voids) require longer times or other methods to achieve saturation. As such, it is important to quantitatively determine the water content and degree of saturation in air entrained cementitious materials. In order to further investigate properties of cement-based mortar, a model based on Beer's Law has been developed to interpret neutron radiographs. This model is a powerful tool for analyzing images acquired from neutron radiography. A mortar with a known volume of aggregate, water to cement ratio and degree of hydration can be imaged and the degree of saturation can be estimated.

  6. Durability of expanded polystyrene mortars

    OpenAIRE

    Ferrándiz Mas, Verónica; García Alcocel, Eva María

    2013-01-01

    The influence of the addition of various types and various concentrations of expanded polystyrene foam (both commercial and recycled) on the durability of Portland cement mortars is studied. In particular, the microstructure is studied utilizing the following methods: capillary absorption of water, mercury intrusion porosimetry, impedance spectroscopy and open porosity. In addition, the effects of heat cycles and freeze–thaw cycles on compressive strength are examined. Scanning electron micro...

  7. Lime mortars with natural fibres

    Czech Academy of Sciences Publication Activity Database

    Drdácký, Miloš; Michoinová, D.

    Varšava : ZTUREK, 2003 - (Brandt, A.; Li, V.; Marshall, I.), s. 523-532 ISBN 1-85573-769-8. [International Symposium of Brittle matrix /7./. Varšava (PL), 13.10.2003-15.10.2003] R&D Projects: GA MK PK00P04OPP015 Institutional research plan: CEZ:AV0Z2071913 Keywords : lime mortar * natural fibres * experimental research Subject RIV: JM - Building Engineering

  8. Green and early age compressive strength of extruded cement mortar monitored with compression tests and ultrasonic techniques

    International Nuclear Information System (INIS)

    Knowledge about the early age compressive strength development of cementitious materials is an important factor for the progress and safety of many construction projects. This paper uses cylindrical mortar specimens produced with a ram extruder to investigate the transition of the mortar from plastic and deformable to hardened state. In addition, wave transmission and reflection measurements with P- and S-waves were conducted to obtain further information about the microstructural changes during the setting and hardening process. The experiments have shown that uniaxial compression tests conducted on extruded mortar cylinders are a useful tool to evaluate the green strength as well as the initiation and further development of the compressive strength of the tested material. The propagation of P-waves was found to be indicative of the internal structure of the tested mortars as influenced, for example, by the addition of fine clay particles. S-waves used in transmission and reflection mode proved to be sensitive to the inter-particle bonding caused by the cement hydration and expressed by an increase in compressive strength

  9. Hydration mechanism of a cementitious material prepared with Si-Mn slag

    Science.gov (United States)

    Zhang, Xu-Fang; Ni, Wen; Wu, Jun-Yu; Zhu, Li-Ping

    2011-04-01

    A cementitious material was prepared by mixing 80wt% Si-Mn slag powder, 10wt% lime, and 10wt% anhydrite. The compressive strength of mortar samples reaches 51.48 MPa after 28 d curing. The analyses of X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that much ettringite is formed in the sample cured for 3 d, and C-S-H gel increases rapidly during subsequent curing. Nuclear magnetic resonance (NMR) analysis of 29Si and 27Al and infrared spectroscopy (IR) analysis show that aluminum decomposition from tetrahedral network of the slag glass and its subsequent migration and re-combination play an important role in the process of hydration and strength development of the samples.

  10. Electrokinetic decontamination of porous media. Experimental study and modeling of the cesium transport through cementitious materials

    International Nuclear Information System (INIS)

    The aim of this work is to study the nuclear decontamination of cementitious materials by an electrokinetic method. Special attention is given to the understanding of the mechanisms leading to the removal of radioelements from the material. First, a bibliographic research allowed us to reduce the study to a normalized mortar and to cesium ions. This choice was confirmed by the experimental study of interactions between the contaminant and the material. Next, the efficiency of the electrokinetic decontamination was experimentally shown in laboratory conditions and electromigration was identified as the main transport phenomenon. Then, a numerical model was implemented in order to describe the ionic transport by electromigration. The results obtained were compared to experiments. Finally, some applications and developments of the electrokinetic process were proposed. (author)

  11. Rendering mortars in Medina Azahara, Part I: Material characterization and alteration process

    Directory of Open Access Journals (Sweden)

    Blanco-Varela, M. T.

    1997-03-01

    Full Text Available Rendering mortars, which are still exposed to the open air on some of the walls of Medina Azahara, are studied and characterized in this work. Some repairing mortars used in different previous restorations are also characterized. Those rendering mortars are of different make considering the composition of their binder: lime, gypsum and mixed lime/ gypsum. Repairing mortars used in previous interventions are made of lime, excepting for a portland cement used by Félix Hernández in the restoration of one of the rooms back in the 50's. Biological colonization is the main cause of decay in lime mortars, while in mortars made of gypsum, decay is a result of the solubilizating action of rain water.

    En este trabajo se analizan y caracterizan los revocos que, todavía hoy, permanecen sobre algunos paramentos de los muros de la ciudad de Medina Azahara, expuestos a la intemperie. También se caracterizan algunos de los molleros de reparación aplicados en las distintas restauraciones de los revocos. Los revocos están formados por tres clase de morteros, atendiendo a la composición de su ligante: de cal, de yeso y bastardos de cal y yeso. Los morteros de reparación que se han utilizado son de cal, a excepción del utilizado en la restauración de Félix Hernández (década de 1950, en una de las salas, que es de cemento portland. La colonización biológica es la principal causa de deterioro de los morteros de cal, en tanto que la solubilización por las aguas de lluvia lo es en los morteros que contienen yeso.

  12. Simple Analysis of Historical Lime Mortars

    Science.gov (United States)

    Pires, Joa~o

    2015-01-01

    A laboratory experiment is described in which a simple characterization of a historical lime mortar is made by the determination of its approximate composition by a gravimetric method. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) are also used for the qualitative characterization of the lime mortar components. These…

  13. Ancient gypsum mortars from Cyprus: characterization and reinvention

    Science.gov (United States)

    Theodoridou, M.; Ioannou, I.

    2012-04-01

    confirms the phenomena of crystallisation and recrystallisation closed to the exposed surfaces due to long-term weathering. As anticipated, the results of this study have proven useful in reinventing gypsum-based materials based on the production technology of the past and the use of local raw materials. It is worth noting that gypsum is a widely available mineral in Cyprus due to the extensive evaporite deposits on the island. In the mortars designed and produced in the laboratory, ratios of binder to aggregates were based on the results of the analysed ancient samples. Gypsum and lime based materials were used in different proportions both as binder and aggregates. The new mixtures were tested in fresh and dry conditions at 7, 28, 56 and 90 days after their production. The results indicated higher mechanical strengths (7.6-9.6 MPa) when only gypsum based materials were used both as binder and aggregates. Porosity and average pore diameter tended to increase as the percentage of calcite increased in the mixtures. The variability of the results enhances the possibility of selecting the appropriate repair mortar depending on the nature of the material which may demand a conservation treatment.

  14. Long-term alteration of cementitious materials

    International Nuclear Information System (INIS)

    Long-term alteration of cementitious materials in the geological condition has been discussed for the safety assessment of radioactive waste disposal. This paper describes the status of understanding long-term chemical alteration of cement, by reviewing some of our investigations on this issue in which we developed a thermodynamic incongruent C-S-H dissolution/precipitation model and a reactive transport calculation code. Alteration of C-S-H gel in a saline groundwater and the change of chemical barrier performance of cementitious materials due to the alteration are also discussed. Some key issues to be discussed further are given and suggested for the future studies on the long-term alteration of cementitious materials in the repository environment. (author)

  15. Characterizing saturated mass transport in fractured cementitious materials

    Science.gov (United States)

    Akhavan, Alireza

    Concrete, when designed and constructed properly, is a durable material. However in aggressive environments concrete is prone to gradual deterioration which is due to penetration of water and aggressive agents (e.g., chloride ions) into concrete. As such, the rate of mass transport is the primary factor, controlling the durability of cementitious materials. Some level of cracking is inevitable in concrete due to brittle nature of the material. While mass transport can occur through concrete’s porous matrix, cracks can significantly accelerate the rate of mass transport and effectively influence the service life of concrete structures. To allow concrete service life prediction models to correctly account for the effect of cracks on concrete durability, mass transport thru cracks must be characterized. In this study, transport properties of cracks are measured to quantify the saturated hydraulic permeability and diffusion coefficient of cracks as a function of crack geometry (i.e.; crack width, crack tortuosity and crack wall roughness). Saturated permeability and diffusion coefficient of cracks are measured by constant head permeability test, electrical migration test, and electrical impedance spectroscopy. Plain and fiber reinforced cement paste and mortar as well as simulated crack samples are tested. The results of permeability test showed that the permeability of a crack is a function of crack width squared and can be predicted using Louis formula when crack tortuosity and surface roughness of the crack walls are accounted for. The results of the migration and impedance tests showed that the diffusion coefficient of the crack is not dependent on the crack width, but is primarily a function of volume fraction of cracks. The only parameter that is changing with the crack width is the crack connectivity. Crack connectivity was found to be linearly dependent on crack width for small crack and constant for large cracks (i.e.; approximately larger than 80 µm). The

  16. Use of flexible engineered cementitious composite in buildings

    International Nuclear Information System (INIS)

    This article describes the applications and benefits of a recently developed smart building material namely Engineered cementitious composite (ECC), also known as flexible or bendable concrete. Conventional concretes have a strain capacity of only 0.1 percent and are highly brittle and rigid. This lack of bend ability is a major cause of failure under strain and has been a pushing factor in the development of an elegant material which is capable to exhibit an enhanced flexibility. An ECC has a strain capacity of more than 3 percent and thus acts more like a ductile metal rather than like a brittle glass. The aim of this paper is to highlight a probable success of ECC in terms of industrial and commercial use in Pakistan. With the introduction of flexible concrete in building technology, it is likely to have safer and more durable construction. The material is expected to display reduced detrimental impacts on the natural environment. A bendable concrete is composed of all the ingredients of a traditional concrete minus coarse aggregates or crushed stones and is reinforced with micro mechanically designed polymer fibers. The mechanism of action of the micro-polymeric fibers in concrete has also been emphasized. The principles of mix designs of the mortar incorporating fibers to make an ECC have also been explained. It has also been mentioned in detail as how this technology can be used to enhance the flexibility of some modern concrete types like flowing concrete, self-compacting concrete, and lightweight concrete. ECC is a green construction material. The possible benefits like environment friendliness, cost effectiveness, and durability have been also been elucidated in the paper. (author)

  17. Methyl methacrylate as a healing agent for self-healing cementitious materials

    International Nuclear Information System (INIS)

    Different types of healing agents have already been tested on their efficiency for use in self-healing cementitious materials. Generally, commercial healing agents are used while their properties are adjusted for manual crack repair and not for autonomous crack healing. Consequently, the amount of regain in properties due to self-healing of cracks is limited. In this research, a methyl methacrylate (MMA)-based healing agent was developed specifically for use in self-healing cementitious materials. Various parameters were optimized including the viscosity, curing time, strength, etc. After the desired properties were obtained, the healing agent was encapsulated and screened for its self-healing efficiency. The decrease in water permeability due to autonomous crack healing using MMA as a healing agent was similar to the results obtained for manually healed cracks. First results seem promising: however, further research needs to be undertaken in order to obtain an optimal healing agent ready for use in practice

  18. The Effectiveness of High Quality Supplementary Cementitious Materials for Mitigating ASR Expansion in Concrete with High Alkali Content

    Directory of Open Access Journals (Sweden)

    I. Prasetia

    2015-10-01

    Full Text Available Alkali silica reaction (ASR is influenced by external factors such as the surrounding environment of high alkalinity. Countries with cold climate have a high probability to be exposed to high concentrations of NaCl solution by the deicing salt. This condition will lead to serious ASR problems in concrete, if the aggregates contain reactive silica. The main research work in this paper is to investigate the effect of 15% replacement ratio of high quality fine fly ash (FA15% and 42% replacement ratio of blast furnace slag (BFS42% on the ASR mitigation in concrete with different alkali amount inside the pore solution. The experiments were conducted according to the accelerated mortar bars experiment following the JIS A1146 mortar bar test method. In addition, post-analysis such as observation of ASR gel formation by the Uranyl Acetate Fluorescence Method and observation of thin sections using a Polarizing Microscope were also conducted. The mortar bar tests show a very good mitigation effect of supplementary cementitious materials (SCMs. The results show that only small ASR expansions, which can be categorized as “innocuous”, occurred for specimens with 1.2% Na2Oeq using FA15% and BFS42%. However, larger alkali amount inside the system will require more SCMs amount.

  19. Strontium Uptake by Cementitious Materials

    Energy Technology Data Exchange (ETDEWEB)

    Wieland,E.; Tits, J.; Kunz, D.; Dahn, R.

    2008-01-01

    Wet chemistry experiments and X-ray absorption fine structure (XAFS) measurements were carried out to investigate the immobilization of nonradioactive Sr and 85Sr in calcite-free and calcite-containing Portland cement. The partitioning of pristine Sr between hardened cement paste (HCP) and pore solution, and the uptake of 85Sr and nonradioactive Sr were investigated in batch-type sorption/desorption experiments. Sr uptake by HCP was found to be fast and nearly linear for both cements, indicating that differences in the compositions of the two cements have no influence on Sr binding. The partitioning of pristine Sr bound in the cement matrix and 85Sr between HCP and pore solution could be modeled in terms of a reversible sorption process using similar Kd values. These findings allow 85Sr uptake to be interpreted in terms of an isotopic exchange process with pristine Sr. Sr K-edge EXAFS measurements on Sr doped HCP and calcium silicate hydrate (C-S-H) samples reveal no significant differences in the local coordination environments of pristine Sr and Sr bound to the cement matrix upon sorption. The first coordination sphere consists of five to six oxygen atoms located at a distance of about 2.6 Angstroms, which corresponds to Sr-O distances in the hydration sphere of Sr2+ in alkaline solution. Sr binds to the cement matrix via two bridging oxygen atoms located at a distance of about 3.6 Angstroms. No further neighboring atoms could be detected, indicating that Sr is taken up as a partially hydrated species by HCP. Wet chemistry and spectroscopic data further indicate that Sr binding to C-S-H phases is likely to be the controlling uptake mechanism in the cement matrix, which allows Sr uptake by HCP to be predicted based on a Ca-Sr ion exchange model previously developed for Sr binding to C-S-H phases. The latter finding suggests that long-term predictions of Sr immobilization in the cementitious near field of repositories for radioactive waste can be based on a

  20. ASSESSMENT OF FINE RECYCLED AGGREGATES IN MORTAR

    OpenAIRE

    Feys, Charles; Joseph, Miquel; Boehme, Luc; Zhang, Yunlian

    2016-01-01

    In this study, the influence of fine recycled concrete aggregates as replacement for sand in mortar and the use as cement replacement and filler is investigated. Mortar with fine recycled aggregates is examined on its mechanical and physical properties. The samples are also examined on a microscopic scale. The fine recycled concrete aggregates are made with one-year old concrete made in the laboratory. Fine recycled aggregates (FRCA) are added as a cement replacement (0 %, 10 %...

  1. Modeling of Degradation Processes in Historical Mortars

    OpenAIRE

    Sýkora, J

    2014-01-01

    The aim of presented paper is modeling of degradation processes in historical mortars exposed to moisture impact during freezing. Internal damage caused by ice crystallization in pores is one of the most important factors limiting the service life of historical structures. Coupling the transport processes with the mechanical part will allow us to address the impact of moisture on the durability, strength and stiffness of mortars. This should be accomplished with the help of a complex thermo-h...

  2. Comparative experimental study of dynamic compressive strength of mortar with glass and basalt fibres

    Science.gov (United States)

    Kruszka, Leopold; Moćko, Wojciech; Fenu, Luigi; Cadoni, Ezio

    2015-09-01

    Specimen reinforced with glass and basalt fibers were prepared using Standard Portland cement (CEM I, 52.5 R as prescribed by EN 197-1) and standard sand, in accordance with EN 196-1. From this cementitious mixture, a reference cement mortar without fibers was first prepared. Compressive strength, modulus of elasticity, and mod of fracture were determined for all specimens. Static and dynamic properties were investigated using Instron testing machine and split Hopkinson pressure bar, respectively. Content of the glass fibers in the mortar does not influence the fracture stress at static loading conditions in a clearly observed way. Moreover at dynamic range 5% content of the fiber results in a significant drop of fracture stress. Analysis of the basalt fibers influence on the fracture stress shows that optimal content of this reinforcement is equal to 3% for both static and dynamic loading conditions. Further increase of the fiber share gives the opposite effect, i.e. drop of the fracture stress.

  3. On the relevance of volume increase for the length changes of mortar bars in sulfate solutions

    International Nuclear Information System (INIS)

    The ingress of sulfate ions into cementitious materials leads to the formation of ettringite, gypsum and other phases. The increase in solid volume through the formation of these phases is often assumed to be the only reason for expansion. In this paper we systematically compare the volume increase predicted by thermodynamic modeling to macroscopic expansion for mortars made with CEM I in different sulfate solutions and for mortars made with a range of blended cements in sodium sulfate solution. It is shown that the length changes cannot be explained by simple volume increase alone. A more plausible explanation of expansion lies in the theory of crystallization pressure, in which crystals forming from a supersaturated solution may exert pressure on their surroundings. It is observed that expansion occurs in systems where thermodynamic modeling predicts the co-existence of ettringite with gypsum. In such a case, if monosulfate and gypsum are both present locally, the solution can be highly supersaturated with respect to ettringite, whose formation in confined conditions (such as within C–S–H) can then exert expansive forces

  4. On the relevance of volume increase for the length changes of mortar bars in sulfate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kunther, Wolfgang, E-mail: wkunther@googlemail.com [Empa, Laboratory for Concrete and Construction Chemistry, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Lothenbach, Barbara [Empa, Laboratory for Concrete and Construction Chemistry, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Scrivener, Karen L. [EPFL, Laboratory of Construction Materials, CH-1015 Lausanne (Switzerland)

    2013-04-01

    The ingress of sulfate ions into cementitious materials leads to the formation of ettringite, gypsum and other phases. The increase in solid volume through the formation of these phases is often assumed to be the only reason for expansion. In this paper we systematically compare the volume increase predicted by thermodynamic modeling to macroscopic expansion for mortars made with CEM I in different sulfate solutions and for mortars made with a range of blended cements in sodium sulfate solution. It is shown that the length changes cannot be explained by simple volume increase alone. A more plausible explanation of expansion lies in the theory of crystallization pressure, in which crystals forming from a supersaturated solution may exert pressure on their surroundings. It is observed that expansion occurs in systems where thermodynamic modeling predicts the co-existence of ettringite with gypsum. In such a case, if monosulfate and gypsum are both present locally, the solution can be highly supersaturated with respect to ettringite, whose formation in confined conditions (such as within C–S–H) can then exert expansive forces.

  5. Comparative experimental study of dynamic compressive strength of mortar with glass and basalt fibres

    Directory of Open Access Journals (Sweden)

    Kruszka Leopold

    2015-01-01

    Full Text Available Specimen reinforced with glass and basalt fibers were prepared using Standard Portland cement (CEM I, 52.5 R as prescribed by EN 197-1 and standard sand, in accordance with EN 196-1. From this cementitious mixture, a reference cement mortar without fibers was first prepared. Compressive strength, modulus of elasticity, and mod of fracture were determined for all specimens. Static and dynamic properties were investigated using Instron testing machine and split Hopkinson pressure bar, respectively. Content of the glass fibers in the mortar does not influence the fracture stress at static loading conditions in a clearly observed way. Moreover at dynamic range 5% content of the fiber results in a significant drop of fracture stress. Analysis of the basalt fibers influence on the fracture stress shows that optimal content of this reinforcement is equal to 3% for both static and dynamic loading conditions. Further increase of the fiber share gives the opposite effect, i.e. drop of the fracture stress.

  6. Experimental study of hot mixed mortars in comparison with lime putty and hydrate mortars

    Czech Academy of Sciences Publication Activity Database

    Válek, Jan; Matas, Tomáš

    Vol. 7. Dordrecht : Springer, 2012 - (Válek, J.; Hughes, J.; Groot, J.), s. 269-281 ISBN 978-94-007-4634-3 R&D Projects: GA MŠk(CZ) LA09008 Institutional support: RVO:68378297 Keywords : hot mixed mortars * lime putty * hydrate mortars Subject RIV: AL - Art, Architecture, Cultural Heritage

  7. Physico-chemical characterization of mortars as a tool in studying specific hydraulic components: application to the study of ancient Naxos aqueduct

    Science.gov (United States)

    Maravelaki-Kalaitzaki, P.; Galanos, A.; Doganis, I.; Kallithrakas-Kontos, N.

    2011-07-01

    Mortars and plasters from the ancient aqueduct on the island of Naxos, Greece, were studied with regard to mineralogical and chemical composition, grain size distribution, raw materials and hydraulic properties, in order to assess their characteristics and design compatible repair mortars. The authentic materials contained lime, crushed-brick, siliceous and calcitic aggregates, in different proportions according to mortar type. Crushed-bricks fired at low temperatures and lightweight volcanic aggregates contained amorphous phases, which upon reaction with lime yielded hydraulic components capable of protecting the construction from the continuous presence of water. Hydraulic calcium silicate/aluminate hydrates, the proportions and the perfect packing of the raw materials, along with the diligent application justify the longevity and durability of the studied samples. The hydraulic properties of samples were pointed out through (a) the well-established CO2/H2O ratio derived from the thermogravimetric analysis and (b) by introducing two powerful indices issued from the chemical analysis, namely CaOhydr and soluble SiO2 hydr. These indices improved the clustering of hydraulic mortars and provided better correlation between mortars, plasters and their binders. By comparing grain size distribution and hydraulicity indices it was possible to distinguish among the construction phases. Based on this study, repair mortars were formulated by hydraulic lime, siliceous sand, calcareous and crushed-brick aggregates, with the optimal water content, ensuring optimum workability and compatible appearance with the authentic ones.

  8. Method for characterization of the redox condition of cementitious materials

    Energy Technology Data Exchange (ETDEWEB)

    Almond, Philip M.; Langton, Christine A.; Stefanko, David B.

    2015-12-22

    Disclosed are methods for determining the redox condition of cementitious materials. The methods are leaching methods that utilize an in situ redox indicator that is present in the cementitious materials as formed. The in situ redox indicator leaches from cementitious material and, when the leaching process is carried out under anaerobic conditions can be utilized to determine the redox condition of the material. The in situ redox indicator can exhibit distinct characteristics in the leachate depending upon the redox condition of the indicator.

  9. Nanoscale characterization of engineered cementitious composites (ECC)

    International Nuclear Information System (INIS)

    Engineered cementitious composites (ECC) are ultra-ductile fiber-reinforced cementitious composites. The nanoscale chemical and mechanical properties of three ECC formulae (one standard formula, and two containing nanomaterial additives) were studied using nanoindentation, electron microscopy, and energy dispersive spectroscopy. Nanoindentation results highlight the difference in modulus between bulk matrix (∼ 30 GPa) and matrix/fiber interfacial transition zones as well as between matrix and unreacted fly ash (∼ 20 GPa). The addition of carbon black or carbon nanotubes produced little variation in moduli when compared to standard M45-ECC. The indents were observed by electron microscopy; no trace of the carbon black particles could be found, but nanotubes, including nanotubes bridging cracks, were easily located in ultrafine cracks near PVA fibers. Elemental analysis failed to show a correlation between modulus and chemical composition, implying that factors such as porosity have more of an effect on mechanical properties than elemental composition.

  10. Final Report - Assessment of Potential Phosphate Ion-Cementitious Materials Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Naus, Dan J [ORNL; Mattus, Catherine H [ORNL; Dole, Leslie Robert [ORNL

    2007-06-01

    The objectives of this limited study were to: (1) review the potential for degradation of cementitious materials due to exposure to high concentrations of phosphate ions; (2) provide an improved understanding of any significant factors that may lead to a requirement to establish exposure limits for concrete structures exposed to soils or ground waters containing high levels of phosphate ions; (3) recommend, as appropriate, whether a limitation on phosphate ion concentration in soils or ground water is required to avoid degradation of concrete structures; and (4) provide a "primer" on factors that can affect the durability of concrete materials and structures in nuclear power plants. An assessment of the potential effects of phosphate ions on cementitious materials was made through a review of the literature, contacts with concrete research personnel, and conduct of a "bench-scale" laboratory investigation. Results of these activities indicate that: no harmful interactions occur between phosphates and cementitious materials unless phosphates are present in the form of phosphoric acid; phosphates have been incorporated into concrete as set retarders, and phosphate cements have been used for infrastructure repair; no standards or guidelines exist pertaining to applications of reinforced concrete structures in high-phosphate environments; interactions of phosphate ions and cementitious materials has not been a concern of the research community; and laboratory results indicate similar performance of specimens cured in phosphate solutions and those cured in a calcium hydroxide solution after exposure periods of up to eighteen months. Relative to the "primer," a separate NUREG report has been prepared that provides a review of pertinent factors that can affect the durability of nuclear power plant reinforced concrete structures.

  11. Final Report - Assessment of Potential Phosphate Ion-Cementitious Materials Interactions

    International Nuclear Information System (INIS)

    The objectives of this limited study were to: (1) review the potential for degradation of cementitious materials due to exposure to high concentrations of phosphate ions; (2) provide an improved understanding of any significant factors that may lead to a requirement to establish exposure limits for concrete structures exposed to soils or ground waters containing high levels of phosphate ions; (3) recommend, as appropriate, whether a limitation on phosphate ion concentration in soils or ground water is required to avoid degradation of concrete structures; and (4) provide a 'primer' on factors that can affect the durability of concrete materials and structures in nuclear power plants. An assessment of the potential effects of phosphate ions on cementitious materials was made through a review of the literature, contacts with concrete research personnel, and conduct of a 'bench-scale' laboratory investigation. Results of these activities indicate that: no harmful interactions occur between phosphates and cementitious materials unless phosphates are present in the form of phosphoric acid; phosphates have been incorporated into concrete as set retarders, and phosphate cements have been used for infrastructure repair; no standards or guidelines exist pertaining to applications of reinforced concrete structures in high-phosphate environments; interactions of phosphate ions and cementitious materials has not been a concern of the research community; and laboratory results indicate similar performance of specimens cured in phosphate solutions and those cured in a calcium hydroxide solution after exposure periods of up to eighteen months. Relative to the 'primer,' a separate NUREG report has been prepared that provides a review of pertinent factors that can affect the durability of nuclear power plant reinforced concrete structures

  12. Physical characterization methods for supplementary cementitious materials

    OpenAIRE

    Arvaniti, Eleni; Juenger, Maria; Bernal, Susan; Duchesne, Josée; Courard, Luc; Leroy, Sophie; Provis, John; Klemm, Agnieska; De Belie, Nele

    2015-01-01

    The main supplementary cementitious materials (SCMs) that are used today are industrial by-products. In most cases the quality of these materials cannot be controlled during their production, resulting in materials with varied characteristics. The adequate physical characterization of SCMs is important to better predict their performance and optimize their use in concretes production. There are standardized methods used to determine the particle characteristics for Portland cements that are u...

  13. The aggressiveness of pig slurry to cement mortars

    OpenAIRE

    Massana Guitart, Jordi; Guerrero Bustos, Ana; Antón Fuentes, Rebeca; Garcimartin Molina, Miguel Angel; Sanchez Espinosa, Elvira

    2013-01-01

    The aim was to measure the behaviour of various mortars employed in livestock media in central Spain and to analyse the aggressiveness of pig slurry to cement blended with fly ash mortars. To achieve this, mortar specimens were immersed in ponds storing pig slurry. Mortar specimens, of 40 ? 40 ? 160 mm, were made from four types of cement commonly used and recommended for rural areas. The types were a sulphate-resistant Portland cement and three cements blended in different proportions with ...

  14. High-Performance Grouting Mortar Based on Mineral Admixtures

    OpenAIRE

    2015-01-01

    A study on high-performance grouting mortar is reported. The common mortar was modified by mineral admixtures such as gypsum, bauxite, and alunite. The effects of mineral admixtures on the fluidity, setting time, expansion, strength, and other properties of mortar were evaluated experimentally. The microstructure of the modified mortar was characterized by X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry. Moreover, the expansive performance and strength of th...

  15. MORTAR FINITE VOLUME METHOD WITH ADINI ELEMENT FOR BIHARMONIC PROBLEM

    Institute of Scientific and Technical Information of China (English)

    Chun-jia Bi; Li-kang Li

    2004-01-01

    In this paper, we construct and analyse a mortar finite volume method for the dis-cretization for the biharmonic problem in R2. This method is based on the mortar-type Adini nonconforming finite element spaces. The optimal order H2-seminorm error estimate between the exact solution and the mortar Adini finite volume solution of the biharmonic equation is established.

  16. Properties of Mortar Incorporating Iron Slag

    Directory of Open Access Journals (Sweden)

    Tamara HUMAM

    2013-11-01

    Full Text Available In the present study effects of replacement of fine aggregate (sand with high percentages of iron slag on the properties of Mortar. Cement mortars of mix proportion 1:3 with incorporating various percentage of iron slag was designed. Fine aggregate were replace with five percentage of iron slag. The percentages of replacements were 0, 10, 20, 30, and 40% by weight of fine aggregate. Tests were performed for compressive strength, split tensile strength, sulphate resistance, Rapid Chloride Permeability Test. Test for all replacement levels of iron slag at different curing periods (7, 28, 56 days . Test result indicates that inclusion of iron slag as partial replacement with fine aggregate enhances the properties of Mortar.

  17. Gas evolution behavior of aluminum in mortar

    International Nuclear Information System (INIS)

    As a part of study of leaching behavior for solidified dry low level radioactive waste, gas evolution behavior of aluminum in mortar was investigated, and a plan of our research was proposed. The effect of pH on corrosion rate of aluminum, corrosion product, time dependency of corrosion rate of aluminum in mortar, change of corrosion mechanism, the effects of Na, Ca and Cl ions on corrosion rate of aluminum in mortar and corrosion behavior of aluminum when aluminum was used as sacrificed anode in reinforced concrete were previously clarified. Study of the effects of environmental factors such as pH, kind of ions and temperature on gas evolution behavior of aluminum and the effect of aluminum/carbon steel surface ratio no gas evolution behavior of aluminum were planed. (author). 75 refs

  18. Evaluation of Lime for Use in Mortar

    Directory of Open Access Journals (Sweden)

    Naktode P.L.

    2014-02-01

    Full Text Available Lime has been used in India as material of construction from very ancient days. The manner in which lime structures about 2000 years old have withstood the ravages of time bear irrefutable evidence to the durability of lime mortars. Lime mortars were the mortars of very recent years – used until the twentieth century. Although they are almost forgotten today, they still remain a viable and important construction method [1]. There is something about this material that remains just as valuable today as it was 150 years ago [2]. The lime belt of Vidarbha area is not of industrial grade. To use for construction purpose it needs some improvement and alteration in the ingredients. This calls the development of an alternative approach to make it suitable for construction in large extent. Keywords:

  19. Innovative methodology for comprehensive utilization of iron ore tailings: part 2: The residues after iron recovery from iron ore tailings to prepare cementitious material.

    Science.gov (United States)

    Li, Chao; Sun, Henghu; Yi, Zhonglai; Li, Longtu

    2010-02-15

    In order to comprehensive utilization of iron ore tailings, this experimental research was to investigate the possibility of using the residues after iron recovery from iron ore tailings as raw materials for the preparation of cementitious material, abbreviated as TSC, including analyses of its mechanical properties, physical properties and hydration products. The TSC1 was prepared by blending 30% the residues, 34% blast-furnace slag, 30% clinker and 6% gypsum. Meanwhile, the raw iron ore tailings (before iron recovery) with the same proportion of TSC1 were selected to compare the cementitious activity of raw tailings and the residues after magnetizing roasting, denoted by TSC0. The hydration products of them were mostly ettringite, calcium hydroxide and C-S-H gel, characterized by XRD, IR and SEM. It was found that ettringite and C-S-H gel were principally responsible for the strength development of TSC mortars with curing time. The results showed that the kaolinite of the tailings was decomposed completely after magnetizing roasting, which promoted the cementitious property of TSC1. Moreover, the mechanical properties of TSC1 are well comparable with those of 42.5 ordinary Portland cement according to Chinese GB175-2007 standard. PMID:19782471

  20. The Behaviours of Cementitious Materials in Long Term Storage and Disposal of Radioactive Waste. Results of a Coordinated Research Project

    International Nuclear Information System (INIS)

    Radioactive waste with widely varying characteristics is generated from the operation and maintenance of nuclear power plants, nuclear fuel cycle facilities, research laboratories and medical facilities. This waste must be treated and conditioned, as necessary, to provide waste forms acceptable for safe storage and disposal. Many countries use cementitious materials (concrete, mortar, etc.) as a containment matrix for immobilization, as well as for engineered structures of disposal facilities. Radionuclide release is dependent on the physicochemical properties of the waste forms and packages, and on environmental conditions. In the use of cement, the diffusion process and metallic corrosion can induce radionuclide release. The advantage of cementitious materials is the added stability and mechanical support during storage and disposal of waste. Long interim storage is becoming an important issue in countries where it is difficult to implement low level waste and intermediate level waste disposal facilities, and in countries where cement is used in the packaging of waste that is not suitable for shallow land disposal. This coordinated research project (CRP), involving 24 research organizations from 21 Member States, investigated the behaviour and performance of cementitious materials used in an overall waste conditioning system based on the use of cement - including waste packaging (containers), waste immobilization (waste form) and waste backfilling - during long term storage and disposal. It also considered the interactions and interdependencies of these individual elements (containers, waste, form, backfill) to understand the processes that may result in degradation of their physical and chemical properties. The main research outcomes of the CRP are summarized in this report under four topical sections: (i) conventional cementitious systems; (ii) novel cementitious materials and technologies; (iii) testing and waste acceptance criteria; and (iv) modelling long

  1. Cementitious Barriers Partnership Scm Paste Samples Exposed To Aggressive Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Foster, T. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2014-12-01

    The Cementitious Barriers Partnership (CBP) Project is a multi-disciplinary, multi-institutional collaboration supported by the United States Department of Energy (US DOE) Office of Waste Processing. The objective of the CBP project is to develop a set of tools to improve understanding and prediction of the long-term structural, hydraulic, and chemical performance of cementitious barriers used in nuclear applications.

  2. Cementitious barriers partnership transport properties of damaged materials

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2014-11-01

    The Cementitious Barriers Partnership (CBP) Project is a multi-disciplinary, multi-institutional collaboration supported by the United States Department of Energy (US DOE) Office of Waste Processing. The objective of the CBP project is to develop a set of tools to improve understanding and prediction of the long-term structural, hydraulic, and chemical performance of cementitious barriers used in nuclear applications.

  3. Review of durability of cementitious engineered barriers in repository environments

    International Nuclear Information System (INIS)

    This report is concerned with the durability of cementitious engineered barriers in a repository for low and intermediate level nuclear waste. Following the introduction the second section of the review identifies the environmental conditions associated with a deep, hard rock repository for ILW and LLW that are relevant to the durability of cementitious barriers. Section three examines the microstructure and macrostructure of cementitious materials and considers the physical and chemical processes of radionuclide immobilization. Potential repository applications and compositions of cementitious materials are reviewed in Section four. The main analysis of durability is dealt with in Section five. The different types of cementitious barrier are considered separately and their most probable modes of degradation are analysed. Concluding remarks that highlight critical technical matters are given in Section six. (author)

  4. Self-degradable Cementitious Sealing Materials

    Energy Technology Data Exchange (ETDEWEB)

    Sugama, T.; Butcher, T., Lance Brothers, Bour, D.

    2010-10-01

    A self-degradable alkali-activated cementitious material consisting of a sodium silicate activator, slag, Class C fly ash, and sodium carboxymethyl cellulose (CMC) additive was formulated as one dry mix component, and we evaluated its potential in laboratory for use as a temporary sealing material for Enhanced Geothermal System (EGS) wells. The self-degradation of alkali-activated cementitious material (AACM) occurred, when AACM heated at temperatures of {ge}200 C came in contact with water. We interpreted the mechanism of this water-initiated self-degradation as resulting from the in-situ exothermic reactions between the reactants yielded from the dissolution of the non-reacted or partially reacted sodium silicate activator and the thermal degradation of the CMC. The magnitude of self-degradation depended on the CMC content; its effective content in promoting degradation was {ge}0.7%. In contrast, no self-degradation was observed from CMC-modified Class G well cement. For 200 C-autoclaved AACMs without CMC, followed by heating at temperatures up to 300 C, they had a compressive strength ranging from 5982 to 4945 psi, which is {approx}3.5-fold higher than that of the commercial Class G well cement; the initial- and final-setting times of this AACM slurry at 85 C were {approx}60 and {approx}90 min. Two well-formed crystalline hydration phases, 1.1 nm tobermorite and calcium silicate hydrate (I), were responsible for developing this excellent high compressive strength. Although CMC is an attractive, as a degradation-promoting additive, its addition to both the AACM and the Class G well cement altered some properties of original cementitious materials; among those were an extending their setting times, an increasing their porosity, and lowering their compressive strength. Nevertheless, a 0.7% CMC-modified AACM as self-degradable cementitious material displayed the following properties before its breakdown by water; {approx}120 min initial- and {approx}180 min final

  5. Absorbency of Superabsorbent Polymers in Cementitious Environments

    DEFF Research Database (Denmark)

    Esteves, Luis Pedro; Jensen, Ole Mejlhede

    2012-01-01

    Optimal use of superabsorbent polymers (SAP) in cement-based materials relies on knowledge on how SAP absorbency is influenced by different physical and chemical parameters. These parameters include salt concentration in the pore fluid, temperature of the system and SAP particle size. The present...... composition of the exposure liquid is investigated with atomic absorption spectroscopy. The paper provides the reader with knowledge about the absorption capacity of SAP in a cementitious environment, and how the absorption process may influence the cement pore fluid....

  6. Chloride ingress in cement paste and mortar

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben; Coats, Alison M.; Glasser, Fred P.

    1999-01-01

    In this paper chloride ingress in cement paste and mortar is followed by electron probe microanalysis. The influence of several paste and exposure parameters on chloride ingress are examined (e.g., water-cement ratio, silica fume addition, exposure time, and temperature), The measurements are...

  7. Characteristics of mortars from ancient bridges

    Czech Academy of Sciences Publication Activity Database

    Frankeová, Dita; Slížková, Zuzana; Drdácký, Miloš

    Vol. 7. Dordrecht : Springer, 2012 - (Válek, J.; Hughes, J.; Groot, J.), s. 165-174 ISBN 978-94-007-4634-3 R&D Projects: GA ČR(CZ) GA103/09/2067; GA MŠk(CZ) LA09008 Institutional support: RVO:68378297 Keywords : mortars * ancient bridges * analytical methods Subject RIV: AL - Art, Architecture, Cultural Heritage

  8. Analysis of Graphite-Reinforced Cementitious Composites

    Science.gov (United States)

    Vaughan, R. E.

    2002-01-01

    Strategically embedding graphite meshes in a compliant cementitious matrix produces a composite material with relatively high tension and compressive properties as compared to steel-reinforced structures fabricated from a standard concrete mix. Although these composite systems are somewhat similar, the methods used to analyze steel-reinforced composites often fail to characterize the behavior of their more advanced graphite-reinforced counterparts. This Technical Memorandum describes some of the analytical methods being developed to determine the deflections and stresses in graphite-reinforced cementitious composites. It is initially demonstrated that the standard transform section method fails to provide accurate results when the elastic moduli ratio exceeds 20. An alternate approach is formulated by using the rule of mixtures to determine a set of effective material properties for the composite. Tensile tests are conducted on composite samples to verify this approach. When the effective material properties are used to characterize the deflections of composite beams subjected to pure bending, an excellent agreement is obtained. Laminated composite plate theory is investigated as a means for analyzing even more complex composites, consisting of multiple graphite layers oriented in different directions. In this case, composite beams are analyzed using the laminated composite plate theory with material properties established from tensile tests. Then, finite element modeling is used to verify the results. Considering the complexity of the samples, a very good agreement is obtained.

  9. The Cementitious Barriers Partnership (CBP) Software Toolbox Capabilities In Assessing The Degradation Of Cementitious Barriers

    International Nuclear Information System (INIS)

    The Cementitious Barriers Partnership (CBP) Project is a multi-disciplinary, multi-institutional collaboration supported by the U.S. Department of Energy (US DOE) Office of Tank Waste and Nuclear Materials Management. The CBP program has developed a set of integrated tools (based on state-of-the-art models and leaching test methods) that help improve understanding and predictions of the long-term structural, hydraulic and chemical performance of cementitious barriers used in nuclear applications. Tools selected for and developed under this program have been used to evaluate and predict the behavior of cementitious barriers used in near-surface engineered waste disposal systems for periods of performance up to 100 years and longer for operating facilities and longer than 1000 years for waste disposal. The CBP Software Toolbox has produced tangible benefits to the DOE Performance Assessment (PA) community. A review of prior DOE PAs has provided a list of potential opportunities for improving cementitious barrier performance predictions through the use of the CBP software tools. These opportunities include: 1) impact of atmospheric exposure to concrete and grout before closure, such as accelerated slag and Tc-99 oxidation, 2) prediction of changes in Kd/mobility as a function of time that result from changing pH and redox conditions, 3) concrete degradation from rebar corrosion due to carbonation, 4) early age cracking from drying and/or thermal shrinkage and 5) degradation due to sulfate attack. The CBP has already had opportunity to provide near-term, tangible support to ongoing DOE-EM PAs such as the Savannah River Saltstone Disposal Facility (SDF) by providing a sulfate attack analysis that predicts the extent and damage that sulfate ingress will have on the concrete vaults over extended time (i.e., > 1000 years). This analysis is one of the many technical opportunities in cementitious barrier performance that can be addressed by the DOE-EM sponsored CBP software

  10. The Cementitious Barriers Partnership (CBP) Software Toolbox Capabilities in Assessing the Degradation of Cementitious Barriers - 13487

    International Nuclear Information System (INIS)

    The Cementitious Barriers Partnership (CBP) Project is a multi-disciplinary, multi-institutional collaboration supported by the U.S. Department of Energy (US DOE) Office of Tank Waste and Nuclear Materials Management. The CBP program has developed a set of integrated tools (based on state-of-the-art models and leaching test methods) that help improve understanding and predictions of the long-term structural, hydraulic and chemical performance of cementitious barriers used in nuclear applications. Tools selected for and developed under this program have been used to evaluate and predict the behavior of cementitious barriers used in near-surface engineered waste disposal systems for periods of performance up to 100 years and longer for operating facilities and longer than 1000 years for waste disposal. The CBP Software Toolbox has produced tangible benefits to the DOE Performance Assessment (PA) community. A review of prior DOE PAs has provided a list of potential opportunities for improving cementitious barrier performance predictions through the use of the CBP software tools. These opportunities include: 1) impact of atmospheric exposure to concrete and grout before closure, such as accelerated slag and Tc-99 oxidation, 2) prediction of changes in Kd/mobility as a function of time that result from changing pH and redox conditions, 3) concrete degradation from rebar corrosion due to carbonation, 4) early age cracking from drying and/or thermal shrinkage and 5) degradation due to sulfate attack. The CBP has already had opportunity to provide near-term, tangible support to ongoing DOE-EM PAs such as the Savannah River Saltstone Disposal Facility (SDF) by providing a sulfate attack analysis that predicts the extent and damage that sulfate ingress will have on the concrete vaults over extended time (i.e., > 1000 years). This analysis is one of the many technical opportunities in cementitious barrier performance that can be addressed by the DOE-EM sponsored CBP software

  11. The Cementitious Barriers Partnership (CBP) Software Toolbox Capabilities In Assessing The Degradation Of Cementitious Barriers

    Energy Technology Data Exchange (ETDEWEB)

    Flach, G. P. [Savannah River Site (SRS), Aiken, SC (United States); Burns, H. H. [Savannah River Site (SRS), Aiken, SC (United States); Langton, C. [Savannah River Site (SRS), Aiken, SC (United States); Smith, F. G. III [Savannah River Site (SRS), Aiken, SC (United States); Brown, K. G. [Vanderbilt University, Nashville, TN (United States); Kosson, D. S. [Vanderbilt University, Nashville, TN (United States); Garrabrants, A. C. [Vanderbilt University, Nashville, TN (United States); Sarkar, S. [Vanderbilt University, Nashville, TN (United States); van der Sloot, H. [Hans van der Sloot Consultancy (The Netherlands); Meeussen, J. C.L. [Nuclear Research and Consultancy Group, Petten (The Netherlands); Samson, E. [SIMCO Technologies Inc. , 1400, boul. du Parc - Technologique , Suite 203, Quebec (Canada); Mallick, P. [United States Department of Energy, 1000 Independence Ave. SW , Washington, DC (United States); Suttora, L. [United States Department of Energy, 1000 Independence Ave. SW , Washington, DC (United States); Esh, D. W. [U .S. Nuclear Regulatory Commission , Washington, DC (United States); Fuhrmann, M. J. [U .S. Nuclear Regulatory Commission , Washington, DC (United States); Philip, J. [U .S. Nuclear Regulatory Commission , Washington, DC (United States)

    2013-01-11

    The Cementitious Barriers Partnership (CBP) Project is a multi-disciplinary, multi-institutional collaboration supported by the U.S. Department of Energy (US DOE) Office of Tank Waste and Nuclear Materials Management. The CBP program has developed a set of integrated tools (based on state-of-the-art models and leaching test methods) that help improve understanding and predictions of the long-term structural, hydraulic and chemical performance of cementitious barriers used in nuclear applications. Tools selected for and developed under this program have been used to evaluate and predict the behavior of cementitious barriers used in near-surface engineered waste disposal systems for periods of performance up to 100 years and longer for operating facilities and longer than 1000 years for waste disposal. The CBP Software Toolbox has produced tangible benefits to the DOE Performance Assessment (PA) community. A review of prior DOE PAs has provided a list of potential opportunities for improving cementitious barrier performance predictions through the use of the CBP software tools. These opportunities include: 1) impact of atmospheric exposure to concrete and grout before closure, such as accelerated slag and Tc-99 oxidation, 2) prediction of changes in Kd/mobility as a function of time that result from changing pH and redox conditions, 3) concrete degradation from rebar corrosion due to carbonation, 4) early age cracking from drying and/or thermal shrinkage and 5) degradation due to sulfate attack. The CBP has already had opportunity to provide near-term, tangible support to ongoing DOE-EM PAs such as the Savannah River Saltstone Disposal Facility (SDF) by providing a sulfate attack analysis that predicts the extent and damage that sulfate ingress will have on the concrete vaults over extended time (i.e., > 1000 years). This analysis is one of the many technical opportunities in cementitious barrier performance that can be addressed by the DOE-EM sponsored CBP software

  12. The Cementitious Barriers Partnership (CBP) Software Toolbox Capabilities in Assessing the Degradation of Cementitious Barriers - 13487

    Energy Technology Data Exchange (ETDEWEB)

    Flach, G.P.; Burns, H.H.; Langton, C.; Smith, F.G. III [Savannah River National Laboratory, Savannah River Site, Aiken SC 29808 (United States); Brown, K.G.; Kosson, D.S.; Garrabrants, A.C.; Sarkar, S. [Vanderbilt University, Nashville, TN (United States); Van der Sloot, H. [Hans Van der Sloot Consultancy (Netherlands); Meeussen, J.C.L. [Nuclear Research and Consultancy Group, Petten (Netherlands); Samson, E. [SIMCO Technologies Inc., 1400, boul. du Parc-Technologique, Suite 203, Quebec (Canada); Mallick, P.; Suttora, L. [United States Department of Energy, 1000 Independence Ave. SW, Washington, DC (United States); Esh, D.W.; Fuhrmann, M.J.; Philip, J. [U.S. Nuclear Regulatory Commission, Washington, DC (United States)

    2013-07-01

    The Cementitious Barriers Partnership (CBP) Project is a multi-disciplinary, multi-institutional collaboration supported by the U.S. Department of Energy (US DOE) Office of Tank Waste and Nuclear Materials Management. The CBP program has developed a set of integrated tools (based on state-of-the-art models and leaching test methods) that help improve understanding and predictions of the long-term structural, hydraulic and chemical performance of cementitious barriers used in nuclear applications. Tools selected for and developed under this program have been used to evaluate and predict the behavior of cementitious barriers used in near-surface engineered waste disposal systems for periods of performance up to 100 years and longer for operating facilities and longer than 1000 years for waste disposal. The CBP Software Toolbox has produced tangible benefits to the DOE Performance Assessment (PA) community. A review of prior DOE PAs has provided a list of potential opportunities for improving cementitious barrier performance predictions through the use of the CBP software tools. These opportunities include: 1) impact of atmospheric exposure to concrete and grout before closure, such as accelerated slag and Tc-99 oxidation, 2) prediction of changes in K{sub d}/mobility as a function of time that result from changing pH and redox conditions, 3) concrete degradation from rebar corrosion due to carbonation, 4) early age cracking from drying and/or thermal shrinkage and 5) degradation due to sulfate attack. The CBP has already had opportunity to provide near-term, tangible support to ongoing DOE-EM PAs such as the Savannah River Saltstone Disposal Facility (SDF) by providing a sulfate attack analysis that predicts the extent and damage that sulfate ingress will have on the concrete vaults over extended time (i.e., > 1000 years). This analysis is one of the many technical opportunities in cementitious barrier performance that can be addressed by the DOE-EM sponsored CBP

  13. Damage development, phase changes, transport properties, and freeze-thaw performance of cementitious materials exposed to chloride based salts

    Science.gov (United States)

    Farnam, Yaghoob

    Recently, there has been a dramatic increase in premature deterioration in concrete pavements and flat works that are exposed to chloride based salts. Chloride based salts can cause damage and deterioration in concrete due to the combination of factors which include: increased saturation, ice formation, salt crystallization, osmotic pressure, corrosion in steel reinforcement, and/or deleterious chemical reactions. This thesis discusses how chloride based salts interact with cementitious materials to (1) develop damage in concrete, (2) create new chemical phases in concrete, (3) alter transport properties of concrete, and (4) change the concrete freeze-thaw performance. A longitudinal guarded comparative calorimeter (LGCC) was developed to simultaneously measure heat flow, damage development, and phase changes in mortar samples exposed to sodium chloride (NaCl), calcium chloride (CaCl 2), and magnesium chloride (MgCl2) under thermal cycling. Acoustic emission and electrical resistivity measurements were used in conjunction with the LGCC to assess damage development and electrical response of mortar samples during cooling and heating. A low-temperature differential scanning calorimetry (LT-DSC) was used to evaluate the chemical interaction that occurs between the constituents of cementitious materials (i.e., pore solution, calcium hydroxide, and hydrated cement paste) and salts. Salts were observed to alter the classical phase diagram for a salt-water system which has been conventionally used to interpret the freeze-thaw behavior in concrete. An additional chemical phase change was observed for a concrete-salt-water system resulting in severe damage in cementitious materials. In a cementitious system exposed to NaCl, the chemical phase change occurs at a temperature range between -6 °C and 8 °C due to the presence of calcium sulfoaluminate phases in concrete. As a result, concrete exposed to NaCl can experience additional freeze-thaw cycles due to the chemical

  14. Development of leachate test for delayed ettringite formation potential in cementitious materials

    Science.gov (United States)

    France-Mensah, Jojo

    Delayed Ettringite Formation (DEF) has been known to be the cause of expansion and cracking at latter ages in concrete that has been heat cured at temperatures around 70 degree Celsius or above. Currently, the only method available for measuring DEF-related physical expansion in concrete can sometimes take over a year to yield relevant results. A leachate method was proposed as a means of taking advantage of the release and solubility of the adsorbed ions (e.g., calcium, sulfates and aluminates) and alkali ions (e.g., sodium and potassium) in the pore solution after heat curing of the cement paste matrix. These ions, known to contribute to DEF, were leached out of concrete into the leaching solution. The results of the leachate test were correlated to physical expansion data of similar samples from an earlier study. The aim of this research is to apply this knowledge to develop an accelerated leachate test method for identifying the potential for DEF in cementitious materials in a shorter time than the existing method. The objectives of this research are: (1) to identify the ion(s) through leaching that is/are the controlling factors in predicting the rate of expansion and overall expansion of mortar; (2) to identify the ion(s) that is/are responsible for the lag time or age of deleterious expansion through DEF; and (3) to investigate the effect of heat curing on the overall, rate of, and age (time) of expansion.

  15. Microstructural changes in a cementitious membrane due to the application of a DC electric field.

    Science.gov (United States)

    Covelo, Alba; Diaz, Belen; Freire, Lorena; Novoa, X Ramon; Perez, M Consuelo

    2008-07-01

    The use of electromigration techniques to accelerate chloride ions motion is commonly employed to characterise the permeability of cementitious samples to chlorides, a relevant parameter in reinforced concrete corrosion. This paper is devoted to the study of microstructure's changes occurring in mortar samples when submitted to natural diffusion and migration experiments. The application of an electric field reduces testing time in about one order of magnitude with respect to natural diffusion experiments. Nevertheless, the final sample's microstructure differs in both tests. Impedance Spectroscopy is employed for real time monitoring of microstructural changes. During migration experiments the global impedance undergoes important increase in shorter period of time compared to natural diffusion tests. So, the forced motion of ions through the concrete membrane induces significant variations in the porous structure, as confirmed by Mercury Intrusion Porosimetry. After migration experiments, an important increase in the capillary pore size (10-100 nm) was detected. Conversely, no relevant variations are found after natural diffusion tests. Results presented in this work cast doubt on the significance of diffusion coefficient values obtained under accelerated conditions. PMID:18569312

  16. Cementitious binders from activated stainless steel refining slag and the effect of alkali solutions.

    Science.gov (United States)

    Salman, Muhammad; Cizer, Özlem; Pontikes, Yiannis; Snellings, Ruben; Vandewalle, Lucie; Blanpain, Bart; Van Balen, Koen

    2015-04-01

    With an aim of producing high value cementitious binder, stainless steel refining slag containing a high amount of CaO in γ-dicalcium silicate form was activated with NaOH and Na-silicate as well as KOH and K-silicate solutions, followed by steam curing at 80 °C. Higher levels of alkali-silicate in the activating solution resulted in higher cumulative heat suggesting accelerated reaction kinetics. With respect to compressive strength, higher levels of alkali silicate resulted in higher strength and the mortars with Na activator were found to have higher early strength than the ones with K activator. The long term strength was found to be similar, regardless of the alkali metal. Thermogravimetric, QXRD and FTIR analyses showed an increase in the amount of reaction products (C-S-H type) over time, further confirming the reactivity of the crystalline slag. Batch leaching results showed lower leaching of heavy metals and metalloids with K activator compared to the Na activator. These results demonstrate that the alkali type and the ratio of hydroxide to silicates have a significant impact on the hydration and mechanical strength development of the stainless steel slag. The above findings can aid in the recycling and valorization of these type of slags which otherwise end up landfilled. PMID:25577317

  17. Chemical path of ettringite formation in heat-cured mortar and its relationship to expansion

    Science.gov (United States)

    Shimada, Yukie

    Delayed ettringite formation (DEF) refers to a deterioration process of cementitious materials that have been exposed to high temperatures and subsequent moist conditions, often resulting in damaging expansion. The occurrence of DEF-related damage may lead to severe economic consequences. While concerns of related industries continue to raise the need for reliable and practical test methods for DEF assessment, the mechanism(s) involved in DEF remains controversial. In order to provide a better understanding of the DEF phenomenon, the present study investigated mortar systems made with various mixing and curing parameters for detailed changes in pore solution chemistry and solid phase development, while corresponding changes in physical properties were also closely monitored. This approach enabled the development of a correlation between the chemical and physical changes and provided the opportunity for a holistic analysis. The present study revealed that there exist relationships between the physical properties and expansive behavior. The normal aging process of the cementitious systems involves dissolution of ettringite crystals finely distributed within the hardened cement paste and subsequent recrystallization as innocuous crystals in the largest accessible spaces. This process, known as Ostwald ripening, facilitates relaxation of any expansive pressure developed within the paste. The rate of Ostwald ripening is rather slow in a well-compacted, dense microstructure containing few flaws. Thus, an increase in mechanical strength accompanied by a reduction in diffusion rate by altering the mortar parameters increases the risk of DEF-related expansion and vice versa. Introduction of the Ostwald ripening process as a stress relief mechanism to the previously proposed paste expansion hypothesis provides a comprehensive description of the observed expansive behavior. Chemical analyses provided semi-quantitative information on the stability of ettringite during high

  18. Nano-modified cement composites and its applicability as concrete repair material

    Science.gov (United States)

    Manzur, Tanvir

    optimum mix proportion to produce CNT reinforced cement composites. In this study, an extensive parametric study has been conducted using different types of treated and untreated multi walled nanotubes (MWNT) as reinforcement of cementitious composites having different mix proportions. It is found that mixing of nanotubes within cement matrix is the key to develop composites having desirable properties. A mixing technique has been proposed to address the issues related to dispersion of nanotubes within cement matrix. Polycarboxylate based super plasticizer has been proposed to use as surfactant. It is evident that there exists an optimum concentration of MWNT and mix proportion to achieve proper reinforcement behavior and strength properties. The affect of size of MWNT on strengths (both compressive and flexure) of composites has also been investigated. Based on the parametric study and statistical analysis, a tentative optimum mix proportion has been proposed. Composites made by the proposed mixing technique and design mix obtained 26, 27 and 16% higher compressive strength as compared to control samples at the age of 3, 7 and 28 day, respectively. Flexural strengths of those composites at 3, 7 and 28 day were about 24, 24.5 and 20% higher than that of control samples, respectively. It has also been suggested that application of MWNT reinforced cement mortar as concrete repair material has excellent potential since composites exhibited desirable behavior in setting time, bleeding and slant shear.

  19. Mineralogical, textural and physical-mechanical study of hydraulic lime mortars cured under different moisture conditions

    Directory of Open Access Journals (Sweden)

    Arizzi, A.

    2015-06-01

    Full Text Available This work focuses on the chemical-mineralogical, textural and physical-mechanical properties of hydraulic lime mortars made with siliceous and calcareous aggregate. Mortars were cured at 60% and 90% of relative humidity, so as to assess the variability of mortar petrophysical properties in the hardened state due to the moisture conditions. The final aim was to determine the most adequate moisture conditions to be maintained during application and hardening of hydraulic mortars intended for repair interventions. We found out that using a calcareous aggregate and curing mortar at 90% of relative humidity give place to better textural and mechanical properties. However, these characteristics mostly depend on the maximum size of the aggregate grains, which should be smaller than 6 mm, in order to avoid the occurrence of mechanical discontinuities in the mortar.En este trabajo se han estudiado las propiedades químico-mineralógicas, texturales y físico-mecánicas de morteros de cal hidráulica elaborados con áridos silíceo y calcítico. Estos morteros se han curado al 60% y 90% de humedad relativa, con el fin de evaluar las eventuales diferencias en las propiedades petrofísicas de los morteros una vez endurecidos y así establecer cuál de los dos ambientes es recomendable durante la aplicación y fraguado de morteros de cal hidráulica destinados a obras de restauración. Se ha encontrado que el uso de un árido de composición calcítica y el curado al 90% de humedad relativa dan lugar a morteros hidráulicos con mejores características texturales y propiedades mecánicas. De todas formas, estas características dependen principalmente del tamaño máximo del árido empleado, que debería ser inferior a 6 mm para evitar discontinuidades mecánicas en el mortero.

  20. Improved cement mortars by addition of carbonated fly ash from solid waste incinerators

    Directory of Open Access Journals (Sweden)

    López-Zaldívar, O.

    2015-09-01

    Full Text Available This article presents the results of a research developing high performance cement mortars with the addition of municipal solid waste incineration fly ash (MSWIFA stabilized as insoluble carbonates. The encapsulation of hazardous wastes in mortar matrixes has also been achieved. The ashes present high concentrations of chlorides, Zn and Pb. A stabilization process with NaHCO3 has been developed reducing 99% the content of chlorides. Developed mortars replace 10% per weight of the aggregates by treated MSWIFA. Physical/mechanical properties of these mortars have been studied. Presence of Zn, Pb, Cu and Cd has been also analyzed confirming that leaching of these heavy metal ions is mitigated. Conclusions prove better behavior of CAC and CSA mortars than those of CEM-I and CEM-II cement. Results are remarkable for the CAC mortars, improving reference strengths in more than 25%, which make them a fast-curing product suitable for the repair of structures or industrial pavements.Este artículo presenta los resultados del desarrollo de morteros mejorados con la incorporación de cenizas volantes de residuos sólidos urbanos inertizadas en forma de carbonatos. Además se consigue la encapsulación de un residuo peligroso. Las cenizas presentan una alta concentración de cloruros, Zn y Pb. Se ha desarrollado un proceso de estabilización con NaHCO3 reduciendo en un 99% el contenido de cloruros. Los morteros reemplazan un 10% en peso del árido por cenizas tratadas. Se han analizado sus propiedades físico/mecánicas y la presencia de Zn, Pb, Cu y Cd. Se demuestra un mejor comportamiento de los morteros de CAC y CSA que los de CEM-I y CEM-II y se mitiga el lixiviado de metales pesados. Los resultados son significativos en los morteros CAC al mejorar las resistencias de los de referencia en un 25%. Los morteros desarrollados son de curado rápido adecuados para la reparación de estructuras o soleras industriales.

  1. Development of low weight self-levelling mortars

    International Nuclear Information System (INIS)

    This work shows the development of self levelling mortars, using micro bubbles based on aluminium silicate with a density of 0.25 g/cm3. Mortars formulations are composed by 8 different components in order to achieve properties balance between fresh and solid state. The mean objective is development light weight mortars with high fluidity and compression strength using micro bubbles and some additives. Formulations were designed employing Taguchi DOE of 8 variables and 3 states. Result analysis according to Taguchi method lets indentify the preponderant effect of each variable on the cited properties. Several formulations reached fluidity higher than 250%, with compression strength around 100 kg/cm2 and a low volumetric weigh. Obtained volumetric weights are 20% less than commercial self levelling mortars weight. Finally some relations are presented such: as relation water/cement with fluidity, and micro bubble content versus mortars volumetric weight, and finally compression strength versus the volumetric weight of mortars

  2. Compressive strength of brick masonry made with weak mortars

    DEFF Research Database (Denmark)

    Pedersen, Erik Steen; Hansen, Klavs Feilberg

    2013-01-01

    strength of masonry depends only on the strength of the bricks. A compression failure in masonry made with weak mortars occurs as a tension failure in the bricks, as they seek to prevent the mortar from being pressed out of the joints. The expression is derived by assuming hydrostatic pressure in the...... mortar joints, which is the most unfavourable stress distribution with respect to tensile stresses in bricks. The expression is compared with the results of compression tests of masonry made with weak mortars. It can take into account bricks with arbitrary dimensions as well as perforated bricks. For a...... stronger mortar (fm≈6 N/mm2) compression tests of masonry with perforated bricks show that the EC6 expression is not always safe for Danish masonry. This is probably because the tensile strength of the bricks also has an effect on the compressive strength of masonry when the mortar is stronger than weak...

  3. Low Carbon Footprint Mortar from Pozzolanic Waste Material

    OpenAIRE

    Taha Mehmannavaz; Salihuddin Radin Sumadi; Muhammad Aamer Rafique Bhutta; Mostafa Samadi; Seyed Mahdi Sajjadi

    2014-01-01

    Nowadays, Portland cement clinker leads to emission of CO2 into the atmosphere and therefore causes greenhouse effect. Incorporating of Palm Oil Fuel Ash (POFA) and Pulverized Fuel Ash (PFA) as partial cement replacement materials into mix of low carbon mortar decreases the amount of cement use and reduces high dependence on cements compared to ordinary mortar. The result of this research supported use of the new concept in preparing low carbon mortar for industrial constructions. Strength of...

  4. Role of different superplasticizers on hydrated lime pastes and mortars

    OpenAIRE

    Alvarez, J. I.; Fernandez, J M; Sirera, R. (Rafael); Perez-Nicolas, M. (María); Navarro-Blasco, I. (Íñigo); Duran, A

    2015-01-01

    The behaviour of different superplasticizers admixtures was assessed for hydrated lime pastes and mortars. Sometimes, air lime pastes and mortars were modified with two supplementary cementing materials (SCMs), namely nanosilica (NS) and metakaolin (MK). Two different polycarboxylate ethers, a lignosulfonate and a naphthalene condensed sulfonate superplasticizer were added to lime pastes and mortars and their effects on fresh-state properties as well as on the mechanical strengths were evalua...

  5. Comparative evaluation of aerial lime mortars for architectural conservation

    OpenAIRE

    Faria, Paulina; Henriques, Fernando M.A.; Rato, Vasco

    2008-01-01

    Journal of Cultural Heritage 9 (2008) 338-346 International bibliography on conservation usually refers that mortars made with lime putty with long extinction periods behave better than others made with the current dry hydrated limes. In order to evaluate this assess, an experimental study of lime mortars was carried out, using dry hydrated lime and two lime putties. It becomes clear that the use of lime putties with long extinction periods in mortars allow better performances, pa...

  6. Effect of kaolin treatment temperature on mortar chloride permeability

    OpenAIRE

    Puertas, F.; Mejía de Gutiérrez, R.; J. Torres

    2007-01-01

    The present paper discusses the results of chloride resistance tests conducted on ordinary Portland cement (OPC) mortars containing a Colombian kaolin pre-treated at temperatures of from 600 to 800 ºC. The resulting metakaolin (MK) was added to OPC mortar mixes in proportions of 10 and 20% by cement weight. The mortars were compared for physical and chemical properties, including capillary absorption, chloride permeability and pore microstructure as assessed by mercury porosimetry....

  7. Influence of Pore Structure on Compressive Strength of Cement Mortar

    OpenAIRE

    Haitao Zhao; Qi Xiao; Donghui Huang; Shiping Zhang

    2014-01-01

    This paper describes an experimental investigation into the pore structure of cement mortar using mercury porosimeter. Ordinary Portland cement, manufactured sand, and natural sand were used. The porosity of the manufactured sand mortar is higher than that of natural sand at the same mix proportion; on the contrary, the probable pore size and threshold radius of manufactured sand mortar are finer. Besides, the probable pore size and threshold radius increased with increasing water to cement r...

  8. Alkaline cement mortars. Chemical resistance to sulfate and seawater attack

    OpenAIRE

    Puertas, F.; Gutiérrez, R.; Fernández-Jiménez, A.; Delvasto, S.; Maldonado, J.

    2002-01-01

    The durability and chemical resistance of alkali activated slag and fly ash/slag mortars in contact with sulfates and seawater media have been studied. Two methods were used in the evaluation of such durability: Kock-Steinegger and ASTM C1012. A mineralogical and a microstructural characterization of mortars were done at different ages of their conservation in aggressive media through XRD, SEM/ EDX and mercury porosimetry. Results showed a high durability of activated cement mortars in s...

  9. Flexural reinforcement of concrete with textile reinforced mortar TRM

    OpenAIRE

    Gil Espert, Lluís; Escrig Pérez, Christian; Bernat Masó, Ernest

    2013-01-01

    This work presents a method of strengthening concrete structures based on textiles of high strength and mortars. The combination of textiles and mortars produces a new composite material of cementitic matrix. This material can be used for the reinforcement of concrete beams under bending loads. We tested several combinations of fibers: glass, PBO, steel and carbon fibers with mortar and we used them to reinforce precast concrete beams. All the specimens were tested with a four-point load test...

  10. Effect of gypsum content on sulfoaluminate mortars stability

    OpenAIRE

    DESBOIS, Tiffany; Le Roy, Robert; PAVOINE, Alexandre; PLATRET, Gérard; FERAILLE-FRESNET, Adélaïde; ALAOUI, Amina

    2010-01-01

    Calcium sulfoaluminate clinker is one of the most promising cements that would lower the greenhouse gas effect accompanying cement production. This article examines the effect of gypsum content on the dimensional stability of sulfoaluminate mortars. Mechanical properties as chemical evolution are studied. Our results show that the mortar with the greatest gypsum content expands without a decrease of its mechanical properties when it is cured in water. Two hypotheses about the mortars hydratio...

  11. Durability of Lightweight Concrete and Mortar Exposed under Some Environment

    OpenAIRE

    Hiroshi, SAKURAI; Koichi, AYUTA; Noboru, SAEKI; Yoshio, Fujita; Seiji, Kaneko; Mikito, IKEDA

    1991-01-01

    In this experiment, identically composed specimens of lightweight concrete and of a mortar material were exposed to a cold (coastal) environment (Monbetsu), warm sea environment (Izu) and used in the roof of a building in a warm-climate city (Yokohama) for 3years. The physical and chemical properties of the lightweight concrete specimens and those of the mortar specimens were examined. The results are as follows : (1) The lightweight concrete specimen contained more salt than the same mortar ...

  12. Estimating compressive strength of concrete by mortar testing

    OpenAIRE

    Camões, Aires; Aguiar, J. L. Barroso de; Jalali, Said

    2005-01-01

    Concrete mix design laboratory tests which time consuming and entails considerable effort. This study presents a method of reducing mix design testing costs by testing mortar instead of concrete specimens. The experimental programme consisted of defining mortar mixes equivalent to concrete mixes, moulding specimens of both mortar and concrete mixes studied and finally evaluating the compressive strength of specimens cured at different curing time. Results obtained indicate that a goo...

  13. Rendering mortars with incorporation of ceramic aggregates

    OpenAIRE

    Mª Rosário Veiga; João Silva; Jorge Brito

    2008-01-01

    In this paper the experimental evaluation of the water-related performance of rendering mortars with incorporation of recycled products is presented, based on three different research vectors: addition of fine recycled aggregates; reduction of the cement content (with simultaneous addition of fines); and replacement of sand with recycled material, with the same overall grading curve. The material presented here as recyclable is brick waste from the ceramics and construction industries.

  14. Domain decomposition methods for mortar finite elements

    Energy Technology Data Exchange (ETDEWEB)

    Widlund, O.

    1996-12-31

    In the last few years, domain decomposition methods, previously developed and tested for standard finite element methods and elliptic problems, have been extended and modified to work for mortar and other nonconforming finite element methods. A survey will be given of work carried out jointly with Yves Achdou, Mario Casarin, Maksymilian Dryja and Yvon Maday. Results on the p- and h-p-version finite elements will also be discussed.

  15. Shrinkage Reducing Measures for Engineering Cementitious Composites

    Institute of Scientific and Technical Information of China (English)

    YANG Yingzi; YAO Yan; GAO Xiaojian; DENG Hongwei; YU Pengzhan

    2008-01-01

    Inhibition measurement of shrinkage of engineering cementitious composites(ECC) was investigated due to typical ECC with higher free drying shrinkage.The effects of expanded admixture (EA),shrinkage reducing admixture (SRA),coarse sand+stone powder (CS+SP)and superabsorbent polymer (SAP) on drying shrinkage and mechanical properties were studied.The experimental results show that ECC incorporating EA,SRA and coarse sand can retain around 60% of the typical ECC's free drying shrinkage.Superabsorbent polymerl(SAP) can delay the development of free drying shrinkage of ECC at different ages,and the effect of SAP is not distinct like the actions of EA,superabsorbent polymer(SRA) and coarse sand.Significantly,SAP may act as artificial flaw to form a more homogeneous defect system that increases the potential of saturated multiple cracking,hence the ductility of ECC will be improved greatly.

  16. Architecture for gas transport through cementitious materials

    Science.gov (United States)

    Vu, Thai Hoa; Frizon, Fabien; Lorente, Sylvie

    2009-05-01

    This paper documents the transport of gaseous species through porous media, with application to cementitious materials. An artificial pore network was created based on mercury intrusion porometry results obtained with samples of cement paste. The flow architecture model consists of parallel channels made of assemblies of truncated cones. Gas diffusion is described as a function of the saturation degree of the material. The model accounts for the effects of the liquid curtains, and the impact of tortuosity on gas diffusion. The results show that constructing an artificial architecture based on Hg porometry allows us to describe with a good accuracy the material porous network. The liquid curtains operate as an obstacle to H2 diffusion. They are determined as a function of the water saturation level and the pore channels geometry. Furthermore, the role of tortuosity as an indicator of gas diffusion accessibility is captured. The sudden drop in the effective diffusion coefficient around a saturation degree of 70% is predicted accurately.

  17. The synthesis of cementitious compounds in molten salts

    OpenAIRE

    Sheikh, R. A.

    2016-01-01

    This thesis describes an investigation into the synthesis of cementitious compounds in molten salts. These compounds are produced in energy-intensive industries (EIIs), such as the cement process, and are responsible for emitting significant quantities of carbon dioxide (CO2) emissions. Molten salt synthesis (MSS) involves dissolving compounds in a molten salt and reacting in solution. If the MSS of cementitious compounds can occur at lower temperatures than EIIs, this could lead to fewer qua...

  18. High-Performance Grouting Mortar Based on Mineral Admixtures

    Directory of Open Access Journals (Sweden)

    Cong Ma

    2015-01-01

    Full Text Available A study on high-performance grouting mortar is reported. The common mortar was modified by mineral admixtures such as gypsum, bauxite, and alunite. The effects of mineral admixtures on the fluidity, setting time, expansion, strength, and other properties of mortar were evaluated experimentally. The microstructure of the modified mortar was characterized by X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry. Moreover, the expansive performance and strength of the grouting mortar were verified by anchor pullout test. The results show that the best conditions for gypsum-bauxite grouting mortar are as follows: a water-to-binder ratio of 0.3, a mineral admixture content of ~15%, and a molar ratio K of 2. The ultimate bearing capacity of the gypsum-bauxite grouting mortar anchor increased by 39.6% compared to the common mortar anchor. The gypsum-bauxite grouting mortar has good fluidity, quick-setting, microexpansion, early strength, and high strength performances.

  19. Challenges and Benefits of Utilizing Carbon Nanofilaments in Cementitious Materials

    Directory of Open Access Journals (Sweden)

    Ardavan Yazdanbakhsh

    2012-01-01

    Full Text Available Carbon nanofibers/tubes (CNF/Ts are very strong and stiff and as a result, are expected to be capable of enhancing the mechanical properties of cementitious materials significantly. Yet there are practical issues concerning the utilization of CNF/Ts in cementitious materials. This study summarizes some of the past efforts made by different investigators for utilizing carbon nanofilaments in cementitious materials and also reports recent experimental research performed by the authors on the mechanical properties of CNF-reinforced hardened cement paste. The major difficulties concerning the utilization of CNF/Ts in cementitious materials are introduced and discussed. Most of these difficulties are related to the poor dispersibility of CNF/Ts. However, the findings from the research presented in this work indicate that, despite these difficulties, carbon nanofilaments can significantly improve the mechanical properties of cementitious materials. The results show that CNFs, even when poorly dispersed within the cementitious matrix, can remarkably increase the flexural strength and cracking resistance of concrete subjected to drying conditions.

  20. Entombment Using Cementitious Materials: Design Considerations and International Experience

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, Roger Ray

    2002-08-01

    Cementitious materials have physical and chemical properties that are well suited for the requirements of radioactive waste management. Namely, the materials have low permeability and durability that is consistent with the time frame required for short-lived radionuclides to decay. Furthermore, cementitious materials can provide a long-term chemical environment that substantially reduces the mobility of some long-lived radionuclides of concern for decommissioning (e.g., C-14, Ni-63, Ni-59). Because of these properties, cementitious materials are common in low-level radioactive waste disposal facilities throughout the world and are an attractive option for entombment of nuclear facilities. This paper describes design considerations for cementitious barriers in the context of performance over time frames of a few hundreds of years (directed toward short-lived radionuclides) and time frames of thousands of years (directed towards longer-lived radionuclides). The emphasis is on providing an overview of concepts for entombment that take advantage of the properties of cementitious materials and experience from the design of low-level radioactive waste disposal facilities. A few examples of the previous use of cementitious materials for entombment of decommissioned nuclear facilities and proposals for the use in future decommissioning of nuclear reactors in a few countries are also included to provide global perspective.

  1. Entombment Using Cementitious Materials: Design Considerations and International Experience

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, R.R.

    2002-05-15

    Cementitious materials have physical and chemical properties that are well suited for the requirements of radioactive waste management. Namely, the materials have low permeability and durability that is consistent with the time frame required for short-lived radionuclides to decay. Furthermore, cementitious materials can provide a long-term chemical environment that substantially reduces the mobility of some long-lived radionuclides of concern for decommissioning (e.g., C-14, Ni-63, Ni-59). Because of these properties, cementitious materials are common in low-level radioactive waste disposal facilities throughout the world and are an attractive option for entombment of nuclear facilities. This paper describes design considerations for cementitious barriers in the context of performance over time frames of a few hundreds of years (directed toward short-lived radionuclides) and time frames of thousands of years (directed towards longer-lived radionuclides). The emphasis is on providing a n overview of concepts for entombment that take advantage of the properties of cementitious materials and experience from the design of low-level radioactive waste disposal facilities. A few examples of the previous use of cementitious materials for entombment of decommissioned nuclear facilities and proposals for the use in future decommissioning of nuclear reactors in a few countries are also included to provide global perspective.

  2. Entombment Using Cementitious Materials: Design Considerations and International Experience

    International Nuclear Information System (INIS)

    Cementitious materials have physical and chemical properties that are well suited for the requirements of radioactive waste management. Namely, the materials have low permeability and durability that is consistent with the time frame required for short-lived radionuclides to decay. Furthermore, cementitious materials can provide a long-term chemical environment that substantially reduces the mobility of some long-lived radionuclides of concern for decommissioning (e.g., C-14, Ni-63, Ni-59). Because of these properties, cementitious materials are common in low-level radioactive waste disposal facilities throughout the world and are an attractive option for entombment of nuclear facilities. This paper describes design considerations for cementitious barriers in the context of performance over time frames of a few hundreds of years (directed toward short-lived radionuclides) and time frames of thousands of years (directed towards longer-lived radionuclides). The emphasis is on providing a n overview of concepts for entombment that take advantage of the properties of cementitious materials and experience from the design of low-level radioactive waste disposal facilities. A few examples of the previous use of cementitious materials for entombment of decommissioned nuclear facilities and proposals for the use in future decommissioning of nuclear reactors in a few countries are also included to provide global perspective

  3. Alkali-activated slag mortars reinforced with ar glassfibre. Performance and properties

    Directory of Open Access Journals (Sweden)

    Amat, T.

    2006-09-01

    Full Text Available In light of the practical problem posed by the high drying shrinkage rate exhibited by alkali-activated slag (AAS,due to these materials exhibited a high drying shrinkage the present study analyzes the behaviour of alkali-activated slag mortars reinforced with alkali-resistant (AR glass fiber especially designed to reduce drying shrink aging cementitious systems. To this end, both alkali-activated slag and reference Portland cement mortars were prepared, with and without AR fiber (in dosages ranging from 0 to 1.1% by weight of the binder. These mortars were subjected to the following tests: drying shrinkage,mechanical strength after 2, 7 and 28 days, toughness,and high temperature. The microstructure of the materials was also studied by SEM/EDX techniques. At a percentage of 0.22%, AR fiber was found to induce a significant reduction (over 20% in drying shrinkage, without detracting from the fine resistance strength, of alkali activated slag mortar. Moreover, plain activated slag mortars recovered 20% of their initial mechanical strength after exposure to high temperatures, and ins specimens reinforced with glass fiber at a rate of 0.22%,recovery climbed to 50%.El principal problema tecnológico de los cementos de escoria activada alcalinamente (AAS es su elevada retracción al secado. Por ello, en el presente trabajo se estudia el comportamiento de morteros de escoria activada alcalinamente reforzados con fibras de vidrio alcali-resistentes (AR, especialmente diseñadas para reducir la retracción al secado en sistema cementantes. Para ello se prepararon morteros de escoria activada alcalinamente y de cemento Portland como material de referencia. El porcentaje de fibra AR en los morteros varió entre 0-1,1% en peso de ligante. Los morteros preparados fueron sometidos a los siguientes ensayos:retracción al secado, resistencias mecánicas a 2, 7 y 28 días,ensayos de tenacidad, resistencia al impacto y comportamiento resistente frente a altas

  4. Temporary Cementitious Sealers in Enhanced Geothermal Systems

    Energy Technology Data Exchange (ETDEWEB)

    Sugama T.; Pyatina, T.; Butcher, T.; Brothers, L.; Bour, D.

    2011-12-31

    Unlike conventional hydrothennal geothermal technology that utilizes hot water as the energy conversion resources tapped from natural hydrothermal reservoir located at {approx}10 km below the ground surface, Enhanced Geothermal System (EGS) must create a hydrothermal reservoir in a hot rock stratum at temperatures {ge}200 C, present in {approx}5 km deep underground by employing hydraulic fracturing. This is the process of initiating and propagating a fracture as well as opening pre-existing fractures in a rock layer. In this operation, a considerable attention is paid to the pre-existing fractures and pressure-generated ones made in the underground foundation during drilling and logging. These fractures in terms of lost circulation zones often cause the wastage of a substantial amount of the circulated water-based drilling fluid or mud. Thus, such lost circulation zones must be plugged by sealing materials, so that the drilling operation can resume and continue. Next, one important consideration is the fact that the sealers must be disintegrated by highly pressured water to reopen the plugged fractures and to promote the propagation of reopened fractures. In response to this need, the objective of this phase I project in FYs 2009-2011 was to develop temporary cementitious fracture sealing materials possessing self-degradable properties generating when {ge} 200 C-heated scalers came in contact with water. At BNL, we formulated two types of non-Portland cementitious systems using inexpensive industrial by-products with pozzolanic properties, such as granulated blast-furnace slag from the steel industries, and fly ashes from coal-combustion power plants. These byproducts were activated by sodium silicate to initiate their pozzolanic reactions, and to create a cemetitious structure. One developed system was sodium silicate alkali-activated slag/Class C fly ash (AASC); the other was sodium silicate alkali-activated slag/Class F fly ash (AASF) as the binder of temper

  5. Effects of cementitious leachates on the EBS

    Energy Technology Data Exchange (ETDEWEB)

    Koskinen, K.

    2014-01-15

    This report describes the method using which the effects of cement based materials on the engineering barrier system in the repository for spent nuclear fuel planned to Olkiluoto has been assessed. The phenomena considered are degradation of cement based materials due to interaction with groundwater, release of degradation products to groundwater, migration of degradation products in fracture network, interaction of degradation products with rock, and interaction of degradation products with buffer and backfill. Assessment of degradation of cement based materials is based on theories presented in the literature, measurements, and on numerical simulations. Migration of degradation products from the porewater for cementitious materials to the groundwater passing by gives rise to formation of a plume downstream of the material. This plume is comprised of degradation products. The ability of the plume to transport degradation products is assessed using the concept of concentration boundary layers. In the assessment of plume migration in hydraulically active fracture network it has been assumed that the plume does not get mixed with the surrounding groundwater such that the concentrations of the degradation products in the plume remain unaltered. In addition to this, only the transmissivities of various parts of the fracture network limit the migration of the plume. The migration of the plumes is assessed by using the values of known transmissivities in the potential flowpaths. The reactions of the plume with fracture minerals has been assessed, but due to the uncertainties in the parameters used in these assessments the mechanisms potentially decreasing the amounts of degradation products and their concentrations in the plume are not accounted for. Interactions with engineering barrier system are limited to the interactions of the plume with buffers and deposition tunnel backfills. These reactions are not considered in details due to insufficient understanding, but on

  6. EQUIVALENT MODEL OF EXPANSION OF CEMENT MORTAR UNDER SULPHATE EROSION

    Institute of Scientific and Technical Information of China (English)

    Jue Zhu; Minqiang Jiaug; Jiankang Chen

    2008-01-01

    The expansion property of cement mortar under the attack of sulfate ions is studied by experimental and theoretical methods.First,cement mortars are fabricated with the ratio of water to cement of 0.4,0.6,and 0.8.Secondly,the expansion of specimen immerged in sulphate solution is measured at different times.Thirdly,a theoretical model of expansion of cement mortar under sulphate erosion is suggested by virtue of represent volume element method.In this model, the damage evolution due to the interaction between delayed ettringite and cement mortar is taken into account.Finally,the numerical calculation is performed.The numerical and experimental results indicate that the model perfectly describes the expansion of the cement mortar.

  7. Luminescence quartz dating of lime mortars. A first research approach

    International Nuclear Information System (INIS)

    Lime mortars mixed with sand are well suited for connecting structural materials, like stones and bricks, due to the mechanical properties this material exhibits. Their extensive use in architectural and decorative works during the last 4000 years motivated the introduction of the 'Luminescence clock' for age determination of mortars. The same principles as for quartz optically stimulated luminescence (OSL) dating of sediments were applied for age estimation of a mortar fragment removed from a Byzantine church monument dated by archaeological means to 1050-1100 years ago (the first half of the 10th century). The OSL from the quartz was monitored under blue light stimulation and UV detection, using a single-aliquot-regenerative-dose protocol. The quartz-OSL dating of the mortar resulted in 870±230 a. TL polymineral fine grain dating was also performed on a brick fragment which was connected to the mortar, resulting in a TL age of 1095±190 a. (author)

  8. Tailoring of fiber-reinforced cementitious composites (FRCC) for flexural strength and reliability

    Science.gov (United States)

    Obla, Karthikeyan Hariya

    models. In Part II of the thesis an investigation on the use of fibers for reduction of MOR variability of cementitious materials is reported. Specifically, the concept of lowering the sensitivity of MOR to flaw size based on fiber bridging is confirmed with experimental studies of flexural strength of mesh reinforced mortar beams. Variability of composite properties due to variability introduced by fiber itself was identified, and techniques in controlling such variability were introduced. In this connection, the influence of viscosity of the fresh mix on fiber dispersion uniformity was investigated.

  9. Dating mortars: three medieval Spanish architectures

    Directory of Open Access Journals (Sweden)

    Quirós Castillo, Juan Antonio

    2011-12-01

    Full Text Available One of the major issues in building archaeology is finding the age of elements and structures discovered. Mortars represent a class of material basically constituted by a mixture of different phases (i.e. binder, aggregates, water and are widely used for constructive uses and artworks. Current scientific literature regarding the possibility of accurate radiocarbon dating for mortars reports different and still contradictory results. In this study, a new protocol for radiocarbon dating of mortar developed at the Centre for Isotopic Research on Cultural and Environmental heritage (CIRCE is used to perform 14C measurements on archaeological mortars coming from three medieval architectures of northern Spain (two churches and the walls of a castle. Results observed will be discussed and compared with independent age estimations (i.e. radiocarbon dating performed on organic materials found in the same study site, archaeological analyses in order to frame experimental observations in the actual site knowledge by means of a multidisciplinary approach.Una de las principales problemáticas a las que se enfrenta la arqueología de la arquitectura es datar los elementos y las estructuras. Las argamasas son un tipo de material constituido por una mezcla de diferentes elementos (agregados, agua y empleadas en muchos tipos de construcciones. Los estudios realizados hasta la actualidad en torno a la posibilidad de realizar dataciones radiocarbónicas precisas han proporcionado resultados contradictorios. El objetivo de este artículo es el de presentar un nuevo protocolo para datar la arquitectura histórica desarrollado por el Centre for Isotopic Research on Cultural and Enviromental Heritage (CIRCE, basado en la realización de dataciones radiocarbónicas de argamasas a partir del análisis de tres arquitecturas medievales del norte del España, dos iglesias y la muralla de un castillo. Los resultados obtenidos han sido confrontados y comparados con otros

  10. Study on cementitious properties of steel slag

    Directory of Open Access Journals (Sweden)

    Zhu G.

    2013-01-01

    Full Text Available The converter steel slag chemical and mineral components in China’s main steel plants have been analysed in the present paper. The electronic microscope, energy spectrum analysis, X-ray diffraction analysis confirmed the main mineral compositions in the converter slag. Converter slag of different components were grounded to obtain a powder with specific surface area over 400m2/kg, making them to take place some part of the cement in the concrete as the admixture and carry out the standard tests. The results indicate that the converter slag can be used as cementitious materials for construction. Furthermore, physical mechanic and durability tests on the concrete that certain amount of cement be substituted by converter steel slag powder from different steel plants are carried out, the results show that the concrete with partial substitution of steel slag powder has the advantages of higher later period strength, better frost resistance, good wear resistance and lower hydration heat, etc. This study can be used as the technical basis for “Steel Slag Powder Used For Cement And Concrete”, “Steel Slag Portland Cement”, “Low Heat Portland Steel Slag Cement”, “Steel Slag Road Cement” in China, as well as a driving force to the works of steel slag utilization with high-value addition, circular economy, energy conservation and discharge reduction in the iron and steel industry.

  11. Acoustic Emission Monitoring of Cementitious Wasteforms

    International Nuclear Information System (INIS)

    A summary is presented of the potential of non-destructive acoustic emission (AE) method to be applied for structures immobilising nuclear wastes. The use and limitations of the method are discussed with given examples of experimental configurations and results obtained from AE monitoring and data analysis of two different processes addressing particular issues related to the nuclear waste immobilisation. These are (a) corrosion of aluminium, classified as intermediate level waste (ILW) in the UK, encapsulated in cementitious structures and (b) partial melting and solidification during cooling of granite at a pressure of 0.15 GPa which simulates the conditions in a deep borehole disposal of canisters of vitrified high level waste (HLW). Methodology for analysis of the collected data and characterisation of the potential AE sources is performed at different steps including simple signals count and more complex signal parameter-based approach and advanced signal processing. The AE method has been shown as a potential tool for monitoring and inspection of structures immobilising nuclear wastes in relation to the time progress of different interactions of the waste with the encapsulating matrix or the wasteform with the hosting environment for permanent disposal. (author)

  12. Cementitious waste option scoping study report

    International Nuclear Information System (INIS)

    A Settlement Agreement between the Department of Energy (DOE) and the State of Idaho mandates that all high-level radioactive waste (HLW) now stored at the Idaho Chemical Processing Plant (ICPP) on the Idaho National Engineering and Environmental Laboratory (INEEL) will be treated so that it is ready to be moved out of Idaho for disposal by a target date of 2035. This study investigates the nonseparations Cementitious Waste Option (CWO) as a means to achieve this goal. Under this option all liquid sodium-bearing waste (SBW) and existing HLW calcine would be recalcined with sucrose, grouted, canisterized, and interim stored as a mixed-HLW for eventual preparation and shipment off-Site for disposal. The CWO waste would be transported to a Greater Confinement Disposal Facility (GCDF) located in the southwestern desert of the US on the Nevada Test Site (NTS). All transport preparation, shipment, and disposal facility activities are beyond the scope of this study. CWO waste processing, packaging, and interim storage would occur over a 5-year period between 2013 and 2017. Waste transport and disposal would occur during the same time period

  13. Cementitious waste option scoping study report

    Energy Technology Data Exchange (ETDEWEB)

    Lee, A.E.; Taylor, D.D.

    1998-02-01

    A Settlement Agreement between the Department of Energy (DOE) and the State of Idaho mandates that all high-level radioactive waste (HLW) now stored at the Idaho Chemical Processing Plant (ICPP) on the Idaho National Engineering and Environmental Laboratory (INEEL) will be treated so that it is ready to be moved out of Idaho for disposal by a target date of 2035. This study investigates the nonseparations Cementitious Waste Option (CWO) as a means to achieve this goal. Under this option all liquid sodium-bearing waste (SBW) and existing HLW calcine would be recalcined with sucrose, grouted, canisterized, and interim stored as a mixed-HLW for eventual preparation and shipment off-Site for disposal. The CWO waste would be transported to a Greater Confinement Disposal Facility (GCDF) located in the southwestern desert of the US on the Nevada Test Site (NTS). All transport preparation, shipment, and disposal facility activities are beyond the scope of this study. CWO waste processing, packaging, and interim storage would occur over a 5-year period between 2013 and 2017. Waste transport and disposal would occur during the same time period.

  14. Impact of cementitious materials decalcification on transfer properties: application to radioactive waste deep repository; Influence de la decalcification de materiaux cimentaires sur les proprietes de transfert: application au stockage profond de dechets radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Perlot, C

    2005-09-15

    Cementitious materials have been selected to compose the engineering barrier system (EBS) of the French radioactive waste deep repository, because of concrete physico-chemical properties: the hydrates of the cementitious matrix and the pH of the pore solution contribute to radionuclides retention; furthermore the compactness of these materials limits elements transport. The confinement capacity of the system has to be assessed while a period at least equivalent to waste activity (up to 100.000 years). His durability was sustained by the evolution of transfer properties in accordance with cementitious materials decalcification, alteration that expresses structure long-term behavior. Then, two degradation modes were carried out, taking into account the different physical and chemical solicitations imposed by the host formation. The first mode, a static one, was an accelerated decalcification test using nitrate ammonium solution. It replicates the EBS alteration dues to underground water. Degradation kinetic was estimated by the amount of calcium leached and the measurement of the calcium hydroxide dissolution front. To evaluate the decalcification impact, samples were characterized before and after degradation in term of microstructure (porosity, pores size distribution) and of transfer properties (diffusivity, gas and water permeability). The influence of cement nature (ordinary Portland cement, blended cement) and aggregates type (lime or siliceous) was observed: experiments were repeated on different mortars mixes. On this occasion, an essential reflection on this test metrology was led. The second mode, a dynamical degradation, was performed with an environmental permeameter. It recreates the EBS solicitations ensured during the re-saturation period, distinguished by the hydraulic pressure imposed by the geologic layer and the waste exothermicity. This apparatus, based on triaxial cell functioning, allows applying on samples pressure drop between 2 and 10 MPa and

  15. Photovoltaic's silica-rich waste sludge as supplementary cementitious material (SCM)

    International Nuclear Information System (INIS)

    Waste sludge, a solid recovered from wastewater of photovoltaic-industries, composes of agglomerates of nano-particles like SiO2 and CaCO3. This sludge deflocculates in aqueous solutions into nano-particles smaller than 1 μm. Thus, this sludge constitutes a potentially hazardous waste when it is improperly disposed. Due to its high content of amorphous SiO2, this sludge has a potential use as supplementary cementitious material (SCM) in concrete. In this study the main properties of three different samples of photovoltaic's silica-rich waste sludge (nSS) were physically and chemically characterized. The characterization techniques included: scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), nitrogen physical adsorption isotherm (BET method), density by Helium pycnometry, particle size distribution determined by laser light scattering (LLS) and zeta-potential measurements by dynamic light scattering (DLS). In addition, a dispersability study was performed to design stable slurries to be used as liquid additives for the concrete production on site. The effects on the hydration kinetics of cement pastes by the incorporation of nSS in the designed slurries were determined using an isothermal calorimeter. A compressive strength test of standard mortars with 7% of cement replacement was performed to determine the pozzolanic activity of the waste nano-silica sludge. Finally, the hardened system was fully characterized to determine the phase composition. The results demonstrate that the nSS can be utilized as SCM to replace portion of cement in mortars, thereby decreasing the CO2 footprint and the environmental impact of concrete. -- Highlights: •Three different samples of PV nano-silica sludge (nSS) were fully characterized. •nSS is composed of agglomerates of nano-particles like SiO2 and CaCO3. •Dispersability studies demonstrated that nSS agglomerates are broken to nano-size. •nSS can be classified as a

  16. Synthesis of a Cementitious Material Nanocement Using Bottom-Up Nanotechnology Concept: An Alternative Approach to Avoid CO2 Emission during Production of Cement

    Directory of Open Access Journals (Sweden)

    Byung Wan Jo

    2014-01-01

    Full Text Available The world’s increasing need is to develop smart and sustainable construction material, which will generate minimal climate changing gas during their production. The bottom-up nanotechnology has established itself as a promising alternative technique for the production of the cementitious material. The present investigation deals with the chemical synthesis of cementitious material using nanosilica, sodium aluminate, sodium hydroxide, and calcium nitrate as reacting phases. The characteristic properties of the chemically synthesized nanocement were verified by the chemical composition analysis, setting time measurement, particle size distribution, fineness analysis, and SEM and XRD analyses. Finally, the performance of the nanocement was ensured by the fabrication and characterization of the nanocement based mortar. Comparing the results with the commercially available cement product, it is demonstrated that the chemically synthesized nanocement not only shows better physical and mechanical performance, but also brings several encouraging impacts to the society, including the reduction of CO2 emission and the development of sustainable construction material. A plausible reaction scheme has been proposed to explain the synthesis and the overall performances of the nanocement.

  17. Damage detection in concrete and cementitious composites

    Science.gov (United States)

    Wu, Hwai-Chung; Pai, P. Frank

    2008-03-01

    Traditionally ultrasonic testing is used to estimate the extent of damage in a concrete structure. However Pulse-velocity and amplitude attenuation methods are not very reliable, and are difficult to reveal early damage of concrete. In a previous study, a new active modulation approach, Nonlinear Active Wave Modulation Spectroscopy, was developed and found promising for early detection of damage in concrete. In this procedure, a probe wave is passed through the system in a fashion similar to regular acoustic methods for inspection. Simultaneously, a second, low-frequency modulating wave is applied to the system to effectively change the size and stiffness of flaws microscopically and cyclically, thereby causing the frequency modulation to change cyclically as well. It has been also shown that it is advantageous to apply the Hilbert-Huang transform to decompose nonlinear non-stationary time-domain responses of plain concrete. Such procedure leads to improving the damage detection sensitivity of this modulation method in concrete. In this paper, further investigation on mortar and fiber reinforced concrete will be presented and discussed.

  18. DEMONSTRATION OF LEACHXS/ORCHESTRA CAPABILITIES BY SIMULATING CONSTITUENT RELEASE FROM A CEMENTITIOUS WASTE FORM IN A REINFORCED CONCRETE VAULT

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C.; Meeussen, J.; Sloot, H.

    2010-03-31

    The objective of the work described in this report is to demonstrate the capabilities of the current version of LeachXS{trademark}/ORCHESTRA for simulating chemical behavior and constituent release processes in a range of applications that are relevant to the CBP. This report illustrates the use of LeachXS{trademark}/ORCHESTRA for the following applications: (1) Comparing model and experimental results for leaching tests for a range of cementitious materials including cement mortars, grout, stabilized waste, and concrete. The leaching test data includes liquid-solid partitioning as a function of pH and release rates based on laboratory column, monolith, and field testing. (2) Modeling chemical speciation of constituents in cementitious materials, including liquid-solid partitioning and release rates. (3) Evaluating uncertainty in model predictions based on uncertainty in underlying composition, thermodynamic, and transport characteristics. (4) Generating predominance diagrams to evaluate predicted chemical changes as a result of material aging using the example of exposure to atmospheric conditions. (5) Modeling coupled geochemical speciation and diffusion in a three layer system consisting of a layer of Saltstone, a concrete barrier, and a layer of soil in contact with air. The simulations show developing concentration fronts over a time period of 1000 years. (6) Modeling sulfate attack and cracking due to ettringite formation. A detailed example for this case is provided in a separate article by the authors (Sarkar et al. 2010). Finally, based on the computed results, the sensitive input parameters for this type of modeling are identified and discussed. The chemical speciation behavior of substances is calculated for a batch system and also in combination with transport and within a three layer system. This includes release from a barrier to the surrounding soil as a function of time. As input for the simulations, the physical and chemical properties of the

  19. Thermal conductivity and other properties of cementitious grouts

    Energy Technology Data Exchange (ETDEWEB)

    Allan, M.

    1998-08-01

    The thermal conductivity and other properties cementitious grouts have been investigated in order to determine suitability of these materials for grouting vertical boreholes used with geothermal heat pumps. The roles of mix variables such as water/cement ratio, sand/cement ratio and superplasticizer dosage were measured. In addition to thermal conductivity, the cementitious grouts were also tested for bleeding, permeability, bond to HDPE pipe, shrinkage, coefficient of thermal expansion, exotherm, durability and environmental impact. This paper summarizes the results for selected grout mixes. Relatively high thermal conductivities were obtained and this leads to reduction in predicted bore length and installation costs. Improvements in shrinkage resistance and bonding were achieved.

  20. THERMAL CONDUCTIVITY AND OTHER PROPERTIES OF CEMENTITIOUS GROUTS

    Energy Technology Data Exchange (ETDEWEB)

    ALLAN,M.

    1998-05-01

    The thermal conductivity and other properties cementitious grouts have been investigated in order to determine suitability of these materials for grouting vertical boreholes used with geothermal heat pumps. The roles of mix variables such as water/cement ratio, sand/cement ratio and superplasticizer dosage were measured. In addition to thermal conductivity, the cementitious grouts were also tested for bleeding, permeability, bond to HDPE pipe, shrinkage, coefficient of thermal expansion, exotherm, durability and environmental impact. This paper summarizes the results for selected grout mixes. Relatively high thermal conductivities were obtained and this leads to reduction in predicted bore length and installation costs. Improvements in shrinkage resistance and bonding were achieved.

  1. Cementitious Barriers Partnership Accomplishments And Relevance To The DOE Complex

    International Nuclear Information System (INIS)

    The Cementitious Barriers Partnership (CBP) was initiated to reduce risk and uncertainties in the performance assessments that directly impact U.S. Department of Energy (DOE) environmental cleanup and closure programs. The CBP is supported by the DOE Office of Environmental Management (DOE-EM) and has been specifically addressing the following critical EM program needs: (i) the long-term performance of cementitious barriers and materials in nuclear waste disposal facilities and (ii) increased understanding of contaminant transport behavior within cementitious barrier systems to support the development and deployment of adequate closure technologies. To accomplish this, the CBP has two initiatives: (1) an experimental initiative to increase understanding of changes in cementitious materials over long times (> 1000 years) over changing conditions and (2) a modeling initiative to enhance and integrate a set of computational tools validated by laboratory and field experimental data to improve understanding and prediction of the long-term performance of cementitious barriers and waste forms used in nuclear applications. In FY10, the CBP developed the initial phase of an integrated modeling tool that would serve as a screening tool which could help in making decisions concerning disposal and tank closure. The CBP experimental programs are underway to validate this tool and provide increased understanding of how CM changes over time and under changing conditions. These initial CBP products that will eventually be enhanced are anticipated to reduce the uncertainties of current methodologies for assessing cementitious barrier performance and increase the consistency and transparency of the DOE assessment process. These tools have application to low activity waste forms, high level waste tank closure, D and D and entombment of major nuclear facilities, landfill waste acceptance criteria, and in-situ grouting and immobilization of vadose zone contamination. This paper

  2. Obtaining cementitious material from municipal solid waste

    Directory of Open Access Journals (Sweden)

    Macías, A.

    2007-06-01

    Full Text Available The primary purpose of the present study was to determine the viability of using incinerator ash and slag from municipal solid waste as a secondary source of cementitious materials. The combustion products used were taken from two types of Spanish MSW incinerators, one located at Valdemingómez, in Madrid, and the other in Melilla, with different incineration systems: one with fluidised bed combustion and other with mass burn waterwall. The effect of temperature (from 800 to 1,200 ºC on washed and unwashed incinerator residue was studied, in particular with regard to phase formation in washed products with a high NaCl and KCl content. The solid phases obtained were characterized by X-ray diffraction and BET-N2 specific surface procedures.El principal objetivo del trabajo ha sido determinar la viabilidad del uso de las cenizas y escorias procedentes de la incineración de residuos sólidos urbanos, como materia prima secundaria para la obtención de fases cementantes. Para ello se han empleado los residuos generados en dos tipos de incineradoras españolas de residuos sólidos urbanos: la incineradora de Valdemingómez y la incineradora de Melilla. Se ha estudiado la transformación de los residuos, sin tratamiento previo, en función de la temperatura de calentamiento (desde 800 ºC hasta 1.200 ºC, así como la influencia del lavado de los residuos con alto contenido en NaCl y KCl en la formación de fases obtenidas a las diferentes temperaturas de calcinación. Las fases obtenidas fueron caracterizadas por difracción de rayos X y área superficial por el método BET-N2.

  3. A new and superior ultrafine cementitious grout

    International Nuclear Information System (INIS)

    Sealing fractures in nuclear waste repositories concerns all programs investigating deep burial as a means of disposal. Because the most likely mechanism for contaminant migration is by dissolution and movement through groundwater, sealing programs are seeking low-viscosity sealants that are chemically, mineralogically, and physically compatible with the host rock. This paper presents the results of collaborative work directed by Sandia National Laboratories (SNL) and supported by Whiteshell Laboratories, operated by Atomic Energy of Canada, Ltd. The work was undertaken in support of the Waste Isolation Pilot Plant (WIPP), an underground nuclear waste repository located in a salt formation east of Carlsbad, NM. This effort addresses the technology associated with long-term isolation of nuclear waste in a natural salt medium. The work presented is part of the WIPP plugging and sealing program, specifically the development and optimization of an ultrafine cementitious grout that can be injected to lower excessive, strain-induced hydraulic conductivity in the fractured rock termed the Disturbed Rock Zone (DRZ) surrounding underground excavations. Innovative equipment and procedures employed in the laboratory produced a usable cement-based grout; 90% of the particles were smaller than 8 microns and the average particle size was 4 microns. The process involved simultaneous wet pulverization and mixing. The grout was used for a successful in situ test underground at the WIPP. Injection of grout sealed microfractures as small as 6 microns (and in one rare instance, 3 microns) and lowered the gas transmissivity of the DRZ by up to three orders of magnitude. Following the WIPP test, additional work produced an improved version of the grout containing particles 90% smaller than 5 microns and averaging 2 microns. This grout will be produced in dry form, ready for the mixer

  4. The immobilisation of clinoptilolite within cementitious systems

    International Nuclear Information System (INIS)

    The zeolitic ion exchanger clinoptilolite was encapsulated within various cementitious systems in order to assess their suitability for the retention of the radioelements, Cs and Sr. The pozzolanic reaction of clinoptilolite is reduced in composites containing BFS and PFA and appears not to continue after 7 days of hydration. Ca(OH)2 persists up to 360 days of hydration in a 9:1BFS:OPC system with 10% clinoptilolite added, despite the presence of unreacted pozzolana. This may be due to low pH of the pore solution, if Na and K act as counter cations in the aluminous C-S-H, a product of pozzolanic hydration or are exchanged onto the clinoptilolite. Saturation of the pore solution with Ca may prevent further dissolution of Ca(OH)2. Cs leaching occurs in all samples during accelerated tests due to breakdown of the clinoptilolite structure. The alternative cement system calcium sulfo-aluminate cement (CSA) has a different hydration chemistry and properties to OPC and OPC composites with a lower pore solution pH. Clinoptilolite appears to react in a hydrating CSA system with significant reaction continuing between 28 and 90 days of hydration. Leaching of Cs from CSA is higher than from an OPC system, in which almost all of the clinoptilolite crystallinity is lost. The major product of CSA hydration is ettringite. Cs may be adsorbed within cation sites of the C-S-H in an OPC system but not by ettringite which does not retain Cs so Cs has high mobility and leachability through the CSA matrix. (authors)

  5. Composition of mortar as a function of distance to the brick-mortar interface : A study on the formation of cured mortar structure in masonry using NMR, PFM and XRD

    NARCIS (Netherlands)

    Brocken, H.J.P.; Larbi, J.A.; Pel, L.; Pers, N.M. van der

    1999-01-01

    The formation of cured mortar structure in masonry was studied using multiple experimental techniques. Starting with fresh mortar, nuclear magnetic resonance (NMR) was used to measure the water extraction during brick laying. After curing, the composition of cured mortar was investigated with polari

  6. Composition of mortar as a function of distance to the brick-mortar interface: A study on the formation of cured mortar structure in masonry using NMR, PFM and XRD

    NARCIS (Netherlands)

    Brocken, H.J.P.; Larbi, J.A.; Pel, L.; Van der Pers, N.M.

    1999-01-01

    The formation of cured mortar structure in masonry was studied using multiple experimental techniques. Starting with fresh mortar, nuclear magnetic resonance (NMR) was used to measure the water extraction during brick laying. After curing, the composition of cured mortar was investigated with polari

  7. The colour potentials of SSA-containing mortar

    DEFF Research Database (Denmark)

    Kappel, Annemette; Ottosen, Lisbeth M.; Kirkelund, Gunvor Marie;

    2015-01-01

    few exceptions landfilled and thus, wasted.The purpose of the experiments was to examine the influence of SSA and how it affected the colour of mortar samples. SSA was ground in 6 different intervals and added to mortar mixes by replacing 20% of the cement. An additional focus was to examine the...... possibilities to accentuate the colours of the hardened mortar by using paper cuttings in the production of the samples. The result of the experiments showed that a colour scale can be developed from ground SSA, and that paper may have the potential of providing divers textural qualities when it is used in...

  8. Combined meso-scale modeling and experimental investigation of the effect of mechanical damage on the transport properties of cementitious composites

    Science.gov (United States)

    Raghavan, Balaji; Niknezhad, Davood; Bernard, Fabrice; Kamali-Bernard, Siham

    2016-09-01

    The transport properties of cementitious composites such as concrete are important indicators of their durability, and are known to be heavily influenced by mechanical loading. In the current work, we use meso-scale hygro-mechanical modeling with a morphological 3D two phase mortar-aggregate model, in conjunction with experimentally obtained properties, to investigate the coupling between mechanical loading and damage and the permeability of the composite. The increase in permeability of a cylindrical test specimen at 28% aggregate fraction during a uniaxial displacement-controlled compression test at 85% of the peak load was measured using a gas permeameter. The mortar's mechanical behavior is assumed to follow the well-known compression damaged plasticity (CDP) model with isotropic damage, at varying thresholds, and obtained from different envelope curves. The damaged intrinsic permeability of the mortar evolves according to a logarithmic matching law with progressive loading. We fit the matching law parameters to the experimental result for the test specimen by inverse identification using our meso-scale model. We then subject a series of virtual composite specimens to quasi-static uniaxial compressive loading with varying boundary conditions to obtain the simulated damage and strain evolutions, and use the damage data and the previously identified parameters to determine the evolution of the macroscopic permeability tensor for the specimens, using a network model. We conduct a full parameter study by varying aggregate volume fraction, granulometric distribution, loading/boundary conditions and "matching law" parameters, as well as for different strain-damage thresholds and uniaxial loading envelope curves. Based on this study, we propose Avrami equation-based upper and lower bounds for the evolution of the damaged permeability of the composite.

  9. Significance of steel electrical resistance method in the evaluation of reinforcement corrosion in cementitious systems

    Directory of Open Access Journals (Sweden)

    Krajci, L.

    2004-06-01

    Full Text Available The suitable detection system of steel reinforcement corrosion in concrete structures contributes to the reduction of their maintenance costs. Method of steel electrical resistance represents non-destructive monitoring of steel in cementitious systems. Specially prepared and arranged test specimen of steel as a corrosion sensor is embedded in mortar specimen. Verification tests of this method based on chloride corrosion of steel in mortars as well as its visual inspection are introduced. Significance of steel electrical resistance method lies in the expression of steel corrosion by these quantitative parameters: reduction of cross-section of steel, thickness of corroded layer and loss of weight of steel material. This method is an integral method that allows the indirect determination of mentioned corrosion characteristics. The comparison of verified method with gravimetric evaluation of steel corrosion gives a good correspondence. Test results on mortars with calcium chloride dosages between 0.5% and 4.0% by weight of cement prove high sensitiveness and reliability of steel electrical resistance method.

    La utilización de un sistema de detección de la corrosión de las armaduras en estructuras de hormigón puede contribuir a la reducción de sus costes de mantenimiento. El método de la resistencia eléctrica del acero consiste en la monitorización no-destructiva realizada sobre el acero en sistemas cementantes. Dentro de la muestra de mortero se coloca el sistema de detección, especialmente preparado y fijado, actuando como un sensor de la corrosión. En este trabajo se presentan ensayos de verificación de este método, junto con inspecciones visuales, en morteros sometidos a corrosión de armaduras por efecto de los cloruros. La efectividad de este método de la resistencia eléctrica del acero se expresa, en la corrosión de armaduras, de acuerdo a los siguientes parámetros cuantitativos: reducción de la sección transversal del

  10. A chemometric approach to the characterisation of historical mortars

    International Nuclear Information System (INIS)

    The compositional knowledge of historical mortars is of great concern in case of provenance and dating investigations and of conservation works since the nature of the raw materials suggests the most compatible conservation products. The classic characterisation usually goes through various analytical determinations, while conservation laboratories call for simple and quick analyses able to enlighten the nature of mortars, usually in terms of the binder fraction. A chemometric approach to the matter is here undertaken. Specimens of mortars were prepared with calcitic and dolomitic binders and analysed by Atomic Spectroscopy. Principal Components Analysis (PCA) was used to investigate the features of specimens and samples. A Partial Least Square (PLS1) regression was done in order to predict the binder/aggregate ratio. The model was applied to historical mortars from the churches of St. Lorenzo (Milan) and St. Abbondio (Como). The accordance between the predictive model and the real samples is discussed

  11. Atmospheric deterioration of ancient and modern hydraulic mortars

    Science.gov (United States)

    Sabbioni, C.; Zappia, G.; Riontino, C.; Blanco-Varela, M. T.; Aguilera, J.; Puertas, F.; Balen, K. Van; Toumbakari, E. E.

    Different types of ancient and recent hydraulic mortars were collected from well-documented archaeological, historic and modern buildings in various geographical locations (urban, suburban, rural and maritime) of Italy, Spain and Belgium, representative of different environmental impacts, types and degrees of deterioration. A synthesis of the characteristics of the collected samples is presented, along with the identification of the formation products that occurred on the sample surfaces as a result of the reaction of the mortars with atmospheric pollutants. The analyses were performed by means of optical microscopy (OM), X-ray diffractometry (XRD), scanning electron microscopy (SEM-EDX) and ion chromatography (IC). The results obtained prove that sulphation processes takes place on hydraulic mortars, leading to gypsum formation on the external surface of the samples. Through the reaction of gypsum with the aluminate hydrate of the binder, ettringite formation was found to occur on a cement-based restoration mortar sampled in Antwerp.

  12. Tangential adhesion strength of cement mortars in masonry

    Directory of Open Access Journals (Sweden)

    Derkach V.N.

    2012-05-01

    Full Text Available The initial shear strength (tangential adhesion and the angle of internal friction in the horizontal plane of mortar joints are among important characteristics, determining the masonry strength and stiffness qualities in case of share. These characteristics influence largely over the limit state approach of buildings and facilities during seismic activity and over wind, crane and other load, causing the panel frame distortion in frame buildings with masonry infill.In the paper the experimental studies results of tangential adhesion strength of cement mortars with solid and hollow ceramic bricks, porous stones, calcium silicate bricks and cellular concrete blocks are presented. This research gives experimental dependences of mortar adhesive strength with mentioned types of masonry units on compressive strength of cement mortar. There is also the comparison of the obtained results with Russian and foreign standards in this paper.

  13. Optimization Problem of Mortar Barrel and Bomb Clearances

    Directory of Open Access Journals (Sweden)

    J. P. Sirpal

    1987-07-01

    Full Text Available Optimum mortar windage to achieve maximum accuracy and required velocity for impacting the firing stud under two conditions of constraint is considered. These control constraints are considered to be bounded and the extremals have been studied.

  14. Influences of Carboxyl Methyl Cellulose on Performances of Mortar

    Institute of Scientific and Technical Information of China (English)

    WANG Yuli; ZHOU Mingkai; SHAN Junhong; XU Fang; YANG Yuhui

    2007-01-01

    Carboxyl methyl cellulose (CMC) was mixed into mortar to improve the waterretention performance of mortar, the quality of floated coat of aerated concrete became better. The consistency and compression strength of mortar with CMC were studied. The water absorption was studied with the method of filter paper. The micro mechanism was researched with X-ray diffraction and scanning electron microscopy(SEM). The experimental results show the water-holding performance of mortar with CMC is largely improved and it is better when the mixed amount is about 1.5%; the compression strength had a descending trend with the increase of CMC; CMC reacted with calcium hydroxide(CH) into the deposition of calcium carboxyl methyl cellulose.

  15. Service life prediction and fibre reinforced cementitious composites

    DEFF Research Database (Denmark)

    Stoklund Larsen, E.

    , the factors affecting the pure cementitious composite are described. Different sizes and types of fibre reinforced crmentitious composites have been chosen to illustrate different ageing and deterioration mechanisms. Some ageing mechanisms can be accelerated and others cannot which is demonstrated in...

  16. REFERENCE CASES FOR USE IN THE CEMENTITIOUS BARRIERS PARTNERSHIP

    International Nuclear Information System (INIS)

    The Cementitious Barriers Project (CBP) is a multidisciplinary cross cutting project initiated by the US Department of Energy (DOE) to develop a reasonable and credible set of tools to improve understanding and prediction of the structural, hydraulic and chemical performance of cementitious barriers used in nuclear applications. The period of performance is >100 years for operating facilities and > 1000 years for waste management. The CBP has defined a set of reference cases to provide the following functions: (1) a common set of system configurations to illustrate the methods and tools developed by the CBP, (2) a common basis for evaluating methodology for uncertainty characterization, (3) a common set of cases to develop a complete set of parameter and changes in parameters as a function of time and changing conditions, and (4) a basis for experiments and model validation, and (5) a basis for improving conceptual models and reducing model uncertainties. These reference cases include the following two reference disposal units and a reference storage unit: (1) a cementitious low activity waste form in a reinforced concrete disposal vault, (2) a concrete vault containing a steel high-level waste tank filled with grout (closed high-level waste tank), and (3) a spent nuclear fuel basin during operation. Each case provides a different set of desired performance characteristics and interfaces between materials and with the environment. Examples of concretes, grout fills and a cementitious waste form are identified for the relevant reference case configurations

  17. Engineered cementitious composites for strengthening masonry infilled reinforced concrete frames

    DEFF Research Database (Denmark)

    Dehghani, Ayoub; Nateghi-Alahi, Fariborz; Fischer, Gregor

    2015-01-01

    The results of the second part of a comprehensive experimental program, aimed at investigating the behavior of masonry infilled reinforced concrete (RC) frames strengthened with fiber reinforced engineered cementitious composites (ECC) used as an overlay on the masonry wall, are presented in this...

  18. Ancient analogues concerning stability and durability of cementitious wasteform

    International Nuclear Information System (INIS)

    The history of cementitious materials goes back to ancient times. The Greeks and Romans used calcined limestone and later developed pozzolanic cement by grinding together lime and volcanic ash called open-quotes pozzolanclose quotes which was first found near Port Pozzuoli, Italy. The ancient Chinese used lime-pozzolanic mixes to build the Great Wall. The ancient Egyptians used calcined impure gypsum to build the Great Pyramid of Cheops. The extraordinary stability and durability of these materials has impressed us, when so much dramatically damaged infrastructure restored by using modern portland cement now requires rebuilding. Stability and durability of cementitious materials have attracted intensive research interest and contractors' concerns, as does immobilization of radioactive and hazardous industrial waste in cementitious materials. Nuclear waste pollution of the environment and an acceptable solution for waste management and disposal constitute among the most important public concerns. The analogy of ancient cementitious materials to modern Portland cement could give us some clues to study their stability and durability. This present study examines selected results of studies of ancient building materials from France, Italy, China, and Egypt, combined with knowledge obtained from the behavior of modern portland cement to evaluate the potential for stability and durability of such materials in nuclear waste forms

  19. Thermodynamics of Autogenous Self-healing in Cementitious Materials

    NARCIS (Netherlands)

    Huang, H.

    2014-01-01

    Concrete is a brittle composite cementitious material that easily fractures under tensile loading. Microcracks can appear throughout the concrete prior to application of any load because of temperature-induced strain and autogenous and drying shrinkage. There is no doubt that these cracks provide pr

  20. REFERENCE CASES FOR USE IN THE CEMENTITIOUS BARRIERS PARTNERSHIP

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C

    2009-01-06

    The Cementitious Barriers Project (CBP) is a multidisciplinary cross cutting project initiated by the US Department of Energy (DOE) to develop a reasonable and credible set of tools to improve understanding and prediction of the structural, hydraulic and chemical performance of cementitious barriers used in nuclear applications. The period of performance is >100 years for operating facilities and > 1000 years for waste management. The CBP has defined a set of reference cases to provide the following functions: (1) a common set of system configurations to illustrate the methods and tools developed by the CBP, (2) a common basis for evaluating methodology for uncertainty characterization, (3) a common set of cases to develop a complete set of parameter and changes in parameters as a function of time and changing conditions, and (4) a basis for experiments and model validation, and (5) a basis for improving conceptual models and reducing model uncertainties. These reference cases include the following two reference disposal units and a reference storage unit: (1) a cementitious low activity waste form in a reinforced concrete disposal vault, (2) a concrete vault containing a steel high-level waste tank filled with grout (closed high-level waste tank), and (3) a spent nuclear fuel basin during operation. Each case provides a different set of desired performance characteristics and interfaces between materials and with the environment. Examples of concretes, grout fills and a cementitious waste form are identified for the relevant reference case configurations.

  1. A Plastic Damage Mechanics Model for Engineered Cementitious Composites

    DEFF Research Database (Denmark)

    Dick-Nielsen, Lars; Stang, Henrik; Poulsen, Peter Noe; Kabele, Petr

    This paper discusses the establishment of a plasticity-based damage mechanics model for Engineered Cementitious Composites (ECC). The present model differs from existing models by combining a matrix and fiber description in order to describe the behavior of the ECC material. The model provides...

  2. Characteristics of Bamboo Leaf Ash Blended Cement Paste and Mortar

    OpenAIRE

    Umoh A.A.; Odesola I.

    2015-01-01

    The use of bamboo leaf ash as cement supplement can contribute to reduction in cost and environmental hazard associated with cement production as well as waste pollution caused by the littered bamboo leaves. Therefore, the characteristics of cement paste and mortar incorporating bamboo leaf ash were investigated. The results of the physical properties of the pastes were within the requirements stipulated by relevant standards while that of the mortar cubes indicated that the compressive stren...

  3. Strengthening of poor lime mortar with consolidation agents

    Czech Academy of Sciences Publication Activity Database

    Slížková, Zuzana; Frankeová, Dita; Drdácký, Miloš

    Glasgow: University of the West of Scotland, 2013 - (Hughes, J.) ISBN 978-1-903978-44-3. [Historic mortars conference /3./. Glasgow (GB), 11.09.2013-13.09.2013] R&D Projects: GA ČR(CZ) GA103/09/2067; GA MŠk(CZ) ED1.1.00/02.0060 Institutional support: RVO:68378297 Keywords : mortar * consolidation * strengthening * treatment * consolidant Subject RIV: JN - Civil Engineering

  4. The colour potentials of SSA-containing mortar

    OpenAIRE

    Kappel, Annemette; Ottosen, Lisbeth M.; Kirkelund, Gunvor Marie; Bache, Anja Margrethe; Goltermann, Per

    2015-01-01

    This paper reports an experimental study of aesthetical qualities of mortar containing sewage sludgeash (SSA). SSA is the residue produced at water treatment plants where incineration of the sludge is applied in order to decrease volume and to prevent pathogens from spreading. Today SSA is with a few exceptions landfilled and thus, wasted.The purpose of the experiments was to examine the influence of SSA and how it affected the colour of mortar samples. SSA was ground in 6 different intervals...

  5. Mørtelegenskaber og billedbehandling (Mortar properties and image processing)

    DEFF Research Database (Denmark)

    Nielsen, Anders

    1998-01-01

    The properties of lime mortars can be essentially improved by adding fillers to the mortars in an intelligent way. This is shown in the thesis of Thorborg von Konow (1997).The changes in the pore structure and the following changes in properties can be treated by means of the rules in materials m...... mechanics developed by Lauge Fuglsang Nielsen on this institute. The necessary pore characteristics are measured by means of image processing....

  6. Neutron radiography of heated high-performance mortar

    OpenAIRE

    Weber B; Wyrzykowski M.; Griffa M.; Carl S.; Lehmann E.; Lura P.

    2013-01-01

    Neutron radiography was applied to investigate the water distribution in mortar samples heated from one side to 600 °C. In mortar, aggregates and anhydrous cement are almost transparent to neutrons, while hydration products and water-filled capillary pores bear the largest attenuation. The evolution of the moisture profile shows a sharp dehydration front and accumulation of water due to condensation of water vapor behind this front.

  7. Neutron radiography of heated high-performance mortar

    Directory of Open Access Journals (Sweden)

    Weber B.

    2013-09-01

    Full Text Available Neutron radiography was applied to investigate the water distribution in mortar samples heated from one side to 600 °C. In mortar, aggregates and anhydrous cement are almost transparent to neutrons, while hydration products and water-filled capillary pores bear the largest attenuation. The evolution of the moisture profile shows a sharp dehydration front and accumulation of water due to condensation of water vapor behind this front.

  8. The Mortar Element Method with Lagrange Multipliers for Stokes Problem

    Institute of Scientific and Technical Information of China (English)

    Yaqin Jiang

    2007-01-01

    In this paper, we propose a mortar element method with Lagrange multiplier for incompressible Stokes problem, i.e., the matching constraints of velocity on mortar edges are expressed in terms of Lagrange multipliers. We also present P1 nonconforming element attached to the subdomains. By proving inf-sup condition, we derive optimal error estimates for velocity and pressure. Moreover, we obtain satisfactory approximation for normal derivatives of the velocity across the interfaces.

  9. Estimation of masonry mortars strength during stone buildings investigation (rus)

    OpenAIRE

    Derkach V.N.; Orlovich R.B.

    2011-01-01

    In this article the analysis of estimation methods of the masonry mortars strength applied in Russia and other countries during stone buildings and constructions investigation was carried out. Advantages and disadvantages of these methods are considered.The new technique of masonry mortars strength estimation is offered. It is based on trials of bored from a masonry body cylindrical samples. It is pointed, that this method is the most universal and informative from all methods considered in t...

  10. Mortar for covering structural elements, with high acustic performance levels

    OpenAIRE

    Sanchez de Rojas, M.I.; Olaya Adán, Manuel; Frías Rojas, Moisés; Olmeda, J.; Frutos Vázquez, Borja; Rivera Lozano, Julián; Esteban, J. Luis

    2011-01-01

    [EN] The incorporation of a covering mortar based on cement and granulated coke with particle diameters between 1 and 6 mm, into structural elements such as a brickwork extrados, gives a dual effect of enhanced acoustic insulation. This effect is due to the increase in the mass by the spraying of the mortar and to acoustic absorption as a consequence of the porous network of the material applied. The acoustic performance levels achieved exceed those of the same configuration as a double wall ...

  11. Strength and Drying Shrinkage of Alkali-Activated Slag Paste and Mortar

    Directory of Open Access Journals (Sweden)

    Mao-chieh Chi

    2012-01-01

    Full Text Available The aim of this study is to investigate the strengths and drying shrinkage of alkali-activated slag paste and mortar. Compressive strength, tensile strength, and drying shrinkage of alkali-activated slag paste and mortar were measured with various liquid/slag ratios, sand/slag ratios, curing ages, and curing temperatures. Experimental results show that the higher compressive strength and tensile strength have been observed in the higher curing temperature. At the age of 56 days, AAS mortars show higher compressive strength than Portland cement mortars and AAS mortars with liquid/slag ratio of 0.54 have the highest tensile strength in all AAS mortars. In addition, AAS pastes of the drying shrinkage are higher than AAS mortars. Meanwhile, higher drying shrinkage was observed in AAS mortars than that observed comparable Portland cement mortars.

  12. Experimental studies on the inventory of cement-derived colloids in the pore water of a cementitious backfill material

    International Nuclear Information System (INIS)

    The potential role of near-field colloids for the colloid-facilitated migration of radionuclides has stimulated investigations concerning the generation and presence of colloids in the near-field of a repository for low- and intermediate level waste (L/ILW). The highly gas permeable mortar (Nagra designation: mortar M1) is currently favoured as backfill material for the engineered barrier of the planned Swiss L/ILW repository. The cementitious backfill is considered to be a chemical environment with some potential for colloid generation. In a series of batch-style laboratory experiments the physico-chemical processes controlling the inventory of colloids in cement pore water of the backfill were assessed for chemical conditions prevailing in the initial stage of the cement degradation. In these experiments, backfill mortar M1 or quartz, respectively, which may be used as aggregate material for the backfill, were immersed in artificial cement pore water (a NaOH/KOH rich cement fluid). Colloid concentrations in the cement pore water were recorded as a function of time for different experimental settings. The results indicate that a colloid-colloid interaction process (coagulation) controlled the colloid inventory. The mass concentration of dispersed colloids was found to be typically lower than 0.02 ppm in undisturbed batch systems. An upper-bound value was estimated to be 0.1 ppm taking into account uncertainties on the measurements. To assess the potential for colloid generation in a dynamic system, colloid concentrations were determined in the pore water of a column filled with backfill mortar. The chemical conditions established in the mortar column corresponded to conditions observed in the second stage of the cement degradation (a Ca(OH)2- controlled cement system). In this dynamic system, the upper-bound value for the colloid mass concentration was estimated to be 0.1 ppm. Implications for radionuclide mobility were deduced taking into account the experimental

  13. Experimental studies on the inventory of cement-derived colloids in the pore water of a cementitious backfill material

    Energy Technology Data Exchange (ETDEWEB)

    Wieland, E

    2001-06-01

    The potential role of near-field colloids for the colloid-facilitated migration of radionuclides has stimulated investigations concerning the generation and presence of colloids in the near-field of a repository for low- and intermediate level waste (L/ILW). The highly gas permeable mortar (Nagra designation: mortar M1) is currently favoured as backfill material for the engineered barrier of the planned Swiss L/ILW repository. The cementitious backfill is considered to be a chemical environment with some potential for colloid generation. In a series of batch-style laboratory experiments the physico-chemical processes controlling the inventory of colloids in cement pore water of the backfill were assessed for chemical conditions prevailing in the initial stage of the cement degradation. In these experiments, backfill mortar M1 or quartz, respectively, which may be used as aggregate material for the backfill, were immersed in artificial cement pore water (a NaOH/KOH rich cement fluid). Colloid concentrations in the cement pore water were recorded as a function of time for different experimental settings. The results indicate that a colloid-colloid interaction process (coagulation) controlled the colloid inventory. The mass concentration of dispersed colloids was found to be typically lower than 0.02 ppm in undisturbed batch systems. An upper-bound value was estimated to be 0.1 ppm taking into account uncertainties on the measurements. To assess the potential for colloid generation in a dynamic system, colloid concentrations were determined in the pore water of a column filled with backfill mortar. The chemical conditions established in the mortar column corresponded to conditions observed in the second stage of the cement degradation (a Ca(OH){sub 2{sup -}} controlled cement system). In this dynamic system, the upper-bound value for the colloid mass concentration was estimated to be 0.1 ppm. Implications for radionuclide mobility were deduced taking into account the

  14. Applicability of Carbonated Electric Arc Furnace Slag to Mortar

    Science.gov (United States)

    Yokoyama, S.; Arisawa, R.; Hisyamudin, M. N. N.; Murakami, K.; Maegawa, A.; Izaki, M.

    2012-03-01

    Authors have been studying the absorption of CO2 in the steelmaking slag. In this study, an application of the electric arc furnace slag after the carbonation to admixture of mortar was investigated with the JIS (A6206-1997) method for ground granulated blast-furnace slag for concrete. The percent flows for the test mortar were smaller than that for the standard mortar. The percent flow of the carbonated slag whose average particle size of more than approximately 4 μm increased with an increase in the average size of the particles. Because the compressive strengths of the test mortar cured for 91 days were almost the same as those cured 28 days, the slag after the carbonation was thought not to have self-hardening property for a medium and long term. The compressive strength for the test mortar was almost unchanged within a range of approximately 2 to 7 μm of the average particle size, and it in this range was highest. The activity indexes for the test mortar prepared with the slag after the carbonation ranged from approximately 40 to 60 %.

  15. High performance superplasticized silica fume mortars for ferrocement works

    Directory of Open Access Journals (Sweden)

    Rathish Kumar P.

    2010-01-01

    Full Text Available Ferrocement works demand cement mortars of good workability and high strength. Reduction in water-cement ratio combined with a refined pore structure increases the compressive strength in addition to the enhancement of durability characteristics, but the workability decreases. Workability becomes important, as the mortar has to easily penetrate between the layers of the mesh wires. A reasonably workable high strength cement mortar can be obtained by using a high cement content coupled with the use of superplasticizers. These were also found to retain the cohesiveness and check undesirable bleeding and segregation. An experimental program was conducted to study the functional efficacy of an SNF condensate used as a water reducing superplasticizer. The compressive strength and flow characteristics of the mortars were determined to decide their suitability for ferrocement works. The parameters included the mix proportions, the grade of cement, age of curing and the dosage of superplasticizer. It was concluded from the study that the addition of an optimum dosage of superplasticizer improved the workability and strength characteristics of silica fume mortars. There was a late gain in the compressive strength of silica fume mortars.

  16. Applicability of Carbonated Electric Arc Furnace Slag to Mortar

    International Nuclear Information System (INIS)

    Authors have been studying the absorption of CO2 in the steelmaking slag. In this study, an application of the electric arc furnace slag after the carbonation to admixture of mortar was investigated with the JIS (A6206-1997) method for ground granulated blast-furnace slag for concrete. The percent flows for the test mortar were smaller than that for the standard mortar. The percent flow of the carbonated slag whose average particle size of more than approximately 4 μm increased with an increase in the average size of the particles. Because the compressive strengths of the test mortar cured for 91 days were almost the same as those cured 28 days, the slag after the carbonation was thought not to have self-hardening property for a medium and long term. The compressive strength for the test mortar was almost unchanged within a range of approximately 2 to 7 μm of the average particle size, and it in this range was highest. The activity indexes for the test mortar prepared with the slag after the carbonation ranged from approximately 40 to 60%.

  17. Temperature effect on the poro-mechanical or hydraulic behaviour of a carbonated rock and a mortar: experimental studies; Influence de la temperature sur le comportement poromecanique ou hydraulique d'une roche carbonatee et d'un mortier: etudes experimentales

    Energy Technology Data Exchange (ETDEWEB)

    Lion, M

    2004-07-15

    The main objective of this study is to evaluate the temperature effect on the hydraulic and poro-mechanical behaviour of a limestone. Many experimental tests (porosity and permeability measurements, uniaxial and hydrostatic compressions tests) were carried out in order to study the thermal treatments effect and so the thermal microcracking effect on rock behaviour. Moreover, an experimental device for permeability measurements under high temperatures (until 200 C) was realized. This experimental device permitted to study the permeability variation of the limestone under thermal stresses. Finally, the behaviour of cementitious materials was studied; the temperature effect on the permeability of a mortar was examined. (author)

  18. Electrodialytically treated MSWI APC residue as substitute for cement in mortar

    DEFF Research Database (Denmark)

    Kirkelund, Gunvor Marie; Geiker, Mette Rica; Jensen, Pernille Erland

    2014-01-01

    /or electrodialytic remediation, were used in Portland cement mortar. Mortar bars with 15 % weight replacement of cement by APC residues showed compressive strengths up to 40 MPa after 28/32 days. Heavy metal and salt leaching from both crushed and monolithic mortars with APC residues was generally similar and...... comparable to both the reference mortar and mortar with coal fly ash. These results indicate that electrodialytic remediation could be used a pre-treatment method for MSWI APC residues prior to reuse in mortar....

  19. Cementitious Barriers Partnership FY2013 End-Year Report

    Energy Technology Data Exchange (ETDEWEB)

    Flach, G. P. [Savannah River Site (SRS), Aiken, SC (United States); Langton, C. A. [Savannah River Site (SRS), Aiken, SC (United States); Burns, H. H. [Savannah River Site (SRS), Aiken, SC (United States); Smith, F. G. [Savannah River Site (SRS), Aiken, SC (United States); Kosson, D. S. [Vanderbilt University, School of Engineering, Nashville, TN (United States); Brown, K. G. [Vanderbilt University, School of Engineering, Nashville, TN (United States); Samson, E. [SIMCO Technologies, Inc., Quebec (Canada); Meeussen, J. C.L. [Nuclear Research and Consultancy Group (NRG), Petten (The Netherlands); van der Sloot, H. A. [Hans van der Sloot Consultancy, Langedijk (The Netherlands); Garboczi, E. J. [Materials & Construction Research Division, National Institute of Standards and Technology, Gaithersburg, MD (United States)

    2013-11-01

    In FY2013, the Cementitious Barriers Partnership (CBP) demonstrated continued tangible progress toward fulfilling the objective of developing a set of software tools to improve understanding and prediction of the long-term structural, hydraulic and chemical performance of cementitious barriers used in nuclear applications. In November 2012, the CBP released “Version 1.0” of the CBP Software Toolbox, a suite of software for simulating reactive transport in cementitious materials and important degradation phenomena. In addition, the CBP completed development of new software for the “Version 2.0” Toolbox to be released in early FY2014 and demonstrated use of the Version 1.0 Toolbox on DOE applications. The current primary software components in both Versions 1.0 and 2.0 are LeachXS/ORCHESTRA, STADIUM, and a GoldSim interface for probabilistic analysis of selected degradation scenarios. The CBP Software Toolbox Version 1.0 supports analysis of external sulfate attack (including damage mechanics), carbonation, and primary constituent leaching. Version 2.0 includes the additional analysis of chloride attack and dual regime flow and contaminant migration in fractured and non-fractured cementitious material. The LeachXS component embodies an extensive material property measurements database along with chemical speciation and reactive mass transport simulation cases with emphasis on leaching of major, trace and radionuclide constituents from cementitious materials used in DOE facilities, such as Saltstone (Savannah River) and Cast Stone (Hanford), tank closure grouts, and barrier concretes. STADIUM focuses on the physical and structural service life of materials and components based on chemical speciation and reactive mass transport of major cement constituents and aggressive species (e.g., chloride, sulfate, etc.). THAMES is a planned future CBP Toolbox component focused on simulation of the microstructure of cementitious materials and calculation of resultant

  20. Monitoring of self-healing phenomena towards enhanced sustainability of historic mortars

    Science.gov (United States)

    Amenta, M.; Karatasios, I.; Maravelaki, P.; Kilikoglou, V.

    2016-05-01

    Mortars are known for their ability to heal their defects in an autogenic way. This phenomenon is expressed by the filling of microcracks by secondary products, restoring or enhancing the material's performance. Parameterization of self-healing phenomenon could be a key factor for the enhanced sustainability of these materials in terms of reduced repair cost and consumption of natural raw materials and thus reduced environmental fingerprint. The fact that this phenomenon takes place autogenously suggests that the material can self-repair its defects, without external intervention, thus leading to a prolonged life cycle. In the present study, the autogenic self-healing phenomenon was studied in natural hydraulic lime mortars, considering aspects of curing time before initial cracking, duration and conditions of the healing period. Furthermore, strength recovery due to autogenic self-healing was measured under high humidity conditions, and thermo-gravimetric analysis (DTA/TG) was performed in all specimens in order to quantitatively assess the available unreacted components in the binder at all ages. Regarding the microstructure of the healing phases, the main products formed during healing consist of calcite and various C-S-H/C-A-H phases. Depending on the parameters mentioned above, there is a wide diversity in the intensity, typology and topography of the secondary phases inside the cracks. The main differences discussed were observed between specimens cracked at very early age and those damaged after 30 days of curing. Similarly, the mechanical properties of the crack-healed specimens were associated with the above findings and especially with the available each-time amount of lime, determined by thermo-gravimetric analysis.

  1. Pulse Velocity Measurements in Fly Ash Blended Cementitious Systems Containing 43 Grade Cement

    OpenAIRE

    V.M. Sounthararajan; Mr. A. Sivakumar

    2013-01-01

    Investigations on the different supplementary cementitious materials based on the hardening properties and the optimized dosage in cementitious systems find the right choice of pozzolanic material. It is essential to combine various additive/admixtures in concrete in proper proportions to maximize the benefits resulting in cost savings in construction. In the recent years, production technology and composition of hydraulic cements affect the setting and early age behavior of cementitious mate...

  2. Influence of Cementitious Materials and Aggregates Content on Compressive Strength of Palm Kernel Shell Concrete

    OpenAIRE

    U.J. Alengaram; Jumaat, M. Z.; H. Mahmud

    2008-01-01

    This study reports the effect of cementitious materials, fine and coarse aggregates content on workability and compressive strength of palm kernel shell concrete. Palm kernel shells a by product of the production of palm oil, were used as lightweight aggregates. The following cementitious materials were added: 10% silica fume as additional cementitious material and 5% fly ash as cement replacement on weight of cement. The influence of varying fine aggregate and palm kernel shell content...

  3. Talc as raw material for cementitious products formulation

    Directory of Open Access Journals (Sweden)

    C.J. Ngally Sabouang

    2014-09-01

    Full Text Available This study reports the characterization of a talc from Cameroon as a possible source material for cement formulation. To that end, the talc sample was characterized and mixed with a solution of sodium polyphosphate to formulate the cementitious products. Addition of magnesia (MgO was done to analyze the effect of available MgO on the products. Fourier transform infrared, X-rays diffraction, linear shrinkage, compressive strength and scanning electron microscopy were used to analyze the products. The compressive strength increased with addition of MgO and the linear shrinkage decreased. All the analyses indicate that talc is a raw material of interest in cementitious products formulation; however, the inclusion of the MgO is a key factor for a better performance of the products.

  4. Progress in Research on Carbon Nanotubes Reinforced Cementitious Composites

    Directory of Open Access Journals (Sweden)

    Qinghua Li

    2015-01-01

    Full Text Available As one-dimensional (1D nanofiber, carbon nanotubes (CNTs have been widely used to improve the performance of nanocomposites due to their high strength, small dimensions, and remarkable physical properties. Progress in the field of CNTs presents a potential opportunity to enhance cementitious composites at the nanoscale. In this review, current research activities and key advances on multiwalled carbon nanotubes (MWCNTs reinforced cementitious composites are summarized, including the effect of MWCNTs on modulus of elasticity, porosity, fracture, and mechanical and microstructure properties of cement-based composites. The issues about the improvement mechanisms, MWCNTs dispersion methods, and the major factors affecting the mechanical properties of composites are discussed. In addition, large-scale production methods of MWCNTs and the effects of CNTs on environment and health are also summarized.

  5. Hybrid fiber reinforcement and crack formation in Cementitious Composite Materials

    DEFF Research Database (Denmark)

    Pereira, E.B.; Fischer, Gregor; Barros, J.A.O.

    2011-01-01

    The use of different types of fibers simultaneously for reinforcing cementitious matrices is motivated by the concept of a multi-scale nature of the crack propagation process. Fibers with different geometrical and mechanical properties are used to bridge cracks of different sizes from the micro- to...... the macroscale. In this study, the performance of different fiber reinforced cementitious composites is assessed in terms of their tensile stress-crack opening behavior. The results obtained from this investigation allow a direct quantitative comparison of the behavior obtained from the different...... fiber reinforcement systems. The research described in this paper shows that the multi-scale conception of cracking and the use of hybrid fiber reinforcements do not necessarily result in an improved tensile behavior of the composite. Particular material design requirements may nevertheless justify the...

  6. Hybrid fiber reinforcement and crack formation in Cementitious Composite Materials

    DEFF Research Database (Denmark)

    Pereira, E.B.; Fischer, Gregor; Barros, J.A.O.

    2011-01-01

    the macroscale. In this study, the performance of different fiber reinforced cementitious composites is assessed in terms of their tensile stress-crack opening behavior. The results obtained from this investigation allow a direct quantitative comparison of the behavior obtained from the different......The use of different types of fibers simultaneously for reinforcing cementitious matrices is motivated by the concept of a multi-scale nature of the crack propagation process. Fibers with different geometrical and mechanical properties are used to bridge cracks of different sizes from the micro- to...... fiber reinforcement systems. The research described in this paper shows that the multi-scale conception of cracking and the use of hybrid fiber reinforcements do not necessarily result in an improved tensile behavior of the composite. Particular material design requirements may nevertheless justify the...

  7. Leaching from cementitious waste forms in belowground vaults

    International Nuclear Information System (INIS)

    Solidification and/or stabilization with cementitious materials prior to burial is one option for disposal of liquid hazardous and radioactive wastes. A common design for disposal of cementitious waste forms is to pour the material into large belowground vaults. The leaching performance of partially degraded monolithic vaults is examined quantitatively for facilities located in humid to semiarid climates. Development of perched water on the vault roof leading to fracture flow through the structure is predicted for a wide range of climate and design conditions. Leaching controlled by diffusion in matrix blocks out to fractures is examined parametrically in relation to water flux rate and crack spacing. Depending upon the parameters examined, release rate may be controlled by water flux rate or diffusion. Under some circumstances, contaminant release rates and exit concentrations are predicted to be inversely related. In this situation, minimization of release does not result in the lowest predicted groundwater concentrations below the vault

  8. A multiscale mortar multipoint flux mixed finite element method

    KAUST Repository

    Wheeler, Mary Fanett

    2012-02-03

    In this paper, we develop a multiscale mortar multipoint flux mixed finite element method for second order elliptic problems. The equations in the coarse elements (or subdomains) are discretized on a fine grid scale by a multipoint flux mixed finite element method that reduces to cell-centered finite differences on irregular grids. The subdomain grids do not have to match across the interfaces. Continuity of flux between coarse elements is imposed via a mortar finite element space on a coarse grid scale. With an appropriate choice of polynomial degree of the mortar space, we derive optimal order convergence on the fine scale for both the multiscale pressure and velocity, as well as the coarse scale mortar pressure. Some superconvergence results are also derived. The algebraic system is reduced via a non-overlapping domain decomposition to a coarse scale mortar interface problem that is solved using a multiscale flux basis. Numerical experiments are presented to confirm the theory and illustrate the efficiency and flexibility of the method. © EDP Sciences, SMAI, 2012.

  9. Use of rubble from building demolition in mortars.

    Science.gov (United States)

    Corinaldesi, V; Giuggiolini, M; Moriconi, G

    2002-01-01

    Because of increasing waste production and public concerns about the environment, it is desirable to recycle materials from building demolition. If suitably selected, ground, cleaned and sieved in appropriate industrial crushing plants, these materials can be profitably used in concrete. Nevertheless, the presence of masonry instead of concrete rubble is particularly detrimental to the mechanical performance and durability of recycled-aggregate concrete and the same negative effect is detectable when natural sand is replaced by fine recycled aggregate fraction. An alternative use of both masonry rubble and fine recycled material fraction could be in mortars. These could contain either recycled instead of natural sand or powder obtained by bricks crushing as partial cement substitution. In particular, attention is focused on the modification that takes place when either polypropylene or stainless steel fibers are added to these mortars. Polypropylene fibers are added in order to reduce shrinkage of mortars, stainless steel fibers for improving their flexural strength. The combined use of polypropylene fibers and fine recycled material from building demolition could allow the preparation of mortars showing good performance, in particular when coupled with bricks. Furthermore, the combined use of stainless steel fibers and mortars containing brick powder seems to be an effective way to guarantee a high flexural strength. PMID:12423051

  10. NMR relaxometry study of plaster mortar with polymer additives

    Energy Technology Data Exchange (ETDEWEB)

    Jumate, E.; Manea, D. [Technical University of Cluj-Napoca, Faculty of Civil Engineering. 15 C Daicoviciu Str., 400020, Cluj-Napoca (Romania); Moldovan, D.; Fechete, R. [Technical University of Cluj-Napoca, Department of Physics and Chemistry, 25 G. Baritiu Str., 400027, Cluj-Napoca (Romania)

    2013-11-13

    The cement mixed with water forms a plastic paste or slurry which stiffness in time and finally hardens into a resistant stone. The addition of sand aggregates, polymers (Walocel) and/or calcium carbonate will modify dramatically the final mortar mechanic and thermal properties. The hydration processes can be observed using the 1D NMR measurements of transverse T{sub 2} relaxation times distributions analysed by a Laplace inversion algorithm. These distributions were obtained for mortar pasta measured at 2 hours after preparation then at 3, 7 and 28 days after preparation. Multiple components are identified in the T{sub 2} distributions. These can be associated with the proton bounded chemical or physical to the mortar minerals characterized by a short T{sub 2} relaxation time and to water protons in pores with three different pore sizes as observed from SEM images. The evaporation process is faster in the first hours after preparation, while the mortar hydration (bonding of water molecules to mortar minerals) can be still observed after days or months from preparation. Finally, the mechanic resistance was correlated with the transverse T{sub 2} relaxation rates corresponding to the bound water.

  11. Electrochemical migration technique to accelerate ageing of cementitious materials

    OpenAIRE

    Abbas Z.; Tang L; Babaahmadi A.

    2013-01-01

    Durability assessment of concrete structures for constructions in nuclear waste repositories requires long term service life predictions. As deposition of low and intermediate level radioactive waste (LILW) takes up to 100 000 years, it is necessary to analyze the service life of cementitious materials in this time perspective. Using acceleration methods producing aged specimens would decrease the need of extrapolating short term data sets. Laboratory methods are therefore, needed for acceler...

  12. Corrosion of cementitious materials under geological disposal conditions

    International Nuclear Information System (INIS)

    The long-term behavior of cementitious materials in high saline brines has been investigated by means of a time accelerating leaching experiment and by the geochemical modeling. The investigated materials, salt cement and oxychloride cement, were leached with a saturated NaCl solution and an 1P21 solution, likely to occur in salt and potash mines, used in Germany as repositories for radioactive and hazardous chemical wastes. The employed leaching experiment was developed at GRS specifically for boundary conditions of underground repositories. The experimentally observed reaction path was modeled using the computer code EQ3/6 and compared with results of a full-scale experiment in the Asse salt mine. A good agreement between experimental data and the modelling results was obtained. The employed experimental and modelling tools have proved to be suitable for the evaluation of the long-term stability of cementitious materials in repositories in salt formations. Considering the good agreement between the long lasting full-scale in-situ experiment and the time accelerating laboratory scale cascade experiments we conclude, that it is possible to predict the chemical behavior of cementitious materials in salt solutions. The cascade experiment is a fast method, that enables the prediction of the chemical changes in solution during the cement corrosion processes. For the investigated materials in contact to brines a good agreement between the experimental data and the modeling results was obtained. The existing thermodynamic database for the geochemical modeling however is still incomplete. Solubility data and dissolution models for CSH phases are incomplete or missing. The Pitzer coefficients of Si and Al still need to be determined more accurately. However the present state of the geochemical modeling with the existing database allows a valuable insight into the processes taking place along the reaction path in the extremely complex system. The employed experimental and

  13. Effect of Limestone Powder on Microstructure of Ternary Cementitious System

    OpenAIRE

    Zhang, Y.; Ye, G.

    2012-01-01

    The pressure to reach sustainability favours the development of ternary composite cement. The synergistic effect on mechanical behaviour at 28 days between limestone powder (LP) and pozzolanic additives, i.e. fly ash (FA) and blast furnace slag (BFS), has been documented. In order to better understand the synergistic effect, this article investigated the effect of LP on the microstructure of PC-FA and PC-BFS cementitious system. The mineralogy and pore structure were determined after 28 days ...

  14. Atmospheric carbonation of low portlandite content cementitious materials

    OpenAIRE

    Morandeau, Antoine

    2013-01-01

    Reaction of gaseous atmospheric CO2 with calcium-bearing phases in concrete infrastructure components is known to cause a lowering of alkalinity, leading to depassivation and corrosion of rebars. Carbonation mechanism is quite well understood from a physico-chemical point of view, especially in the case of materials made of OPC. Nonetheless the impact of supplementary cementitious materials (SCM), such as fly-ash, on carbonation is still an active research field. The pozzolanic reaction betwe...

  15. Meso-mechanical analysis of steel fiber reinforced cementitious composites

    OpenAIRE

    Caggiano, Antonio

    2013-01-01

    2010 - 2011 The mechanical behavior of cement-based materials is greatly affected by crack propagation under general stress states. The presence of one or more dominant cracks in structural members modifies its response, possibly leading to brittle failure modes. The random dispersion of short steel fibers in cement materials is a new methodology used for enhancing the response in the post-cracking regime. The behavior of Fiber-Reinforced Cementitious Composite (FRCC), compared...

  16. Thermodynamics of Autogenous Self-healing in Cementitious Materials

    OpenAIRE

    Huang, H

    2014-01-01

    Concrete is a brittle composite cementitious material that easily fractures under tensile loading. Microcracks can appear throughout the concrete prior to application of any load because of temperature-induced strain and autogenous and drying shrinkage. There is no doubt that these cracks provide preferential access for aggressive agents to penetrate into the concrete, probably causing corrosion of reinforcement steel and degradation of concrete. As a result, the service life of reinforced co...

  17. Computer Modeling of Leaching of Heavy Metal from Cementitious Waste

    OpenAIRE

    Peng Hu; Wei Dai

    2013-01-01

    Thermodynamic equilibrium model was used to simulate the results of leaching heavy metal from cementitious wastes. Modeling results of the leached major element concentrations for samples agreed well with the leaching test using the set of pure minerals and solid solutions present in the database. The model revealed Pb and Cd were predominantly incorporated within the calcium silicate hydrate matrix while a greater portion of Cd exist as discrete particles in the cement pores. Precipitation w...

  18. Mechanical properties of structures 3D printed with cementitious powders

    OpenAIRE

    Feng, Peng; Meng, Xinmiao; Chen, Jian Fei; Ye, Lieping

    2015-01-01

    The three dimensional (3D) printing technology has undergone rapid development in the last few years and it is now possible to print engineering structures. This paper presents a study of the mechanical behavior of 3D printed structures using cementitious powder. Microscopic observation reveals that the 3D printed products have a layered orthotropic microstructure, in which each layer consists of parallel strips. Compression and flexural tests were conducted to determine the mechanical proper...

  19. A Plastic Damage Mechanics Model for Engineered Cementitious Composites

    DEFF Research Database (Denmark)

    Dick-Nielsen, Lars; Stang, Henrik; Poulsen, Peter Noe;

    2007-01-01

    This paper discusses the establishment of a plasticity-based damage mechanics model for Engineered Cementitious Composites (ECC). The present model differs from existing models by combining a matrix and fiber description in order to describe the behavior of the ECC material. The model provides...... information about crack opening and spacing, which makes it possible to assess the condition of a structure in the serviceability state. A simulation of a four point bending beam is performed to demonstrate the capability of the model....

  20. Shape optimization of small span textile reinforced cementitious composite shells

    OpenAIRE

    TYSMANS, Tine; ADRIAENSSENS, Sigrid; Wastiels, Jan

    2009-01-01

    p. 1755-1766 The property of concrete to be poured into any shape and harden at ambient temperatures makes it the most widely-used material for shells. Using this traditionally brittle material in shells restricts their forms to mostly compression shapes. Often steel reinforcement is still necessary to carry tensile forces occurring under different load combinations and to limit crack formation. A new composite material, textile reinforced cementitious composite (TRC), eliminates this rest...

  1. Rheology and Reactivity of Cementitious Binders with Plasticizers

    OpenAIRE

    Vikan, Hedda Vestøl

    2005-01-01

    The rheological behaviour of cementitious pastes has been studied by various means. Six different cements have been studied in main parts of the work and all of them have been characterized according to the Rietveld method in order to determine the exact content of minerals. Easily soluble alkalis were measured by plasma-emission- spectroscopy of the fluid filtered from paste. Three types of plasticizers namely naphthalene sulfonate formaldehyde condensate (SNF), lignosulphonate and polyacryl...

  2. Electrochemical migration technique to accelerate ageing of cementitious materials

    International Nuclear Information System (INIS)

    Durability assessment of concrete structures for constructions in nuclear waste repositories requires long term service life predictions. As deposition of low and intermediate level radioactive waste (LILW) takes up to 100 000 years, it is necessary to analyze the service life of cementitious materials in this time perspective. Using acceleration methods producing aged specimens would decrease the need of extrapolating short term data sets. Laboratory methods are therefore, needed for accelerating the ageing process without making any influencing distortion in the properties of the materials. This paper presents an electro-chemical migration method to increase the rate of calcium leaching from cementitious specimens. This method is developed based on the fact that major long term deterioration process of hardened cement paste in concrete structures for deposition of LILW is due to slow diffusion of calcium ions. In this method the cementitious specimen is placed in an electrochemical cell as a porous path way through which ions can migrate at a rate far higher than diffusion process. The electrical field is applied to the cell in a way to accelerate the ion migration without making destructions in the specimen's micro and macroscopic properties. The anolyte and catholyte solutions are designed favoring dissolution of calcium hydroxide and compensating for the leached calcium ions with another ion like lithium. (authors)

  3. Electrochemical migration technique to accelerate ageing of cementitious materials

    Science.gov (United States)

    Babaahmadi, A.; Tang, L.; Abbas, Z.

    2013-07-01

    Durability assessment of concrete structures for constructions in nuclear waste repositories requires long term service life predictions. As deposition of low and intermediate level radioactive waste (LILW) takes up to 100 000 years, it is necessary to analyze the service life of cementitious materials in this time perspective. Using acceleration methods producing aged specimens would decrease the need of extrapolating short term data sets. Laboratory methods are therefore, needed for accelerating the ageing process without making any influencing distortion in the properties of the materials. This paper presents an electro-chemical migration method to increase the rate of calcium leaching from cementitious specimens. This method is developed based on the fact that major long term deterioration process of hardened cement paste in concrete structures for deposition of LILW is due to slow diffusion of calcium ions. In this method the cementitious specimen is placed in an electrochemical cell as a porous path way through which ions can migrate at a rate far higher than diffusion process. The electrical field is applied to the cell in a way to accelerate the ion migration without making destructions in the specimen's micro and macroscopic properties. The anolyte and catholyte solutions are designed favoring dissolution of calcium hydroxide and compensating for the leached calcium ions with another ion like lithium.

  4. Electrochemical migration technique to accelerate ageing of cementitious materials

    Directory of Open Access Journals (Sweden)

    Abbas Z.

    2013-07-01

    Full Text Available Durability assessment of concrete structures for constructions in nuclear waste repositories requires long term service life predictions. As deposition of low and intermediate level radioactive waste (LILW takes up to 100 000 years, it is necessary to analyze the service life of cementitious materials in this time perspective. Using acceleration methods producing aged specimens would decrease the need of extrapolating short term data sets. Laboratory methods are therefore, needed for accelerating the ageing process without making any influencing distortion in the properties of the materials. This paper presents an electro-chemical migration method to increase the rate of calcium leaching from cementitious specimens. This method is developed based on the fact that major long term deterioration process of hardened cement paste in concrete structures for deposition of LILW is due to slow diffusion of calcium ions. In this method the cementitious specimen is placed in an electrochemical cell as a porous path way through which ions can migrate at a rate far higher than diffusion process. The electrical field is applied to the cell in a way to accelerate the ion migration without making destructions in the specimen’s micro and macroscopic properties. The anolyte and catholyte solutions are designed favoring dissolution of calcium hydroxide and compensating for the leached calcium ions with another ion like lithium.

  5. Mechanical properties of gangue-containing aluminosilicate based cementitious materials

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    High performance aluminosilicate based cementitious materials were produced using calcined gangue as one of the major raw materials.The gangue was calcined at 500℃.The main constituent was calcined gangue, fly ash and slag, while alkali-silicate solutions were used as the diagenetic agent.The structure of gangue-containing aluminosilicate based cementitious materials was studied by the methods of IR, NMR and SEM.The results show that the mechanical properties are affected by the mass ratio between the gangue, slag and fly ash, the kind of activator and additional salt.For 28-day curing time, the compressive strength of the sample with a mass proportion of 2:1:1 (gangue: slag: fly ash) is 58.9 MPa, while the compressive strength of the sample containing 80wt%gangue can still be up to 52.3 MPa.The larger K+ favors the formation of large silicate oligomers with which Al(OH)4- prefers to bind.Therefore, in Na-K compounding activator solutions more oligomers exist which result in a stronger compressive strength of aluminosilicate-based cementitious materials than in the case of Na-containing activator.The reasons for this were found through IR and NMR analysis.Glauber's salt reduces the 3-day compressive strength of the paste, but increases its 7-day and 28-day compressive strengths.

  6. Self healing phenomena in concretes and masonry mortars: A microscopic study

    NARCIS (Netherlands)

    Nijland, T.G.; Larbi, J.A.; Hees, R.P.J. van; Lubelli, B.A.; Rooij, M.R. de

    2007-01-01

    A microscopic survey of over 1000 of samples of concrete and masonry mortars from structures in the Netherlands shows that, in practice, self healing occurs in historic lime and lime – puzzolana mortars, in contrast to modern cement bound concretes and mortars. Self healing may be effected by the fo

  7. Use of red mud as addition for portland cement mortars

    International Nuclear Information System (INIS)

    The aim of the present research work was to investigate the possibility of adding red mud, an alkaline leaching waste that is obtained from bauxite during the Bayer process for alumina production, in the raw meal of Portland cement mortars. The red mud is classified as dangerous, according to NBR 10004/2004, and world while generation reached over 117 million tons/year. This huge production requires high consuming products to be used as incorporation matrix and we studied the influence of red mud addition on the characteristics of cement mortars and concrete. In this paper the properties of Portland cement mortars incorporating high amounts of red mud was evaluated: pH variation, fresh (setting time, workability or normal consistency and water retention), and hardened state (mechanical strength, capillary water absorption, density and apparent porosity). Results seem promising for red mud additions up to 20 wt%. (author)

  8. Influence of pore structure on compressive strength of cement mortar.

    Science.gov (United States)

    Zhao, Haitao; Xiao, Qi; Huang, Donghui; Zhang, Shiping

    2014-01-01

    This paper describes an experimental investigation into the pore structure of cement mortar using mercury porosimeter. Ordinary Portland cement, manufactured sand, and natural sand were used. The porosity of the manufactured sand mortar is higher than that of natural sand at the same mix proportion; on the contrary, the probable pore size and threshold radius of manufactured sand mortar are finer. Besides, the probable pore size and threshold radius increased with increasing water to cement ratio and sand to cement ratio. In addition, the existing models of pore size distribution of cement-based materials have been reviewed and compared with test results in this paper. Finally, the extended Bhattacharjee model was built to examine the relationship between compressive strength and pore structure. PMID:24757414

  9. Influence of Pore Structure on Compressive Strength of Cement Mortar

    Directory of Open Access Journals (Sweden)

    Haitao Zhao

    2014-01-01

    Full Text Available This paper describes an experimental investigation into the pore structure of cement mortar using mercury porosimeter. Ordinary Portland cement, manufactured sand, and natural sand were used. The porosity of the manufactured sand mortar is higher than that of natural sand at the same mix proportion; on the contrary, the probable pore size and threshold radius of manufactured sand mortar are finer. Besides, the probable pore size and threshold radius increased with increasing water to cement ratio and sand to cement ratio. In addition, the existing models of pore size distribution of cement-based materials have been reviewed and compared with test results in this paper. Finally, the extended Bhattacharjee model was built to examine the relationship between compressive strength and pore structure.

  10. Properties of Cement Mortar with Phosphogpysum under Steam Curing Condition

    Directory of Open Access Journals (Sweden)

    Kyoungju Mun

    2008-01-01

    Full Text Available The purpose of this study is to utilize waste PG as an admixture for concrete products cured by steam. For the study, waste PG was classified into 4 forms (dehydrate, β-hemihydrate, III-anhydrite, and II-anhydrite, which were calcined at various temperatures. Also, various admixtures were prepared with PG, fly-ash (FA, and granulated blast-furnace slag (BFS. The basic properties of cement mortars containing these admixtures were analyzed and examined through X-ray diffraction, scanning electron microscopy, compressive strength, and acid corrosion resistance. According to the results, cement mortars made with III-anhydrite of waste PG and BFS exhibited strength similar to that of cement mortars made with II-anhydrite. Therefore, III-anhydrite PG calcined at lower temperature can be used as a steam curing admixture for concrete second production.

  11. Thermal conductivity of foam mortar; Waermeleitfaehigkeit von Porenbeton

    Energy Technology Data Exchange (ETDEWEB)

    Lippe, K.F.; Schwab, H. [Ytong AG, Entwicklungszentrum Schrobenhausen (Germany)

    1999-07-01

    Foam mortar in its present-day form was developed during the 20s in Sweden. It consists of porosified calcium silicate hydrates. Porosification is achieved by adding aluminium powder. Optimization of the micro and macro structure of foam mortar resulted in a construction material of low apparent density, high consistency and dimension stability as well as low thermal conductivity. Foam mortar has the lowest thermal conductivity of all massive wall construction materials. (orig.) [German] Porenbeton in der heutigen Form wurde in den 20iger Jahren in Schweden entwickelt. Er besteht aus porosierten Calciumsilicathydraten. Die Porosierung erfolgt durch Zusatz von Aluminiumpulver. Durch die Optimierung der Mikro- und Makrostruktur des Porenbetons, ist ein Baustoff mit niedriger Rohdichte, hoher Festigkeit und Dimensionsstabilitaet sowie niedriger Waermeleitfaehigkeit entstanden. Porenbeton ist der wandbildende Massivbaustoff mit der niedrigsten Waermeleitfaehigkeit. (orig.)

  12. Durability of waste glass flax fiber reinforced mortar

    International Nuclear Information System (INIS)

    The main concern for natural fibre reinforced mortar composites is the durability of the fibres in the alkaline environment of cement. The composites may undergo a reduction in strength as a result of weakening of the fibres by a combination of alkali attack and fibre mineralisation. In order to enhance the durability of natural fiber reinforced cement composites several approaches have been studied including fiber impregnation, sealing of the matrix pore system and reduction of matrix alkalinity through the use of pozzolanic materials. In this study waste glass powder was used as a pozzolanic additive to improve the durability performance of flax fiber reinforced mortar (FFRM). The durability of the FFRM was studied by determining the effects of ageing in water and exposure to wetting and drying cycles; on the microstructures and flexural behaviour of the composites. The mortar tests demonstrated that the waste glass powder has significant effect on improving the durability of FFRM.

  13. Estimation of masonry mortars strength during stone buildings investigation (rus

    Directory of Open Access Journals (Sweden)

    Derkach V.N.

    2011-11-01

    Full Text Available In this article the analysis of estimation methods of the masonry mortars strength applied in Russia and other countries during stone buildings and constructions investigation was carried out. Advantages and disadvantages of these methods are considered.The new technique of masonry mortars strength estimation is offered. It is based on trials of bored from a masonry body cylindrical samples. It is pointed, that this method is the most universal and informative from all methods considered in this article. The offered testing procedure allows to gain not only a compression strength, but also a shearing strength along horizontal masonry seams. Results of experimental researches of masonry mortars compression strength executed on various techniques are presented.

  14. Study on basalt fiber parameters affecting fiber-reinforced mortar

    Science.gov (United States)

    Orlov, A. A.; Chernykh, T. N.; Sashina, A. V.; Bogusevich, D. V.

    2015-01-01

    This article considers the effect of different dosages and diameters of basalt fibers on tensile strength increase during bending of fiberboard-reinforced mortar samples. The optimal dosages of fiber, providing maximum strength in bending are revealed. The durability of basalt fiber in an environment of cement, by means of microscopic analysis of samples of fibers and fiberboard-reinforced mortar long-term tests is examined. The article also compares the behavior of basalt fiber in the cement stone environment to a glass one and reveals that the basalt fiber is not subject to destruction.

  15. Ancient mortars from Cape Verde: mineralogical and physical characterization

    Science.gov (United States)

    Rocha, Fernando; Costa, Cristiana; Velosa, Ana; Quintela, Ana; Terroso, Denise; Marques, Vera

    2014-05-01

    Times and locations of different building constructions means different knowledge, habits, different construction methods and materials. The study and safeguarding of the architectural heritage takes nowadays a progressive importance as a vehicle for transmission of cultures and history of nations. The coatings are of great importance in the durability of a building due to the protective role of the masonry. The compatibility between the materials with which they are executed (masonry, mortar and grout settlement) promotes the proper functioning of the wall and a consequent increase in durability. Therefore, it becomes important to study and characterize the mortar coating of buildings to know its characteristics and to use compatible materials in the rehabilitation and maintenance of buildings. This study aims to characterize the chemical, physical, mechanical and mineralogical mortar samples collected in buildings in three islands of Cape Verde, for the conservation, rehabilitation and preservation of them. The collected samples belong to buildings constructed in the end of XIX century and in the beginning of XX century. In order to characterize the mortar samples some tests was made, such as X-Ray Diffraction, X- Ray Fluorescence, acid attack and mechanical strength. The samples were divided into three groups depending on origin; so we have a first group collected on the island of Santiago, the second on the island of Saint Vincent and the third on the island of Santo Antao. The samples are all carbonated, but Santiago samples have a lower carbonates content. In terms of insoluble residue (from the acid attack) it was concluded that the samples have similar value ranging from 9 to 26%. The compressive strength of the mortars have a range between 1.36 and 4.55 MPa, which is related to the presence of more binder in samples with higher resistance. The chemical and mineralogical analyzes showed that these consist of lime mortars (binder), natural pozzolan and

  16. Traditional methods of mortar preparation: the hot lime mix

    OpenAIRE

    Margalha, Goreti; Veiga, Rosário; Santos Silva, António; Brito, Jorge

    2011-01-01

    This paper studies the effect of maturation on mortars prepared according to a traditional method of slaking quicklime mixed with sand and kept wet until used (hot lime mix). Two lime/aggregate weight proportions were considered, a rich one (1:5) and a normal one (1:13). The quicklime was used as pieces of crushed calcined limestone and as micronized quicklime, both from industrial production. The mortars prepared with hot lime were kept wet for periods of 1, 7, 45 and 90 days, before mouldin...

  17. Various mortars for anti-fouling purposes in marine environments

    Energy Technology Data Exchange (ETDEWEB)

    Kanematsu, Hideyuki; Masuda, Tomoka [Department of Materials Science and Engineering, Suzuka National College of Technology, Shiroko-cho, Suzuka, Mie 510-0294 (Japan); Miura, Yoko; Kuroda, Daisuke [Department of General Education, The Company, Suzuka National College of Technology, Shiroko-cho, Suzuka, Mie 510-0294 (Japan); Hirai, Nobumitsu [Department of Chemistry and Biochemistry, Suzuka National College of Technology, Shiroko-cho, Suzuka, Mie 510-0294 (Japan); Yokoyama, Seiji [Department of Mechanical Engineering, Toyohashi University of Technology, 1-1, Hibarigaoka, Tenpaku, Toyohashi, Aichi, 441-8580 (Japan)

    2014-02-20

    The antifouling properties for some mortars with steel making slags were investigated by real marine immersion tests and a unique laboratory acceleration tests with a specially devised biofilm acceleration reactors. Mortars mixed with steel making slags containing abundant iron elements tended to form biofilm and also bifouling. The two kinds of biofilm formation tests were used in this study. Real immersion in marine environments and laboratory test with a specially devised biofilm acceleration reactor. The former evaluated the biofouling characteristics more properly, while the latter did the biofilm formation characteristics more effectively.

  18. Repair formulations for fine-grained stone arte-facts

    Czech Academy of Sciences Publication Activity Database

    Tišlová, R.; Novotná, Adéla

    Praha: Institute of Theoretical and Applied Mechanics ASCR, v. v. i, 2015 - (Náprstek, J.; Fischer, C.), s. 328-329 ISBN 978-80-86246-42-0. ISSN 1805-8248. [ Engineering mechanics 2015 /21./. Svratka (CZ), 11.05.2015-14.05.2015] R&D Projects: GA MK(CZ) DF12P01OVV018 Keywords : repair mortar * biodetritic limestone * mudstone * compatibility Subject RIV: AL - Art, Architecture, Cultural Heritage

  19. Shrinkage behaviour and related corrosion performance of low-pH cementitious materials based on OPC or CAC

    Directory of Open Access Journals (Sweden)

    García-Calvo, J. L.

    2016-03-01

    Full Text Available Prior to using low-pH cementitious materials in underground repositories for high level waste, the characteristics determining their long-term durability must be analysed in depth. In this sense, different shrinkage tests have been made on mortar and concrete specimens using low-pH cement formulations based on ordinary portland cement (OPC or calcium aluminate cement (CAC, with high mineral admixtures contents. They showed similar autogenous shrinkage than samples without mineral admixtures but higher drying shrinkage when materials based on OPC with high silica fume contents were considered. Besides, as the use of reinforced concrete could be required in underground repositories, the susceptibility of reinforcement to corrosion when using low-pH cementitious materials based on OPC was analyzed, considering carbon steel and galvanized steel. In the formers corrosion was detected due to the low pore solution pH but any problem was detected when galvanized reinforcement were used.Previo al empleo de materiales con cementos de bajo pH en almacenamientos geológicos profundos (AGP de residuos radiactivos de alta actividad, características relacionadas con su durabilidad a largo plazo deben ser verificadas. Así, su estabilidad volumétrica se ha analizado en morteros y hormigones de bajo pH basados en OPC o CAC, con elevados contenidos de adiciones minerales. Estos presentaron retracciones autógenas similares a las medidas en materiales convencionales, pero retracciones por secado mayores en los basados en OPC y altos contenidos de humo de sílice. Dado que en zonas de los AGP podría emplearse hormigón armado, también se evaluó la susceptibilidad a la corrosión de aceros al carbono y aceros galvanizados en materiales de bajo pH basados en OPC. Se detectó un inicio temprano de corrosión en los primeros debido al bajo pH presente en el fluido de los poros de estos materiales, sin detectarse problemas al emplear aceros galvanizados.

  20. IVO develops a new repair technique for underwater sites. Viscous doughlike substance underwater cracks

    Energy Technology Data Exchange (ETDEWEB)

    Klingstedt, G.; Leisio, C. [ed.

    1998-07-01

    A viscous sealant is revolutionizing repair of the stone and concrete masonry of underwater dams, bridges and canals. There is now no need for expensive and time-consuming cofferdams, since a diver can extrude quick-setting mortar into underwater structures needing repair. This technique has worked well in recent years in various parts of Finland even in strongly flowing water. IVO experts are now starting to look more beyond the borders of Finland

  1. Concrete retrofitting using CFRP and geopolymer mortars

    OpenAIRE

    E. Vasconcelos; S. Fernandes; Aguiar, J. L. Barroso de; Torgal, Fernando Pacheco

    2011-01-01

    A new development in the repair and strengthening of reinforced concrete systems is the use of carbon fiber reinforced polymers (CFRP) strips bonded to concrete substrate with epoxy resins. It has been reported that epoxy adhesive are extremely sensitive to high temperatures. Some authors conclude that the epoxy temperature should not exceed 70 ºC in order to safeguard the adhesiveness of the epoxy and, thus, the integrity and adequate functioning of CFRP. It is noted that even frequently ...

  2. Flexural strengthening of masonry members using advanced cementitious materials

    OpenAIRE

    Barros, Joaquim A. O.; Esmaeeli, Esmaeel; Manning, Elizabeth; Häßler, D.

    2011-01-01

    Two different cement based fiber reinforced composites for the flexural strengthening of masonry beams under monotonic loading are studied. Steel Fiber Reinforced Self- Compacting Concrete (SFRSCC) with tensile strain-softening behavior, and PVA fiber reinforced cement based mortar (SHCC) with tensile Strain-Hardening were the developed composites. Both composites were applied on the tensile surface of masonry beams and the effectiveness of this technique for the flexural stren...

  3. Self-Healing of Microcracks in Engineered Cementitious Composites (ECC Under a Natural Environment

    Directory of Open Access Journals (Sweden)

    Victor C. Li

    2013-07-01

    Full Text Available This paper builds on previous self-healing engineered cementitious composites (ECC research by allowing ECC to heal outdoors, in the natural environment, under random and sometimes extreme environmental conditions. Development of an ECC material that can heal itself in the natural environment could lower infrastructure maintenance costs and allow for more sustainable development in the future by increasing service life and decreasing the amount of resources and energy needed for repairs. Determining to what extent current ECC materials self-heal in the natural environment is the first step in the development of an ECC that can completely heal itself when exposed to everyday environmental conditions. This study monitored outdoor ECC specimens for one year using resonant frequency (RF and mechanical reloading to determine the rate and extent of self-healing in the natural environment. It was found that the level of RF, stiffness, and first cracking strength recovery increased as the duration of natural environment exposure increased. For specimens that underwent multiple damage cycles, it was found that the level of recovery was highly dependent on the average temperature and amount of precipitation between each damage event. However, RF, stiffness, and first cracking strength recovery data for specimens that underwent multiple loading cycles suggest that self-healing functionality can be maintained under multiple damage events.

  4. Microbiological activities in a shallow-ground repository with cementitious wasteform

    International Nuclear Information System (INIS)

    Cementitious wasteform with immobilised nuclear power plant operational radioactive waste disposed in a near surface testing repository for about 20 years have been analysed for microbiological activities. Clean cultures were selected from the main metabolic groups expected within repository environment e.g. anaerobic de-nitrifying, fermenting, sulphur-reducing, iron-reducing, and oxidizing, thio-bacterium and mushrooms. Microbiological species were identified within cementitious wasteform, in the clayey soil near the wasteform and in the contacting water. The most populated medium was the soil with microbial populations Bacillus, Pseudomonas and Micrococcus, and densities of populations up to 3.6*105 colony/g. Microbial populations of generic type Bacillus, Pseudomonas, Rhodococcus, Alcaligenes, Micrococcus, Mycobacterium, and Arthrobacter were identified within cementitious wasteform. Populations of Arthrobacter, Pseudomonas, Alcaligenes, Rhodococcus, Bacillus and Flavobacterium were identified in the water samples contacting the cementitious wasteform. Microbiological species identified are potential destructors of cementitious wasteform and containers. (authors)

  5. Mortar and concrete based on calcium sulphate binders

    NARCIS (Netherlands)

    Bakker, J.J.F.; Brouwers, H.J.H.

    2006-01-01

    In this study both hemi-hydrate and anhydrite are tested as calcium sulphate binders for structural mortar and concrete. The advantage of using calcium sulphates instead of cement as a binder is the fact that the production of calcium sulphate is more environmental friendly than that of cement. For

  6. Salt resistance of lime-based mortars with linseed oil

    Czech Academy of Sciences Publication Activity Database

    Nunes, Cristiana Lara; Slížková, Zuzana; Janotová, Dana

    Florence : University of Florence, 2013. [AMMC Conference on Ancient and Modern Mortars. 07.02.2013-08.02.2013, Florence] R&D Projects: GA MK(CZ) DF11P01OVV008 Keywords : linseed oil * lime * metakaolin * salt resistance Subject RIV: AL - Art, Architecture, Cultural Heritage

  7. Modeling the thermal characteristics of masonry mortar containing recycled materials

    Science.gov (United States)

    Laney, Morgan Gretchen

    As the building industry in the United States rapidly expands, the reuse of recycled demolition waste aggregates is becoming increasingly more important. Currently, the building industry is the largest consumer of natural resources. The constant use of raw virgin aggregate is resulting in depleting resources, lack of space for landfills, increasing costs, and heightened levels of pollution. The use of these recycled aggregates in building envelopes and the study of thermal properties are becoming a popular area of research in order to improve building energy usage. The construction of Zero Energy Buildings (ZEB) is encouraged by the United States government as a result of the unresolved finite resources and environmental pollution. The focus of this research is on the impact of using recycled demolition waste aggregates on thermal properties, including specific heat capacity and thermal conductivity, in masonry mortar applications. The new forms of aggregate were analyzed for efficiency and practical utilization in construction in seven locations across the United States by embedding the new material into the building envelope of a strip mall mercantile build model from the National Renewable Energy Laboratory (NREL) in the EnergyPlus Building Energy Simulation Program (BESP). It was determined that the recycled aggregate mortar mixtures performed as well as or better than the traditional mortar mix. Opportunities for future research in recycled aggregate mortar mixtures exist in a regional analysis, a regional recycled aggregate cost analysis, and a life cycled cost analysis (LCCA).

  8. The colour potentials of SSA-containing mortar

    DEFF Research Database (Denmark)

    Kappel, Annemette; Ottosen, Lisbeth M.; Kirkelund, Gunvor Marie;

    2015-01-01

    This paper reports an experimental study of aesthetical qualities of mortar containing sewage sludgeash (SSA). SSA is the residue produced at water treatment plants where incineration of the sludge is applied in order to decrease volume and to prevent pathogens from spreading. Today SSA is with a...

  9. Low Carbon Footprint Mortar from Pozzolanic Waste Material

    Directory of Open Access Journals (Sweden)

    Taha Mehmannavaz

    2014-04-01

    Full Text Available Nowadays, Portland cement clinker leads to emission of CO2 into the atmosphere and therefore causes greenhouse effect. Incorporating of Palm Oil Fuel Ash (POFA and Pulverized Fuel Ash (PFA as partial cement replacement materials into mix of low carbon mortar decreases the amount of cement use and reduces high dependence on cements compared to ordinary mortar. The result of this research supported use of the new concept in preparing low carbon mortar for industrial constructions. Strength of low carbon mortar with POFA and PFA replacement in cement was affected and changed by replacing percent finesse, physical and chemical properties and pozzolanic activity of these wastes. Waste material replacement instead of Ordinary Portland Cement (OPC was used in this study. This in turn was useful for promoting better quality of construction and innovative systems in construction industry, especially in Malaysia. This study was surely a step forward to achieving quality products which were affordable, durable and environmentally friendly. Disposing ash contributes to shortage of landfill space in Malaysia. Besides, hazard of ash might be another serious issue for human health. The ash disposal area also might create a new problem, which is the area's sedimentation and erosion.

  10. A nano approach to consolidation of degraded historic lime mortars

    Czech Academy of Sciences Publication Activity Database

    Drdácký, Miloš; Slížková, Zuzana; Ziegenbalg, G.

    2009-01-01

    Roč. 8, č. 2 (2009), s. 13-22. ISSN 1662-5250 R&D Projects: GA ČR(CZ) GA103/06/1609 Institutional research plan: CEZ:AV0Z20710524 Keywords : lime water * calcium hydroxide nanosuspension * lime mortar Subject RIV: AL - Art, Architecture, Cultural Heritage Impact factor: 0.571, year: 2009

  11. Simulation of self-healing of dolomitic lime mortar

    NARCIS (Netherlands)

    Lubelli, B.; Nijland, T.G.; Van Hees, R.P.J.

    2011-01-01

    In the present research a test procedure was set up to reproduce self-healing on lime-based (both pure calcium and magnesium-calcium) mortar specimens in laboratory. After few months testing, during which the specimens were subjected to wet-dry cycles, thin sections of the specimens were prepared an

  12. Simulation of the self-healing of dolomitic lime mortar

    NARCIS (Netherlands)

    Lubelli, B.; Nijland, T.G.; Hees, R.P.J. van

    2012-01-01

    A test procedure was set up to reproduce laboratory self-healing on lime-based (both pure calcium and magnesium-calcium) mortar specimens. After a few months of testing, during which time the specimens were submitted to wet-dry cycles, thin sections of the specimens were prepared and observed using

  13. Nano-materials for consolidation of degraded historic lime mortars

    Czech Academy of Sciences Publication Activity Database

    Drdácký, Miloš; Slížková, Zuzana; Ziegenbalg, G.

    - : -, 2008 - (Baxter, D.; Bay, B.). s. 86-86 ISBN N. [IC4N From nanoparticles and nanomaterial s to nanodevices and nanosystems /1./. 16.06.2008-18.06.2008, Halkidiki] Institutional research plan: CEZ:AV0Z20710524 Keywords : nanomaterial * consolidation * lime mortar Subject RIV: JN - Civil Engineering

  14. Lime-water consolidation effects on poor lime mortars

    Czech Academy of Sciences Publication Activity Database

    Drdácký, Miloš; Slížková, Zuzana

    2012-01-01

    Roč. 43, č. 1 (2012), s. 31-36. ISSN 0044-9466 R&D Projects: GA ČR(CZ) GA103/09/2067 Institutional support: RVO:68378297 Keywords : lime mortars * lime-water consolidation * conservation Subject RIV: JN - Civil Engineering

  15. Non-standard testing of mechanical characteristics of historic mortars

    Czech Academy of Sciences Publication Activity Database

    Drdácký, Miloš

    2011-01-01

    Roč. 5, 4-5 (2011), s. 383-394. ISSN 1558-3058 R&D Projects: GA ČR(CZ) GA103/09/2067 Institutional research plan: CEZ:AV0Z20710524 Keywords : non-standard test specimen * historic mortar * compressive strength Subject RIV: AL - Art, Architecture, Cultural Heritage Impact factor: 0.235, year: 2011

  16. CEMENTITIOUS BARRIERS PARTNERSHIP FY13 MID-YEAR REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Burns, H.; Flach, G.; Langton, C.; KOSSON, D.; BROWN, K.; SAMSON, E.; MEEUSSEN, J.; SLOOT, H.; GARBOCZI, E.

    2013-05-01

    In FY2013, the Cementitious Barriers Partnership (CBP) is continuing in its effort to develop and enhance software tools demonstrating tangible progress toward fulfilling the objective of developing a set of tools to improve understanding and prediction of the long‐term structural, hydraulic and chemical performance of cementitious barriers used in nuclear applications. In FY2012, the CBP released the initial inhouse “Beta‐version” of the CBP Software Toolbox, a suite of software for simulating reactive transport in cementitious materials and important degradation phenomena. The current primary software components are LeachXS/ORCHESTRA, STADIUM, and a GoldSim interface for probabilistic analysis of selected degradation scenarios. THAMES is a planned future CBP Toolbox component (FY13/14) focused on simulation of the microstructure of cementitious materials and calculation of resultant hydraulic and constituent mass transfer parameters needed in modeling. This past November, the CBP Software Toolbox Version 1.0 was released that supports analysis of external sulfate attack (including damage mechanics), carbonation, and primary constituent leaching. The LeachXS component embodies an extensive material property measurements database along with chemical speciation and reactive mass transport simulation cases with emphasis on leaching of major, trace and radionuclide constituents from cementitious materials used in DOE facilities, such as Saltstone (Savannah River) and Cast Stone (Hanford), tank closure grouts, and barrier concretes. STADIUM focuses on the physical and structural service life of materials and components based on chemical speciation and reactive mass transport of major cement constituents and aggressive species (e.g., chloride, sulfate, etc.). The CBP issued numerous reports and other documentation that accompanied the “Version 1.0” release including a CBP Software Toolbox User Guide and Installation Guide. These documents, as well as, the

  17. Adsorption of cesium on cement mortar from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Volchek, Konstantin, E-mail: konstantin.volchek@ec.gc.ca [Emergencies Science and Technology Section, Environment Canada, 335 River Road, Ottawa, Ontario, Canada K1A 0H3 (Canada); Miah, Muhammed Yusuf [Emergencies Science and Technology Section, Environment Canada, 335 River Road, Ottawa, Ontario, Canada K1A 0H3 (Canada); Department of Applied Chemistry and Chemical Technology, Noakhali Science and Technology University (Bangladesh); Kuang, Wenxing; DeMaleki, Zack [Emergencies Science and Technology Section, Environment Canada, 335 River Road, Ottawa, Ontario, Canada K1A 0H3 (Canada); Tezel, F. Handan [Department of Chemical and Biological Engineering, University of Ottawa, 161 Louis-Pasteur, Ottawa, Ontario, Canada K1N 6N5 (Canada)

    2011-10-30

    Highlights: {yields} The adsorption of cesium on cement mortar was investigated in a range of temperatures and cesium concentrations. {yields} The pseudo-second order kinetic model produced a good fit with the experimental kinetic data. {yields} Equilibrium test results correlated well with the Freundlich isotherm adsorption model. {yields} The interaction between cesium ions and cement mortar was dominated by chemical adsorption. - Abstract: The adsorption of cesium on cement mortar from aqueous solutions was studied in series of bench-scale tests. The effects of cesium concentration, temperature and contact time on process kinetics and equilibrium were evaluated. Experiments were carried out in a range of initial cesium concentrations from 0.0103 to 10.88 mg L{sup -1} and temperatures from 278 to 313 K using coupons of cement mortar immersed in the solutions. Non-radioactive cesium chloride was used as a surrogate of the radioactive {sup 137}Cs. Solution samples were taken after set periods of time and analyzed by inductively coupled plasma mass spectroscopy. Depending on the initial cesium concentration, its equilibrium concentration in solution ranged from 0.0069 to 8.837 mg L{sup -1} while the respective surface concentration on coupons varied from 0.0395 to 22.34 {mu}g cm{sup -2}. Equilibrium test results correlated well with the Freundlich isotherm model for the entire test duration. Test results revealed that an increase in temperature resulted in an increase in adsorption rate and a decrease in equilibrium cesium surface concentration. Among several kinetic models considered, the pseudo-second order reaction model was found to be the best to describe the kinetic test results in the studied range of concentrations. The adsorption activation energy determined from Arrhenius equation was found to be approximately 55.9 kJ mol{sup -1} suggesting that chemisorption was the prevalent mechanism of interaction between cesium ions and cement mortar.

  18. The adherence in the union stone-mortar

    Directory of Open Access Journals (Sweden)

    Rodríguez García, María Reyes

    1994-06-01

    Full Text Available Stones placates present a wide of problems that result in the fall of plates. One of the causes is the lack of adherence stone-mortar. We considered a study to determine the adherence between several cement mortars (1:3, 1:5, 1:7, 1:9 and a especial mortar prepared with latex and stones (white granite, pink granites, black granites, white marble and cream limestones. The results obtained suggest that only adequate adherence rates (higher than 3 kgf/cm2 achieved with cement mortar 1:3 and especial mortar. Besides it is observed that in the stones studied there is no relation between adherence and the absorption values.

    Los aplacados de piedra presentan una extensa patología que se traduce en la caída de las placas colocadas. Una de las causas es la falta de adherencia mortero-piedra. El estudio se realiza para determinar la tensión de adherencia entre diversos morteros de cemento (1:3, 1:5, 1:7, 1:9 y otro compuesto por mortero y látex y piedras (granito blanco, granitos rosa, granitos negros, mármol blanco y calizas crema. De los resultados obtenidos se deduce que los únicos morteros que permiten valores de adherencia aceptables (superiores a 3 kp/cm2 son el mortero de cemento 1:3 y el especial. Igualmente se comprueba que, en las piedras estudiadas, no existe relación alguna entre la adherencia y la absorción de agua.

  19. Strengthening masonry infill panels using engineered cementitious composites

    DEFF Research Database (Denmark)

    Dehghani, Ayoub; Fischer, Gregor; Nateghi Alahi, Fariborz

    2015-01-01

    ECC in order to assess its distinctive mechanical properties such as tensile stress–strain behavior and multiple cracking. To investigate the influence of a thin layer of ECC on plain masonry in terms of changes in stiffness, strength, and deformability, small scale tests have been conducted on......This comprehensive experimental study aims at investigating the behavior of masonry infill panels strengthened by fiber reinforced engineered cementitious composites (ECC). The experimental program included testing of materials, masonry elements and panels. Material tests were carried out first for...

  20. Engineering Properties and Correlation Analysis of Fiber Cementitious Materials

    OpenAIRE

    Wei-Ting Lin; Yuan-Chieh Wu; An Cheng; Sao-Jeng Chao; Hui-Mi Hsu

    2014-01-01

    This study focuses on the effect of the amount of silica fume addition and volume fraction of steel fiber on the engineering properties of cementitious materials. Test variables include dosage of silica fume (5% and 10%), water/cement ratio (0.35 and 0.55) and steel fiber dosage (0.5%, 1.0% and 2.0%). The experimental results included: compressive strength, direct tensile strength, splitting tensile strength, surface abrasion and drop-weight test, which were collected to carry out the analysi...

  1. Impact of carbonation on water transport properties of cementitious materials

    International Nuclear Information System (INIS)

    Carbonation is a very well-known cementitious materials pathology. It is the major cause of reinforced concrete structures degradation. It leads to rebar corrosion and consequent concrete cover cracking. In the framework of radioactive waste management, cement-based materials used as building materials for structures or containers would be simultaneously submitted to drying and atmospheric carbonation. Although scientific literature regarding carbonating is vast, it is clearly lacking information about the influence of carbonation on water transport properties. This work then aimed at studying and understanding the change in water transport properties induced by carbonation. Simultaneously, the representativeness of accelerated carbonation (in the laboratory) was also studied. (author)

  2. Modelling for the mechanical behavior of cementitious granular materials

    Science.gov (United States)

    Zhong, Xiaoxiong

    Crack damages due to load application are commonly observed in cementitious granular materials such as concrete, cemented sand, and ceramic materials. Previous analytical models for these types of materials have been developed based on continuum mechanics using a phenomenological approach. However, the theories of continuum mechanics have limitations when used for analyzing fracture mechanism and localized damages at a micro-scale level. Therefore, a microstructural approach is desirable for the analysis of these types of materials. In this dissertation, a contact law was derived for the inter-particle behavior of two particles connected by a cement binder. Microcracking process within binder was fully taken into account by regarding crack length as a basic damage factor. The binder initially contains small-size cracks which propagate and grow under external loading. As a result the binder is weakened with lower strength in shear and tension. Theory of fracture mechanics was employed to model the propagation and growth of these microcracks for both the shear fracture mode and normal fracture mode. The contact law was then incorporated in the analysis for the overall damage behaviors of cementitious granular material using the statistical micromechanics approach and the distinct element method. These overall damage behaviors include the stress-strain relationship, fracture strength, development of damage zone, and fatigue deformation. The micro-parameters affecting these behaviors are mainly the microcrack length and density, binder toughness, and binder elastic constants. In the numerical simulations, the cementitious granular materials were represented by 2-D random assemblies of rods bonded by cement binders with preexisting microcracks. Stress-strain relationships were modeled and validated for the uniaxial tension and compression tests, biaxial tension and compression tests, and double cantilever beam test. Force-deflection relationship and fatigue deformation

  3. Neutron Radiography Based Visualization and Profiling of Water Uptake in (Uncracked and Autonomously Healed Cementitious Materials

    Directory of Open Access Journals (Sweden)

    Philip Van den Heede

    2016-04-01

    Full Text Available Given their low tensile strength, cement-based materials are very susceptible to cracking. These cracks serve as preferential pathways for corrosion inducing substances. For large concrete infrastructure works, currently available time-consuming manual repair techniques are not always an option. Often, one simply cannot reach the damaged areas and when making those areas accessible anyway (e.g., by redirecting traffic, the economic impacts involved would be enormous. Under those circumstances, it might be useful to have concrete with an embedded autonomous healing mechanism. In this paper, the effectiveness of incorporating encapsulated high and low viscosity polyurethane-based healing agents to ensure (multiple crack healing has been investigated by means of capillary absorption tests on mortar while monitoring the time-dependent water ingress with neutron radiography. Overall visual interpretation and water front/sample cross-section area ratios as well as water profiles representing the area around the crack and their integrals do not show a preference for the high or low viscosity healing agent. Another observation is that in presence of two cracks, only one is properly healed, especially when using the latter healing agent. Exposure to water immediately after release of the healing agent stimulates the foaming reaction of the polyurethane and ensures a better crack closure.

  4. Influence of Superplasticizers on Strength and Shrinkage Cracking of Cement Mortar under Drying Conditions

    Institute of Scientific and Technical Information of China (English)

    MA Baoguo; WANG Xin'gang; LI Xiangguo; YANG Lei

    2007-01-01

    The effects of polynaphthalene series superplasticizers(PNS) with a low content of sodium sulfate (H-UNF),with a high content of sodium sulfate(C-UNF) and polycarboxylate type superplasticizer (PC) on strength and shrinkage cracking of cement mortar under drying conditions were investigated by means of multi-channel ellipse ring shrinkage cracking test, free shrinkage and strength test. The general effect of PNS and PC is to increase the initial cracking time of mortars, and decrease the cracking sensitivity of mortars. As for decreasing the cracking sensitivity of mortars, PC>H-UNF>C-UNF. To incorporate superplasticizers is apparently to increase the free shrinkage of mortars when keeping the constant w/b ratio and the content of cement pastes. As for the effect of controlling the volume stability of mortars, PC>C-UNF>H-UNF. Maximum crack width of mortars containing PC is lower, but the development rate of maximum crack width of mortars containing H-UNF is faster in comparison with control mortars. The flexural and compressive strengths of mortars at 28-day increase with increasing superplasticizer dosages under drying conditions. PC was superior to PNS in the aspect of increasing strength.

  5. Influence Of Volcanic Scoria On Mechanical Strength, Chemical Resistance And Drying Shrinkage Of Mortars

    Directory of Open Access Journals (Sweden)

    Al-Swaidani A.

    2014-09-01

    Full Text Available In the study, three types of cement have been prepared; one CEM I type (the control sample and two blended cements: CEM II/A-P and CEM II/B-P (EN 197-1, each of them with three replacement levels of volcanic scoria: (10 %, 15 %, 20 % wt. and (25 %, 30 %, 35 % wt., respectively. Strength development of mortars has been investigated at 2, 7, 28 and 90 days curing. Evaluation of chemical resistance of mortars containing scoria-based cements has been investigated through exposure to 5 % sulphate and 5 % sulphuric acid solutions in accordance with ASTM C1012 & ASTM 267, respectively. Drying shrinkage has been evaluated in accordance with ASTM C596. Test results showed that at early ages, the mortars containing CEM II/B-P binders had strengths much lower than that of the control mortar. However, at 90 days curing, the strengths were comparable to the control mortar. In addition, the increase of scoria significantly improved the sulphate resistance of mortars. Further, an increase in scoria addition improved the sulphuric acid resistance of mortar, especially at the early days of exposure. The results of drying shrinkage revealed that the CEM II/B-P mortar bars exhibited a greater contraction when compared to the control mortar, especially at early ages. However, drying shrinkage of mortars was not influenced much at longer times.

  6. Inhibition of Cracks on the Surface of Cement Mortar Using Estabragh Fibers

    Directory of Open Access Journals (Sweden)

    Tahereh Soleimani

    2013-01-01

    Full Text Available The influence of adding Estabragh fibers into the cement composites of mortar on surface cracks and mechanical properties of mortar has been studied at various fiber proportions of 0.25%, 0.5%, and 0.75%. The mortar shrinkage was evaluated by counting the number of cracks and measuring the width of cracks on the surface of mortar specimens. Although the Estabragh fibers loss their strength in an alkali environment of cement composites, the ability of Estabragh fibers to bridge on the microcracks in the mortar matrix causes a decrease in the number of cracks and in their width on the surface of the mortar samples in comparison with the plain mortar. However, considering the mechanical properties of specimens such as bending strength and compressive strength, among all fiber proportions, only the specimens with 0.25% of Estabragh fiber performed better in all respects compared to the physical and mechanical properties of reinforced cement composite of mortar. Consequently, by adding 0.25% of Estabragh fibers to the cement mortar, a remarkable inhibition in crack generation on fiber-containing cement composite of mortar is achieved.

  7. Interaction of low pH cementitious concretes with groundwaters

    International Nuclear Information System (INIS)

    Some engineering construction concepts for high level radioactive waste underground repositories consider the use of a bentonite barrier in contact with cementitious materials with a pore fluid pH value inferior or equal to 11 (based on low-pH cements) to maintain the bentonite stability. The research on low-pH cementitious materials is mainly addressed from two different approaches, one with Calcium Silicate Cements (OPC, Ordinary Portland Cement based), the other with Calcium Aluminates Cements (CAC based). The use of these both types of cements (OPC based or CAC based) implies the use of high mineral additions contents in the binder that should significantly modify most of the concrete 'standard' properties. Taking into account the long life expected in this type of repositories, parameters related to the durability of the low-pH concretes must be analyzed. This work shows some recent studies that deal with the evaluation of the resistance of low-pH concretes to long term groundwater aggression. After a presentation of the accelerated leaching test (based on a percolation method), results are given for the characterization of the leaching solution evolution and the evaluation of the modifications generated in the solid phases. Results show that the low-pH concretes evaluated have good resistance against groundwater interaction, although an altered front can be observed from the surface in all the tested samples

  8. Engineering Properties and Correlation Analysis of Fiber Cementitious Materials

    Directory of Open Access Journals (Sweden)

    Wei-Ting Lin

    2014-11-01

    Full Text Available This study focuses on the effect of the amount of silica fume addition and volume fraction of steel fiber on the engineering properties of cementitious materials. Test variables include dosage of silica fume (5% and 10%, water/cement ratio (0.35 and 0.55 and steel fiber dosage (0.5%, 1.0% and 2.0%. The experimental results included: compressive strength, direct tensile strength, splitting tensile strength, surface abrasion and drop-weight test, which were collected to carry out the analysis of variance to realize the relevancy and significance between material parameters and those mechanical properties. Test results illustrate that the splitting tensile strength, direct tensile strength, strain capacity and ability of crack-arresting increase with increasing steel fiber and silica fume dosages, as well as the optimum mixture of the fiber cementitious materials is 5% replacement silica fume and 2% fiber dosage. In addition, the Pearson correlation coefficient was conducted to evaluate the influence of the material variables and corresponds to the experiment result.

  9. Evaluation of electric properties of cement mortars containing pozzolans

    Directory of Open Access Journals (Sweden)

    Cruz, J. M.

    2011-03-01

    Full Text Available In this paper the evolution of the microstructure of Portland cement mortar is analyzed, by using electrical impedance measurements. Cement mortars are compared without and with two pozzolanic substitutions: spent fluid catalytic cracking catalyst (FCC and metakaolin (MK. The measurement method is described and the model for analyzing the electrical impedance spectra is developed. Three electrical parameters are defined: electrical resistivity, capacitance exponent, and capacitive factor. The results show a significant increase in resistivity of the mortars with pozzolans after 7 days of curing, especially in mortars with MK. This increase is correlated with lime-fixing by the pozzolans. The capacitive properties evolve differently at early age, but reach the same values after 148 days. The electrical and mineralogical data show that the evolution of the microstructure in the mortar with MK starts before it does in the mortars with FCC and that the final microstructure becomes different.

    En este trabajo se analiza la microestructura de morteros de cemento Portland, mediante medidas de impedancia eléctrica. Se comparan morteros de cemento sin y con dos sustituciones puzolánicas: residuo de catalizador de craqueo catalítico (FCC y metacaolín (MK. Se describe el método de medida y se desarrolla el modelo de análisis de los espectros de impedancia eléctrica. Se definen tres parámetros eléctricos: resistividad eléctrica, exponente capacitivo, y factor capacitivo. Se observa un aumento importante de la resistividad de los morteros con puzolana a partir de los 7 días de curado, sobre todo en morteros con MK. Este aumento está correlacionado con la fijación de cal de las puzolanas. Las propiedades capacitivas son diferentes a edad temprana, pero se igualan a los 148 días. Los resultados eléctricos y mineralógicos muestran que la evolución microestructural comienza antes en los morteros con MK que con FCC y que la microestructura

  10. VARIABILITY OF KD VALUES IN CEMENTITIOUS MATERIALS AND SEDIMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Almond, P.; Kaplan, D.; Shine, E.

    2012-02-02

    Measured distribution coefficients (K{sub d} values) for environmental contaminants provide input data for performance assessments (PA) that evaluate physical and chemical phenomena for release of radionuclides from wasteforms, degradation of engineered components and subsequent transport of radionuclides through environmental media. Research efforts at SRNL to study the effects of formulation and curing variability on the physiochemical properties of the saltstone wasteform produced at the Saltstone Disposal Facility (SDF) are ongoing and provide information for the PA and Saltstone Operations. Furthermore, the range and distribution of plutonium K{sub d} values in soils is not known. Knowledge of these parameters is needed to provide guidance for stochastic modeling in the PA. Under the current SRS liquid waste processing system, supernate from F & H Tank Farm tanks is processed to remove actinides and fission products, resulting in a low-curie Decontaminated Salt Solution (DSS). At the Saltstone Production Facility (SPF), DSS is mixed with premix, comprised of blast furnace slag (BFS), Class F fly ash (FA), and portland cement (OPC) to form a grout mixture. The fresh grout is subsequently placed in SDF vaults where it cures through hydration reactions to produce saltstone, a hardened monolithic waste form. Variation in saltstone composition and cure conditions of grout can affect the saltstone's physiochemical properties. Variations in properties may originate from variables in DSS, premix, and water to premix ratio, grout mixing, placing, and curing conditions including time and temperature (Harbour et al. 2007; Harbour et al. 2009). There are no previous studies reported in the literature regarding the range and distribution of K{sub d} values in cementitious materials. Presently, the Savannah River Site (SRS) estimate ranges and distributions of K{sub d} values based on measurements of K{sub d} values made in sandy SRS sediments (Kaplan 2010). The actual

  11. Technetium Sorption By Cementitious Materials Under Reducing Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kaplan, Daniel I. [Savannah River National Lab., Aiken, SC (United States); Estes, Shanna L. [Clemson Univ., SC (United States). Environmental Engineering and Earth Sciences; Arai, Yuji [Clemson Univ., SC (United States). College of Agriculture, Forestry and Life Sciences; Powell, Brian A. [Clemson Univ., SC (United States). Environmental Engineering and Earth Sciences

    2013-07-18

    The objective of this study was to measure Tc sorption to cementitious materials under reducing conditions to simulate Saltstone Disposal Facility conditions. Earlier studies were conducted and the experimental conditions were found not to simulate those of the facility. Through a five month subcontract with Clemson University, sorption of {sup 99}Tc to four cementitious materials was examined within an anaerobic glovebag targeting a 0.1% H{sub 2}(g)/ 99.9% N{sub 2}(g) atmosphere. Early experiments based on Tc sorption and Eh indicated that 0.1% H{sub 2}(g) (a reductant) was necessary to preclude experimental impacts from O{sub 2}(g) diffusion into the glovebag. Preliminary data to date (up to 56 days) indicates that sorption of {sup 99}Tc to cementitious materials increased with increasing slag content for simulated saltstone samples. This is consistent with the conceptual model that redox active sulfide groups within the reducing slag facilitate reduction of Tc(VII) to Tc(IV). These experiments differ from previous experiments where a 2% H{sub 2}(g) atmosphere was maintained (Kaplan et al., 2011 (SRNL-STI-2010-00668)). The impact of the 2% H{sub 2}(g) reducing atmosphere on this data was examined and determined to cause the reduction of Tc in experimental samples without slag. In the present ongoing study, after 56 days, Tc sorption by the 50-year old cement samples (no slag) was undetectable, whereas Tc sorption in the cementitious materials containing slag continues to increase with contact time (measured after 1, 4, 8, 19 and 56 days). Sorption was not consistent with spike concentrations and steady state has not been demonstrated after 56 days. The average conditional K{sub d} value for the Vault 2 cementitious material was 873 mL/g (17% slag), for the TR547 Saltstone (45% slag) the conditional K{sub d} was 168 mL/g, and for TR545 (90% slag) the conditional K{sub d} was 1,619 mL/g. It is anticipated that additional samples will be collected until steady state

  12. Degradation Of Cementitious Materials Associated With Saltstone Disposal Units

    Energy Technology Data Exchange (ETDEWEB)

    Flach, G. P; Smith, F. G. III

    2013-03-19

    The Saltstone facilities at the DOE Savannah River Site (SRS) stabilize and dispose of low-level radioactive salt solution originating from liquid waste storage tanks at the site. The Saltstone Production Facility (SPF) receives treated salt solution and mixes the aqueous waste with dry cement, blast furnace slag, and fly ash to form a grout slurry which is mechanically pumped into concrete disposal cells that compose the Saltstone Disposal Facility (SDF). The solidified grout is termed “saltstone”. Cementitious materials play a prominent role in the design and long-term performance of the SDF. The saltstone grout exhibits low permeability and diffusivity, and thus represents a physical barrier to waste release. The waste form is also reducing, which creates a chemical barrier to waste release for certain key radionuclides, notably Tc-99. Similarly, the concrete shell of an SDF disposal unit (SDU) represents an additional physical and chemical barrier to radionuclide release to the environment. Together the waste form and the SDU compose a robust containment structure at the time of facility closure. However, the physical and chemical state of cementitious materials will evolve over time through a variety of phenomena, leading to degraded barrier performance over Performance Assessment (PA) timescales of thousands to tens of thousands of years. Previous studies of cementitious material degradation in the context of low-level waste disposal have identified sulfate attack, carbonation influenced steel corrosion, and decalcification (primary constituent leaching) as the primary chemical degradation phenomena of most relevance to SRS exposure conditions. In this study, degradation time scales for each of these three degradation phenomena are estimated for saltstone and concrete associated with each SDU type under conservative, nominal, and best estimate assumptions. The nominal value (NV) is an intermediate result that is more probable than the conservative

  13. Variability Of KD Values In Cementitious Materials And Sediments

    International Nuclear Information System (INIS)

    Measured distribution coefficients (Kd values) for environmental contaminants provide input data for performance assessments (PA) that evaluate physical and chemical phenomena for release of radionuclides from wasteforms, degradation of engineered components and subsequent transport of radionuclides through environmental media. Research efforts at SRNL to study the effects of formulation and curing variability on the physiochemical properties of the saltstone wasteform produced at the Saltstone Disposal Facility (SDF) are ongoing and provide information for the PA and Saltstone Operations. Furthermore, the range and distribution of plutonium Kd values in soils is not known. Knowledge of these parameters is needed to provide guidance for stochastic modeling in the PA. Under the current SRS liquid waste processing system, supernate from F and H Tank Farm tanks is processed to remove actinides and fission products, resulting in a low-curie Decontaminated Salt Solution (DSS). At the Saltstone Production Facility (SPF), DSS is mixed with premix, comprised of blast furnace slag (BFS), Class F fly ash (FA), and portland cement (OPC) to form a grout mixture. The fresh grout is subsequently placed in SDF vaults where it cures through hydration reactions to produce saltstone, a hardened monolithic waste form. Variation in saltstone composition and cure conditions of grout can affect the saltstone's physiochemical properties. Variations in properties may originate from variables in DSS, premix, and water to premix ratio, grout mixing, placing, and curing conditions including time and temperature (Harbour et al. 2007; Harbour et al. 2009). There are no previous studies reported in the literature regarding the range and distribution of Kd values in cementitious materials. Presently, the Savannah River Site (SRS) estimate ranges and distributions of Kd values based on measurements of Kd values made in sandy SRS sediments (Kaplan 2010). The actual cementitious material Kd values

  14. Homogeneity and Strength of Mortar Joints in Pearl-Chain Bridges

    DEFF Research Database (Denmark)

    Lund, Mia Schou Møller; Arvidsson, Michael; Hansen, Kurt Kielsgaard

    2015-01-01

    been tested and compared by measuring compressive strength, variation in rebound value, variation in density, and separation. In addition, the appearance of the surface texture has been visually assessed. The measurements indicate that, for all three mortars tested, it is possible to cast homogeneous 2......The load carrying mortar joints in Pearl-Chain Bridges are cast vertically which means that they have a placing depth of up to 2.40 m. In the present paper, the feasibility of casting 2.40 m high homogeneous vertical mortar joints is examined. Three high-strength, expansive, self-compacting, ready......-to-mix mortar products are tested. To the authors’ knowledge, no previous published work has documented the homogeneity and properties of mortar joints of such a height. Hence, the present study documents a practical test procedure where the homogeneity of three mortar joints measuring 20 x 220 x 2400 mm has...

  15. Pozzolanic mortars based on waste building materials for the restoration of historical buildings

    Directory of Open Access Journals (Sweden)

    Pašalić Snežana

    2012-01-01

    Full Text Available The environmental aspects of waste building materials have been of great interest in recent years. For the sector of building materials this means increased recycling, reduction of energy consumption and natural resources preservation. This also presents an important contribution in the field of environmental protection. The work deals with the development of pozzolanic mortars made of waste building materials, ground red structure bricks and raw clay materials of inadequate characteristics for the production of ceramic materials. Based on the results of historical mortar characterizations, a group of mortars with specific characteristics (satisfied durability, good compatibility with a historical mortar was prepared. The potential of the waste materials and domestic clay materials application in the production of pozzolanic mortars was confirmed. In addition to the waste management, pozzolanic mortars were designed taking into account the existing conventions in the area of culture heritage.

  16. Plastic shrinkage of mortars with shrinkage reducing admixture and lightweight aggregates studied by neutron tomography

    Energy Technology Data Exchange (ETDEWEB)

    Wyrzykowski, Mateusz, E-mail: mateusz.wyrzykowski@empa.ch [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Dübendorf (Switzerland); Lodz University of Technology, Department of Building Physics and Building Materials, Lodz (Poland); Trtik, Pavel [Paul Scherrer Institute, Laboratory for Neutron Scattering and Imaging, Villigen (Switzerland); Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Dübendorf (Switzerland); Münch, Beat [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Dübendorf (Switzerland); Weiss, Jason [Purdue University, School of Civil Engineering, West Lafayette (United States); Vontobel, Peter [Paul Scherrer Institute, Laboratory for Neutron Scattering and Imaging, Villigen (Switzerland); Lura, Pietro [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Dübendorf (Switzerland); ETH Zurich, Institute for Building Materials (IfB), Zurich (Switzerland)

    2015-07-15

    Water transport in fresh, highly permeable concrete and rapid water evaporation from the concrete surface during the first few hours after placement are the key parameters influencing plastic shrinkage cracking. In this work, neutron tomography was used to determine both the water loss from the concrete surface due to evaporation and the redistribution of fluid that occurs in fresh mortars exposed to external drying. In addition to the reference mortar with a water to cement ratio (w/c) of 0.30, a mortar with the addition of pre-wetted lightweight aggregates (LWA) and a mortar with a shrinkage reducing admixture (SRA) were tested. The addition of SRA reduced the evaporation rate from the mortar at the initial stages of drying and reduced the total water loss. The pre-wetted LWA released a large part of the absorbed water as a consequence of capillary pressure developing in the fresh mortar due to evaporation.

  17. The long term effect on cement mortar by admixture of spray drying absorption products

    International Nuclear Information System (INIS)

    Preliminary investigations have shown that the substitutions of up to 10% fly ash (FA), with spray drying absorption products (SDA), in cement mortars (cement: 80% rapid portland cement (RPC), 10-20% FA, 0-10% SDA) results in low early strength of the same magnitude as in mortar with 80% RPC + 20% FA. Use of the modified instructions for preparation of mortar prisms containing SDA resulted in satisfactory early strengths. A series of mortar prisms with increasing content of SDA (x% RPC, (100-x)% SDA in cements; 0 80% cannot be stored wet. The effects on mortars of the individual constituents of the SDA-products are studied by XRD, development in strength and density. Fragments of 2 year old SDA containing cement mortars and SDA containing concrete from a parking place have been studied

  18. Analytical characterisation of ancient mortars from the archaeological Roman city of Pollentia (Balearic Islands, Spain)

    International Nuclear Information System (INIS)

    Analytical characterisation of historic mortars from the Roman city of Pollentia (Mallorca) has been carried out by means of thermal analysis (thermogravimetry (TG) and derivative thermogravimetry (DTG)), X-ray diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR). The aim of this research is to provide useful information about the construction mode of the mortars which served for lining purposes in duct drains, cisterns, swimming pools, flooring mortars and wall renderings. The reported results converge to reveal the hydraulic nature of the majority of the mortars used for several hundred years to cover the diverse needs of the inhabitants of Pollentia. A fair correlation between the chemical characteristics of the studied mortars and the results of ancient Roman mortars from other archaeological sites has been established

  19. ESTIMATION OF CREEPING RESISTANCE OF AN ADHESIVE LAYER BASED ON DRY MORTAR

    Directory of Open Access Journals (Sweden)

    Loganina Valentina Ivanovna

    2016-04-01

    Full Text Available The development of construction materials with increased operational properties is a priority direction of Russian modern structural material science. Dry mortars are among such materials. Various modifiers are added to the formulae of such mixes in order to control their structure formation and increase the operational properties. Previous investigations proved the efficiency of adding synthetic zeolites to the composition of dry mortars. The authors of the article have developed a formula of a dry mortar to be used as a tile adhesive for facades’ and inner walls’ facing. The authors evaluated the operational properties of tile adhesive layer based on dry cement mortar. The authors calculated the value of adhesive layer creep based on the developed dry cement mortar formula, which was spread over a vertical surface. The experimental data is presented in the article. The calculations and the experimental data proved that the adhesive layer based on dry cement mortar possesses a high creeping resistance.

  20. Plastic shrinkage of mortars with shrinkage reducing admixture and lightweight aggregates studied by neutron tomography

    International Nuclear Information System (INIS)

    Water transport in fresh, highly permeable concrete and rapid water evaporation from the concrete surface during the first few hours after placement are the key parameters influencing plastic shrinkage cracking. In this work, neutron tomography was used to determine both the water loss from the concrete surface due to evaporation and the redistribution of fluid that occurs in fresh mortars exposed to external drying. In addition to the reference mortar with a water to cement ratio (w/c) of 0.30, a mortar with the addition of pre-wetted lightweight aggregates (LWA) and a mortar with a shrinkage reducing admixture (SRA) were tested. The addition of SRA reduced the evaporation rate from the mortar at the initial stages of drying and reduced the total water loss. The pre-wetted LWA released a large part of the absorbed water as a consequence of capillary pressure developing in the fresh mortar due to evaporation

  1. Effects of slag fineness on durability of mortars

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In recent years, the usages of by-products and wastes in industry have become more important. The importance of the sustainable development is also of increasing. The utilizations of wastes, as mineral admixture or fine aggregate, reduce the consumption of the natural resources and improve the durability of concrete. In this study, the effect of the fineness on the high temperature and sulphate resistances of concrete mortar specimens, produced with ground granulated blast-furnace slag (GBFS)replacing cement, is investigated. The compressive and flexural strength test results for all series related to durability effects,exposing temperature and solutions, exposure times for these durability effects, slag content and fineness are discussed. Consequently, the optimum slag contents are determined for producing the sulphate and high temperature resistant mortars.

  2. Fracture mechanics of polymer mortar made with recycled raw materials

    Directory of Open Access Journals (Sweden)

    Marco Antonio Godoy Jurumenha

    2010-12-01

    Full Text Available The aim of this work is to show that industrial residues could be used in construction applications so that production costs as well as environmental protection can be improved. The fracture properties of polymer mortar manufactured with recycled materials are investigated to evaluate the materials behaviour to crack propagation. The residues used in this work were spent sand from foundry industry as aggregate, unsaturated polyester resin from polyethylene terephthalate (PET as matrix and polyester textile fibres from garment industry, producing an unique composite material fully from recycled components with low cost. The substitution of fresh by used foundry sand and the insertions of textile fibres contribute to a less brittle behaviour of polymer mortar.

  3. Effect of temperature on the mechanical properties of polymer mortars

    Directory of Open Access Journals (Sweden)

    João Marciano Laredo dos Reis

    2012-08-01

    Full Text Available This paper presents the results of an experimental program to investigate the effect of temperature on the performance of epoxy and unsaturated polyester polymer mortars (PM. PM is a composite material in which polymeric materials are used to bond the aggregates in a fashion similar to that used in the preparation of Portland cement concrete. For this purpose, prismatic and cylindrical specimens were prepared for flexural and compressive tests, respectively, at different temperatures. Measurements of the temperature-dependent elastic modulus and the compressive and flexural strength were conducted using a thermostatic chamber attached to a universal test machine for a range of temperatures varying from room temperature to 90 ºC. The flexural and compressive strength decreases as temperature increases, especially after matrix HDT. Epoxy polymer mortars are more sensitive to temperature variation than unsaturated polyester ones.

  4. Fracture mechanics applied to the determination of adhesion strength between epoxies and hydraulic mortars

    OpenAIRE

    Aguiar, J. L. Barroso de

    2001-01-01

    The determination of adhesion strength between polymers and mortars always creates problems. The use of traditional tests like direct tension, flexure or shear, normally doesn`t make possible the correct determination of the adhesion strength. If the adhesive is good and the mortar surfaces are well prepared, the failure is in the mortar. With this kind of failures it is possible to say that adhesion strength is higher than the failure stress. But is not possible to give a numerical value of ...

  5. CASCADIC MULTIGRID METHODS FOR MORTAR WILSON FINITE ELEMENT METHODS ON PLANAR LINEAR ELASTICITY

    Institute of Scientific and Technical Information of China (English)

    陈文斌; 汪艳秋

    2003-01-01

    Cascadic multigrid technique for mortar Wilson finite element method ofhomogeneous boundary value planar linear elasticity is described and analyzed. Firstthe mortar Wilson finite element method for planar linear elasticity will be analyzed,and the error estimate under L2 and H1 norm is optimal. Then a cascadic multigridmethod for the mortar finite element discrete problem is described. Suitable grid trans-fer operator and smoother are developed which lead to an optimal cascadic multigridmethod. Finally, the computational results are presented.

  6. Effect of water-repellent admixtures on the behaviour of aerial lime-based mortars

    OpenAIRE

    Izaguirre, A.; Lanas, J.; Alvarez, J I

    2009-01-01

    Two different anionic surfactants, sodium oleate and calcium stearate, commercialized as water repellents for cement-based mortars, were added to lime-based mortars in order to check whether they were improved by these admixtures. Different properties of lime-based mortars were evaluated: fresh state behaviour through water retention, air content and setting time, hardened state properties such as density, water absorption through capillarity, water vapour permeability, long-term compressive ...

  7. Improved cement mortars by addition of carbonated fly ash from solid waste incinerators

    OpenAIRE

    López-Zaldívar, O.; Mayor-Lobo, P. L.; Fernández-Martínez, F.; Hernández-Olivares, F.

    2015-01-01

    This article presents the results of a research developing high performance cement mortars with the addition of municipal solid waste incineration fly ash (MSWIFA) stabilized as insoluble carbonates. The encapsulation of hazardous wastes in mortar matrixes has also been achieved. The ashes present high concentrations of chlorides, Zn and Pb. A stabilization process with NaHCO3 has been developed reducing 99% the content of chlorides. Developed mortars replace 10% per weight of the aggregates ...

  8. Dry and wet "deposition" studies of the degradation of cement mortars

    OpenAIRE

    Martínez-Ramírez, S.; Thompson, G.E.

    1998-01-01

    The reaction of portland cement mortars with SO2 gaseous pollutant and artificial 'acid rain' solution has been examined using laboratory exposure chambers, with realistic presentation rates of pollutants. The mortar were previously carbonated to produce superficial carbonation. Two mortars with different w/c ratio and hence specific surface were prepared and exposed into the chambers. For dry deposition of SO2 pollutant gas, the important ro...

  9. Clay content of argillites: Influence on cement based mortars

    OpenAIRE

    Habert, Guillaume; CHOUPAY, Nathalie; Escadeillas, Gilles; MONTEL, Jean Marc; Guillaume, D

    2009-01-01

    The pozzolanic activity of four heated powders containing different clays has been tested. Mineral transformations during calcination from 20 to 900 °C have been followed by X-ray diffraction (XRD) and Differential Scanning Calorimetry (DSC). Compressive strength tests were performed at 1, 7 and 28 days on cement-clay mortars using 30% of pozzolanic material as a replacement by mass for cement. Calcination temperatures corresponded to the stages of potentially high reactivity identified by XR...

  10. Mortar and concrete based on calcium sulphate binders

    OpenAIRE

    Bakker, J.J.F.; Brouwers, H. J. H.

    2006-01-01

    In this study both hemi-hydrate and anhydrite are tested as calcium sulphate binders for structural mortar and concrete. The advantage of using calcium sulphates instead of cement as a binder is the fact that the production of calcium sulphate is more environmental friendly than that of cement. For the calcinations of Portland cement, temperatures up to 1480 oC are needed, while the calcination of for instance hemihydrate requires a temperature of 170 oC

  11. Calcium hydroxide based consolidation of lime mortars and stone

    Czech Academy of Sciences Publication Activity Database

    Drdácký, Miloš; Slížková, Zuzana

    Lisabon : LNEC, 2008 - (kk, k.), s. 299-308 ISBN 978-972-49-2135-8. [Stone consolidation in cultural heritage. Lisabon (PT), 06.05.2008-07.05.2008] R&D Projects: GA ČR(CZ) GA103/06/1609 Institutional research plan: CEZ:AV0Z20710524 Keywords : lime water * lime mortar consolidation * nanotechnology Subject RIV: AL - Art, Architecture, Cultural Heritage

  12. Hydrothermal interactions of cement or mortar with zeolites or montmorillonites

    International Nuclear Information System (INIS)

    Concretes, grouts, clays and/or zeolites are candidate borehole, shaft or tunnel plugging materials for any nuclear waste repository. Interactions between these plugging materials may take place under mild hydrothermal conditions during the life of a repository. Class H cement or motar (PSU/WES mixture) was reacted with one of two montmorillonites, clinoptilolite or mordenite at 1000 and 2000C for different periods under a confining pressure of 30 MPa. The solid reaction products were characterized by x-ray powder diffraction and scanning electron microscopy after the hydrothermal treatments. When zeolites were in contact (not intimate mixture) with class H cement, they did not seem to alter but clinoptilolite altered to analcime, and mordenite became poorly crystalline in the presence of mortar (containing NaCl) at both 1000 and 2000C. When cement or mortar was intimately mixed with zeolites or montmorillonites and reacted hydrothermally, the reaction resulted in the formation of Al substituted tobermorite (11A type) in all cases (this type of reaction is expected at the interface) at both 1000 and 2000C. The mechanism of tobermorite formation includes the decomposition of zeolites or montmorillonites in the presence of alkaline (pH approx. = 12) cement or mortar and recrystallization to form Al substituted tobermorite. Cesium sorption measurements in 0.01N CaCl2 on the reaction products revealed that selective Cs sorption increased in most cases, even though little or none of the original zeolites and montmorillonites remained in the products. For example, Cs sorption K/sub d/ (mL/g) increased from 80 in the untreated mortar + Ca montmorillonite mixture to 1700 in the interaction product which is Al substituted tobermorite. Thus, we discover here that Al substituted tobermorite has good selectivity for Cs

  13. Alkaline cement mortars. Chemical resistance to sulfate and seawater attack

    Directory of Open Access Journals (Sweden)

    Puertas, F.

    2002-09-01

    Full Text Available The durability and chemical resistance of alkali activated slag and fly ash/slag mortars in contact with sulfates and seawater media have been studied. Two methods were used in the evaluation of such durability: Kock-Steinegger and ASTM C1012. A mineralogical and a microstructural characterization of mortars were done at different ages of their conservation in aggressive media through XRD, SEM/ EDX and mercury porosimetry. Results showed a high durability of activated cement mortars in sulfates and seawater media. NaOH activated mortars are the most sensitive to environment attack with formation of expansive products as gypsum and ettringite, although in very low proportion.

    Se ha estudiado la estabilidad química en medios sulfáticos y de agua de mar de morteros de escorias activadas alcalinamente y morteros de mezclas de escoria y cenizas volantes activadas alcalinamente. Se han empleado dos métodos para evaluar dicha estabilidad: Kock-Steinegger y la norma ASTM C1012. Se ha realizado una caracterización mineralógica y micro estructural de los morteros (a diferentes edades de permanencia en los medios agresivos a través de DRX, SEM/EDX y porosimetría de mercurio. Los resultados obtenidos han demostrado la elevada durabilidad de todos los morteros de cementos activados estudiados frente a la agresividad de los sulfatos y del agua de mar Los morteros de escoria activada con NaOH son los más susceptibles al ataque por esos medios, conformación de productos expansivos como el yeso y la etringita, aunque en proporciones muy bajas.

  14. Use of Cassava Starch Waste as Adjoined of Covering Mortar

    OpenAIRE

    Eliane Hermes; Patrícia Gracieli Zembrzuski Pelissari; Djuliano Paz; Luana Boron; Carlos Alberto Mucelin

    2010-01-01

    This work aimed to study the reuse of the residual fiber of the cassava as material excels in civil construction, as adjoined of covering mortar. The waste used was obtained from an industry located in Missal - Paraná. Four different treatments were applied with 0, 10, 20 and 30% of fiber adding, assessing the mechanical and physical performance with respect to compression resistance, water retention, mass density, incorporated air content and retraction test. The compression resistance test ...

  15. Modelling anisotropic damage and permeability of mortar under dynamic loads

    OpenAIRE

    Chen, W.; MAUREL, O.; REESS, T.; MATALLAH, M.; FERRON, A.; C. La Borderie; G. Pijaudier-Cabot

    2011-01-01

    This paper deals with the development of a model for concrete subjected to dynamic loads. Shock waves are generated by Pulsed Arc Electro-hydraulic Discharges (PAED) in water and applied to mortar samples. A diphasic model (liquid water and vapour) is implemented in order to describe the electrical discharge and the propagation of shock waves in water. An anisotropic damage model is devised, which takes account of the strain rate effect and the crack closure effect. Coupling between anisotrop...

  16. Freezing and thawing resistance of aerial lime mortar with metakaolin\

    Czech Academy of Sciences Publication Activity Database

    Nunes, Cristiana Lara; Slížková, Zuzana

    2016-01-01

    Roč. 114, July (2016), s. 896-905. ISSN 0950-0618 R&D Projects: GA ČR(CZ) GBP105/12/G059 Institutional support: RVO:68378297 Keywords : freeze-thaw * lime * metakaolin * linseed oil * mortar * water-repellency Subject RIV: JN - Civil Engineering Impact factor: 2.296, year: 2014 http://www.sciencedirect.com/science/article/pii/S0950061816305645

  17. Recycling of copper tailings as an additive in cement mortars

    OpenAIRE

    Onuaguluchi, Obinna; EREN, Özgür

    2012-01-01

    Increasing demands for copper and copper allied products have made the processing of low grade ores with high volume waste output unavoidable. Presently, billions of tons of copper tailings can be found in major copper producing countries. The impact of copper tailings at 0%, 5% and 10% addition level by mass of cement on the fresh and hardened properties of mortars were determined. Results showed that dry copper tailings affect mixture consistency negatively. However, the use of pre-wetted t...

  18. Frost resistance of lime-based mortars with linseed oil

    Czech Academy of Sciences Publication Activity Database

    Nunes, Cristiana Lara; Slížková, Zuzana; Janotová, Dana

    Praha : Czech Technical University, Faculty of Transportation Sciences, 2012 - (Jiroušek, O.; Kytýř, D.), s. 23-26 ISBN 978-80-01-05062-0. [Bilateral Czech/German Symposium /13./. Telč (CZ), 05.06.2012-08.06.2012] Grant ostatní: MK CR(CZ) DF11P01OVV008 Keywords : mortar * linseed oil * durability Subject RIV: JM - Building Engineering

  19. Effects of PCA on Sulfate Attack Resistance of Mortar with Low w/c%PCA对低水灰比砂浆抗硫酸盐侵蚀的影响

    Institute of Scientific and Technical Information of China (English)

    胡飞龙; 蒋亚清; 顾越; 陈龙

    2013-01-01

    Different kinds of superplasticizers and cement with different content of C3A and CaCO3 and are used as raw materials. The compressive strength and flexural strength of cement mortar with low water-cement ratio are measured. And the influence of acrylic acid-type polycarboxylate admixture ( PCA- Ⅰ ) and maleic acid-type polycarboxylate admixture ( PCA- Ⅱ ) on sulfate resistance of cement mortar under different cementitious content were studied. The results show that optical polycarboxylate admixture should be chosen according to the mineral compostion and the C3A content of cement, thus low water-cement ratio cement mortar with polycarboxylate admixture added in showed better sulfate resistance.%以不同含量C3A和CaCO3的水泥以及不同的高效减水剂为原材料,对低水胶比水泥砂浆在硫酸盐环境下的抗压和抗折抗蚀系数等进行测试,研究了不同水泥成分条件下,丙烯酸类聚羧酸PCA-Ⅰ减水剂和马来酸类聚羧酸PCA-Ⅱ减水剂对低水灰比砂浆抗硫酸盐侵蚀性能的影响.结果表明,根据水泥矿物组成和C3A含量,合理确定聚羧酸减水剂品种,掺聚羧酸减水剂的低水灰比水泥砂浆具有良好的抗硫酸盐侵蚀性能.

  20. Alkali Aggregate Reaction in Alkali Slag Cement Mortars

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By means of "Mortar Bar Method",the ratio of cement to aggregate was kept as a constant 1∶2.25,the water-cement ratio of the mixture was 0.40,and six prism specimens were prepared for each batch of mixing proportions with dimensions of 10×10×60mm3 at 38±2℃ and RH≥95%, the influences of content and particle size of active aggregate, sort and content of alkali component and type of slag on the expansion ratios of alkali-activated slag cement(ASC) mortars due to alkali aggregate reaction(AAR) were studied. According to atomic absorption spectrometry,the amount of free alkali was measured in ASC mortars at 90d.The results show above factors affect AAR remarkably,but no dangerous AAR will occur in ASC system when the amount of active aggregate is below 15% and the mass fraction of alkali is not more than 5% (Na2O).Alkali participated in reaction as an independent component, and some hydrates containing alkali cations were produced, free alkalis in ASC system can be reduced enormously.Moreover,slag is an effective inhibitor, the possibility of generating dangerous AAR in ASC system is much lower at same conditions than that in ordinary Portland cement system.

  1. Link between microstructure and tritiated water diffusivity in mortars

    Directory of Open Access Journals (Sweden)

    Dangla P.

    2013-07-01

    Full Text Available Ions and radionuclide diffusivity in concrete is one of the most important factors that determine service life and safety assessment of cement based structures in nuclear power plants and radioactive-waste repositories. Apart from the influence of cement paste microstructure, the presence of aggregates may have an impact on transport properties of the material. The well-known interfacial transition zone, denoted by ITZ, is created near the aggregates and characterized by a greater porosity. The goal of this study is to investigate the competition between the more diffusing ITZ zone and the less diffusing aggregates. To this end, several series of tritiated water diffusion tests are conducted on mortars characterized by different water-to-cement ratios and sand volume fractions. In parallel, microstructure of these materials is explored by mercury and water porosimetry. It was observed that at low sand content (0% – 50%, diffusion properties of mortars are dominated by aggregates dilution effect. At 60% sand, diffusion increases significantly suggesting that percolation’s pores threshold has been reached. Results indicate also that sand particle size distribution has a great impact on the diffusivity of mortars.

  2. Link between microstructure and tritiated water diffusivity in mortars

    Science.gov (United States)

    Larbi, B.; Dridi, W.; Le Bescop, P.; Dangla, P.; Petit, L.

    2013-07-01

    Ions and radionuclide diffusivity in concrete is one of the most important factors that determine service life and safety assessment of cement based structures in nuclear power plants and radioactive-waste repositories. Apart from the influence of cement paste microstructure, the presence of aggregates may have an impact on transport properties of the material. The well-known interfacial transition zone, denoted by ITZ, is created near the aggregates and characterized by a greater porosity. The goal of this study is to investigate the competition between the more diffusing ITZ zone and the less diffusing aggregates. To this end, several series of tritiated water diffusion tests are conducted on mortars characterized by different water-to-cement ratios and sand volume fractions. In parallel, microstructure of these materials is explored by mercury and water porosimetry. It was observed that at low sand content (0% - 50%), diffusion properties of mortars are dominated by aggregates dilution effect. At 60% sand, diffusion increases significantly suggesting that percolation's pores threshold has been reached. Results indicate also that sand particle size distribution has a great impact on the diffusivity of mortars.

  3. Use of Cassava Starch Waste as Adjoined of Covering Mortar

    Directory of Open Access Journals (Sweden)

    Eliane Hermes

    2010-04-01

    Full Text Available This work aimed to study the reuse of the residual fiber of the cassava as material excels in civil construction, as adjoined of covering mortar. The waste used was obtained from an industry located in Missal - Paraná. Four different treatments were applied with 0, 10, 20 and 30% of fiber adding, assessing the mechanical and physical performance with respect to compression resistance, water retention, mass density, incorporated air content and retraction test. The compression resistance test demonstrated that the fibers addition decreased the mortar resistance, while concentrations of 10 and 20% have values close to the resistance offered by full mortar (0%. The addition of fibers caused a small decrease in the specific mass of composites with 20 and 30% of fibers and the incorporated air content showed a low variability in relation of the composites with fiber added and the full cementations matrix. In the test on the water retention the composition with the addition of 10% of fiber is that most resembles the full cementations matrix. The retraction tests showed that no had mass retraction in the differents percentages tested.

  4. Some masonary mortar from Hellenistic and Roman period Greece

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, H.H.G.

    1985-01-01

    The Mineral Resources Research Center at the University of Minnesota has been engaged for the past six years in projects to synthesize various hydraulic cements by plasma fusion. An analytical scheme was developed to examine the plasma products. The techniques used to examine these cements were applied to five masonary mortar samples of Hellenistic and Roman periods from three sites in Greece (Olympia, Larissa, and Trikkala). These were examined by chemical, microscopical (polarized light and scanning electron), x-ray diffraction, and differential thermal analysis methods. These samples are typical sand-lime mortars: The aggregates consist of quartz with small amounts of microcline or orthoclase and, in several of the samples, rock and chert fragments. The matrix is largely fine grained calcite and a small amount of calcium silicate hydrate, a typical phase found in hydraulic cements. The sample from the Altis in Olympia (160 to 170 A.D.) is a pink, dense mortar with medium to fine grained aggregate and shows excellent workmanship. This specimen contains reddish fragments which are probably pieces of ceramics which either are used as fill or are poorly crushed material added as a pozzolana. The samples were probably emplaced as a sand and slaked-lime mixture. The limes are impure and thus have feebly hydraulic properties.

  5. Fatigue behaviour analysis for the durability prequalification of strengthening mortars

    International Nuclear Information System (INIS)

    An innovative laboratory procedure used as a preliminary design stage for the pre-qualification of strengthening mortars applied to historical masonry buildings is described. In the analysis of the behaviour of masonry structures and their constituent materials, increasing importance has been assumed by the study of the long-term evolution of deformation and mechanical characteristics, which may be affected by both loading and environmental conditions. Through static and fatigue tests on mixed specimens historical brick-reinforced mortar it has been possible to investigate the durability of strengthening materials, in order to select, from a range of alternatives, the most suitable for the historical masonry. Cyclic fatigue stress has been applied to accelerate the static creep and to forecast the corresponding creep behaviour of the historical brick-strengthening mortar system under static long-time loading. This methodology has proved useful in avoiding the errors associated with materials that are not mechanically compatible and guarantees the durability of strengthening work. The experimental procedure has been used effectively in the biggest restoration building site in Europe, the Royal Palace of Venaria, and it is in progress of carrying out at the Special Natural Reserve of the Sacro Monte di Varallo, in Piedmont (Italy).

  6. Cement-mortar pipes as a source of aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Berend, K. [Diatel Curacao (Netherlands Antilles); Trouwborst, T. [EHCON b.v., Reeuwijk (Netherlands)

    1999-07-01

    In 1996 in Curacao, acute aluminum (Al) intoxication sickened patients in a dialysis center that used tap water to prepare dialysate. The mortality rate was 32%. A new factory-lined cement-mortar water distribution pipe had recently been installed. It is known that substantial amounts of barium, cadmium, and chromium can leach from cement-mortar linings. This article shows that high concentrations of Al can leach from cement mortars for at least two years in soft, aggressive water. The newly installed pipe, cement containing four times as much Al as usual, corrosive water, the high pH and temperature of the water, long residence time, and perhaps the corrosion inhibitor polyphosphate may have promoted this leaching. Certification of cements used to line water pipes is warranted. Central water treatment plants must distribute noncorrosive water, especially plants that use membrane desalination or other reverse osmosis or nanofiltration processes. Dialysis units should be promptly informed of any impending change in water treatment that might increase the Al content of tap water and also of any accidental pollution of the water distributed. Dialysis centers should always practice extended purification of tap water used for dialysate. Although Al as a risk factor for Alzheimer`s disease in the general population is still debated, there is no doubt that Al causes dialysis encephalopathy.

  7. Link between microstructure and tritiated water diffusivity in mortars

    International Nuclear Information System (INIS)

    Ions and radionuclide diffusivity in concrete is one of the most important factors that determine service life and safety assessment of cement based structures in nuclear power plants and radioactive-waste repositories. Apart from the influence of cement paste microstructure, the presence of aggregates may have an impact on transport properties of the material. The well-known interfacial transition zone, denoted by ITZ, is created near the aggregates and characterized by a greater porosity. The goal of this study is to investigate the competition between the more diffusing ITZ zone and the less diffusing aggregates. To this end, several series of tritiated water diffusion tests are conducted on mortars characterized by different water-to-cement ratios and sand volume fractions. In parallel, microstructure of these materials is explored by mercury and water porosimetry. It was observed that at low sand content (0% - 50%), diffusion properties of mortars are dominated by aggregates dilution effect. At 60% sand, diffusion increases significantly suggesting that percolation's pores threshold has been reached. Results indicate also that sand particle size distribution has a great impact on the diffusivity of mortars. (authors)

  8. Innovative Structural Materials and Sections with Strain Hardening Cementitious Composites

    Science.gov (United States)

    Dey, Vikram

    The motivation of this work is based on development of new construction products with strain hardening cementitious composites (SHCC) geared towards sustainable residential applications. The proposed research has three main objectives: automation of existing manufacturing systems for SHCC laminates; multi-level characterization of mechanical properties of fiber, matrix, interface and composites phases using servo-hydraulic and digital image correlation techniques. Structural behavior of these systems were predicted using ductility based design procedures using classical laminate theory and structural mechanics. SHCC sections are made up of thin sections of matrix with Portland cement based binder and fine aggregates impregnating continuous one-dimensional fibers in individual or bundle form or two/three dimensional woven, bonded or knitted textiles. Traditional fiber reinforced concrete (FRC) use random dispersed chopped fibers in the matrix at a low volume fractions, typically 1-2% to avoid to avoid fiber agglomeration and balling. In conventional FRC, fracture localization occurs immediately after the first crack, resulting in only minor improvement in toughness and tensile strength. However in SHCC systems, distribution of cracking throughout the specimen is facilitated by the fiber bridging mechanism. Influence of material properties of yarn, composition, geometry and weave patterns of textile in the behavior of laminated SHCC skin composites were investigated. Contribution of the cementitious matrix in the early age and long-term performance of laminated composites was studied with supplementary cementitious materials such as fly ash, silica fume, and wollastonite. A closed form model with classical laminate theory and ply discount method, coupled with a damage evolution model was utilized to simulate the non-linear tensile response of these composite materials. A constitutive material model developed earlier in the group was utilized to characterize and

  9. Potential of Carbon Nanotube Reinforced Cement Composites as Concrete Repair Material

    OpenAIRE

    Tanvir Manzur; Nur Yazdani; Md. Abul Bashar Emon

    2016-01-01

    Carbon nanotubes (CNTs) are a virtually ideal reinforcing agent due to extremely high aspect ratios and ultra high strengths. It is evident from contemporary research that utilization of CNT in producing new cement-based composite materials has a great potential. Consequently, possible practical application of CNT reinforced cementitious composites has immense prospect in the field of applied nanotechnology within construction industry. Several repair, retrofit, and strengthening techniques a...

  10. Interfacial (Fiber-matrix) Properties of High-strength Mortar (150 MPa) from Fiber Pullout

    DEFF Research Database (Denmark)

    Shannag, M.J.; Brincker, Rune; Hansen, Will

    1996-01-01

     The steel fiber-matrix properties of high-strength mortar (150 MPa), such as DSP (densified small particle), are obtained and compared to an ordinary strength mortar (40 MPa) using a specially designed fiber pullout apparatus. A new method for estimating the debonding energy of the interfacial......-strength DSP mortar has significantly improved interfacial properties compared to ordinary strength mortar. These results are important in the understanding of the role of steel fibers in improving the tensile properties of high-strength, brittle, cement-matrix composites....

  11. Analysis of main parameters affecting substrate/mortar contact area through tridimensional laser scanner.

    Science.gov (United States)

    Stolz, Carina M; Masuero, Angela B

    2015-10-01

    This study assesses the influence of the granulometric composition of sand, application energy and the superficial tension of substrates on the contact area of rendering mortars. Three substrates with distinct wetting behaviors were selected and mortars were prepared with different sand compositions. Characterization tests were performed on fresh and hardened mortars, as well as the rheological characterization. Mortars were applied to substrates with two different energies. The interfacial area was then digitized with 3D scanner. Results show that variables are all of influence on the interfacial contact in the development area. Furthermore, 3D laser scanning proved to be a good method to contact area measurement. PMID:26046982

  12. Recycling alternatives of converter slag in concrete and mortars

    International Nuclear Information System (INIS)

    The objective of this work is the study of the use of a residue of a steel plant (COSIPA-SP), constituted by magnetite, in components of the civil construction, aiming to increase the recycling and, consequently, to decrease the impact of that residue in the environment. To reach this objective, additions of this residue were tested in the formulation of concrete with the purpose of radiation shielding, as pellets in coarse aggregate, and as substitute of the fine fraction of sand in the composition of a coating mortar. The concrete produced with purpose of radiation shielding showed that for small residue additions (up to 30%), there was not significant variation in the mechanical properties, nor in the attenuation properties to the radiation. Therefore, it did not justify its addition for purpose of heavy concrete. The results obtained on pelletizing process show that the obtained pellets presented value of specific gravity (2,75 g.cm-3) very close to the one of the common crushed stone (2,55 g.cm-3 ), however, they presented a low resistance to the compression, (0,2 KN) for the pellets when compared to regular crushed stones (5,8 KN). These results show that its use could commit the mechanical resistance of the concrete without bringing any advantage on density increase or increment of radiation attenuation. The mortars produced by the addition of the fine residue in substitution to the sand, showed an improvement in the retention of water in green (95%), in comparison to the produced without residue (41%). Also, for ali the tested proportions of substitutions, the same resistance to the compression (approximately 40 MPa) was achieved The results of the leaching and solubility tests showed that even in case of largest amount of substitution of sand for residue (14,55%), there were not great variations on the analyzed elements in the extract, allowing to conclude that the residue behaved satisfactorily to the mortar. Its use as part of mortar composition showed

  13. Talc-based cementitious products: Effect of talc calcination

    Directory of Open Access Journals (Sweden)

    C.J. Ngally Sabouang

    2015-09-01

    Full Text Available This study reports the use of calcined talc for cementitious products making. The calcination is used to enhance the availability of magnesium from talc to react with phosphate for cement phase formation. It is shown that previous calcination of talc leads to products having enhanced mechanical performance due to the formation of more cement phase than in products based on raw talc. Talc fired at 900 °C was found to be the one in which magnesium release was maximal. Firing at temperature higher than 900 °C leads to the stabilization of enstatite, which decreased the magnesium availability. The cement phase is struvite, which was better detected on the X-ray patterns of the products involving fired talc. All the products have very rapid setting time and low shrinkage.

  14. Dynamic fracture behaviour in fibre-reinforced cementitious composites

    Science.gov (United States)

    Yu, Rena C.; Cifuentes, Héctor; Rivero, Ignacio; Ruiz, Gonzalo; Zhang, Xiaoxin

    2016-08-01

    The object of this work is to simulate the dynamic fracture propagation in fibre-reinforced cementitious composites, in particular, in steel fibre reinforced concrete (SFRC). Beams loaded in a three-point bend configuration through a drop-weight impact device are considered. A single cohesive crack is assumed to propagate at the middle section; the opening of this crack is governed by a rate-dependent cohesive law; the fibres around the fracture plane are explicitly represented through truss elements. The fibre pull-out behaviour is depicted by an equivalent constitutive law, which is obtained from an analytical load-slip curve. The obtained load-displacement curves and crack propagation velocities are compared with their experimental counterparts. The good agreement with experimental data testifies to the feasibility of the proposed methodology and paves the way to its application in a multi-scale framework.

  15. Innovation in use and research on cementitious material

    International Nuclear Information System (INIS)

    In this paper we discuss innovations in concrete technology which are currently being applied in the field-namely high and ultra high performance (strength), and self consolidating concrete. We discuss the factors which have enabled these developments and ongoing needs in these areas. The importance of sustainability as the major driver for future innovations and prospects for development of new cementitious materials with lower environmental impact is briefly discussed. Finally the importance of innovation in research is examined. The dramatic development in experimental and computational techniques over recent years opens up wide-ranging possibilities for understanding the micro- and nano- scale chemical and physical processes which underlie performance at a macroscopic level. The example of computational approaches at the atomic and molecular scale is presented in detail. In order to exploit the opportunities presented by such new techniques, there needs to be greater efforts to structure interdisciplinary, multi-group research

  16. Towards a mechanistic understanding of actinide retention by cementitious materials

    International Nuclear Information System (INIS)

    Full text of publication follows. Calcium silicate hydrate (C-S-H) are considered to be the most important constituent of hardened cement paste (HCP) with respect to their abundance and the diversity of structural sites exposed for cation and anion binding. Furthermore, C-S-H phases may control the long term release of radionuclides due to their stability during the evolution of the cementitious near field. The retention of Nd (III) by crystalline C-S-H phases has been studied by combined use of wet chemical methods, synchrotron based spectroscopic, laboratory-based X-ray diffraction techniques and an appropriate theoretical approach. The investigations enable us to propose a mechanistic model for the immobilisation of trivalent lanthanides and actinides in crystalline C-S-H phases. (authors)

  17. Computer Modeling of Leaching of Heavy Metal from Cementitious Waste

    Directory of Open Access Journals (Sweden)

    Peng Hu

    2013-07-01

    Full Text Available Thermodynamic equilibrium model was used to simulate the results of leaching heavy metal from cementitious wastes. Modeling results of the leached major element concentrations for samples agreed well with the leaching test using the set of pure minerals and solid solutions present in the database. The model revealed Pb and Cd were predominantly incorporated within the calcium silicate hydrate matrix while a greater portion of Cd exist as discrete particles in the cement pores. Precipitation was found to be the dominant mechanism controlling heavy metal solubility with carbonate and silicate species governing the solubility of Pb and carbonate, silicate and hydroxide species governing the solubility of Cd. In the presence of acetic acid, at low pH values Pb and Cd acetate complexes were predominant whereas, at high pH values, hydroxide species dominated. In the presence of municipal landfill leachate, Pb and Cd organic complexes dominated the heavy metal species in solution.

  18. Shear behavior of reinforced Engineered Cementitious Composites (ECC) beams

    DEFF Research Database (Denmark)

    Paegle, Ieva; Fischer, Gregor

    2010-01-01

    This paper describes an experimental investigation of the shear behavior of beams consisting of steel reinforced Engineered Cementitious Composites (ECC). Based on the strain hardening and multiple cracking behavior of ECC, this study investigates the extent to which ECC can improve the shear...... capacity of beams loaded primarily in shear and if ECC can partially or fully replace the conventional transverse steel reinforcement in beams. However, there is a lack of understanding of how the fibers affect the shear carrying capacity and deformation behavior of structural members if used either in...... randomly distributed PVA (polyvinyl alcohol) fiber beams with different stirrup spacing and reinforced concrete (RC) beams for comparison. Displacement and strain measurements taken using the ARAMIS photogrammetric data acquisition system by means of processing at high frame rate captured images of applied...

  19. Evaluation of natural colonisation of cementitious materials: Effect of bioreceptivity and environmental conditions

    OpenAIRE

    Manso Blanco, Sandra; Calvo-Torrás, María Angeles; De Belie, Nele; Segura Pérez, Ignacio; Aguado de Cea, Antonio

    2015-01-01

    Incorporation of living organisms, such as photosynthetic organisms, on the structure envelope has become a priority in the area of architecture and construction due to aesthetical, economic and ecological advantages. Important research efforts are made to achieve further improvements, such as for the development of cementitious materials with an enhanced bioreceptivity to stimulate biological growth. Previously, the study of the bioreceptivity of cementitious materials has been carried out m...

  20. Predicting the Probability of Failure of Cementitious Sewer Pipes Using Stochastic Finite Element Method

    OpenAIRE

    Alani, Amir M.; Asaad Faramarzi

    2015-01-01

    In this paper, a stochastic finite element method (SFEM) is employed to investigate the probability of failure of cementitious buried sewer pipes subjected to combined effect of corrosion and stresses. A non-linear time-dependant model is used to determine the extent of concrete corrosion. Using the SFEM, the effects of different random variables, including loads, pipe material, and corrosion on the remaining safe life of the cementitious sewer pipes are explored. A numerical example is prese...

  1. Characterization of historic mortars and earthen building materials in Abu Dhabi Emirate, UAE

    International Nuclear Information System (INIS)

    The Abu Dhabi Authority for Culture and Heritage (ADACH) is responsible for the conservation and management of historic buildings and archaeological sites in the Emirate. Laboratory analysis has been critical for understanding the composition of historic materials and establishing appropriate conservation treatments across a wide variety of building types, ranging from Iron Age earthen archaeological sites to late-Islamic stone buildings. Analysis was carried out on historic sites in Al Ain, Delma Island and Liwa Oasis using techniques such as micro-x-ray fluorescence (MXRF), scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM-EDX), polarized light microscopy (PLM), and x-ray diffraction (XRD). Testing was conducted through consultant laboratories and in collaboration with local universities. The initial aim of the analysis was to understand historic earthen materials and to confirm the suitability of locally sourced clays for the production of mud bricks and plasters. Another important goal was to characterize materials used in historic stone buildings in order to develop repair mortars, renders and grouts.

  2. Prepackaged polymer - modified mortar proves effective construction material - field and laboratory observations

    International Nuclear Information System (INIS)

    Hi-Bond - prepackaged polymer - modified mortar described in this paper is a revolutionary, multifunctional, high-tech, high performance, sustainable, durability improving group of construction materials with a high cost - benefit ratio. Hi-Bond has been developed by Dadabhoy Construction Technologies (Pvt) Ltd., (DCTL), Karachi, after extensive studies and research both locally and abroad. It can be used in floorings and pavings, integral waterproofing, adhesive applications, protective and decorative coatings, repairs, renovation, rehabilitation, anti corrosive linings, deck coverings, durability and efficiency improvement of canal linings and other hydraulic structures. Hi-Bond has been applied in various projects of national importance with great success for their repairs, renovation and rehabilitation and has also been tested and evaluated at various laboratories with highly encouraging results. Some examples include: (i) earthquake damaged bridge at Lora Nallah on Brewery Road, Quetta, (ii) fire damaged building of the daily Business Recorder House, Karachi, (iii) 200 - year old main dome of the tomb of Hazrat Shah Abdul Latif Bhitai, Bhitshah, Hyderabad, (iv) RCC shell roofs of Mehtab Biscuit and Wafers Factory, Sahiwal, (v) repair of newly built concrete floor on structural slab in a factory building at Karachi, (vi) Mohatta Palace, Clifton, Karachi, (vii) swimming pool at Okara Cantt, and (viii) numerous leaking basements, underground and overhead water reservoirs at and around Karachi including those of new vegetable market on super highway. Building Research Station, Government of the Punjab, Lahore also recommended the use of Hi-Bond in the applications mentioned above after testing and evaluation. The product was found easy in application and offered numerous technical and economical advantages, over conventional products, in variety of applications. It is important to note that shortly after the repairs and renovation of the building of the daily

  3. Mortar Upwind Finite Volume Element Method with Crouzeix-Raviart Element for Parabolic Convection Diffusion Problems

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper, we study the semi-discrete mortar upwind finite volume element method with the Crouzeix-Raviart element for the parabolic convection diffusion problems.It is proved that the semi-discrete mortar upwind finite volume element approximations derived are convergent in the H1- and L2-norms.

  4. The Roman mortars used in the construction of the Ponte di Augusto (Narni, Italy)

    Czech Academy of Sciences Publication Activity Database

    Drdácký, Miloš; Fratini, F.; Frankeová, Dita; Slížková, Zuzana

    2013-01-01

    Roč. 38, č. 1 (2013), s. 1117-1128. ISSN 0950-0618 R&D Projects: GA ČR(CZ) GBP105/12/G059 Institutional support: RVO:68378297 Keywords : historic mortar * roman mortar * Narni bridge Subject RIV: AL - Art, Architecture, Cultural Heritage Impact factor: 2.265, year: 2013

  5. Carbon fibre-reinforced, alkali-activated slag mortars

    Directory of Open Access Journals (Sweden)

    Garcés, P.

    2007-12-01

    Full Text Available The paper describes the effect of carbon fibre on alkaliactivated slag mortar (AAS mechanical strength, volume stability and reinforcing steel corrosion, compared to its effect on the same properties in Portland cement (PC properties. Mechanical strength and volume stability tests were performed as set out in the respective Spanish UNE standards. The corrosion rate of steel embedded in the specimens studied was determined from polarization resistance analysis. One of the findings of the study performed was that carbon fibre failed to improve AAS or CP mortar strength. As far as volume stability is concerned, the inclusion of carbon fibres in AAS with a liquid/solid ratio of 0.5 reduced drying shrinkage by about 50%. The effect of carbon fibre on PC mortars differed from its effect on AAS mortars. Studies showed that in the presence of carbonation, steel corrosion reached higher levels in carbon-fibre reinforced AAS mortars; the inclusion of 1% carbon fibre improved corrosion resistance perceptibly in these same mortars, however, when exposed to chloride attack.Se ha estudiado el efecto de la incorporación de fibras de carbón en el comportamiento mecánico, estabilidad de volumen y nivel de corrosión de la armadura en morteros de escorias activadas alcalinamente (AAS. Se evalúa la influencia de las fibras de carbón en el comportamiento de morteros alcalinos en comparación con el efecto que producen en morteros de Portland (CP. Los ensayos mecánicos y de estabilidad de volumen se han realizado según lo establecido en la norma UNE que los regula. Se ha utilizado la técnica de la Resistencia a la Polarización para determinar la velocidad de corrosión del acero embebido en las muestras estudiadas. Como consecuencia del estudio realizado, se ha podido concluir que la adición de fibras de carbón a morteros de AAS y CP no mejora las características resistentes de los mismos. En relación con la estabilidad de volumen, la incorporación de

  6. Microstructure and mechanical performance of modified mortar using hemp fibres and carbon nanotubes

    KAUST Repository

    Hamzaoui, Rabah

    2014-04-01

    Mechanical performance of modified mortar using hemp fibres is studied following various processing conditions. Hemp fibres combined with carbon nanotubes (CNT) are introduced in mortar and their effect is studied as function of curing time. The cement phase is replaced by different percentages of dry or wet hemp fibres ranging from 1.1. wt% up to 3.1. wt% whereas carbon nanotubes are dispersed in the aqueous solution. Our experimental results show that compressive and flexural strengths of wet fibres modified mortar are higher than those for dry hemp-mortar material. The achieved optimal percentage of wet hemp fibres is 2.1. wt% allowing a flexural strength higher than that of reference mortar. The addition of an optimal CNT concentration (0.01. wt%) combined with wet hemp has a reinforcing effect which turns to be related to an improvement of compressive and flexural strengths by 10% and 24%, respectively, in comparison with reference condition. © 2013 Elsevier Ltd.

  7. An electrochemical and microstructural characterization of steel-mortar admixed with corrosion inhibitors

    Institute of Scientific and Technical Information of China (English)

    Tuan; Anh; Nguyen; Recep; AVCI

    2009-01-01

    The present research brings new insights on the role of admixed corrosion inhibitors in the processes of cement hydration and rebar corrosion. The admixing of NaCl and the corrosion inhibitors in fresh mortar was found to alter the morphology and microstructure of the hardened mortar at the steel-mortar interfacial region. The admixing of the inhibitors increased the risk of carbonation of cement hydrates at the steel-mortar interfacial region, but partially displaced chloride ions. Chloride and the admixed inhibitors facilitated the formation of different cement hydrates and affected chloride binding at the steel-mortar interfacial region. The admixing of all three inhibitors was found to increase the polarization resistance of steel, indicating reduced corrosion rate of the steel over 48-day exposures to salt ponding.

  8. HEAT INSULATING LIME DRY MORTARS FOR FINISHING OF WALLS MADE OF FOAM CONCRETE

    Directory of Open Access Journals (Sweden)

    Loganina Valentina Ivanovna

    2016-05-01

    Full Text Available Different aerated mortars are used for pargeting of walls made of aerated concrete. Though the regulatory documents don’t specify the dependence of plaster density from the density grade of gas-concrete blocks. In case of facing of gas-concrete blocks with the grade D500 using plaster mortars with the density 1400…1600 km/m3 there occurs a dismatch in the values of thermal insulation and vapor permeability of the plaster and base. The authors suggest using dry mortars for finishing of gas-concrete block of the grades D500 и D600, which allow obtaining facing thermal insulating coatings. The efficiency of using four different high-porous additives in the lime dry mortar was compared. They were: hollow glass microspheres, aluminosilicate ash microspheres, expanded vermiculite sand, expanded pearlitic sand. The high efficiency of hollow glass microspheres in heat insulating finishing mortars compared to other fillers is proved.

  9. Mechanical properties of cement mortar in sodium sulfate and sodium chloride solutions

    Institute of Scientific and Technical Information of China (English)

    熊良宵; 虞利军

    2015-01-01

    To investigate the mechanical properties of cement mortar in sodium sulfate and sodium chloride solutions, uniaxial compression test and ultrasonic test were performed. Test results show that the relative dynamic elastic modulus, the mass variation, and the compressive strength of cement mortar increase first, and then decrease with increasing erosion time in sodium sulfate and sodium chloride solutions. The relative dynamic elastic moduli and the compressive strengths of cement mortars with water/cement ratios of 0.55 and 0.65 in sodium sulfate solution are lower than those in sodium chloride solution with the same concentration at the 420th day of immersion. The compressive strength of cement mortar with water/cement ratio of 0.65 is more sensitive to strain rate than that with water/cement ratio of 0.55. In addition, the strain-rate sensitivity of compressive strength of cement mortar will increase under attacks of sodium sulfate or sodium chloride solution.

  10. Effect of kaolin treatment temperature on mortar chloride permeability

    Directory of Open Access Journals (Sweden)

    Puertas, F.

    2007-03-01

    Full Text Available The present paper discusses the results of chloride resistance tests conducted on ordinary Portland cement (OPC mortars containing a Colombian kaolin pre-treated at temperatures of from 600 to 800 ºC. The resulting metakaolin (MK was added to OPC mortar mixes in proportions of 10 and 20% by cement weight. The mortars were compared for physical and chemical properties, including capillary absorption, chloride permeability and pore microstructure as assessed by mercury porosimetry. The best performance was recorded for the samples containing 20% of the material treated at 800 ºC.En el presente trabajo se incluyen los resultados de la resistencia a la penetración de cloruros de morteros de Cemento Portland Ordinario (OPC adicionados con un caolín colombiano sometido a tratamiento térmico en un rango de temperaturas entre 600 y 800 °C. Los productos del tratamiento térmico, metacaolín (MK, son incorporados en mezclas de morteros de OPC en proporciones del 10 y 20% en relación al peso del cemento. Se comparan sus características físico-químicas, entre las cuales se incluye la microestructura de poros evaluada por la técnica de porosimetría de mercurio, con la absorción capilar y la permeabilidad a cloruros. Se concluye que las muestras adicionadas con un 20% del material tratado térmicamente a 800 °C presentan el mejor desempeño en sus propiedades finales.

  11. Thermographic measurement of the effect of humidity in mortar porosity

    Science.gov (United States)

    Poblete, A.; Acebes Pascual, M.

    2007-01-01

    The objective of this analysis is to examine the influence of the moisture in the porosity measurement by means of thermal non-destructive test and ultrasound techniques. It is possible to determine the concrete durability by the calculation of its porosity. Porosity is determined in an indirect way, measuring mortar diffusivity by means of active thermography. Using ultrasound techniques, the porosity is related with the ultrasonic propagation of velocity. The diffusivity has been calculated using the W.J. Parker equation. In the ultrasound technique, using the pulse transmission method, ultrasonic propagation velocity was measured as a function of the water content. The conclusions express the correlation between both methods.

  12. Measurement of mortar permittivity during setting using a coplanar waveguide

    International Nuclear Information System (INIS)

    A sensor based on a coplanar waveguide structure was designed to perform non-destructive tests for material characterization in which the measurement can be done only on one side of the sample. The measurements were compared with the impedance of a capacitor filled with the same material. The permittivity and insertion loss of the sensor showed valuable information about the setting process of a mortar slab during the first 28 days of the hardening process, and a good correlation between both measurements was obtained, so the proposed setup can be useful for structural surveillance and moisture detection in civil structures

  13. Innovative technologies and materials for stone and mortar conservation

    Czech Academy of Sciences Publication Activity Database

    Drdácký, Miloš; Slížková, Zuzana

    Vol. 2. Sarajevo: CICOPBH, 2015 - (Popovac, M.; Idrizbegović-Zgonić, A.; Klarić, S.; Rustempašić, N.; Čausević, A.), s. 181-192 ISBN N. ISSN 2232-965X. [International conference The importance of place /3./. Sarajevo (BA), 21.10.2015-24.10.2015] R&D Projects: GA ČR(CZ) GBP105/12/G059 Institutional support: RVO:68378297 Keywords : stone conservation * mortar conservation * architectural heritage Subject RIV: AL - Art, Architecture, Cultural Heritage

  14. Performance of fly ash-based geopolymer mortar

    OpenAIRE

    Abdollahnejad, Zahra; Félix, T.; Torgal, Fernando Pacheco; Aguiar, J. L. Barroso de

    2015-01-01

    This study has investigated the joint effect of several mix parameters on the properties of foam geopolymers. The mix parameters analysed through a laboratory experiment of 54 different mortar mixes were, sodium silicate/sodium hydroxide mass ratio (2.5, 3.5, 4.5), activator/binder mass ratio (0.6, 0.8, 1.0), chemical foaming agent type (hydrogen peroxide (H2O2) and sodium perborate (NaBO3)) and foaming agent mass ratio content (1%, 2%, 3%). Properties, SEM and FTIR analysis and c...

  15. Chemical analysis of historic lime mortars: role of sample preparation

    Czech Academy of Sciences Publication Activity Database

    Ševčík, Radek; Šašek, Petr; Pérez-Estébanez, Marta; Viani, Alberto

    Zürich: Trans Tech Publications, 2015 - (Dvořák, K.; Gazdič, D.; Petránek, V.; Hájková, I.; Magrla, R.), s. 17-20 ISBN 978-3-03835-452-9. ISSN 1662-8985. [International Conference Binders and Materials (2nd ICBM) /2./. Brno (CZ), 04.12.2014] R&D Projects: GA MŠk(CZ) LO1219; GA ČR(CZ) GP14-20374P Institutional support: RVO:68378297 Keywords : lime * mortars * calcite * acid digestion * Rietveld method Subject RIV: AL - Art, Architecture, Cultural Heritage

  16. Incorporation of the Spinning Wastes in Cement and Mortars

    International Nuclear Information System (INIS)

    The study falls within the scope of the general problem of management of accumulated solid cellulose based wastes originating from textile industry especially those coming from the spinning process. The present investigation aims at studying the wet oxidative degradation technique as a method for treating cellulose-based wastes generated by the textile spinning industries. The resulting treated wastes were incorporated into cement or mortar. The mechanical integrity and the weight change of the final products were evaluated at the end of setting and hardening

  17. REVIEW OF MECHANISTIC UNDERSTANDING AND MODELING AND UNCERTAINTY ANALYSIS METHODS FOR PREDICTING CEMENTITIOUS BARRIER PERFORMANCE

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C.; Kosson, D.

    2009-11-30

    Cementitious barriers for nuclear applications are one of the primary controls for preventing or limiting radionuclide release into the environment. At the present time, performance and risk assessments do not fully incorporate the effectiveness of engineered barriers because the processes that influence performance are coupled and complicated. Better understanding the behavior of cementitious barriers is necessary to evaluate and improve the design of materials and structures used for radioactive waste containment, life extension of current nuclear facilities, and design of future nuclear facilities, including those needed for nuclear fuel storage and processing, nuclear power production and waste management. The focus of the Cementitious Barriers Partnership (CBP) literature review is to document the current level of knowledge with respect to: (1) mechanisms and processes that directly influence the performance of cementitious materials (2) methodologies for modeling the performance of these mechanisms and processes and (3) approaches to addressing and quantifying uncertainties associated with performance predictions. This will serve as an important reference document for the professional community responsible for the design and performance assessment of cementitious materials in nuclear applications. This review also provides a multi-disciplinary foundation for identification, research, development and demonstration of improvements in conceptual understanding, measurements and performance modeling that would be lead to significant reductions in the uncertainties and improved confidence in the estimating the long-term performance of cementitious materials in nuclear applications. This report identifies: (1) technology gaps that may be filled by the CBP project and also (2) information and computational methods that are in currently being applied in related fields but have not yet been incorporated into performance assessments of cementitious barriers. The various

  18. DNA repair

    International Nuclear Information System (INIS)

    In this chapter a series of DNA repair pathways are discussed which are available to the cell to cope with the problem of DNA damaged by chemical or physical agents. In the case of microorganisms our knowledge about the precise mechanism of each DNA repair pathway and the regulation of it has been improved considerably when mutants deficient in these repair mechanisms became available. In the case of mammalian cells in culture, until recently there were very little repair deficient mutants available, because in almost all mammalian cells in culture at least the diploid number of chromosomes is present. Therefore the frequency of repair deficient mutants in such populations is very low. Nevertheless because replica plating techniques are improving some mutants from Chinese hamsters ovary cells and L5178Y mouse lymphoma cells are now available. In the case of human cells, cultures obtained from patients with certain genetic diseases are available. A number of cells appear to be sensitive to some chemical or physical mutagens. These include cells from patients suffering from xeroderma pigmentosum, Ataxia telangiectasia, Fanconi's anemia, Cockayne's syndrome. However, only in the case of xeroderma pigmentosum cells, has the sensitivity to ultraviolet light been clearly correlated with a deficiency in excision repair of pyrimidine dimers. Furthermore the work with strains obtained from biopsies from man is difficult because these cells generally have low cloning efficiencies and also have a limited lifespan in vitro. It is therefore very important that more repair deficient mutants will become available from established cell lines from human or animal origin

  19. CEMENTITIOUS GROUT FOR CLOSING SRS HIGH LEVEL WASTE TANKS - #12315

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C.; Burns, H.; Stefanko, D.

    2012-01-10

    In 1997, the first two United States Department of Energy (US DOE) high level waste tanks (Tanks 17-F and 20-F: Type IV, single shell tanks) were taken out of service (permanently closed) at the Savannah River Site (SRS). In 2012, the DOE plans to remove from service two additional Savannah River Site (SRS) Type IV high-level waste tanks, Tanks 18-F and 19-F. These tanks were constructed in the late 1950's and received low-heat waste and do not contain cooling coils. Operational closure of Tanks 18-F and 19-F is intended to be consistent with the applicable requirements of the Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and will be performed in accordance with South Carolina Department of Health and Environmental Control (SCDHEC). The closure will physically stabilize two 4.92E+04 cubic meter (1.3 E+06 gallon) carbon steel tanks and isolate and stabilize any residual contaminants left in the tanks. The closure will also fill, physically stabilize and isolate ancillary equipment abandoned in the tanks. A Performance Assessment (PA) has been developed to assess the long-term fate and transport of residual contamination in the environment resulting from the operational closure of the F-Area Tank Farm (FTF) waste tanks. Next generation flowable, zero-bleed cementitious grouts were designed, tested, and specified for closing Tanks 18-F and 19-F and for filling the abandoned equipment. Fill requirements were developed for both the tank and equipment grouts. All grout formulations were required to be alkaline with a pH of 12.4 and chemically reduction potential (Eh) of -200 to -400 to stabilize selected potential contaminants of concern. This was achieved by including Portland cement and Grade 100 slag in the mixes, respectively. Ingredients and proportions of cementitious reagents were selected and adjusted, respectively, to support the mass placement strategy developed by

  20. Development and Performance Evaluation of Very High Early Strength Geopolymer for Rapid Road Repair

    OpenAIRE

    Pichai Taneerananon; Woraphot Prachasaree; Danupon Tonnayopas; Abideng Hawa

    2013-01-01

    High early strength is the most important property of pavement repair materials to allow quick reopening to traffic. With this in mind, we have experimentally investigated geopolymers using low cost raw materials available in Thailand. The geopolymer mortar was metakaolin (MK), mixed with parawood ash (PWA, rubberwood ash) or oil palm ash (OPA) as binder agent. Rubberwood is often used as raw material for biomass power plants in Thailand, especially at latex glove factories and seafood factor...

  1. Coupling nonlinear Stokes and Darcy flow using mortar finite elements

    KAUST Repository

    Ervin, Vincent J.

    2011-11-01

    We study a system composed of a nonlinear Stokes flow in one subdomain coupled with a nonlinear porous medium flow in another subdomain. Special attention is paid to the mathematical consequence of the shear-dependent fluid viscosity for the Stokes flow and the velocity-dependent effective viscosity for the Darcy flow. Motivated by the physical setting, we consider the case where only flow rates are specified on the inflow and outflow boundaries in both subdomains. We recast the coupled Stokes-Darcy system as a reduced matching problem on the interface using a mortar space approach. We prove a number of properties of the nonlinear interface operator associated with the reduced problem, which directly yield the existence, uniqueness and regularity of a variational solution to the system. We further propose and analyze a numerical algorithm based on mortar finite elements for the interface problem and conforming finite elements for the subdomain problems. Optimal a priori error estimates are established for the interface and subdomain problems, and a number of compatibility conditions for the finite element spaces used are discussed. Numerical simulations are presented to illustrate the algorithm and to compare two treatments of the defective boundary conditions. © 2010 Published by Elsevier B.V. on behalf of IMACS.

  2. Differentiating seawater and groundwater sulfate attack in Portland cement mortars

    International Nuclear Information System (INIS)

    The study reported in this article deals with understanding the physical, chemical and microstructural differences in sulfate attack from seawater and groundwater. Portland cement mortars were completely immersed in solutions of seawater and groundwater. Physical properties such as length, mass, and compressive strength were monitored periodically. Thermal analysis was used to study the relative amounts of phases such as ettringite, gypsum, and calcium hydroxide, and microstructural studies were conducted by scanning electron microscopy. Portland cement mortars performed better in seawater solution compared to groundwater solution. The difference in performance could be attributed to the reduction in the quantity of the expansive attack products (gypsum and ettringite). The high Cl concentration of seawater could have played an important role by binding the C3A to form chloroaluminate compounds, such as Friedel's salt (detected in the microstructural studies), and also by lowering the expansive potential of ettringite. Furthermore, the thicker layer of brucite forming on the specimens in seawater could have afforded better protection against ingress of the solution than in groundwater

  3. Nano-modification to improve the ductility of cementitious composites

    International Nuclear Information System (INIS)

    Effect of nano-sized mineral additions on ductility of engineered cementitious composites (ECC) containing high volumes of fly ash was investigated at different hydration degrees. Various properties of ECC mixtures with different mineral additions were compared in terms of microstructural properties of matrix, fiber-matrix interface, and fiber surface to assess improvements in ductility. Microstructural characterization was made by measuring pore size distributions through mercury intrusion porosimetry (MIP). Hydration characteristics were assessed using thermogravimetric analysis/differential thermal analysis (TGA/DTA), and fiber-matrix interface and fiber surface characteristics were assessed using scanning electron microscopy (SEM) through a period of 90 days. Moreover, compressive and flexural strength developments were monitored for the same period. Test results confirmed that mineral additions could significantly improve both flexural strength and ductility of ECC, especially at early ages. Cheaper Nano-CaCO3 was more effective compared to nano-silica. However, the crystal structure of CaCO3 played a very important role in the range of expected improvements

  4. Triboluminesence multifunctional cementitious composites with in situ damage sensing capability

    Science.gov (United States)

    Olawale, David O.; Dickens, Tarik; Uddin, Mohammed J.; Okoli, Okenwa O.

    2012-04-01

    Structural health monitoring of civil infrastructure systems like concrete bridges and dams has become critical because of the aging and overloading of these CIS. Most of the available SHM methods are not in-situ and can be very expensive. The triboluminescence multifunctional cementitious composites (TMCC) have in-built crack detection mechanism that can enable bridge engineers to monitor and detect abnormal crack formation in concrete structures so that timely corrective action can be taken to prevent costly or catastrophic failures. This article reports the fabrication process and test result of the flexural characterization of the TMCC. Accelerated durability test indicated that the 0.5 ZnS:Mn/Epoxy weight fraction ITOF sensor configuration to be more desirable in terms of durability. The alkaline environment at the highest temperature investigated (45 °C) resulted in significant reduction in the mean glass transition and storage moduli of the tested ITOF thin films. Further work is ongoing to correlate the TL response of the TMCC with damage, particularly crack opening.

  5. Uniaxial Compressive Properties of Ultra High Toughness Cementitious Composite

    Institute of Scientific and Technical Information of China (English)

    CAI Xiangrong; XU Shilang

    2011-01-01

    Uniaxial compression tests were conducted to characterize the main compressive performance of ultra high toughness cementitious composite(UHTCC)in terms of strength and toughness and to obtain its stress-strain relationships.The compressive strength investigated ranges from 30 MPa to 60 MPa.Complete stress-strain curves were directly obtained,and the strength indexes,including uniaxial compressive strength,compressive strain at peak stress,elastic modulus and Poisson's ratio,were calculated.The comparisons between UHTCC and matrix were also carried out to understand the fiber effect on the compressive strength indexes.Three dimensionless toughness indexes were calculated,which either represent its relative improvement in energy absorption capacity because of fiber addition or provide an indication of its behavior relative to a rigid-plastic material.Moreover,two new toughness indexes,which were named as post-crack deformation energy and equivalent compressive strength,were proposed and calculated with the aim at linking up the compressive toughness of UHTCC with the existing design concept of concrete.The failure mode was also given.The study production provides material characteristics for the practical engineering application of UHTCC.

  6. Nano-modification to improve the ductility of cementitious composites

    Energy Technology Data Exchange (ETDEWEB)

    Yeşilmen, Seda [Department of Civil Engineering, Çankaya University, Ankara (Turkey); Al-Najjar, Yazin [Department of Civil Engineering, Gaziantep University, Gaziantep (Turkey); Balav, Mohammad Hatam [Department of Civil Engineering, Gazi University, Ankara (Turkey); Şahmaran, Mustafa, E-mail: sahmaran@gazi.edu.tr [Department of Civil Engineering, Gazi University, Ankara (Turkey); Yıldırım, Gürkan [Department of Civil Engineering, Gazi University, Ankara (Turkey); Lachemi, Mohamed [Department of Civil Engineering, Ryerson University, Toronto, ON (Canada)

    2015-10-15

    Effect of nano-sized mineral additions on ductility of engineered cementitious composites (ECC) containing high volumes of fly ash was investigated at different hydration degrees. Various properties of ECC mixtures with different mineral additions were compared in terms of microstructural properties of matrix, fiber-matrix interface, and fiber surface to assess improvements in ductility. Microstructural characterization was made by measuring pore size distributions through mercury intrusion porosimetry (MIP). Hydration characteristics were assessed using thermogravimetric analysis/differential thermal analysis (TGA/DTA), and fiber-matrix interface and fiber surface characteristics were assessed using scanning electron microscopy (SEM) through a period of 90 days. Moreover, compressive and flexural strength developments were monitored for the same period. Test results confirmed that mineral additions could significantly improve both flexural strength and ductility of ECC, especially at early ages. Cheaper Nano-CaCO{sub 3} was more effective compared to nano-silica. However, the crystal structure of CaCO{sub 3} played a very important role in the range of expected improvements.

  7. Chemical modeling of cementitious grout materials alteration in HLW repositories

    International Nuclear Information System (INIS)

    This paper reports on an investigation initiated into the nature of the chemical alteration of cementitious grout in HLW repository seals, and the implications for long-term seal performance. The equilibrium chemical reaction of two simplified portland cement-based grout models with natural Canadian Shield groundwater compositions was modeled with the computer codes PHREEQE and EQ3NR/EQ6. Increases in porosity and permeability of the grout resulting from dissolution of grout phases and precipitation of secondary phases were estimated. Two bounding hydrologic scenarios were evaluated, one approximating a high gradient, high flow regime, the other a low-gradient, sluggish flow regime. Seal longevity depends in part upon the amount of groundwater coming into intimate contact with, and dissolving, the grout per unit time. Results of the analyses indicate that, given the assumptions and simplifications inherent in the models, acceptable seal performance (i.e., acceptable increases in hydraulic conductivity of the seals) may be expected for at least thousands of years in the worst cases analyzed, and possibly much longer

  8. Analysis on Factors Affecting the Self-Repair Capability of SMA Wire Concrete Beam

    Directory of Open Access Journals (Sweden)

    Li Sun

    2013-01-01

    Full Text Available Crack expansion of concrete is the initial damage stage of structures, which may cause greater damage to structures subject to long-term loads or under extreme conditions. In recent years, the application of intelligent materials to crack self-repair has become a hotspot among researchers. In order to study the influence of factors on the self-repair capability of shape memory alloy (SMA wire concrete beam, both theoretical and experimental methods were employed for analysis. For the convenience of experiment, composite materials (epoxy cement mortar and silicone polymer clay instead of concrete were used. The SMA wires were externally installed on and internally embedded in epoxy resin cement mortar beams and silicone polymer clay beams. Comparison of crack repair situation between two installation methods turns out that both methods possess their own advantages and disadvantages and should be employed according to the actual situation. The influence of unbonded length on the self-repair capability of embedded type SMA wire beams and the necessary minimum unbonded length to achieve self-repair function were studied. The results state clearly that the longer the unbonded length is, the better the crack repair situation is.

  9. ALKALI-ACTIVATED CEMENT MORTARS CONTAINING RECYCLED CLAY-BASED CONSTRUCTION AND DEMOLITION WASTE

    Directory of Open Access Journals (Sweden)

    F. Puertas

    2015-09-01

    Full Text Available The use of clay-based waste as an aggregate for concrete production is an amply studied procedure. Nonetheless, research on the use of this recycled aggregate to prepare alkaline cement mortars and concretes has yet to be forthcoming. The present study aimed to determine: the behaviour of this waste as a pozzolan in OPC systems, the mechanical strength in OPC, alkali-activated slag (AAS and fly ash (AAFA mortars and the effect of partial replacement of the slag and ash themselves with ground fractions of the waste. The pozzolanic behaviour of clay-based waste was confirmed. Replacing up to 20 % of siliceous aggregate with waste aggregate in OPC mortars induced a decline in 7 day strength (around 23 wt. %. The behaviour of waste aggregate in AAMs mortars, in turn, was observed to depend on the nature of the aluminosilicate and the replacement ratio used. When 20 % of siliceous aggregate was replaced by waste aggregate in AAS mortars, the 7 day strength values remained the same (40 MPa. In AAFA mortars, waste was found to effectively replace both the fly ash and the aggregate. The highest strength for AAFA mortars was observed when they were prepared with both a 50 % replacement ratio for the ash and a 20 % ratio for the aggregate.

  10. Characterization of historic lime mortars by neutron scattering and mercury porosimetry

    International Nuclear Information System (INIS)

    Complete text of publication follows. Lime mortars were commonly used in building from ancient Greek times through to the beginning of the nineteenth century [1]. In the past few years, the increased interest in conservation and restoration of historic monuments requires a better knowledge of the structure and composition of lime mortars resulting from the various additives, as well as the preparation technique each time used. Lime mortars from ancient Greek monuments have been dated by using the radiocarbon method [2]. Furthermore, a wide selection of lime mortars from known historic periods and monuments in Greece has been examined by mercury porosimetry. It was found that their structure depends on the utilization of the monument which come from. In specific, lime mortars coming from residences have more or less the same structure, whereas the preparation technique differs for lime mortars coming from tombs and walls. The weathering effects on the porous system of the mortars are studied by neutron scattering. (author) [1] Brown, P.W., and Clifton, J.R., 'Air pollution and conservation', eds. J. Roswall and S. Aleby, 225 (1988), Elsevier, Amsterdam.; [2] N. Zouridakis, J.F. Sliege, A. Person et al., Archaeometry, 60 (1987) 29

  11. Resistance of biofilm-covered mortars to microbiologically influenced deterioration simulated by sulfuric acid exposure

    International Nuclear Information System (INIS)

    Following the reported success of biofilm applications on metal surfaces to inhibit microbiologically influenced corrosion, effectiveness and sustainability of E. coli DH5α biofilm on mortar surface to prevent microbiologically influenced concrete deterioration (MICD) are investigated. Experiments simulating microbial attack were carried out by exposing incrementally biofilm-covered mortar specimens to sulfuric acid solutions with pH ranging from 3 to 6. Results showed that calcium concentration in control reactors without biofilm was 23–47% higher than the reactors with biofilm-covered mortar. Formation of amorphous silica gel as an indication of early stages of acid attack was observed only on the control mortar specimens without biofilm. During acidification, the biofilm continued to grow and its thickness almost doubled from ∼ 30 μm before acidification to ∼ 60 μm after acidification. These results demonstrated that E. coli DH5α biofilm was able to provide a protective and sustainable barrier on mortar surfaces against medium to strong sulfuric acid attack. -- Highlights: •Effectiveness of E.coli DH5α biofilm to prevent MICD was studied. •Conditions that lead to MICD were simulated by chemical acidification. •Biofilm-covered mortar specimens were exposed to sulfuric acid solutions. •The presence of biofilm helped reduce the chemically-induced mortar deterioration. •Biofilm remained alive and continued to grow during the acidification process

  12. Compression Sensibility of Magnetic-concentrated Fly Ash Mortar under Uniaxial Loading

    Institute of Scientific and Technical Information of China (English)

    JIA Xingwen; ZHANG Yajie; QIAN Jueshi

    2012-01-01

    The electrical conductivity,compression sensibility,workability and cost are factors that affect the application of conductive smart materials in civil structures.Consequently,the resistance and compression sensibility of magnetic-concentrated fly ash (MCFA) mortar were investigated using two electrode method,and the difference of compression sensibility between MCFA mortar and carbon fiber reinforced cement (CFRC)under uniaxial loading was studied.Factors affecting the compression sensibility of MCFA mortar,such as MCFA content,loading rate and stress cycles,were analyzed.Results show that fly ash with high content of Fe3O4 can be used to prepare conductive mortar since Fe3O4 is a kind of nonstoichiometric oxide and usually acts as semiconductor.MCFA mortar exhibits the same electrical conductivity to that of CFRC when the content of MCFA is more than 40% by weight of sample.The compression sensibility of mortar is improved with the increase of MCFA content and loading rate.The compression sensibility of MCFA mortar is reversible with the circling of loading.Results show that the application of MCFA in concrete not only provides excellent performances of electrical-functionality and workability,but also reduces the cost of conductive concrete.

  13. Resistance of biofilm-covered mortars to microbiologically influenced deterioration simulated by sulfuric acid exposure

    Energy Technology Data Exchange (ETDEWEB)

    Soleimani, Sahar, E-mail: ssoleima@connect.carleton.ca; Isgor, O. Burkan, E-mail: burkan_isgor@carleton.ca; Ormeci, Banu, E-mail: banu_ormeci@carleton.ca

    2013-11-15

    Following the reported success of biofilm applications on metal surfaces to inhibit microbiologically influenced corrosion, effectiveness and sustainability of E. coli DH5α biofilm on mortar surface to prevent microbiologically influenced concrete deterioration (MICD) are investigated. Experiments simulating microbial attack were carried out by exposing incrementally biofilm-covered mortar specimens to sulfuric acid solutions with pH ranging from 3 to 6. Results showed that calcium concentration in control reactors without biofilm was 23–47% higher than the reactors with biofilm-covered mortar. Formation of amorphous silica gel as an indication of early stages of acid attack was observed only on the control mortar specimens without biofilm. During acidification, the biofilm continued to grow and its thickness almost doubled from ∼ 30 μm before acidification to ∼ 60 μm after acidification. These results demonstrated that E. coli DH5α biofilm was able to provide a protective and sustainable barrier on mortar surfaces against medium to strong sulfuric acid attack. -- Highlights: •Effectiveness of E.coli DH5α biofilm to prevent MICD was studied. •Conditions that lead to MICD were simulated by chemical acidification. •Biofilm-covered mortar specimens were exposed to sulfuric acid solutions. •The presence of biofilm helped reduce the chemically-induced mortar deterioration. •Biofilm remained alive and continued to grow during the acidification process.

  14. AMS radiocarbon dating of mortar: The case study of the medieval UNESCO site of Modena

    Science.gov (United States)

    Carmine, Lubritto; Caroselli, Marta; Lugli, Stefano; Marzaioli, Fabio; Nonni, Sara; Marchetti Dori, S.; Terrasi, Filippo

    2015-10-01

    The carbon dioxide contributing to binder formation during the set of a lime mortar reflects the atmospheric 14C content at the time of construction of a building. For this reason, the 14C dating of mortars is used with increasing frequencies in archaeological and architectural research. Mortars, however, may also contain carbonaceous contaminants potentially affecting radiocarbon dating. The Centre for Isotopic Research on Cultural and Environmental heritage (CIRCE) of the Second University of Naples (SUN) has recently obtained some promising results in mortar radiocarbon dating thanks to the development of a procedure (i.e. CryoSoniC/Cryo2SoniC) aiming to eliminate exogenous C contamination that may occur in a mortar. The construction history of the UNESCO World Heritage Site of Modena (Italy) is still controversial and represents a challenging case study for the application of absolute dating methodologies for different reasons. From the point of view of 14C dating, for example, given the high percentage of carbonate aggregates composing these samples, Modena mortars represent an experimental test particularly indicative of exogenous carbon sources suppression ensuring methodology accuracy. In this paper several AMS Radiocarbon dates were carried out on lime lumps with the aim to: (i) verify procedure accuracy by a comparison of the results obtainable from lime lumps dated after different treatments (i.e. bulk lime lumps vs. CryoSoniC purified lime lumps); (ii) compare different building phases absolute chronology for the medieval UNESCO site of Modena, with that assumed by historical sources in order to assess preliminary the 14C dating feasibility for of the site. Historical temporal constraints and mortar clustering, based on petrography, have been applied to define a temporal framework of the analyzed structure. Moreover, a detailed petrographic characterization of mortars was used both as a preliminary tool for the choice of samples and to infer about the

  15. Hydrocele repair

    Science.gov (United States)

    ... small surgical cut in the fold of the groin, and then drains the fluid. The sac (hydrocele) holding the fluid may be removed. The surgeon strengthens the muscle wall with stitches. This is called a hernia repair. Sometimes the surgeon uses a laparoscope to do ...

  16. Motorcycle Repair.

    Science.gov (United States)

    Hein, Jim; Bundy, Mike

    This motorcycle repair curriculum guide contains the following ten areas of study: brake systems, clutches, constant mesh transmissions, final drives, suspension, mechanical starting mechanisms, electrical systems, fuel systems, lubrication systems, and overhead camshafts. Each area consists of one or more units of instruction. Each instructional…

  17. Bladder exstrophy repair

    Science.gov (United States)

    Bladder birth defect repair; Everted bladder repair; Exposed bladder repair; Repair of bladder exstrophy ... in boys and is often linked to other birth defects. Surgery is necessary to: Allow the child to ...

  18. Appraisal of a cementitious material for waste disposal: Neutron imaging studies of pore structure and sorptivity

    International Nuclear Information System (INIS)

    Cementitious materials are conventionally used in conditioning intermediate and low level radioactive waste. In this study a candidate cement-based wasteform has been investigated using neutron imaging to characterise the wasteform for disposal in a repository for radioactive materials. Imaging showed both the pore size distribution and the extent of the cracking that had occurred in the samples. The rate of the water penetration measured both by conventional sorptivity measurements and neutron imaging was greater than in pastes made from Ordinary Portland Cement. The ability of the cracks to distribute the water through the sample in a very short time was also evident. The study highlights the significant potential of neutron imaging in the investigation of cementitious materials. The technique has the advantage of visualising and measuring, non-destructively, material distribution within macroscopic samples and is particularly useful in defining movement of water through the cementitious materials.

  19. Carbonation kinetics in roman-like lime mortar

    Directory of Open Access Journals (Sweden)

    Sánchez-Moral, S.

    2004-09-01

    Full Text Available The kinetic parameterisation of lime mortar carbonation is a useful technique for understanding ancient building methods and the long-lived physical-chemical stability of roman monuments. Portlandite (Ca(OH2 binders harden in the air on contact with atmospheric CO2, producing CaCO3. Water evaporation and the presence of silicate aggregates have a three-fold effect: prompting the development of a pore system that permits CO2, self-diffusion, reducing shrinkage and cracking during drying and (possibly giving rise to subsequent pozzolanic reactions. The present survey involved air-hardening a series of roman-like lime mortars which differed in terms of: (i type of aggregate, volcanic tephra and arkose; (ii aggregate/binder ratio, 1:2 as used in the catacombs and 1:4 as found in standard roman construction and (iii temperature, the 17 ºC prevailing in underground environments and the 30 ºC typical of warm Mediterranean areas. The analyses that provided the most useful information were performed in a classic X-ray diffractometer adapted to accommodate an author-designed chamber in which temperature control was achieved by an internal refrigerant and a PID-governed electrical heater Additional data were obtained with DTA and environmental scanning electron microscopy (ESEM. The tests conducted on the Roman-like lime mortars manufactured for the experiment showed that the hardening temperature is a critical factor in the initial phases of carbonation. Calcite precipitation rates and total mineral precipitation increased with temperature, but fell very quickly as calcite precipitated. In theoretical calculations assuming an open reactor with continuous CO2, input, total calcitisation time was found to be 156 m in. at 30 ºC and 175 min. at 17 ºC, whilst in the mortars actually hardened in the experimental part of the study, calcitisation gradually blocked the flow or CO2, gas into the

  20. Self-healing of lime based mortars: Microscopy observations on case studies

    OpenAIRE

    Lubelli, B.; Nijland, T.G.; Hees, R.P.J. van

    2011-01-01

    Lime mortars have, up to a certain extent, a self-healing capacity which may contribute to their durability. Self-healing in lime mortars consists of a process of dissolution, transport and re-precipitation of calcium compounds to heal cracks and fissures. The spontaneous occurrence of self-healing in lime-based mortars is a well known phenomenon; to date, however, little research has been done on its occurrence in the practice. This study aims at gaining a better understanding of the self-he...

  1. INFLUENCE OF FLY ASH REPLACEMENT ON STRENGTH PROPERTIES OF CEMENT MORTAR

    OpenAIRE

    AMARNATH YERRAMALA; BHASKAR DESAI V; RAMA CHANDURDU C

    2012-01-01

    Strength properties of fly ash mortars were evaluated through laboratory investigations. OPC of 53 grade replaced with class F fly ash with 5 - 25 % in the increments of 5 %. The results shown that at early age at all fly ash replacements the strength decreased with respect to normal mortar. However, after 28 days and above themortars made with fly ash replacement up to 15% resulted higher strength than normal OPC mortar. Fly ash replacement of 20 and 25% always had lower strength than normal...

  2. Turbine repair process, repaired coating, and repaired turbine component

    Science.gov (United States)

    Das, Rupak; Delvaux, John McConnell; Garcia-Crespo, Andres Jose

    2015-11-03

    A turbine repair process, a repaired coating, and a repaired turbine component are disclosed. The turbine repair process includes providing a turbine component having a higher-pressure region and a lower-pressure region, introducing particles into the higher-pressure region, and at least partially repairing an opening between the higher-pressure region and the lower-pressure region with at least one of the particles to form a repaired turbine component. The repaired coating includes a silicon material, a ceramic matrix composite material, and a repaired region having the silicon material deposited on and surrounded by the ceramic matrix composite material. The repaired turbine component a ceramic matrix composite layer and a repaired region having silicon material deposited on and surrounded by the ceramic matrix composite material.

  3. Influence of electrified surface of cementitious materials on structure formation of hardened cement paste

    Science.gov (United States)

    Alekseev, A.; Gusakov, A.

    2015-01-01

    To provide high strength and durability of concrete it is necessary to study the influence of physical and chemical and mechanical principles of dispersed cementitious systems. The experimental bench was developed to study the influence of electrified surface of cementitious materials on structure formation of hardened cement paste. The test bench allows accelerating the processes of dissolution of cementing materials in water due to influence of electric discharge on their surface. Cement activation with high-voltage corona discharge when AC current is applied allows increasing the ultimate compressive strength of hardened cement paste by 46% at the age of one day and by 20% at the age of 28 days.

  4. Hydration reactions and ettringite formation in selected cementitious coal conversion by-products

    International Nuclear Information System (INIS)

    Cementitious reactions and ettringite formation, which occur when water is added to high-calcium fly ash, to many dry flue gas desulfurization solids, and to two of the residues from the emerging clean coal technologies, fluidized bed combustion and limestone injection multiphase burner, have been studied. The parameters varied included water to solid ratio and curing time. Crystalline reactants and products were monitored by X-ray powder diffraction. The amount of ettringite, the principal crystalline cementitious reaction product, was determined after three months of curing. In this paper results are discussed in terms of available Ca, Al and S in each by-product and w/s ratio

  5. Method for characterization of the rate of movement of an oxidation front in cementitious materials

    Energy Technology Data Exchange (ETDEWEB)

    Almond, Philip M.; Langton, Christine A.; Stefanko, David B.

    2016-03-01

    Disclosed are methods for determining the redox condition of cementitious materials. The methods are leaching methods that utilize a redox active transition metal indicator that is present in the cementitious material and exhibits variable solubility depending upon the oxidation state of the indicator. When the leaching process is carried out under anaerobic conditions, the presence or absence of the indicator in the leachate can be utilized to determine the redox condition of and location of the oxidation front in the material that has been subjected to the leaching process.

  6. Weathering Effect on 99Tc Leachability from Cementitious Waste Form

    International Nuclear Information System (INIS)

    The mass transfer of contaminants from the solid phase to the waste form pore water, and subsequently out of the solid waste form, is directly related to the number and size distribution of pores as well as the microstructure of the waste form. Because permeability and porosity are controlled by pore aperture size, pore volume, and pore distribution, it is important to have some indication of how these characteristics change in the waste form during weathering. Knowledge of changes in these key parameters can be used to develop predictive models that estimate diffusivity or permeability of radioactive contaminants can be used to develop predictive models that estimate diffusivity or permeability of radioactive contaminants from waste forms for long-term performance assessment. It is known that dissolution or precipitation of amorphous/crystalline phases within waste forms alters their pore structure and controls the transport of contaminants our of waste forms. One very important precipitate is calcite, which is formed as a result of carbonation reactions in cement and other high-alkalinity waste forms. Enhanced oxidation can also increase Tc leachability from the waste form. To account for these changes, weathering experiments were conducted in advance to increase our understating of the long-term Tc leachability, especially out of the cementitious waste form. Pore structure analysis was characterized using both N2 absorption analysis and XMT techniques, and the results show that cementitious waste form is a relatively highly-porous material compared to other waste forms studied in this task, Detailed characterization of Cast Stone chunks and monolith specimens indicate that carbonation reactions can change the Cast Stone pore structure, which in turn may correlate with Tc leachability. Short carbonation reaction times for the Cast Stone causes pore volume and surface area increases, while the average pore diameter decreases. Based on the changes in pore volumes

  7. Mechanisms of cementitious material deterioration in biogas digester.

    Science.gov (United States)

    Voegel, C; Bertron, A; Erable, B

    2016-11-15

    Digesters produce biogas from organic wastes through anaerobic digestion processes. These digesters, often made of concrete, suffer severe premature deterioration caused mainly by the presence of fermentative microorganisms producing metabolites that are aggressive towards cementitious materials. To clarify the degradation mechanisms in an anaerobic digestion medium, ordinary Portland cement paste specimens were immersed in the liquid fraction of a running, lab-scale digester for 4weeks. The anaerobic digestion medium was a mixture of a biowaste substrate and sludge from municipal wastewater treatment plant used as a source of anaerobic bacteria. The chemical characteristics of the anaerobic digestion liquid phase were monitored over time using a pH metre, high performance liquid chromatography (HPLC) and ion chromatography (HPIC). An initial critical period of low pH in the bioreactors was observed before the pH stabilized around 8. Acetic, propionic and butyric acids were produced during the digestion with a maximum total organic acid concentration of 50mmolL(-1). The maximum ammonium content of the liquid phase was 40mmolL(-1), which was about seven times the upper limit of the highly aggressive chemical environment class (XA3) as defined by the European standard for the specification of concrete design in chemically aggressive environments (EN 206). The changes in the mineralogical, microstructural and chemical characteristics of the cement pastes exposed to the solid and liquid phase of the digesters were analysed at the end of the immersion period by X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDS) and electron-probe micro-analysis (EPMA). A 700-μm thick altered layer was identified in the cement paste specimens. The main biodeterioration patterns in the bioreactors' solid/liquid phase were calcium leaching and carbonation of the cement matrix. PMID:27432729

  8. Bond strength of cementitious borehole plugs in welded tuff

    International Nuclear Information System (INIS)

    Axial loads on plugs or seals in an underground repository due to gas, water pressures and temperature changes induced subsequent to waste and plug emplacement lead to shear stresses at the plug/rock contact. Therefore, the bond between the plug and rock is a critical element for the design and effectiveness of plugs in boreholes, shafts or tunnels. This study includes a systematic investigation of the bond strength of cementitious borehole plugs in welded tuff. Analytical and numerical analysis of borehole plug-rock stress transfer mechanics is performed. The interface strength and deformation are studied as a function of Young's modulus ratio of plug and rock, plug length and rock cylinder outside-to-inside radius ratio. The tensile stresses in and near an axially loaded plug are analyzed. The frictional interface strength of an axially loaded borehole plug, the effect of axial stress and lateral external stress, and thermal effects are also analyzed. Implications for plug design are discussed. The main conclusion is a strong recommendation to design friction plugs in shafts, drifts, tunnels or boreholes with a minimum length to diameter ratio of four. Such a geometrical design will reduce tensile stresses in the plug and in the host rock to a level which should minimize the risk of long-term deterioration caused by excessive tensile stresses. Push-out tests have been used to determine the bond strength by applying an axial load to cement plugs emplaced in boreholes in welded tuff cylinders. A total of 130 push-out tests have been performed as a function of borehole size, plug length, temperature, and degree of saturation of the host tuff. The use of four different borehole radii enables evaluation of size effects. 119 refs., 42 figs., 20 tabs

  9. Long-Term Technetium Interactions With Reducing Cementitious Materials

    International Nuclear Information System (INIS)

    Technetium is among the key risk drivers at the Saltstone Facility. The way that it is immobilized in this cementitious waste form is by converting its highly mobile Tc(VII) form to a much less mobile Tc(IV) form through reduction by the cement's blast furnace slag. This report includes a review of published data and experimental results dealing with Tc leaching from Portland cement waste forms. The objectives for the literature study were to document previous reports of Tc interactions with slag-containing cementitious materials. The objectives for the laboratory study were to measure Tc-saltstone Kd values under reducing conditions. From the literature it was concluded: (1) Spectroscopic evidence showed that when Tc(IV) in a slag-cement was exposed to an oxidizing environment, it will convert to the more mobile Tc(VII) species within a short time frame, 2.5 years. (2) SRS saltstone will reduce Tc(VII) in the absence of NaS or sodium dithionite in a reducing atmosphere. (3) Only trace concentrations of atmospheric oxygen (30 to 60 ppm O2; Eh 120 mV) at the high pH levels of cementitious systems is required to maintain Tc as Tc(VII). (4) Experimental conditions must be responsible for wide variability of measured Kd values, such that they are either very low, ∼1 mL/g, or they are very high ∼1000 mL/g, suggesting that Tc(VII) or Tc(IV) dominate the systems. Much of this variability appears to be the result of experimental conditions, especially direct controls of oxygen contact with the sample. (5) A field study conducted at SRS in the 1980s indicated that a slag-saltstone immobilized Tc for 2.5 years. Below background concentrations of Tc leached out of the slag-containing saltstone, whereas Tc leached out of the slag-free saltstone at the rate of nitrate loss. One possible explanation for the immobilization of Tc in this study was that the slag-saltstone maintained reducing conditions within the core of the 55-gallon sample, whereas in the small-scale lab

  10. Cementitious Grout for Closing SRS High Level Waste Tanks - 12315

    International Nuclear Information System (INIS)

    In 1997, the first two United States Department of Energy (US DOE) high level waste tanks (Tanks 17-F and 20-F: Type IV, single shell tanks) were taken out of service (permanently closed) at the Savannah River Site (SRS). In 2012, the DOE plans to remove from service two additional Savannah River Site (SRS) Type IV high-level waste tanks, Tanks 18-F and 19-F. These tanks were constructed in the late 1950's and received low-heat waste and do not contain cooling coils. Operational closure of Tanks 18-F and 19-F is intended to be consistent with the applicable requirements of the Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and will be performed in accordance with South Carolina Department of Health and Environmental Control (SCDHEC). The closure will physically stabilize two 4.92E+04 cubic meter (1.3 E+06 gallon) carbon steel tanks and isolate and stabilize any residual contaminants left in the tanks. Ancillary equipment abandoned in the tanks will also be filled to the extent practical. A Performance Assessment (PA) has been developed to assess the long-term fate and transport of residual contamination in the environment resulting from the operational closure of the F-Area Tank Farm (FTF) waste tanks. Next generation flowable, zero-bleed cementitious grouts were designed, tested, and specified for closing Tanks 18-F and 19-F and for filling the abandoned equipment. Fill requirements were developed for both the tank and equipment grouts. All grout formulations were required to be alkaline with a pH of 12.4 and to be chemically reducing with a reduction potential (Eh) of -200 to -400. Grouts with this chemistry stabilize potential contaminants of concern. This was achieved by including Portland cement and Grade 100 slag in the mixes, respectively. Ingredients and proportions of cementitious reagents were selected and adjusted to support the mass placement strategy developed by

  11. DURABILITY OF MIXED MORTAR LINING CONTAINING DREGS-GRITS

    Directory of Open Access Journals (Sweden)

    B. P. Zanella

    2014-01-01

    Full Text Available The improper disposal of industrial waste and exploitation of natural resources has resulted in the scarcity of river sand and environmental degradation, such as river erosions and pollution. This study aimed to assess the durability of mixed mortar lining walls and ceilings, containing 0 (default, 10 and 20% of dregs-grits compounds-waste of the pulp industry-in substitution with river sand. This was done with tests that simulated both natural and artificial conditions: Direct solar incidence (testing ultraviolet radiation, attack by spraying solution (salt spray test, natural warming of the walls and ceilings incidence by indirect solar (thermal degradation and residential fires (thermogravimetric test, in compliance with both national and/or international standards. The grout containing dregs-grits compounds showed similarity to standard (0% for testing thermal degradability, thermogravimetric and ultraviolet radiation, but shows significantly less durability when exposed to salty environments.

  12. Mineralogical and microstructural studies of mortars from the bath complex of the Roman villa rustica near Mosnje (Slovenia)

    International Nuclear Information System (INIS)

    This study deals with the characterization of mortars collected from bath complex of the Roman villa rustica from an archeological site near Mosnje (Slovenia). The mortar layers of the mosaics, wall paintings and mortar floors were investigated. A special aggregate consisting of brick fragments was present in the mortars studied. The mineralogical and petrographic compositions of the mortars were determined by means of optical microscopy, X-ray powder diffraction and FTIR spectroscopy. Analysis of aggregate-binder interfaces using SEM-EDS revealed various types of reactivity rims. In order to assess the hydraulic characteristics of the mortars, the acid-soluble fractions were determined by ICP-OES. Furthermore, the results of Hg-porosimetry and gas sorption isotherms showed that mortars with a higher content of brick fragments particles exhibited a higher porosity and a greater BET surface area but a lower average pore diameter compared to mortars lacking this special aggregate. - Highlights: → Mineral and microstructural characterizations of brick-lime mortars. → Hydraulic character of mortars in Roman baths complex. → Reaction rims were observed around brick fragments and dolomitic grains. → Higher content of brick particles yielded a higher BET surface area. → Addition of brick particles increased porosity and diminished pore size diameter.

  13. Effect of crushed sand on mortar and concrete rheology

    Directory of Open Access Journals (Sweden)

    Cabrera, O. A.

    2011-09-01

    Full Text Available This article describes an experimental study conducted on fresh mortars and concretes made with crushed sand. The aim of this research was to assess the effect of aggregate particle shape and surface texture as well as dust content on mortar and concrete rheology. The experimental programme also addressed the impact of angular grains on chemical admixture performance and concrete bleeding. The findings showed that the use of crushed sand induces rheological behaviour that differs from the behaviour observed in natural sand and that superplasticisers can improve this behaviour considerably.

    En el presente trabajo se plantea un estudio experimental del estado fresco de morteros y hormigones con arenas de machaqueo, orientado a la evaluación de la incidencia de la forma y textura superficial de los granos del árido fino y del contenido de polvo sobre la reología de las mezclas. El programa experimental comprendió el estudio del estado fresco de hormigones con arenas con partículas angulares, la influencia de este tipo de partículas sobre la efectividad de los aditivos químicos y la evaluación de la influencia de las características físicas del árido fino sobre la exudación. Los resultados muestran que el empleo de arenas de machaqueo provoca un comportamiento reológico diferente al de hormigones con arenas naturales, y que el efecto de los aditivos superfluidificantes mejora notablemente este comportamiento.

  14. PROPERTIES OF LIGHTWEIGHT MASONRY MORTARS WITH HOLLOW GLASS MICROSPHERES FOR WINTER CONDITIONS

    Directory of Open Access Journals (Sweden)

    Semenov Vyacheslav Sergeevich

    2012-10-01

    reduction fillers (such as inflated pearlite, vermiculite etc. demonstrate low strength properties, as such fillers have a high water content. Hollow glass (or ceramic microspheres are known as efficient fillers for lightweight mortars. Multiple research undertakings contain information on the masonry mortar that has the following properties: average density of dry mortar - 450 kg/m3, thermal conductivity factor - 0.17 W/(m·°C, compressive strength at the age of 28 days - 3.2 MPa, water retention rate - over 90 %. The climatic conditions of Russia determine the need to perform masonry works at negative temperatures. Adding antifreeze admixtures is an easy and cheap method that guarantees hydration of the Portland-cement at negative temperatures. The subject of this research covers masonry mortars that have a 15 % hollow glass microsphere content and antifreeze admixtures. Contemporary antifreeze admixtures are multifunctional. Therefore, traditional antifreeze admixtures such as sodium chloride, calcium chloride, sodium nitrite, sodium nitrate, sodium formate, potash were used in the research. The per-cent content of antifreeze admixtures was calculated. The following properties of masonry mortars with a 15 % content of hollow glass microspheres and antifreeze admixtures were identified: average mortar and mortar mixture density, setting time, water retention, compressive and bending strength, and water absorption. Standard research methods were employed. Every mortar has an 8 cm mobility. The benchmark mixture has an average density of 1.085 kg/ m3, average cement stone density of 980 kg/m3, compressive strength at the age of 28 days - 19.8 MPa, water retention rate - 97 %, setting time - 4.5 hours. The attention was driven to the strength analysis of mortars with hollow glass microspheres and antifreeze admixtures at positive and negative temperatures. The authors proved that antifreeze admixtures demonstrated a negative influence on the strength and setting

  15. CASCADIC MULTIGRID METHOD FOR THE MORTAR ELEMENT METHOD FOR P1 NONCONFORMING ELEMENT

    Institute of Scientific and Technical Information of China (English)

    Chun-jia Bi; Dan-hui Hong

    2005-01-01

    In this paper, we consider the cascadic multigrid method for the mortar P1 nonconforming element which is used to solve the Poisson equation and prove that the cascadic conjugate gradient method is accurate with optimal complexity.

  16. Nitride Bonded Refractory Products and Their Matching Mortars GB/T 23293-2009

    Institute of Scientific and Technical Information of China (English)

    Zhang Xiaohui

    2009-01-01

    @@ 1 Scope This standard specifies the definition, classification, brand, shape, dimension, technical requirements, test methods, quality appraisal procedures, packing, marking, storage, transportation and quality certificate of nitride bonded refractory products and their matching mortars.

  17. Synthesis of Expansive Mortar Developed in Laboratory for Dismounting of Ornamental Rocks

    Energy Technology Data Exchange (ETDEWEB)

    Lucena D V [Graduate in Materials Engineering, UAEMa/ CCT/ UFCG, Campina Grande -P B (Brazil); Campos D B C [Graduate in Materials Engineering, UAEMa/ CCT/ UFCG, Campina Grande-PB (Brazil); Lira H L; Neves G A, E-mail: daniellymateriais@yahoo.com.br [Teacher Doctor UAEMa/ CCT/ UFCG, Campina Grande-PB (Brazil)

    2011-03-15

    The expansive mortar is constituted by a mixture of watery phase with an agent expander, when hydrated, presents volume increase and the generation of fictions in the rock due to generated pressure. The objective of this work is to synthecize expansive mortar that they present enough expansive pressure for the dismounting of granite and marble. They had been used as raw materials: carbonate of calcium, Portland cement and additives for control of the expansion. The formularizations had been synthecized on the basis of the chemical analysis of a mortar commercial and characterized by XRD, laser particle size measurements and evaluation of expansive pressure. All the developed formularizations had presented similar characteristics to the ones of the commercial mortar.

  18. Study of the fracture behavior of mortar and concretes with crushed rock or pebble aggregates

    Directory of Open Access Journals (Sweden)

    Sebastião Ribeiro

    2011-03-01

    Full Text Available The objective of this work was to compare the fracture energy of mortar and concretes produced with crushed rock and pebble aggregates using zero, 10, 20, 30 and 40% of aggregates mixed with standard mortar and applying the wedge splitting method to achieve stable crack propagation. The samples were cast in a special mold and cured for 28 days, after which they were subjected to crack propagation tests by the wedge splitting method to determine the fracture energies of the mortar and concrete. The concretes showed higher fracture energy than the mortar, and the concretes containing crushed rock showed higher resistance to crack propagation than all the compositions containing pebbles. The fracture energy varied from 38 to 55 J.m-2. A comparison of the number of aggregates that separated from the two concrete matrices with the highest fracture energies indicated that the concrete containing pebbles crumbled more easily and was therefore less resistant to crack propagation.

  19. Design of Inorganic Polymer Mortar from Ferricalsialic and Calsialic Slags for Indoor Humidity Control

    OpenAIRE

    Elie Kamseu; Isabella Lancellotti; Sglavo, Vincenzo M.; Luca Modolo; Cristina Leonelli

    2016-01-01

    Amorphous silica and alumina of metakaolin are used to adjust the bulk composition of black (BSS) and white (WSS) steel slag to prepare alkali-activated (AAS) mortars consolidated at room temperature. The mix-design also includes also the addition of semi-crystalline matrix of river sand to the metakaolin/steel powders. The results showed that high strength of the steel slag/metakaolin mortars can be achieved with the geopolymerization process which was particularly affected by the metallic i...

  20. Recycling Glass Cullet from Waste CRTs for the Production of High Strength Mortars

    OpenAIRE

    Stefano Maschio; Gabriele Tonello; Erika Furlani

    2013-01-01

    The present paper reports on the results of some experiments dealing with the recycling of mixed cathode ray tube (CRT) glass waste in the production of high-strength mortars. Waste CRT glass cullet was previously milled, and sieved, and the only fine fraction was added to the fresh mortar in order to replace part of the natural aggregate. The addition of superplasticizer was also investigated. All hydrated materials displayed high compressive strength after curing. Samples containing CRT mix...

  1. The colour potentials of SSA-containing mortar:the long version

    OpenAIRE

    Kappel, Annemette; Ottosen, Lisbeth M.; Kirkelund, Gunvor Marie; Bache, Anja Margrethe; Goltermann, Per

    2015-01-01

    This paper reports an experimental study of aesthetical qualities of mortar containing sewage sludgeash (SSA). SSA is the residue produced at water treatment plants where incineration of the sludge is applied in order to decrease volume and to prevent pathogens from spreading. Today SSA is with a few exceptions landfilled and thus, wasted.The purpose of the experiments was to examine the influence of SSA and how it affected the colour of mortar samples. SSA was ground in 6 different intervals...

  2. Effect of carbonation on the chloride diffusion of mortar specimens exposed to cyclic wetting and drying

    OpenAIRE

    Malheiro, Raphaele Lira Meireles Castro; Camões, Aires; Ferreira, Rui Miguel; Meira, Gibson; Amorim, M. T. Pessoa de

    2014-01-01

    Carbonation and chloride ingress are the two main causes of corrosion in reinforced concrete structures. Despite the combined action of these mechanisms being a reality, there is little research on the effect of carbonation on the chloride diffusion in concrete. This work intends to study the influence of carbonation on chloride diffusion of mortar specimens. Cubic mortar specimens were cast with 0.55 of water-cement ratio. After curing, the specimens were subjected to 56 days of wetting and ...

  3. Determination of Chlorinated Solvent Sorption by Porous Material—Application to Trichloroethene Vapor on Cement Mortar

    OpenAIRE

    Musielak, Marion; Brusseau, Mark L.; Marcoux, Manuel; Morrison, Candice; Quintard, Michel

    2014-01-01

    Experiments have been performed to investigate the sorption of trichloroethene (TCE) vapor by concrete material or, more specifically, the cement mortar component. Gas-flow experiments were conducted using columns packed with small pieces of cement mortar obtained from the grinding of typical concrete material. Transport and retardation of TCE at high vapor concentrations (500 mg L−1) was compared to that of a non-reactive gas tracer (Sulfur Hexafluoride, SF6). The results show a large magnit...

  4. Study on Strength of Innovative Mortar Synthesis with Epoxy Resin, Fly Ash and Quarry Dust

    Directory of Open Access Journals (Sweden)

    P. Sudheer

    2016-06-01

    Full Text Available Generally, mortar is a uniform combination of Fine aggregate and cement. In this study an innovative concept adopts to synthesis a hybrid mortar with Epoxy resin, Fly ash and quarry dust which are replacing the fine aggregate and cement. The alternative materials are preferably waste products such as quarry dust and fly ash in order to moderate the cost of mortar. The main objective of this work is to study the compressive strength of mortar cubes by various combinations of cement and fine aggregate replaced by Epoxy resin, fly ash, and quarry dust at the age of 7 days. The results of mortarmade with cement replaced with 20%, 25%, and 30% (w/w of Epoxy resin, and fine aggregate replaced by (0% QD - 100% FA (100% QD - 0% FA and (70% QD - 30% FA of quarry dust and fly ash were compared with conventional mortar cubes. It was observed that all mortar cubes made with Epoxy resin, fly ash, and quarry dust had found to have a compressive strength of more than 150% when compared to compressive strength with normal cement of OPC53 grade at the age of 7 days (Approx.35.5Mpa

  5. A Study on the Properties of Carbon Black Mortar Using Granulated Blast Furnace Slag and Polymer.

    Science.gov (United States)

    Jang, Hong-Seok; Jeon, Ui-Hyeon; So, Seung-Young

    2015-11-01

    White Portland Cement (WPC) and inorganic pigment have been used in colored concrete, but there are some physical problems such as increases in efflorescence, and poor workability and low economics. The aim of this study was to investigate the effects of GBFS and polymer (methyl cellulose) on the physical properties of carbon black mortar. For this purpose, a flow test, compressive strength test and color evaluation and was carried out on cement mortar mixed with polymer by changing the proportion of cement and ratio of GBFS. The results show that the addition of polymer influences significantly the color value efficiency in colored mortar. This is due to the reduction of overall amount of micro pore. This polymer films prevent the transport of soluble calcium towards the surface, and decreases efflorescence. And the flow of colored mortar was increased in proportion to the addition rate of the GBFS. In addition the strength of colored mortars with GBFS at the long-term aged (after 28 days) was higher than that of the general WPC mortar, although its strength was developed slowly at the early ages. PMID:26726652

  6. The Effect of Mortar Grade and Thickness on the Impact Resistance of Ferrocement Slab

    Science.gov (United States)

    Che Muda, Zakaria; Syamsir, Agusril; Nasharuddin Mustapha, Kamal; Sulleman, Sorefan; Beddu, Salmia; Thiruchelvam, Sivadass; Ismail, Firas B.; Usman, Fathoni; Liyana Mohd Kamal, Nur; Ashraful Alam, Md; Birima, Ahmed H.; Itam, Zarina; Zaroog, O. S.

    2016-03-01

    This paper investigate the effect of the thickness and mesh spacing on the impact of ferrocement for the concrete slab of 300mm × 300mm size reinforced subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.236 kg drop at height of 150 mm, 350mm, and 500mm has been used in this research work. The objective of this research is to study the relationship of impact resistance of ferrocement against the mortar grade and slab thickness. There is a good linear correlation between impact resistance of ferrocement against the mortar grade and the thickness of ferrocement slab. The first and ultimate crack impact resistance of mortar grade 43 (for 40 mm thick slab with mesh reinforcement) are 1.60 times and 1.53 times respectively against the mortar grade 17 slab (of same thickness with mesh reinforcement). The first and ultimate crack impact resistance for 40 mm thick slab (mortar grade 43 with mesh reinforcement) are 3.55 times and 4.49 times respectively against the 20 mm thick slab (of same mortar grade with mesh reinforcement).

  7. Utilization of ground waste seashells in cement mortars for masonry and plastering.

    Science.gov (United States)

    Lertwattanaruk, Pusit; Makul, Natt; Siripattarapravat, Chalothorn

    2012-11-30

    In this research, four types of waste seashells, including short-necked clam, green mussel, oyster, and cockle, were investigated experimentally to develop a cement product for masonry and plastering. The parameters studied included water demand, setting time, compressive strength, drying shrinkage and thermal conductivity of the mortars. These properties were compared with those of a control mortar that was made of a conventional Portland cement. The main parameter of this study was the proportion of ground seashells used as cement replacement (5%, 10%, 15%, or 20% by weight). Incorporation of ground seashells resulted in reduced water demand and extended setting times of the mortars, which are advantages for rendering and plastering in hot climates. All mortars containing ground seashells yielded adequate strength, less shrinkage with drying and lower thermal conductivity compared to the conventional cement. The results indicate that ground seashells can be applied as a cement replacement in mortar mixes and may improve the workability of rendering and plastering mortar. PMID:22841935

  8. Dynamic Mechanical Characterizations and Road Performances of Flame Retardant Asphalt Mortars and Concretes

    Institute of Scientific and Technical Information of China (English)

    QIN Xiantao; ZHU Siyue; LI Zuzhong; CHEN Shuanfa

    2015-01-01

    To research the dynamic mechanical properties and road performances of flame retardant asphalt mortars and mixtures, four different asphalt mortars/mixtures were prepared: a reference group and three asphalt mortars/mixtures containing composite lfame retardant materials (M-FRs) of different proportions. Temperature sweep, frequency sweep, repeated creep test, force ductility test and bending beam rheological test were carried out to research the dynamic mechanical properties of asphalt mortars containing M-FRs; wheel-tracking test, low-temperature bending test and freeze-thaw split test were used to study the road performances of asphalt mixtures containing M-FRs. The results show that high-temperature performances of the three lfame retardant asphalt mortars improve greatly, while low-temperature cracking resistances decline. Both high-temperature performances and water stabilities of asphalt mixtures containing M-FRs are quite good and exceed the speciifcation requirements. However, their low-temperature performances decline in different degrees. In summary, besides their good lfame retardancy, the lfame retardant asphalt mortars and mixtures also exhibit acceptable road performance.

  9. Mineralogical and textural characterization of mortars and plasters from the archaeological site of Barsinia, northern Jordan

    Directory of Open Access Journals (Sweden)

    Mustafa Mohammad AL-Naddaf

    2014-12-01

    Full Text Available Twelve mortar and plaster samples excavated in the archaeological site of Barsinia were mineralogically and petrographically examined by XRay Diffraction (XRD and Stereo and Polarized Light Microscopy, while the total carbonate content was measured using a DietrichFruhling Calcimeter. The physical properties of the samples, such as water uptake under atmospheric pressure and under vacuum, together with density and porosity, were measured. Only twelve samples were available for the purposes of this study: 8 plaster samples and 4 mortar samples. Eleven samples out of the total number of samples were mortars or plasters with lime binder and silica aggregate; calcite and quartz were identified in all of these samples. In most of the samples one or more pozzolanic components were detected; a hydraulic effect therefore exists in practically most of the studied mortars. Excluding the plasters taken from waterbearing constructions such as cisterns, and the mortar sample from the compact floor, the binder content is high; in general, the overall porosity of the studied samples is high. Porosity and petrographic investigation results suggest that the burning temperature of the limestone was low and/or the duration of the combustion was short; such preparation conditions produce a desirable quicklime. Owing to the significant compositional and textural differences between the samples that were reported, there is consequently no suitable general mortar that can be adopted for the restoration of the whole site.

  10. THERMALLY CONDUCTIVE CEMENTITIOUS GROUTS FOR GEOTHERMAL HEAT PUMPS. PROGRESS REPORT BY 1998

    Energy Technology Data Exchange (ETDEWEB)

    ALLAN,M.L.; PHILIPPACOPOULOS,A.J.

    1998-11-01

    Research commenced in FY 97 to determine the suitability of superplasticized cement-sand grouts for backfilling vertical boreholes used with geothermal heat pump (GHP) systems. The overall objectives were to develop, evaluate and demonstrate cementitious grouts that could reduce the required bore length and improve the performance of GHPs. This report summarizes the accomplishments in FY 98.

  11. Design of microcapsule system used for self-healing cementitious material

    NARCIS (Netherlands)

    Zhang, M.; Han, N.; Xing, F.; Schlangen, H.E.J.G.

    2013-01-01

    For a microcapsule based self-healing system in the cementitious material, a fundamental issue is to find and facilitate a suitable microcapsule system, concerning either the material selection or design and manufacture process. In this study, urea formaldehyde resin is used for the shell of microca

  12. Self-healing behavior of strain hardening cementitious composites incorporating local waste materials

    NARCIS (Netherlands)

    Qian, S.; Zhou, J.; Rooij, M.R. de; Schlangen, E.; Ye, G.; Breugel, K. van

    2009-01-01

    The self-healing behavior of a series of pre-cracked fiber reinforced strain hardening cementitious composites incorporating blast furnace slag (BFS) and limestone powder (LP) with relatively high water/binder ratio is investigated in this paper, focusing on the recovery of its deflection capacity.

  13. Glass science tutorial: Lecture No. 8, introduction cementitious systems for Low-Level Waste immobilization

    International Nuclear Information System (INIS)

    This report presents details about cementitious systems for low-level waste immobilization. Topics discussed include: composition and properties of portland cement; hydration properties; microstructure of concrete; pozzolans; slags; zeolites; transport properties; and geological aspects of long-term durability of concrete

  14. Predicting the Probability of Failure of Cementitious Sewer Pipes Using Stochastic Finite Element Method

    Directory of Open Access Journals (Sweden)

    Amir M. Alani

    2015-06-01

    Full Text Available In this paper, a stochastic finite element method (SFEM is employed to investigate the probability of failure of cementitious buried sewer pipes subjected to combined effect of corrosion and stresses. A non-linear time-dependant model is used to determine the extent of concrete corrosion. Using the SFEM, the effects of different random variables, including loads, pipe material, and corrosion on the remaining safe life of the cementitious sewer pipes are explored. A numerical example is presented to demonstrate the merit of the proposed SFEM in evaluating the effects of the contributing parameters upon the probability of failure of cementitious sewer pipes. The developed SFEM offers many advantages over traditional probabilistic techniques since it does not use any empirical equations in order to determine failure of pipes. The results of the SFEM can help the concerning industry (e.g., water companies to better plan their resources by providing accurate prediction for the remaining safe life of cementitious sewer pipes.

  15. Predicting the Probability of Failure of Cementitious Sewer Pipes Using Stochastic Finite Element Method.

    Science.gov (United States)

    Alani, Amir M; Faramarzi, Asaad

    2015-06-01

    In this paper, a stochastic finite element method (SFEM) is employed to investigate the probability of failure of cementitious buried sewer pipes subjected to combined effect of corrosion and stresses. A non-linear time-dependant model is used to determine the extent of concrete corrosion. Using the SFEM, the effects of different random variables, including loads, pipe material, and corrosion on the remaining safe life of the cementitious sewer pipes are explored. A numerical example is presented to demonstrate the merit of the proposed SFEM in evaluating the effects of the contributing parameters upon the probability of failure of cementitious sewer pipes. The developed SFEM offers many advantages over traditional probabilistic techniques since it does not use any empirical equations in order to determine failure of pipes. The results of the SFEM can help the concerning industry (e.g., water companies) to better plan their resources by providing accurate prediction for the remaining safe life of cementitious sewer pipes. PMID:26068092

  16. Research Progresses of New Type Alkali-activated Cementitious Material Catalyst

    Directory of Open Access Journals (Sweden)

    ZHANG Yao-Jun, YANG Meng-Yang, KANG Le, ZHANG Li, ZHANG Ke

    2016-03-01

    Full Text Available Alkali-activated solid aluminosilicate-based cementitious material is one of prospective research fields of advanced inorganic non-metallic materials. Its classification, preparation process, formation mechanism, and potential applications are reviewed in this paper. It is considered that its microstructure and chemical characteristics intensively depend on the raw materials and synthesis conditions. Geopolymers derive from alkali-activated metakaolin or fly ash with low calcium content, while the amorphous calcium silicate hydrate (C-S-H gels root in the chemical-activated solid wastes of granular blast furnace slag, steel slag and other solid aluminosilicate wastes with high calcium contents. Even though durability of alkali-activated cementitious materials as the building structure materials has been widely studied in the past decades, the intrinsic brittleness still restricts their applications in the field of civil and building engineering. Therefore, exploration of a new applied approach is by far the best option. In recent years, many researches report that the alkali-activated cementitious materials are used as novel precursors and catalysts for some kinds of heterogeneous reactions. The latest research progresses on alkali-activated cementitious material-based catalysts are discussed.

  17. Glass science tutorial: Lecture No. 8, introduction cementitious systems for Low-Level Waste immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Young, J.F.; Kirkpatrick, R.J.; Mason, T.O.; Brough, A.

    1995-07-01

    This report presents details about cementitious systems for low-level waste immobilization. Topics discussed include: composition and properties of portland cement; hydration properties; microstructure of concrete; pozzolans; slags; zeolites; transport properties; and geological aspects of long-term durability of concrete.

  18. Use of Artificial Neural Network for the Simulation of Radon Emission Concentration of Granulated Blast Furnace Slag Mortar.

    Science.gov (United States)

    Jang, Hong-Seok; Xing, Shuli; Lee, Malrey; Lee, Young-Keun; So, Seung-Young

    2016-05-01

    In this study, an artificial neural networks study was carried out to predict the quantity of radon of Granulated Blast Furnace Slag (GBFS) cement mortar. A data set of a laboratory work, in which a total of 3 mortars were produced, was utilized in the Artificial Neural Networks (ANNs) study. The mortar mixture parameters were three different GBFS ratios (0%, 20%, 40%). Measurement radon of moist cured specimens was measured at 3, 10, 30, 100, 365 days by sensing technology for continuous monitoring of indoor air quality (IAQ). ANN model is constructed, trained and tested using these data. The data used in the ANN model are arranged in a format of two input parameters that cover the cement, GBFS and age of samples and, an output parameter which is concentrations of radon emission of mortar. The results showed that ANN can be an alternative approach for the predicting the radon concentration of GBFS mortar using mortar ingredients as input parameters. PMID:27483913

  19. Evolution of 99Tc Species in Cementitious Nuclear Waste Form

    International Nuclear Information System (INIS)

    Technetium (Tc) is produced in large quantities as a fission product during the irradiation of 235U-enriched fuel for commercial power production and plutonium genesis for nuclear weapons. The most abundant isotope of Tc present in the wastes is 99Tc because of its high fission yield (∼6%) and long half-life (2.13x105 years). During the Cold War era, generation of fissile 239Pu for use in America's atomic weapons arsenal yielded nearly 1900 kg of 99Tc at the U.S. Department of Energy's (DOE) Hanford Site in southeastern Washington State. Most of this 99Tc is present in fuel reprocessing wastes temporarily stored in underground tanks awaiting retrieval and permanent disposal. After the wastes are retrieved from the storage tanks, the bulk of the high-level waste (HLW) and lowactivity waste (LAW) stream is scheduled to be converted into a borosilicate glass waste form that will be disposed of in a shallow burial facility called the Integrated Disposal Facility (IDF) at the Hanford Site. Even with careful engineering controls, volatilization of a fraction of Tc during the vitrification of both radioactive waste streams is expected. Although this volatilized Tc can be captured in melter off-gas scrubbers and returned to the melter, some of the Tc is expected to become part of the secondary waste stream from the vitrification process. The off-gas scrubbers downstream from the melters will generate a high pH, sodium-ammonium carbonate solution containing the volatilized Tc and other fugitive species. Effective and cost-efficient disposal of Tc found in the off-gas scrubber solution remains difficult. A cementitious waste form (Cast Stone) is one of the nuclear waste form candidates being considered to solidify the secondary radioactive liquid waste that will be generated by the operation of the waste treatment plant (WTP) at the Hanford Site. Because Tc leachability from the waste form is closely related with Tc speciation or oxidation state in both the simulant and

  20. Avrami's law based kinetic modeling of colonization of mortar surface by alga Klebsormidium flaccidum

    OpenAIRE

    Tran, Thu Hien; Govin, Alexandre; Guyonnet, René; Grosseau, Philippe; Lors, Christine; Damidot, Denis; Devès, Olivier; Ruot, Bertrand

    2013-01-01

    International audience The aim of this research was to modelize the colonization of mortar surface by green algae using Avrami's law. The resistance of mortars, with different intrinsic characteristics (porosity, roughness, carbonation state), to the biofouling was studied by means of an accelerated lab-scale test. A suspension of green alga Klebsormidium flaccidum, was performed to periodically sprinkle the mortar surfaces. The covered surface rate followed a sigmoidal type curve versus t...

  1. Application of encapsulated lightweight aggregate impregnated with sodium monofluorophosphate as a self-healing agent in blast furnace slag mortar

    OpenAIRE

    Sisomphon, K.; Copuroglu,O.; Fraaij, A.

    2011-01-01

    This paper studies the potential of using expanded clay lightweight aggregate impregnated with sodium monofluorophosphate (Na2FPO3) solution which is eventually encapsulated by a cement paste layer to produce a self-healing system in blast furnace slag cement mortars. It was found that the technique significantly improved the quality of the interfacial transition zone in mortars subjected to carbonation shrinkage. Consequently the frost salt scaling durability of blast furnace slag mortars wa...

  2. Carbon footprint of geopolymeric mortar: Study of the contribution of the alkaline activating solution and assessment of an alternative route

    OpenAIRE

    Mellado Romero, Ana María; CATALAN, C; Bouzón, N.; Borrachero Rosado, María Victoria; Monzó Balbuena, José Mª; Paya Bernabeu, Jorge Juan

    2014-01-01

    CO2 emissions associated with geopolymeric mortar prepared using spent fluid catalytic cracking catalyst (FCC) were compared to those calculated for plain ordinary Portland cement (OPC) mortar. Commercial waterglass used for preparing the alkaline activating solution for geopolymeric mortar was the main contributing component related to CO2 emission. An alternative route for formulating alkaline activating solution in the preparation of the geopolymeric binder was proposed: refluxing of rice ...

  3. Corrugated stainless steels embedded in mortar for 9 years: corrosion results of non-carbonated, chloride-contaminated samples

    OpenAIRE

    Bautista, A.; Paredes, E. C.; Velasco, F.; Álvarez, S. M.

    2015-01-01

    Mortar samples reinforced with 5 different corrugated stainless steels were tested for 9 years in 2 different conditions: partial immersion (PI) in 3.5% NaCl, and chloride addition to the mortar and exposure to high relative humidity (HRH). The monitoring during the exposures was carried out with corrosion potential (E-corr) and electrochemical impedance spectroscopy (EIS) measurements. A year before finishing (after 8 years of exposure), the reinforced mortar samples were anodically polarise...

  4. Relation between Modulus of Elasticity and Compressive Strength of Ultrahigh-Strength Mortar with Mixed Silicon Carbide as Fine Aggregate

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Ultrahigh-strength mortar mixed surface-oxidized silicon carbide as a fine aggregate was prepared by means of press-casting followed by curing in an autoclave. The relation between modulus of elasticity up to 111 GPa and compressive strength up to 360 MPa of mortar mixed silicon carbide was discussed and it was revealed that the contributions of the aggregate hardness and of the interfacial strength between the aggregate and the cement paste on the elasticity of mortar were imporant.

  5. On the Application of Inertial Microfluidics for the Size-Based Separation of Polydisperse Cementitious Particulates

    Science.gov (United States)

    Kumar, Aditya; Lewis, Peter; Balonis, Magdalena; Di Carlo, Dino; Sant, Gaurav

    2015-06-01

    The early-age performance of concrete is determined by the properties of the cementitious binder and the evolution of its chemical reactions. The chemical reactivity, and to some extent, the composition of cementitious particles can depend on particle size. Therefore, it is valuable to physically separate cementing minerals into well-defined size classes so that the influences of both particle size and composition on reaction progress can be studied without the confounding effects of a broad particle size distribution. However, conventional particle separation methods (e.g., density fractionation, wet sieving, field-flow extraction, ultrasonification-sedimentation) are time-consuming and cumbersome and result in poor particle yields and size-selectivity, thus, making them unsuitable for processing larger volumes of cementitious powders (on the order of grams). This study applies a novel inertial microfluidics (IMF) based procedure to separate cementitious powders on the basis of their size. Special attention is paid to optimizing operating variables to ensure that particles in a fluid streamline achieve unique equilibrium positions within the device. From such positions, particles can be retrieved as per their size using symmetrical outlet configurations with tuned fluidic resistances. The approach is critically assessed in terms of: (1) its ability to separate cementitious powders into narrow size bins, and therefore its feasibility as a fractionation procedure, and (2) quantitatively relating the operating parameters to the particle yield and size selectivity. The study establishes metrics for assessing the ability of IMF methods to classify minerals and other polydisperse particles on the basis of their size.

  6. uv photobiology: excision repair

    International Nuclear Information System (INIS)

    The following topics are discussed: steps in nucleotide excision; damage to DNA by uv-endonuclease; use of complementation to study DNA repair in Escherichia coli and mammalian cells; role of BUDR photolysis in excision repair, relation between DNA repair defect and human disease; base excision repair; and excision repair by removal of damaged region of a base in DNA without excision

  7. Material properties of hollow clay tile and existing mortar characterization study

    International Nuclear Information System (INIS)

    Several Buildings at the Department of Energy (DOE) Oak Ridge Y-12 Plant were constructed (circa 1950) using unreinforced hollow clay tile masonry walls, which act as shear walls to resist lateral forces. A comprehensive test program, managed by the Center for Natural Phenomena Engineering (CNPE) of Martin Marietta Energy Systems, Inc. (MMES), is under way to determine material properties of existing hollow clay tile walls that will be used to help determine the structural strength of those buildings. This paper presents the results of several types of material property tests of 4-in.- and 8-in.-thick hollow clay tiles. These tests include determination of weight, size, void area, net area and gross area, initial rate of absorption, absorption, modulus of rupture, splitting tensile strength, and compressive strength. The tests were performed on old, reclaimed tiles and new tiles. A total of 336 tiles were tested. The stress-strain relationship for 40 specimens was also obtained. All testing was performed in accordance with ASTM standards and procedures developed by CNPE. This paper also presents the results of an investigation of mortar removed from the existing walls. The mortar characterization study was performed by Testwell Craig Materials Consultants under subcontract to MMES. Petrographic and chemical investigations were conducted on 18 mortar samples removed from four buildings at the plant. The primary purpose of the investigations was to evaluate the properties of existing mortar and provide a similar specification for the mortar to be used for construction of test specimens and test walls for the test program. The study showed variability in the mortars among buildings and among different locations within a building; however, it was concluded that an average mortar mix conforming to ASTM type N proportioned by volume of Portland cement, hydrated lime, and Tennessee river sand would be used to conduct further laboratory studies of masonry assemblages

  8. Brain aneurysm repair

    Science.gov (United States)

    ... aneurysm repair; Dissecting aneurysm repair; Endovascular aneurysm repair - brain; Subarachnoid hemorrhage - aneurysm ... Your scalp, skull, and the coverings of the brain are opened. A metal clip is placed at ...

  9. Eye muscle repair - discharge

    Science.gov (United States)

    ... Lazy eye repair - discharge; Strabismus repair - discharge; Extraocular muscle surgery - discharge ... You or your child had eye muscle repair surgery to correct eye muscle ... term for crossed eyes is strabismus. Children most often ...

  10. Patch repair: compatibility issues

    OpenAIRE

    Garbacz, Andrzej; Courard, Luc; Bissonnette, Benoît; Głodkowska, W.

    2014-01-01

    Repair of any concrete structure results in formation of complex, at least two-component repair systems. Compatibility approach is treated as a basic requirement during selection of repair material. Recently, the understanding for compatibility requirements in repair systems approach is demonstrated in many papers. The aim of this paper is analyzing the compatibility between repair materials and concrete substrate in the case of patch repair. The compatibility issues were discussed in light o...

  11. Study on Overall Concept Planning of Terminal Correction Mortar Projectiles

    Institute of Scientific and Technical Information of China (English)

    XU Jin-xiang

    2008-01-01

    The system composition, the operational principle of terminal correction mortar projectiles (TCMP) and the concept planning design of TCMP are researched in this paper. An overall design and aerodynamic configuration layout for TCMP are made in this paper, and its aerodynamic coefficients are calculated by using computational fluid dynamics (CFD) software. Test results of TCMP simulated ballistic projectiles indicate the designed TCMP can satisfy the interior ballistic demand and has a fine flight stability. The drag coefficients identified from the radar velocity-time data are in accord with the CFD computed results. According to the exposure frequency of the ground laser designator, a four-quadrant impulse correction scheme and a high exposure frequency impulse correction scheme are brought. The latter can calculate the target azimuth angle by counting the times of the facula passing through one quadrant. Simulation results also show that the guidance precision of the velocity pursuit is higher than that of the body pursuit, and the detector axis is less circuitous. Researches on the typical trajectory indicate that the terminal impulse correction can improve the hit precision of TCMP remarkably.

  12. Mortar cohesión. The effect of additives

    Directory of Open Access Journals (Sweden)

    Castro, J. H.

    1975-12-01

    Full Text Available This study was concerned with the hydration of clinker compounds in the presence of different additives; it appeared that accelerating additives, such as calcium chloride and silicic acid, produce longer fibers of tobermorite, whereas inhibitors, such as sugar, produce shorter fibers of tobermorite. This same effect was observed in the hydration of anhydrite, in which large crystals of gypsum were produced in the presence of sodium sulphate. So the cohesion in mortars of cement and anhydrite is explained in terms of the role of fibers.Se estudia la hidratación del clínker en presencia de diferentes aditivos encontrándose que los aceleradores, como el cloruro cálcico y el ácido salicílico, producen tobermorita de fibra larga y los inhibidores, como el azúcar, tobermorita de fibra corta. Este mismo efecto se encuentra en la anhidrita, produciéndose cristales de yeso largo, en presencia del sulfato de sodio, y cristales cortos en ausencia del catalizador. La cohesión de un mortero depende luego del largo de sus fibras. Así la cohesión de los morteros de cemento y anhidrita se explican en función del rol de la fibra.

  13. Thaumasite-ettringite solid solutions in degraded mortars

    International Nuclear Information System (INIS)

    The thaumasite form of sulfate attack (TSA) has been observed in mortar prisms made from Portland-limestone cements after laboratory storage in 1.8% magnesium sulfate solution at 5 deg. C for 5 years. The prisms all showed evident signs of degradation, which increased with increasing limestone content. X-ray powder diffraction indicated that a solid solution was formed in all the prisms, which was based on the crystal structure of thaumasite, but extended towards the chemical composition of ettringite. The prism made from the cement with the highest level (35%) of limestone replacement gave the greatest amount of the thaumasite solid solution and had a composition close to the thaumasite end member, whereas those cements with lower (15%, 5% and 0%) levels of replacement gave reduced amounts of the solid solution and had greater lattice parameters. The solid solutions that have been observed are compared with those reported by Barnett et al. for synthetic thaumasite samples grown from sucrose solution

  14. The guard-mortars in the defence of Odessa (1941

    Directory of Open Access Journals (Sweden)

    Ovcharenko Nikolay Vasilyevich

    2013-11-01

    Full Text Available The author of the article analyzes the use and improvement of BM-8 and BM-13 Soviet land multiple launch rocket system. The author studied the fast tempo of evolution of reactive artillery of the Soviet Union in the years of the Great Patriotic War. The author cited history of the first battle using of reactive shells: RS-82 and RS-132 of “air-air” and “airland” on the Soviet Il-2 aircrafts and SB bombers; using RS-82 with I-16 aircrafts and with artillery-lorry “Komsomolets” during the defense of Odessa. The author investigated the secret see-transportation of the 48-th special force guards mortars to Odessa, the special ways for secret of new weapons; the technical-tactic characteristics of reactive weapons and battle activity 48-th force’s in the Odessa Defense Area. The article presents the analysis of the organization of the battle using of guardmortars force; sudden concentration strikes against enemy, which was preparing to attack. The author tells about reactive artillery support, fast chancing positions of reactive artillery, fire maneuvering on different sectors of the Odessa defense system, cooperation between reactive and other artillery.

  15. Effects of the restoration mortar on chalk stone buildings

    Science.gov (United States)

    Ion, R. M.; Teodorescu, S.; Ştirbescu, R. M.; Dulamă, I. D.; Şuică-Bunghez, I. R.; Bucurică, I. A.; Fierăscu, R. C.; Fierscu, I.; Ion, M. L.

    2016-06-01

    The monument buildings as components of cultural heritage are exposed to degradation of surfaces and chemical and mechanical degradation, often associated to soiling and irreversible deterioration of the building. In many conservative and restorative works, a cement-based mortar was used without knowing all the adverse effects of this material on the building. This paper deals with the study of the effects of natural cement used in restorative works in the particular case of the Basarabi-Murfatlar Churches Ensemble. Cement-based materials exposed to sulfate present in the chalk stone - gypsum (CaSO4.2H2O), can induce signs of deterioration, due to ettringite ([Ca3Al (OH)612H2O]2(SO4)32H2O) or thaumasite (Ca3[Si(OH)612H2O](CO3)SO4) formation. These phases contribute to strain within the material, inducing expansion, strength loss, spalling and severe degradation. Several combined techniques (XRD, EDXRF, ICP-AES, SEM, EDS, sulphates content, FT-IR and Raman analysis were carried out to put into evidence the effects of them on the building walls.

  16. Preparation of Cementitious Material Using Smelting Slag and Tailings and the Solidification and Leaching of Pb2+

    OpenAIRE

    Dan Zhang; Shiliu Shi; Chengbiao Wang; Xiaocong Yang; Lijie Guo; Shanshan Xue

    2015-01-01

    The composite cementitious materials were prepared with lead-zinc tailings, lead-zinc smelting slag, and cement clinker. The effect of material ratio on the mechanical properties, the phase analysis, and microstructures were investigated. The effect of the pH and stripping time on the leaching amount of lead ion was discussed. The results show that the additive amount of the tailings should be minimized for the cementitious materials meeting the strength requirements, controlled within 10%. T...

  17. Development and Demonstration of Material Properties Database and Software for the Simulation of Flow Properties in Cementitious Materials

    Energy Technology Data Exchange (ETDEWEB)

    Smith, F. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Flach, G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-03-30

    This report describes work performed by the Savannah River National Laboratory (SRNL) in fiscal year 2014 to develop a new Cementitious Barriers Project (CBP) software module designated as FLOExcel. FLOExcel incorporates a uniform database to capture material characterization data and a GoldSim model to define flow properties for both intact and fractured cementitious materials and estimate Darcy velocity based on specified hydraulic head gradient and matric tension. The software module includes hydraulic parameters for intact cementitious and granular materials in the database and a standalone GoldSim framework to manipulate the data. The database will be updated with new data as it comes available. The software module will later be integrated into the next release of the CBP Toolbox, Version 3.0. This report documents the development efforts for this software module. The FY14 activities described in this report focused on the following two items that form the FLOExcel package; 1) Development of a uniform database to capture CBP data for cementitious materials. In particular, the inclusion and use of hydraulic properties of the materials are emphasized; and 2) Development of algorithms and a GoldSim User Interface to calculate hydraulic flow properties of degraded and fractured cementitious materials. Hydraulic properties are required in a simulation of flow through cementitious materials such as Saltstone, waste tank fill grout, and concrete barriers. At SRNL these simulations have been performed using the PORFLOW code as part of Performance Assessments for salt waste disposal and waste tank closure.

  18. Acoustic Behavior of Subfloor Lightweight Mortars Containing Micronized Poly (Ethylene Vinyl Acetate (EVA

    Directory of Open Access Journals (Sweden)

    Luiza R. Brancher

    2016-01-01

    Full Text Available This paper aims to contribute to acoustical comfort in buildings by presenting a study about the polymer waste micronized poly (ethylene vinyl acetate (EVA to be used in mortars for impact sound insulation in subfloor systems. The evaluation method included physical, mechanical and morphological properties of the mortar developed with three distinct thicknesses designs (3, 5, and 7 cm with replacement percentage of the natural aggregate by 10%, 25%, and 50% EVA. Microscopy analysis showed the surface deposition of cement on EVA, with preservation of polymer porosity. The compressive creep test estimated long-term deformation, where the 10% EVA sample with a 7 cm thick mortar showed the lowest percentage deformation of its height. The impact noise test was performed with 50% EVA samples, reaching an impact sound insulation of 23 dB when the uncovered slab was compared with the 7 cm thick subfloor mortar. Polymer waste addition decreased the mortar compressive strength, and EVA displayed characteristics of an influential material to intensify other features of the composite.

  19. Chemical functionalization of ceramic tile surfaces by silane coupling agents: polymer modified mortar adhesion mechanism implications

    Directory of Open Access Journals (Sweden)

    Alexandra Ancelmo Piscitelli Mansur

    2008-09-01

    Full Text Available Adhesion between tiles and mortars are crucial to the stability of ceramic tile systems. From the chemical point of view, weak forces such as van der Waals forces and hydrophilic interactions are expected to be developed preferably at the tiles and polymer modified Portland cement mortar interface. The main goal of this paper was to use organosilanes as primers to modify ceramic tile hydrophilic properties to improve adhesion between ceramic tiles and polymer modified mortars. Glass tile surfaces were treated with several silane derivatives bearing specific functionalities. Contact angle measurements and Fourier Transform Infrared Spectroscopy (FTIR were used for evaluating the chemical changes on the tile surface. In addition, pull-off tests were conducted to assess the effect on adhesion properties between tile and poly(ethylene-co-vinyl acetate, EVA, modified mortar. The bond strength results have clearly shown the improvement of adherence at the tile-polymer modified mortar interface, reflecting the overall balance of silane, cement and polymer interactions.

  20. Use of waste brick as a partial replacement of cement in mortar

    International Nuclear Information System (INIS)

    The aim of this study is to investigate the use of waste brick as a partial replacement for cement in the production of cement mortar. Clinker was replaced by waste brick in different proportions (0%, 5%, 10%, 15% and 20%) by weight for cement. The physico-chemical properties of cement at anhydrous state and the hydrated state, thus the mechanical strengths (flexural and compressive strengths after 7, 28 and 90 days) for the mortar were studied. The microstructure of the mortar was investigated using scanning electron microscopy (SEM), the mineralogical composition (mineral phases) of the artificial pozzolan was investigated by the X-ray diffraction (XRD) and the particle size distributions was obtained from laser granulometry (LG) of cements powders used in this study. The results obtained show that the addition of artificial pozzolan improves the grinding time and setting times of the cement, thus the mechanical characteristics of mortar. A substitution of cement by 10% of waste brick increased mechanical strengths of mortar. The results of the investigation confirmed the potential use of this waste material to produce pozzolanic cement.

  1. Superplasticized Portland cement: Production and compressive strength of mortars and concrete

    Energy Technology Data Exchange (ETDEWEB)

    Bouzoubaa, N.; Zhang, M.H.; Malhotra, V.M. [Natural Resources Canada, Ottawa, Ontario (Canada)

    1998-12-01

    This paper deals with the effect of intergrinding different percentages of a naphthalene-based superplasticizer with Portland cement clinker and gypsum on the fineness of the product, and on the water requirement and the compressive strength of the mortars made with the superplasticized cement. The properties of the fresh and hardened concrete made with the superplasticized cements were also investigated. The results showed that the intergrinding of a given amount of a naphthalene-based superplasticizer with Portland clinker and gypsum reduced the grinding time required for obtaining the same Blaine fineness as that of the control Portland cement without the superplasticizer. The water requirement of the mortars made with the superplasticized cements was similar to that of the mortars made with the control Portland cements when the same amount of the superplasticizer was added at the mortar mixer; for a given grinding time and a Blaine fineness of {approximately}4500 cm{sup 2}/g, the mortars made with the superplasticized cement had higher compressive strength than those made with the control Portland cement. For a given grinding time or Blaine fineness of cement {ge}5000 cm{sup 2}/g, the slump loss, air content stability, bleeding, autogenous temperature rise, setting times, and compressive strength of the concrete made with the superplasticized cements were generally comparable to those of the concrete made with the control Portland cements when the superplasticizer was added at the concrete mixer.

  2. Addition of cement to lime-based mortars: Effect on pore structure and vapor transport

    International Nuclear Information System (INIS)

    The main focus of this work is to determine the effect of cement addition, a common practice in many restorations, on the pore structure of lime-based mortars. A second target is to establish correlations between microstructure and water vapor transport across the mortar, which is a key characteristic of building decay. In order to achieve these objectives, we prepared a set of mortars consisting of air-hardening lime with a progressively increasing cement content, as well as a mortar containing hydraulic lime. Several different techniques, most notably mercury intrusion porosimetry and scanning electron microscopy in the backscatter mode, were used to investigate the pore structure. The results from these procedures led to the conclusion that porosity and pore size are progressively reduced as cement content increases. Moreover, an excellent correlation between pore radius parameter and the vapor diffusion coefficient was established. Hydraulic lime mortar exhibited textural parameters and diffusivity values halfway between those of the different lime/cement mixes studied

  3. Inlfuence of Specimen Size on Compression Behavior of Cement Paste and Mortar under High Strain Rates

    Institute of Scientific and Technical Information of China (English)

    CHEN Xudong; CHEN Chen; QIAN Pingping; XU Lingyu

    2016-01-01

    Static and dynamic compression tests were carried out on mortar and paste specimens of three sizes (f68 mm×32 mm,f59 mm×29.5 mm andf32 mm×16 mm) to study the inlfuence of specimen size on the compression behavior of cement-based materials under high strain rates. The static tests were applied using a universal servo-hydraulic system, and the dynamic tests were applied by a spilt Hopkinson pressure bar (SHPB) system. The experimental results show that for mortar and paste specimens, the dynamic compressive strength is greater than the quasi-static one, and the dynamic compressive strength for specimens of large size is lower than those of small size. However, the dynamic increase factors (DIF) has an opposite trend. Obviously, both strain rate and size effect exist in mortar and paste. The test results were then analyzed using Weibull, Carpinteri and Bažant’s size effect laws. A good agreement between these three laws and the test results was reached on the compressive strength. However, for the experimental results of paste and cement mortar, the size effect is not evident for the peak strain and elastic modulus of paste and cement mortar.

  4. Experimental study on thermo-mechanical properties of Polymer Modified Mortar

    International Nuclear Information System (INIS)

    Highlights: • We studied thermal and mechanical properties of ordinary and Polymer Modified Mortars. • For ordinary and polymer samples with different contents of Portland cement were used. • XDM, DSC and SEM were conducted to examine the interaction of the polymer mortars used. • Real improvement of the polymer mortars thermal properties was observed in comparison with ordinary ones. • Decrease of the mechanical strength of polymer mortars was observed when HDPE is added. - Abstract: This paper presents the results of an experimental program devoted to the study of Polymer Modified Mortars’ (PMM) thermal conductivity, thermal diffusivity and calorific capacity at different temperatures and compressive and flexural strengths at room-temperature. For this purpose, Ordinary Mortar (OM) and PMM samples with different contents and through partial substitution of Portland cement were prepared. A real improvement of the PMM thermal properties was observed in comparison with those of OM despite the decrease of mechanical strength. X-rays Diffract Meter (XDM), Differential Scanning Calorimetry (DSC) and Scanning Electron Microscope (SEM) were also conducted to show the interaction of the polymer material considered

  5. Influence of fly ash fineness on water requirement and shrinkage of blended cement mortars

    Directory of Open Access Journals (Sweden)

    Vanissorn Vimonsatit

    2015-12-01

    Full Text Available In this paper, the influence of fly ash fineness on water requirement and shrinkage of blended cement mortar was studied. The results indicate that the water requirement and shrinkage characteristic of the blended cement mortar are dependent on fly ash fineness and replacement level. The use of coarse fly ash slightly reduces the water requirement but greatly reduced the drying and the autogenous shrinkage of the blended cement mortars and the reduction is more with an increase in the fly ash replacement level. The finer fly ashes further reduce the water requirement, but increase the drying and the autogenous shrinkages as compared with coarser fly ash. The incorporation of superplasticizer drastically reduces the water requirement, but the effect on the drying and autogenous shrinkages of the normal Portland cement mortar is small. However, for the fly ash mortar, the use of superplasticizer results in a decrease in drying shrinkage and in a substantial increase in the autogenous shrinkage particularly for the fine fly ash at a high replacement level.

  6. Mechanical Properties and Solidiifed Mechanism of Tailings Mortar with Waste Glass

    Institute of Scientific and Technical Information of China (English)

    NING Baokuan; XU Jingwen; CHEN Sili

    2015-01-01

    In order to improve the comprehensive utilization of solid waste such as iron tailings and waste glass and so on, mechanical property test of cement tailings mortar mixed waste glass and curing mechanism research were conducted in the key materials mechanics lab of Liaoning province. The experimental results show that adding waste glass particles can improve the grain size distribution of tailings. The effect is proportional to the content. The compressive strength of tailings mortar has increased signiifcantly. The ifneness modulus of tailings mortar mixture adding waste glass powder was gradually reducing with the increase of the dosage of waste glass powder, but the compressive strength of the mixture has gradually enhanced with the increase of the dosage. Microscopic analysis shows that the waste glass particles in the mortar mainly play a role of coarse aggregate and glass powder after grinding fine below a certain size shows strong volcanic activity, which can act hydration with tailings, at the same time glass powder also, plays a role in ifne aggregate iflling. Therefore, all of glass particles and glass powder can be used as the additive material for improving and optimizing the mechanical property of tailings mortar.

  7. Lime-pozzolana mortars in Roman catacombs: composition, structures and restoration

    International Nuclear Information System (INIS)

    Analyses of microsamples collected from Roman catacombs and samples of lime-pozzolana mortars hardened in the laboratory display higher contents in carbonated binder than other subaerial Roman monuments. The measured environmental data inside the Saint Callistus and Domitilla catacombs show a constant temperature of 15-17 deg C, a high CO2 content (1700 to 3500 ppm) and a relative humidity close to 100%. These conditions and particularly the high CO2 concentration speed-up the lime calcitization roughly by 500% and reduce the cationic diffusion to form hydrous calcium aluminosilicates. The structure of Roman catacomb mortars shows (i) coarser aggregates and thicker beds on the inside, (ii) thin, smoothed, light and fine-grained external surfaces with low content of aggregates and (iii) paintings and frescoes on the outside. The observed high porosity of the mortars can be attributed to cracking after drying linked with the high binder content. Hardened lime lumps inside the binder denote low water/mortar ratios for slaking. The aggregate tephra pyroclasts rich in aluminosilicate phases with accessorial amounts of Ba, Sr, Rb, Cu and Pb were analysed through X-ray diffraction (XRD), electron microprobe analysis (EMPA) and also by environmental scanning electron microscopy (ESEM) to identify the size and distribution of porosity. Results support procedures using local materials, special mortars and classic techniques for restoration purposes in hypogeal backgrounds

  8. Properties, characterization, and decay of sticky rice–lime mortars from the Wugang Ming dynasty city wall (China)

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Ya [State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083 (China); Cultural Relics and Archaeology Institute of Hunan, Changsha 410083 (China); Fu, Xuan; Gu, Haibing [Cultural Relics and Archaeology Institute of Hunan, Changsha 410083 (China); Gao, Feng [State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083 (China); Liu, Shaojun, E-mail: liumatthew@csu.edu.cn [State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083 (China)

    2014-04-01

    Urgent restoration of the Wugang Ming dynasty city wall brings about the need for a study of the formulation and properties of mortars. In the present paper, mortar samples from the Wugang Ming dynasty city wall were characterized in a combination of sheet polarized light optical microscopy, scanning electron microscopy with X-ray energy dispersive spectrometer, thermogravimetric/differential scanning calorimetry, X-ray powder diffraction, Fourier transform infrared spectroscopy, and inductively coupled plasma emission spectroscopy. Results show that mortars are mainly built up from inorganic calcium carbonate based organic–inorganic hybrid material with a small amount of sticky rice, which plays a crucial role in forming dense and compact microstructure of mortars and effectively hindering penetration of water and air into mortars. Analysis of decayed products shows that the detrimental soluble salts originates from ambient environment. - Highlights: • Mortars used in the Wugang city wall are a calcium carbonate-sticky rice hybrid bonding material. • Carbonation processing is extremely slow due to dense and compact microstructure of mortars. • Decying of mortars results from the appearance of soluble salt from ambient environment.

  9. Properties, characterization, and decay of sticky rice–lime mortars from the Wugang Ming dynasty city wall (China)

    International Nuclear Information System (INIS)

    Urgent restoration of the Wugang Ming dynasty city wall brings about the need for a study of the formulation and properties of mortars. In the present paper, mortar samples from the Wugang Ming dynasty city wall were characterized in a combination of sheet polarized light optical microscopy, scanning electron microscopy with X-ray energy dispersive spectrometer, thermogravimetric/differential scanning calorimetry, X-ray powder diffraction, Fourier transform infrared spectroscopy, and inductively coupled plasma emission spectroscopy. Results show that mortars are mainly built up from inorganic calcium carbonate based organic–inorganic hybrid material with a small amount of sticky rice, which plays a crucial role in forming dense and compact microstructure of mortars and effectively hindering penetration of water and air into mortars. Analysis of decayed products shows that the detrimental soluble salts originates from ambient environment. - Highlights: • Mortars used in the Wugang city wall are a calcium carbonate-sticky rice hybrid bonding material. • Carbonation processing is extremely slow due to dense and compact microstructure of mortars. • Decying of mortars results from the appearance of soluble salt from ambient environment

  10. Performance of Styrene Butadiene Rubber as a Concrete Repair Material in tropical climate

    Science.gov (United States)

    Radhakrishnan, R.; Prakash, V. Syam; Thampan, C. K.; Varma, Prasad

    2012-11-01

    Deterioration of Concrete due to variety of reasons like corrosion of steel, inferior quality of materials as well as workmanship and exposure to aggressive environment like thermal cycling affect the performance or damage a number of Reinforced cement concrete structures. In order to repair these structures for enhancing the service life, number of methods and materials are available. But the degree of success of any repair in concrete depends mainly on the correct choice and the method of application of repair materials. This paper discusses the details of an experimental investigation on the performance of Styrene ñ Butadiene Rubber (SBR) as a concrete repair material in tropical climatic conditions. Resistance to water penetration and tensile cracking are two important performance criteria for any repair material. Cement mortar cubes of mix proportion 1:3 with SBR added at the rate of 20% of the weight of cement, and control specimens without SBR were made. Compressive strength and sorptivity values of the cubes were determined. Shear Bond strength (by slant shear test) and splitting tensile strength of the repaired cylinder specimens of standard dimensions, in which SBR used as a bonding agent were determined. These values were compared with the values obtained for the similar specimens, in which the bonding agent applied was conventional cement slurry. The influence of thermal cycling on the properties of repaired concrete specimens were also studied. A comparison has also been made with the values required to meet the standard specifications of a repair material.

  11. Penetration of corrosion products and corrosion-induced cracking in reinforced cementitious materials

    DEFF Research Database (Denmark)

    Michel, Alexander; Pease, Brad J.; Peterova, Adela;

    2014-01-01

    -induced corrosion (10, 50, and 100 mu A/cm(2)). X-ray attenuation measurements and visual investigations provided both qualitative and quantitative information on the penetration of solid corrosion products into the surrounding cementitious matrix. X-ray attenuation measurements provided time- and location-dependent...... concentrations of corrosion products averaged through the specimen thickness. Digital image correlation (DIC) was used to measure corrosion-induced deformations including deformations between steel and cementitious matrix as well as formation and propagation of corrosion-induced cracks. Based on experimental...... corrosion products. The conceptual model was implemented into a FEM based cracking model and compared to experimental results provided in the literature and obtained from DIC measurements. (C) 2013 Elsevier Ltd. All rights reserved....

  12. Characteristics of Cast Stone cementitious waste form for immobilization of secondary wastes from vitrification process

    Science.gov (United States)

    Chung, Chul-Woo; Um, Wooyong; Valenta, Michelle M.; Sundaram, S. K.; Chun, Jaehun; Parker, Kent E.; Kimura, Marcia L.; Westsik, Joseph H.

    2012-01-01

    The high-temperature in vitrification process of radioactive wastes could cause radioactive technetium ( 99Tc) in secondary liquid wastes to become volatile. Solidified cementitious waste forms at low temperature were developed to immobilize radioactive secondary waste. This research focuses on the characterization of a cementitious waste form called Cast Stone. Properties including compressive strength, surface area, phase composition, and technetium leaching were measured. The results indicate that technetium diffusivity is affected by simulant type. Additionally, ettringite and AFm (Al 2O 3-Fe 2O 3-mono) main crystalline phases were formed during hydration. The Cast Stone waste form passed the qualification requirements for a secondary waste form, which are compressive strength of 3.45 MPa and technetium diffusivity of 10 -9 cm 2/s. Cast Stone was found to be a good candidate for immobilizing secondary waste streams.

  13. Effect of hybrid fiber reinforcement on the cracking process in fiber reinforced cementitious composites

    DEFF Research Database (Denmark)

    Pereira, Eduardo B.; Fischer, Gregor; Barros, Joaquim A.O.

    2012-01-01

    tensile deformations in the composite, the fibers with different geometrical and mechanical properties restrain the propagation and further development of cracking at different scales from the micro- to the macro-scale. The optimized design of the fiber reinforcing systems requires the objective......The simultaneous use of different types of fibers as reinforcement in cementitious matrix composites is typically motivated by the underlying principle of a multi-scale nature of the cracking processes in fiber reinforced cementitious composites. It has been hypothesized that while undergoing...... materials is carried out by assessing directly their tensile stress-crack opening behavior. The efficiency of hybrid fiber reinforcements and the multi-scale nature of cracking processes are discussed based on the experimental results obtained, as well as the micro-mechanisms underlying the contribution of...

  14. About microcracking due to leaching in cementitious composites: X-ray microtomography description and numerical approach

    International Nuclear Information System (INIS)

    Chemical shock of cement based materials leads to significant degradation of their physical properties. A typical scenario is a calcium leaching due to water (water with very low pH compared with that of pore fluid). The main objective of this paper is to evaluate the evolution of microstructure induced by leaching of a cementitious composite using synchrotron X-ray micro tomography, mainly from an experimental point of view. In this particular case, it was possible to identify cracking induced by leaching. After a description of the degradation mechanism and the X-ray synchrotron microtomographic analysis, numerical simulations are performed in order to show that cracking is induced by an initial pre-stressing of the composite, coupled with decalcification shrinkage and dramatic decrease in tensile strength during leaching. X-ray microtomography analysis allowed to make evidence of an induced microcracking in cementitious material submitted to leaching.

  15. Effect of phase separation structure on cementitious reactivity of blast furnace slag

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Blast furnace slag samples with phase separation structure were prepared by re-melting and then water quenching process. By use of XRD,DTA and SEM technologies in combination with mechanical property experiment,the structure characteristics of samples were determined and their effects on cementitious reactivity were investigated. The results show that the samples with phase separation have better cementitious reactivity than sample with homogenous glass and sample with crystalline phases,which mainly contributes to its glass structure with coexistence of Ca-O rich phase and Si-O rich phase. Moreover,the amorphous samples possess hydrability which is affected by their formation process,since phase separation extends the range of possible Ca-rich crystalline phases.

  16. Setting and Strength Characteristics of Alkali-activated Carbonatite Cementitious Materials with Ground Slag Replacement

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The effect of the ground granulated blast-furnace slag (GGBFS) addition, the modulus n (mole ratio of SiO2 to Na2 O ) and the concentration of sodium silicate solution on the compressive strength of the ma terial, i e alkali-activated carbonatite cementitious material (AACCMfor short ) was investigated.In addition, it is found that barium chloride has a satisfactory retarding effect on the setting of AACCM in which more than 20% ( by mass ) groud carbonatite was replaced by GGBFS.As a result, a cementitious material, inwhich ground carbona tite rock served as dominative starting material, with 3-day and 28-da y compressive strength greater than 30 MPa and 60 MPa and with continuous strength gain beyond 90 days was obtained.

  17. Ion Transport and Microstructure of Sandwich Cementitious Materials Exposed to Chloride Environment

    Institute of Scientific and Technical Information of China (English)

    WANG Xingang; WANG Kai; WANG Rui; XIE Tao; HUANG Jie

    2015-01-01

    Ion transport of sandwich cementitious materials (SCM) exposed to chloride environment was investigated by accelerated diffusion method and natural diffusion method. Pore structure and micromorphology of SCM were investigated by MIP and SEM-EDS. In comparison with the monolayer structural high performance concrete (HPC), conductive charge for 6 hours, chloride diffusion coefficient, and apparent chloride diffusion coefifcient of SCM were decreased by 30%-40%, two orders of magnitude and 40%-50%, respectively. Pore structure of ultra low ion permeability cementitious materials (ULIPCM) prepared for the facesheet is superior to that of HPC prepared for the core. As for porosity, the most probable pore radius, the content of pores with radius 50 nm and the surface area of pores, the order is ULIPCM

  18. Transition from Multiple Macro-Cracking to Multiple Micro-Cracking in Cementitious Composites

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jun; LENG Bing

    2008-01-01

    This paper presents an experimental study of the possibility of transition from multiple macro-cracking to multiple micro-cracking in cementitious composites.Conventional polyvinyl alcohol fiber reinforced cementitious composites normally exhibit macroscopic strain-hardening and multiple cracking after the first cracks appear.However,the individual crack width at the saturated stage is normally 60 to 80 μm.In the current study,the effect of fine aggregate size on the cracking performance,especially the individual crack width in the strain-hardening stage was studied by bending tests.The results show that the individual crack widths can be reduced from 60-80 μm to 10-30 μm by modifying the particle size of the fine aggregates used in the composites.

  19. Effect of phase separation structure on cementitious reactivity of blast furnace slag

    Institute of Scientific and Technical Information of China (English)

    LI Yu; SUN HengHu; LIU XiaoMing; CUI ZengDi

    2009-01-01

    Blast furnace slag samples with phase separation structure were prepared by re-melting and then water quenching process. By use of XRD, DTA and SEM technologies in combination with mechanical prop-erty experiment, the structure characteristics of samples were determined and their effects on cemen-titious reactivity were investigated. The results show that the samples with phase separation have better cementitious reactivity than sample with homogenous glass and sample with crystalline phases, which mainly contributes to its grass structure with coexistence of Ca-O rich phase and Si-O rich phase. Moreover, the amorphous samples possess hydrability which is affected by their formation process, since phase separation extends the range of possible Ca-rich crystalline phases.

  20. Leaching experiment of alkali-activated cementitious materials solidified forms of radioactive incineration ash

    International Nuclear Information System (INIS)

    In order to solidify safely radioactive incineration ash, the alkali-activated cementitious materials were prepared with slag, fly ash, cement and zeolite, with water glass or sodium silicate (sulfate) as the activator. The recommended formulation of solidification matrix is 65% (mass fraction, the same below) slag, 10% fly ash, 20% zeolite, 2% cement, 3% Ca (OH)2. Adding quantity of water glass is 5%, when addition of 30% radioactive incineration ash, with 0.34-0.35 of the ratio of water and ash, the mechanical property of solidification forms performs well. The leaching rate of U for the cement wastes forms is 6.0 x 10-6 cm/d in 35 d, and the long time leaching rate is very low. The results of diffusion coefficient of U in the solidification forms indicate that retention capability about U of alkali-activated cementitious materials si good. The leaching mechanisms of solidification forms are discussed. (authors)

  1. Keratin film ablation for the fabrication of brick and mortar skin structure using femtosecond laser pulses

    Science.gov (United States)

    Haq, Bibi Safia; Khan, Hidayat Ullah; Dou, Yuehua; Alam, Khan; Attaullah, Shehnaz; Zari, Islam

    2015-09-01

    The patterning of thin keratin films has been explored to manufacture model skin surfaces based on the "bricks and mortar" view of the relationship between keratin and lipids. It has been demonstrated that laser light is capable of preparing keratin-based "bricks and mortar" wall structure as in epidermis, the outermost layer of the human skin. "Bricks and mortar" pattern in keratin films has been fabricated using an ArF excimer laser (193 nm wavelength) and femtosecond laser (800 and 400 nm wavelength). Due to the very low ablation threshold of keratin, femtosecond laser systems are practical for laser processing of proteins. These model skin structures are fabricated for the first time that will help to produce potentially effective moisturizing products for the protection of skin from dryness, diseases and wrinkles.

  2. The Effects of Different Fine Recycled Concrete Aggregates on the Properties of Mortar

    Directory of Open Access Journals (Sweden)

    Cheng-Chih Fan

    2015-05-01

    Full Text Available The practical use of recycled concrete aggregate produced by crushing concrete waste reduces the consumption of natural aggregate and the amount of concrete waste that ends up in landfills. This study investigated two methods used in the production of fine recycled concrete aggregate: (1 a method that produces fine as well as coarse aggregate, and (2 a method that produces only fine aggregate. Mortar specimens were tested using a variety of mix proportions to determine how the characteristics of fine recycled concrete aggregate affect the physical and mechanical properties of the resulting mortars. Our results demonstrate the superiority of mortar produced using aggregate produced using the second of the two methods. Nonetheless, far more energy is required to render concrete into fine aggregate than is required to produce coarse as well as fine aggregate simultaneously. Thus, the performance benefits of using only fine recycled concrete aggregate must be balanced against the increased impact on the environment.

  3. Preparation and Characterization of New Geopolymer-Epoxy Resin Hybrid Mortars

    Directory of Open Access Journals (Sweden)

    Raffaele Cioffi

    2013-07-01

    Full Text Available The preparation and characterization of metakaolin-based geopolymer mortars containing an organic epoxy resin are presented here for the first time. The specimens have been prepared by means of an innovative in situ co-reticulation process, in mild conditions, of commercial epoxy based organic resins and geopolymeric slurry. In this way, geopolymer based hybrid mortars characterized by a different content of normalized sand (up to 66% in weight and by a homogeneous dispersion of the organic resin have been obtained. Once hardened, these new materials show improved compressive strength and toughness in respect to both the neat geopolymer and the hybrid pastes since the organic polymer provides a more cohesive microstructure, with a reduced amount of microcracks. The microstructural characterization allows to point out the presence of an Interfacial Transition Zone similar to that observed in cement based mortars and concretes. A correlation between microstructural features and mechanical properties has been studied too.

  4. Effect of Functional Chemical Admixtures on the Performance of Cement Asphalt Mortar Used in Ballastless Track

    Institute of Scientific and Technical Information of China (English)

    JIANG Jinyang; SHE Wei; LI Wei; PAN Li

    2015-01-01

    Chemical admixtures are of paramount importance to the performance of modern cement based composites. In this paper, we performed a series of tests to investigate the effects of chemical admixtures on the cement asphalt mortar (CA mortar), i e, compressive strength, frost resistance, permeability, fatigue resistance, pore structure and microstructure. In particular, two types of chemical admixtures were tested,i e, defoamer (tributyl phosphate (TBP)) and polycarboxylate superplasticizer (PS). The results indicate that the addition of TBP and PS eliminates big bubbles and promotes small non-connected pores forming in matrix. Besides, an optimum dosage of TBP and PS may be determined with respect to the frost resistance, permeability and fatigue resistance of CA mortar. Further elaborative discussions are presented as well as experimental evidences from mercury intrusion porosimetry, scanning electron microscopy and energy dispersive spectroscopy.

  5. Experimental Investigation of Lime Mortar Used in Historical Buildings in Becin, Turkey

    Directory of Open Access Journals (Sweden)

    Adem SOLAK

    2016-03-01

    Full Text Available It is of great importance that the architectural and engineering disciplines work together in the restoration studies of historical buildings which are our cultural heritages. It is required that the bearing system and the materials of the structures should be investigated in detail prior to any conservation. The determination of the properties and compositions of the mortar material used in the construction of the historical building is one of the most important phases of the conservation studies and it is the main purpose of this study. In the scope of the study, the basic physical and mechanical properties, micro structures, raw material compositions, mineralogical and chemical properties of historical mortars taken from Kizil Khan, Karapasah Madrasah and Yelli Mosque structures in Becin antique city are determined. As a result of the study, it is determined that all mortar samples have hydraulic properties that is a result of hydraulic properties of binder lime.

  6. Application of a semi-empirical model for the evaluation of transmission properties of barite mortar

    International Nuclear Information System (INIS)

    The aim of this study was to estimate barite mortar attenuation curves using X-ray spectra weighted by a workload distribution. A semi-empirical model was used for the evaluation of transmission properties of this material. Since ambient dose equivalent, H⁎(10), is the radiation quantity adopted by IAEA for dose assessment, the variation of the H⁎(10) as a function of barite mortar thickness was calculated using primary experimental spectra. A CdTe detector was used for the measurement of these spectra. The resulting spectra were adopted for estimating the optimized thickness of protective barrier needed for shielding an area in an X-ray imaging facility. - Highlights: • Barite mortar attenuation curves using X-ray spectra were calculated. • Optimized thickness of protective barrier was estimated. • An optimized model considers the energy spectra for protective barrier calculation

  7. Dry ripened mortar with quarry waste and rubber powder from unserviceable tires

    Directory of Open Access Journals (Sweden)

    José Aparecido Canova

    2015-01-01

    Full Text Available Stone-quarry fines have been evaluated in mortar and concrete, but have presented drying shrinkage and consequently higher incidence of cracks than those with natural sand. This study compared the dry ripened mortar in two types of aggregates added of 8% rubber powder. It was used quicklime, artificial and natural sand in volumetric proportions of 1:6. Mixtures were oven-dried, received the cement, establishing the volumetric proportion of 1: 1.5:9. Inplastic state, we evaluated aspects such as consistence, air content, water retention and bleeding; whereas compressive strength, static deformation modulus and water absorption by capillarity was determined in hardened state. Cracking aspects were evaluated in substrate. As a result, the mortar with artificial sand showed higher increases in compressive strength, capillarity rate and cracking, and greater reductions in air content and bleeding. As for the rubber powder, exhibited a greater reduction in the cracking rate and capillarity was found.

  8. EXPERIMENTAL STUDY ON THE APPLICATION OF HIGH STRENGTH FIBER REINFORCED MORTAR TO PRESTRESSED CONCRETE STRUCTURES

    Science.gov (United States)

    Sakurada, Michihiro; Mori, Takuya; Ohyama, Hiroaki; Seki, Hiroshi

    In order to study the application of high strength fiber reinforced mortar which has design compressive strength 120N/mm2 to prestressed concrete structures, the authors carried out material tests, bending tests and shear tests of prestressed concrete beam specimens. From the material tests, we obtained material properties for the design of prestressed concrete structures such as compressive strength, tensile strength, Young's modulus, coefficient of creep, dry shrinkage and so on. The results of the bending tests and the shear tests of prestressed concrete beam specimen shows that experimental flexural strength and shear strength of prestressed concrete beam using high strength fiber reinforced mortar exceeds strength calculated by traditional design method. It is confirmed that high strength fiber reinforced mortar can be applied to prestressed concrete structures.

  9. Performance Characteristics of Waste Glass Powder Substituting Portland Cement in Mortar Mixtures

    Science.gov (United States)

    Kara, P.; Csetényi, L. J.; Borosnyói, A.

    2016-04-01

    In the present work, soda-lime glass cullet (flint, amber, green) and special glass cullet (soda-alkaline earth-silicate glass coming from low pressure mercury-discharge lamp cullet and incandescent light bulb borosilicate glass waste cullet) were ground into fine powders in a laboratory planetary ball mill for 30 minutes. CEM I 42.5N Portland cement was applied in mortar mixtures, substituted with waste glass powder at levels of 20% and 30%. Characterisation and testing of waste glass powders included fineness by laser diffraction particle size analysis, specific surface area by nitrogen adsorption technique, particle density by pycnometry and chemical analysis by X-ray fluorescence spectrophotometry. Compressive strength, early age shrinkage cracking and drying shrinkage tests, heat of hydration of mortars, temperature of hydration, X-ray diffraction analysis and volume stability tests were performed to observe the influence of waste glass powder substitution for Portland cement on physical and engineering properties of mortar mixtures.

  10. Influence of Curing Condition on the Adhesive Strength of EVA Modified Mortar to Tile

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The reducing water effectiveness of EVA latex and powder was observed. Adhesive strength of EVA modified mortar to tile under different curing condition was studied. And the adhesive strengths of mortars modified by EVA latex and by EVA powder were compared. The results show that the reducing water effectiveness is improved by 36.12% and 21.55%, respectively, when the content of EVA latex and powder are 8% and 4%. EVA latex and powder can improve the adhesive strength of modified mortar to tile under the standard curing, high temperature curing, and freeze-thaw circle curing.EVA latex can improve the water resistance obviously, besides improve the adhesive strengths of standard curing and high temperature curing, comparing with EVA powder.

  11. Dating historical calcite mortar by blue OSL: results from known age samples

    International Nuclear Information System (INIS)

    The study investigates whether blue OSL, known as a dating tool for partially bleached materials, can also be used for dating calcite mortar from young constructions. Starting from samples of known age the aim of the study is to determine appropriate evaluation methods for dose distributions. Using a model-calculation we first try to answer the question of how far a mortar sample can possibly be bleached during the manufacturing process. We then deal with the question of optimizing the analytical process, especially in view of the most suitable grain size. In the focus of our investigations we have tested several methods of evaluating frequency distributions based on single aliquot/multiple grain measurements. Depending on grain size, two methods have proved sufficiently successful; optimal equivalent doses may be obtained either from radial plots or from maxima of weighted histograms. The comparison is based on measurements of 14 mortar samples from the last millennium

  12. Physical-mechanical characterization of hydraulic and non-hydraulic lime based mortars for a French porous limestone

    CERN Document Server

    Al-Mukhtar, M

    2006-01-01

    The focus of the study presented in this paper is to provide reliable criteria that can be used to estimate the degree of compatibility between the French limestone tuffeau and mortar. It is suggested through this study to use the same parent material (i.e., tuffeau) as mortar. The mortar used in this study is composed of non-hydraulic (hydrated) lime or hydraulic lime and aggregates obtained from fragments and powder of the tuffeau stone. Water transfer properties and mechanical behaviour of the mortars are evaluated and compared with the original stone Tuffeau. Based on these studies, some key guidelines are provided such that a mortar that is compatible with properties of Tuffeau and can be prepared and used as construction material of monuments and maintenance purposes.

  13. Influence Of The Powder/Asphalt Ratio On The High Stress Responses Of Crumb Rubber Modified Asphalt Mortars

    Directory of Open Access Journals (Sweden)

    Ma Tengfei

    2016-04-01

    Full Text Available In order to study different powder/asphalt ratios effect on nonlinear viscoelastic responses of mortar, this paper choose limestone as the filler, and powder/asphalt ratio is 0.2,0.4,0.6,and 0.8.The tests were conducted using a Dynamic Shear Rheometer to perform multiple stress creep recovery (MSCR tests.The test results show that,with the increase of powder/asphalt ratio irrecoverable creep compliance(Jnr value of the mortar , decrease gradually, and the amplitude is larger.High temperature performance of the mortar are improve obviously.Using environmental scanning electron microscopy to scan those mortars,it analyzed the improvement of mortar from the microcosmic mechanism.

  14. Evaluation of natural colonisation of cementitious materials: effect of bioreceptivity and environmental conditions.

    Science.gov (United States)

    Manso, Sandra; Calvo-Torras, María Ángeles; De Belie, Nele; Segura, Ignacio; Aguado, Antonio

    2015-04-15

    Incorporation of living organisms, such as photosynthetic organisms, on the structure envelope has become a priority in the area of architecture and construction due to aesthetical, economic and ecological advantages. Important research efforts are made to achieve further improvements, such as for the development of cementitious materials with an enhanced bioreceptivity to stimulate biological growth. Previously, the study of the bioreceptivity of cementitious materials has been carried out mainly under laboratory conditions although field-scale experiments may present different results. This work aims at analysing the colonisation of cementitious materials with different levels of bioreceptivity by placing them in three different environmental conditions. Specimens did not present visual colonisation, which indicates that environmental conditions have a greater impact than intrinsic properties of the material at this stage. Therefore, it appears that in addition to an optimized bioreceptivity of the concrete (i.e., composition, porosity and roughness), extra measures are indispensable for a rapid development of biological growth on concrete surfaces. An analysis of the colonisation in terms of genus and quantity of the most representative microorganisms found on the specimens for each location was carried out and related to weather conditions, such as monthly average temperature and total precipitation, and air quality in terms of NOx, SO2, CO and O3. OPC-based specimens presented a higher colonisation regarding both biodiversity and quantity. However, results obtained in a previous experimental programme under laboratory conditions suggested a higher suitability of Magnesium Phosphate Cement-based (MPC-based) specimens for algal growth. Consequently, carefully considering the environment and the relationships between the different organisms present in an environment is vital for successfully using a cementitious material as a substrate for biological growth. PMID

  15. Direct assessment of tensile stress-crack opening behavior of Strain Hardening Cementitious Composites (SHCC)

    OpenAIRE

    Pereira, E. N. B.; Fischer, G.; Barros, Joaquim A. O.

    2012-01-01

    The process of designing Strain Hardening Cementitious Composites (SHCC) is driven by the need to achieve certain performance parameters in tension. These are typically the pseudo-strain hardening behavior and the ability to develop multiple cracks. The assessment of the tensile load-deformation of these materials is therefore of great importance and is frequently carried out by characterizing the material tensile stress-strain behavior. In this paper an alternative approach...

  16. Characterization of cracking in strain hardening cementitious composites using the compact tension test

    OpenAIRE

    Pereira, E. N. B.; Fischer, G.; Barros, Joaquim A. O.

    2012-01-01

    The characterization of the tensile behavior of strain hardening cementitious composites (SHCC) is of significant importance to the material design. In a previous work the tensile stress-crack opening response of different types of SHCC was characterized using notched specimens tested in direct tension, where a single crack was obtained and mechanically characterized by performing Single Crack Tension Test (SCTT). In this study the tensile behavior of SHCC materials is charact...

  17. Design of microcapsule system used for self-healing cementitious material

    OpenAIRE

    Zhang, M.; Han, N.; Xing, F.; Schlangen, H.E.J.G.

    2013-01-01

    For a microcapsule based self-healing system in the cementitious material, a fundamental issue is to find and facilitate a suitable microcapsule system, concerning either the material selection or design and manufacture process. In this study, urea formaldehyde resin is used for the shell of microcapsule, and bisphenol – an epoxy resin E-51 diluted by n-butyl glycidy ether (BGE) is adopted as the heal-agent inside the microcapsule. The production process mainly includes pre-polymerization pre...

  18. Durability based life cycle assessment of concrete with supplementary cementitious materials exposed to carbonation

    OpenAIRE

    Van den Heede, Philip; De Belie, Nele

    2015-01-01

    Until now, it remains unclear how "green" concrete compositions with high volumes of supplementary cementitious materials really are, especially when subject to carbonation-induced steel corrosion. This paper results from accelerated carbonation tests for high-volume fly ash (HVFA) and fly ash + silica fume (FA+SF) concrete. They served as input for a probabilistic service life prediction on fib Bulletin 34, and a subsequent life cycle assessment. the inverse effective carbonation resistance ...

  19. Various durability aspects of cement pastes and concretes with supplementary cementitious materials

    OpenAIRE

    SAILLIO, Mickael; BAROGHEL BOUNY, Véronique; PRADELLE, Sylvain

    2016-01-01

    The use of supplementary cementitious materials (SCMs) as a constituent for concrete receives considerable attention, due to the lower CO2 emission of these materials compared to the production of classic Portland cement. Furthermore, concretes incorporating SCMs show some improved durability properties. SCMs are mainly pozzolanic materials (Fly Ash or Metakaolin) or alkali-activated materials such as ground granulated blast slag (GGBS). In this paper, the durability of concretes and cement p...

  20. Self-healing of Micro-cracks in Engineered Cementitious Composites

    OpenAIRE

    Suryanto B.; Wilson S.A.; McCarter W.J.

    2015-01-01

    The performance of an Engineered Cementitious Composite (ECC) to self-heal micro-cracks under a controlled laboratory environment is presented. Ten dog-bone shaped samples were prepared; five of them were preloaded to known strains and then left to heal in water in a temperature-controlled laboratory. Ultrasonic pulse velocity (UPV) measurements were undertaken to monitor the crack-healing process. It was found that all samples exhibited recoveries in UPV and were able to recover to betwee...