Stabilization/solidification of selenium-impacted soils using Portland cement and cement kiln dust.

Science.gov (United States)

Moon, Deok Hyun; Grubb, Dennis G; Reilly, Trevor L

2009-09-15

Stabilization/solidification (S/S) processes were utilized to immobilize selenium (Se) as selenite (SeO(3)(2-)) and selenate (SeO(4)(2-)). Artificially contaminated soils were prepared by individually spiking kaolinite, montmorillonite and dredged material (DM; an organic silt) with 1000 mg/kg of each selenium compound. After mellowing for 7 days, the Se-impacted soils were each stabilized with 5, 10 and 15% Type I/II Portland cement (P) and cement kiln dust (C) and then were cured for 7 and 28 days. The toxicity characteristic leaching procedure (TCLP) was used to evaluate the effectiveness of the S/S treatments. At 28 days curing, P doses of 10 and 15% produced five out of six TCLP-Se(IV) concentrations below 10mg/L, whereas only the 15% C in DM had a TCLP-Se(IV) concentration soil-cement slurries aged for 30 days enabled the identification of Se precipitates by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX). XRD and SEM-EDX analyses of the Se(IV)- and Se(VI)-soil-cement slurries revealed that the key selenium bearing phases for all three soil-cement slurries were calcium selenite hydrate (CaSeO(3).H(2)O) and selenate substituted ettringite (Ca(6)Al(2)(SeO(4))(3)(OH)(12).26H(2)O), respectively.

compaction delay versus properties of cement-bound lateritic soil

African Journals Online (AJOL)

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hour intervals on soil-cement mixes 3,5,8; and 1, 3, 5 percent cement contents by weight of dry soils, for ... stabilized soils were the Compaction test (Standard Proctor), the Unconfined Compressive. Strength .... Plastic limit (%). % passing BS ...

Triaxial shear behavior of a cement-treated sand–gravel mixture

Directory of Open Access Journals (Sweden)

Younes Amini

2014-10-01

Full Text Available A number of parameters, e.g. cement content, cement type, relative density, and grain size distribution, can influence the mechanical behaviors of cemented soils. In the present study, a series of conventional triaxial compression tests were conducted on a cemented poorly graded sand–gravel mixture containing 30% gravel and 70% sand in both consolidated drained and undrained conditions. Portland cement used as the cementing agent was added to the soil at 0%, 1%, 2%, and 3% (dry weight of sand–gravel mixture. Samples were prepared at 70% relative density and tested at confining pressures of 50 kPa, 100 kPa, and 150 kPa. Comparison of the results with other studies on well graded gravely sands indicated more dilation or negative pore pressure in poorly graded samples. Undrained failure envelopes determined using zero Skempton's pore pressure coefficient (A¯=0 criterion were consistent with the drained ones. Energy absorption potential was higher in drained condition than undrained condition, suggesting that more energy was required to induce deformation in cemented soil under drained state. Energy absorption increased with increase in cement content under both drained and undrained conditions.

3.4. Durability of soil-cement mixtures influenced by hostile environment

International Nuclear Information System (INIS)

Saidov, D.Kh.

2011-01-01

It is determined that soil-cement mixture is one of most perspective materials, that can substitute concrete. Experiments on revelation of magnesium sulphate influence on soil-cement mixtures were carried out. Data on granulometric composition and physical parameters of loess soils is presented in this article. Portland cement M 400 was used as binder. According to the results it is concluded that stability of soil-cement mixtures from loess soils in solutions of magnesium sulphate depends on concentration of solution.

Immobilization of lead in shooting range soils by means of cement, quicklime, and phosphate amendments.

Science.gov (United States)

Cao, Xinde; Dermatas, Dimitris; Xu, Xuanfeng; Shen, Gang

2008-03-01

Lead (Pb) contamination at shooting range sites is increasingly under environmental concern. Controlling Pb leachability from shooting range soil media is an important step to minimize Pb exposure to the surrounding environment. This study investigated stabilization of Pb in shooting range soils treated with cement, quicklime, and phosphate. Two soils were used and collected from two shooting ranges, referred to as SR1 and SR2. The treatment additives were applied to the soils at rates from 2.5% to 10% (w/w). The effectiveness of each treatment was evaluated by Pb (w/w). The effectiveness of each treatment was evaluated by Pb leachability, measured by the Toxicity Characteristic Leaching Procedure (TCLP). The possible mechanisms for Pb immobilization were elucidated using X-ray powder diffraction (XRPD). Cement and quicklime treatments were effective in immobilizing Pb in SR1 soil, with reduction of Pb concentration in TCLP leachate (TCLP-Pb) to be below the U.S. EPA non-hazardous regulatory limit of 5 mg L(-1) at application rates of > or =5% and 28-d incubation. By contrast, cement and quicklime amendments were less effective for Pb stabilization in SR2 soil because the TCLP-Pb levels in the treated soil were still higher than the limit of 5 mg L(-1) at all application rates, although they were significantly reduced in comparison with the untreated soil. Phosphate application was most effective in reducing Pb leach ing in both soils. Even at an application rate as low as 5% and 1-d incubation, phosphate could reduce TCLP-Pb to be below the limit of 5 mg L(-1) in both soils. Immobilization of Pb in the SR1 soil amended with cement and quicklime was attributed to the formation of pozzolanic minerals (e.g., calcium silicate hydrate C-S-H and ettringite) that could encapsulate soil Pb. The pozzolanic reaction was limited in the SR2 soil upon the application of cement and quicklime. Reduction of the TCLP-Pb might result from complexation of Pb on the surface of the

Geotechnical Properties of Clayey Soil Stabilized with Cement ...

African Journals Online (AJOL)

ADOWIE PERE

2017-12-31

Dec 31, 2017 ... ... to investigate the different effects of cement-sawdust ash and cement on a ... Keywords: Cement, Saw dust, strength test subgrade material, highway construction ... characteristics of lateritic soil stabilized with sawdust ash.

Influence of Rice Husk Ash and Clay in Stabilization of Silty Soils Using Cement

Directory of Open Access Journals (Sweden)

Widjajakusuma Jack

2017-01-01

Full Text Available Soil stabilization is needed to enhance the strength of the soil. One popular method of soil stabilization is using cement. Due to the environmental issue, it is a need to reduce the application of cement and/or to replace partially the cement with other environmental-friendly compounds. One of these compounds is rice husk ash (RSA, which is agricultural wastes. The objective of this paper is to study the influence of RSA and clay as partial replacement to cement in soil stabilization of silt soil with high plasticity (MH using cement. The cement used was ordinary Portland cement, while the RHA was obtained by burning rice husk at temperature of 250°C. The MH soil is stabilized with 4% cement, 4% cement and 3% rice husk ash and 4% cement, 3 % RHA and 3 % clay. The various tests were conducted on the pure and stabilized soils. Results have indicated that application of 4% cement, 3 % RHA and 3 % clay as silt soil stabilization is more favorable in increasing soil strength and reducing brittle behaviour of soil.

Study of incorporation of casting wastes in soil-cement blocks

International Nuclear Information System (INIS)

Folmann, R.; Malkowski, W.; Valentina, L.V.D.; Folgureras, M.V.

2011-01-01

Soil-cement bricks are an ecological alternative to conventional ones because they don't need to be burned to gain strength. This study examines the technical possibility of reuse of foundry sand as fine aggregate in soil-cement. The raw materials were characterized by X-ray diffraction, thermal analysis and particle size. The foundry sand wastes were mixed at different levels to soil and cement. Compaction tests were performed to define the mixtures at optimum moisture content corresponding to the maximum density. Isothermal Conduction Calorimeter was performed to study the influence of waste in the cement hydration reaction. The results indicate that the addition of foundry sand waste decreases the optimum moisture content and increases the maximum density without significantly affecting the cement set. (author)

3.4. Chemical additives and granulometric composition influence on soils armed by cement

International Nuclear Information System (INIS)

Saidov, D.Kh.

2011-01-01

Purpose of this work was to evaluate an influence of various chemical additives on soils armed by portland cement. Experimental research of kinetics of soil cements structure formation after adding the chemicals was carried out. According to the investigations it was determined that structure formation process of soil cements depended on granulometric composition of armed soil, cement quantity, type and quantity of chemical additives.

A Model of Thermal Conductivity for Planetary Soils. 2; Theory for Cemented Soils

Science.gov (United States)

Piqueux, S.; Christensen, P. R.

2009-01-01

A numerical model of heat conduction through particulate media made of spherical grains cemented by various bonding agents is presented. The pore-filling gas conductivity, volume fraction, and thermal conductivity of the cementing phase are tunable parameters. Cement fractions conductivity. A significant conductivity increase (factor 3-8) is observed for bond fractions of 0.01 to 1% in volume. In the 1 to 15% bond fraction domain, the conductivity increases continuously but less intensely (25-100% conductivity increase compared to a 1% bond system). Beyond 15% of cements, the conductivity increases vigorously and the bulk conductivity rapidly approaches that of bedrock. The composition of the cements (i.e. conductivity) has little influence on the bulk thermal inertia of the soil, especially if the volume of bond <10%. These results indicate that temperature measurements are sufficient to detect cemented soils and quantify the amount of cementing phase, but the mineralogical nature of the bonds and the typical grain size are unlikely to be determined from orbit. On Mars, a widespread surface unit characterized by a medium albedo (0.19-0.26) and medium/high thermal inertia (200-600 J s(0.5)/sq m/K) has long been hypothesized to be associated with a duricrust. The fraction of cement required to fit the thermal data is less than approx.1-5% by volume. This small amount of material is consistent with orbital observations, confirming that soil cementation is an important factor controlling the thermal inertia of the Martian surface

The differences between soil grouting with cement slurry and cement-water glass slurry

Science.gov (United States)

Zhu, Mingting; Sui, Haitong; Yang, Honglu

2018-01-01

Cement slurry and cement-water glass slurry are the most widely applied for soil grouting reinforcement project. The viscosity change of cement slurry is negligible during grouting period and presumed to be time-independent while the viscosity of cement-water glass slurry increases with time quickly and is presumed to be time-dependent. Due to the significantly rheology differences between them, the grouting quality and the increasing characteristics of grouting parameters may be different, such as grouting pressure, grouting surrounding rock pressure, i.e., the change of surrounding rock pressure deduced by grouting pressure. Those are main factors for grouting design. In this paper, a large-scale 3D grouting simulation device was developed to simulate the surrounding curtain grouting for a tunnel. Two series of surrounding curtain grouting experiments under different geo-stress of 100 kPa, 150 kPa and 200 kPa were performed. The overload test on tunnel was performed to evaluate grouting effect of all surrounding curtain grouting experiments. In the present results, before 240 seconds, the grouting pressure increases slowly for both slurries; after 240 seconds the increase rate of grouting pressure for cement-water glass slurry increases quickly while that for cement slurry remains roughly constant. The increasing trend of grouting pressure for cement-water glass is similar to its viscosity. The setting time of cement-water glass slurry obtained from laboratory test is less than that in practical grouting where grout slurry solidifies in soil. The grouting effect of cement-water glass slurry is better than that of cement slurry and the grouting quality decreases with initial pressure.

Development of soil-cement blocks with three interventions: natural soil, soil corrected with sand and soil more phase change materials (PCMs)

International Nuclear Information System (INIS)

Dantas, Valter Bezerra; Gomes, Uilame Umbelino; Reis, Edmilson Pedreira; Valcacer, Samara Melo; Silva, A.S.

2014-01-01

In this work, the results of characterization tests of soil samples collected in Mossoro-RN, UFERSA-RN Campus, located approximately 20 meters high, and "5 ° 12'34.68 south latitude and 37 ° 19'5.74 "west longitude, with the purpose of producing soil-cement for the manufacture of pressed blocks with good resistance to compression and thermal stability. The following tests were performed: granulometry, plasticity limit, liquidity limit, particle size correction, scanning electron microscopy (SEM), X-ray fluorescence. In this soil, based on the results of the granulometric analysis, 10% of medium sand with 3% and 5% of eicosane paraffin and 10% of medium sand with 3% and 5% of paraffin 120 / 125F were added, forming analysis compositions, standard soil-cement block and natural soil-cement block with addition of 10% medium sand and 0% paraffin. Paraffins are referred to as PCMs (Phase Change Material). The contrasting effect between the different dosages on the compressive strength values of the soil-cement blocks was observed. The objective is to create new materials that give the block quality equal to or higher than the recommendations of ABNT norms, and that offer greater thermal comfort in the constructions. Soil particles of different sizes were added to 8% (by weight) of cement, and about 9.20% of water added to the mixture

Peach leaf responses to soil and cement dust pollution.

Science.gov (United States)

Maletsika, Persefoni A; Nanos, George D; Stavroulakis, George G

2015-10-01

Dust pollution can negatively affect plant productivity in hot, dry and with high irradiance areas during summer. Soil or cement dust were applied on peach trees growing in a Mediterranean area with the above climatic characteristics. Soil and cement dust accumulation onto the leaves decreased the photosynthetically active radiation (PAR) available to the leaves without causing any shade effect. Soil and mainly cement dust deposition onto the leaves decreased stomatal conductance, photosynthetic and transpiration rates, and water use efficiency due possibly to stomatal blockage and other leaf cellular effects. In early autumn, rain events removed soil dust and leaf functions partly recovered, while cement dust created a crust partially remaining onto the leaves and causing more permanent stress. Leaf characteristics were differentially affected by the two dusts studied due to their different hydraulic properties. Leaf total chlorophyll decreased and total phenol content increased with dust accumulation late in the summer compared to control leaves due to intense oxidative stress. The two dusts did not cause serious metal imbalances to the leaves, except of lower leaf K content.

Dynamic leaching behavior of geogenic As in soils after cement-based stabilization/solidification.

Science.gov (United States)

Li, Jiang-Shan; Wang, Lei; Tsang, Daniel C W; Beiyuan, Jingzi; Poon, Chi Sun

2017-12-01

Cement-based stabilization/solidification (S/S) is a practical treatment approach for hazardous waste with anthropogenic As sources; however, its applicability for geogenic As-containing soil and the long-term leaching potential remain uncertain. In this study, semi-dynamic leaching test was performed to investigate the influence of S/S binders (cement blended with fuel ash (FA), furnace bottom ash (FBA), or ground granulated blast furnace slag (GGBS)) on the long-term leaching characteristics of geogenic As. The results showed that mineral admixtures with higher Ca content and pozzolanic activity were more effective in reducing the leached As concentrations. Thus, cement blended with FBA was inferior to other binders in suppressing the As leaching, while 20% replacement of ordinary Portland cement by GGBS was considered most feasible for the S/S treatment of As-containing soils. The leachability of geogenic As was suppressed by the encapsulation effect of solidified matrix and interlocking network of hydration products that were supported by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) results. The long-term leaching of geogenic As from the monolithic samples was diffusion-controlled. Increasing the Ca content in the samples led to a decrease in diffusion coefficient and an increase in feasibility for "controlled utilization" of the S/S-treated soils.

Stabilization of marly soils with portland cement

Science.gov (United States)

Piskunov, Maksim; Karzin, Evgeny; Lukina, Valentina; Lukinov, Vitaly; Kholkin, Anatolii

2017-10-01

Stabilization of marlous soils with Portland cement will increase the service life of motor roads in areas where marl is used as a local road construction material. The result of the conducted research is the conclusion about the principal possibility of stabilization of marlous soils with Portland cement, and about the optimal percentage of the mineral part and the binding agent. When planning the experiment, a simplex-lattice plan was implemented, which makes it possible to obtain a mathematical model for changing the properties of a material in the form of polynomials of incomplete third order. Brands were determined for compressive strength according to GOST 23558-94 and variants of stabilized soils were proposed for road construction.

Mechanism for the stabilization/solidification of arsenic-contaminated soils with Portland cement and cement kiln dust.

Science.gov (United States)

Yoon, In-Ho; Moon, Deok Hyun; Kim, Kyoung-Woong; Lee, Keun-Young; Lee, Ji-Hoon; Kim, Min Gyu

2010-11-01

In this study, the mechanism for the stabilization/solidification (S/S) of arsenic (As)-contaminated soils with Portland cement (PC), and cement kiln dust (CKD) using 1 N HCl extraction fluid, X-ray powder diffraction (XRPD), X-ray absorption near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS) spectroscopy was investigated. The degree of As immobilization after stabilization was assessed using a 1 N HCl extraction on the basis of the Korean Standard Test (KST). After 1 day of curing with 30 wt% PC and 7 days of curing with 50 wt% CKD, the concentration of As leached from the amended soils was less than the Korean countermeasure standard (3 mg L(-1)). The As concentrations in the leachate treated with PC and CKD were significantly decreased at pH > 3, indicating that pH had a prevailing influence on As mobility. XRPD results indicated that calcium arsenite (Ca-As-O) and sodium calcium arsenate hydrate (NaCaAsO(4).7.5H(2)O) were present in the PC- and CKD-treated slurries as the key phases responsible for As(III) and As(V) immobilization, respectively. The XANES spectroscopy confirmed that the As(III) and As(V) oxidation states of the PC and CKD slurry samples were consistent with the speciated forms in the crystals identified by XRPD. EXAFS spectroscopy showed As-Ca bonding in the As(III)-PC and As(III)-CKD slurries. The main mechanism for the immobilization of As-contaminated soils with PC and CKD was strongly associated with the bonding between As(III) or As(V) and Ca. Copyright 2010 Elsevier Ltd. All rights reserved.

A Model of Thermal Conductivity for Planetary Soils. 2; Theory for Cemented Soils

Science.gov (United States)

Piqueux, S.; Christensen, P. R.

2009-01-01

A numerical model of heat conduction through particulate media made of spherical grains cemented by various bonding agents is presented. The pore-filling gas conductivity, volume fraction, and thermal conductivity of the cementing phase are tunable parameters. Cement fractions thermal conductivity. A significant conductivity increase (factor 3-8) is observed for bond fractions of 0.01 to 1% in volume. In the 1 to 15% bond fraction domain, the conductivity increases continuously but less intensely (25-100% conductivity increase compared to a 1% bond system). Beyond 15% of cements, the conductivity increases vigorously and the bulk conductivity rapidly approaches that of bedrock. The composition of the cements (i.e. conductivity) has little influence on the bulk thermal inertia of the soil, especially if the volume of bond thermal inertia (200-600 J s(0.5)/sq m/K) has long been hypothesized to be associated with a duricrust. The fraction of cement required to fit the thermal data is less than approx.1-5% by volume. This small amount of material is consistent with orbital observations, confirming that soil cementation is an important factor controlling the thermal inertia of the Martian surface

Reliability estimate of unconfined compressive strength of black cotton soil stabilized with cement and quarry dust

Directory of Open Access Journals (Sweden)

Dayo Oluwatoyin AKANBI

2017-06-01

Full Text Available Reliability estimates of unconfined compressive strength values from laboratory results for specimens compacted at British Standard Light (BSLfor compacted quarry dust treated black cotton soil using cement for road sub – base material was developed by incorporating data obtained from Unconfined compressive strength (UCS test gotten from the laboratory test to produce a predictive model. Data obtained were incorporated into a FORTRAN-based first-order reliability program to obtain reliability index values. Variable factors such as water content relative to optimum (WRO, hydraulic modulus (HM, quarry dust (QD, cement (C, Tri-Calcium silicate (C3S, Di-calcium silicate (C2S, Tri-Calcium Aluminate (C3A, and maximum dry density (MDD produced acceptable safety index value of1.0and they were achieved at coefficient of variation (COV ranges of 10-100%. Observed trends indicate that WRO, C3S, C2S and MDD are greatly influenced by the COV and therefore must be strictly controlled in QD/C treated black cotton soil for use as sub-base material in road pavements. Stochastically, British Standard light (BSL can be used to model the 7 days unconfined compressive strength of compacted quarry dust/cement treated black cotton soil as a sub-base material for road pavement at all coefficient of variation (COV range 10 – 100% because the safety index obtained are higher than the acceptable 1.0 value.

Influence of industrial solid waste addition on properties of soil-cement bricks

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F. B. Siqueira

Full Text Available Abstract The reuse of pollutant solid wastes produced in distinct industrial activities (avian eggshell waste and welding flux slag waste as a source of alternative raw material for producing soil-cement bricks for civil construction was investigated. Soil-cement bricks containing up to 30 wt% of industrial solid waste were uniaxially pressed and cured for 28 days. Special emphasis is given on the influence of solid waste addition on the technical properties (as such volumetric shrinkage, water absorption, bulk density, durability, and compressive strength, microstructure and mineral phases of soil-cement bricks. Microstructural evolution was evaluated via confocal microscopy. The experimental results showed that the solid wastes behave as charge material and influenced both technical properties and microstructure of the soil-cement bricks. It was found that up to 15 wt% of welding flux slag waste and up to 30 wt% of avian eggshell waste could be added into the soil-cement bricks for use as building material.

A Model of Thermal Conductivity for Planetary Soils. 2; Theory for Cemented Soils

Science.gov (United States)

Piqueux, S.; Christensen, P. R.

2009-01-01

A numerical model of heat conduction through particulate media made of spherical grains cemented by various bonding agents is presented. The pore-filling gas conductivity, volume fraction, and thermal conductivity of the cementing phase are tunable parameters. Cement fractions duricrust. The fraction of cement required to fit the thermal data is less than approx.1-5% by volume. This small amount of material is consistent with orbital observations, confirming that soil cementation is an important factor controlling the thermal inertia of the Martian surface

A model of thermal conductivity for planetary soils: 2. Theory for cemented soils

Science.gov (United States)

Piqueux, S.; Christensen, P. R.

2009-09-01

A numerical model of heat conduction through particulate media made of spherical grains cemented by various bonding agents is presented. The pore-filling gas conductivity, volume fraction, and thermal conductivity of the cementing phase are tunable parameters. Cement fractions duricrust. The fraction of cement required to fit the thermal data is less than ˜1-5% by volume. This small amount of material is consistent with orbital observations, confirming that soil cementation is an important factor controlling the thermal inertia of the Martian surface.

Stabilization treatment of soft subgrade soil by sewage sludge ash and cement.

Science.gov (United States)

Chen, Li; Lin, Deng-Fong

2009-02-15

In this study, incinerated sewage sludge ash (ISSA) is mixed with cement in a fixed ratio of 4:1 for use as a stabilizer to improve the strength of soft, cohesive, subgrade soil. Five different ratios (in wt%: 0%, 2%, 4%, 8%, and 16%) of ISSA/cement admixture are mixed with cohesive soil to make soil samples. In order to understand the influences of admixtures on the soil properties, tests of the pH value, Atterberg limits, compaction, California bearing ratio (CBR), unconfined compressive strength, and triaxial compression were performed on those samples. The study shows that the unconfined compressive strength of specimens with the ISSA/cement addition was improved to approximately 3-7 times better than that of the untreated soil; furthermore, the swelling behavior was also effectively reduced as much as 10-60% for those samples. In some samples, the ISSA/cement additive improved the CBR values by up to 30 times that of untreated soil. This suggests that ISSA/cement has many potential applications in the field of geotechnical engineering.

Remediation of contaminated soil by cement treatment

International Nuclear Information System (INIS)

Dimovic, S.

2004-01-01

This manuscript presents the most applicable remedial technologies for contaminated soil with focus on cement stabilisation/solidification treatment. These technologies are examined in the light of soil contamination with depleted uranium in the large area of south Serbia,after Nato bombing 1999. (author) [sr

Geophysical and Geotechnical Characterization of Beta-1,3/1,6-glucan Biopolymer treated Soil

Science.gov (United States)

Chang, I.; Cho, G.

2012-12-01

Bacteria or microbes in soil excrete hydrocarbon (e.g. polysaccharide) by-products which are called biopolymers. These biopolymers (or sometime biofilms) recently begun to make a mark on soil erosion control, aggregate stabilization, and drilling enhancement. However, the biological effect on soil behavior (e.g. bio-clogging or bio-cementation) has been poorly understood. In this study, the bio-cementation and bio-clogging effect induced by the existence of β-1,3/1,6-glucan biopolymers in soil were evaluated through a series of geophysical and geotechnical characterization tests in laboratory. According to the experimental test results, as the β-1,3/1,6-glucan content in soil increases, the compressive strength and shear wave velocity increase (i.e., bio-cementation) while the hydraulic conductivity decreases (i.e., bio-clogging) but the electrical conductivity increases due to the high electrical conductivity characteristic of β-1,3/1,6-glucan fibers. Coefficient of consolidation variation with the increases of β-1,3/1,6-glucan content in soil. SEM image of β-1,3/1,6-glucan treated soil. Fibers are form matices with soil particles.

Industrial Wastes as Auxiliary Additives to Cement/Lime Stabilization of Soils

OpenAIRE

James, Jijo; Pandian, P. Kasinatha

2016-01-01

Chemical stabilization involves the use of chemical agents for initiating reactions within the soil for modification of its geotechnical properties. Cement and lime stabilization have been the most common stabilization methods adopted for soil treatment. Cement stabilization results in good compressive strengths and is preferred for cohesionless to moderately cohesive soil but loses effectiveness when the soil is highly plastic. Lime stabilization is the most preferred method for plastic clay...

Effect of cement dust pollution on certain physical parameters of maize crop and soils

Energy Technology Data Exchange (ETDEWEB)

Parthasarathy, S; Arunachalam, N; Natarajan, K; Oblisami, G; Rangaswami, G

1975-04-01

A study was undertaken in the fields near a cement factory where the cement dust is the prime pollutant to the field crops and soils. Cement dust deposit varied with the distance from the kiln and fourth and fifth leaves of maize had comparatively more dust than the first three leaves from the top. The cement dust deposited plants showed a suppression in most of the characters like leaf size, number and size of cobs and plant height when compared to plants in non-polluted fields. On comparison with the physical characters of the soils from the control field the soil from cement dust polluted field showed a decrease in water holding capacity and pore space while thermal conductivity and specific heat were more. Artificial mixtures of red and black soils with cement dust showed similar trend as those of the field sample, the black soil being affected more seriously than the red soil.

Influence of Rice Husk Ash and Clay in Stabilization of Silty Soils Using Cement

OpenAIRE

Widjajakusuma Jack; Winata Hendo

2017-01-01

Soil stabilization is needed to enhance the strength of the soil. One popular method of soil stabilization is using cement. Due to the environmental issue, it is a need to reduce the application of cement and/or to replace partially the cement with other environmental-friendly compounds. One of these compounds is rice husk ash (RSA), which is agricultural wastes. The objective of this paper is to study the influence of RSA and clay as partial replacement to cement in soil stabilization of sil...

Study of the stabilization of a loamy soil with addition of cement

Directory of Open Access Journals (Sweden)

Jonas Alexandre

2010-05-01

Full Text Available The use of soil-cement bricks is considered a cheaper constructive method than the conventional (ceramic block or concrete, because one of the raw materials is abundant (the soil. The objective of the present work was to identify the soil of the “Codin” area, in the municipality of Campos of Goytacazes - RJ. After this identification, it was possible to determine the best line for the production of soil-cement, in the 9,5x 10x5 cm format, with lines containing the addition of 5% and 10% of cement in volume.

Rice husk ash (RHA) as a partial cement replacement in modifying peat soil properties

Science.gov (United States)

Daud, Nik Norsyahariati Nik; Daud, Mohd Nazrin Mohd; Muhammed, Abubakar Sadiq

2018-02-01

This paper describes the effect of rice husk ash (RHA) and ordinary Portland cement (OPC) as a potential binder for modifying the properties of peat soil. The amounts RHA and OPC added to the peat soil sample, as percentage of the dry soil mass were in the range of 10-15% and 15%, respectively. Observations were made for the changes in the properties of the soil such as maximum dry density (MDD), optimum moisture content (OMC) and shear strength. Scanning Electron Micrograph-Energy Dispersive X-Ray (SEM-EDX) test were also conducted to observe the microstructure of treated and untreated peat soil. The results show that the modified soil of MDD and OMC values are increased due to the increment amount of binder material. Shear strength values of modified peat showing a good result by assuming that it is relative to the formation of major reaction products such as calcium silicate hydrate (C-S-H). The presence of C-S-H formation is indicated by the results produced from microstructural analysis of peat before and after modification process. This depicts the potential usage of RHA as a partial cement replacement in peat soil which is also improving its engineering properties.

Stabilization techniques for reactive aggregate in soil-cement base course : technical summary.

Science.gov (United States)

2003-01-01

The objectives of this research are 1) to identify the mineralogical properties of soil-cement bases which have heaved or can potentially heave, 2) to simulate expansion of cement-stabilized soil in the laboratory, 3) to correlate expansion with the ...

Enhancing the compressive strength of landfill soil using cement and bagasse ash

Science.gov (United States)

Azim, M. A. M.; Azhar, A. T. S.; Tarmizi, A. K. A.; Shahidan, S.; Nabila, A. T. A.

2017-11-01

The stabilisation of contaminated soil with cement and agricultural waste is a widely applied method which contributes to the sustainability of the environment. Soil may be stabilised to increase strength and durability or to prevent erosion and other geotechnical failure. This study was carried out to evaluate the compressive strength of ex-landfill soil when cement and bagasse ash (BA) are added to it. Different proportions of cement (5%, 10%, 15% and 20%) was added to sample weights without BA. On the other hand, the cement in a different batch of sample weights was replaced by 2.5%, 5%, 7.5% and 10% of BA. All samples were allowed to harden and were cured at room temperature for 7, 14 and 28 days respectively. The strength of the contaminated soil was assessed using an unconfined compressive strength test (UCS). The laboratory tests also included the index properties of soil, cement and bagasse ash in raw form. The results indicated that the samples with cement achieved the highest compressive strength measuring 4.39 MPa. However, this study revealed that the use of bagasse ash produced low quality products with a reduction in strength. For example, when 5% of cement was replaced with 5% ash, the compressive strength decreased by about 54% from 0.72 MPa to 0.33 MPa. Similarly, the compressive strength of each sample after a curing period of 28 days was higher compared to samples cured for 7 and 14 days respectively. This is proved that a longer curing period is needed to increase the compressive strength of the samples.

Influence of zeolite and cement additions on mechanical behavior of sandy soil

Directory of Open Access Journals (Sweden)

Hossein Mola-Abasi

2016-10-01

Full Text Available It is well known that the cemented sand is one of economic and environmental topics in soil stabilization. In this instance, a blend of sand, cement and other materials such as fiber, glass, nanoparticle and zeolite can be commercially available and effectively used in soil stabilization in road construction. However, the influence and effectiveness of zeolite on the properties of cemented sand systems have not been completely explored. In this study, based on an experimental program, the effects of zeolite on the characteristics of cemented sands are investigated. Stabilizing agent includes Portland cement of type II and zeolite. Results show the improvements of unconfined compressive strength (UCS and failure properties of cemented sand when the cement is replaced by zeolite at an optimum proportion of 30% after 28 days. The rate of strength improvement is approximately between 20% and 78%. The efficiency of using zeolite increases with the increases in cement amount and porosity. Finally, a power function of void-cement ratio and zeolite content is demonstrated to be an appropriate method to assess UCS of zeolite-cemented mixtures.

INTERACTION OF SOIL-CEMENT PILE SUPPORTING STRUCTURES WITH THE BODY OF A LANDSLIDE

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D. Y. Ihnatenko

2017-10-01

Full Text Available Purpose. Analysis and comparison of the landslide slope finite element model calculation results of the appliance of soil-cement piles, depending on the variation of the retaining structure rigidity, makes it possible to evaluate the effectiveness of their application and the cooperative work of piles with the displacement body. It also makes it possible to make a conclusion about the advantages of using this anti-landslide protection method of the slope. Methodology. Analysis of geomorphological data obtained from the results of laboratory studies of soils on the slope section is considered. Creation of a three-dimensional finite-element slope model according to the constructed sections and depths of the soil layers. Calculation of the nonlinear problem of finite element modeling of the slope with applying of soil-cement piles of various rigidity. Findings. The obtained results of calculating the finite element model of the landslide slope, and the analysis of the stress-strain state of the construction with soil-cement piles has been carried out. Originality. Despite the widespread of using soil-cement piles as enclosing structures for the construction of foundation pits and reinforcement of foundations of emergency structures, special attention should be paid to the study of the expediency of using soil-cement retaining pile structures on landslide areas. Practical value. It is known that soil-cement retaining piles are expediently in use as a protective element, which interacts quite well with the ground environment due to its structure of the initial material. Using of modern computer programs of finite element modeling makes it possible to calculate the efficiency of the use of soil-cement piles and to determine the parameters of the necessary retaining structure according to the given geological structure of the slope, and also, depending on its shape and the physical characteristics of the soils, to compare the performance of different

Fracture analysis of cement treated demolition waste using a lattice model

NARCIS (Netherlands)

Xuan, D.; Schlangen, H.E.J.G.; Molenaar, A.A.A.; Houben, L.J.M.

2013-01-01

Fracture properties of cement treated demolition waste were investigated using a lattice model. In practice the investigated material is applied as a cement treated road base/subbase course. The granular aggregates used in this material were crushed recycled concrete and masonry. This results in six

Compound soil-tyre chips modified by cement as a road construction material

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Panu Promputthangkoon

2013-10-01

Full Text Available This research attempts to overcome the two problems of low-quality soil and a growing number of discarded tyres bymixing low-CBR soil with recycled tyre chips. The compound soil-tyre chips was then stabilised by Portland cement with theaim of using them as a new material in road construction in order to reduce the occurrence of shrinkage cracks. To achievethe purposes of this research three standard geotechnical testing programmes were employed: (1 modified compaction tests,(2 California Bearing Ratio tests (CBR, and (3 unconfined compression tests. The modified compaction test results provedthat for the mixtures having very low tyre chips and cement content, the behaviour is very complex. It was also observed thatthe greater the percentage of rubber added the lower the global density. However, this is predictable as the specific gravityof the rubber is much lower than that of the soil. For the relationship between the optimum moisture content (OMC and thecement content, it was observed that there is no clear pattern.For the specimens having no cement added, the CBR for unsoaked specimens was observed to be greater than that forsoaked specimens. However, when the cement was introduced the CBR test showed that the resistance to penetration for thesoaked specimens was significantly greater, indicating the effects of cement added on the strength. In addition, it was foundthat the CBR values for both soaked and unsoaked specimens gradually increased with the increase of cement content.Lastly, the unconfined compressive strength progressively increased with the increased percentage of cement.

Effect of soil stabilized by cement on dynamic response of machine foundations

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Al-Wakel Saad

2018-01-01

Full Text Available Machine foundations require significant attention from designers. The main goal of the design of machine foundation is to limit the amplitude displacement and not disturb the people who work near the machine. In some cases, if the design of machine foundations does not satisfy the acceptable value of the dynamic response (such as maximum amplitude of displacement, the stabilization of soil under the machine foundation may be used to decrease the amplitude of displacement. This paper outlines effect of stabilized soil under the foundation by cement on the displacement response of machine foundations. Three-dimensional analyses by using finite element method are carried out to investigate the effect of depth of stabilized layer with different percentage of cement content on the dynamic response of the machine foundation. In addition, the effect of area stabilized by cement material on the dynamic response of machine foundation is investigated. The results shown that, the dynamic response of machine foundations generally decreases with increasing the depth of soil layer stabilized with cement. A significant decrease in the displacement of machine foundations is occurred for the stabilized soil layer with a depth of two times of the width of foundation, and the optimum percentage of cement for stabilizing is 6%.

Study of the stabilization of a loamy soil with addition of cement

OpenAIRE

Jonas Alexandre; Maria da Glória Alves; Thiago Vicente Lima

2010-01-01

The use of soil-cement bricks is considered a cheaper constructive method than the conventional (ceramic block or concrete), because one of the raw materials is abundant (the soil). The objective of the present work was to identify the soil of the “Codin” area, in the municipality of Campos of Goytacazes - RJ. After this identification, it was possible to determine the best line for the production of soil-cement, in the 9,5x 10x5 cm format, with lines containing the addition of 5% and 10% of ...

Incorporation of bitumen and calcium silicate in cement and lime stabilized soil blocks

Science.gov (United States)

Kwan, W. H.; Cheah, C. B.; Ramli, M.; Al-Sakkaf, Y. K.

2017-04-01

Providing affordable housing is the most critical problem in many of the developing countries. Using earth materials in building construction is one of the feasible methods to address this issue and it can be a way towards sustainable construction as well. However, the published information on the stabilized soil blocks is limited. Therefore, the present study is conducted to examine the characterization of the soils and engineering properties of the stabilized soil blocks. Four types of stabilizer were used in the study, namely; cement, slaked lime, bitumen emulsion and calcium silicate. Cement and slaked lime were added at different percentages in the range of 5% to 15%, with interval of 2.5%. The percentage was determined based on weight of soil. Meanwhile, bitumen emulsion and calcium silicate were incorporated at various percentages together with 10% of cement. Dosage of bitumen emulsion is in the range of 2% to 10% at interval of 2% while calcium silicate was incorporated at 0.50%, 0.75%, 1.00%, 1.25%, 1.50% and 2.00%. Results show that cement is the most viable stabilizer for the soil block among all stabilizers in this study. The bulk density, optimum moisture content and compressive strengths were increased with the increasing cement content. The most suitable cement content was 10% added at moisture content of 12%. Lime, bitumen and calcium contents were recommended at 5.0%, 6.0% and 1.25%, respectively.

Spectroscopy of Loose and Cemented Sulfate-Bearing Soils: Implications for Duricrust on Mars

Science.gov (United States)

Cooper, Christopher D.; Mustard, John F.

2002-07-01

The goal of this work is to determine the spectroscopic properties of sulfate in martian soil analogs over the wavelength range 0.3 to 25 μm (which is relevant to existing and planned remotely sensed data sets for Mars). Sulfate is an abundant component of martian soil (up to 9% SO 3 by weight) and apparently exists as a particulate in the soil but also as a cement. Although previous studies have addressed the spectroscopic identity of sulfates on Mars, none have used laboratory mixtures of materials with sulfates at the abundances measured by landed spacecraft, nor have any works considered the effect of salt-cementation on spectral properties of soil materials. For this work we created mixtures of a palagonitic soil (JSC Mars-1) and sulfates (MgSO 4 and CaSO 4·2H 2O). The effects of cementation were determined and separated from the effects of packing and hydration by measuring the samples as loose powders, packed powders, cemented materials, and disaggregated materials. The results show that the presence of particulate sulfate is best observed in the 4-5 μm region. Soils cemented with sulfate exhibit a pronounced restrahlen band between 8 and 9 μm as well as well-defined absorptions in the 4-5 μm region. Cementation effects are distinct from packing effects and disaggregation of cemented samples rapidly diminishes the strength of the restrahlen bands. The results of this study show that sulfate in loose materials is more detectable in the near infrared (4-5 μm) than in the thermal infrared (8-9 μm). However, cemented materials are easily distinguished from loose mixtures in the thermal infrared because of the high values of their absorption coefficient in this region. Together these results suggest that both wavelength regions are important for determining the spatial extent and physical form of sulfates on the surface of Mars.

A rapid method for soil cement design : Louisiana slope value method.

Science.gov (United States)

1964-03-01

The current procedure used by the Louisiana Department of Highways for laboratory design of cement stabilized soil base and subbase courses is taken from standard AASHO test methods, patterned after Portland Cement Association criteria. These methods...

Comparative Response of Four Pedogenic Soil Materials to Cement ...

African Journals Online (AJOL)

A comparative response of four Pedogenic soil materials to cement stabilization was investigated. The studies focused on the compaction characteristics, the unconfined sompressive strength and the California bearing ratio of the samples. The results obtained show that soil materials from Maiduguri responded favorably to ...

Stabilisation of clayey soils with high calcium fly ash and cement

Energy Technology Data Exchange (ETDEWEB)

S. Kolias; V. Kasselouri-Rigopoulou; A. Karahalios [National Technical University of Athens, Athens (Greece)

2005-02-01

The effectiveness of using high calcium fly ash and cement in stabilising fine-grained clayey soils (CL,CH) was investigated in the laboratory. Strength tests in uniaxial compression, in indirect (splitting) tension and flexure were carried out on samples to which various percentages of fly ash and cement had been added. Modulus of elasticity was determined at 90 days with different types of load application and 90-day soaked CBR values are also reported. Pavement structures incorporating subgrades improved by in situ stabilisation with fly ash and cement were analyzed for construction traffic and for operating traffic. These pavements are compared with conventional flexible pavements without improved subgrades and the results clearly show the technical benefits of stabilising clayey soils with fly ash and cement. In addition TG-SDTA and XRD tests were carried out on certain samples in order to study the hydraulic compounds, which were formed.

Effect of cement injection on sandy soil slope stability, case study: slope in Petang district, Badung regency

Science.gov (United States)

Arya, I. W.; Wiraga, I. W.; GAG Suryanegara, I.

2018-01-01

Slope is a part of soil topography formed due to elevation difference from two soil surface. Landslides is frequently occur in natural slope, it is because shear force is greater than shear strength in the soil. There are some factor that influence slope stability such as: rain dissipation, vibration from earthquake, construction and crack in the soil. Slope instability can cause risk in human activity or even threaten human lives. Every years in rainy season, landslides always occur in Indonesia. In 2016, there was some landslide occurred in Bali. One of the most damaging is landslide in Petang district, Badung regency. This landslide caused main road closed entirely. In order to overcome and prevent landslide, a lot of method have been practiced and still looking for more sophisticated method for forecasting slope stability. One of the method to strengthen soil stability is filling the soil pores with some certain material. Cement is one of the material that can be used to fill the soil pores because when it is in liquid form, it can infiltrate into soil pores and fill the gap between soil particles. And after it dry, it can formed a bond with soil particle so that soil become stronger and the slope as well. In this study, it will use experimental method, slope model in laboratory to simulate a real slope behavior in the field. The first model is the slope without any addition of cement. This model will be become a benchmark for the other models. The second model is a slope with improved soil that injects the slope with cement. Injection of cement is done with varying interval distance of injection point is 5 cm and 10 cm. Each slope model will be given a load until the slope collapses. The slope model will also be analyzed with slope stability program. The test results on the improved slope models will be compared with unimproved slope. In the initial test will consist of 3 model. First model is soil without improvement or cement injection, second model is soil

Stabilization/solidification of selenium-impacted soils using Portland cement and cement kiln dust

International Nuclear Information System (INIS)

Moon, Deok Hyun; Grubb, Dennis G.; Reilly, Trevor L.

2009-01-01

Stabilization/solidification (S/S) processes were utilized to immobilize selenium (Se) as selenite (SeO 3 2- ) and selenate (SeO 4 2- ). Artificially contaminated soils were prepared by individually spiking kaolinite, montmorillonite and dredged material (DM; an organic silt) with 1000 mg/kg of each selenium compound. After mellowing for 7 days, the Se-impacted soils were each stabilized with 5, 10 and 15% Type I/II Portland cement (P) and cement kiln dust (C) and then were cured for 7 and 28 days. The toxicity characteristic leaching procedure (TCLP) was used to evaluate the effectiveness of the S/S treatments. At 28 days curing, P doses of 10 and 15% produced five out of six TCLP-Se(IV) concentrations below 10 mg/L, whereas only the 15% C in DM had a TCLP-Se(IV) concentration 3 .H 2 O) and selenate substituted ettringite (Ca 6 Al 2 (SeO 4 ) 3 (OH) 12 .26H 2 O), respectively.

Compressibility of soft Iraqi soil stabilized with traditional Iraqi stabilizers (cement and lime

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Baqir Husam

2018-01-01

Full Text Available This study shows an improvement of two types of clay soil brought from different parts of Iraq. The first soil (A from Al - Zaafaraniya site in Baghdad governorate. The second soil (B from Garma Ali site in the Al Basra governorate, Iraq. Soft clayey soils were treated by a combination of sulphate resistance Portland cement (PC and Quicklime (LQ to modify and stability. PC was added in percentages of 2,4,6,8 and 10%, as well as, LQ was added to 2 and 4%, of dry weight. Laboratory tests to determine specific gravity, Atterbergs limits and standard proctor test were conducted. Also, the main objective of this research is the concentrating on compression ratio (CR, the Rebound (Swelling ratio (RR and the stiffness during the modulus of elasticity (Es for treated and natural soils procreation from consolidation test. The results from laboratory tests shows high ability on the enhancing in terms of reduction in plasticity index (greatly increased workability, reduction in compression ratio (CR, reduction in the Rebound (Swelling ratio (RR, increase in the modulus of elasticity (Es. The change in moisture-density relationships resulting in lower maximum dry densities, higher optimum water content, and less variation of dry density from the maximum over a much wider range of water contents.

Development of low thermal mass cement-sand block utilizing peat soil and effective microorganism

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Irham Hameeda Mohamad Idris

2018-06-01

Full Text Available The development of low thermal mass cement-sand block by incorporating peat soil and Effective Microorganism (EM was studied systematically. In total, seven mixtures of cement-sand block targeted at a 28-days compressive strength of 7 MPa are designed. One control sample is made with a water/cement ratio (w/c of 0.5, three mixes using 3%, 6% and 10% peat soil replacing sand and three mixes using 10%, 20% and 30% EM replacing water. Modified blocks with 6% of peat soil and 30% of EM are the most optimum blocks to be used in the construction of masonry as they successfully reduced the thermal conductivity of the blocks with the value of 1.275 W/mK and 1.792 W/mK respectively when being compared to the thermal conductivity of the control sample which is 2.400 W/mK. Besides, they are also able to achieve higher strength than the desired compressive strength which is 7 MPa. The compressive strength of the samples with 6% of peat soil is 16.48 MPa at 28-days while 30.39 MPa for samples with 30% of EM. On the other hand, the water absorption rate of samples with 6% of peat soil is 7.6% while 6.1% for samples with 30% EM and both are okay since their rate of water absorption is lower than 20%. In conclusion, the addition of peat soil and EM in the cement-sand mix show promising performance as a low cost material to produce low thermal mass cement-sand block. Keywords: Effective microorganism, Peat soil, Thermal conductivity, Cement brick

Stabilization/solidification of lead-contaminated soil using cement and rice husk ash.

Science.gov (United States)

Yin, Chun-Yang; Mahmud, Hilmi Bin; Shaaban, Md Ghazaly

2006-10-11

This paper presents the findings of a study on solidification/stabilization (S/S) of lead-contaminated soil using ordinary Portland cement (OPC) and rice husk ash (RHA). The effects of varying lead concentrations (in the form of nitrates) in soil samples on the physical properties of their stabilized forms, namely unconfined compressive strength (UCS), setting times of early mixtures and changes in crystalline phases as well as chemical properties such as leachability of lead, pH and alkalinity of leachates are studied. Results have indicated that usage of OPC with RHA as an overall binder system for S/S of lead-contaminated soils is more favorable in reducing the leachability of lead from the treated samples than a binder system with standalone OPC. On the other hand, partial replacement of OPC with RHA in the binder system has reduced the UCS of solidified samples.

geometric models for lateritic soil stabilized with cement

African Journals Online (AJOL)

user

stabilized lateritic soil and also to develop geometric models. The compaction, California .... on how effective limited field data are put to use in decision-making. ..... silicates was described as the most important phase of cement and the ...

Industrial Wastes as Auxiliary Additives to Cement/Lime Stabilization of Soils

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Jijo James

2016-01-01

Full Text Available Chemical stabilization involves the use of chemical agents for initiating reactions within the soil for modification of its geotechnical properties. Cement and lime stabilization have been the most common stabilization methods adopted for soil treatment. Cement stabilization results in good compressive strengths and is preferred for cohesionless to moderately cohesive soil but loses effectiveness when the soil is highly plastic. Lime stabilization is the most preferred method for plastic clays; however, it proves to be ineffective in sulphate rich clays and performs poorly under extreme conditions. With such drawbacks, lots of researches have been undertaken to address the issues faced with each stabilization method, in particular, the use of solid wastes for soil stabilization. Solid waste reuse has gained high momentum for achieving sustainable waste management in recent times. Research has shown that the use of solid wastes as additives with and replacement for conventional stabilizers has resulted in better results than the performance of either individually. This review provides insight into some of the works done by earlier researchers on lime/cement stabilization with industrial wastes as additives and helps to form a sound platform for further research on industrial wastes as additives to conventional stabilizers.

Evaluation of Carbonation Effects on Cement-Solidified Contaminated Soil Used in Road Subgrade

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Yundong Zhou

2018-01-01

Full Text Available Cement solidification/stabilization is widely used towards contaminated soil since it has a low price and significant improvement for the structural capacity of soil. To increase the usage of the solidified matrix, cement-solidified contaminated soil was used as road subgrade material. In this study, carbonation effect that reflected the durability on strength characteristics of cement-solidified contaminated soil and the settlement of pavement were evaluated through experimental and numerical analysis, respectively. According to results, compressive strengths of specimens with 1% Pb(II under carbonation and standard curing range from 0.44 MPa to 1.17 MPa and 0.14 MPa to 2.67 MPa, respectively. The relatively low strengths were attributed to immobilization of heavy metal, which consumed part of SiO2, Al2O3, and CaO components in the cement or kaolin and reduced the hydration and pozzolanic reaction materials. This phenomenon further decreased the strength of solidified soils. The carbonation depth of 1% Cu(II or Zn(II contaminated soils was 18 mm, which significantly increased with the increase of curing time and contamination concentration. Furthermore, the finite element calculation results showed that surface settlements decreased with the increase of modulus of subgrade and the distance away from the center. At the center, the pavement settlement was proportional to the level of traffic load.

Chemical Modification of Uniform Soils and Soils with High/Low Plasticity Index

OpenAIRE

Li, Xuanchi; Tao, Fei; Bobet, Antonio

2015-01-01

Lime and/or cement are used to treat weak subgrade soils during construction of highways. These chemicals are mixed with the soil to improve its workability, compactability and engineering properties. INDOT (Indiana Department of Transportation) has been using chemical modification of native soils for the past 20 years. In fact, 90% of current subgrade is treated, typically with quick lime, lime byproducts or cement. For pavement design, it is customary to not include any improvement of the s...

Characterization of PCC Cement by Addition of Napa Soil from Subdistrict Sarilamak 50 Kota District as Alternative Additional Material for Semen Padang

Science.gov (United States)

Mawardi, M.; Deyundha, D.; Zainul, R.; Zalmi P, R.

2018-04-01

The study has been conducted to determine characteristics of the portland composite cement by the addition of napa soil from Sarilamak subdistrict, 50 Kota District as an alternative additional material at PT. Semen Padang. Napa soil is a natural material highly containing silica and alumina minerals so that it can be one of material in producing cement. This study aims to determine the effect of napa soil on the quality of portland composite cement. Napa soil used in the variation compositions 0%, 4%, 8%, 12% and 16%, for control of cement used 8 % of pozzolan and 0 % of napa soil. Determination of cement quality by testing cement characteristics include blaine test, sieving, lost of ignition or LOI, insoluble residue, normal consistency, setting time and compressive strength. Cement was characterized using XRF. Fineness of cement decreases with the addition of napa soil. Lost of Ignition of cement decreased, while the insoluble residue increased with the addition of napa soil. Normal consistency of cement increasing, so does initial setting time and final setting time of cement. While the resultant compressive strength decreases with the addition of napa soil on 28 days, 342, 325, 307, 306, and 300 kg / cm2.

Influence of industrial solid waste addition on properties of soil-cement bricks

OpenAIRE

Siqueira, F. B.; Amaral, M. C.; Bou-Issa, R. A.; Holanda, J. N. F.

2016-01-01

Abstract The reuse of pollutant solid wastes produced in distinct industrial activities (avian eggshell waste and welding flux slag waste) as a source of alternative raw material for producing soil-cement bricks for civil construction was investigated. Soil-cement bricks containing up to 30 wt% of industrial solid waste were uniaxially pressed and cured for 28 days. Special emphasis is given on the influence of solid waste addition on the technical properties (as such volumetric shrinkage, wa...

Cement conditioning of waste materials and polluted soil using the GEODUR process

International Nuclear Information System (INIS)

Brocdersen, K.; Hjelmar, O.; Mortonsen, S.

1991-01-01

In this paper two areas of application of the GEODUR additive in cement stabilization of waste materials have been investigated: stabilization of radioactive contaminated soil and stabilization of municipal solid waste incinerator ash. Preliminary experimental work on a clayey soil contaminated with radioactive cesium and strontium has indicated that the GEODUR process is a technically feasible method for soil solidification. The retarding effects of humic materials in the soil are eliminated by the additive even at low cement contents. The solidified soil is not particularly strong, but that satisfactory water permeability. Retention of cesium is reasonably good, but not as good as for the untreated soil. Retention of strontium is not good but is considerably improved by carbonation. The volume stability during permanent immersion of the solidified products in water is satisfactory, but crack formation during dryout cannot be excluded

Interrelationships among geotechnical and leaching properties of a cement-stabilized contaminated soil.

Science.gov (United States)

Kogbara, Reginald B

2017-01-28

Relationships among selected performance properties have been established using experimental data from a cement-stabilized mixed contaminated soil. The sandy soil was spiked with 3,000 mg/kg each of Cd, Cu, Pb, Ni and Zn, and 10,000 mg/kg of diesel. It was then treated with 5%, 10%, 15%, and 20% dosages of Portland cement. Different water contents were considered for lower dosage mixes. Selected geotechnical and leaching properties were determined on 28-day old samples. These include unconfined compressive strength (UCS), bulk density, porosity, hydraulic conductivity, leachate pH and granular leachability of contaminants. Interrelationships among these properties were deduced using the most reasonable best fits determined by specialized curve fitting software. Strong quadratic and log-linear relationships exist between hydraulic conductivity and UCS, with increasing binder and water contents, respectively. However, the strength of interrelationships between hydraulic conductivity and porosity, UCS and porosity, and UCS and bulk density varies with binder and water contents. Leachate pH and granular leachability of contaminants are best related to UCS and hydraulic conductivity by a power law and an exponential function, respectively. These results suggest how the accuracy of not-easily-measurable performance properties may be constrained from simpler ones. Comparisons with some published performance properties data support this.

Improvement in engineering properties of soft-soil using cement and lime additives: A case study of southern Vietnam

Science.gov (United States)

To-Anh Phan, Vu; Ngoc-Anh Pham, Kha

2018-04-01

This paper presents the experimental results of using two additives to improve natural soft soil properties in southern Vietnam (i.g., cement and cement-lime mixture). The specimens were prepared by compacting method. Firstly, the natural soil was mixed with cement or cement-lime to determine the optimum water contents of various additive contents. Then, optimum water content was used to produce samples to test some engineering properties such as unconfined compressive strength, splitting tensile strength, and Young’s modulus. The specimens were tested by various curing duration of 7, 14, and 28 days. Results indicated that using cement additive is suitable for improvement of soft soil in the local area and cement-soil stabilization can be replaced as the subbase layer of the flexible pavement according to current Vietnamese standard. In addition, a higher cement content has a greater compressive strength as well as tensile strength. Besides, the Young’ modulus has significantly increased with a long-term curing age and more cement content. No evidences of increasing in strength and modulus are found with the cement-lime-soil stabilization. Finally, the best-fit power function is established by the relationships between unconfined compressive strength and splitting tensile strength as well unconfined compressive strength and Young’s Modulus, with the coefficient of determination, R2>0.999.

Effect of Palmyra Palm Leaf Ash on Cement Stabilization of Makurdi Shale

Directory of Open Access Journals (Sweden)

Amos Yala IORLIAM

2012-08-01

Full Text Available Makurdi Shale was treated with palmyra palm leaf ash (PPLA and cement to assess its suitability as a material in construction of flexible pavement. Classification, Compaction, Consistency, California bearing ratio (CBR and Unconfined compressive strength (UCS tests, were conducted on the shale specimen treated with, cement and PPLA in a combined incremental order of 2% up to 10% of cement and 2% up to 14% of PPLA of dry weight of soil sample respectively. Results of tests showed that Makurdi shale is an A-7-6, high plasticity (CH and high swell potential soil by the American Association of State Highway and Transportation Officials (AASHTO, Unified Soil Classification System (USCS and Nigerian Building and Road Research Institute (NBRRI classification systems respectively. The plasticity index (PI reduced from 30.5% for untreated Makurdi shale to 4% at 10% cement +14% PPLA contents. The maximum soaked CBR and 7 day UCS values of 92% and 1041 kN/m2 were obtained at 10% cement+14 % PPLA contents respectively. From the results, Makurdi shale treated with a combination of 10%cement+14% PPFA with a soaked CBR value of 92 %, 7 day UCS value of 1041 kN/m2 and 82 % value of resistance to loss in strength, satisfied the requirement for sub-base specification. It is therefore recommended for use as sub-base materials in flexible pavement.

Durabilidad de un suelo contaminado y tratado con cemento portland Durability of a contaminated soil treated with portland cement

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José W Jiménez Rojas

2008-01-01

Full Text Available Este trabajo tiene por objetivo la aplicación de la técnica de solidificación/estabilización de suelos contaminados, analizando específicamente el comportamiento físico del suelo a través de ensayos de durabilidad. El suelo fue contaminado en laboratorio con residuo oleoso y la aplicación de la técnica tuvo cómo agente de encapsulamiento el cemento Portland CP V-ARI. Los ensayos de durabilidad, realizados según la NBR 13554 (1996, tuvieron como objetivo estudiar el grado de desagregación y vulnerabilidad del material con diversas combinaciones de dosificaciones de cemento y residuo oleoso, así cómo estudiar la variación volumétrica de los mismos. A partir de los resultados es posible observar que cuanto mayor la cantidad de contaminante, mayor es la pérdida de masa. Sin embargo, cuánto mayor es la cantidad de cemento, menor es la pérdida de masa y menor la variación volumétrica.This work seeks the application of solidification/stabilization techniques to contaminated soils analyzing specifically de physical behavior of the soil through tests of durability. The soil was contaminated in laboratory with acidic oily sludge industrial residues and the application of that technique had an encapsulate agent, the Portland cement CP V-ARI. The tests were carried out according to NBR 13.554 (1996, and they aimed to study the level of degradation and the vulnerability of the material with several combinations of cement and acidic oily sludge as well as study their volumetric variations. Starting from the results, it is possible to observe that the larger the contamination the larger the mass loss; however the larger the amount of cement, the smaller the mass loss and the more stable the volumetric variation.

Soil stabilization 1982

Science.gov (United States)

Barenberg, E. J.; Thompson, M. R.; Tayabji, S. D.; Nussbaum, P. J.; Ciolko, A. T.

Seven papers cover the following areas: design, construction and performance of lime, fly ash, and slag pavement; evaluation of heavily loaded cement stabilized bases; coal refuse and fly ash compositions; potential highway base course materials; lime soil mixture design considerations for soils of southeastern United States; short term active soil property changes caused by injection of lime and fly ash; soil cement for use in stream channel grade stabilization structures; and reaction products of lime treated southeastern soils.

Effect of acid rain pH on leaching behavior of cement stabilized lead-contaminated soil.

Science.gov (United States)

Du, Yan-Jun; Wei, Ming-Li; Reddy, Krishna R; Liu, Zhao-Peng; Jin, Fei

2014-04-30

Cement stabilization is a practical approach to remediate soils contaminated with high levels of lead. However, the potential for leaching of lead out of these stabilized soils under variable acid rain pH conditions is a major environmental concern. This study investigates the effects of acid rain on the leaching characteristics of cement stabilized lead contaminated soil under different pH conditions. Clean kaolin clay and the same soil spiked with 2% lead contamination are stabilized with cement contents of 12 and 18% and then cured for 28 days. The soil samples are then subjected to a series of accelerated leaching tests (or semi-dynamic leaching tests) using a simulated acid rain leachant prepared at pH 2.0, 4.0 or 7.0. The results show that the strongly acidic leachant (pH ∼2.0) significantly altered the leaching behavior of lead as well as calcium present in the soil. However, the differences in the leaching behavior of the soil when the leachant was mildly acidic (pH ∼4.0) and neutral (pH ∼7.0) prove to be minor. In addition, it is observed that the lead contamination and cement content levels can have a considerable impact on the leaching behavior of the soils. Overall, the leachability of lead and calcium is attributed to the stability of the hydration products and their consequent influence on the soil buffering capacity and structure. Copyright © 2014 Elsevier B.V. All rights reserved.

Assessment of geotechnical properties of uncemented/cemented clayey soil incorporated with waste crumb rubber

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JITENDRA SINGH YADAV

2017-03-01

Full Text Available Discarded waste tires are becoming a serious threat to health, environment, and ecological systems worldwide if it is not disposed of properly. Every year 1000 million of waste tires are discarded. This number may grow up to 1200 million by the year 2030. On the other hand, construction of civil engineering structures such as buildings, dams, highways, etc. are at high risk of differential settlement, especially in the case of weak or soft clay, which is due to its low shear strength and high compressibility. The paper aims to assess geotechnical properties of uncemented/cemented clayey soil incorporated with waste crumb rubber. Compaction parameters, unconfined compressive strength, split tensile strength, toughness index, CBR values and swelling pressure of rubberized uncemented/cemented clayey soil (3%, and 6% cement and different percentage of crumb rubber have been obtained. After rigorous extensive study, it has been concluded that unconfined compressive strength and split tensile strength of rubberized cemented clayey soil decreases with the increase of the percentage of crumb rubber whereas the axial, and diametral strain are found to be increased with the addition of crumb rubber up to 5% after that it starts to decrease. The CBR values, swelling pressure, and toughness index of uncemented/cemented clayey soil was significantly affected by incorporation of crumb rubber. SEM studies have also been incorporated in this investigation.

Effect of drying-wetting cycles on leaching behavior of cement solidified lead-contaminated soil.

Science.gov (United States)

Li, Jiang-Shan; Xue, Qiang; Wang, Ping; Li, Zhen-Ze; Liu, Lei

2014-12-01

Lead contaminated soil was treated by different concentration of ordinary Portland cement (OPC). Solidified cylindrical samples were dried at 40°C in oven for 48 h subsequent to 24h of immersing in different solution for one drying-wetting. 10 cycles were conducted on specimens. The changes in mass loss of specimens, as well as leaching concentration and pH of filtered leachates were studied after each cycle. Results indicated that drying-wetting cycles could accelerate the leaching and deterioration of solidified specimens. The cumulative leached lead with acetic acid (pH=2.88) in this study was 109, 83 and 71 mg respectively for solidified specimens of cement-to-dry soil (C/Sd) ratios 0.2, 0.3 and 0.4, compared to 37, 30, and 25mg for a semi-dynamic leaching test. With the increase of cycle times, the cumulative mass loss of specimens increased linearly, but pH of filtered leachates decreased. The leachability and deterioration of solidified specimens increased with acidity of solution. Increases of C/Sd clearly reduced the leachability and deterioration behavior. Copyright © 2014 Elsevier Ltd. All rights reserved.

Pollution impact of cement production on air, soil and water in a ...

African Journals Online (AJOL)

Pollution impact of cement production on air, soil and water in a production location in Nigeria. ... Journal of Science and Technology (Ghana) ... location from the pollution source, which served as control for particulate and soil sampling.

Construction Technology and Mechanical Properties of a Cement-Soil Mixing Pile Reinforced by Basalt Fibre

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Yingwei Hong

2017-01-01

Full Text Available A new type of cement-soil mixing pile reinforced by basalt fibre is proposed for increasing the bearing capacity of cement-soil mixing piles. This work primarily consists of three parts. First, the process of construction technology is proposed, which could allow uniform mixing of the basalt fibre in cement-soil. Second, the optimal proportions of the compound mixtures and the mechanical properties of the pile material are obtained from unconfined compression strength test, tensile splitting strength test, and triaxial shear test under different conditions. Third, the reliability of the construction technology, optimal proportions, and mechanical properties are verified by testing the mechanical properties of the drilling core sample on site.

An assessment of post-remediation changes in sediment chemistry partitioning in an S/S treated soil.

Science.gov (United States)

Cutter, S.; MacLeod, C. L.; Canning, K.; Carey, P. J.; Hills, C. D.

2003-04-01

The Astra Pyrotechnics plant located in the Dartford Marshes, Kent, UK was the site of a field trial utilizing cement stabilization/solidification (S/S) in September 2000. A hotspot containing 35% copper and several thousand part per million lead and zinc was treated in order to trial an new form of cement stabilization (accelerated carbonation technology or ACT) developed by the Centre for Contaminated Land Remediation. A 10 by 20 meter plot was divided into 4 cells into which untreated, OPC (ordinary Portland cement) treated, Envirocem (a Lafarge special cement) treated and ACT treated soil was placed. Each cell has a leachate collection system and the leachate is monitored monthly. In August 2003, 24 cm cores were collected from each cell. These cores were analysed to determine changes in sediment chemistry and metal partitioning characteristics. Sediment chemistry was determined using an aqua regia digestion followed by ICP OES analysis. The CISMED extraction procedure was used to examine partitioning changes. The contaminant concentrations in the leachates remain below UK drinking water standards. However, seasonal cyclicity is observed with an increase of metals in the leachates during winter months. The sediment cores were analysed for Ca, Cr, Cu, Fe, K, Mn, Mg, Na, Ni, Pb and Zn. Only the untreated cell showed any discernable changes in metal concentration with depth. The S/S treated cells show no trends although differences in partitioning between the cells is observed.

Determination of Heavy Metal in Agricultural Soils near and Far From the Cement Factory in Tehran, Iran

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Mohammad Rezaeian

2016-08-01

Full Text Available Background: Heavy metals (HMs are one of the most important polluting substances emitted to the environment during cement production. Tehran Cement Factory located in the southeastern of Tehran, Iran, closer to agricultural lands cultivates alfalfa, barley, and maize as feed. The objective of the study was to determine the concentration of HMs in agricultural soils. Methods: Thirty six soil samples were collected from two regions of Aminabad (close to the cement factory and Varamin (far from cement factory in 2015. The samples were taken from a depth of 0-15 cm and analyzed to determine their HM (zinc, lead, cadmium and chromium by atomic absorption spectrophotometry. Other relevant parameters of soil were evaluated, such as; pH, EC, TOM. Results: The concentration of HMs in both regions was as follows: Pb> Zn > Cr > Cd. Generally, the soil alfalfa, barley and maize, there was no significant difference. Conclusion: These data provide information on HM accumulations in agricultural soils and allow us to identify sources of pollution. In the industrial area due to the proximity to cement factory, concentration of zinc, lead, chromium, pH and EC were more than non-contaminated areas.

Characterization of waste products prepared from radioactive contaminated clayey soil cemented according to the GEODUR process

International Nuclear Information System (INIS)

Brodersen, K.; Vinther, A.

1990-11-01

Radioactive contaminated soil may arise due to accidents of various types or may be detected during decommisioning of nuclear installations. Ordinary surface soil cannot normally be conditioned using conventional cementation processes since the content of humic materials retards or prevents the solidification. An additive available from the Danish firm Geodur A/S makes it possible to circumvent this difficulty and to produce a monolithic, nondusting waste type using rather small amounts of cement. The report describes work on characterization of such a cemented waste product prepared on basis of clayey top soil from the Risoe area. The claimed advantages of the process was verified, and data for the compression strength (low), hydraulic conductivity (satisfactory) and other pore structure-related properties are given for the obtained products. Unfortunately the behaviour of cesium and strontium, representing two of the most relevant radionuclides, was not too promising. The retention of cesium is satisfactory, but less good than for the untreated soil. Greatly improved cesium retention after drying of the materials was noticed. Good retention of strontium is only obtained after reaction of the material with carbon dioxide from the atmosphere. The behaviour of the two isotopes in other types of cemented waste is somewhat similar, but the decrease in retention compared with untreated soil makes the process less interesting as a possibility for remedial actions after accidents, etc. Some further studies of the cemented soil waste are beeing made within the frame of the Nordic Nuclear Safety Studies. Elements forming low solublity components in the high pH environment in the cemented soil will probably be retained quite efficiently. This was demonstrated in case of Zn. (author) 11 tabs., 22 ills., 8 refs

The effect of endoskeleton on antibiotic impregnated cement spacer for treating deep hip infection

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Hsu Wei-Hsiu

2011-01-01

Full Text Available Abstract Backgrounds A two-stage revision arthroplasty was suggested optimal treatment for deep infections in hip joint. The effect of endoskeleton of cement spacers on the interim function and infection control remains unclear. Methods From Jan. 2004 to Dec. 2007, we collected a prospective cohort of consecutive 34 patients who treated with two-stage revision total hip arthroplasty for deep infection of hip joint. In group 1, fifteen patients were treated by a novel design augmented with hip compression screw while nineteen patients were treated by traditional design in group 2. Results No fracture of cement spacer occurred in group 1 while 6 cases developed spacer failure in group 2. (p Conclusions Patients being treated for deep infection of hip joint using cement spacer augmented with stronger endoskeleton have lower pain levels and better joint function between stages.

Assessment of Physical and Mechanical Properties of Cement Panel Influenced by Treated and Untreated Coconut Fiber Addition

Science.gov (United States)

Abdullah, Alida; Jamaludin, Shamsul Baharin; Anwar, Mohamed Iylia; Noor, Mazlee Mohd; Hussin, Kamarudin

This project was conducted to produce a cement panel with the addition of treated and untreated coconut fiber in cement panel. Coconut fiber was added to replace coarse aggregate (sand) in this cement panel. In this project, the ratios used to design the mixture were 1:1:0, 1:0.97:0.03, 1:0.94:0.06, 1:0.91:0.09 (cement: sand: coconut fiber). The water cement ratio was constant at 0.55. The sizes of sample tested were, 160 mm x 40 mm x 40 mm for compression test, and 100 mm x 100 mm x 40 mm for density, moisture content and water absorption tests. After curing samples for 28 days, it was found that the addition of coconut fiber, further increase in compressive strength of cement panel with untreated coconut fiber. Moisture content of cement panel with treated coconut fiber increased with increasing content of coconut fiber whereas water absorption of cement panel with untreated coconut fiber increased with increasing content of coconut fiber. The density of cement panel decreased with the addition of untreated and treated coconut fiber.

EXPERIMENTAL STUDY OF SOIL CEMENT BRICKS AND CHARACTERISTICS COMPRESSIVESTRENGTH OF BRICK MASONRY WALL

OpenAIRE

S. Divya; K. Nithya; S. Manoj Kumar; K. Saravanakumar

2017-01-01

This research is intended to provide detailed technical and economic information on the production of compressed cement stabilised soil bricks. These include information on suitable soil types, local stabilisers, stabilization techniques, production of compressed stabilized soil bricks and their economical value and potential. Critical review of related literatures show that soil types, proportions between soil and stabilizer and compaction pressure applied to the moist soil mix affects the q...

Lithological and land-use based assessment of heavy metal pollution in soils surrounding a cement plant in SW Europe.

Science.gov (United States)

Cutillas-Barreiro, Laura; Pérez-Rodríguez, Paula; Gómez-Armesto, Antía; Fernández-Sanjurjo, María José; Álvarez-Rodríguez, Esperanza; Núñez-Delgado, Avelino; Arias-Estévez, Manuel; Nóvoa-Muñoz, Juan Carlos

2016-08-15

We study the influence of phasing out a cement plant on the heavy metal (Hg, Pb and Cr) content in the surrounding soils, taking into account factors often neglected, such as contributions due to local lithology or land use. The range of total Hg was 10-144µg kg(-1), reaching up to 41 and 145mgkg(-1) for total contents of Pb and Cr, respectively. Forest soils showed higher concentration of Hg than prairie soils, indicating the importance of land use on the accumulation of volatile heavy metals in soils. In forest soils, total Hg showed a trend to decrease with soil depth, whereas in prairie soils the vertical pattern of heavy metal concentrations was quite homogeneous. In most cases, the distance to the cement plant was not a factor of influence in the soils content of the analyzed heavy metals. Total Pb and Cr contents in soils nearby the cement plant were quite similar to those found in the local lithology, resulting in enrichment factor values (EF's) below 2. This suggests that soil parent material is the main source of these heavy metals in the studied soils, while the contribution of the cement plant to Pb and Cr soil pollution was almost negligible. On the contrary, the soils surrounding the cement plant accumulate a significant amount of Hg, compared to the underlying lithology. This was especially noticeable in forest soils, where Hg EF achieved values up to 36. These results are of relevance, bearing in mind that Hg accumulation in soils may be an issue of environmental concern, particularly in prairie soils, where temporal flooding can favor Hg transformation to highly toxic methyl-Hg. In addition, the concurrence of acid soils and total-Cr concentrations in the range of those considered phytotoxic should be also stressed. Copyright © 2016 Elsevier B.V. All rights reserved.

COMPARATIVE ASSESSMENT OF RICE HUSK ASH, POWDERED GLASS AND CEMENT AS LATERITIC SOIL STABILIZERS

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Adebisi Ridwan

2016-10-01

Full Text Available This paper compares the stabilizing effects of three different materials, namely: rice husk ash, powdered glass, and cement on the properties of lateritic soil. The basic properties of the lateritic soil were first obtained through colour, moisture content determination, specific gravity, particle size distribution and Atterberg limits tests. Each of the stabilizing materials was then mixed with the lateritic soil in varying percentages of 2.5%, 5%, 7.5%, 10%, 12.5% and 15% by weight of the soil. Thereafter, compaction and California bearing ratio (CBR tests were carried out on the sample mixes to determine the effects of the materials on the lateritic soil. Chemical tests were also carried out on the samples to determine their percentage oxides composition. The compaction test showed that the highest maximum dry densities (MDD obtained for the mixed samples were 2.32 g/cm3 (at 2.5% cement addition, 2.28g/cm3 (at 5% powdered glass (PG addition and 2.18 g/cm3 (at 5% rice husk ash (RHA addition with corresponding optimum moisture contents (OMC of 10.06%, 14.3% and 12.31% respectively. The CBR tests showed that the CBR values increased in all cases as the materials were added with those of the cement and powdered glass giving the highest values and showing close semblance under unsoaked conditions. The chemical test showed that the significant oxides present in the cement, powdered glass and rice husk ash were CaO (53.60%, SiO2 (68.45% and SiO2 (89.84% respectively.

Equilibrium leaching of toxic elements from cement stabilized soil.

Science.gov (United States)

Voglar, Grega E; Leštan, Domen

2013-02-15

The toxicity characteristics leaching procedure (TCLP) is commonly used to assess the efficiency of solidification/stabilization (S/S) of pollutants in wastes, despite recent objections to this method. In this study, formulations of 7, 10, 15 and 20% (w/w) of calcium aluminate cement (CAC) and sulfate resistant Portland cement (SRC) were used for S/S of soil from brownfield contaminated with 43,149, 10,115, 7631, 6130, 90, 82 mg kg(-1) of Zn, Pb, Cu, As, Cd and Ni, respectively. CAC produced S/S soil monoliths of higher mechanical strength (up to 7.65 N mm(-2)). Mass-transfer analysis indicated surface wash-off as a mechanism of toxic elements release, and equilibrium leaching as a crucial parameter of S/S efficiency assessment. In the expected range of field soil pH after S/S (pH 7-9), the TCLP gave markedly different results than the multi-point pH equilibrium leaching method (using nine targeted pH values): up to 2953-, 94-, 483-, 1.3-, 27- and 1.5-times more Zn, Pb, Cu, As, Cd and Ni, respectively, was determined in the TCLP leachate. S/S with CAC reduced leachability of toxic elements more effectively than SRC. Our results indicate that, under given field conditions, the TCLP significantly underrates the efficiency of S/S of contaminated soil with cementitious binders. Copyright © 2012 Elsevier B.V. All rights reserved.

The role of curing period on the engineering characteristics of a cement-stabilized soil

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Athanasopoulou Antonia

2016-07-01

Full Text Available Very often, pavements constructed in an economical manner or matching surface elevations of adjacent lanes cannot be designed for the soil conditions of the existing subgrade. Therefore, there is a need to stabilize the soil with an appropriate chemical substance in order to increase its strength to a satisfactory level. For the enhancement of subgrade soil strength characteristics, lime and cement are the most commonly used stabilizers. An experimental program was directed to the evaluation of a clayey soil and its mixtures with different cement contents performing tests on the index properties, the moisture-density relation, the unconfined compressive strength, and linear shrinkage. There is a definite improvement in strength. The time interval used to cure the prepared specimens affected positively both strength and plasticity features of the mixtures. A comparison with mixtures of the same soil with lime has been made, because of the wide use of lime in clay soil stabilization projects.

Cement treated recycled crushed concrete and masonry aggregates for pavements

NARCIS (Netherlands)

Xuan, D.X.

2012-01-01

This research is focusing on the characterization of the mechanical and deformation properties of cement treated mixtures made of recycled concrete and masonry aggregates (CTMiGr) in relation to their mixture variables. An extensive laboratory investigation was carried out, in which the mechanical

STRESS-STRAIN STATE OF ROCKFILL DAM DOUBLE-LAYER FACE MADE OF REINFORCED CONCRETE AND SOIL-CEMENT CONCRETE

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Sainov Mikhail Petrovich

2017-05-01

Full Text Available There was studied the stress-strain state of 215 m high rockfill dam where the seepage-control element is presented by a reinforced concrete face of soil-cement concrete placed on the under-face zone. Calculations were carried out for two possible variants of deformability of rock outline taking into account the non-linearity of its deformative properties. It was obtained that the reinforced concrete face and the soil-cement concrete under-face zone work jointly as a single construction - a double-layer face. As the face assembly resting on rock is made with a sliding joint the scheme of its static operation is similar to the that of the beam operation on the elastic foundation. At that, the upstream surface of the double-layer face is in the compressed zone and lower one is in the tensile zone. This protects the face against cracking on the upstream surface but threatens with structural failure of soil-cement concrete. In order to avoid appearance of cracks in soil-cement concrete part due to tension it is necessary to achieve proper compaction of rockfill and arrange transverse joints in the double-layer face.

Runoff on Pavements of Soil-Cement Blocks – an Experimental Boarding

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Zegarra-Tarqui Jorge Luis

2015-01-01

Full Text Available The article evaluates the reduction of runoff in pavements constructed with rectangular blocks of soil-cement. The tests were conducted in a pilot pavement built with soil-cement blocks, seated in a metal box of 50 cm × 50 cm (area = 2500 cm2, with declivities of 1%, 3% and 5%. Mean intensities of 76.9 mm / I 117.7 mm / h were used, values close to the intensities calculated by intensity-frequency-duration (i-f- -d equation of the city of Salvador, Brazil, for return periods of 2 and 5 years, respectively. The medium runoff coefficient was C = 0.61, this value is close to the coefficient of pavement with rectangular blocks (C = 0.6 and it has a lower value than the coefficient for concrete block pavement (C = 0.78. On the other hand, considering that areas with more than 2500 cm2 are constituted by coupling of area units of 50 cm × 50 cm, the splash losses are part of the runoff, obtaining the coefficient Csuperficial + splashing, which showed values in the 0.74 to 0.89 range, these values were found close to the coefficient of concrete block pavement (C = 0.78 and below the concrete pavement (C = 0.95, respectively, but factors such as displacement time of runoff on surface, depressions on the surface, roughness of pavement, evaporation and others, should reduce this value. Then, the pavement of soil-cement blocks can be considered in the category of semi-permeable for the area size used.

Field and lab evaluation of the use of lime fly ash to replace soil cement as a base course : final report.

Science.gov (United States)

1997-09-01

This study evaluates the performance of lime/fly ash stabilized base as an alternative to soil cement stabilized base for flexible pavement systems on reconstructed highways in Louisiana. Louisiana has historically used soil cement for most flexible ...

Thermal-treated soil for mercury removal: Soil and phytotoxicity tests

Energy Technology Data Exchange (ETDEWEB)

Roh, Y.; Edwards, N.T.; Lee, S.Y.; Stiles, C.A.; Armes, S.; Foss, J.E.

2000-04-01

Mercury (Hg) contamination of soils and sediments is one of many environmental problems at the Oak Ridge Reservation, Oak Ridge, TN. Mercury-contaminated soil from the Lower East Fork Poplar Creek (LEFPC) at the Oak Ridge Reservation was treated thermally to reduce Hg concentration to a below target level (20 mg kg{sup {minus}1}) as a pilot scale thermal treatment demonstration. As a part of performance evaluation, the soil characteristics and plant growth response of the untreated and treated soil were examined. The soil treated at 350 C retained most of its original soil properties, but the soil treated at 600 C exhibited considerable changes in mineralogical composition and physicochemical characteristics. Growth and physiological response of the three plant species radish (Raphanus sativus L.), fescue (Festuca arundinacea Schreb.), and oat (Avena sativa L.) indicated adverse effects of the thermal treatment. The addition of N fertilizer had beneficial effects in the 350 C treated soil, but had little beneficial effect in the 600 C treated soil. Some changes of soil characteristics induced by thermal treatment cannot be avoided. Soil characteristics and phytotoxicity test results strongly suggest that changes occurring following the 350 C treatment do not limit the use of the treated soil to refill the excavated site for full-scale remediation. The only problem with the 350 C treatment is that small amounts of Hg compounds (<15 mg kg{sup {minus}1}) remain in the soil and a processing cost of $45/Mg.

The Effect of Polymer-Cement Stabilization on the Unconfined Compressive Strength of Liquefiable Soils

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Ali Ateş

2013-01-01

Full Text Available Soil stabilization has been widely used as an alternative to substitute the lack of suitable material on site. The use of nontraditional chemical stabilizers in soil improvement is growing daily. In this study a laboratory experiment was conducted to evaluate the effects of waterborne polymer on unconfined compression strength and to study the effect of cement grout on pre-venting of liquefiable sandy soils. The laboratory tests were performed including grain size of sandy soil, unit weight, ultrasonic pulse velocity, and unconfined compressive strength test. The sand and various amounts of polymer (1%, 2%, 3%, and 4% and cement (10%, 20%, 30%, and 40% were mixed with all of them into dough using mechanical kneader in laboratory conditions. Grouting experiment is performed with a cylindrical mould of  mm. The samples were subjected to unconfined compression tests to determine their strength after 7 and 14 days of curing. The results of the tests indicated that the waterborne polymer significantly improved the unconfined compression strength of sandy soils which have susceptibility of liquefaction.

Geochemical analysis of leachates from cement/low-level radioactive waste/soil systems

International Nuclear Information System (INIS)

Criscenti, L.J.; Serne, R.J.

1988-09-01

Laboratory experiments were conducted as part of the Special Waste Form Lysimeters/endash/Arid Program. These experiments were conducted to investigate the performance of solidified low-level nuclear waste in a typical arid, near-surface disposal site, and to evaluate the ability of laboratory tests to predict leaching in actual field conditions. Batch leaching, soil adsorption column, and soil/waste form column experiments were conducted using Portland III cement waste forms containing boiling-water reactor evaporator concentrate and ion-exchange resin waste. In order to understand the reaction chemistry of the cement waste form/soil/ground-water system, the compositions of the leachates from the laboratory experiments were studied with the aid of the MINTEQ ion speciation/solubility and mass transfer computer code. The purpose of this report is to describe the changes in leachate composition that occur during the course of the experiments, to discuss the geochemical modeling results, and to explore the factors controlling the major element chemistry of these leachates. 18 refs., 84 figs., 14 tabs

Development of soil-cement blocks with three interventions: natural soil, soil corrected with sand and soil more phase change materials (PCMs); Desenvolvimento de blocos solo-cimento com tres intervencoes: solo natural, solo corrigido com areia e solo mais materiais de mudanca de fase (MMFs)

Energy Technology Data Exchange (ETDEWEB)

Dantas, Valter Bezerra; Gomes, Uilame Umbelino; Reis, Edmilson Pedreira; Valcacer, Samara Melo; Silva, A.S., E-mail: valter.fisic@hotmail.com, E-mail: umbelino@dfte.ufrn.br, E-mail: pedreira.reis@ig.com.br, E-mail: gmarinho@ct.ufrn.br, E-mail: samaravalcacer@hotamil.com, E-mail: ariadness2@yahoo.com.br [Universidade Federal do Rio Grande do Norte (PPGCEM/UFRN), Natal, RN (Brazil). Departamento de Fisica Teorica e Experimental. Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

2014-07-01

In this work, the results of characterization tests of soil samples collected in Mossoro-RN, UFERSA-RN Campus, located approximately 20 meters high, and {sup 5} ° 12'34.68 south latitude and 37 ° 19'5.74 {sup w}est longitude, with the purpose of producing soil-cement for the manufacture of pressed blocks with good resistance to compression and thermal stability. The following tests were performed: granulometry, plasticity limit, liquidity limit, particle size correction, scanning electron microscopy (SEM), X-ray fluorescence. In this soil, based on the results of the granulometric analysis, 10% of medium sand with 3% and 5% of eicosane paraffin and 10% of medium sand with 3% and 5% of paraffin 120 / 125F were added, forming analysis compositions, standard soil-cement block and natural soil-cement block with addition of 10% medium sand and 0% paraffin. Paraffins are referred to as PCMs (Phase Change Material). The contrasting effect between the different dosages on the compressive strength values of the soil-cement blocks was observed. The objective is to create new materials that give the block quality equal to or higher than the recommendations of ABNT norms, and that offer greater thermal comfort in the constructions. Soil particles of different sizes were added to 8% (by weight) of cement, and about 9.20% of water added to the mixture.

The Estimation of Compaction Parameter Values Based on Soil Properties Values Stabilized with Portland Cement

Science.gov (United States)

Lubis, A. S.; Muis, Z. A.; Pasaribu, M. I.

2017-03-01

The strength and durability of pavement construction is highly dependent on the properties and subgrade bearing capacity. This then led to the idea of the selection methods to estimate the density of the soil with the proper implementation of the system, fast and economical. This study aims to estimate the compaction parameter value namely the maximum dry unit weight (γd max) and optimum moisture content (wopt) of the soil properties value that stabilized with Portland Cement. Tests conducted in the laboratory of soil mechanics to determine the index properties (fines and liquid limit) and Standard Compaction Test. Soil samples that have Plasticity Index (PI) between 0-15% then mixed with Portland Cement (PC) with variations of 2%, 4%, 6%, 8% and 10%, each 10 samples. The results showed that the maximum dry unit weight (γd max) and wopt has a significant relationship with percent fines, liquid limit and the percentation of cement. Equation for the estimated maximum dry unit weight (γd max) = 1.782 - 0.011*LL + 0,000*F + 0.006*PS with R2 = 0.915 and the estimated optimum moisture content (wopt) = 3.441 + 0.594*LL + 0,025*F + 0,024*PS with R2 = 0.726.

An evaluation of the composition of soil cement bricks with construction and demolition waste - doi: 10.4025/actascitechnol.v33i2.9377

Directory of Open Access Journals (Sweden)

Antonio Anderson da Silva Segantini

2011-04-01

Full Text Available Sustainable development requires the existence of a production network that includes the reuse of construction waste for new materials. Current analysis investigates an optimal soil-cement composition made up of construction and demolition waste for the manufacture of pressed bricks. Soil-cement bricks were manufactured from construction and demolition wastes (CDW, A-4 classified fine sandy soil and cement CP II Z 32. Laboratory tests, comprising test compaction, optimum water content and maximum dry specific weight, consistency limits, grain size distribution and linear shrinkage, were made to characterize the materials researched. Compressive strength and absorption tests were also undertaken in different combinations of composition. Results showed that the application of CDW improved soil-cement qualities and reduced shrinkage of the material used.

Durability of compressed soil-cement bricks

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Acosta Valle, A.

2001-06-01

Full Text Available This papers shows the evaluation process of the durability of compressed soil-cement bricks. A great number of tests were made to determine the behavior of bricks when they are compression loaded and under the influence of moisture. Two different types of soils were used to produce the bricks, a lime-clay soil and a sand one. The sand soil is very resistant. The other one has a limited use. An experimental design was used to test the bricks. It is a rotational and quadratic method with a hexagonal figure which contains replicas at the central point. This method ensures the reliability of test results. Otherwise, it would reduce the amount of specimens necessary for the tests. The optimun moisture content is obtained by using a press machine. It is more rational than the standard Proctor compactation test, because it applies the same type and amount of energy used to produce the bricks. The obtained results show the behavior differences between the two compressed soil-cement bricks subjected to the compression test, water absorption and wetting and drying tests. The durability tests results are very important in the possible use of the bricks produced.

En el trabajo se evalúa la durabilidad de elementos aglomerados de suelo estabilizado. Se realiza un amplio número de ensayos encaminados a determinar el comportamiento frente a la acción de las cargas y la humedad de dos suelos con características diferentes: uno limo-arcilloso y el otro arenoso. Este último presenta resultados muy favorables en ambas direcciones. El otro, con un posible uso más limitado. Se emplea un método de diseño experimental del tipo rotacional cuadrático en hexágono, con réplicas en el punto central, el que garantiza la confiabilidad de los resultados de los ensayos, a la vez que disminuye la cantidad de especímenes a ensayar. Se determina la humedad óptima a utilizar en las diferentes dosificaciones empleando la máquina compactadora, que resulta m

Efficiency modeling of solidification/stabilization of multi-metal contaminated industrial soil using cement and additives.

Science.gov (United States)

Voglar, Grega E; Leštan, Domen

2011-08-30

In a laboratory study, formulations of 15% (w/w) of ordinary Portland cement (OPC), calcium aluminate cement (CAC) and pozzolanic cement (PC) and additives: plasticizers cementol delta ekstra (PCDE) and cementol antikorodin (PCA), polypropylene fibers (PPF), polyoxyethylene-sorbitan monooleate (Tween 80) and aqueous acrylic polymer dispersion (Akrimal) were used for solidification/stabilization (S/S) of soils from an industrial brownfield contaminated with up to 157, 32,175, 44,074, 7614, 253 and 7085mg kg(-1) of Cd, Pb, Zn, Cu, Ni and As, respectively. Soils formed solid monoliths with all cementitious formulations tested, with a maximum mechanical strength of 12N mm(-2) achieved after S/S with CAC+PCA. To assess the S/S efficiency of the used formulations for multi-element contaminated soils, we propose an empirical model in which data on equilibrium leaching of toxic elements into deionized water and TCLP (toxicity characteristic leaching procedure) solution and the mass transfer of elements from soil monoliths were weighed against the relative potential hazard of the particular toxic element. Based on the model calculation, the most efficient S/S formulation was CAC+Akrimal, which reduced soil leachability of Cd, Pb, Zn, Cu, Ni and As into deionized water below the limit of quantification and into TCLP solution by up to 55, 185, 8750, 214, 4.7 and 1.2-times, respectively; and the mass transfer of elements from soil monoliths by up to 740, 746, 104,000, 4.7, 343 and 181-times, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

Efficiency modeling of solidification/stabilization of multi-metal contaminated industrial soil using cement and additives

International Nuclear Information System (INIS)

Voglar, Grega E.; Lestan, Domen

2011-01-01

Highlights: → We assess the feasibility of using soil S/S for industrial land reclamation. → Retarders, accelerators, plasticizers were used in S/S cementitious formulation. → We proposed novel S/S efficiency model for multi-metal contaminated soils. - Abstract: In a laboratory study, formulations of 15% (w/w) of ordinary Portland cement (OPC), calcium aluminate cement (CAC) and pozzolanic cement (PC) and additives: plasticizers cementol delta ekstra (PCDE) and cementol antikorodin (PCA), polypropylene fibers (PPF), polyoxyethylene-sorbitan monooleate (Tween 80) and aqueous acrylic polymer dispersion (Akrimal) were used for solidification/stabilization (S/S) of soils from an industrial brownfield contaminated with up to 157, 32,175, 44,074, 7614, 253 and 7085 mg kg -1 of Cd, Pb, Zn, Cu, Ni and As, respectively. Soils formed solid monoliths with all cementitious formulations tested, with a maximum mechanical strength of 12 N mm -2 achieved after S/S with CAC + PCA. To assess the S/S efficiency of the used formulations for multi-element contaminated soils, we propose an empirical model in which data on equilibrium leaching of toxic elements into deionized water and TCLP (toxicity characteristic leaching procedure) solution and the mass transfer of elements from soil monoliths were weighed against the relative potential hazard of the particular toxic element. Based on the model calculation, the most efficient S/S formulation was CAC + Akrimal, which reduced soil leachability of Cd, Pb, Zn, Cu, Ni and As into deionized water below the limit of quantification and into TCLP solution by up to 55, 185, 8750, 214, 4.7 and 1.2-times, respectively; and the mass transfer of elements from soil monoliths by up to 740, 746, 104,000, 4.7, 343 and 181-times, respectively.

Efficiency modeling of solidification/stabilization of multi-metal contaminated industrial soil using cement and additives

Energy Technology Data Exchange (ETDEWEB)

Voglar, Grega E. [RDA - Regional Development Agency Celje, Kidriceva ulica 25, 3000 Celje (Slovenia); Lestan, Domen, E-mail: domen.lestan@bf.uni-lj.si [Agronomy Department, Centre for Soil and Environmental Science, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana (Slovenia)

2011-08-30

Highlights: {yields} We assess the feasibility of using soil S/S for industrial land reclamation. {yields} Retarders, accelerators, plasticizers were used in S/S cementitious formulation. {yields} We proposed novel S/S efficiency model for multi-metal contaminated soils. - Abstract: In a laboratory study, formulations of 15% (w/w) of ordinary Portland cement (OPC), calcium aluminate cement (CAC) and pozzolanic cement (PC) and additives: plasticizers cementol delta ekstra (PCDE) and cementol antikorodin (PCA), polypropylene fibers (PPF), polyoxyethylene-sorbitan monooleate (Tween 80) and aqueous acrylic polymer dispersion (Akrimal) were used for solidification/stabilization (S/S) of soils from an industrial brownfield contaminated with up to 157, 32,175, 44,074, 7614, 253 and 7085 mg kg{sup -1} of Cd, Pb, Zn, Cu, Ni and As, respectively. Soils formed solid monoliths with all cementitious formulations tested, with a maximum mechanical strength of 12 N mm{sup -2} achieved after S/S with CAC + PCA. To assess the S/S efficiency of the used formulations for multi-element contaminated soils, we propose an empirical model in which data on equilibrium leaching of toxic elements into deionized water and TCLP (toxicity characteristic leaching procedure) solution and the mass transfer of elements from soil monoliths were weighed against the relative potential hazard of the particular toxic element. Based on the model calculation, the most efficient S/S formulation was CAC + Akrimal, which reduced soil leachability of Cd, Pb, Zn, Cu, Ni and As into deionized water below the limit of quantification and into TCLP solution by up to 55, 185, 8750, 214, 4.7 and 1.2-times, respectively; and the mass transfer of elements from soil monoliths by up to 740, 746, 104,000, 4.7, 343 and 181-times, respectively.

Quality evaluation of soil-cement-plant residue bricks by the combination of destructive and non-destructive tests

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Regis de C. Ferreira

Full Text Available ABSTRACT Residues from agricultural activity can be used to improve the quality of soil-based bricks, constituting an interesting alternative for their destination. The technical quality of soil-cement-plant residue bricks was evaluated by the combination of non-destructive and destructive methods. A predominant clayey soil, Portland cement and residues of husks of both rice and Brachiaria brizantha cv. Marandu (0, 10, 20, 30 and 40%, in mass, in substitution to the 10% cement content were used. The bricks were submitted to destructive (water absorption and compressive strength and nondestructive (ultrasound tests for their physical and mechanical characterization. Results from both destructive and non-destructive tests were combined to determine the quantitative parameter named “anisotropic resistance” in order to evaluate the quality of the bricks. The addition that promoted best technical quality was 10% residue content, regardless of the residue type. The anisotropic resistance proved to be adequate for the technical quality evaluation of the bricks.

Leachability of Arsenic (As) Contaminated Landfill Soil Stabilised by Cement and Bagasse Ash

Science.gov (United States)

Azhar, A. T. S.; Azim, M. A. M.; Aziman, M.; Nabila, A. T. A.

2016-11-01

Contaminated soil with heavy metals, especially Arsenic (As) has become a major issue worldwide. As is reported to be a metal that affects human health and is related to have caused serious diseases that interrupts the nervous system, blood vessels and kidneys. However, proper treatment techniques such as Stabilization/Solidification (S/S) method can be employed and is capable of controlling these heavy metals from contaminating the soil strata and groundwater resources. This study is to investigate the leachability of Arsenic (As) in S/S method when bagasse ash (BA) is added to remedy contaminated Landfill soil. Cement is added at a proportion of 5%, 10%, 15% and 20% in sample weights without BA while in another sample; the cement replaces BA at a proportion of 2.5%, 5%, 7.5%. and 10%. All samples were allowed to harden and cured at room temperature for 7, 14 and 28 days. The effectiveness of the treatment was assessed by conducting Synthetic Precipitation Leaching Procedure (SPLP). Results indicate that pH and leachability are found to have major influence on metal release. The final pH after leaching tests showed improvements especially samples containing BA. In addition, the concentration of As in the SPLP test after the curing period of 28 days were detected to be below the leachability limit as regulated by WHO's Guidelines for Drinking-water Quality. As a whole, the results obtained from testing showed that sample containing 10% cement with 10% BA is the most effective and is the optimum mix since this proportion succeeded in minimising the leachability of As at total reduction by 100%, In conclusion, partial replacement of cement with BA in the binder system has been successful in reducing the leachability.

STUDY OF THE EFFECT OF SOIL CEMENT ELEMENTS WHEN STABILIZING ROADBED MODEL IN LABORATORY CONDITIONS

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V. D Petrenko

2017-12-01

Full Text Available Purpose.Experimental studies allow determining th estress-strain state or bearing capacity of the tested soil body. A preliminary study of the results of model testing and experimental research allows us to find the optimal solutions and to justify the parameters of the chosen technology. The purpose of this work is to determine the effect of soil cement elements when stabilizing the roadbed on a weak subgrade using the soil tests in laboratory conditions. Methodology. During the development of measures for the reconstruction and consolidation of soil bodies, their strength is tested using many methods. In all cases, we take into account the physical and mechanical characteristics of soils obtained as a result of research, as well as the existing regulatory documents. We performed the experimental studies by model testing in laboratory conditions. The model testing was based on the corresponding relationships between geometric sizes, mechanical properties of materials, loads and other factors on which the stress-strain state depends. During testing, the model was loaded gradually. We maintained each load level up to conditional stabilization of the soil deformation. We took the readings from measuring devices at each stage of loading after achievement of stabilization of soil mass deformations. We fixed the readings in the test journal. Findings. During stabilization with soil cement piles there is an improvement in mechanical properties, which leads to a decrease in deformations by 2…3.5 times. Each test is accompanied with graphs of relative deformations-stress dependence, as well as deformation curves and compression curves. According to the results of experimental stu-dies, it can be seen that when testing a model with cement piles, compared with a model without soil cement piles, the relative deformations of the samples taken prior to the experiment and after the experiment almost coincide, indicating a decrease in deformability under

Effect of geotextile and cement on the performance of sabkha subgrade

Energy Technology Data Exchange (ETDEWEB)

Aiban, S.A.; Al-Ahmadi, H.M.; Siddique, Z.U.; Al-Amoudi, O.S.B. [Department of Civil Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Asi, I.M. [Department of Civil Engineering, Hashemite University, Zarqa 13115 (Jordan)

2006-06-15

Many construction and post-construction problems have been reported in the literature when sabkha soils have been used without an understanding of their abnormal behavior, especially their inferior loading capability in their natural conditions. The strength of these soils can be further significantly decreased if the sabkha is soaked. The main objective of this study was to upgrade the load-carrying capacity of pavements constructed on sabkha soils using geotextiles, and to assess the effect of geotextile grade, base thickness, loading type (static and dynamic) and moisture condition (as-molded and soaked) on the performance of soil-fabric-aggregate (SFA) systems. In addition, the sabkha soil was treated with different dosages (5%, 7%, and 10%) of Portland cement and the performance of cement-stabilized sabkha was compared to that of the SFA system under different testing conditions. The ANOVA results indicated that the use of geotextile has a beneficial effect on sabkha soils, especially under wet conditions. Although the improvement in the load-carrying capacity of sabkha samples with high dosages of cement showed better results than the inclusion of geotextile, an economic analysis showed that the use of geotextiles would be superior. Moreover, mechanistic analysis was used to develop a prediction model for the percentage increase in the modulus of resilience. (author)

Stabilization of Ikpayongo laterite with cement and calcium carbide ...

African Journals Online (AJOL)

Laterite obtained from Ikpayongo was stabilized with 2-10 % cement and 2-10 % Calcium Carbide waste, for use as pavement material. Atterberg's limits test, California bearing ratio (CBR) and unconfined compressive strength (UCS) tests were conducted on the natural laterite and the treated soil specimens. The plasticity ...

Strength, shrinkage, erodibility and capillary flow characteristics of cement-treated recycled pavement materials

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William Fedrigo

2017-09-01

Full Text Available Full-depth recycling with portland cement (FDR-PC has been widely used for pavement rehabilitation; however, doubts remain regarding factors affecting some properties of the recycled material. Aiming on quantifying the effects of those factors on the strength, drying shrinkage, erodibility, capillary rise and absorption of cement-treated mixtures (CTM of reclaimed asphalt pavement (RAP and graded crushed stone, tests were conducted considering different RAP contents, cement contents, compaction efforts and curing times. Cement addition increased the mixtures strength and reduced their erodibility and capillary flow characteristics, but increased shrinkage. Low cement contents resulted in acceptable strength for CTM, but in high capillary rise and absorption, not being suitable if the layer is exposed to long periods of water soaking. Higher compaction effort led to similar effects as cement addition, counterbalancing low cement contents usage and reducing costs and shrinkage cracking risk. Strength and shrinkage showed higher growth rates at early stages, and then precautions should be taken in order to avoid moisture loss. Increasing RAP content decreased strength; though, RAP effect on the other properties was statistically non-significant, indicating a similar behaviour as CTM without RAP. Considering the studied properties, the mixture with most satisfactory behaviour for field applications was identified. The results highlighted strength is not the only property to be considered when designing FDR-PC mixtures; although presenting acceptable strength, some mixtures may fail due to shrinkage cracking or erosion, when exposed to water content variations. Keywords: Full-depth recycling with cement, Strength, Drying shrinkage, Erodibility, Capillary rise, Absorption

Hybrid life cycle assessment comparison of colloidal silica and cement grouted soil barrier remediation technologies.

Science.gov (United States)

Gallagher, Patricia M; Spatari, Sabrina; Cucura, Jeffrey

2013-04-15

Site remediation involves balancing numerous costs and benefits but often neglects the environmental impacts over the entire project life cycle. Life cycle assessment (LCA) offers a framework for inclusion of global environmental "systems-level" decision metrics in combination with technological and cost analysis. We compare colloidal silica (CS) and cement grouted soil barrier remediation technologies for soils affected by low level radionuclides at a U.S. Superfund site using hybrid LCA methods. CS is a new, high performance grouting material installed using permeation grouting techniques. Cement, a more traditional grouting material, is typically installed using jet grouting techniques. Life cycle impacts were evaluated using the US EPA TRACI 2 model. Results show the highest life cycle environmental impacts for the CS barrier occur during materials production and transportation to the site. In general, the life cycle impacts for the cement barrier were dominated by materials production; however, in the extreme scenario the life cycle impacts were dominated by truck transportation of spoils to a distant, off-site radioactive waste facility. It is only in the extreme scenario tested in which soils are transported by truck (Option 2) that spoils waste transport dominates LCIA results. Life cycle environmental impacts for both grout barriers were most sensitive to resource input requirements for manufacturing volumes and transportation. Uncertainty associated with the efficacy of new technology such as CS over its required design life indicates that barrier replacement could increase its life cycle environmental impact above that of the cement barrier. Copyright © 2013 Elsevier B.V. All rights reserved.

PULLOUT BEHAVIOR OF OXYGEN PLASMA TREATED POLYMER FIBERS FROM CEMENT MATRIX

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Jan Trejbal

2017-11-01

Full Text Available The aim of this work is to describe bonding properties between surface treated polymer fibers and a cement matrix. In order to increase an interaction between the matrix and fiber surfaces, two fiber types having approx. 0.5 mm in diameter were modified by mean of oxygen plasma treatment. Surface physical changes of treated fibers were examined using SEM morphology observation and interfacial adhesion mechanical tests. The principle of mechanical tests rested on a single fiber pulling out from the matrix (cement paste, CEM I 42.5 R, w/c 0.4. The embedded length was equal to 50 % of original fiber length (50 mm, where the fiber free-end displacement and force resisting to the displacement were monitored. It was pointed out that interfacial shear stress needed to break the bond between the modified fibers and the matrix increased almost by 15–65 % if compared to reference fibers. When the fiber free-end displacement reached to 3.5 mm, the shear strength increased almost twice.

MODEL TESTS AND 3D ELASTIC FINITE ELEMENT ANALYSIS FOR STEEL PIPE PILES WITH WINGS IN STALLED IN SOIL CEMENT COLUMN

Science.gov (United States)

Tamai, Toshiyuki; Teramoto, Shuntarou; Kimura, Makoto

Steel pipe piles with wings installed in soil cement column is a composite foundation of pile consisting of soil improvement with cement and steel pipe with wings. This type of pile shows higher vertical bearing capacity when compared to steel pipe piles that are installed without soil cement. It is thought the wings contribute to higher bearing capacity of this type of piles. The wings are also thought to play the role of structural unification of pile foundations and load transfer. In this study, model test and 3D elastic finite element analysis was carried out in order to elucidate the effect of wings on the structural unification of pile foundation and the load transfer mechanism. Firstly, the model test was carried out in order to grasp the influence of pile with and without wings, the shape of wings of the pile and the unconfined compression strength of the soil cement on the structural unification of the pile foundation. The numerical analysis of the model test was then carried out on the intermediate part of the pile foundation with wings and mathematical model developed. Finally load tran sfer mechanism was checked for the entire length of the pile through this mathematical model and the load sharing ratio of the wings and stress distribution occurring in the soil cement clarified. In addition, the effect of the wing interval on the structural unification of the pile foundation and load transfer was also checked and clarified.

Cermet cements.

Science.gov (United States)

McLean, J W

1990-01-01

Cermet ionomer cements are sintered metal/glass powders, which can be made to react with poly(acids). These new cements are significantly more resistant to abrasion than regular glass ionomer cements and are widely accepted as core build-up materials and lining cements. They can strengthen teeth and provide the clinician with an opportunity to treat early dental caries.

Ground improvement using soil–cement columns: Experimental investigation

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Ahmed Farouk

2013-12-01

Full Text Available The construction of heavy structures on soils of low relative density is a challenging task. The inclusion of soil–cement columns produced by the deep mixing method is one of the soil stabilizing techniques that could be applied successfully to overcome this challenge. Nevertheless, this technique did not receive a considerable attention in Egypt yet. In the first part of this study, two different natural silty sand soils extracted from the Delta of the River Nile were mixed with cement to prepare samples of different cement doses and different water cement ratios. After curing, the hardened samples were tested and their unconfined compressive strength was investigated. The second part of this study investigates the interaction between a strip footing model and Nile deltaic soil improved by a group of soil–cement columns. Results of the first part of this study showed that the compressive strength of the investigated Nile delta soils could be increased even at lower values of cement doses. Results extracted from the second part of this study showed that a considerable settlement reduction up to 80% could be achieved depending on both the number and the length of the soil–cement columns that is used to improve the soil.

Hybrid life cycle assessment comparison of colloidal silica and cement grouted soil barrier remediation technologies

Energy Technology Data Exchange (ETDEWEB)

Gallagher, Patricia M., E-mail: pmg24@drexel.edu [Civil, Architectural and Environmental Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19038 (United States); Spatari, Sabrina; Cucura, Jeffrey [Civil, Architectural and Environmental Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19038 (United States)

2013-04-15

Highlights: ► We use LCA to study environmental impacts of grouting techniques for site remediation. ► We consider colloidal silica permeation grouting and cement jet grouting. ► Manufacturing and transportation contribute significantly in all impact categories. ► Activity outside of direct site activity is important in assessing impacts. ► LCA can be used to consider sustainability criteria for remediation decisions. -- Abstract: Site remediation involves balancing numerous costs and benefits but often neglects the environmental impacts over the entire project life cycle. Life cycle assessment (LCA) offers a framework for inclusion of global environmental “systems-level” decision metrics in combination with technological and cost analysis. We compare colloidal silica (CS) and cement grouted soil barrier remediation technologies for soils affected by low level radionuclides at a U.S. Superfund site using hybrid LCA methods. CS is a new, high performance grouting material installed using permeation grouting techniques. Cement, a more traditional grouting material, is typically installed using jet grouting techniques. Life cycle impacts were evaluated using the US EPA TRACI 2 model. Results show the highest life cycle environmental impacts for the CS barrier occur during materials production and transportation to the site. In general, the life cycle impacts for the cement barrier were dominated by materials production; however, in the extreme scenario the life cycle impacts were dominated by truck transportation of spoils to a distant, off-site radioactive waste facility. It is only in the extreme scenario tested in which soils are transported by truck (Option 2) that spoils waste transport dominates LCIA results. Life cycle environmental impacts for both grout barriers were most sensitive to resource input requirements for manufacturing volumes and transportation. Uncertainty associated with the efficacy of new technology such as CS over its required

Hybrid life cycle assessment comparison of colloidal silica and cement grouted soil barrier remediation technologies

International Nuclear Information System (INIS)

Gallagher, Patricia M.; Spatari, Sabrina; Cucura, Jeffrey

2013-01-01

Highlights: ► We use LCA to study environmental impacts of grouting techniques for site remediation. ► We consider colloidal silica permeation grouting and cement jet grouting. ► Manufacturing and transportation contribute significantly in all impact categories. ► Activity outside of direct site activity is important in assessing impacts. ► LCA can be used to consider sustainability criteria for remediation decisions. -- Abstract: Site remediation involves balancing numerous costs and benefits but often neglects the environmental impacts over the entire project life cycle. Life cycle assessment (LCA) offers a framework for inclusion of global environmental “systems-level” decision metrics in combination with technological and cost analysis. We compare colloidal silica (CS) and cement grouted soil barrier remediation technologies for soils affected by low level radionuclides at a U.S. Superfund site using hybrid LCA methods. CS is a new, high performance grouting material installed using permeation grouting techniques. Cement, a more traditional grouting material, is typically installed using jet grouting techniques. Life cycle impacts were evaluated using the US EPA TRACI 2 model. Results show the highest life cycle environmental impacts for the CS barrier occur during materials production and transportation to the site. In general, the life cycle impacts for the cement barrier were dominated by materials production; however, in the extreme scenario the life cycle impacts were dominated by truck transportation of spoils to a distant, off-site radioactive waste facility. It is only in the extreme scenario tested in which soils are transported by truck (Option 2) that spoils waste transport dominates LCIA results. Life cycle environmental impacts for both grout barriers were most sensitive to resource input requirements for manufacturing volumes and transportation. Uncertainty associated with the efficacy of new technology such as CS over its required

A treatment of expansive soil using different additives

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Bestun J. Nareeman

2010-11-01

Full Text Available There are many factors that govern the expansion behavior of soil. The primary factors are a change in water contentand the amount and type of clay size particles in the soil. Other important factors affecting the expansion behavior include the typeof soil (natural or fill, condition of the soil in terms of dry density and moisture content, magnitude of the surcharge pressure,and amount of no expansive material such as gravel or cobble size particles.In this paper, a swelling soil from the site Hamamuk earth dam, which is located in Koya town north of Iraq, is treated by fourtypes of additives; cement, steel fibers, gasoline fuel and injection by cement grout.The treatment of the expansive soil with 5 % of cement or steel fibers or the injection with cement grout revealed a betterimprovement while 4 % of gasoline oil is sufficient to reveal the optimum treatment by this material. The angle of internal friction is notaffected by the treatment while the cohesion between particles is slightly affected by these additives due to a change in the adhesionbetween the additive and soil particles.

Perioperative mortality in hip fracture patients treated with cemented and uncemented hemiprosthesis: a register study of 11,210 patients.

Science.gov (United States)

Talsnes, Ove; Vinje, Tarjei; Gjertsen, Jan Erik; Dahl, Ola E; Engesæter, Lars B; Baste, Valborg; Pripp, Are Hugo; Reikerås, Olav

2013-06-01

Adverse events associated with the use of bone cement for fixation of prostheses is a known complication. Due to inconclusive results in studies of hip fracture patients treated with cemented and uncemented hemiprostheses, this study was initiated. Our study is based on data reported to the Norwegian Hip Fracture Register on 11,210 cervical hip fractures treated with hemiprostheses (8,674 cemented and 2,536 uncemented). Significantly increased mortality within the first day of surgery was found in the cemented group (relative risk 2.9, 95 % confidence interval 1.6-5.1, p=0.001). The finding was robust giving the same results after adjusting for independent risk factors such as age, sex, cognitive impairment and comorbidity [American Society of Anesthesiologists (ASA) score]. For the first post-operative day the number needed to harm was 116 (one death for every 116 cemented prosthesis). However, in the most comorbid group (ASA worse than 3), the number needed to harm was only 33. We found increased mortality for the cemented hemiprosthesis the first post-operative day compared to uncemented procedures. This increased risk is closely related to patient comorbidity estimated by the patient's ASA score.

Effects of wood saw dust ash admixed with treated sisal fibre on the geotechnical properties of lateritic soil

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John Engbonye SANI

2017-12-01

Full Text Available The preliminary investigation conducted on the lateritic soil collected at Shika, Zaria shows that it falls under A-7-6 (10 classification for AASHTO (1986 and CL according to unified soil classification system USCS (ASTM 1992. The soil was treated with both wood saw dust ash (WSDA and treated sisal fiber, in stepped concentration of 0,2,4,6, and 8% for WSDA and 0, 0.25, 0.5, 0.75 and 1% treated sisal fibre by dry weight of soil using Standard proctor. The Sisal Fibre was treated with Sodium Borohydride (NaBH4 (1% wt/vol for 60 minutes at room temperature to remove the cellulose content present in the Fibre. Statistical analysis was carried out on the obtained results using XLSTART 2017 software and analysis of variance with the Microsoft Excel Analysis Tool Pak Software Package. The liquid limit (LL of the soil was found to be 48% while the plastic limit(PL is 21.27%. The maximum dry density(MDDhowever, decreases generally from a value of 1.85 Mg/m3 to 1.68Mg/m3 at 0.25% sisal fiber content/0% WSDA. It has its least value of 1.57Mg/m3 at 1% sisal fiber and 8% WSDA. The OMC increased from 18 % of the natural soil to 23.7% at 0.75% sisal fiber / 6% WSDA content. There was a general increase in the value of UCS of the soil-sisal fibre mixture with WSDA content from 100 kN/m2 of the natural soil to 696 kN/m2 at 0.75 % sisal fibre content / 6% WSDA. The UCS value met the standard of 687-1373 kN/m2 requirements of sub base for adequate lime and cement stabilization, respectively (Ingas and Metcalf 1972.

Microbial Activity in Peat Soil Treated With Ordinary Portland Cement (OPC) and Coal Ashes

Science.gov (United States)

Rahman, J. A.; Mohamed, R. M. S. R.; Al-Gheethi, A. A.

2018-04-01

Peat soil is a cumulative of decayed plant fragment which developed as a result of microbial activity. The microbes degrade the organic matter in the peat soils by the production of hydrolysis enzyme. The least decomposed peat, known as fibric peat has big particles and retain lots of water. This made peat having high moisture content, up to 1500 %. The most decomposed peat known as sapric peat having fines particles and less void ratio. The present study aimed to understand the effects of solidification process on the bacterial growth and cellulase (CMCase) enzyme activity. Two types of mixing were designed for fibric, hemic and sapric peats; (i) Ordinary Portland cement (OPC) at an equal amount of dry peat, with 25 % of fly ash (FA) and total of coarse particle, a combination of bottom ash and fibre of 22 – 34 %, (ii) fibric peat was using water-to-binder ratio (w/b) = 1, 50% OPC, 25 % bottom ash (BA) and 25 % FA. For hemic and sapric peat, w/b=3 with 50 % OPC and 50 % BA were used. All samples were prepared triplicates, and were cured for 7, 14, 28 and 56 days in a closed container at room temperature. The results revealed that the first mix design giving a continuous strength development. However, the second mix design shows a decreased in strength pattern after day 28. The influence of the environment factors such as alkaline pH, reduction of the water content and peat temperature has no significant on the reduction amount of native microbes in the peat. The microbes survived in the solidified peat but the amount of microbes were found reduced for all types of mixing Fibric Mixed 1 (FM1), Hemic Mixed 1(HM1) and Sapric Mixed 1 (SM1) were having good strength increment for about 330 – 1427 % with enzymatic activity recorded even after D56. Nevertheless, with increase in the strength development through curing days, the enzymatic activities were reduced. For the time being, it can be concluded that the microbes have the ability to adapt with new environment

Cement Stabilized Soil Blocks Admixed with Sugarcane Bagasse Ash

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Jijo James

2016-01-01

Full Text Available The study involved investigating the performance of ordinary Portland cement (OPC stabilized soil blocks amended with sugarcane bagasse ash (SBA. Locally available soil was tested for its properties and characterized as clay of medium plasticity. This soil was stabilized using 4% and 10% OPC for manufacture of blocks of size 19 cm × 9 cm × 9 cm. The blocks were admixed with 4%, 6%, and 8% SBA by weight of dry soil during casting, with plain OPC stabilized blocks acting as control. All blocks were cast to one target density and water content followed by moist curing for a period of 28 days. They were then subjected to compressive strength, water absorption, and efflorescence tests in accordance with Bureau of Indian standards (BIS specifications. The results of the tests indicated that OPC stabilization resulted in blocks that met the specifications of BIS. Addition of SBA increased the compressive strength of the blocks and slightly increased the water absorption but still met the standard requirement of BIS code. It is concluded that addition of SBA to OPC in stabilized block manufacture was capable of producing stabilized blocks at reduced OPC content that met the minimum required standards.

Thermal and mechanical properties of NaOH treated hemp fabric and calcined nanoclay-reinforced cement nanocomposites

International Nuclear Information System (INIS)

Hakamy, A.; Shaikh, F.U.A.; Low, I.M.

2015-01-01

Highlights: • Fabrication of nanoclay and hemp fabric-reinforced cement composites. • The optimum nanoclay and hemp fabric content is 1.0 and 6.9 wt.% respectively. • Surface-treated hemp fabric-reinforced cement composites demonstrated better mechanical properties. • Surface modification of hemp fabric was effective in improving the hemp fabric-cement matrix adhesion. - Abstract: Cement nanocomposites reinforced with hemp fabrics and calcined nanoclay (CNC) have been fabricated and investigated. CNC is prepared by heating nanoclay (Cloisite 30B) at 900 °C for 2 h. The influences of CNC dispersion on the mechanical properties and thermal properties of these composites have been characterized in terms of porosity, density, water absorption, flexural strength, fracture toughness, impact strength and thermal stability. The microstructure is investigated using Quantitative X-ray Diffraction Analysis (QXDA) and High Resolution Transmission Electron Microscopy (HRTEM). The effects of alkali (NaOH) treatment of hemp fabric on the mechanical properties of hemp fabric-reinforced cement composites with different fabric contents of 4.5, 5.7, 6.9 and 8.1 wt% are also investigated. Results show that the optimum hemp fabric content is 6.9 wt% (i.e. 6 fabric layers). Results also indicated that physical, mechanical and thermal properties were enhanced due to the addition of CNC into the cement matrix and the optimum content of CNC was 1 wt%. The treated hemp fabric-reinforced nanocomposites containing 1 wt% CNC exhibited the highest flexural strength, fracture toughness, impact strength and thermal stability by virtue of good fibre–matrix interface. This environmentally friendly nanocomposite can be used for various construction applications such as ceilings and roofs

Settlement Control of Soft Ground using Cement-Ricehusk Stabilization

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Mokhtar M.

2012-01-01

Full Text Available Cement is widely used for improvement of soft soils, but financial and environmental concerns are causing genuine concerns to all parties, leading to the quest for alternative and effective stabilizers. Ricehusk is an agricultural waste in Malaysia, commonly disposed of by open burning or dumping in landfills. Considering that the ashes derived from ricehusk are pozzolanic in nature, there is a possibility that a cement-ricehusk mixture could effectively improve soft soils with reduced cement dosage. This study examines the mixture’s effectiveness by monitoring the settlement reduction in a clay soil. Standard oedometer tests were carried out on a soft marine clay sample admixed with cement-ricehusk. Test specimens contained 0-10% cement and 0-5% of ricehusk respectively, and were left to cure for either seven or 28 days. The stabilized specimens were observed to undergo significant reduction in compressibility, verifying the potential of cement-ricehusk as an alternative soft soil stabilizer.

Efficiency of Micro-fine Cement Grouting in Liquefiable Sand

International Nuclear Information System (INIS)

Mirjalili, Mojtaba; Mirdamadi, Alireza; Ahmadi, Alireza

2008-01-01

In the presence of strong ground motion, liquefaction hazards are likely to occur in saturated cohesion-less soils. The risk of liquefaction and subsequent deformation can be reduced by various ground improvement methods including the cement grouting technique. The grouting method was proposed for non-disruptive mitigation of liquefaction risk at developed sites susceptible to liquefaction. In this research, a large-scale experiment was developed for assessment of micro-fine cement grouting effect on strength behavior and liquefaction potential of loose sand. Loose sand samples treated with micro-fine grout in multidirectional experimental model, were tested under cyclic and monotonic triaxial loading to investigate the influence of micro-fine grout on the deformation properties and pore pressure response. The behavior of pure sand was compared with the behavior of sand grouted with a micro-fine cement grout. The test results were shown that cement grouting with low concentrations significantly decreased the liquefaction potential of loose sand and related ground deformation

Assessment of cement kiln dust (CKD) for stabilization/solidification (S/S) of arsenic contaminated soils.

Science.gov (United States)

Moon, Deok Hyun; Wazne, Mahmoud; Yoon, In-Ho; Grubb, Dennis G

2008-11-30

A stabilization/solidification (S/S) process for arsenic (As) contaminated soils was evaluated using cement kiln dust (CKD). Laboratory-prepared slurries, made of either kaolinite or montmorillonite, and field soils spiked with either As(3+) or As(5+) were prepared and treated with CKD ranging from 10 to 25 wt%. Sodium arsenite and sodium arsenate at 0.1 wt% were used to simulate arsenite (As(3+)) and arsenate (As(5+)) source contamination in soils, respectively. The effectiveness of treatment was evaluated at curing periods of 1- and 7-days based on the toxicity characteristic leaching procedure (TCLP). As-CKD and As-clay-CKD slurries were also spiked at 10 wt% to evaluate As immobilization mechanism using X-ray powder diffraction (XRPD) analyses. Overall, the TCLP results showed that only the As(5+) concentrations in kaolinite amended with 25 wt% CKD after 1 day of curing were less than the TCLP regulatory limit of 5mg/L. Moreover, at 7 days of curing, all As(3+) and As(5+) concentrations obtained from kaolinite soils were less than the TCLP criteria. However, none of the CKD-amended montmorillonite samples satisfied the TCLP-As criteria at 7 days. Only field soil samples amended with 20 wt% CKD complied with the TCLP criteria within 1 day of curing, where the source contamination was As(5+). XRPD and scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX) results showed that Ca-As-O and NaCaAsO(4).7.5H(2)O were the primary phases responsible for As(3+) and As(5+) immobilization in the soils, respectively.

Assessment of cement kiln dust (CKD) for stabilization/solidification (S/S) of arsenic contaminated soils

International Nuclear Information System (INIS)

Moon, Deok Hyun; Wazne, Mahmoud; Yoon, In-Ho; Grubb, Dennis G.

2008-01-01

A stabilization/solidification (S/S) process for arsenic (As) contaminated soils was evaluated using cement kiln dust (CKD). Laboratory-prepared slurries, made of either kaolinite or montmorillonite, and field soils spiked with either As 3+ or As 5+ were prepared and treated with CKD ranging from 10 to 25 wt%. Sodium arsenite and sodium arsenate at 0.1 wt% were used to simulate arsenite (As 3+ ) and arsenate (As 5+ ) source contamination in soils, respectively. The effectiveness of treatment was evaluated at curing periods of 1- and 7-days based on the toxicity characteristic leaching procedure (TCLP). As-CKD and As-clay-CKD slurries were also spiked at 10 wt% to evaluate As immobilization mechanism using X-ray powder diffraction (XRPD) analyses. Overall, the TCLP results showed that only the As 5+ concentrations in kaolinite amended with 25 wt% CKD after 1 day of curing were less than the TCLP regulatory limit of 5 mg/L. Moreover, at 7 days of curing, all As 3+ and As 5+ concentrations obtained from kaolinite soils were less than the TCLP criteria. However, none of the CKD-amended montmorillonite samples satisfied the TCLP-As criteria at 7 days. Only field soil samples amended with 20 wt% CKD complied with the TCLP criteria within 1 day of curing, where the source contamination was As 5+ . XRPD and scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX) results showed that Ca-As-O and NaCaAsO 4 .7.5H 2 O were the primary phases responsible for As 3+ and As 5+ immobilization in the soils, respectively

Evaluation of deformation-strength characteristics of Fiber-cement-stabilized soil by using Distinct Element Method

Science.gov (United States)

Satomi, Tomoaki; Konda, Naoki; Takahashi, Hiroshi

Fiber-cement-stabilized soil method is an effective way to recycle high-water content mud. The modified soil has several advantages such as high failure stress and high failure strain. However, the quality of the modified soil is not constant and depends on the water content of the mud and additives. Therefore, experimental verification to obtain the strength characteristics of the modified soil is necessary, but conducting experiments under various conditions is ineffective and uneconomic. In this study, a numerical model to estimate deformation-strength characteristics of the modified soil is investigated by using Distinct Element Method (DEM). It was shown that the developed model was effective way to estimate deformation-strength characteristics. Moreover, it was confirmed that the modified soil had high earthquake resistance.

Erodibility of cement-stabilized tropical soils in highway engineering in Togo

International Nuclear Information System (INIS)

Eklu-Natey, T.E.D.

1992-01-01

This work contains a methodical study on the suceptibility to weather of cement-stabilized tropical soils of Togo by simulating on the one hand the climatic conditions of the original surroundings and on the other hand the variations occuring in situ of the degree of saturation and compaction. The chosen tests ensure for the first time a simple execution and at the same time reproducible numerical values of the results achieved. From results of the slaking, erosion, adhesion, durability and swelling tests clear parameters and classification criteria were derived which help to forecast the susceptibility to weather of soils in tropical climates. A method for the determination of the reaction to water of soils is proposed consisting of a particular process of derivation and interpretation of the consistency value for a given swelling rate. Moreover a possibility is recommended with which the time-consuming and expensive mineralogical analyses which were frequently used in the past for torpical soils can be avoided. The proposed evaluation criteria provides civil engineers working in permanently moist, arid or intermittently moist tropical regions with practical and theoretical bases for the estimation of the erodibility of soils. (orig./BBR) [de

Experimental study of silty clay stabilization with cement and lime in multan, pakistan

International Nuclear Information System (INIS)

Sultan, T.

2014-01-01

Stabilization is valuable substitute for advancing the soil characteristics. The engineering features gained after stabilization differs broadly owing to non-uniformity in constitutions of soil. This study describes an assessment of cement and lime additives for advancing soils ventures. The effectiveness of lime and cement stabilization on geotechnical characteristics of the in situ soil has also been described in the paper. The additives like cement and lime were added in different dosage rates to examine the change in properties of the in situ soil. Cement addition caused an increase in unconfined compression strength (UCS) throughout from 4% to 16% of cement. Moreover, it has been observed that by adding lime, the early strength of clay increases up to 6% of lime but for long term strength i.e. 28 days maximum strengths is achieved for 4% of lime. It also confirms that with more percentage of lime and longer duration of curing, it expands. In addition to the strength behavior of samples at various percentages of cement and lime, the deflection at failure point was also examined. In order to make a straight comparison, both cement and lime stabilized soils were also tested in laboratory. Generally, the performance of Portland cement-stabilized soils was advanced to lime in the experiments performed. (author)

Physical, chemical and mineralogical characterization of water treatment plant waste for use in soil-cement brick

International Nuclear Information System (INIS)

Pessin, L.R.; Destefani, A.Z.; Holanda, J.N.F.

2011-01-01

The water treatment plants (WTP) for human consumption generate huge amounts of waste in the form of sludge (sludge) that have been over the years mostly inadequately prepared in water resources and the environment. Moreover, traditional methods of disposal of waste water treatment plants commonly used are generally costly activities. An alternative method for disposal of this waste abundant is its incorporation in ceramic products. This work is focused on the physical-chemical and mineralogical composition of a sample of waste water treatment plants from the region of Campos dos Goytacazes-RJ to their use in the manufacture of soil-cement brick. Several characterization techniques were used including X-ray diffraction, X-ray fluorescence, scanning electron microscopy, picnometry, particle size analysis and plasticity. The experimental results indicate that the waste water treatment plants have the potential to be used in the manufacture of ecologic soil-cement bricks. (author)

ALTERNATIVE FIELD METHODS TO TREAT MERCURY IN SOIL

Energy Technology Data Exchange (ETDEWEB)

Ernest F. Stine Jr; Steven T. Downey

2002-08-14

simulate expected ranges of mercury contamination and to increase the TCLP mercury values. IT/NFS investigated ambient temperature amalgamation/stabilization/fixation of mercury-contaminated soils to meet these objectives. Treatment ranged in size from a few ounces to 10 pounds. The treatability study philosophy was to develop working envelops of formulations where reasonable minimum and maximum amounts of each reagent that would successfully treat the contaminated soil were determined. The dosages investigated were based on ratios of stoichiometric reactions and applications of standard sets of formulations. The approach purposely identified formulations that failed short or longer cure-time performance criteria to define the limits of the envelope. Reagent envelops successfully met the project requirements one day after treatment and after greater than 30-day cures. The use of multiple levels of spikes allowed the establishment of reagent dosages that were successful across a broad range of mercury values, e.g., 50 to 6000 mg/kg mercury. The treatment products were damp to slightly wet material. Enough drying reagent, e.g., Portland cement or lime by-product, were added to some formulations to control the leachability of uranium and other hazardous metals and to ensure the product passed the paint filter test. Cost analyzes and conceptual designs for four alternatives for full-scale treatments were prepared. The alternatives included two in-situ treatments and two ex-situ treatments. The cost estimates were based on the results from the bench-scale study. All four alternatives treatment costs were well below the baseline costs.

Leaf structural traits of tropical woody species resistant to cement dust.

Science.gov (United States)

Siqueira-Silva, Advanio Inácio; Pereira, Eduardo Gusmão; Modolo, Luzia Valentina; Paiva, Elder Antonio Sousa

2016-08-01

Cement industries located nearby limestone outcrops in Brazil have contributed to the coating of cement dust over native plant species. However, little is known about the extent of the response of tropical woody plants to such environmental pollutant particularly during the first stages of plant development and establishment. This work focused on the investigation of possible alterations in leaf structural and ultrastructural traits of 5-month-old Guazuma ulmifolia Lam. (Malvaceae), 6-month-old Myracrodruon urundeuva Allemão (Anacardiaceae), and 9-month-old Trichilia hirta L. (Meliaceae) challenged superficially with cement dust during new leaf development. Leaf surface of plants, the soil or both (leaf plus soil), were treated (or not) for 60 days, under controlled conditions, with cement dust at 2.5 or 5.0 mg cm(-2). After exposure, no significant structural changes were observed in plant leaves. Also, no plant death was recorded by the end of the experiment. There was also some evidence of localized leaf necrosis in G. ulmifolia and T. hirta, leaf curling in M. urundeuva and T. hirta, and bulges formation on epidermal surface of T. hirta, after cement dust contact with plant shoots. All species studied exhibited stomata obliteration while T. hirta, in particular, presented early leaf abscission, changes in cellular relief, and organization and content of midrib cells. No significant ultrastructural alterations were detected under the experimental conditions studied. Indeed, mesophyll cells presented plastids with intact membrane systems. The high plant survival rates, together with mild morphoanatomic traits alterations in leaves, indicate that G. ulmifolia is more resistant to cement dust pollutant, followed by M. urundeuva and T. hirta. Thus, the three plant species are promising for being used to revegetate areas impacted by cement industries activities.

Recycling stabilised/solidified drill cuttings for forage production in acidic soils.

Science.gov (United States)

Kogbara, Reginald B; Dumkhana, Bernard B; Ayotamuno, Josiah M; Okparanma, Reuben N

2017-10-01

Stabilisation/solidification (S/S), which involves fixation and immobilisation of contaminants using cementitious materials, is one method of treating drill cuttings before final fate. This work considers reuse of stabilised/solidified drill cuttings for forage production in acidic soils. It sought to improve the sustainability of S/S technique through supplementation with the phytoremediation potential of plants, eliminate the need for landfill disposal and reduce soil acidity for better plant growth. Drill cuttings with an initial total petroleum hydrocarbon (TPH) concentration of 17,125 mg kg -1 and low concentrations of metals were treated with 5%, 10%, and 20% cement dosages. The treated drill cuttings were reused in granular form for growing a forage, elephant grass (Pennisetum purpureum), after mixing with uncontaminated soil. The grasses were also grown in uncontaminated soil. The phytoremediation and growth potential of the plants was assessed over a 12-week period. A mix ratio of one part drill cuttings to three parts uncontaminated soil was required for active plant growth. The phytoremediation ability of elephant grass (alongside abiotic losses) reduced the TPH level (up to 8795 mg kg -1 ) in the soil-treated-drill cuttings mixtures below regulatory (1000 mg kg -1 ) levels. There were also decreased concentrations of metals. The grass showed better heights and leaf lengths in soil containing drill cuttings treated with 5% cement dosage than in uncontaminated soil. The results suggest that recycling S/S treated drill cuttings for forage production may be a potential end use of the treated waste. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mechanical Behaviour of Soil Improved by Alkali Activated Binders

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Enza Vitale

2017-11-01

Full Text Available The use of alkali activated binders to improve engineering properties of clayey soils is a novel solution, and an alternative to the widely diffused improvement based on the use of traditional binders such as lime and cement. In the paper the alkaline activation of two fly ashes, by-products of coal combustion thermoelectric power plants, has been presented. These alkali activated binders have been mixed with a clayey soil for evaluating the improvement of its mechanical behaviour. One-dimensional compression tests on raw and treated samples have been performed with reference to the effects induced by type of binder, binder contents and curing time. The experimental evidences at volume scale of the treated samples have been directly linked to the chemo-physical evolution of the binders, investigated over curing time by means of X Ray Diffraction. Test results showed a high reactivity of the alkali activated binders promoting the formation of new mineralogical phases responsible for the mechanical improvement of treated soil. The efficiency of alkali activated binders soil treatment has been highlighted by comparison with mechanical performance induced by Portland cement.

Bamboo leaf ash as the stabilizer for soft soil treatment

Science.gov (United States)

Rahman, A. S. A.; Jais, I. B. M.; Sidek, N.; Ahmad, J.; Rosli, M. I. F.

2018-04-01

Soft soil is a type of soil that have the size of particle less than 0.063mm. The strength of the soft soil does not fulfil the requirement for construction. The present of soft soil at the construction site always give a lot of problems and issues to geotechnical sector. Soil settlement is one of the problems that related to soft soil. The determination of the soft soil physical characteristics will provide a detail description on its characteristic. Soft soil need to be treated in order to gain the standard strength for construction. One of the method to strengthen the soft soil is by using pozzolanic material as a treatment method for soft soil. Furthermore bamboo leaf ash is one of the newly founded materials that contain pozzolanic material. Any material that consist of Silicon Dioxide (SiO2) as the main component and followed by Aluminium Oxide (Al2O3) and Iron Oxide (Fe2O3) are consider as pozzolanic material. Bamboo leaf ash is mix with the cement as the treatment material. Bamboo leaf ash will react with the cement to produce additional cement binder. Thus, it will increase the soil strength and will ease the geotechnical sector to achieve high quality of construction product.

Cement stabilization of hazardous and radioactive electroplating sludge

International Nuclear Information System (INIS)

Langton, C.A.; Pickett, J.B.; Martin, M.L.

1991-01-01

Cement stabilization was evaluated for treatment of nickel and uranium in electroplating sludge at the Savannah River Site. Waste forms were prepared by pretreating the sludge and the solidifying it in a variety of cement, cement plus flyash, and cement-flyash-slag mixes. The sludge was also treated by one-step filtration-solidification. Leaching results and processing data indicate the cement solidification is an effective method of treating hazardous-low-level electroplating waste

Effect of Rice Husk Ash on Cement Stabilized Laterite

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Musa ALHASSAN

2007-09-01

Full Text Available Laterite soil collected from Maikunkele area of Minna, classified as an A-7-6 on AASHTO classification, was stabilized with 2-8% cement by weight of the dry soil. Using British Standard Light (BSL compaction energy, the effect of Rice Husk Ash (RHA on the soil was investigated with respect to compaction characteristics, California Bearing Ratio (CBR and Unconfined Compressive Strength (UCS tests. Results obtained, indicate a general decrease in Maximum Dry Density (MDD and increase in Optimum Moisture Content (OMC, all with increase in RHA Content (2-8% at specified cement contents. There was also a tremendous improvement in the CBR and UCS with increase in the RHA content at specified cement contents to their peak values at between 4-6% RHA. The UCS values also improved with curing age. This indicates the potentials of using 4-6% RHA admixed with less cement contents for laterite soil stabilization.

Cement Mason's Curriculum. Instructional Units.

Science.gov (United States)

Hendirx, Laborn J.; Patton, Bob

To assist cement mason instructors in providing comprehensive instruction to their students, this curriculum guide treats both the skills and information necessary for cement masons in commercial and industrial construction. Ten sections are included, as follow: related information, covering orientation, safety, the history of cement, and applying…

Permeability Characteristics of Compacted and Stabilized Clay with Cement, Peat Ash and Silica Sand

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Seyed Esmaeil Mousavi

2016-06-01

Full Text Available The present paper investigates the influence of stabilization with cement, peat ash, and silica sand on permeability coefficient (kv of compacted clay, using a novel approach to stabilize the clay with peat ash as a supplementary material of cement in the compacted and stabilized soil. In order to assess the mentioned influence, test specimens of both untreated and stabilized soil have been tested in the laboratory so that their permeability could be evaluated. Falling head and one dimensional consolidation tests of laboratory permeability were performed on the clay specimens and the chemical compositions of the materials as well as microstructure of the stabilized soil with 18% cement, 2% peat ash, and 5% silica sand were investigated, using X-ray fluorescence and scanning electron microscopy respectively. Results show that for soil stabilization with up to 8% cement content (of the dry weight of the soil, the average value of coefficient of permeability (kv is very close to that of untreated soil, whereas the kv value decreases drastically for 18% cement under identical void ratio conditions. It is further revealed that addition of 18% cement, 2% peat ash, and 5% silica sand had decreased the coefficient of permeability by almost 2.2 folds after 24 h, while about 1.7 folds increase was observed in coefficient of permeability once 13.5% of cement, 1.5% of peat ash, and 20% of silica sand were added. The partial replacement of cement with the 2% peat ash can reduce the consumption of cement for soil stabilization.

Resistance to bond degradation between dual-cure resin cements and pre-treated sintered CAD-CAM dental ceramics

Science.gov (United States)

Osorio, Raquel; Monticelli, Francesca; Osorio, Estrella; Toledano, Manuel

2012-01-01

Objective: To evaluate the bond stability of resin cements when luted to glass-reinforced alumina and zirconia CAD/CAM dental ceramics. Study design: Eighteen glass-infiltrated alumina and eighteen densely sintered zirconia blocks were randomly conditioned as follows: Group 1: No treatment; Group 2: Sandblasting (125 µm Al2O3-particles); and Group 3: Silica-coating (50 µm silica-modified Al2O3-particles). Composite samples were randomly bonded to the pre-treated ceramic surfaces using different resin cements: Subgroup 1: Clearfil Esthetic Cement (CEC); Subgroup 2: RelyX Unicem (RXU); and Subgroup 3: Calibra (CAL). After 24 h, bonded specimens were cut into 1 ± 0.1 mm2 sticks. One-half of the beams were tested for microtensile bond strength (MTBS). The remaining one-half was immersed in 10 % NaOCl aqueous solution (NaOClaq) for 5 h before testing. The fracture pattern and morphology of the debonded surfaces were assessed with a field emission gun scanning electron microscope (FEG-SEM). A multiple ANOVA was conducted to analyze the contributions of ceramic composition, surface treatment, resin cement type, and chemical challenging to MTBS. The Tukey test was run for multiple comparisons (p ceramic interfacial longevity depended on cement selection rather than on surface pre-treatments. The MDP-containing and the self-adhesive resin cements were both suitable for luting CAD/CAM ceramics. Despite both cements being prone to degradation, RXU luted to zirconia or untreated or sandblasted alumina showed the most stable interfaces. CAL experimented spontaneous debonding in all tested groups. Key words:CAD/CAM ceramic, alumina, zirconia, resin cement, surface pre-treatment, sandblasting, silica-coating, chemical aging, bond degradation, microtensile bond strength. PMID:22322517

The cement solidification systems at LANL

International Nuclear Information System (INIS)

Veazey, G.W.

1990-01-01

There are two major cement solidification systems at Los Alamos National Laboratory. Both are focused primarily around treating waste from the evaporator at TA-55, the Plutonium Processing Facility. The evaporator receives the liquid waste stream from TA-55's nitric acid-based, aqueous-processing operations and concentrates the majority of the radionuclides in the evaporator bottoms solution. This is sent to the TA-55 cementation system. The evaporator distillate is sent to the TA-50 facility, where the radionuclides are precipitated and then cemented. Both systems treat TRU-level waste, and so are operated according to the criteria for WIPP-destined waste, but they differ in both cement type and mixing method. The TA-55 systems uses Envirostone, a gypsum-based cement and in-drum prop mixing; the TA-50 systems uses Portland cement and drum tumbling for mixing

Bond strength of resin cement to CO2 and Er:YAG laser-treated zirconia ceramic

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Shahin Kasraei

2014-11-01

Full Text Available Objectives It is difficult to achieve adhesion between resin cement and zirconia ceramics using routine surface preparation methods. The aim of this study was to evaluate the effects of CO2 and Er:YAG laser treatment on the bond strength of resin cement to zirconia ceramics. Materials and Methods In this in-vitro study 45 zirconia disks (6 mm in diameter and 2 mm in thickness were assigned to 3 groups (n = 15. In control group (CNT no laser treatment was used. In groups COL and EYL, CO2 and Er:YAG lasers were used for pretreatment of zirconia surface, respectively. Composite resin disks were cemented on zirconia disk using dual-curing resin cement. Shear bond strength tests were performed at a crosshead speed of 0.5 mm/min after 24 hr distilled water storage. Data were analyzed by one-way ANOVA and post hoc Tukey's HSD tests. Results The means and standard deviations of shear bond strength values in the EYL, COL and CNT groups were 8.65 ± 1.75, 12.12 ± 3.02, and 5.97 ± 1.14 MPa, respectively. Data showed that application of CO2 and Er:YAG lasers resulted in a significant higher shear bond strength of resin cement to zirconia ceramics (p < 0.0001. The highest bond strength was recorded in the COL group (p < 0.0001. In the CNT group all the failures were adhesive. However, in the laser groups, 80% of the failures were of the adhesive type. Conclusions Pretreatment of zirconia ceramic via CO2 and Er:YAG laser improves the bond strength of resin cement to zirconia ceramic, with higher bond strength values in the CO2 laser treated samples.

The effect of portland cement for solidification of soils contaminated by mine tailings containing heavy metals

Science.gov (United States)

Jian-Jun, Chen; Zheng-Miao, Xie

2010-05-01

Portland cement(PC) was used to solidify the lead-zinc mine tailings contaminated soils(CS) in this work. The soils were heavily polluted by heavy metals with lead(up to 19592 mg/kg), zinc(up to 647mg/kg), Cd(up to 14.65mg.kg) and Cu(up to 287mg/kg). Solidified/stabilized(s/s)forms with a range of cement contents, 40-90 wt%, were evaluated to determine the optimal binder content. Unconfined compression strength test(UCS), Chinese solid waste-extraction procedure for leaching toxicity - Horizontal vibration method, toxicity characteristic leaching procedures(TCLP) were used for physical and chemical characterization of the s/s forms. The procedure of Tessier et al.(1979) was used to separate S/S forms Pb, Zn, Cd, Cu into different fractions. The results show that addition of 50% cement was enough for the s/s forms to satisfy the MU10 requirements (0.10 MPa). Under the 50% addition, the content of the water-exchangeable fraction of Pb reduced from 2.25% to 0.2%, the carbonate-bound fraction and organic-bound fraction reduced by about half, while the Fe-Mn oxide-bound fraction was more than doubled. The residual fraction decreased 8% on the contrary. For Zn, except for the carbonate-bound fraction increased slightly, the features of other items were same as that of Pb. For Cd, the water-exchangeable fraction was reduced largely, the residual fraction and Fe-Mn oxide-bound fraction increased 2-3%. For Cu, A distinct feature is the organic-bound fraction reduced with the reduction in consumption of cement, at the same time, the residual fraction increased corresponding. Leaching test results indicate that the leaching contents of Pb2+ of the six specimens are quite different at low pH value(

Instability improvement of the subgrade soils by lime addition at Borg El-Arab, Alexandria, Egypt

Science.gov (United States)

El Shinawi, A.

2017-06-01

Subgrade soils can affect the stability of any construction elsewhere, instability problems were found at Borg El-Arab, Alexandria, Egypt. This paper investigates geoengineering properties of lime treated subgrade soils at Borg El-Arab. Basic laboratory tests, such as water content, wet and dry density, grain size, specific gravity and Atterberg limits, were performed for twenty-five samples. Moisture-density (compaction); California Bearing Ratio (CBR) and Unconfined Compression Strength (UCS) were conducted on treated and natural soils. The measured geotechnical parameters of the treated soil shows that 6% lime is good enough to stabilize the subgrade soils. It was found that by adding lime, samples shifted to coarser side, Atterberg limits values of the treated soil samples decreased and this will improve the soil to be more stable. On the other hand, Subgrade soils improved as a result of the bonding fine particles, cemented together to form larger size and reduce the plastiCity index which increase soils strength. The environmental scanning electron microscope (ESEM) is point to the presence of innovative aggregated cement materials which reduce the porosity and increase the strength as a long-term curing. Consequently, the mixture of soil with the lime has acceptable mechanical characteristics where, it composed of a high strength base or sub-base materials and this mixture considered as subgrade soil for stabilizations and mitigation the instability problems that found at Borg Al-Arab, Egypt.

Soil enzyme dynamics in chlorpyrifos-treated soils under the influence of earthworms.

Science.gov (United States)

Sanchez-Hernandez, Juan C; Notario Del Pino, J; Capowiez, Yvan; Mazzia, Christophe; Rault, Magali

2018-01-15

Earthworms contribute, directly and indirectly, to contaminant biodegradation. However, most of bioremediation studies using these annelids focus on pollutant dissipation, thus disregarding the health status of the organism implied in bioremediation as well as the recovery of indicators of soil quality. A microcosm study was performed using Lumbricus terrestris to determine whether earthworm density (2 or 4individuals/kg wet soil) and the time of exposure (1, 2, 6, 12, and 18wk) could affect chlorpyrifos persistence in soil initially treated with 20mg active ingredientkg -1 wet soil. Additionally, selected earthworm biomarkers and soil enzyme activities were measured as indicators of earthworm health and soil quality, respectively. After an 18-wk incubation period, no earthworm was killed by the pesticide, but clear signs of severe intoxication were detected, i.e., 90% inhibition in muscle acetylcholinesterase and carboxylesterase (CbE) activities. Unexpectedly, the earthworm density had no significant impact on chlorpyrifos dissipation rate, for which the measured half-life ranged between 30.3d (control soils) and 44.5d (low earthworm density) or 36.7d (high earthworm density). The dynamic response of several soil enzymes to chlorpyrifos exposure was examined calculating the geometric mean and the treated-soil quality index, which are common enzyme-based indexes of microbial functional diversity. Both indexes showed a significant and linear increase of the global enzyme response after 6wk of chlorpyrifos treatment in the presence of earthworms. Examination of individual enzymes revealed that soil CbE activity could decrease chlorpyrifos-oxon impact upon the rest of enzyme activities. Although L. terrestris was found not to accelerate chlorpyrifos dissipation, a significant increase in the activity of soil enzyme activities was achieved compared with earthworm-free, chlorpyrifos-treated soils. Therefore, the inoculation of organophosphorus-contaminated soils with L

Petroleum Sludge as gypsum replacement in cement plants: Its Impact on Cement Strength

Science.gov (United States)

Benlamoudi, Ali; Kadir, Aeslina Abdul; Khodja, Mohamed

2017-08-01

Due to high cost of cement manufacturing and the huge amount of resources exhaustion, companies are trying to incorporate alternative raw materials or by-products into cement production so as to produce alternative sustainable cement. Petroleum sludge is a dangerous waste that poses serious imparts on soil and groundwater. Given that this sludge contains a high percentage of anhydrite (CaSO4), which is the main component of gypsum (CaSO4.2H2O), it may play the same gypsum role in strength development. In this research, a total replacement of gypsum (100%) has been substituted by petroleum sludge in cement production and has led to an increase of 28.8% in UCS values after 28 curing days. Nevertheless, the burning of this waste has emitted a considerable amount of carbon monoxide (CO) gas that needs to be carefully considered prior to use petroleum sludge within cement plants.

Resistência à compressão do solo-cimento com substituição parcial do cimento Portland por resíduo cerâmico moído Compressive strength of soil-cement with partial replacement of the Portland cement by crushed ceramic waste

Directory of Open Access Journals (Sweden)

Rivanildo Dallacort

2002-12-01

Full Text Available Neste trabalho, apresenta-se o estudo experimental da resistência à compressão do solo-cimento, com substituição parcial do cimento Portland por resíduo cerâmico moído. Para tanto, foram ensaiados 81 espécimenes cilíndricos desse material à compressão, em que parte do cimento foi substituída por material cerâmico moído. Realizou-se uma programação fatorial, na qual três variáveis foram selecionadas para estudo: o teor de material ligante (cimento + resíduo cerâmico, a umidade do solo e o teor de resíduo cerâmico adicionado. É apresentado um estudo estatístico através de análise de variância da massa específica do material e da resistência a compressão. Tal estudo permitiu concluir-se que substituições de 25 e 57% do teor de cimento por material cerâmico podem produzir blocos de solo-cimento com resistências superiores a 2 MPa, com teor de material ligante de 6 e 8%, respectivamente.In this paper, an experimental study of the compressive strength of soil-cement with partial replacement of the Portland cement by crushed ceramic waste is presented and discussed. For this, eighty-one cylindrical specimens of soil-cement were tested, where part of cement percentage was replaced by crushed ceramic waste. The experiment was conducted in factorial design and three variables were selected and studied: the binding material content (cement + ceramic waste, soil moisture content and the ratio of ceramic waste. A statistical study using variance analysis of the specific mass and compressive strength of the material is presented. This study concluded that replacement ratios of 25 and 57% of the Portland cement by crushed ceramic material can be used to fabricate soil-cement bricks with strength higher than 2 MPa, for a binding material content of 6 and 8% respectively.

experimental study of cement grout: rheological behavior and sedimentation

OpenAIRE

Rosquoët , Frédéric; Alexis , Alain ,; Khelidj , Abdelhafid; Phelipot-Mardelé , Annabelle

2002-01-01

International audience; Three basic elements (cement, water and admixture) usually make up injectable cement grouts used for prestressed cable coating, repair and consolidation of masonry, soil grouting, etc... The present study was divided into two parts. First, in order to characterize rheologically fresh cement paste with W/C ratios (water/cement ratio) varying between 0.35 and 1, an experimental study was carried out and has revealed that the cement past behaves like a shear-thinning mate...

Utilization of cement treated recycled concrete aggregates as base or subbase layer in Egypt

Directory of Open Access Journals (Sweden)

Ahmed Ebrahim Abu El-Maaty Behiry

2013-12-01

Full Text Available Recently, environmental protection has a great concern in Egypt where recycling of increased demolition debris has become a viable option to be incorporated into roads applications. An extensive laboratory program is conducted to study the feasibility of using recycled concrete aggregate (RCA mixed with traditional limestone aggregate (LSA which is currently being used in base or subbase applications in Egypt. Moreover, the influence of mixture variables on the mechanical properties of cement treated recycled aggregate (CTRA is investigated. Models to predict the compressive and tensile strengths based on mixture parameters are established. The results show that the adding of RCA improves the mechanical properties of the mixture where the unconfined compressive strength (UCS is taken as an important quality indicator. Variables influencing the UCS such as cement content, curing time, dry density play important roles to determine the performance of CTRA.

Experimental study of cement grout : Rheological behavior and sedimentation

OpenAIRE

ROSQUOET, F; ALEXIS, A; KHELIDJ, A; PHELIPOT, A

2003-01-01

Three basic elements (cement, water and admixture) usually make up injectable cement grouts used for prestressed cable coating, repair and consolidation of masonry, soil grouting, etc. The present study was divided into two parts. First, in order to characterize rheologically fresh cement paste with water/cement ratios (W/C) varying between 0,35 and 1, an expeirmental study was carried out and has revealed that the cement past behaves like a shear-thinning material, whatever is the W/C ratio....

Behaviour of soil-cement specimens in unconfined dynamic compression

Science.gov (United States)

Davies, J.; Fendukly, L. M.

1994-06-01

The response of the cement-stabilized red marl to dynamic loading in compression has been investigated over a range of cement contents and curing times. Specimens were subjected to different stress levels below unconfined compressive strength, at a frequency of 5 Hz, and a fatigue relationship for the material was developed. The value of resilient modulus was found to be greater than the modulus of elasticity for the same cement content and curing time.

Percutaneous bone cement refixation of aseptically loose hip prostheses: the effect of interface tissue removal on injected cement volumes

Energy Technology Data Exchange (ETDEWEB)

Malan, Daniel F. [Leiden University Medical Center, Department of Orthopaedics, Leiden (Netherlands); Delft University of Technology, Department of Intelligent Systems, Delft (Netherlands); Valstar, Edward R. [Leiden University Medical Center, Department of Orthopaedics, Leiden (Netherlands); Delft University of Technology, Department of Biomechanical Engineering, Delft (Netherlands); Nelissen, Rob G.H.H. [Leiden University Medical Center, Department of Orthopaedics, Leiden (Netherlands)

2014-11-15

To quantify whether injected cement volumes differed between two groups of patients who underwent experimental minimally invasive percutaneous cement injection procedures to stabilize aseptically loose hip prostheses. One patient group was preoperatively treated using gene-directed enzyme prodrug therapy to remove fibrous interface tissue, while the other group received no preoperative treatment. It was hypothesized that cement penetration may have been inhibited by the presence of fibrous interface tissue in periprosthetic lesions. We analyzed 17 patients (14 female, 3 male, ages 72-91, ASA categories 2-4) who were treated at our institution. Osteolytic lesions and injected cement were manually delineated using 3D CT image segmentation, and the deposition of injected cement was quantified. Patients who underwent preoperative gene-directed enzyme therapy to remove fibrous tissue exhibited larger injected cement volumes than those who did not. The observed median increase in injected cement volume was 6.8 ml. Higher cement leakage volumes were also observed for this group. We conclude that prior removal of periprosthetic fibrous interface tissue may enable better cement flow and penetration. This might lead to better refixation of aseptically loosened prostheses. (orig.)

Leaching of metals from soil contaminated by mining activities.

Science.gov (United States)

Yukselen, M A; Alpaslan, B

2001-10-12

Stabilization/solidification (s/s) is one of the most effective methods of dealing with heavy metal contaminated sites. The ability of lime and cement stabilization to immobilize Pb, Cu and Fe contained in a contaminated soil originating from an old mining and smelting area located along the Mediterranean Sea shore in northern Cyprus was investigated. The stabilization was evaluated by applying leaching tests. A series of tests were conducted to optimize the additive soil ratio for the best immobilization process. Additive/soil=1/15 (m/m) ratio was found to be the optimum for both lime and cement. Application of the US EPA toxicity characteristic leaching procedure (TCLP) on the soil samples treated with lime at additive/soil=1/15 (m/m) mixing ratios showed that Cu and Fe solubility was reduced at 94 and 90%, respectively. The results of cement treatment using the same ratio, reduced the solubility 48 and 71% for Cu and Fe, respectively. The Pb solubility was found to be below the regulatory limit of 5mg/l so no additive treatment was needed. The optimum additive/soil amount (1/15) was selected for more detailed column studies, that were carried out in the acidic pH range. According to the results of column leaching tests, it was found that, the degree of heavy metal leaching is highly dependent on pH.

Subgrade stabilization alternatives to lime and cement.

Science.gov (United States)

2010-04-15

This project involved four distinct research activities, (1) the influence of temperature on lime-stabilized soils, (2) the influence of temperature on cement-stabilized soils (3) temperature modeling of stabilized subgrade and (4) use of calcium chl...

Earthworm (Eisenia andrei Avoidance of Soils Treated with Cypermethrin

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Mara M. de Andréa

2011-11-01

Full Text Available The pyrethroid insecticide cypermethrin is used for agricultural and public health campaigns. Its residues may contaminate soils and the beneficial soil organisms, like the earthworms, that may ingest the contaminated soil particles. Due to its ecological relevance, earthworms Eisenia andrei/fetida have been used in different ecotoxicological tests. The avoidance of soils treated with cypermethrin by compost worms Eisenia andrei was studied here as a bioindicator of the influence of treatment dosage and the pesticide formulation in three different agricultural soils indicated by the Brazilian environmental authorities for ecotoxicological tests. This earthworms’ behavior was studied here as a first attempt to propose the test for regulation purposes. The two-compartment test systems, where the earthworms were placed for a two-day exposure period, contained samples of untreated soil alone or together with soil treated with technical grade or wettable powder formulation of cypermethrin. After 48 h, there was no mortality, but the avoidance was clear because all earthworms were found in the untreated section of each type of soil (p < 0.05. No differences were found by the Fisher’s exact test (p ≤ 1.000 for each soil and treatment, demonstrating that the different soil characteristics, the cypermethrin concentrations and formulation, as well as the smaller amounts of soil and earthworms did not influence the avoidance behavior of the earthworms to cypermethrin. The number and range of treatments used in this study do not allow a detailed recommendation of the conditions applied here, but to the best of our knowledge, this is the first reported attempt to identify the avoidance of pesticide treated tropical soils by earthworms.

Life Cycle Assessment on Cement Treated Recycling Base (CTRB Construction

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Sudarno Sudarno

2014-08-01

Full Text Available LCA is one of the few environmental management techniques that are used to perform a risk assessment, environmental performance evaluation, environmental auditing, and environmental impact assessment and must be applied to the construction CTRB. The purpose of this study was to determine the amount of energy consumption is used and determine the amount of emissions (CO2 in the implementation of the Foundation Layer Top (base course with the former asphalt pavement aggregate blended cement / Recycling Cement Treated Base (CTRB. This study uses: (i Compilation and data inventory of relevant inputs and outputs of a product system; (ii Evaluating the potential environmental impacts associated with the data input and output; (iii Interpret the results of the inventory analysis and impact assessment in relation to the research objectives. The results showed that Energy consumption in the implementation of recycling pavement (CTRB is 225.46 MJ / km of roads and the resulting GHG emissions 17,43Ton CO2 / km of roads. Previous researchers to calculate the energy consumption of road works on the implementation of conventional (hotmix is 383.46 MJ / km of roads and the resulting GHG emissions 28.24 Ton CO2 / km of roads. If the calculated difference between a job and Hotmix CTRB and then a comparison is made CTRB energy consumption is 158 MJ / km of road, this happens 70.07% savings and GHG emissions resulting difference is 10.81 tons of CO2 / km of road, resulting in a decrease in 62,02%.

Physical and mechanical properties of sand stabilized by cement and natural zeolite

Science.gov (United States)

Salamatpoor, Sina; Jafarian, Yaser; Hajiannia, Alborz

2018-05-01

Loose sands are prone to lose their shear strength when being subjected to static or cyclic loads. To this end, there exist several methods to improve the mechanical properties of sands, but the most crucial and viable approach is the one with the lowest harmful environmental impact both in production and recycling processes. In this regard, zeolite as a natural pozzolanic additive offers an eco-friendly improvement in strength parameters of cemented sandy soils. Thereby, in this study, a series of unconfined compressive strength (UCS) tests are conducted to evaluate the mechanical parameters of the zeolite-cemented sand. The results demonstrate a meaningful increase in the UCS of the treated sand samples for replacement of cement by zeolite at an optimum proportion of 40% in specimens with 14 and 28 days curing time. The effectiveness of the improvement process is demonstrated by the strength improvement ratio which was up to be 128% to 209% for the samples with 14 and 28 days curing time, respectively. With regard to the above results, zeolite can be introduced as a promising cement substitute in stabilization of sandy ground including backfills, roadbed, embankments, and other structural filling systems.

Prediction of zeolite-cement-sand unconfined compressive strength using polynomial neural network

Science.gov (United States)

MolaAbasi, H.; Shooshpasha, I.

2016-04-01

The improvement of local soils with cement and zeolite can provide great benefits, including strengthening slopes in slope stability problems, stabilizing problematic soils and preventing soil liquefaction. Recently, dosage methodologies are being developed for improved soils based on a rational criterion as it exists in concrete technology. There are numerous earlier studies showing the possibility of relating Unconfined Compressive Strength (UCS) and Cemented sand (CS) parameters (voids/cement ratio) as a power function fits. Taking into account the fact that the existing equations are incapable of estimating UCS for zeolite cemented sand mixture (ZCS) well, artificial intelligence methods are used for forecasting them. Polynomial-type neural network is applied to estimate the UCS from more simply determined index properties such as zeolite and cement content, porosity as well as curing time. In order to assess the merits of the proposed approach, a total number of 216 unconfined compressive tests have been done. A comparison is carried out between the experimentally measured UCS with the predictions in order to evaluate the performance of the current method. The results demonstrate that generalized polynomial-type neural network has a great ability for prediction of the UCS. At the end sensitivity analysis of the polynomial model is applied to study the influence of input parameters on model output. The sensitivity analysis reveals that cement and zeolite content have significant influence on predicting UCS.

Field and lab evaluation of the use of lime fly ash to replace soil cement as a base course : technical summary.

Science.gov (United States)

1997-09-01

The purpose of this project was to design and construct lime/fly ash stabilized base course test sections which would be economical compared to a soil cement stabilized base, utilize a recyclable material, and possibly reduce shrinkage cracking on ba...

Acidic Attack Resistance of Cement Mortar Treated with Alkaline

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Nadia Nazhat Sabeeh

2017-12-01

Full Text Available The negative effect of acidic attack on the properties of concrete and cement mortar is a topic of increasing significance in the recent years. Many attempts has occurred to mitigate this negative impact by improving the properties of concrete and increase resistance to acids by using additives. The present study includes treatment of sand by alkaline material and examine the effect of treatment on cement mortar resistance towards hydrochloric and sulfuric acid. Results show that sand treatment by alkaline material significantly enhance mortar ability to resist acids. In terms of loss weight, the maximum weight rate gain was 25.54% for specimens immersed in Hydrochloric acid with water cement ratio 40%. For specimens immersed in HCl, the average gain in compressive strength is (20.15-19.433% for w/c (40-45% respectively. The average gain in modulus of rupture toward the influence of H2SO4 is (18.37–17.99% for w/c (40-45%, respectively.

Leaching of arsenic, copper and chromium from thermally treated soil.

Science.gov (United States)

Kumpiene, Jurate; Nordmark, Désirée; Hamberg, Roger; Carabante, Ivan; Simanavičienė, Rūta; Aksamitauskas, Vladislovas Česlovas

2016-12-01

Thermal treatment, if properly performed, is an effective way of destroying organic compounds in contaminated soil, while impact on co-present inorganic contaminants varies depending on the element. Leaching of trace elements in thermally treated soil can be altered by co-combusting different types of materials. This study aimed at assessing changes in mobility of As, Cr and Cu in thermally treated soil as affected by addition of industrial by-products prior to soil combustion. Contaminated soil was mixed with either waste of gypsum boards, a steel processing residue (Fe 3 O 4 ), fly ash from wood and coal combustion or a steel abrasive (96.5% Fe 0 ). The mixes and unamended soil were thermally treated at 800 °C and divided into a fine fraction 0.125 mm to simulate particle separation occurring in thermal treatment plants. The impact of the treatment on element behaviour was assessed by a batch leaching test, X-ray absorption spectroscopy and dispersive X-ray spectrometry. The results suggest that thermal treatment is highly unfavourable for As contaminated soils as it increased both the As leaching in the fine particle size fraction and the mass of the fines (up to 92%). Soil amendment with Fe-containing compounds prior to the thermal treatment reduced As leaching to the levels acceptable for hazardous waste landfills, but only in the coarse fraction, which does not justify the usefulness of such treatment. Among the amendments used, gypsum most effectively reduced leaching of Cr and Cu in thermally treated soil and could be recommended for soils that do not contain As. Fly ash was the least effective amendment as it increased leaching of both Cr and As in majority of samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

prediction of flexural strength of chikoko pozzolana blended cement

African Journals Online (AJOL)

user

optimize the flexural strength of chikoko pozzolana blended cement concrete using Osadebe's regression function. The ... such as cement [1-3]. Nigeria is blessed with abundance of local building and construction materials such as stones, sand, laterite and timber. However ...... Soil Stabilization”, International Journal of.

Biodegradability of pharmaceutical compounds in agricultural soils irrigated with treated wastewater

International Nuclear Information System (INIS)

Grossberger, Amnon; Hadar, Yitzhak; Borch, Thomas; Chefetz, Benny

2014-01-01

Pharmaceutical compounds (PCs) are introduced into agricultural soils via irrigation with treated wastewater (TWW). Our data show that carbamazepine, lamotrigine, caffeine, metoprolol, sulfamethoxazole and sildenafil are persistent in soils when introduced via TWW. However, other PCs, namely diclofenac, ibuprofen, bezafibrate, gemfibrozil and naproxen were not detected in soils when introduced via TWW. This is likely due to rapid degradation as confirmed in our microcosm studies where they exhibited half-lives (t 1/2 ) between 0.2–9.5 days when soils were spiked at 50 ng/g soil and between 3 and 68 days when soils were spiked at 5000 ng/g soil. The degradation rate and extent of PCs observed in microcosm studies were similar in soils that had been previously irrigated with TWW or fresh water. This suggests that pre-exposure of the soils to PCs via irrigation with TWW does not enhance their biodegradation. This suggests that PCs are probably degraded in soils via co-metabolism. Highlights: • Some pharmaceuticals are highly persistent in arable soils. • Weak acid pharmaceuticals are readily degradable in agricultural soils. • Irrigation with treated wastewater does not enhance degradation of pharmaceuticals. • Degradation of pharmaceuticals in soil is probably occurred via co-metabolism. -- Some pharmaceutical compounds are persistent in arable soils when introduced via irrigation with treated wastewater

Tympanoplasty with ionomeric cement

DEFF Research Database (Denmark)

Kjeldsen, A D; Grøntved, A M

2000-01-01

with isolated erosion of the long incus process have been treated with a new surgical technique in which the ossicular chain was rebuilt with ionomeric cement. The results in hearing performance (mean pure-tone average (PTA) 0.5, 1 and 2 kHz) were evaluated pre- and post-surgery, and compared to those...... of > 10 dB, in 4 there was a slight improvement and in 2 a decline. The difference was not statistically significant. Hearing improvement using ionomeric cement in type II tympanoplasty was satisfactory. Reconstruction of the ossicular chain with ionomeric cement is recommended, as the procedure is easy...

Influence of Portland Cement Class on the Corrosion Rate of Steel Reinforcement in Cement Mortar Caused by Penetrating Chloride and Sulfate from the Environment

Directory of Open Access Journals (Sweden)

Bikić, F.

2013-01-01

Full Text Available The influence of portland cement class on the corrosion rate of steel reinforcement in cement mortar caused by penetrating chloride or sulfate from the environment in already hardened cement mortar is investigated in this paper. Three classes of portland cement have been used for the tests, PC 35, PC 45 and PC 55. Cylindrical samples of cement mortar with steel reinfor- cement in the middle were treated 6 months at room temperature in the following solutions: w(SO42- = 2.1 % and w(Cl- = 5 %. Two techniques have been used for testing corrosion rate of steel reinforcement in cement mortar: Tafel extrapolation technique and potentiodynamic polarization technique. Investigations were conducted by potentiostat/galvanostat Princeton Applied Research 263A-2 with the software PowerCORR®. The results of both techniques indi-cate the most active corrosion of steel reinforcement in the samples prepared from cement PC 35 in both treated solutions, while the lowest corrosion of the steel reinforcement was observed in cement samples prepared from cement PC 55. This conclusion was drawn by analyzing the results shown in Figs. 1–4. Comparing corrosion current density of samples, working electrodes, Figs. 1 and 2, Table 2, the results show the most stable corrosion of steel reinforcement in samples prepared from cement PC 55, and the most active corrosion in samples prepared from ce- ment PC 35. The most active corrosion in samples prepared from cement PC 35 is evident from the positions of the open circuit potentials whose values are less for samples prepared from cement PC 35 in both the treated solution, Figs. 1 and 2, Table 2. Comparison of the anodic polarization curves of the working electrodes in both the treated solutions, Figs. 3 and 4, also shows that the intensity of corrosion is the largest for the working electrodes prepared from cement PC 35 and the smallest for the working electrodes prepared from cement PC 55. Investigation results should be

IPS Empress onlays luted with two dual-cured resin cements for endodontically treated teeth: a 3-year clinical evaluation.

Science.gov (United States)

Atali, Pinar Yilmaz; Cakmakcioglu, Ozcan; Topbasi, Bulent; Turkmen, Cafer; Suslen, Ozlem

2011-01-01

The aim of this study was to evaluate the performance of IPS Empress ceramic onlays luted with two dual-cured adhesive resin cements for endodontically treated teeth. Twenty molar teeth were restored with all-ceramic restorations luted randomly with Maxcem or Clearfil Esthetic Cement and DC Bond Kit luting systems (n = 10 each) in 20 patients. The restorations were assessed using modified US Public Health Service criteria at baseline, 6 months, and 1, 2, and 3 years. A statistically significant deterioration was found for the criteria marginal integrity, anatomical form, and surface roughness. For luting of ceramic onlays, no difference between the two luting systems was detected.

Some geotechnical properties of a cement-stabilized granite-gneiss ...

African Journals Online (AJOL)

This was with a view to determining the influence of cement on some engineering properties of the soil. ... the maximum Dry Density and the percentage cement of the samples compacted at the West African and Modified American Association of State Highways and Transportation Officials (AASHTO) levels respectively.

Clay-cement suspensions - rheological and functional properties

Science.gov (United States)

Wojcik, L.; Izak, P.; Mastalska-Poplawska, J.; Gajek, M.

2017-01-01

The piping erosion in soil is highly unexpected in civil engineering. Elimination of such damages is difficult, expensive and time-consuming. One of the possibility is the grouting method. This method is still developed into direction of process automation as well as other useful properties of suspensions. Main way of modernization of the grouting method is connected it with rheology of injection and eventuality of fitting them to specific problems conditions. Very popular and useful became binders based on modified clays (clay-cement suspensions). Important principle of efficiency of the grouting method is using of time-dependent pseudothixotropic properties of the clay-cement suspensions. The pseudo-rheounstability aspect of the suspensions properties should be dedicated and fitted to dynamic changes of soil conditions destructions. Whole process of the modification of the suspension rheology is stimulated by the specific agents. This article contains a description of practical aspects of the rheological parameters managing of the clay-cement suspensions, dedicated to the building damages, hydrotechnic constructions etc.

Gamma Spectrometry Analysis of Different Brands of Cement used in Nigeria

International Nuclear Information System (INIS)

Olarinoye, I.O.; Baba-Kutigi, A.N.; Sharifat, I.; Kolo, M.T.

2014-01-01

The natural radionuclide content of common brands of cement consumed in Nigeria is presented in this work. Samples of 9 brands of grey ordinary Portland cement (OPC) and 5 brands of white cement were collected and analyzed for their radiological content by gamma spectrometry using a 7.6 x 7.6 NaI(TI) detector. The total average content of 226 Ra, 232 Th and 40 k for all the cement brand samples were 38.1, 27.9 and 301.1 Bq/kg respectively and are lower when compared to the world average (50, 50 and 500 Bq/Kg) in building materials. The evaluated radium equivalent activities, external and internal indices were lower than the recommended safe limit and are comparable with result from similar studies concluded in other countries. The evaluation mean gonadal dose of equivalents of two cement brand samples were found to be higher than the world average in soil while others are less than the world average in soil.

UNSTABLE INTERTROCHANTERIC FRACTURE IN ELDERLY TREATED WITH CEMENTED BIPOLAR HEMIARTHROPLASTY AND TROCHANTERIC RECONSTRUCTION

Directory of Open Access Journals (Sweden)

Jagadeesh Kumar

2015-06-01

Full Text Available INTRODUCTION : Unstable inter - trochanteric fracture in the geriatric population is a common injury and is associated with poor bone quality, excessive collapse, loss of fixation, and cut - out of the lag screw, are the common problems of attempts to fix these fractures. Pr esent study is an attempt to evaluate the functional outcome of primary cemented bipolar hemiarthroplasty and trochanter reconstruction in these patients. MATERIALS AND METHOD S : This prospective study included 30 cases of elderly osteoporotic patients with mean age of 65.4 years who sustained comminuted inter - trochanteric femur fracture treated with cemented bipolar hemiarthroplasty& tension band wiring for greater trochanter rec onstruction. It is an essential technical step to avoid complication like abductor lurch gait. W e here describe a technique of reconstruction and fixation of greater trochanter using tension band wiring in figure of eight pattern. The patients were followe d up at six week, three month, six month and one year postoperatively and assessed using Harris Hip Score (HHS. RESULTS : The mean HHS score was was 85.6+SD 9.5 (range from 74 to 96. B y the end of one year. The main clinical measures were early post - opera tive full weight bearing, post - operative complication & functional outcome. The time to full weight bearing, the rate of post - operative complications & functional outcome was significantly better in cemented bipolar arthroplasty group . DISCUSSION : The chan ges in HHS up to six months periods are much greater which starts showing a stable trend thereafter. Fair to good scores were observed in all the patients. The purpose of its use was that while Harris Hip Score (HHS provides information on a multitude of factors. Superficial infection in 2 patients, anterior thigh pain in a patient, shortening less than 2cms in 2 patients, abductor lurch in a patient are the complications noted in post - operative period, but no patient required

Importance of microscopy in durability studies of solidified and stabilized contaminated soils

Science.gov (United States)

Klich, I.; Wilding, L.P.; Drees, L.R.; Landa, E.R.

1999-01-01

Solidification/stabilization (S/S) is recognized by the U.S. EPA as a best demonstrated available technology for the containment of contaminated soils and other hazardous wastes that cannot be destroyed by chemical, thermal, or biological means. Despite the increased use of S/S technologies, little research has been conducted on the weathering and degradation of solidified and stabilized wastes once the treated materials have been buried. Published data to verify the performance and durability of landfilled treated wastes over time are rare. In this preliminary study, optical and electron microscopy (scanning electron microscopy [SEM], transmission electron microscopy [TEM] and electron probe microanalyses [EPMA]) were used to evaluate weathering features associated with metal-bearing contaminated soil that had been solidified and stabilized with Portland cement and subsequently buried on site, stored outdoors aboveground, or achieved in a laboratory warehouse for up to 6 yr. Physical and chemical alteration processes identified include: freeze-thaw cracking, cracking caused by the formation of expansive minerals such as ettringite, carbonation, and the movement of metals from waste aggregates into the cement micromass. Although the extent of degradation after 6 yr is considered slight to moderate, results of this study show that the same environmental concerns that affect the durability of concrete must be considered when evaluating the durability and permanence of the solidification and stabilization of contaminated soils with cement. In addition, such evaluations cannot be based on leaching and chemical analyses alone. The use of all levels of microscopic analyses must be incorporated into studies of the long-term performance of S/S technologies.Solidification/stabilization (S/S) is recognized by the U.S. EPA as a best demonstrated available technology for the containment of contaminated soils and other hazardous wastes that cannot be destroyed by chemical

Mycostimulation in a glyphosate treated arable soil: implications on ...

African Journals Online (AJOL)

Mycostimulation in a glyphosate treated arable soil: implications on the yield and agronomic characters of Talinum fruticosum (L.) Juss. ... If properly managed and stimulated, fungi can contribute significantly to improving soil health, thus improving food security in a sustainable manner. Keywords: Mycoaugmentation ...

Impact of lime treated soils performance on design of earthfill dikes

Directory of Open Access Journals (Sweden)

Nerincx Nicolas

2016-01-01

Full Text Available Nowadays soil treatment with lime in civil engineering is widespread in many countries on all continents, within several construction fields. The interest of the hydraulic works community regarding this technique is currently growing. It has been indeed shown during the last decade that appropriate treatment technologies provide lime treated soils with high level properties such as excellent homogeneity, low permeability, internal and external erosion resistance and mechanical stability. Those have been shown in laboratory and for some properties with full scale experiments. The so conferred soil properties can lead to innovative earthfill dams and dikes designs by addressing some of the typical designer’s problems, such as stability, watertightness, internal erosion, surface protection and flood control. However, lime treated soil external erosion resistance is still to be quantified in the field for proper designing and dimensioning of lime treated soil external erosion protection or spillways. With this purpose, an experimental earthfill dike has been built along the river Vidourle (France in July 2015, in the frame of the French R&D program “DigueELITE”. This 50 m long and 3,5 m high dike is made of lime treated silt and is provided with sensors (succion, water content and temperature and piezometer in order to be monitored. It will also be tested against surface erosion. The final objective of this R&D program is to provide guidelines for designing innovative overflow resistant earthfill dikes. This article describes the performance reached by lime treated soils and associated design requirements and application; the experimental dike construction and lessons learned; the monitoring program; the dike design perspectives opened by soil treatment.

Strength and Stiffness Development in Soft Soils: A FESEM aided Soil Microstructure Viewpoint

Science.gov (United States)

Wijeyesekera, D. C.; Ho, M. H.; Bai, X.; Bakar, I.

2016-07-01

This paper opens with an overview of the debatable definition of soft soil that goes beyond a (CH) organic / inorganic clay and OH peat to include weakly cemented periglacial deposits of loess and alike. It then outlines the findings obtained from stiffness test on cement-stabilised soft clay. The findings are complemented with a microstructure viewpoint obtained using field emission scanning electron microscope (FESEM). Research also comprised of making cylindrical stabilised clay samples, prepared in the laboratory with various rubber chips contents and cement, and then aged for 28 days. The samples were then subjected to unconfined compressive strength (UCS) test and observations were also made of its microstructure using the FESEM. The impact of the soil microstructure on the stiffness result was studied both with the stabilized soil and also of some of the natural undisturbed loess soils. Sustainability aspect and the potential of the use of rubber chips and sand as additives to cement stabilisation are also discussed. The overall test results indicated that rubber chips and sand contributed to the improvement in unconfined compressive strength (qu). The derogatory influence of moisture on the stiffness of the stabilised clay was studied simultaneously. SEM micrographs are presented that show bonding of cement, rubber chips/ sand and soft clay, granular units and aggregated / agglomerated units in loess. The paper concludes with observations on the dependence of soil microstructure on the soil strength and deformability and even collapsibility of the loess. Current practices adopted as engineering solutions to these challenging soils are outlined.

An innovative method for the solidification/stabilization of PAHs-contaminated soil using sulfonated oil.

Science.gov (United States)

Ma, Fujun; Wu, Bin; Zhang, Qian; Cui, Deshan; Liu, Qingbing; Peng, Changsheng; Li, Fasheng; Gu, Qingbao

2018-02-15

Stabilization/solidification (S/S) has been successfully employed in many superfund sites contaminated with organic materials. However, this method's long-term effectiveness has not been fully evaluated and the increase in soil volume following treatment is unfavorable to follow-up disposal. The present study developed a novel method for the S/S of PAHs-contaminated soil with the facilitation of sulfonated oil (SO). Adding SO significantly improved the unconfined compressive strength (UCS) values of Portland cement and activated carbon (PC-AC) treated soil samples, and the UCS values of the soil sample treated with 0.02% of SO were up to 2.3 times higher than without SO addition. When the soil was treated with PC-AC-SO, the PAHs leaching concentrations were 14%-25% of that in leachates of the control soil, and high molecular weight PAHs including benzo(a)pyrene were rarely leached. Freeze/thaw durability tests reveal that the leachability of PAHs was not influenced by freeze-thaw cycles. The UCS values of PC-AC-SO treated soil samples were 2.2-3.4 times greater than those of PC-AC treated soil samples after 12 freeze-thaw cycles. The PC-AC-SO treated soils resist disintegration better when compared to the PC-AC treated soils. The SEM micrographs reveal that the soils' compactness was significantly improved when treated with SO. Copyright © 2017 Elsevier B.V. All rights reserved.

Soil Chemistry after Irrigation with Treated Wastewater in Semiarid Climate

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Pedro Carlos Pacheco de Oliveira

2016-01-01

Full Text Available ABSTRACT Soil irrigation using treated wastewater in the Brazilian semiarid region is a promising practice as this area currently faces water scarcity and pollution of water resources by domestic sewage. The aim of this study was to evaluate the use of treated wastewater in drip irrigation and its effect on the chemistry of soil cultivated with squash (Cucurbita maxima Duch. Coroa IAC and to verify whether there was an increase in soil salinity under a semiarid climate. The experiment was conducted for 123 days on a farm close to the sewage treatment plant, in a randomized block design with five treatments and four replications. The treatments consisted of two irrigation water depths (100 and 150 % of the evapotranspiration, two applications of gypsum to attenuate wastewater sodicity (0 and 5.51 g per plant, and a control treatment with no application of wastewater or gypsum. During the experiment, treated wastewater and soil gravitational water, at a depth of 0.40 m, were collected for measurement of Na+, K+, Ca2+, Mg2+, NO−3, NH4+, Cl− , alkalinity, electrical conductivity, pH and sodium adsorption ratio. At the end of the experiment, soil samples were collected at depths of 0.00-0.10, 0.10-0.20, and 0.20-0.40 m; and pH, total N, organic C, exchangeable cations and electrical conductivity of the saturation extract (CEs were analyzed. Besides an increase in pH and a reduction in total N, the irrigation with wastewater reduces soil salinity of the naturally salt-rich soils of the semiarid climate. It also led to soil sodification, in spite of the added gypsum, which indicates that irrigation with wastewater might require the addition of greater quantities of gypsum to prevent physical degradation of the soil.

Recovery of MSWI and soil washing residues as concrete aggregates.

Science.gov (United States)

Sorlini, Sabrina; Abbà, Alessandro; Collivignarelli, Carlo

2011-02-01

The aim of the present work was to study if municipal solid waste incinerator (MSWI) residues and aggregates derived from contaminated soil washing could be used as alternative aggregates for concrete production. Initially, chemical, physical and geometric characteristics (according to UNI EN 12620) of municipal solid waste incineration bottom ashes and some contaminated soils were evaluated; moreover, the pollutants release was evaluated by means of leaching tests. The results showed that the reuse of pre-treated MSWI bottom ash and washed soil is possible, either from technical or environmental point of view, while it is not possible for the raw wastes. Then, the natural aggregate was partially and totally replaced with these recycled aggregates for the production of concrete mixtures that were characterized by conventional mechanical and leaching tests. Good results were obtained using the same dosage of a high resistance cement (42.5R calcareous Portland cement instead of 32.5R); the concrete mixture containing 400 kg/m(3) of washed bottom ash and high resistance cement was classified as structural concrete (C25/30 class). Regarding the pollutants leaching, all concrete mixtures respected the limit values according to the Italian regulation. Copyright © 2010 Elsevier Ltd. All rights reserved.

Proposal of a sequential treatment methodology for the safe reuse of oil sludge-contaminated soil.

Science.gov (United States)

Mater, L; Sperb, R M; Madureira, L A S; Rosin, A P; Correa, A X R; Radetski, C M

2006-08-25

In this study sequential steps were used to treat and immobilize oil constituents of an oil sludge-contaminated soil. Initially, the contaminated soil was oxidized by a Fenton type reaction (13 wt% for H(2)O(2); 10mM for Fe(2+)). The oxidative treatment period of 80 h was carried out under three different pH conditions: 20 h at pH 6.5, 20 h at pH 4.5, and 40 h at pH 3.0. The oxidized contaminated sample (3 kg) was stabilized and solidified for 2h with clay (1 kg) and lime (2 kg). Finally, this mixture was solidified by sand (2 kg) and Portland cement (4 kg). In order to evaluate the efficiency of different processes to treat and immobilize oil contaminants of the oil sludge-contaminated soil, leachability and solubility tests were performed and extracts were analyzed according to the current Brazilian waste regulations. Results showed that the Fenton oxidative process was partially efficient in degrading the oil contaminants in the soil, since residual concentrations were found for the PAH and BTEX compounds. Leachability tests showed that clay-lime stabilization/solidification followed by Portland cement stabilization/solidification was efficient in immobilizing the recalcitrant and hazardous constituents of the contaminated soil. These two steps stabilization/solidification processes are necessary to enhance environmental protection (minimal leachability) and to render final product economically profitable. The treated waste is safe enough to be used on environmental applications, like roadbeds blocks.

Waste conditioning technology of radiocontaminated soil

International Nuclear Information System (INIS)

Chen Dahua; Wang Xiaoli; Chen Xin

2012-01-01

A special conditioning way for low level soil contaminated by 241 Am was discussed. Firstly, the contaminated soil was condensed in package container (200 L drum) by 20 t pressing machine. The contaminated soil was pressed from loose state to compaction state, and the volume reduction rate was from 1.1 to 1.4. Secondly, cement with thickness of 10 cm to 15 cm was poured on the package container for sealing. Thus, a cement sealing member was made up by contaminated soil and it could be described as normal solid waste. Finally, taking the cement sealing member as conditioning object, using Ⅶ steel trunk as package container and cement conditioning, Ⅶ steel trunk package was got. Through radiation monitoring, the Ⅶ steel trunk package can satisfy the transport requirement of radiation waste. Also, it can satisfy the accept and disposal requirements of national repository. (authors)

Radon exhalation study in cements and other building materials

International Nuclear Information System (INIS)

Singh, J.; Sharma, N.

2012-01-01

Radon is a radioactive inert gas, which is produced during the decay of radium, an element present in the naturally occurring uranium series. In the recent past, environmental scientists all over the world have been expressing great concern about the radiation hazard from radon and its short lived daughter products inside buildings. The radon concentration inside a building depends upon the radon exhalation from the building materials used for the construction and the soil underneath the building. In the present investigations, a comparative study for radon exhalation rate has been carried out in some Indian and Pakistani cements and other building materials being used locally such as sand, soil, bricks, marbles, CaCO 3 , POPs by using Track Etch Technique. The Pakistani cement with the trade name 'Elephant' shows the minimum mass exhalation rate while the Indian 'Birla White' cement has shown the maximum. Among the other building materials studied, CaCO 3 has shown the minimum, while local soil the maximum mass exhalation rate. Out of the fired clay bricks, roof tiles, floor tiles and different marbles, floor tiles have the minimum areal exhalation rate while roof tiles the maximum. (author)

Effect of Treated Wastewater Irrigation on Heavy Metals Distribution in a Tunisian Soil

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K. Khaskhoussy

2015-06-01

Full Text Available Treated wastewater (TWW may contain toxic chemical constituents that pose negative environmental and health impacts. In this study, soil samples under treated wastewater irrigation were studied. For this purpose, six plots were made in an irrigated area in north of Tunisia and treated with two water qualities: fresh water (FW and treated wastewater (TWW. Five soil depths were used: 0-30, 30-60, 60-90, 90-120 and 120-150 cm. The TWW irrigation increased significantly (P≤0.05 the soils’ EC, Na, K, Ca, Mg, Cl, SAR, Cu, Cd and Ni and had no significant (P ≤0.05 effect on the soils’ pH, Zn, Co and Pb contents. EC, Na, Cl, SAR, Zn and Co increased significantly with soil depth. The results for K, Ca, Mg, Cd, Pb and Ni exhibited similar repartition in different layers of soil. It was also shown that the amount of different elements in soil irrigated with fresh water (FW were less compared with the control soil

The design and performance of a low-cost, soil cement cap for LLNW disposal trenches

International Nuclear Information System (INIS)

Nowatzki, E.A.

1986-01-01

Over the past three years, the University of Arizona has conducted research for the U.S. Nuclear Regulatory Commission (USNRC) to assess various trench cap designs from the viewpoint of structural stability, water infiltration, and economy. As part of that project, four experimental trenches were built and monitored at each of two semi-arid sites in the vicinity of Tucson, Arizona. In this paper, the design and construction of one of those trenches are described in detail. That trench included a cap-crown system that incorporates compacted soil backfill and a steel-reinforced, soil-cement cap with an overlying 'wick' drain. The results of structural monitoring over a period of approximately 2 years are presented and compared to those of a more conventionally designed trench. The results are evaluated with respect to surface subsidence and movements of the cap-crown components as they affect moisture infiltration. Recommendations are made regarding standard design criteria for LLNW disposal trenches based on the results of this research

CEMENT SLURRIES FOR GEOTHERMAL WELLS CEMENTING

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Nediljka Gaurina-Međimurec

1994-12-01

Full Text Available During a well cementing special place belongs to the cement slurry design. To ensure the best quality of cementing, a thorough understanding of well parameters is essential, as well as behaviour of cement slurry (especially at high temperatures and application of proven cementing techniques. Many cement jobs fail because of bad job planning. Well cementing without regarding what should be accomplished, can lead to well problems (channels in the cement, unwanted water, gas or fluid production, pipe corrosion and expensive well repairs. Cementing temperature conditions are important because bot-tomhole circulating temperatures affect slurry thickening time, arheology, set time and compressive strength development. Knowing the actual temperature which cement encounters during placement allows the selection of proper cementing materials for a specific application. Slurry design is affected by well depth, bottom hole circulating temperature and static temperature, type or drilling fluid, slurry density, pumping time, quality of mix water, fluid loss control, flow regime, settling and free water, quality of cement, dry or liquid additives, strength development, and quality of the lab cement testing and equipment. Most Portland cements and Class J cement have shown suitable performances in geot-hermal wells. Cement system designs for geothermal wells differ from those for conventional high temperature oil and gas wells in the exclusive use of silica flour instead of silica sand, and the avoidance of fly ash as an extender. In this paper, Portland cement behaviour at high temperatures is described. Cement slurry and set cement properties are also described. Published in literature, the composition of cement slurries which were tested in geothermal conditions and which obtained required compressive strength and water permeability are listed. As a case of our practice geothermal wells Velika Ciglena-1 and Velika Ciglena-la are described.

Portland cement versus MTA as a root-end filling material. A pilot study.

Science.gov (United States)

da Silva, Sérgio Ribeiro; da Silva Neto, José Dias; Veiga, Daniela Francescato; Schnaider, Taylor Brandão; Ferreira, Lydia Masako

2015-02-01

To assess periradicular lesions clinically and by computed tomography (CT) after endodontic surgery using either Portland cement or mineral trioxide aggregate (MTA) as a root-end filling material. Three patients diagnosed with periradicular lesions by cone-beam CT underwent endodontic surgery with root-end filling. Patient A was treated with MTA as the root-end filling material, patient B was treated with Portland cement and patient C had two teeth treated, one with MTA and the other with Portland cement. Six months after surgery, the patients were assessed clinically and by CT scan and the obtained results were compared. Periradicular tissue regeneration was observed in all cases, with no significant differences in bone formation when comparing the use of MTA and Portland cement as root-end filling materials. Both mineral trioxide aggregate and Portland cement were successful in the treatment of periradicular lesions.

VUJE experience with cementation of liquid and wet radioactive waste

International Nuclear Information System (INIS)

Kravarik, Kamil; Holicka, Zuzana; Pekar, Anton; Zatkulak, Milan

2011-01-01

Liquid and wet LLW generated during operation as well as decommissioning of NPPs is treated with different methods and fixed in a suitable fixation matrix so that a final product meets required criteria for its disposal in a final repository. Cementation is an important process used for fixation of liquid and wet radioactive waste such as concentrate, spent resins and sludge. Active cement grout is also used for fixation of low level solid radioactive waste loaded in final packing containers. VUJE Inc. has been engaged in research of cementation for long. The laboratory for analyzing radioactive waste properties, prescription of cementation formulation and estimation of final cement product properties has been established. Experimental, semi-production cementation plant has been built to optimize operation parameters of cementation. VUJE experience with cementation of liquid and wet LLW is described in the presented paper. VUJE has assisted in commissioning of Jaslovske Bohunice Treatment Centre. Cement formulations for treatment of concentrate, spent resins and sludge have been developed. Research studies on the stability of a final concrete packaging container for disposal in repository have been performed. Gained experience has been further utilized for design and manufacture of several cementation plants for treatment of various liquid and wet LLW. Their main technological and technical parameters as well as characterization of treated waste are described in the paper. Applications include the Mochovce Final Treatment Centre, Movable Cementation Facility utilizing in-drum mixing for treatment of sludge, Cementation Facility for treatment of tritiated water in Latvia and Cementation Facility for fixation of liquid and solid institutional radioactive waste in Bulgaria, which utilizes lost stirrer mixer. (author)

Outcomes of osteoporotic trochanteric fractures treated with cement-augmented dynamic hip screw

Science.gov (United States)

Gupta, Rakesh Kumar; Gupta, Vinay; Gupta, Navdeep

2012-01-01

Background: Dynamic hip screw (DHS) has been the standard treatment for stable trochanteric fracture patterns, but complications of lag screw cut out from a superior aspect, due to inadequate bone anchorage, occur frequently in elderly osteoporotic patients. Polymethylmethacrylate (PMMA) has been used as an augmentation tool to facilitate fixation stability in cadaveric femora for biomechanical studies and in pathological fractures. However, there are very few reports on the utilization of PMMA cement to prevent these complications in fresh intertrochanteric fractures. A prospective study was conducted to evaluate the outcome and efficacy of PMMA augmented DHS in elderly osteoporotic patients with intertrochanteric fractures. Materials and Methods: The study included 64 patients (AO type31-A2.1 in eight, A2.2 in 29, A2.3 in 17 patients, and 31-A3.1 in five, A3.2 in three, and A3.3 in two patients) with an average age of 72 years (60 – 94 years) of which 60 were available for final followup. PMMA augmentation of DHS was performed in all cases by injecting PMMA cement into the femoral head with a custommade gun designed by the authors. The clinical outcome was rated as per the Salvati and Wilson scoring system at the time of final followup of one year. Results were graded as excellent (score > 31), good (score 24 – 31), fair (score 16 – 23), and poor (score < 16). Results: Fracture united in all patients and the average time to union was 13.8 weeks (range 12 – 16 weeks). At an average followup of 18 months (range 12 – 24 months), no incidence of varus collapse or superior screw cut out was observed in any of the patients in spite of weightbearing ambulation from the early postoperative period. There was no incidence of avascular necrosis (AVN) or cement penetration into the joint in our series. Most of the patients were able to regain their prefracture mobility status with a mean hip pain score of 8.6. Conclusion: Cement augmentation of DHS appears to be an

Outcomes of osteoporotic trochanteric fractures treated with cement-augmented dynamic hip screw

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Rakesh Kumar Gupta

2012-01-01

Full Text Available Background: Dynamic hip screw (DHS has been the standard treatment for stable trochanteric fracture patterns, but complications of lag screw cut out from a superior aspect, due to inadequate bone anchorage, occur frequently in elderly osteoporotic patients. Polymethylmethacrylate (PMMA has been used as an augmentation tool to facilitate fixation stability in cadaveric femora for biomechanical studies and in pathological fractures. However, there are very few reports on the utilization of PMMA cement to prevent these complications in fresh intertrochanteric fractures. A prospective study was conducted to evaluate the outcome and efficacy of PMMA augmented DHS in elderly osteoporotic patients with intertrochanteric fractures. Materials and Methods: The study included 64 patients (AO type31-A2.1 in eight, A2.2 in 29, A2.3 in 17 patients, and 31-A3.1 in five, A3.2 in three, and A3.3 in two patients with an average age of 72 years (60 − 94 years of which 60 were available for final followup. PMMA augmentation of DHS was performed in all cases by injecting PMMA cement into the femoral head with a custommade gun designed by the authors. The clinical outcome was rated as per the Salvati and Wilson scoring system at the time of final followup of one year. Results were graded as excellent (score > 31, good (score 24 − 31, fair (score 16 − 23, and poor (score < 16. Results: Fracture united in all patients and the average time to union was 13.8 weeks (range 12 − 16 weeks. At an average followup of 18 months (range 12 − 24 months, no incidence of varus collapse or superior screw cut out was observed in any of the patients in spite of weightbearing ambulation from the early postoperative period. There was no incidence of avascular necrosis (AVN or cement penetration into the joint in our series. Most of the patients were able to regain their prefracture mobility status with a mean hip pain score of 8.6. Conclusion: Cement augmentation of DHS appears

Fluid sign in the treated bodies after percutaneous vertebroplasty

International Nuclear Information System (INIS)

Lin, Chao-Chun; Yen, Pao-Sheng; Wen, Shu-Hui

2008-01-01

The aims of this study are to describe non-healing in the treated vertebral body after percutaneous vertebroplasty and analyze the influence of vacuum cleft, location, and severity of collapse on the development of nonunion cement. Of 208 patients (266 treated vertebral bodies) who were treated with percutaneous vertebroplasty from September 2002 to May 2006, 23 patients (41 treated levels) with residual or recurrent pain underwent follow-up magnetic resonance imaging (MRI) study. Retrospective chart review with analysis of preoperative and postoperative MRIs were performed in these 23 patients. In the 41 treated vertebral bodies, 22 of 41 bodies had vacuum cleft found in the preoperative MRI study. Eight of the 22 treated vertebral bodies with preoperative vacuum clefts were found to have fluid between the interface of cement and the residual bone in the collapsed vertebral bodies on follow-up MRI. The adjacent discs of these treated vertebral bodies were upward/downward displaced. The endplate of the adjacent vertebral body exhibited fibrotic change. Treated bodies with vacuum clefts and level A location (T9, T11, T12, and L1) had higher probability of developing nonunion of the cement with statistical significance. The probability of nonunion cement in severe collapsed bodies might be higher than that of union cement in mild collapsed ones, but was not statistically significant. Fluid sign in the treated body represents unhealed bone-cement interface. The location of the treated vertebral body and existence of vacuum cleft in the treated bodies may be important factors influencing the nonunion of cement. (orig.)

Solidification and performance of cement doped with phenol

International Nuclear Information System (INIS)

Vipulanandan, C.; Krishnan, S.

1991-01-01

Treating mixed hazardous wastes using the solidification/stabilization technology is becoming a critical element in waste management planning. The effect of phenol, a primary constituent in many hazardous wastes, on the setting and solidification process of Type I Portland cement was evaluated. The leachability of phenol from solidified cement matrix (TCLP test) and changes in mechanical properties were studied after curing times up to 28 days. The changes in cement hydration products due to phenol were studied using the X-ray diffraction (XRD) powder technique. Results show that phenol interferes with initial cement hydration by reducing the formation of calcium hydroxide and also reduces the compressive strength of cement. A simple model has been proposed to quantify the phenol leached from the cement matrix during the leachate test

Resistance to fracture of endodontically treated premolars restored with glass ionomer cement or acid etch composite resin: An in vitro study

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B Ranga

2010-01-01

Full Text Available Aim: Due to the weakness of endodontically treated posterior teeth requires more strengthened restoration to withstand occlusal forces. The purpose of the present study was to determine and compare the resistance to fracture of endodontically treated maxillary 1 st premolars restored with different materials in mesio-occluso-distal (MOD cavity preparations. Materials and Methods: MOD cavity preparations in 80 endodontically treated maxillary 1 st premolars were restored using four different methods. Fiber rings were filled with stone plaster and the teeth were placed into the plaster up to the level of cemento-enamel junction. The teeth were grouped according to restorative method, mounted in an Instrom T.T. machine, and the buccal walls subjected to a slowly increasing compressive force until fracture occurred. Result: The force of fracture of the walls of each tooth was recorded and the results in the various groups compared. All teeth fractured in a similar manner irrespective of the restorative method used. Conclusion: The resistance to the fracture of the teeth was the same when they were stored with glass ionomer cement as a base over which composite resin was placed. When the entire cavities were filled with glass ionomer cement, the resistance to fracture of the teeth decreased significantly compared with the acid etch resin technique.

Soil-Water Characteristic Curves of Red Clay treated by Ionic Soil Stabilizer

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Cui, D.; Xiang, W.

2009-12-01

The relationship of red clay particle with water is an important factor to produce geological disaster and environmental damage. In order to reduce the role of adsorbed water of red clay in WuHan, Ionic Soil Stabilizer (ISS) was used to treat the red clay. Soil Moisture Equipment made in U.S.A was used to measure soil-water characteristic curve of red clay both in natural and stabilized conditions in the suction range of 0-500kPa. The SWCC results were used to interpret the red clay behavior due to stabilizer treatment. In addition, relationship were compared between the basic soil and stabilizer properties such as water content, dry density, liquid limit, plastic limit, moisture absorption rate and stabilizer dosages. The analysis showed that the particle density and specific surface area increase, the dehydration rate slows and the thickness of water film thins after treatment with Ionic Soil Stabilizer. After treatment with the ISS, the geological disasters caused by the adsorbed water of red clay can be effectively inhibited.

Performance study and influence of radiation emission energy and soil contamination level on γ-radiation shielding of stabilised/solidified radionuclide-polluted soils

International Nuclear Information System (INIS)

Falciglia, Pietro P.; Puccio, Valentina; Romano, Stefano; Vagliasindi, Federico G.A.

2015-01-01

This work focuses on the stabilisation/solidification (S/S) of radionuclide-polluted soils at different 232 Th levels using Portland cement alone and with barite aggregates. The potential of S/S was assessed applying a full testing protocol and calculating γ-radiation shielding (γRS) index, that included the measurement of soil radioactivity before and after the S/S as a function of the emission energy and soil contamination level. The results indicate that setting processes are strongly dependent on the contaminant concentration, and for contamination level higher than 5%, setting time values longer than 72 h. The addition of barite aggregates to the cement gout leads to a slight improvement of the S/S performance in terms of durability and contaminant leaching but reduces the mechanical resistance of the treated soils samples. Barite addition also causes an increase in the γ-rays shielding properties of the S/S treatment up to about 20%. Gamma-ray measurements show that γRS strongly depends on the energy, and that the radioactivity with the contamination level was governed by a linear trend, while, γRS index does not depend on the radionuclide concentration. Results allow the calculated γRS values and those available from other experiments to be applied to hazard radioactive soil contaminations. - Highlights: • We assess the effects of 232 Th contamination on performance of S/S treated soil. • We assess the γ-radiation shielding of the S/S materials as a function of energy. • We report a full testing protocol for assessing S/S resistance performance. • Emission energy influences the γ radiation shielding of the S/S. • Barite gives high γ-radiation shielding and low contaminant leaching

Phase I - Laboratory Study Effects of Cement Grout Structures on Colloid Formation from SRS Soils

International Nuclear Information System (INIS)

Serkiz, S.M.

2001-01-01

Studies were conducted to better understand the influence of grout structures and fills on colloid formation. Low-Level Waste is disposed in concrete vaults and trenches at the E-Area Low-Level Waste Facility (LLWF). Two types of enhanced trench disposal are approved for use including; Intimately-Mixed Cement-Stabilized waste forms, such as Ashcrete and Blowcrete resulting from operation of the Consolidated Incinerator Facility, and Cement-Stabilized Encapsulated waste, where waste forms (e.g., contaminated equipment) will be surrounded by a grout or other cementitious material. The presence of concrete structures and process of grouting in trenches are expected to generate colloids, both from the grout itself and as a result of the interactions of these cementitious materials and their degradation products with the surrounding soils. The extent of occurrence, mobility, and influence on contaminant transport of colloidal materials in aquifer systems is the subject of this study. The intent of this study is not to modify the PA but to aid in our understanding of the significance of this phenomenon. Information generated in this study will help in considering whether colloid-enhanced contaminant migration should be considered in establishing waste acceptance criteria and in the design and development of waste disposal systems

Forecasting the compressive strength of soil-concretedepending on ...

African Journals Online (AJOL)

One of the most important physical and mechanical properties of soil-concrete is the compressive strength. To this end we carried out a study of soil-concrete strength depending on its curing conditions and percentage of cement. For our study we used loam soil with the plasticity index of Ip = 12.3, Portland cement of type I, ...

compressibility characteristics of compacted black cotton soil treated

African Journals Online (AJOL)

eobe

E-mail addresses: 1111 aeberemu@yahoo.com, 2222sadat1010@live.com. Abstract. One dimensional consolidation studies on compacted black cotton soil treated with up to 16% rice .... 80% of the organic matter of the husk is burnt off and.

Method and Mechanisms of Soil Stabilization Using Electric Arc Furnace Dust

Science.gov (United States)

Al-Amoudi, Omar S. Baghabra; Al-Homidy, Abdullah A.; Maslehuddin, Mohammed; Saleh, Tawfik A.

2017-04-01

This paper reports the method and mechanism for improving the strength of marl and desert sand utilizing electric arc furnace dust (EAFD), an industrial by-product, in lieu of cement or lime. EAFD was used in conjunction with a small quantity (2%) of cement. The mechanical properties and durability characteristics of marl and sand mixed with 2% cement plus 5-, 10-, 20- or 30%-EAFD, by weight of the soil, were evaluated. The soil-cement-EAFD mixtures were used to determine their unconfined compressive strength (UCS), soaked California Bearing Ratio (CBR) and durability. The risk of leaching of toxic heavy metals, such as lead and cadmium, from the stabilized soils to the groundwater was also investigated. The mechanisms of stabilization of the selected soils due to the use of EAFD along with a small quantity of cement are also elucidated. The usage of 20 to 30% EAFD with 2% cement was noted to considerably improve the mechanical properties and durability of both marl and sand.

Evaluating continuous application of treated sludge on soil and plant productivity

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Ahmed Al-Busaidi

2018-01-01

Full Text Available Kala Compost is a mixture of treated sewage bio-solids and green wastes. It can improve soil fertility and plant growth. However, long-term application of treated sewage bio-solids could result in heavy metals accumulation and some health problems. e objective of this study was to evaluate the e ect of a long run application of Kala compost mixed with chemical fertilizer on soil and plant productivity. Soil and plant (mainly cucumber samples were taken from 12 greenhouses that received Kala compost continuously for the last ve years. No symptoms of physical or chemical problems were observed in the greenhouses and measured soil samples. Moreover, the soil had su cient values of di erent nutrients for plant growth and all measured micronutrients (heavy metals were within the safe limit and below the range of the international standards. An excellent growth was observed in all grown plants and no symptoms of elements de ciency were found. Chemical analysis of fruit samples did not show any accumulation of heavy metals and all measured elements were within the safe limit and did not exceed the international standards. It can be concluded that Kala compost was a good media for plant growth that can enrich the soil with di erent elements needed for higher yield. However, more monitoring is needed with treated bio-solid application but good management could be the key to avoid any adverse e ect of any contaminant.

Studies on diffusion of 137Cs in cement mortar

International Nuclear Information System (INIS)

Takebe, Shinichi; Shimooka, Kenji; Wadachi, Yoshiki; Kuramoto, Yuzuru.

1989-12-01

Penetration experiment of 137 Cs into the impermeable cement mortar which has been treated by the impermeable reagent (XYPEX reagent) was carried out in order to advance the performance of engineered barrier for Low Level Radioactive Waste. The result showed that the radioactive concentration at deeper region in the impermeable cement mortar specimen was decreased about 1 order of magnitude below that in the untreated specimen. Diffusion coefficient calculated from the radioactive concentration of 137 Cs in the cement mortar specimen was 9.1 x 10 -5 cm 2 /day for untreated cement mortar specimen and 4.0 x 10 -5 cm 2 /day for the impermeable cement mortar specimen, respectively. Treatment of cement mortar by the impermeable reagent was found to be effective to reduce the value of appearent diffusion coefficient for 137 Cs in the cement mortar. (author)

1-D Compression Behaviour of Acid Sulphate Soils Treated with Alkali-Activated Slag.

Science.gov (United States)

Islam, Shahidul; Haque, Asadul; Bui, Ha Hong

2016-04-15

Improvements of soft soils by mechanically mixing cementitious additives have been widely practised for construction of infrastructure. Mixing of additives improves strength and compressibility properties of soils through the development of soil structure. This study investigates the 1-D compression behaviour of alkali-activated slag treated acid sulphate soils (ASS) cured up to 365 days. The void ratio-logarithm of pressure (e-logσ') behaviour of treated ASS, including the destructuration behaviour, with additive contents and curing time have been analysed. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses have been undertaken to explain the observed variations of the 1-D compression behaviour. This paper presents the results of these analyses in view of obtaining an insight into the 1-D compression behaviour of treated ASS with the help of mineralogical analysis.

Cementation unit for radioactive wastes

International Nuclear Information System (INIS)

Dellamano, Jose Claudio; Vicente, Roberto; Lima, Jose Rodrigues de

2001-01-01

This communication describes the waste cementation process and facility developed at Instituto de Pesquisas Energeticas e Nucleares - IPEN. The process is based on 200 litres batch operation, in drum mixing, with continuous cement feeding. The equipment is a single recoverable helicoidal mixer and a turning table that allows the drum to rotate during the mixing operation, simulating a planetary mixer. The facility was designed to treat contact handled liquids and wet solid wastes, but can be adapted for shielded equipment and remote operation. (author)

Experimental Calcium Silicate-Based Cement with and without Zirconium Oxide Modulates Fibroblasts Viability.

Science.gov (United States)

Slompo, Camila; Peres-Buzalaf, Camila; Gasque, Kellen Cristina da Silva; Damante, Carla Andreotti; Ordinola-Zapata, Ronald; Duarte, Marco Antonio Hungaro; de Oliveira, Rodrigo Cardoso

2015-01-01

The aim of this study was to verify whether the use of zirconium oxide as a radiopacifier of an experimental calcium silicate-based cement (WPCZO) leads to cytotoxicity. Fibroblasts were treated with different concentrations (10 mg/mL, 1 mg/mL, and 0.1 mg/mL) of the cements diluted in Dulbecco's modified Eagle's medium (DMEM) for periods of 12, 24, and 48 h. Groups tested were white Portland cement (WPC), white Portland cement with zirconium oxide (WPCZO), and white mineral trioxide aggregate Angelus (MTA). Control group cells were not treated. The cytotoxicity was evaluated through mitochondrial-activity (MTT) and cell-density (crystal violet) assays. All cements showed low cytotoxicity. In general, at the concentration of 10 mg/mL there was an increase in viability of those groups treated with WPC and WPCZO when compared to the control group (pcement with 20% zirconium oxide as the radiopacifier showed low cytotoxicity as a promising material to be exploited for root-end filling.

Bio-chemical properties of sandy calcareous soil treated with rice straw-based hydrogels

Directory of Open Access Journals (Sweden)

Houssni El-Saied

2016-06-01

The results obtained show that, application of the investigated hydrogels positively affects bio-chemical properties of the soil. These effects are assembled in the following: (a slightly decreasing soil pH, (b increasing cation exchange capacity (CEC of the soil indicating improvement in activating chemical reactions in the soil, (c increasing organic matter (OM, organic carbon, total nitrogen percent in the soil. Because the increase in organic nitrogen surpassed that in organic carbon, a narrower CN ratio of treated soils was obtained. This indicated the mineralization of nitrogen compounds and hence the possibility to save and provide available forms of N to growing plants, (d increasing available N, P and K in treated soil, and (e improving biological activity of the soil expressed as total count of bacteria and counts of Azotobacter sp., phosphate dissolving bacteria (PDB, fungi and actinomycetes/g soil as well as the activity of both dehydrogenase and phosphatase.

Permeability Characteristics of Compacted and Stabilized Clay with Cement, Peat Ash and Silica Sand

OpenAIRE

Seyed Esmaeil Mousavi; Leong Sing Wong

2016-01-01

The present paper investigates the influence of stabilization with cement, peat ash, and silica sand on permeability coefficient (kv) of compacted clay, using a novel approach to stabilize the clay with peat ash as a supplementary material of cement in the compacted and stabilized soil. In order to assess the mentioned influence, test specimens of both untreated and stabilized soil have been tested in the laboratory so that their permeability could be evaluated. Falling head and one dimension...

The Influence of Abutment Surface Treatment and the Type of Luting Cement on Shear Bond Strength between Titanium/Cement/Zirconia

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Beata Śmielak

2015-01-01

Full Text Available Objectives. The objectives of this study were to evaluate the shear bond strength of zirconia cylinders on a modified titanium surface using different luting cement types. Material and Methods. Eighty titanium disks were divided into two groups (n=40, which were treated with either grinding or a combination of sandblasting and grinding. Then, each group was subdivided into 4 groups (n=10 and the disks were bonded to disks of sintered zirconia using one of four cement types (permanent: composite cement; temporary: polycarboxylate cement, zinc-oxide-eugenol cement, and resin cement. Shear bond strength (SBS was measured in a universal testing machine. Fracture pattern and site characteristic were recorded. A fractographic analysis was performed with SEM. The chemical analysis of the composition of the fractures was performed using energy-dispersive X-ray spectroscopy (EDS. The results of the experiment were analyzed with two-way analysis of variance and Tukey post hoc test. Results. The highest mean values of SBS were achieved when grinding was combined with sandblasting and when composite cement was used (18.18 MPa. In the temporary cement group, the highest mean values of SBS were for polycarboxylate cement after grinding (3.57 MPa. Conclusion. The choice of cement has a crucial influence on the titanium-cement-zirconia interface quality.

Cement burns: retrospective study of 18 cases and review of the literature.

Science.gov (United States)

Poupon, M; Caye, N; Duteille, F; Pannier, M

2005-11-01

Cement is increasingly used in the construction industry, but the occurrence of cement burns is rarely reported. This retrospective study concerns patients treated for cement burns in our unit between 1997 and 2002. Eighteen patients 18-64 years of age, treated previously in our unit for cement burns, were interviewed by telephone for evaluation. The mean time since treatment was 39 months. Burns were predominantly seen on the lower limbs, and a third occurred during an accident on the job. All deep burns were excised, and 16 patients received grafts. Mean hospital stay was 10 days, and mean sick leave 2 months. Our study indicated that all patients were poorly informed about cement-related risks. Surgical treatment of full-thickness cement burns at diagnosis enables rapid healing with a minimum of sequelae and reduces the high socioeconomic costs resulting from these lesions. This study indicates once again the need to improve preventive measures; which are very often inadequate because of lack of awareness of risks.

Mapping the depth to ice-cemented ground in the high elevation Dry Valleys, Antarctica

Science.gov (United States)

Marinova, M.; McKay, C. P.; Heldmann, J. L.; Davila, A. F.; Andersen, D. T.; Jackson, A.; Lacelle, D.; Paulsen, G.; Pollard, W. H.; Zacny, K.

2011-12-01

The high elevation Dry Valleys of Antarctica provide a unique location for the study of permafrost distribution and stability. In particular, the extremely arid and cold conditions preclude the presence of liquid water, and the exchange of water between the ice-cemented ground and the atmosphere is through vapour transport (diffusion). In addition, the low atmospheric humidity results in the desiccation of the subsurface, forming a dry permafrost layer (i.e., cryotic soils which are dry and not ice-cemented). Weather data suggests that subsurface ice is unstable under current climatic conditions. Yet we do find ice-cemented ground in these valleys. This contradiction provides insight into energy balance modeling, vapour transport, and additional climate effects which stabilize subsurface ice. To study the driving factors in the stability and distribution of ice-cemented ground, we have extensively mapped the depth to ice-cemented ground in University Valley (1730 m; 77°S 51.8', 160°E 43'), and three neighbouring valleys in the Beacon Valley area. We measured the depth to ice-cemented ground at 15-40 locations per valley by digging soil pits and drilling until ice was reached; for each location 3-5 measurements within a ~1 m2 area were averaged (see figure). This high-resolution mapping of the depth to ice-cemented ground provides new insight on the distribution and stability of subsurface ice, and shows significant variability in the depth to ground ice within each valley. We are combining data from mapping the depth to ice-cemented ground with year-round, in situ measurements of the atmospheric and subsurface conditions, such as temperature, humidity, wind, and light, to model the local stability of ice-cemented ground. We are using this dataset to examine the effects of slopes, shading, and soil properties, as well as the suggested importance of snow recurrence, to better understand diffusion-controlled subsurface ice stability.

1-D Compression Behaviour of Acid Sulphate Soils Treated with Alkali-Activated Slag

Directory of Open Access Journals (Sweden)

Shahidul Islam

2016-04-01

Full Text Available Improvements of soft soils by mechanically mixing cementitious additives have been widely practised for construction of infrastructure. Mixing of additives improves strength and compressibility properties of soils through the development of soil structure. This study investigates the 1-D compression behaviour of alkali-activated slag treated acid sulphate soils (ASS cured up to 365 days. The void ratio-logarithm of pressure (e-logσ′ behaviour of treated ASS, including the destructuration behaviour, with additive contents and curing time have been analysed. X-ray diffraction (XRD and scanning electron microscopy (SEM analyses have been undertaken to explain the observed variations of the 1-D compression behaviour. This paper presents the results of these analyses in view of obtaining an insight into the 1-D compression behaviour of treated ASS with the help of mineralogical analysis.

Basic Aspects of Deep Soil Mixing Technology Control

Science.gov (United States)

Egorova, Alexandra A.; Rybak, Jarosław; Stefaniuk, Damian; Zajączkowski, Przemysław

2017-10-01

Improving a soil is a process of increasing its physical/mechanical properties without changing its natural structure. Improvement of soil subbase is reached by means of the knitted materials, or other methods when strong connection between soil particles is established. The method of DSM (Deep Soil Mixing) columns has been invented in Japan in 1970s. The main reason of designing cement-soil columns is to improve properties of local soils (such as strength and stiffness) by mixing them with various cementing materials. Cement and calcium are the most commonly used binders. However new research undertaken worldwide proves that apart from these materials, also gypsum or fly ashes can also be successfully implemented. As the Deep Soil Mixing is still being under development, anticipating mechanical properties of columns in particular soils and the usage of cementing materials in formed columns is very difficult and often inappropriate to predict. That is why a research is carried out in order to find out what binders and mixing technology should be used. The paper presents several remarks on the testing procedures related to quality and capacity control of Deep Soil Mixing columns. Soil improvement methods, their advantages and limitations are briefly described. The authors analyse the suitability of selected testing methods on subsequent stages of design and execution of special foundations works. Chosen examples from engineering practice form the basis for recommendations for the control procedures. Presented case studies concerning testing the on capacity field samples and laboratory procedures on various categories of soil-cement samples were picked from R&D and consulting works offered by Wroclaw University of Science and Technology. Special emphasis is paid to climate conditions which may affect the availability of performing and controlling of DSM techniques in polar zones, with a special regard to sample curing.

Influence of cementation on the deformation properties of bentonite/quartz buffer substance

International Nuclear Information System (INIS)

Pusch, R.

1977-06-01

Cementation, e.g.precipitation of crystalline or solid amorphous inorganic substance between individual grains, greatly affects the mechanical properties of fine-grained soils. As concerns the buffer mass with the composition suggested (10 weight percent bentonite and 90% quartz particles) the intergranular contact pressure between the quartz particles will not be able to cause 'pressure solution'. Also, the other possible cementation effects will be negligible with the exception of the process which leads to precipitation of SiO 2 dissolved from quartz particles and enriched in the interstitial pore space. This process and its consequences will be treated in this report. The nature of silica solution and precipitation is not known in detail. The chemical environment, temperature, pH and ion strength are known to be controlling factors which combine to make possible alternating solution and precipitation of silica. However, as shown by the case survey and the presented theoretical treatment the amount of precipitated SiO 2 will not be able to produce a brittle behaviour of the buffer mass even after thousands of years

characterization of soil and sediments parameters of oguta – izombe

African Journals Online (AJOL)

Prof

where the clayey lateritic soil with iron oxide cementation of soil particles provides an appreciable degree of ... need for groundwater protection against pollution. Geological ..... consists of clayey laterite with iron oxide coating and cementation ...

Integrating Electrokinetic and Bioremediation Process for Treating Oil Contaminated Low Permeability Soil

OpenAIRE

Surya Ramadan Bimastyaji; Jatnika Effendi Agus; Helmy Qomarudin

2018-01-01

Traditional oil mining activities always ignores environmental regulation which may cause contamination in soil and environment. Crude oil contamination in low-permeability soil complicates recovery process because it requires substantial energy for excavating and crushing the soil. Electrokinetic technology can be used as an alternative technology to treat contaminated soil and improve bioremediation process (biostimulation) through transfer of ions and nutrient that support microorganism gr...

Physical-chemical effects of irrigation with treated wastewater on Dusky Red Latosol soil

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Vanessa Ribeiro Urbano

2015-11-01

Full Text Available The current water crisis underlines the importance of improving water management. The use of effluent from secondary treatment in agriculture can reduce the discharge of effluent into natural bodies and provide nutrients to crops. This study evaluated the physical and chemical properties of a Dusky Red Latosol soil that had been irrigated with treated wastewater. Conducted at the Center of Agricultural Sciences (CCA of Federal University of São Carlos (UFSCar, in Araras/São Paulo/Brazil, 18 undisturbed soil samples were collected and deposited on a constant-head permeameter in order to simulate the irrigation of five growth cycles of lettuce (Lactuca sativa L., organized in five different treatments and one control group. For each treatment 0.58 L, 1.16 L, 1.74 L, 2.32 L, and 2.90 L of treated wastewater and distilled water were applied . The treated wastewater came from a domestic waste treatment plant. After the water filtered through the soil, samples of treated wastewater were collected for analyses of electrical conductivity (EC, sodium adsorption ratio (SAR, turbidity, pH, Na, K, Mg, P and Ca and, in the soil the granulometry, complete fertility, exchangeable sodium percentage (ESP and saturated hydraulic conductivity (Ksat. The Ksat decreased, but did not alter the infiltration of water and nutrients in the soil. The concentration of nutrients in the soil increased, including Na, which raises the need for monitoring soil’s salinity. In conclusion, the application of wastewater did not cause damage to the physical properties of the soil, but resulted in a tendency towards salinization.

Effect of Rice Husk Ash on Cement Stabilized Laterite

OpenAIRE

Musa ALHASSAN; Alhaji Mohammed MUSTAPHA

2007-01-01

Laterite soil collected from Maikunkele area of Minna, classified as an A-7-6 on AASHTO classification, was stabilized with 2-8% cement by weight of the dry soil. Using British Standard Light (BSL) compaction energy, the effect of Rice Husk Ash (RHA) on the soil was investigated with respect to compaction characteristics, California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS) tests. Results obtained, indicate a general decrease in Maximum Dry Density (MDD) and increase in Op...

Effect of Cement Replacement with Carbide Waste on the Strength of Stabilized Clay Subgrade

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Muntohar A.S.

2016-03-01

Full Text Available Cement is commonly used for soil stabilization and many other ground improvement techniques. Cement is believed to be very good to improve the compressive and split-tensile strength of clay subgrades. In some application cement could be partly or fully replaced with carbide waste. This research is to study the effectiveness of the cement replacement and to find the maximum carbide waste content to be allowed for a clay subgrade. The quantities of cement replaced with the carbide waste were 30, 50, 70, 90, and 100% by its mass. The results show that replacing the cement with carbide waste decreased both the compressive and split tensile strength. Replacing cement content with carbide waste reduced its ability for stabilization. The carbide waste content should be less than 70% of the cement to provide a sufficient stabilizing effect on a clay subgrade.

Expansion control for cementation of incinerated ash

International Nuclear Information System (INIS)

Nakayama, T.; Suzuki, S.; Hanada, K.; Tomioka, O.; Sato, J.; Irisawa, K.; Kato, J.; Kawato, Y.; Meguro, Y.

2015-01-01

A method, in which incinerated ash is solidified with a cement material, has been developed to dispose of radioactive incinerated ash waste. A small amount of metallic Al, which was not oxidized in the incineration, existed in the ash. When such ash was mixed with a cement material and water, alkaline components in the ash and the cement were dissolved in the mixing water and then metallic Al reaction with the alkaline compounds resulted in generation of H 2 . Because the H 2 generation began immediately just after the mixing, H 2 bubbles pushed up the mixed grout material and an expanded solidified form was obtained. The expansion leads to lowering the strength of the solidified form and making harmful void. In this study, we tried to control H 2 generation from the reaction of metallic Al in the cementation by means of following two methods, one was a method to let metallic Al react prior to the cementation and the other was a method to add an expansion inhibitor that made an oxide film on the surface of metallic Al. In the pre-treatment, the ash was soaked in water in order to let metallic Al react with it, and then the ash with the immersion solution was dried at 105 Celsius degrees. The pre-treated ash was mixed with an ordinary portland cement and water. The inhibitor of lithium nitrite, sodium nitrite, phosphoric acid, or potassium dihydrogen phosphate was added at the mixing process. The solidified forms prepared using the pre-treated ash and lithium nitrite were not expanded. Phosphoric acid and sodium nitrite were effective for expansion control, but potassium dihydrogen phosphate did not work. (authors)

Soil quality in a cropland soil treated with wood ash containing charcoal

Science.gov (United States)

Omil, Beatriz; Balboa, Miguel A.; Fonturbel, M. Teresa; Gartzia-Bengoetxea, Nahia; Arias-González, Ander; Vega, Jose A.; Merino, Agustin

2014-05-01

The strategy of the European Union "Europe 2020" states that by 2020, 20% of final energy consumption must come from renewables. In this scenario, there is an increasing use of biomass utilization for energy production. Indeed, it is expected that the production of wood-ash will increase in coming years. Wood ash, a mixture of ash and charcoal, generated as a by-product of biomass combustion in power plants, can be applied to soil to improve the soil quality and crop production. Since the residue contains significant content of charcoal, the application of mixed wood ash may also improve the SOM content and soil quality in the long term, in soils degraded as a consequence of intensive management. The objective of this study was asses the changes in SOM quality and soil properties in a degraded soils treated with wood ash containing charcoal. The study was carried out in a field devoted to cereal crops during the last decades. The soil was acidic (pH 4.5) with a low SOC content (3 %) and fine texture. The experiment was based on a randomised block design with four replicates. Each block included the following four treatments: Control, 16 Mg fly wood ash ha-1, 16 Mg mixed wood ash ha-1 (16 Mg) and 32 Mg mixed wood ash ha-1 (32 Mg). The application was carried out once. The ash used in the study was obtained from a thermal power plant and was mainly derived from the combustion of Pinus radiata bark and branches. The wood ash is highly alkaline (pH= 10), contains 10 % of highly condensed black carbon (atomic H/C ratio solid state 13C CPMAS NMR and Differential Scanning Calorimetry (DSC). These techniques were applied in bulk samples and aggregates of different sizes. The changes in microbial activity were studied by analysis of microbial biomass C and basal respiration. The soil bacterial community was studied by the Biolog method. Several physical properties, such soil aggregate distribution, hydraulic conductivity and available water contente were also determined

Plant availability of trace elements in sewage sludge-treated soils: methodology¹

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Giuliano Marchi

2011-08-01

Full Text Available Synthetic root exudates were formulated based on the organic acid composition of root exudates derived from the rhizosphere of aseptically grown corn plants, pH of the rhizosphere, and the background chemical matrices of the soil solutions. The synthetic root exudates, which mimic the chemical conditions of the rhizosphere environment where soil-borne metals are dissolved and absorbed by plants, were used to extract metals from sewage-sludge treated soils 16 successive times. The concentrations of Zn, Cd, Ni, Cr, and Cu of the sludge-treated soil were 71.74, 0.21, 15.90, 58.12, and 37.44 mg kg-1, respectively. The composition of synthetic root exudates consisted of acetic, butyric, glutaric, lactic, maleic, propionic, pyruvic, succinic, tartaric, and valeric acids. The organic acid mixtures had concentrations of 0.05 and 0.1 mol L-1 -COOH. The trace elements removed by successive extractions may be considered representative for the availability of these metals to plants in these soils. The chemical speciation of the metals in the liquid phase was calculated; results showed that metals in sludge-treated soils were dissolved and formed soluble complexes with the different organic acid-based root exudates. The most reactive organic acid ligands were lactate, maleate, tartarate, and acetate. The inorganic ligands of chloride and sulfate played insignificant roles in metal dissolution. Except for Cd, free ions did not represent an important chemical species of the metals in the soil rhizosphere. As different metals formed soluble complexes with different ligands in the rhizosphere, no extractor, based on a single reagent would be able to recover all of the potentially plant-available metals from soils; the root exudate-derived organic acid mixtures tested in this study may be better suited to recover potentially plant-available metals from soils than the conventional extractors.

Use of antibiotic-loaded cement in total knee arthroplasty.

OpenAIRE

Hinarejos Gómez, Pedro Angel; Guirro Castellnou, Pau; Puig Verdié, Luís; Torres Claramunt, Raúl; Leal Blanquet, Joan; Sánchez Soler, JF.; Monllau García, Juan Carlos

2015-01-01

Bone cement has the capacity to release antibiotic molecules if any antibiotic is included in it, and these elution properties are improved as cement porosity is increased. In vitro studies have shown high local antibiotic concentration for many hours or few days after its use. Antibiotic loaded bone cement (ALBC) is helpful when treating an infection in total knee arthroplasty (TKA) revision surgery. The purpose of this paper was to review the evidence for the routine use of ALBC in TKA in t...

Ground temperatures in ice-cemented ground at Linnaeus Terrace, Dry Valleys, Antarctica, Version 1

Data.gov (United States)

National Aeronautics and Space Administration — Soil temperatures were measured with Campbell 107 soil thermistors. Thermistors were placed at 0, 17, 23 (just above the ice-cemented permafrost) and 40 cm depth. To...

Eucalyptus grandis AND Eucalyptus dunnii USE FOR WOOD-CEMENT PANELS MANUFACTURING

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Setsuo Iwakiri

2008-03-01

Full Text Available This research evaluated the potential use of Eucalyptus grandis and Eucalyptus dunnii wood for wood-cement panelsmanufacturing. The boards were manufactured at the density of 1,20 g/cm³, using portland cement as mineral bonding and woodfurnish without treatment, treated in cold water and hot water. The wood furnish of Pinus taeda was used as control. The resultsindicated that it is not necessary to treat E. grandis and E. dunni wood for wood-cement board manufacturing. In relation to woodspecies, the board manufactured with E. dunnii showed lower values of mechanical properties. However, boards manufactured of E.grandis wood showed satisfactory results in comparison to boards of P. taeda and the referenced values of BISON process and otherproducts cited in the pertnent literature, indicating the high potential for wood-cement board manufacture of this tree species.

Soil mixing design methods and construction techniques for use in high organic soils : [summary].

Science.gov (United States)

2015-10-01

The soils which serve as foundations for construction projects may be roughly classified as : inorganic or organic. Inorganic soils vary in firmness and suitability for construction. Soft : or loose inorganic soils may be stabilized using cement or s...

Assessing the Effect of Cement Dust Emission on the Physicochemical Nature of Soil around Messebo area, Tigray, North Ethopia

Directory of Open Access Journals (Sweden)

SAMUEL ESTIFANOS

2012-12-01

Full Text Available Twenty six soil samples were collected around the vicinity of Messebo cement factory in Mekelle, Ethiopia from 0-5 and 5-15 cm depths and determined their physicochemical properties and heavy metals contents. The results indicated that the soils are calcareous having sandy loam to loamy sand texture. The top and lower parts of the soil are found to be alkaline with mean pH 8.97 and 8.93; EC 223.06 and 88.22 µS/cm respectively. The cation exchange capacity of the top soil (0-5cm range from 9 to 27 mmolc kg-1, while the exchangeable Ca and Mg range from 6.4 to 16 and 2.2 to 5.0 mmolc kg- 1 respectively. The average Ca concentration values for the upper and lower soil depths are 418ppm and 404.36ppm respectively. Water extractable analysis results verify the degree of leaching of the metals from anthropogenic source. Geoaccumulation index confirms that the two soil depths are similarly categorized as very heavily contaminated with (As, Cr, Co and Ni and moderately to heavily contaminated with (Cu, Pb and Mo whereas the top part is moderately contaminated with Zn. Based on Enrichment Factor (EF, both soil depths have moderate enrichment with Pb ( 2 EF >20, very high enrichment with Cr (2040. The severe contamination is evident to the east western direction towards which the wind blow predominantly.

Impact of treated wastewater for irrigation on soil microbial communities.

Science.gov (United States)

Ibekwe, A M; Gonzalez-Rubio, A; Suarez, D L

2018-05-01

The use of treated wastewater (TWW) for irrigation has been suggested as an alternative to use of fresh water because of the increasing scarcity of fresh water in arid and semiarid regions of the world. However, significant barriers exist to widespread adoption due to some potential contaminants that may have adverse effects on soil quality and or public health. In this study, we investigated the abundance and diversity of bacterial communities and the presence of potential pathogenic bacterial sequences in TWW in comparison to synthetic fresh water (SFW) using pyrosequencing. The results were analyzed using UniFrac coupled with principal coordinate analysis (PCoA) to compare diversity and abundance of different bacterial groups in TWW irrigated soils to soils treated with SFW. Shannon diversity index values (H') suggest that microbial diversity was not significantly different (P<0.086) between soils with TWW and SFW. Pyrosequencing detected sequences of 17 bacterial phyla with Proteobacteria (32.1%) followed by Firmicutes (26.5%) and Actinobacteria (14.3%). Most of the sequences associated with nitrifying bacteria, nitrogen-fixing bacteria, carbon degraders, denitrifying bacteria, potential pathogens, and fecal indicator bacteria were more abundant in TWW than in SFW. Therefore, TWW effluent may contain bacterial that may be very active in many soil functions as well as some potential pathogens. Published by Elsevier B.V.

Reduced survival for uncemented compared to cemented total hip arthroplasty after operatively treated acetabular fractures.

Science.gov (United States)

Clarke-Jenssen, John; Westberg, Marianne; Røise, Olav; Storeggen, Stein Arne Øvre; Bere, Tone; Silberg, Ingunn; Madsen, Jan Erik

2017-11-01

Post traumatic arthritis and avascular necrosis of the femoral head are common complications after operatively treated acetabular fractures. This may cause severe disabilities for the patient, necessitating a total hip arthroplasty. Even though an arthroplasty may provide good symptomatic relief, the long-term results are more uncertain and no consensus exists according to preferred prosthetic designs. With this cohort study, we aimed to investigate the medium to long term arthroplasty survival and clinical results of total hip arthroplasty after operatively treated acetabular fractures. We included 52 patients treated with a secondary total hip arthroplasty at a median of 2.4 (0.1-14.1) years after an operatively treated acetabular fracture. The median age was 54 (11-82) years. Cemented arthroplasty was used for 33 patients, 10 patients had an uncemented arthroplasty and 9 patients received a hybrid arthroplasty. Average follow up was 8.0 (SD 5.0) years. Ten-year revision free arthroplasty survival was 79%. Uncemented arthroplasties had a significantly worse 10-year survival of 57%. Arthroplasties performed at a centre without a pelvic fracture service also had a significantly worse 10-years survival of 51%. Cox regression showed similar results with an 8-fold increase in risk of revision for both uncemented arthroplasties and operations performed at a non-pelvic trauma centre. Total hip arthroplasty secondary to an operatively treated acetabular fracture provides good symptomatic relief. These patients are, however, complex cases and are probably best treated at specialist centres with both pelvic trauma surgeons and arthroplasty surgeons proficient in complex revisions present. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pull-out bond strength of a self-adhesive resin cement to NaOCl-treated root dentin: effect of antioxidizing agents

Directory of Open Access Journals (Sweden)

Maryam Khoroushi

2014-05-01

Full Text Available Objectives This study evaluated the effect of three antioxidizing agents on pull-out bond strengths of dentin treated with sodium hypochlorite. Materials and Methods Root canals of 75 single-rooted human teeth were prepared. Fifteen teeth were irrigated with normal saline for a negative control group, and the remaining 60 teeth (groups 2 - 5 with 2.5% NaOCl. The teeth in group 2 served as a positive control. Prior to post cementation, the root canals in groups 3 - 5 were irrigated with three antioxidizing agents including 10% rosmarinic acid (RA, Baridge essence, 10% hesperidin (HPN, Sigma, and 10% sodium ascorbate hydrogel (SA, AppliChem. Seventy-five spreaders (#55, taper .02, Produits Dentaires S.A were coated with silica and silanized with the Rocatec system and ceramic bond. All the prepared spreaders were cemented with a self-adhesive resin cement (Bifix SE, Voco Gmbh in the prepared canals. After storage in distilled water (24 h/37℃, the spreaders were pulled out in a universal testing machine at a crosshead speed of 1.0 mm/min. Pull-out strength values were analyzed by one-way ANOVA and Tukey's HSD test (α = 0.05. Results There were significant differences between study groups (p = 0.016. The highest pull-out strength was related to the SA group. The lowest strength was obtained in the positive control group. Conclusions Irrigation with NaOCl during canal preparation decreased bond strength of resin cement to root dentin. Amongst the antioxidants tested, SA had superior results in reversing the diminishing effect of NaOCl irrigation on the bond strength to root dentin.

Cement Leakage in Percutaneous Vertebral Augmentation for Osteoporotic Vertebral Compression Fractures: Analysis of Risk Factors.

Science.gov (United States)

Xie, Weixing; Jin, Daxiang; Ma, Hui; Ding, Jinyong; Xu, Jixi; Zhang, Shuncong; Liang, De

2016-05-01

The risk factors for cement leakage were retrospectively reviewed in 192 patients who underwent percutaneous vertebral augmentation (PVA). To discuss the factors related to the cement leakage in PVA procedure for the treatment of osteoporotic vertebral compression fractures. PVA is widely applied for the treatment of osteoporotic vertebral fractures. Cement leakage is a major complication of this procedure. The risk factors for cement leakage were controversial. A retrospective review of 192 patients who underwent PVA was conducted. The following data were recorded: age, sex, bone density, number of fractured vertebrae before surgery, number of treated vertebrae, severity of the treated vertebrae, operative approach, volume of injected bone cement, preoperative vertebral compression ratio, preoperative local kyphosis angle, intraosseous clefts, preoperative vertebral cortical bone defect, and ratio and type of cement leakage. To study the correlation between each factor and cement leakage ratio, bivariate regression analysis was employed to perform univariate analysis, whereas multivariate linear regression analysis was employed to perform multivariate analysis. The study included 192 patients (282 treated vertebrae), and cement leakage occurred in 100 vertebrae (35.46%). The vertebrae with preoperative cortical bone defects generally exhibited higher cement leakage ratio, and the leakage is typically type C. Vertebrae with intact cortical bones before the procedure tend to experience type S leakage. Univariate analysis showed that patient age, bone density, number of fractured vertebrae before surgery, and vertebral cortical bone were associated with cement leakage ratio (Pcement leakage are bone density and vertebral cortical bone defect, with standardized partial regression coefficients of -0.085 and 0.144, respectively. High bone density and vertebral cortical bone defect are independent risk factors associated with bone cement leakage.

Method and Mechanisms of Soil Stabilization Using Electric Arc Furnace Dust

OpenAIRE

Al-Amoudi, Omar S. Baghabra; Al-Homidy, Abdullah A.; Maslehuddin, Mohammed; Saleh, Tawfik A.

2017-01-01

This paper reports the method and mechanism for improving the strength of marl and desert sand utilizing electric arc furnace dust (EAFD), an industrial by-product, in lieu of cement or lime. EAFD was used in conjunction with a small quantity (2%) of cement. The mechanical properties and durability characteristics of marl and sand mixed with 2% cement plus 5-, 10-, 20- or 30%-EAFD, by weight of the soil, were evaluated. The soil-cement-EAFD mixtures were used to determine their unconfined com...

Improvement of CBR and compaction characteristics of bauxite rich dispersive soils available in pakistan: a case study of khushab soil

International Nuclear Information System (INIS)

Batool, S.

2016-01-01

Dispersion of dispersive soil occurs when it comes in contact with water and clay particles deflocculate and disperse away from each other. Thus dispersive soils undergo erosion under low seepage velocity leading to instability problems of slopes and earth retaining structures. The amount of dispersion depends upon the mineralogy and geochemistry of clayey soil as well as the dissolved salts of the pore fluid. The dispersivity of the soil mainly depends on the amount of exchangeable sodium present in its formation. Under saturated conditions, the attractive forces are less than the repulsive forces and this will help the particles to disperse and go into colloidal suspension. The use of chemical stabilizers such as lime and cement to bind the clay particles and reduce the dispersivity of soil and to improve the compaction and CBR characteristics of bauxite rich dispersive soil present in Khushab district have been studied in this research. Soil behavior was studied after addition of 2%, 4%, 6% and 8% Lime and Cement, at optimum level of 6% for Lime and Cement; it has been observed that the CBR and compaction characteristics of Khushab soil have been improved. (author)

Cemented Horizons and Hardpans in the Coastal Tablelands of Northeastern Brazil

Directory of Open Access Journals (Sweden)

João Bosco Vasconcellos Gomes

Full Text Available ABSTRACT Horizons with varying degrees of cementation are a common feature of the soils from the coastal tablelands of Northeastern Brazil. In most cases, these horizons are represented by the following subsurface horizons: fragipan, duripan, ortstein, and placic. The aims of this study were to analyze differences regarding the development and the degree of expression of cementation in soils from the coastal tablelands of Northeastern Brazil: Planossolo Háplico (p-SX, Espodossolo Humilúvico (p-EK, Espodossolo Ferrihumilúvico (p-ESK, and Argissolo Acinzentado (p-PAC pedons. The pedons studied displayed features related to drainage impediments. The cemented horizons from p-SX and p-EK had the same designation (Btgm, displaying a duric character that coincided with gleization features and are under podzolized horizons. In the p-ESK, the podzolization process is of such magnitude that it leads to the cementation of its own spodic horizons, which were both of the ortstein type (Bhsx and Bsm. In the p-PAC cementation is observed in two placic horizons and in the Btx/Bt horizon, as well as in the upper parts of the Bt/Btx horizon. Analysis of the micrographies from the cemented horizons showed predominance of a low porosity matrix. Such porosity is relatively greater in the horizons of “x” subscript than in the horizons with duric character. The Fe segregation lines were notable in the cemented horizons from p-EK and p-PAC, which corroborates the presence of placic horizons in such pedons. The preponderance of kaolinite in the clay fraction was widely verified in all the cemented horizons analyzed. Water immersion tests were the criteria adopted to define the duric character of the Btgm horizons from p-SX and p-EK, and in the Bsm horizon from the p-ESK. These tests were also used to confirm field morphology. In most cases, the maximum values of Fe, Al, and Si, determined by different extractions, occurred in positions overlaying the cemented

Effect of irrigation with treated wastewater on soil chemical properties and infiltration rate.

Science.gov (United States)

Bedbabis, Saida; Ben Rouina, Béchir; Boukhris, Makki; Ferrara, Giuseppe

2014-01-15

In Tunisia, water scarcity is one of the major constraints for agricultural activities. The reuse of treated wastewater (TWW) in agriculture can be a sustainable solution to face water scarcity. The research was conducted for a period of four years in an olive orchard planted on a sandy soil and subjected to irrigation treatments: a) rain-fed conditions (RF), as control b) well water (WW) and c) treated wastewater (TWW). In WW and TWW treatments, an annual amount of 5000 m(3) ha(-1) of water was supplied to the orchard. Soil samples were collected at the beginning of the study and after four years for each treatment. The main soil properties such as electrical conductivity (EC), pH, soluble cations, chloride (Cl(-)), sodium adsorption ratio (SAR), organic matter (OM) as well as the infiltration rate were investigated. After four years, either a significant decrease of pH and infiltration rate or a significant increase of OM, SAR and EC were observed in the soil subjected to treated wastewater treatment. Copyright © 2013. Published by Elsevier Ltd.

Use of soil-cement block as an alternative to the construction of popular houses

International Nuclear Information System (INIS)

Azevedo, A.R.G.; Alexandre, J.; Ribeiro Junior, J. R.

2012-01-01

The construction industry in Brazil, after several years in decline, is currently undergoing a growing trend, which can be observed daily by the large number of construction sites around the country, whether public or private. However when it comes to developments in methods of construction sector appears that little progress was made, built in a very rudimentary compared to other countries and we still have some concerns with the new technology, whether raw materials or methods of construction, which eventually generate large waste caused by the lack of streamlining processes and increasing the cost of works in general, and in this context that this paper proposes a study of the constructive model based on the use of soil-cement masonry, which comes as an alternative more economical, with a strong environmental appeal and the growing demand for building low cost houses (ideal for this constructive model). (author)

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

Air pollution control (APC) residues from municipal solid waste incineration (MSWI) are considered hazardous waste and need pretreatment prior to possible reuse. Here, two MSWI APC residues, from which the most mobile fraction of heavy metals and salts has been removed by carbonation and/or elect......Air pollution control (APC) residues from municipal solid waste incineration (MSWI) are considered hazardous waste and need pretreatment prior to possible reuse. Here, two MSWI APC residues, from which the most mobile fraction of heavy metals and salts has been removed by carbonation and....../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...

Multi-phase physicochemical modeling of soil-cementitious material interaction

International Nuclear Information System (INIS)

Nakarai, Kenichiro; Ishida, Tetsuya; Maekawa, Koichi

2005-01-01

Multi-phase physicochemical modeling based on thermodynamic approach is studied on gel and capillary pores of nano-micrometers and large voids of micro-millimeters among soil foundation. A computational method about transportation of moisture and ions in pore structure for simulating concrete performance was extended for predicting time-dependent material properties of cemented soil. The proposed model was verified with experimental results of cement hydration, change of relative humidity and leaching of calcium ion from cement hydrate to underground water. (author)

A practical method for estimating maximum shear modulus of cemented sands using unconfined compressive strength

Science.gov (United States)

Choo, Hyunwook; Nam, Hongyeop; Lee, Woojin

2017-12-01

The composition of naturally cemented deposits is very complicated; thus, estimating the maximum shear modulus (Gmax, or shear modulus at very small strains) of cemented sands using the previous empirical formulas is very difficult. The purpose of this experimental investigation is to evaluate the effects of particle size and cement type on the Gmax and unconfined compressive strength (qucs) of cemented sands, with the ultimate goal of estimating Gmax of cemented sands using qucs. Two sands were artificially cemented using Portland cement or gypsum under varying cement contents (2%-9%) and relative densities (30%-80%). Unconfined compression tests and bender element tests were performed, and the results from previous studies of two cemented sands were incorporated in this study. The results of this study demonstrate that the effect of particle size on the qucs and Gmax of four cemented sands is insignificant, and the variation of qucs and Gmax can be captured by the ratio between volume of void and volume of cement. qucs and Gmax of sand cemented with Portland cement are greater than those of sand cemented with gypsum. However, the relationship between qucs and Gmax of the cemented sand is not affected by the void ratio, cement type and cement content, revealing that Gmax of the complex naturally cemented soils with unknown in-situ void ratio, cement type and cement content can be estimated using qucs.

セメント改良された高含水比粘性土の強度特性

OpenAIRE

平川, 修治; 柴田, 徹; 西原, 晃; 稲岡, 政孝; ヒラカワ, シュウジ; シバタ, トオル; ニシハラ, アキラ; イナオカ, マサタカ; Shuji, HIRAKAWA; Toru, SHIBATA; Akira, NISHIHARA; Masataka, INAOKA

2000-01-01

Cement treatment of soils by liquified stabilization is one of effective methods for improving utilization of large mass of surplus soils generated by construction works. In liquified stabilization, water content of soils is so high comparing with conventional stabilization method that water content affects the strength of cement treated soils. In case of cement treatment in clayey soils, effect of the physical and chemical properties of surplus soils cannot be disregarded too. In this resear...

Postprocedural CT for perivertebral cement leakage in percutaneous vertebroplasty is not necessary - results from VERTOS II

International Nuclear Information System (INIS)

Venmans, Alexander; Klazen, Caroline A.; Rooij, Willem Jan van; Lohle, Paul N.; Vries, Jolanda de; Mali, Willem P.

2011-01-01

During percutaneous vertebroplasty (PV), perivertebral cement leakage frequently occurs. There is some concern that cement deposits may migrate towards the lungs via the veins during follow-up. We used baseline and follow-up computed tomography (CT) to assess the incidence and extend of late cement migration in a large consecutive patient cohort. VERTOS II is a prospective multicenter randomized controlled trial comparing PV with conservative therapy for osteoporotic vertebral compression fractures (OVCFs). Patients assigned to PV had baseline postprocedural CT scans of the treated vertebral bodies. After a mean follow-up of 22 months, 54 of 78 patients (69%) had follow-up CT. CT scans were analyzed and compared for perivertebral venous, discal, and soft tissue leakage. Perivertebral cement leakage occurred in 64 of 80 treated vertebrae (80%; 95% CI, 70% to 87%). All patients remained asymptomatic. Perivertebral venous leakage was present in 56 vertebrae (88%), mostly in the anterior external venous plexus (46 of 56, 82%). Discal leakage occurred in 22 of 64 vertebrae (34%) and soft tissue leakage in two of 64 (4%). Mean injected cement volume in vertebrae with leakage was higher (4.5 versus 3.7 cm 3 , p = 0.04). Follow-up CT scan showed unchanged perivertebral cement leakages without late cement migration. Perivertebral cement leaks during PV for OVCFs occurred frequently in the VERTOS II trial. Cement leakage occurred more frequently with higher injected volumes. However, all patients remained asymptomatic, and late cement migration during follow-up did not occur. Standard postprocedural CT of the treated vertebral body in PV is not necessary. (orig.)

Postprocedural CT for perivertebral cement leakage in percutaneous vertebroplasty is not necessary - results from VERTOS II

Energy Technology Data Exchange (ETDEWEB)

Venmans, Alexander; Klazen, Caroline A.; Rooij, Willem Jan van; Lohle, Paul N. [St. Elisabeth Ziekenhuis Tilburg, Department of Radiology, Tilburg (Netherlands); Vries, Jolanda de [St. Elisabeth Ziekenhuis Tilburg, Department of Medical Psychology, Tilburg (Netherlands); Mali, Willem P. [University Medical Centre Utrecht, Department of Radiology, Utrecht (Netherlands)

2011-01-15

During percutaneous vertebroplasty (PV), perivertebral cement leakage frequently occurs. There is some concern that cement deposits may migrate towards the lungs via the veins during follow-up. We used baseline and follow-up computed tomography (CT) to assess the incidence and extend of late cement migration in a large consecutive patient cohort. VERTOS II is a prospective multicenter randomized controlled trial comparing PV with conservative therapy for osteoporotic vertebral compression fractures (OVCFs). Patients assigned to PV had baseline postprocedural CT scans of the treated vertebral bodies. After a mean follow-up of 22 months, 54 of 78 patients (69%) had follow-up CT. CT scans were analyzed and compared for perivertebral venous, discal, and soft tissue leakage. Perivertebral cement leakage occurred in 64 of 80 treated vertebrae (80%; 95% CI, 70% to 87%). All patients remained asymptomatic. Perivertebral venous leakage was present in 56 vertebrae (88%), mostly in the anterior external venous plexus (46 of 56, 82%). Discal leakage occurred in 22 of 64 vertebrae (34%) and soft tissue leakage in two of 64 (4%). Mean injected cement volume in vertebrae with leakage was higher (4.5 versus 3.7 cm{sup 3}, p = 0.04). Follow-up CT scan showed unchanged perivertebral cement leakages without late cement migration. Perivertebral cement leaks during PV for OVCFs occurred frequently in the VERTOS II trial. Cement leakage occurred more frequently with higher injected volumes. However, all patients remained asymptomatic, and late cement migration during follow-up did not occur. Standard postprocedural CT of the treated vertebral body in PV is not necessary. (orig.)

Study on strength estimation of soil cement used in the embedded pile method by electrical resistivity measurement

Science.gov (United States)

Mochida, Y.; Sakurai, Y.; Indra, H.; Karimi, A. L.

2017-11-01

Problems caused by poor quality control and quality assurance of the pre-boring embedded pile construction, such as on domestic apartment house is still occurring nowadays. An adequate consideration for invisible risks inside or below the ground is important in pile foundation construction therefore the demand for advanced and reliable quality assurance is increase in the future. In this research, to understand the quality of the construction at early stage, the compressive strength of cement-soil mixture of pile construction after 28 days is estimated using electrical resistivity value of the mixture. More accurate measurement for electrical resistivity value is conducted by inserting the electrodes without using potassium chloride solution as a catalyst. The result showed that there is a certain tendency in the electric resistivity value at the early age regarding to the type of soil (sand, clay) mixed in. The most accurate estimation was achieved from the electric resistivity value at the first day and several days onwards, and from the compressive strength after 3 days.

A modified PMMA cement (Sub-cement) for accelerated fatigue testing of cemented implant constructs using cadaveric bone.

Science.gov (United States)

Race, Amos; Miller, Mark A; Mann, Kenneth A

2008-10-20

Pre-clinical screening of cemented implant systems could be improved by modeling the longer-term response of the implant/cement/bone construct to cyclic loading. We formulated bone cement with degraded fatigue fracture properties (Sub-cement) such that long-term fatigue could be simulated in short-term cadaver tests. Sub-cement was made by adding a chain-transfer agent to standard polymethylmethacrylate (PMMA) cement. This reduced the molecular weight of the inter-bead matrix without changing reaction-rate or handling characteristics. Static mechanical properties were approximately equivalent to normal cement. Over a physiologically reasonable range of stress-intensity factor, fatigue crack propagation rates for Sub-cement were higher by a factor of 25+/-19. When tested in a simplified 2 1/2-D physical model of a stem-cement-bone system, crack growth from the stem was accelerated by a factor of 100. Sub-cement accelerated both crack initiation and growth rate. Sub-cement is now being evaluated in full stem/cement/femur models.

Dynamics of soil organic carbon and microbial activity in treated wastewater irrigated agricultural soils along soil profiles

Science.gov (United States)

Jüschke, Elisabeth; Marschner, Bernd; Chen, Yona; Tarchitzky, Jorge

2010-05-01

Treated wastewater (TWW) is an important source for irrigation water in arid and semiarid regions and already serves as an important water source in Jordan, the Palestinian Territories and Israel. Reclaimed water still contains organic matter (OM) and various compounds that may effect microbial activity and soil quality (Feigin et al. 1991). Natural soil organic carbon (SOC) may be altered by interactions between these compounds and the soil microorganisms. This study evaluates the effects of TWW irrigation on the quality, dynamics and microbial transformations of natural SOC. Priming effects (PE) and SOC mineralization were determined to estimate the influence of TWW irrigation on SOC along soil profiles of agricultural soils in Israel and the Westbank. The used soil material derived from three different sampling sites allocated in Israel and The Palestinian Authority. Soil samples were taken always from TWW irrigated sites and control fields from 6 different depths (0-10, 10-20, 20-30, 30-50, 50-70, 70-100 cm). Soil carbon content and microbiological parameters (microbial biomass, microbial activities and enzyme activities) were investigated. In several sites, subsoils (50-160 cm) from TWW irrigated plots were depleted in soil organic matter with the largest differences occurring in sites with the longest TWW irrigation history. Laboratory incubation experiments with additions of 14C-labelled compounds to the soils showed that microbial activity in freshwater irrigated soils was much more stimulated by sugars or amino acids than in TWW irrigated soils. The lack of such "priming effects" (Hamer & Marschner 2005) in the TWW irrigated soils indicates that here the microorganisms are already operating at their optimal metabolic activity due to the continuous substrate inputs with soluble organic compounds from the TWW. The fact that PE are triggered continuously due to TWW irrigation may result in a decrease of SOC over long term irrigation. Already now this could be

Corrosion-resistant Foamed Cements for Carbon Steels

Energy Technology Data Exchange (ETDEWEB)

Sugama T.; Gill, S.; Pyatina, T., Muraca, A.; Keese, R.; Khan, A.; Bour, D.

2012-12-01

The cementitious material consisting of Secar #80, Class F fly ash, and sodium silicate designed as an alternative thermal-shock resistant cement for the Enhanced Geothermal System (EGS) wells was treated with cocamidopropyl dimethylamine oxide-based compound as foaming agent (FA) to prepare numerous air bubble-dispersed low density cement slurries of and #61603;1.3 g/cm3. Then, the foamed slurry was modified with acrylic emulsion (AE) as corrosion inhibitor. We detailed the positive effects of the acrylic polymer (AP) in this emulsion on the five different properties of the foamed cement: 1) The hydrothermal stability of the AP in 200 and #61616;C-autoclaved cements; 2) the hydrolysis-hydration reactions of the slurry at 85 and #61616;C; 3) the composition of crystalline phases assembled and the microstructure developed in autoclaved cements; 4) the mechanical behaviors of the autoclaved cements; and, 5) the corrosion mitigation of carbon steel (CS) by the polymer. For the first property, the hydrothermal-catalyzed acid-base interactions between the AP and cement resulted in Ca-or Na-complexed carboxylate derivatives, which led to the improvement of thermal stability of the AP. This interaction also stimulated the cement hydration reactions, enhancing the total heat evolved during cement’s curing. Addition of AP did not alter any of the crystalline phase compositions responsible for the strength of the cement. Furthermore, the AP-modified cement developed the porous microstructure with numerous defect-free cavities of disconnected voids. These effects together contributed to the improvement of compressive-strength and –toughness of the cured cement. AP modification of the cement also offered an improved protection of CS against brine-caused corrosion. There were three major factors governing the corrosion protection: 1) Reducing the extents of infiltration and transportation of corrosive electrolytes through the cement layer deposited on the underlying CS

stabilization of ikpayongo laterite with cement and calcium carbide

African Journals Online (AJOL)

PROF EKWUEME

the stabilization of soil will ensure economy in road construction, while providing an effective way of disposing calcium carbide waste. KEYWORDS: Cement, Calcium carbide waste, Stabilization, Ikpayongo laterite, Pavement material. INTRODUCTION. Road building in the developing nations has been a major challenge to ...

Bone-Cement: The New Medical Quick Fix

Directory of Open Access Journals (Sweden)

Dinesh Bhatia

2010-01-01

Full Text Available

Bone Cement is being widely used in vertebroplasty, a minimally invasive surgical procedure to treat spinal fractures and collapsed vertebrae. It is being labeled as a concrete success in medical field. It is being used to treat fractures due to osteoporosis, menopause, steroids, hyperthyroidism and chronic obstructive pulmonary diseases.  In this technique a needle with bone cement (PMMA, polymethylmethacrylate is injected into the collapsed vertebra after administering local anesthesia to patient. It solidifies within few minutes and provides support to damaged bone resulting in relief to the patient. It also prevents the movement between different parts of the broken bone. Hence it requires a short hospital stay for the patient and the procedure can be performed with much ease and at significant lower costs. Patient can resume normal activity within a day or so. Bone cement is now being referred to as the quick medical fix material for early repair of fractures.

Experimental evaluation of cement materials for solidifying sodium nitrate

International Nuclear Information System (INIS)

Sasaki, Tadashi; Numata, Mamoru; Suzuki, Yasuhiro; Kubo, Yoshikazu

2003-03-01

Low-level liquid waste containing sodium nitrate is planned to be transformed to salt block by evaporation with sodium borate in the Low-level Waste Treatment Facility (LWTF), then salt block will be stored temporally. It should be important to investigate the method how to treat these liquid waste suitable to final disposal criteria that will be settled in future. Cement solidification is one of promising candidates because it has been achieved as the solidification material for the shallow land disposal. The research was conducted to evaluate applicability of various cement materials to solidification of sodium nitrate. The following cements were tested. Ordinary Portland Cement (OPC). Portland Blast-furnace Slag Cement; C type (PBFSC). Alkali Activated Slag Cement (AASC, supplied by JGC). The test results are as follows; (1) AASC is characterized by a high sodium nitrate loading (-70 wt%) compared with other types of cement material. High fluidity of the cement paste, high strength after solidification, and minimization of free water on the cement paste are achieved under all test conditions. (2) OOPC and PBFSC produced free water on the cement paste in the early days and delayed the hardening period. 3 or more days are required to harden evan with 30 wt% content of sodium nitrate. (3) Though PBFSC contains blast furnace slag similar to AASC, there is no advantage prior to OPC. To design an ideal cement conditioning system for sodium nitrate liquid waste in the LWTF, the further studies are necessary such as the simulated waste test, Kd test, pilot test, and layout design. (author)

modified water-cement ratio law for compressive strength of rice

African Journals Online (AJOL)

user

various types of structures due to its structural stability and strength [1]. ... value of water-cement ratio results in greater pore spaces in .... as well as removing the excess water on the surface of the soil particles. ... and aggregate impact value.

Some Remarks on Practical Aspects of Laboratory Testing of Deep Soil Mixing Composites Achieved in Organic Soils

Science.gov (United States)

Kanty, Piotr; Rybak, Jarosław; Stefaniuk, Damian

2017-10-01

This paper presents the results of laboratory testing of organic soil-cement samples are presented in the paper. The research program continues previously reported the authors’ experiences with cement-fly ash-soil sample testing. Over 100 of compression and a dozen of tension tests have been carried out altogether. Several samples were waiting for failure test for over one year after they were formed. Several factors, like: the large amount of the tested samples, a long observation time, carrying out the tests in complex cycles of loading and the possibility of registering the loads and deformation in the axial and lateral direction - have made it possible to take into consideration numerous interdependencies, three of which have been presented in this work: the increments of compression strength, the stiffness of soil-cement in relation to strength and the tensile strength. Compressive strength, elastic modulus and tensile resistance of cubic samples were examined. Samples were mixed and stored in the laboratory conditions. Further numerical analysis in the Finite Element Method numerical code Z_Soil, were performed on the basis of laboratory test results. Computations prove that cement-based stabilization of organic soil brings serious risks (in terms of material capacity and stiffness) and Deep Soil Mixing technology should not be recommended for achieving it. The numerical analysis presented in the study below includes only one type of organic and sandy soil and several possible geometric combinations. Despite that, it clearly points to the fact that designing the DSM columns in the organic soil may be linked with a considerable risk and the settlement may reach too high values. During in situ mixing, the organic material surrounded by sand layers surely mixes with one another in certain areas. However, it has not been examined and it is difficult to assume such mixing already at the designing stage. In case of designing the DSM columns which goes through a

Performance of Cement Containing Laterite as Supplementary Cementing Material

Directory of Open Access Journals (Sweden)

Abbas Bukhari, Z. S.

2013-03-01

Full Text Available The utilization of different industrial waste, by-products or other materials such as ground granulated blast furnace slag, silica fume, fly ash, limestone, and kiln dust, etc. as supplemen- tary cementing materials has received considerable attention in recent years. A study has been conducted to look into the performance of laterite as Supplementary Cementing Materials (SCM. The study focuses on compressive strength performance of blended cement containing different percentage of laterite. The cement is replaced accordingly with percentage of 2 %, 5 %, 7 % and 10 % by weight. In addition, the effect of use of three chemically different laterites have been studied on physical performance of cement as in setting time, Le-Chatlier expansion, loss on ignition, insoluble residue, free lime and specifically compressive strength of cement cubes tested at the age of 3, 7, and 28 days. The results show that the strength of cement blended with laterite as SCM is enhanced. Key words: Portland cement, supplementary cementing materials (SCM, laterite, compressive strength KUI – 6/2013 Received January 4, 2012 Accepted February 11, 2013

Microbially influenced degradation of cement-solidified low-level radioactive waste forms

International Nuclear Information System (INIS)

Rogers, R.D.; Hamilton, M.A.; Veeh, R.H.; McConnell, J.W. Jr.

1996-01-01

Because of its apparent structural integrity, cement has been widely used in the United States as a binder to solidify Class B and C low-level radioactive waste (LLW). However, the resulting cement preparations are susceptible to failure due to the actions of stress and environment. This paper contains information on three groups of microoganisms that are associated with the degradation of cement materials: sulfur-oxidizing bacteria (Thiobacillus), nitrifying bacteria (Nitrosomonas and Nitrobacter), and heterotrophic bacteria, which produce organic acids. Preliminary work using laboratory- and vendor-manufactured, simulated waste forms exposed to thiobacilli has shown that microbiologically influenced degradation has the potential to severely compromise the structural integrity of ion-exchange resin and evaporator-bottoms waste that is solidified with cement. In addition, it was found that a significant percentage of calcium was leached from the treated waste forms. Also, the surface pH of the treated specimens was decreased to below 2. These conditions apparently contributed to the physical deterioration of simulated waste forms after 30 to 60 days of exposure

Leaching tests of cemented organic radioactive waste

International Nuclear Information System (INIS)

Calabria, Jaqueline A. Almeida; Haucz, Maria Judite A.; Tello, Cledola Cassia O.

2011-01-01

The use of radioisotopes in research, medical and industrial activities generates organic liquid radioactive wastes. At Centro de Desenvolvimento da Tecnologia Nuclear (CDTN) are produced organic liquid wastes from different sources, one of these are the solvent extraction activities, whose the waste volume is the largest one. Therefore a research was carried out to treat them. Several techniques to treat organic liquid radioactive wastes have been evaluated, among them incineration, oxidation processes, alkaline hydrolysis, distillation, absorption and cementation. Laboratory experiments were accomplished to establish the most adequate process in order to obtain qualified products for storage and disposal. Absorption followed by cementation was the procedure used in this study, i.e. absorbent substances were added to the organic liquid wastes before mixing with the cement. Initially were defined the absorbers, and evaluated the formulation in relation to the compressive strength of its products. Bentonite from different suppliers (B and G) and vermiculite in two granulometries (M - medium and F - small) were tested. In order to assess the product quality the specimens were submitted to the leaching test according the Standard ISO 6961 and its results were evaluated. Then they were compared with the values established by Standard CNEN NN 6.09 A cceptance criteria for waste products to be disposed , to verify if they meet the requirements for safely storage and disposal. Through this study the best formulations to treat the organic wastes were established. (author)

Effects of compost and phosphate on plant arsenic accumulation from soils near pressure-treated wood

International Nuclear Information System (INIS)

Cao Xinde; Ma, Lena Q.

2004-01-01

Leaching of arsenic (As) from chromated copper arsenate (CCA)-treated wood may elevate soil arsenic levels. Thus, an environmental concern arises regarding accumulation of As in vegetables grown in these soils. In this study, a greenhouse experiment was conducted to evaluate As accumulation by vegetables from the soils adjacent to the CCA-treated utility poles and fences and examine the effects of soil amendments on plant As accumulation. Carrot (Daucus carota L.) and lettuce (Lactuca sativa L.) were grown for ten weeks in the soil with or without compost and phosphate amendments. As expected, elevated As concentrations were observed in the pole soil (43 mg kg -1 ) and in the fence soil (27 mg kg -1 ), resulting in enhanced As accumulation of 44 mg kg -1 in carrot and 32 mg kg -1 in lettuce. Addition of phosphate to soils increased As accumulation by 4.56-9.3 times for carrot and 2.45-10.1 for lettuce due to increased soil water-soluble As via replacement of arsenate by phosphate in soil. However, biosolid compost application significantly reduced plant As uptake by 79-86%, relative to the untreated soils. This suppression is possibly because of As adsorbed by biosolid organic mater, which reduced As phytoavailability. Fractionation analysis showed that biosolid decreased As in soil water-soluble, exchangeable, and carbonate fraction by 45%, whereas phosphate increased it up to 2.61 times, compared to the untreated soils. Our results indicate that growing vegetables in soils near CCA-treated wood may pose a risk of As exposure for humans. Compost amendment can reduce such a risk by reducing As accumulation by vegetables and can be an important strategy for remediating CCA-contaminated soils. Caution should be taken for phosphate application since it enhances As accumulation. - Capsule: Compost amendment can reduce As exposure risk for humans by reducing As accumulation by vegetables and can be an important strategy for remediating CCA-contaminated soils

Effects of compost and phosphate on plant arsenic accumulation from soils near pressure-treated wood

Energy Technology Data Exchange (ETDEWEB)

Cao Xinde [Soil and Water Science Department, University of Florida, Gainesville, FL (United States)]. E-mail: xcao@stevens.edu; Ma, Lena Q. [Soil and Water Science Department, University of Florida, Gainesville, FL (United States)

2004-12-01

Leaching of arsenic (As) from chromated copper arsenate (CCA)-treated wood may elevate soil arsenic levels. Thus, an environmental concern arises regarding accumulation of As in vegetables grown in these soils. In this study, a greenhouse experiment was conducted to evaluate As accumulation by vegetables from the soils adjacent to the CCA-treated utility poles and fences and examine the effects of soil amendments on plant As accumulation. Carrot (Daucus carota L.) and lettuce (Lactuca sativa L.) were grown for ten weeks in the soil with or without compost and phosphate amendments. As expected, elevated As concentrations were observed in the pole soil (43 mg kg{sup -1}) and in the fence soil (27 mg kg{sup -1}), resulting in enhanced As accumulation of 44 mg kg{sup -1} in carrot and 32 mg kg{sup -1} in lettuce. Addition of phosphate to soils increased As accumulation by 4.56-9.3 times for carrot and 2.45-10.1 for lettuce due to increased soil water-soluble As via replacement of arsenate by phosphate in soil. However, biosolid compost application significantly reduced plant As uptake by 79-86%, relative to the untreated soils. This suppression is possibly because of As adsorbed by biosolid organic mater, which reduced As phytoavailability. Fractionation analysis showed that biosolid decreased As in soil water-soluble, exchangeable, and carbonate fraction by 45%, whereas phosphate increased it up to 2.61 times, compared to the untreated soils. Our results indicate that growing vegetables in soils near CCA-treated wood may pose a risk of As exposure for humans. Compost amendment can reduce such a risk by reducing As accumulation by vegetables and can be an important strategy for remediating CCA-contaminated soils. Caution should be taken for phosphate application since it enhances As accumulation. - Capsule: Compost amendment can reduce As exposure risk for humans by reducing As accumulation by vegetables and can be an important strategy for remediating CCA

Treated wastewater irrigation effects on soil hydraulic conductivity and aggregate stability of loamy soils in Israel

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Schacht Karsten

2015-03-01

Full Text Available The use of treated wastewater (TWW for agricultural irrigation becomes increasingly important in water stressed regions like the Middle East for substituting fresh water (FW resources. Due to elevated salt concentrations and organic compounds in TWW this practice has potential adverse effects on soil quality, such as the reduction of hydraulic conductivity (HC and soil aggregate stability (SAS. To assess the impact of TWW irrigation in comparison to FW irrigation on HC, in-situ infiltration measurements using mini disk infiltrometer were deployed in four different long-term experimental orchard test sites in Israel. Topsoil samples (0-10 cm were collected for analyzing SAS and determination of selected soil chemical and physical characteristics.

Admixing dredged marine clay with cement-bentonite for reduction of compressibility

Science.gov (United States)

Rahilman, Nur Nazihah Nur; Chan, Chee-Ming

2017-11-01

Cement-based solidification/stabilization is a method that is widely used for the treatment of dredged marine clay. The key objective for solidification/stabilization is to improve the engineering properties of the originally soft, weak material. Dredged materials are normally low in shear strength and bearing capacity while high incompressibility. In order to improve the material's properties for possible reuse, a study on the one-dimensional compressibility of lightly solidified dredged marine clay admixed with bentonite was conducted. On the other hand, due to the viscous nature, particularly the swelling property, bentonite is a popular volumising agent for backfills. In the present study, standard oedometer test was carried out to examine the compressibility of the treated sample. Complementary strength measurements were also conducted with laboratory vane shear setup on both the untreated and treated dredged marine clay. The results showed that at the same binder content, the addition of bentonite contributed significantly to the reduction of compressibility and rise in undrained shear strength. These improved properties made the otherwise discarded dredged marine soils potentially reusable for reclamation works, for instance.

Performance of mutagen treated Jatropha curcas (Petro-crop) on alkali soil

International Nuclear Information System (INIS)

Pandey, R.K.; Datta, S.K.; Mishra, P.N.

1998-01-01

Under the user land development programme, seeds of Jatropha curcas (Euphorbiaces) were treated with 6, 12, 18 and 24 krad of gamma rays and sown in randomised block design on different grades of alkali soils. Wide range of variability could be detected in mutagen treated population. Results indicate that suitable strains of J. curcas can be isolated through mutation breeding programme for utilisation of user land. (author)

A Novel Composite PMMA-based Bone Cement with Reduced Potential for Thermal Necrosis.

Science.gov (United States)

Lv, Yang; Li, Ailing; Zhou, Fang; Pan, Xiaoyu; Liang, Fuxin; Qu, Xiaozhong; Qiu, Dong; Yang, Zhenzhong

2015-06-03

Percutaneous vertebroplasty (VP) and balloon kyphoplasty (BKP) are now widely used to treat patients who suffer painful vertebral compression fractures. In each of these treatments, a bone cement paste is injected into the fractured vertebral body/bodies, and the cement of choice is a poly(methyl methacrylate) (PMMA) bone cement. One drawback of this cement is the very high exothermic temperature, which, it has been suggested, causes thermal necrosis of surrounding tissue. In the present work, we prepared novel composite PMMA bone cement where microcapsules containing a phase change material (paraffin) (PCMc) were mixed with the powder of the cement. A PCM absorbs generated heat and, as such, its presence in the cement may lead to reduction in thermal necrosis. We determined a number of properties of the composite cement. Compared to the values for a control cement (a commercially available PMMA cement used in VP and BKP), each composite cement was found to have significantly lower maximum exothermic temperature, increased setting time, significantly lower compressive strength, significantly lower compressive modulus, comparable biocompatibility, and significantly smaller thermal necrosis zone. Composite cement containing 20% PCMc may be suitable for use in VP and BKP and thus deserves further evaluation.

Degree of saturation effect on the grout-soil interface shear strength of soil nailing

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Wang Qiong

2016-01-01

Full Text Available In the grouted soil nailing system, the bonding strength of cement grout-soil interface offers the required resistance to maintain the stability of whole structure. In practice, soil nailing applications are often placed at unsaturated conditions, such as soil slopes, shallow foundations, retaining walls and pavement structures. In these cases, the water content in the soil nail zone may increase or decrease due to rain water or dry weather, and even cannot become saturated during their design service life. In this study, the effect of water content (degree of saturation on the shear strength of interface between cement grout and sand are experimentally investigated by means of direct shear test. Meanwhile the water retention curve was determined and interface microstructure was observed. Experimental results show that the shear strength of interface changes non-monotonously with degree of saturation when the interface was prepared, due to the non-monotonousness of the cohesiveness between soil particles. The less the cohesiveness between sand particles, the more grout was observed been penetrated into the voids, and thus the larger the interface shear stress.

Influence of iron-bearing phyllosilicates on the dechlorination kinetics of 1,1,1-trichloroethane in Fe(II)/cement slurries.

Science.gov (United States)

Jung, Bahngmi; Batchelor, Bill

2007-07-01

This study examines the effect of iron-bearing phyllosilicates on dechlorination rates of chlorinated aliphatic hydrocarbons (CAHs) in iron-based degradative solidification/stabilization (DS/S-Fe(II)). Laboratory batch experiments were conducted to evaluate dechlorination rates of 1,1,1-trichloroethane (1,1,1-TCA) in a mixture solution of Fe(II), cement and three different iron-bearing phyllosilicates (biotite, vermiculite, and montmorillonite). A first-order rate model was generally used to describe the dechlorination kinetics and the rate constants were dependent on soil mineral type (biotite, vermiculite, and montmorillonite), Fe(II) dose, and the mass ratio of cement to soil mineral. The pseudo-first-order rate constant for montmorillonite was lower than that for biotite and vermiculite by factors of 11-27 when the mass ratio of cement to phyllosilicates was fixed at one. The presence of biotite and vermiculite increase and the presence of montmorillonite decrease the degradation rate that would be observed in their absence. The effect of cement/mineral ratio on rate constants with three different soil minerals indicates that biotite was more reactive than the other two phyllosilicates. This may be due to high accessible natural Fe(II) content in biotite. Montmorillonite appears to inhibit dechlorination by either inactivating Fe(II) by ion exchange or by physically blocking active sites on cement hydration products.

Freeze-Thaw Performance and Moisture-Induced Damage Resistance of Base Course Stabilized with Slow Setting Bitumen Emulsion-Portland Cement Additives

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Mojtaba Shojaei Baghini

2015-01-01

Full Text Available Freeze-thaw (FT cycles and moisture susceptibility are important factors influencing the geotechnical characteristics of soil-aggregates. Given the lack of published information on the behavior of cement-bitumen emulsion-treated base (CBETB under environmental conditions, especially freezing and thawing, this study investigated the effects of these additives on the CBETB performance. The primary goal was to evaluate the resistance of CBETB to moisture damage by performing FT, Marshall conditioning, and AASHTO T-283 tests and to evaluate the long-term stripping susceptibility of CBETB while also predicting the liquid antistripping additives to assess the mixture’s durability and workability. Specimens were stabilized with Portland cement (0%–6%, bitumen emulsion (0%–5%, and Portland cement-bitumen emulsion mixtures and cured for 7 days, and their short- and long-term performances were studied. Evaluation results of both the Marshall stability ratio and the tensile strength ratio show that the additions of additives increase the resistance of the mixtures to moisture damage. Results of durability tests performed for determining the resistance of compacted specimens to repeated FT cycles indicate that the specimen with the 4% cement-3% bitumen emulsion mixture significantly improves water absorption, volume changes, and weight losses. This indicates the effectiveness of this additive as a road base stabilizer with excellent engineering properties for cold regions.

Performances of hydrated cement treated crushed rock base for Western Australian roads

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Suphat Chummuneerat

2014-12-01

Full Text Available The resilient modulus (RM of hydrated cement treated crushed rock base (HCTCRB affected by amount of hydration periods, compaction and dryback processes was presented using repeated load triaxial tests. The related trends of RM corresponding to the different hydration periods still cannot be concluded. Instead, It is found that the moisture content plays more major influence on the RM performance. Higher additional water during compaction of HCTCRB, even at its optimum moisture content and induced higher dry density, led to the inferior RM performance compared to the sample without water addition. The RM of damper samples can be improved through dryback process and superior to that of the sample without water addition at the same moisture content. However, the samples without water addition during compaction deliver the comparable RM values even its dry density is lower than the other two types. These results indicate the significant influence of moisture content to the performances of HCTCRB with regardless of the dry density. Finally, the experimental results of HCTCRB and parent material are evaluated with the K-θ model and the model recommended by Austroads. These two models provide the excellent fit of the tested results with high degree of determination.

Risk assessment applications for determining cleanup limits for uranium in treated and untreated soils

International Nuclear Information System (INIS)

Armstrong, A.Q.; Layton, D.W.; Rutz, E.E.

1994-01-01

Uranium-contaminated soils are present at various locations across the US where uranium was processed for nuclear fuels or atomic weapons. Important issues relative to such contamination include the assessment of potential health risks associated with human exposures to the residual uranium and the determination of safe levels of uranium in soils that have been treated by a given technology. This paper discusses various risk assessment considerations that must be dealt with when developing cleanup limits for uranium in treated and untreated soils. Key issues addressed include alternative land use scenarios, potential exposure pathways, characterization of the bioavailability of uranium compounds in food and water, a brief overview of health risks associated with uranium and its daughter products as well as a summary of considerations for development of risk-based cleanup limits for uranium in soils

Method of treatment of radioactive silts and soils

International Nuclear Information System (INIS)

Varlakov, A.P.; Sobolev, I.A.; Barinov, A.S.; Dmitriev, S.A.; Karlin, S.V.; Flit, V.U.

1997-01-01

To solve the problem of silts and soils that are contaminated with radioactive and toxic substances, the following method has been developed at SIA RADON. The material is mixed with limestone and other components, including up to 70% (mass) of dried residue of liquid radioactive waste. The mixture is heated at 800 to 1,000 C, shredded, and used to form cement. This cementation process may be used to treat radioactive or other chemical waste. The work demonstrated that in the case of silts, for example, the product volume is reduced by a factor of 1.5 to 3 compared to the initial silts volume. A fast hardening, durable product is obtained, the quality of which is not inferior to that obtained by using the traditional binders. For some parameters, e.g., hardening rate and macroelement leaching, the current method is significantly better than the traditional cementation process. It has also been demonstrated that, over a wide range of parameters, when dry residue of liquid radioactive waste is used in the initial mixture, the part of NO x can be reduced to nitrogen, thereby reducing NO x emissions

Influence of lead on stabilization/solidification by ordinary Portland cement and magnesium phosphate cement.

Science.gov (United States)

Wang, Yan-Shuai; Dai, Jian-Guo; Wang, Lei; Tsang, Daniel C W; Poon, Chi Sun

2018-01-01

Inorganic binder-based stabilization/solidification (S/S) of Pb-contaminated soil is a commonly used remediation approach. This paper investigates the influences of soluble Pb species on the hydration process of two types of inorganic binders: ordinary Portland cement (OPC) and magnesium potassium phosphate cement (MKPC). The environmental leachability, compressive strength, and setting time of the cement products are assessed as the primary performance indicators. The mechanisms of Pb involved in the hydration process are analyzed through X-ray diffraction (XRD), hydration heat evolution, and thermogravimetric analyses. Results show that the presence of Pb imposes adverse impact on the compressive strength (decreased by 30.4%) and the final setting time (prolonged by 334.7%) of OPC, but it exerts much less influence on those of MKPC. The reduced strength and delayed setting are attributed to the retarded hydration reaction rate of OPC during the induction period. These results suggest that the OPC-based S/S of soluble Pb mainly depends on physical encapsulation by calcium-silicate-hydrate (CSH) gels. In contrast, in case of MKPC-based S/S process, chemical stabilization with residual phosphate (pyromorphite and lead phosphate precipitation) and physical fixation of cementitious struvite-K are the major mechanisms. Therefore, MKPC is a more efficient and chemically stable inorganic binder for the Pb S/S process. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of cement on the stability and the wearrance of soils in earthworks

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Karam Feth-Allah Bendimerad

2018-01-01

Full Text Available The technique of soil treatment is known for a long time, currently, during the big motorway programs this technique is experiencing important to reach zero imprints and zero deposit in a context of sustainable development or the socio-economic and environmental challenges incite during the work of earthworks. Our work puts highlights the treatment of fine soils in westerns region of Algeria (wilaya of Tlemcen, a project to construct a payment station for the entry of the wilaya (sample n°1, electrical post 400/200 KVA in the locality Ain Fetah (sample n°2, belonging to the class A3h (very plastic clay according to the Technical Guide for Earthworks (GTR, whose use in the raw state would involve great risks of stability because of their plasticity (Ip > 20% and their low capacity (CBR < 25 according to the Specification of the Algerian Loads, Technical Clauses (CSDCA-CT by the incorporation of the stabilizing agents, for example the variant of locally manufactured CEM II / A42.5N composite cement, in order to define their behaviours by examining the variation of their characteristics determined according to the Algerian standards and at a ambient temperature according to the additive dosage and to contribute to the deduction of the interest of the method demonstrated previously. The results obtained clearly show a tendency the rearrange classification of the soils studied according to the unified system en proportion whit to the additive dosage (0 to 14% in view of the appreciable change in the plasticity behaviour, which results in a decrease in the plasticity index, going up to 37.7% and the 11% of the maximum dry density accompanied by a satisfactory increase in the suitability of the materials to be supported a load with different moisture content and changes in water regime exceeds 100%. Given the unavailability of other exploitable deposits near the site and the experimental results obtained, the variant of the treatment seems feasible.

Development of road soil cement compositions modified with complex additive based on polycarboxylic ether

Science.gov (United States)

Bulanov, P. E.; Vdovin, E. A.; Mavliev, L. F.; Kuznetsov, D. A.

2018-03-01

The paper is focused on the research results of the main physical and technical properties of the cement-stabilized polymineral clay modified with a complex hydrophobic plasticizer based on polycarboxylate and octyltriethoxysilane ethers. A graphical result interpretation of the mathematic model which shows the influence of the complex hydrophobic plasticizer components on the cement-stabilized polymineral clay, containing more than 85% of relict minerals, has been designed. The research significance for the building sector lies in the fact that applying a complex hydrophobic plasticizer provides increasing the compressive strength of the cement-stabilized polymineral clay up to 102%, the tensile bending strength – up to 88%, the freeze-thaw resistance – up to 114%.

Chemical stabilization of subgrade soil for the strategic expeditionary landing field

Science.gov (United States)

Conaway, M. H.

1983-06-01

The Strategic Expeditionary Landing Field (SELF) is a military expeditionary-type airfield with an aluminum matted surface that is designed for sustained tactical and cargo airlift operations in an amphibious objective area. Because of the operational traffic parameters such as loads of the various types of aircraft, tire pressures and volume of traffic, a base layer must be constructed over subgrade soil support conditions which may be only marginal. The base layer could be constructed with conventional soil construction techniques (compaction) and yield the required strength. It would be difficult, however, to maintain this strength for the required one-year service life under many climatic conditions due to the degrading effects of water on the support capacity of many soils. Chemical soil stabilization with lime, portland cement and asphalt stabilizing agents could be used to treat the soil. These additives, when properly mixed with certain types of soils, initiate reactions which will increase soil support strength and enhance durability (resistance to the degrading effects of water). Technically, this procedure is quite viable but logistically, it may not be feasible.

Chemical properties of a Haplustalf soil under irrigation with treated wastewater and nitrogen fertilization

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Leda V. B. D. Silva

2016-04-01

Full Text Available ABSTRACT The objective of this research was to investigate the effects of irrigation with treated wastewater and nitrogen (N fertilization on the chemical characteristics of a Haplustalf soil cultivated with cotton. An experiment was conducted in a greenhouse in a completely randomized design with four replicates, and arranged in a 5 x 4 factorial. Five doses of N fertilization (0, 45, 90, 135 and 180 kg ha-1 and four sources of irrigation water (freshwater, wastewater treated by an anaerobic reactor, wastewater treated by an anaerobic reactor and post-treated by intermittent sand filter in series, wastewater treated in a septic tank and post-treated by an intermittent sand filter were tested. Irrigation was daily performed from July 2011 to January 2012 according to the water demand of cotton resulting in a water depth of 620 mm. It was found that, compared with the conventional management with freshwater irrigation, treated wastewater provides greater accumulation of micronutrient, potassium and sodium in the soil, increasing the risk of sodification in irrigated areas.

ULTRA-LIGHTWEIGHT CEMENT

International Nuclear Information System (INIS)

Fred Sabins

2001-01-01

The objective of this project is to develop an improved ultra-lightweight cement using ultralight hollow glass spheres (ULHS). Work reported herein addresses Task 1: Assess Ultra-Lightweight Cementing Problems and Task 3: Test Ultra-Lightweight Cements. Results reported this quarter include a review and summary of Halliburton Energy Services (HES) and BJ Services historical performance data for lightweight cement applications. These data are analyzed and compared to ULHS cement and foamed cement performances. Similar data is expected from Schlumberger, and an analysis of this data will be completed in the following phases of the project. Quality control testing of materials used to formulate ULHS cements in the laboratory was completed to establish baseline material performance standards. A testing protocol was developed employing standard procedures as well as procedures tailored to evaluate ULHS and foamed cement. This protocol is presented and discussed. Results of further testing of ULHS cements are presented along with an analysis to establish cement performance design criteria to be used during the remainder of the project. Finally, a list of relevant literature on lightweight cement performance is compiled for review during the next quarter

Suitability of alumina cements for the cementation of boreholes under corrosive conditions, especially at the press fitting of CO{sub 2}; Eignung von Tonerdezementen fuer die Bohrlochzementierung unter korrosiven Bedingungen, insbesondere bei CO{sub 2}-Einpressung. Literaturstudie

Energy Technology Data Exchange (ETDEWEB)

Plank, J.; Sieber, R. (comps.) [Technische Univ. Muenchen (Germany). Lehrstuhl fuer Bauchemie

2011-07-15

Calcium aluminate cements, also called aluminate cements, are special cements based on calcium aluminates. In construction (especially in dry-mix mortars), they are valued for their remarkably higher acid and corrosion resistance compared to Portland cement. Their high temperature resistance especially qualifies them for refractory cements which are used e.g. as liners in cement rotary kilns. The worldwide production of calcium aluminate cements adds up to about 3 million tons. In oil well cementing, calcium aluminate cements have first been used at the beginning of the 90ies, in fact initially for geothermal wells. Applications in permafrost soils as well as fire-flooding wells came later. The reason for the use in geothermal wells. Applications in permafrost soils as well as fire-flooding wells came later. The reason for the use in geothermal wells were severe problems with API Portland cements affected by hot, carbonic acid rich formation brines. With support from the companies Unocal and Halliburton, the Brookhaven National Laboratory (USA) developed a special cement based on 60 parts by weight of calcium aluminate cement and 40 parts ASTM class F fly ash. This binder is notably CO{sub 2} resistant when mixed with a 25 wt.% Na-polyphosphate solution. Laboratory tests and field applications conclude that this cement is resistant to CO{sub 2} corrosion at temperatures up to 300 C for over 20 years. In 1997, for the first time numerous geothermal wells have been cemented using this cement. They are intact to this day. When this cement hardens at room temperature, amorphous reaction products are formed and the reaction is incomplete. However, at higher temperatures hydroxyapatite, boehmite, Na-P-zeolite, analcime or katoite are formed as crystalline reaction products. The CO{sub 2} resistance of this cement is due to specific chemical reactions. In contact with hot alkaline carbonate solutions, analcime converts to cancrinite, and CO{sub 2} is incorporated into

Cement-latex grouting mortar for cementing boreholes

Energy Technology Data Exchange (ETDEWEB)

Kateev, I S; Golyshkina, L A; Gorbunova, I V; Kurochkin, B M; Vakula, Ya V

1980-01-01

The need for the development of cement-latex grouting mortar for the purpose of separating strata when reinforcing boreholes at deposits in the Tatar Associated SSR is evaluated. Results of studies of the physical and mechanical properties of cement-latex grouting mortar systems (mortar plus brick) are presented. Formulas for preparing cement-latex grouting mortor are evaluated and results of industrial tests of such mortars shown.

Integrating Electrokinetic and Bioremediation Process for Treating Oil Contaminated Low Permeability Soil

Science.gov (United States)

Ramadan, Bimastyaji Surya; Effendi, Agus Jatnika; Helmy, Qomarudin

2018-02-01

Traditional oil mining activities always ignores environmental regulation which may cause contamination in soil and environment. Crude oil contamination in low-permeability soil complicates recovery process because it requires substantial energy for excavating and crushing the soil. Electrokinetic technology can be used as an alternative technology to treat contaminated soil and improve bioremediation process (biostimulation) through transfer of ions and nutrient that support microorganism growth. This study was conducted using a combination of electrokinetic and bioremediation processes. Result shows that the application of electrokinetic and bioremediation in low permeability soils can provide hydrocarbon removal efficiency up to 46,3% in 7 days operation. The highest amount of microorganism can be found in 3-days operation, which is 2x108 CFU/ml using surfactant as flushing fluid for solubilizing hydrocarbon molecules. Enhancing bioremediation using electrokinetic process is very potential to recover oil contaminated low permeability soil in the future.

Accelerated pavement testing of thin RCC over soil cement pavements

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Zhong Wu

2016-05-01

Full Text Available Three full-scale roller compacted concrete (RCC pavement sections built over a soil cement base were tested under accelerated pavement testing (APT. The RCC thicknesses varied from 102 mm (4 in. to 152 mm (6 in. and to 203 mm (8 in., respectively. A bi-directional loading device with a dual-tire load assembly was used for this experiment. Each test section was instrumented with multiple pressure cells and strain gages. The objective was to evaluate the structural performance and load carrying capacity of thin RCC-surfaced pavements under accelerated loading. The APT results generally indicated that all three RCC pavement sections tested in this study possessed very high load carrying capacity; an estimated pavement life in terms of equivalent single axle load (ESAL for the thinnest RCC section (i.e., RCC thickness of 102 mm evaluated was approximately 19.2 million. It was observed that a fatigue failure would be the primary pavement distress type for a thin RCC pavement under trafficking. Specifically, the development of fatigue cracking was found to originate from a longitudinal crack at the edge or in the center of a tire print, then extended and propagated, and eventually merged with cracks of other directions. Instrumentation results were used to characterize the fatigue damage under different load magnitudes. Finally, based on the APT performance of this experiment, two fatigue models for predicting the fatigue life of thin RCC pavements were developed. Keywords: Roller compacted concrete, APT, Pavement performance, Non-destructive testing, Fatigue analysis

Study on Cr(VI) Leaching from Cement and Cement Composites

Science.gov (United States)

Palascakova, Lenka; Kanuchova, Maria

2018-01-01

This paper reports an experimental study on hexavalent chromium leaching from cement samples and cement composites containing silica fume and zeolite additions that were subjected to various leaching agents. The water-soluble Cr(VI) concentrations in cements ranged from 0.2 to 3.2 mg/kg and represented only 1.8% of the total chromium content. The presence of chromium compounds with both chromium oxidation states of III and VI was detected in the cement samples by X-ray photoelectron spectroscopy (XPS). Leaching tests were performed in a Britton-Robinson buffer to simulate natural conditions and showed increased dissolution of Cr(VI) up to 6 mg/kg. The highest amount of leached hexavalent chromium was detected after leaching in HCl. The findings revealed that the leaching of chromium from cements was higher by 55–80% than that from the cement composites. A minimum concentration was observed for all cement samples when studying the relationship between the soluble Cr(VI) and the cement storage time. PMID:29690550

Potential exposure to clothianidin and risk assessment of manual users of treated soil.

Science.gov (United States)

Ren, JingXia; Tao, ChuanJiang; Zhang, LiYing; Ning, Jun; Mei, XiangDong; She, DongMei

2017-09-01

Treated soil is the second most prevalent application technique for all registered pesticides in China. Some developing countries also adopt this method. However, the safety of this scenario has not been reported in the literature. Experiments were therefore conducted to assess exposure using standard whole-body dosimetry and air sampling methodologies. Dermal deposition was the main route of exposure in this scenario. The total dermal unit exposure (UE) of operators to clothianidin-treated soil was 51.7 mg kg -1 AI handled (SD = 20.59, n = 16), and hands accounted for 36%. Inhalation UE was 0.04 mg kg -1 AI handled (SD = 0.02, n = 4), negligible compared with dermal exposure. Using an NOAEL (no observed adverse effect level) of 10 mg kg -1 day -1 , the margin of exposure was 773, i.e. greater than 100. For the first time, the scenario of treated soil exposure was assessed and was found to pose less risk than conventional pesticide application. These results can be used as a reference in pesticide management. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Leaching of Contamination from Stabilization/Solidification Remediated Soils of Different Texture

Science.gov (United States)

Burlakovs, Juris; Kasparinskis, Raimonds; Klavins, Maris

2012-09-01

Development of soil and groundwater remediation technologies is a matter of great importance to eliminate historically and currently contaminated sites. Stabilization/solidification (S/S) refers to binding of waste contaminants to a more chemically stable form and thus diminishing leaching of contamination. It can be performed using cement with or without additives in order to stabilize and solidify soil with the contamination in matrix. A series of experiments were done to determine leaching properties of spiked soils of different texture bound with cement. Results of experiments showed, that soil texture (content of sand, silt and clay particles) affects the leaching of heavy metals from stabilized soils.

Cement-in-cement acetabular revision with a constrained tripolar component.

Science.gov (United States)

Leonidou, Andreas; Pagkalos, Joseph; Luscombe, Jonathan

2012-02-17

Dislocation of a total hip replacement (THR) is common following total hip arthroplasty (THA). When nonoperative management fails to maintain reduction, revision surgery is considered. The use of constrained acetabular liners has been extensively described. Complete removal of the old cement mantle during revision THA can be challenging and is associated with significant complications. Cement-in-cement revision is an established technique. However, the available clinical and experimental studies focus on femoral stem revision. The purpose of this study was to present a case of cement-in-cement acetabular revision with a constrained component for recurrent dislocations and to investigate the current best evidence for this technique. This article describes the case of a 74-year-old woman who underwent revision of a Charnley THR for recurrent low-energy dislocations. A tripolar constrained acetabular component was cemented over the primary cement mantle following removal of the original liner by reaming, roughening the surface, and thoroughly irrigating and drying the primary cement. Clinical and radiological results were good, with the Oxford Hip Score improving from 11 preoperatively to 24 at 6 months postoperatively. The good short-term results of this case and the current clinical and biomechanical data encourage the use of the cement-in-cement technique for acetabular revision. Careful irrigation, drying, and roughening of the primary surface are necessary. Copyright 2012, SLACK Incorporated.

Ureic nitrogen transformation in multi-layer soil columns treated with urease and nitrification inhibitors.

Science.gov (United States)

Giovannini, Camilla; Garcia-Mina, Josè M; Ciavatta, Claudio; Marzadori, Claudio

2009-06-10

The use of N-(n-butyl)thiophosphoric triamide (NBPT), as a urease inhibitor, is one of the most successful strategies utilized to increase the efficiency of urea-based fertilization. To date, NBPT has been added to the soil incorporated in fertilizers containing either urea or the inhibitor at a fixed percentage on the urea weight. The possibility of using NBPT physically separated from urea-based fertilizers could make its use more flexible. In particular, a granulated product containing NBPT could be utilized in soils treated with different urea-based fertilizers including livestock urine, the amount depending on soil characteristics and/or the urea source (e.g., mineral fertilizer, organo-mineral fertilizer, or animal slurry). In this study, a multilayer soil column device was used to investigate the influence of an experimental granular product (RV) containing NBPT and a garlic extract, combining the ability to protect NBPT by oxidation and nitrification inhibition activity, on (a) spatial variability of soil urease and nitrification activities and (b) timing of urea hydrolysis and mineral-N form accumulation (NO(2)(-), NO(3)(-), NH(4)(+)) in soil treated with urea. The results clearly demonstrated that RV can, effectively, inhibit the soil urease activity along the soil column profile up to 8-10 cm soil layer depth and that the inhibition power of RV was dependent on time and soil depth. However, nitrification activity is not significantly influenced by RV addition. In addition, the soil N transformations were clearly affected by RV; in fact, RV retarded urea hydrolysis and reduced the accumulation of NH(4)(+)-N and NO(2)(-)-N ions along the soil profile. The RV product was demonstrated to be an innovative additive able to modify some key ureic N trasformation processes correlated with the efficiency of the urea-based fertilization, in a soil column higher than 10 cm.

ULTRA-LIGHTWEIGHT CEMENT

International Nuclear Information System (INIS)

Fred Sabins

2001-01-01

The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). Work reported herein addresses Task 1: Assess Ultra-Lightweight Cementing Issues, Task 2: Review Russian Ultra-Lightweight Cement Literature, Task 3: Test Ultra-Lightweight Cements, and Task 8: Develop Field ULHS Cement Blending and Mixing Techniques. Results reported this quarter include: preliminary findings from a literature review focusing on problems associated with ultra-lightweight cements; summary of pertinent information from Russian ultra-lightweight cement literature review; laboratory tests comparing ULHS slurries to foamed slurries and sodium silicate slurries for two different applications; and initial laboratory studies with ULHS in preparation for a field job

Características físicas e mecânicas de misturas de solo, cimento e cinzas de bagaço de cana-de-açúcar Physical and mechanical characteristics of soil-cement-bagasse ash mixtures

Directory of Open Access Journals (Sweden)

Martha Del C. Mesa Valenciano

2004-12-01

Full Text Available Este trabalho teve por finalidade analisar algumas características de misturas de solo, cimento e cinzas de bagaço de cana-de-açúcar para sua possível utilização na fabricação de materiais alternativos de construção. Para tal, amostras de cinzas de bagaço de cana-de-açúcar foram submetidas a um tratamento prévio que consistia de peneiramento e moagem, antes de serem incorporadas às misturas de solo e cimento. Diferentes combinações de cimento-cinzas foram estudadas, determinando-se, para cada uma delas, a consistência normal e a resistência à compressão simples, aos 7 e 28 dias. Posteriormente, corpos-de-prova moldados com tais misturas de solo-cimento-cinzas foram submetidos a ensaios de compactação, compressão simples e absorção de água. Os resultados indicaram a possibilidade de substituir até 20% do cimento Portland, na mistura, por cinzas de bagaço de cana-de-açúcar, sem prejuízo da resistência à compressão simples.This work was done with the objective of studying some physical and mechanical characteristics of the sugarcane bagasse ash added to a soil-cement mixture, in order to obtain an alternative construction material. The sugarcane bagasse ash pre-treatment included both sieving and grinding, before mixing with soil and cement. Different proportions of cement-ash were tested by determining its standard consistence and its compressive resistance at 7 and 28 days age. The various treatments were subsequently applied to the specimens molded with different soil-cement-ash mixtures which in turns were submitted to compaction, unconfined compression and water absorption laboratory tests. The results showed that it is possible to replace up to 20% of Portland cement by sugarcane bagasse ash without any damage to the mixture's compressive strength.

Integrating Electrokinetic and Bioremediation Process for Treating Oil Contaminated Low Permeability Soil

Directory of Open Access Journals (Sweden)

Surya Ramadan Bimastyaji

2018-01-01

Full Text Available Traditional oil mining activities always ignores environmental regulation which may cause contamination in soil and environment. Crude oil contamination in low-permeability soil complicates recovery process because it requires substantial energy for excavating and crushing the soil. Electrokinetic technology can be used as an alternative technology to treat contaminated soil and improve bioremediation process (biostimulation through transfer of ions and nutrient that support microorganism growth. This study was conducted using a combination of electrokinetic and bioremediation processes. Result shows that the application of electrokinetic and bioremediation in low permeability soils can provide hydrocarbon removal efficiency up to 46,3% in 7 days operation. The highest amount of microorganism can be found in 3-days operation, which is 2x108 CFU/ml using surfactant as flushing fluid for solubilizing hydrocarbon molecules. Enhancing bioremediation using electrokinetic process is very potential to recover oil contaminated low permeability soil in the future.

Cement Formation

DEFF Research Database (Denmark)

Telschow, Samira; Jappe Frandsen, Flemming; Theisen, Kirsten

2012-01-01

Cement production has been subject to several technological changes, each of which requires detailed knowledge about the high multiplicity of processes, especially the high temperature process involved in the rotary kiln. This article gives an introduction to the topic of cement, including...... an overview of cement production, selected cement properties, and clinker phase relations. An extended summary of laboratory-scale investigations on clinkerization reactions, the most important reactions in cement production, is provided. Clinker formations by solid state reactions, solid−liquid and liquid......−liquid reactions are discussed, as are the influences of particles sizes on clinker phase formation. Furthermore, a mechanism for clinker phase formation in an industrial rotary kiln reactor is outlined....

Identification and stabilization methods for problematic silt soils : a laboratory evaluation of modification and stabilization additives.

Science.gov (United States)

2003-07-01

The instability and pumping response of non-plastic, high silt (and fine sand) soils was investigated. Common reagents, i.e., lime, lime-fly ash, Portland cement, and slag cement were included as admixtures with three high silt (and fine sand) soils....

Mixture optimization of cement treated demolition waste with recycled masonry and concrete

NARCIS (Netherlands)

Xuan, D.X.; Houben, L.J.M.; Molenaar, A.A.A.; Shui, Z.H,

2011-01-01

Due to environmental reasons and the shortage of natural resources, it is greatly valuable to recycle construction and demolition waste (CDW) as much as possible. One of effective ways to reuse more CDW is to produce a cemented road base material. The recycled CDW however is a mix of recycled

Conceptual Modeling of the Influence of Wetting and Drying Cycles on Soil Aggregation and Stabilization

Science.gov (United States)

Albalasmeh, A. A.; Ghezzehei, T.

2011-12-01

Soil structure directly determines important soil physical properties including porosity, hydraulic conductivity, water retention, and mechanical strength and indirectly influences most biological and chemical processes that occur in and around soil. The interaction of environmental and biotic agents influences the physical condition of the soil, particularly through soil structural evolution. Wetting and drying cycles are important environmental processes known to enhance aggregation, while clay minerals, sesquioxides and soil organic matter (SOM) are the soil solids most involved in soil structural development. We hypothesize that drying of capillary water transports suspended and/or dissolved cementing agents toward inter-particle contacts and eventually deposits part of the colloidal mass forming inter-particle bonds. Here, we will show the role of wetting and drying cycles on soil aggregation and stabilization and how these cycles transport and deposit organic cementing agents at the inter-particle contact. We will present results of the effect of particle size, number of wetting and drying cycles, viscosity, molecule length and concentration of suspended and/or dissolved cementing agents on soil aggregation and stabilization.

CLAY SOIL STABILISATION USING POWDERED GLASS

Directory of Open Access Journals (Sweden)

J. OLUFOWOBI

2014-10-01

Full Text Available This paper assesses the stabilizing effect of powdered glass on clay soil. Broken waste glass was collected and ground into powder form suitable for addition to the clay soil in varying proportions namely 1%, 2%, 5%, 10% and 15% along with 15% cement (base by weight of the soil sample throughout. Consequently, the moisture content, specific gravity, particle size distribution and Atterberg limits tests were carried out to classify the soil using the ASSHTO classification system. Based on the results, the soil sample obtained corresponded to Group A-6 soils identified as ‘fair to poor’ soil type in terms of use as drainage and subgrade material. This justified stabilisation of the soil. Thereafter, compaction, California bearing ratio (CBR and direct shear tests were carried out on the soil with and without the addition of the powdered glass. The results showed improvement in the maximum dry density values on addition of the powdered glass and with corresponding gradual increase up to 5% glass powder content after which it started to decrease at 10% and 15% powdered glass content. The highest CBR values of 14.90% and 112.91% were obtained at 5% glass powder content and 5mm penetration for both the unsoaked and soaked treated samples respectively. The maximum cohesion and angle of internal friction values of 17.0 and 15.0 respectively were obtained at 10% glass powder content.

Salinity effect of irrigation with treated wastewater in basal soil respiration in SE of Spain

Science.gov (United States)

Morugan, A.; Garcia-Orenes, F.; Mataix-Solera, J.

2012-04-01

The use of treated wastewater for the irrigation of agricultural soils is an alternative to utilizing better-quality water, especially in semiarid regions where water shortage is a very serious problem. Wastewater use in agriculture is not a new practice, all over the world this reuse has been common practice for a long time, but the concept is of greater importance currently because of the global water crisis. Replacement of freshwater by treated wastewater is seen as an important conservation strategy contributing to agricultural production, substantial benefits can derive from using this nutrient-rich waste water but there can also be a negative impact. For this reason it is necessary to know precisely the composition of water before applying it to the soil in order to guarantee minimal impact in terms of contamination and salinization. In this work we have been studying, for more than three years, different parameters in calcareous soils irrigated with treated wastewater in an agricultural Mediterranean area located at Biar (Alicante, SE Spain), with a crop of grape (Vitis labrusca). Three types of waters were used for the irrigation of the soil: fresh water (control) (TC), and treated wastewater from secondary (T2) and tertiary treatment (T3). Three different doses of irrigation have been applied to fit the efficiency of the irrigation to the crop and soil type during the study period. A soil sampling was carried out every four months. We show the results of the evolution of basal soil respiration (BSR), and its relationship with other parameters. We observed a similar pattern of behavior for BSR between treatments, a decrease at the first eighteen months of irrigation and an increase at the end of study. In our study case, the variations of BSR obtained for all the treatments seem to be closely related to the dose and frequency of irrigation and the related soil wetting and drying cycles. However, the results showed a negative correlation between BSR and

experimental characterization of clay soils behavior stabilized

African Journals Online (AJOL)

S. Rehab Bekkouche, G. Boukhatem

2016-09-01

Sep 1, 2016 ... California Bearing Ratio (CBR) ... the globe. Clay soils have the curious property of seeing their consistency changes according ... The use of building materials had been popularly applied to soil stabilization, such as cement.

A Twofold Comparison between Dual Cure Resin Modified Cement and Glass Ionomer Cement for Orthodontic Band Cementation.

Science.gov (United States)

Attar, Hanaa El; Elhiny, Omnia; Salem, Ghada; Abdelrahman, Ahmed; Attia, Mazen

2016-12-15

To test the solubility of dual cure resin modified resin cement in a food simulating solution and the shear bond strength compared to conventional Glass ionomer cement. The materials tested were self-adhesive dual cure resin modified cement and Glass Ionomer (GIC). Twenty Teflon moulds were divided into two groups of tens. The first group was injected and packed with the modified resin cement, the second group was packed with GIC. To test the solubility, each mould was weighed before and after being placed in an analytical reagent for 30 days. The solubility was measured as the difference between the initial and final drying mass. To measure the Shear bond strength, 20 freshly extracted wisdom teeth were equally divided into two groups and embedded in self-cure acrylic resin. Four mm sections of stainless steel bands were cemented to the exposed buccal surfaces of teeth under a constant load of 500 g. Shear bond strength was measured using a computer controlled materials testing machine and the load required to deband the samples was recorded in Newtons. GIC showed significantly higher mean weight loss and an insignificant lower Shear bond strength, compared to dual cure resin Cement. It was found that dual cure resin modified cement was less soluble than glass ionomer cement and of comparable bond strength rendering it more useful clinically for orthodontic band cementation.

PURIFIED WASTE FCC CATALYST AS A CEMENT REPLACEMENT MATERIAL

Directory of Open Access Journals (Sweden)

Danute Vaiciukyniene

2015-06-01

Full Text Available Zeolites are commonly used in the fluid catalytic cracking process. Zeolite polluted with oil products and became waste after some time used. The quantity of this waste inevitably rises by expanding rapidly oil industry. The composition of these catalysts depends on the manufacturer and on the process that is going to be used. The main factors retarding hydration process of cement systems and modifying them strength are organic compounds impurities in the waste FCC catalyst. The present paper shows the results of using purified waste FCC catalyst (pFCC from Lithuania oil refinery, as Portland cement replacement material. For this purpose, the purification of waste FCC catalyst (FCC samples was treated with hydrogen peroxide. Hydrogen peroxide (H2O2 is one of the most powerful oxidizers known. By acting of waste with H2O2 it can eliminate the aforementioned waste deficiency, and the obtained product becomes one of the most promising ingredients, in new advanced building materials. Hardened cement paste samples with FCC or pFCC were formed. It was observed that the pFCC blended cements developed higher strength, after 28 days, compared to the samples with FCC or reference samples. Typical content of Portland cement substituting does not exceed 30 % of mass of Portland cement in samples. Reducing the consumption of Portland cement with utilizing waste materials is preferred for reasons of environmental protection.

The mechanical effect of the existing cement mantle on the in-cement femoral revision.

LENUS (Irish Health Repository)

Keeling, Parnell

2012-08-01

Cement-in-cement revision hip arthroplasty is an increasingly popular technique to replace a loose femoral stem which retains much of the original cement mantle. However, some concern exists regarding the retention of the existing fatigued and aged cement in such cement-in-cement revisions. This study investigates whether leaving an existing fatigued and aged cement mantle degrades the mechanical performance of a cement-in-cement revision construct.

Disposal of historically contaminated soil in the cement industry and the evaluation of environmental performance.

Science.gov (United States)

Li, Yeqing; Zhang, Jiang; Miao, Wenjuan; Wang, Huanzhong; Wei, Mao

2015-09-01

Approximately 400000t of DDTs/HCHs-contaminated soil (CS) needed to be co-processed in a cement kiln with a time limitation of 2y. A new pre-processing facility with a "drying, grinding and DDTs/HCHs vaporizing" ability was equipped to meet the technical requirements for processing cement raw meal and the environmental standards for stack emissions. And the bottom of the precalciner with high temperatures >1000°C was chosen as the CS feeding point for co-processing, which has rarely been reported. To assess the environmental performance of CS pre- and co-processing technologies, according to the local regulation, a test burn was performed by independent and accredited institutes systematically for determination of the clinker quality, kiln stack gas emissions and destruction efficiency of the pollutant. The results demonstrated that the clinker was of high quality and not adversely affected by CS co-processing. Stack emissions were all below the limits set by Chinese standards. Particularly, PCDD/PCDF emissions ranged from 0.0023 to 0.0085ngI-TEQNm(-3). The less toxic OCDD was the peak congener for CS co-processing procedure, while the most toxic congeners (i.e. 2,3,7,8-TeCDD, 1,2,3,7,8-PeCDD and 2,3,4,7,8-PeCDD) remained in a minor proportion. Destruction and removal efficiency (DRE) and destruction efficiency (DE) of the kiln system were better than 99.9999% and 99.99%, respectively, at the highest CS feeding rate during normal production. To guarantee the environmental performance of the system the quarterly stack gas emission was also monitored during the whole period. And all of the results can meet the national standards requirements. Copyright © 2015 Elsevier Ltd. All rights reserved.

Distributions and concentrations of thallium in Korean soils determined by single and sequential extraction procedures.

Science.gov (United States)

Lee, Jin-Ho; Kim, Dong-Jin; Ahn, Byung-Koo

2015-06-01

The objectives of this study were to investigate the distribution of thallium in soils collected near suspected areas such as cement plants, active and closed mines, and smelters and to examine the extraction of thallium in the soils using 19 single chemical and sequential chemical extraction procedures. Thallium concentrations in soils near cement plants were distributed between 1.20 and 12.91 mg kg(-1). However, soils near mines and smelters contained relatively low thallium concentrations ranging from 0.18 to 1.09 mg kg(-1). Thallium extractability with 19 single chemical extractants from selected soils near cement plants ranged from 0.10% to 8.20% of the total thallium concentration. In particular, 1.0 M NH4Cl, 1.0 M (NH4)2SO4, and 1.0 M CH3COONH4 extracted more thallium than other extractants. Sequential fractionation results of thallium from different soils such as industrially and artificially contaminated soils varied with the soil properties, especially soil pH and the duration of thallium contamination.

Influence of farmyard manure on some morphological and biochemical parameters of cowpea (Vigna unguiculata) seedling grown in cadmium-treated soil.

Science.gov (United States)

Asagba, Samuel Ogheneovo; Ezedom, Theresa; Kadiri, Helen

2017-10-01

The present study aims to assess the effects of the two kinds of farmyard manure (poultry and pig manures) as amendments for soil on cadmium (Cd) toxicity in plants using cowpea seedlings as plant model. Cd toxicity was evaluated by assessing the effect of the metal on the growth rate and antioxidant status as well as the ability of the plant to metabolise xenobiotic. There was a significantly (p cowpea seedlings grown in all the treated soils relative to control. Addition of poultry manure to the soil significantly (p cowpea seedlings grown in Cd-treated soil augmented with poultry manure but not in cowpea seedlings in cadmium-treated soil with pig manure amendments. Similarly, augmentation of Cd-treated soil with pig manure did not alter the Cd-induced effect on the levels of superoxide dismutase (SOD) and lipid peroxidation (LPO) in leaf, stem and roots, as SOD remained significantly (p cowpea seedlings grown in Cd-treated soils amended with poultry manure were restored to a level not significantly (p > 0.05) different from control. Like in the case of SOD, the Cd-induced inhibition of the activity of xenobiotic metabolising enzymes, aldehyde oxidase and sulphite oxidase remained significantly (p  0.05) different from control. In conclusion, the findings of the study revealed that supplementation of Cd-treated soils with pig and poultry manures reversed effects of Cd on cowpea seedlings. However, poultry manure was more effective than pig manure in ameliorating the effects of Cd.

ALTERNATIVE FIELD METHODS TO TREAT MERCURY IN SOIL

International Nuclear Information System (INIS)

Stine, Ernie F.

2002-01-01

The Department of Energy (DOE) currently has mercury (Hg) contaminated materials and soils at the various sites. Figure 1-1 (from http://www.ct.ornl.gov/stcg.hg/) shows the estimated distribution of mercury contaminated waste at the various DOE sites. Oak Ridge and Idaho sites have the largest deposits of contaminated materials. The majorities of these contaminated materials are soils, sludges, debris, and waste waters. This project concerns treatment of mercury contaminated soils. The technology is applicable to many DOE sites, in-particular, the Y-12 National Security Complex in Oak Ridge Tennessee and Idaho National Engineering and Environmental Laboratory (INEEL). These sites have the majority of the soils and sediments contaminated with mercury. The soils may also be contaminated with other hazardous metals and radionuclides. At the Y12 plant, the baseline treatment method for mercury contaminated soil is low temperature thermal desorption (LTTD), followed by on-site landfill disposal. LTTD is relatively expensive (estimated cost of treatment which exclude disposal cost for the collect mercury is greater than $740/per cubic yard [cy] at Y-12), does not treat any of the metal or radionuclides. DOE is seeking a less costly alternative to the baseline technology. As described in the solicitation (DE-RA-01NT41030), this project initially focused on evaluating cost-effective in-situ alternatives to stabilize or remove the mercury (Hg) contamination from high-clay content soil. It was believed that ex-situ treatment of soil contaminated with significant quantities of free-liquid mercury might pose challenges during excavation and handling. Such challenges may include controlling potential mercury vapors and containing liquid mercury beads. As described below, the focus of this project was expanded to include consideration of ex-situ treatment after award of the contract to International Technology Corporation (IT). After award of the contract, IT became part of Shaw

ALTERNATIVE FIELD METHODS TO TREAT MERCURY IN SOIL

Energy Technology Data Exchange (ETDEWEB)

Ernie F. Stine

2002-08-14

The Department of Energy (DOE) currently has mercury (Hg) contaminated materials and soils at the various sites. Figure 1-1 (from http://www.ct.ornl.gov/stcg.hg/) shows the estimated distribution of mercury contaminated waste at the various DOE sites. Oak Ridge and Idaho sites have the largest deposits of contaminated materials. The majorities of these contaminated materials are soils, sludges, debris, and waste waters. This project concerns treatment of mercury contaminated soils. The technology is applicable to many DOE sites, in-particular, the Y-12 National Security Complex in Oak Ridge Tennessee and Idaho National Engineering and Environmental Laboratory (INEEL). These sites have the majority of the soils and sediments contaminated with mercury. The soils may also be contaminated with other hazardous metals and radionuclides. At the Y12 plant, the baseline treatment method for mercury contaminated soil is low temperature thermal desorption (LTTD), followed by on-site landfill disposal. LTTD is relatively expensive (estimated cost of treatment which exclude disposal cost for the collect mercury is greater than $740/per cubic yard [cy] at Y-12), does not treat any of the metal or radionuclides. DOE is seeking a less costly alternative to the baseline technology. As described in the solicitation (DE-RA-01NT41030), this project initially focused on evaluating cost-effective in-situ alternatives to stabilize or remove the mercury (Hg) contamination from high-clay content soil. It was believed that ex-situ treatment of soil contaminated with significant quantities of free-liquid mercury might pose challenges during excavation and handling. Such challenges may include controlling potential mercury vapors and containing liquid mercury beads. As described below, the focus of this project was expanded to include consideration of ex-situ treatment after award of the contract to International Technology Corporation (IT). After award of the contract, IT became part of Shaw

The Effect of Abutment Surface Roughness on the Retention of Implant-Supported Crowns Cemented with Provisional Luting Cement

Directory of Open Access Journals (Sweden)

Jalil Ganbarzadeh

2013-01-01

Full Text Available Introduction: Surface roughness can increase the retention of castings by ridges and grooves that are microretentive. This study compared the retention of implant-supported crowns when used with 3 different surface roughness abutments and one temporary cement. Methods: Thirty solid abutments (ITI, 4 mm high, were divided into three groups randomly. In the first group, 10 abutments were roughened with sandblast (50-µm aluminum oxide and in the second group, 10 abutments were roughened with diamond bur. The third group had no surface treatment. Then, thirty implant fixture analogs (ITI were placed in the center of acrylic cylinders. After that a solid abutment was tightened on the each fixture analog with 35 N/cm force. Thirty base metal crowns were made on the 4 mm ITI abutment analogs using plastic coping. The prepared copings were cemented on the abutments by TempBond temporary cement and finally, crowns were pulled from the abutment in a universal test machine at a cross speed of 0.5cm/min. Results: The mean tensile strength in sandblasted, bur treated, and control group were 64.38±8, 91.37±7.19, and 58.61±1.93, respectively. Bur treated group showed higher tensile strength in comparison with two other groups. Conclusion: Surface modification of implant abutment by diamond bur may be an effective method to increase retention of crown when TempBond is used.

Evaluation of the amount of excess cement around the margins of cement-retained dental implant restorations: the effect of the cement application method.

Science.gov (United States)

Chee, Winston W L; Duncan, Jesse; Afshar, Manijeh; Moshaverinia, Alireza

2013-04-01

Complete removal of excess cement from subgingival margins after cementation of implant-supported restorations has been shown to be unpredictable. Remaining cement has been shown to be associated with periimplant inflammation and bleeding. The purpose of this study was to investigate and compare the amount of excess cement after cementation with 4 different methods of cement application for cement-retained implant-supported restorations. Ten implant replicas/abutments (3i) were embedded in acrylic resin blocks. Forty complete veneer crowns (CVCs) were fabricated by waxing onto the corresponding plastic waxing sleeves. The wax patterns were cast and the crowns were cemented to the implant replicas with either an interim (Temp Bond) or a definitive luting agent (FujiCEM). Four methods of cement application were used for cementation: Group IM-Cement applied on the internal marginal area of the crown only; Group AH-Cement applied on the apical half of the axial walls of the crown; Group AA-Cement applied to all axial walls of the interior surface of the crown, excluding the occlusal surface; and Group PI-Crown filled with cement then seated on a putty index formed to the internal configuration of the restoration (cementation device) (n=10). Cement on the external surfaces was removed before seating the restoration. Cement layers were applied on each crown, after which the crown was seated under constant load (80 N) for 10 minutes. The excess cement from each specimen was collected and measured. One operator performed all the procedures. Results for the groups were compared, with 1 and 2-way ANOVA and the Tukey multiple range test (α=.05). No significant difference in the amount of excess/used cement was observed between the 2 different types of cements (P=.1). Group PI showed the least amount of excess cement in comparison to other test groups (P=.031). No significant difference was found in the amount of excess cement among groups MI, AH, and AA. Group AA showed the

76 FR 76760 - Gray Portland Cement and Cement Clinker From Japan

Science.gov (United States)

2011-12-08

... and Cement Clinker From Japan Determination On the basis of the record \\1\\ developed in the subject... duty order on gray Portland cement and cement clinker from Japan would be likely to lead to... and Cement Clinker from Japan: Investigation No. 731- TA-461 (Third Review). By order of the...

Treatment of root fracture with accompanying resorption using cermet cement.

Science.gov (United States)

Lui, J L

1992-02-01

A method of treating an apical root fracture with accompanying resorption at the junction of the fracture fragments using glass-cermet cement is described. Endodontically, the material had previously been used for repair of lateral resorptive root defects and retrograde root fillings. Complete bone regeneration was observed three years post-operatively following treatment of the root fracture in the conventional manner. The various advantages of glass-cermet cement as a root filling material used in the technique described are discussed.

Assessment of genotoxic effects of pesticide and vermicompost treated soil with Allium cepa test

Directory of Open Access Journals (Sweden)

Shivika Datta

2018-07-01

Full Text Available Soil forms a huge reservoir of nutrients that sustains life on earth. Anthropogenic and natural impacts have led to degradation of land which declines the overall quality of soil, water or vegetation. The present study involves comparison of genotoxicity of soil procured from two different agricultural sites, pesticide treated soil (PTS and vermicompost treated soil (VTS. The soil was physico-chemically characterized and showed significant differences in terms of cytotoxicity (root length; mitotic index and genotoxicity (chromosomal aberrations in Allium cepa test. The mitotic index of the control after 24 and 48 h was found to be 26.1 ± 1.6 and 26.1 ± 1.3 respectively. Mitotic index was reduced to 10.3 ± 0.9 and 9.7 ± 0.6 in 100% PTS and 24.4 ± 1.7 and 25.4 ± 0.8 in 100% VTS after 24 and 48 h of exposure, respectively. Clastogenic aberrations were found to be highest (54.5% in 100% PTS which was significantly different from VTS extract. The PTS extracts incurred significantly more cytotoxic and genotoxic effects on A. cepa in comparison to VTS. The result indicates that addition of vermicompost in agriculture field acts as soil ameliorator and plays an important role in promotion of cell division and proliferation, hence good for the plant health and crop productivity.

Phytoremediation of Cadmium and Chromium by Plants around Ardabil Cement Factory

OpenAIRE

Samira Hosseini; Marziyeh Mosayebi

2016-01-01

Heavy metals are the most important sources of non-point pollution of natural resources. Every year, thousands of these elements on a global scale enter to the soil system. The aim of this study was to investigate the phytoremediation of cadmium and chromium by plants around Ardabil Cement Factory. With field work and presence in the field of soil and plant samples need to be prepared. Statistical analysis is performed using the SPSS software. For this purpose, analysis of variance was used t...

Physical, chemical and mineralogical characterization of water treatment plant waste for use in soil-cement brick; Caracterizacao fisica, quimica e mineralogica de residuo de estacao de tratamento de aguas para aproveitamento em tijolo solo-cimento

Energy Technology Data Exchange (ETDEWEB)

Pessin, L.R.; Destefani, A.Z.; Holanda, J.N.F., E-mail: larapessin@hotmail.com [Universidade Estadual do Norte Fluminense Darcy Ribeiro (CCT/PPGECM/UENF), Campos dos Goytacazes, RJ (Brazil)

2011-07-01

The water treatment plants (WTP) for human consumption generate huge amounts of waste in the form of sludge (sludge) that have been over the years mostly inadequately prepared in water resources and the environment. Moreover, traditional methods of disposal of waste water treatment plants commonly used are generally costly activities. An alternative method for disposal of this waste abundant is its incorporation in ceramic products. This work is focused on the physical-chemical and mineralogical composition of a sample of waste water treatment plants from the region of Campos dos Goytacazes-RJ to their use in the manufacture of soil-cement brick. Several characterization techniques were used including X-ray diffraction, X-ray fluorescence, scanning electron microscopy, picnometry, particle size analysis and plasticity. The experimental results indicate that the waste water treatment plants have the potential to be used in the manufacture of ecologic soil-cement bricks. (author)

Cementing a wellbore using cementing material encapsulated in a shell

Energy Technology Data Exchange (ETDEWEB)

Aines, Roger D.; Bourcier, William L.; Duoss, Eric B.; Spadaccini, Christopher M.; Cowan, Kenneth Michael

2016-08-16

A system for cementing a wellbore penetrating an earth formation into which a pipe extends. A cement material is positioned in the space between the wellbore and the pipe by circulated capsules containing the cement material through the pipe into the space between the wellbore and the pipe. The capsules contain the cementing material encapsulated in a shell. The capsules are added to a fluid and the fluid with capsules is circulated through the pipe into the space between the wellbore and the pipe. The shell is breached once the capsules contain the cementing material are in position in the space between the wellbore and the pipe.

Cementing a wellbore using cementing material encapsulated in a shell

Energy Technology Data Exchange (ETDEWEB)

Aines, Roger D.; Bourcier, William L.; Duoss, Eric B.; Floyd, III, William C.; Spadaccini, Christopher M.; Vericella, John J.; Cowan, Kenneth Michael

2017-03-14

A system for cementing a wellbore penetrating an earth formation into which a pipe extends. A cement material is positioned in the space between the wellbore and the pipe by circulated capsules containing the cement material through the pipe into the space between the wellbore and the pipe. The capsules contain the cementing material encapsulated in a shell. The capsules are added to a fluid and the fluid with capsules is circulated through the pipe into the space between the wellbore and the pipe. The shell is breached once the capsules contain the cementing material are in position in the space between the wellbore and the pipe.

Heavy metals speciation in soils treated with sewage sludges

International Nuclear Information System (INIS)

Forero Hernandez, Adriana; Ballesteros Gonzalez, Maria Ines

2004-01-01

The chemical speciation in soils that had been treated with sewage sludge was determined to find out what had occurred to the heavy metals present. This was done nine weeks after sludge application. An incubation assay was realized using 2.5 % w/w sludge level; this is equivalent to 81.5 ton of sludge per hectare. Pots filled with sludge-soil mixture were placed in a greenhouse at temperature between 17 and 25 Celsius degrade, humidity at field capacity distributed in accordance with a random experimental design with four replicates and seven treatments. It was found that the concentration of Cd, Cu, Mn, Pb, and Zn was lower than the limits established by the environmental protection agency (EPA) for soil usage. Also, the organic carbon content, the available nitrogen and phosphorus were in the normal concentration range reported for organic fertilizers. The sludge addition to the soil gave significant increase of the fraction of Cd bounded to organic material as compared with the exchangeable fraction and the fraction bounded to iron-manganese oxides. Cooper showed more affinity for the fraction of iron-manganese oxides. Lead gave a fraction bounded to organic material that was absent in the witness samples. Zinc had a bigger proportion in the fraction associated with iron manganese oxides. Manganese as compared with the other metals showed the biggest unchangeable fraction

Biological functioning of PAH-polluted and thermal desorption-treated soils assessed by fauna and microbial bioindicators.

Science.gov (United States)

Cébron, Aurélie; Cortet, Jérôme; Criquet, Stéven; Biaz, Asmaa; Calvert, Virgile; Caupert, Cécile; Pernin, Céline; Leyval, Corinne

2011-11-01

A large number of soil bioindicators were used to assess biological diversity and activity in soil polluted with polycyclic aromatic hydrocarbons (PAHs) and the same soil after thermal desorption (TD) treatment. Abundance and biodiversity of bacteria, fungi, protozoa, nematodes and microarthropods, as well as functional parameters such as enzymatic activities and soil respiration, were assessed during a two year period of in situ monitoring. We investigated the influence of vegetation (spontaneous vegetation and Medicago sativa) and TD treatment on biological functioning. Multivariate analysis was performed to analyze the whole data set. A principal response curve (PRC) technique was used to evaluate the different treatments (various vegetation and contaminated vs. TD soil) contrasted with control (bare) soil over time. Our results indicated the value of using a number of complementary bioindicators, describing both diversity and functions, to assess the influence of vegetation on soil and discriminate polluted from thermal desorption (TD)-treated soil. Plants had an influence on the abundance and activity of all organisms examined in our study, favoring the whole trophic chain development. However, although TD-treated soil had a high abundance and diversity of microorganisms and fauna, enzymatic activities were weak because of the strong physical and chemical modifications of this soil. Copyright © 2011 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Natural cement as the precursor of Portland cement: Methodology for its identification

International Nuclear Information System (INIS)

Varas, M.J.; Alvarez de Buergo, M.; Fort, R.

2005-01-01

When cements appeared in the 19th century, they took the place of traditional binding materials (lime, gypsum, and hydraulic lime) which had been used until that time. Early cements can be divided into two groups, natural and artificial (Portland) cements. Natural cements were introduced first, but their widespread usage was short-lived as they were quickly replaced by artificial cements (Portland), still the most important and predominant today. The main differences between natural and artificial cements arise during the manufacturing process. The final properties of the cements are greatly influenced by differences in the raw materials and burning temperatures employed. The aim of this paper is to assess the efficiency of traditional analytical techniques (petrographic microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR)) used to differentiate natural and artificial cements

The assessment of treated wastewater quality and the effects of mid-term irrigation on soil physical and chemical properties (case study: Bandargaz-treated wastewater)

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Kaboosi, Kami

2017-09-01

This study was conducted to investigate the characteristics of inflow and outflow wastewater of the Bandargaz wastewater treatment plant on the basis of the data collection of operation period and the samples taken during the study. Also the effects of mid-term use of the wastewater for irrigation (from 2005 to 2013) on soil physical and chemical characteristics were studied. For this purpose, 4 samples were taken from the inflow and outflow wastewater and 25 quality parameters were measured. Also, the four soil samples from a depth of 0-30 cm of two rice field irrigated with wastewater in the beginning and middle of the planting season and two samples from one adjacent rice field irrigated with fresh water were collected and their chemical and physical characteristics were determined. Average of electrical conductivity, total dissolved solids, sodium adsorption ratio, chemical oxygen demand and 5 days biochemical oxygen demand in treated wastewater were 1.35 dS/m, 707 ppm, 0.93, 80 ppm and 40 ppm, respectively. Results showed that although some restrictions exist about chlorine and bicarbonate, the treated wastewater is suitable for irrigation based on national and international standards and criteria. In comparison with fresh water, the mid-term use of wastewater caused a little increase of soil salinity. However, it did not lead to increase of soil salinity beyond rice salinity threshold. Also, there were no restrictions on soil in the aspect of salinity and sodium hazard on the basis of many irrigated soil classifications. In comparison with fresh water, the mid-term use of wastewater caused the increase of total N, absorbable P and absorbable K in soil due to high concentration of those elements in treated wastewater.

Accelerated test for measuring sulfate resistance of hydraulic cements for Caltrans LLPRS program

Science.gov (United States)

2000-04-01

Many California soils are rich in sulfates, which can have deleterious effects on the cements used in rigid pavements. Field experience has demonstrated that sulfate attack usually manifests itself in the form of loss of adhesion and strength. In ord...

stabilized lateritic soil

African Journals Online (AJOL)

user

this work to optimize the amount of bagasse ash content in cement-stabilized lateritic soil. Geometric .... can handle or consider all the properties involved at the same time to ...... Bearig Ratio of Used oil contaminated Lateritic soils” Nigerian ...

An Investigation Into The Effect Of Mixtures Of Lateritic-Cement And ...

African Journals Online (AJOL)

The behaviour of the laterite-cement, shale, and limedust when mixed in proportions to mould bricks under natural conditions and the improvement of structural properties of laterite for wider and more economical usage as construction material were investigated. Shale was found to be a very poor soil stabilizer because it ...

Soil-food chain-pesticide wildlife relationships in aldrin-treated fields

Science.gov (United States)

Korschgen, L.J.

1970-01-01

Soil-food-chain-pesticide wildlife relationships were investigated to learn the concentration of pesticide residues present in soils, macro-invertebrates, vertebrates, and seeds as a result of annual applications of aldrin at recommended rates for pest control. Two central Missouri cornfields treated witb aldrin at 1 lb/acre, for 16 and 15 of the past 17 years, were selected for study during 1965-67. Primary samples collected for residue analyses included soils, earthworms (Lumbricidae), crickets (GryIlidae), and two kinds of ground beetles (Carabidae) obtained during early April, June, August, and October. Vertebrates and plant seeds collected during 1967 included white-footed mice (Peromyscus maniculatus), toads (Bufo americanus), snakes (Thamnophis sirtalis and Pituophis sayi), corn (Zea Mays), foxtail (Setaria Faberii), and annual sunflower (Helianthus annuus). Pesticide residues consisted primarily of dieldrin, the degradation product of aldrin. Combined aldrin and dieldrin residues, as two field all-season averages, wet weight basis, were: soils, 0.31 ppm; earthworms, 1.49 ppm; crickets, 0.23 ppm; Harpalus ground beetles, 1.10 ppm; Poecilus ground beetles, 9.67 ppm; white-footed mice, 0.98 ppm; toads, 3.53 ppm; garter snakes, 12.35 ppm; and corn, foxtail, and sunflower seeds less than 0.02 ppm each. Unusually high average residues (37.48 ppm) in Poecilus beetles during June, 1967, were attributed to abnormally high soil moisture and predacious feeding habits of these insects.

Estimation of Corn Yield and Soil Nitrogen via Soil Electrical Conductivity Measurement Treated with Organic, Chemical and Biological Fertilizers

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H. Khalilzade

2016-02-01

titration, N is acid normality. The microbial respiration (mgCO2/g(dry soil.day1 calculated by dividing the record CO2 volume to number of days that sample have been placed on container plus dry weight of soil sample. Results and Discussion Results showed that soils treated with vermicompost and manure had the highest level of nitrogen during the growing season. Higher microbial respiration was recorded in soils treated with biological fertilizer. Changes in soil nitrogen and electrical conductivity was against each other and correlation results showed that soil nitrogen could be estimated via measurement of soil electrical conductivity. Changes of pH and soil nitrogen were similar and there was a significant correlation between them. Eigenberg et al. (8 suggested that the pattern of changes of soil electrical conductivity is highly dependent on soil conditions; also soil water and nutrient content are of the most important factors in determining soil EC. There is a significant and negative correlation between soil electrical conductivity and grain yield and it seems that in this region grain yield of maize can be estimated via measurement of soil electrical conductivity. Conclusions In general, the results indicated that there was a strong and negative relation between EC and soil N content. Also, soil EC showed a negative correlation with maize yield which suggested that it is possible to estimate soil N and maize yield through soil EC measurement during of the growing season in the study area.

Feasibility of producing nano cement in a traditional cement factory in Iraq

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Sada Abdalkhaliq Hasan Alyasri

2017-12-01

Full Text Available This study investigates the economic feasibility of producing nano cement through the establishment of a production line within an existing cement factory. Creating a nano cement production line within the Alkufa Cement factory in Iraq is selected as a case study. Evaluation measures including internal rate of return (IRR, net present value (NPV and breakeven point (BEP are used to evaluate the possible gain that can be achieved from this option. The results demonstrated a positive NPV. The IRR is found to be 26.8% and BEP is reached within 3 years after the establishment of the line. This indicates that producing nano cement in the existing cement factory is economically feasible and can be more advantageous than the ordinary cement.

The mechanical effect of the existing cement mantle on the in-cement femoral revision.

Science.gov (United States)

Keeling, Parnell; Lennon, Alexander B; Kenny, Patrick J; O'Reilly, Peter; Prendergast, Patrick J

2012-08-01

Cement-in-cement revision hip arthroplasty is an increasingly popular technique to replace a loose femoral stem which retains much of the original cement mantle. However, some concern exists regarding the retention of the existing fatigued and aged cement in such cement-in-cement revisions. This study investigates whether leaving an existing fatigued and aged cement mantle degrades the mechanical performance of a cement-in-cement revision construct. Primary cement mantles were formed by cementing a polished stem into sections of tubular steel. If in the test group, the mantle underwent conditioning in saline to simulate ageing and was subject to a fatigue of 1 million cycles. If in the control group no such conditioning or fatigue was carried out. The cement-in-cement procedure was then undertaken. Both groups underwent a fatigue of 1 million cycles subsequent to the revision procedure. Application of a Mann-Whitney test on the recorded subsidence (means: 0.51, 0.46, n=10+10, P=0.496) and inducible displacement (means: 0.38, 0.36, P=0.96) revealed that there was no statistical difference between the groups. This study represents further biomechanical investigation of the mechanical behaviour of cement-in-cement revision constructs. Results suggest that pre-revision fatigue and ageing of the cement may not be deleterious to the mechanical performance of the revision construct. Thus, this study provides biomechanical evidence to back-up recent successes with this useful revision technique. Copyright © 2012 Elsevier Ltd. All rights reserved.

effect of compactive effort on strength indices of laterite treated

African Journals Online (AJOL)

PROF. BARTH EKWEME

Atterberg's limits test, compaction test, California bearing ratio (CBR) and unconfined ... size, highclay content, and the degree to which the soils have been ... in the stabilization of Ikpayongo laterite with cement. However lime which seems to be the conventional ... as soil modification or stabilization, depending on treatment ...

Sustainable Development of the Cement Industry and Blended Cements to Meet Ecological Challenges

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Konstantin Sobolev

2003-01-01

Full Text Available The world production of cement has greatly increased in the past 10 years. This trend is the most significant factor affecting technological development and the updating of manufacturing facilities in the cement industry. Existing technology for the production of cement clinker is ecologically damaging; it consumes much energy and natural resources and also emits pollutants. A new approach to the production of blended or high-volume mineral additive (HVMA cement helps to improve its ecological compatibility. HVMA cement technology is based on the intergrinding of portland cement clinker, gypsum, mineral additives, and a special complex admixture. This new method increases the compressive strength of ordinary cement, improves durability of the cement-based materials, and - at the same time - uses inexpensive natural mineral additives or industrial by-products. This improvement leads to a reduction of energy consumption per unit of the cement produced. Higher strength, better durability, reduction of pollution at the clinker production stage, and decrease of landfill area occupied by industrial by-products, all provide ecological advantages for HVMA cement.

Cement for Oil Well Cementing Operations in Ghana

African Journals Online (AJOL)

Michael

For Portland cement to qualify as oil well cement, the chemical and physical properties must meet ..... Reservoir Engineering, Stanford University,. Stanford, California, pp. ... Construction”, PhD Thesis, Kwame Nkrumah. University of Science ...

Low force cementation.

Science.gov (United States)

Wilson, P R

1996-07-01

The marginal adaptation of full coverage restorations is adversely affected by the introduction of luting agents of various minimum film thicknesses during the cementation process. The increase in the marginal opening may have long-term detrimental effects on the health of both pulpal and periodontal tissues. The purpose of this study was to determine the effects of varying seating forces (2.5, 12.5, 25 N), venting, and cement types on post-cementation marginal elevation in cast crowns. A standardized cement space of 40 microns was provided between a machined gold crown and a stainless steel die. An occlusal vent was placed that could be opened or closed. The post-cementation crown elevation was measured, following the use of two commercially available capsulated dental cements (Phosphacap, and Ketac-cem Applicap). The results indicate that only the combination of Ketac-Cem Applicap and crown venting produced post-cementation crown elevation of less than 20 microns when 12.5 N seating force was used. Higher forces (25 N) and venting were required for comparable seating when using Phosphacap (19 microns). The amount of force required to allow maximum seating of cast crowns appears to be cement specific, and is reduced by effective venting procedures.

Synthesis of Portland cement and calcium sulfoaluminate-belite cement for sustainable development and performance

Science.gov (United States)

Chen, Irvin Allen

Portland cement concrete, the most widely used manufactured material in the world, is made primarily from water, mineral aggregates, and portland cement. The production of portland cement is energy intensive, accounting for 2% of primary energy consumption and 5% of industrial energy consumption globally. Moreover, portland cement manufacturing contributes significantly to greenhouse gases and accounts for 5% of the global CO2 emissions resulting from human activity. The primary objective of this research was to explore methods of reducing the environmental impact of cement production while maintaining or improving current performance standards. Two approaches were taken, (1) incorporation of waste materials in portland cement synthesis, and (2) optimization of an alternative environmental friendly binder, calcium sulfoaluminate-belite cement. These approaches can lead to less energy consumption, less emission of CO2, and more reuse of industrial waste materials for cement manufacturing. In the portland cement part of the research, portland cement clinkers conforming to the compositional specifications in ASTM C 150 for Type I cement were successfully synthesized from reagent-grade chemicals with 0% to 40% fly ash and 0% to 60% slag incorporation (with 10% intervals), 72.5% limestone with 27.5% fly ash, and 65% limestone with 35% slag. The synthesized portland cements had similar early-age hydration behavior to commercial portland cement. However, waste materials significantly affected cement phase formation. The C3S--C2S ratio decreased with increasing amounts of waste materials incorporated. These differences could have implications on proportioning of raw materials for cement production when using waste materials. In the calcium sulfoaluminate-belite cement part of the research, three calcium sulfoaluminate-belite cement clinkers with a range of phase compositions were successfully synthesized from reagent-grade chemicals. The synthesized calcium sulfoaluminate

Ultrafine portland cement performance

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C. Argiz

2018-04-01

Full Text Available By mixing several binder materials and additions with different degrees of fineness, the packing density of the final product may be improved. In this work, ultrafine cement and silica fume mixes were studied to optimize the properties of cement-based materials. This research was performed in mortars made of two types of cement (ultrafine Portland cement and common Portland cement and two types of silica fume with different particle-size distributions. Two Portland cement replacement ratios of 4% and 10% of silica fume were selected and added by means of a mechanical blending method. The results revealed that the effect of the finer silica fume mixed with the coarse cement enhances the mechanical properties and pore structure refinement at a later age. This improvement is somewhat lower in the case of ultrafine cement with silica fume.

Effects of chromium exposure from a cement factory

International Nuclear Information System (INIS)

Isikli, B.; Demir, T.A.; Uerer, S.M.; Berber A.; Akar, T.; Kalyoncu, C.

2003-01-01

The aim of the study was to determine the chromium concentrations of soil and plant specimens taken from a rural area exposed to cement factory emissions and also to determine the blood concentrations and sensitivity conditions observed in humans residing in this rural area. The study was carried out in Cukurhisar, a town in Eskisehir-Turkey, between May 2000 an March 2001. Besides the 108 soil (36 for control) and plant specimens, which were taken from eight different directions from the cement factory, blood samples of the individuals residing in this area were taken from 258 subject (258 for control) following a physical examination, and patch tests were als applied. The chromium concentrations of the soil and plant specimens take from different places in different directions of the factory were higher than in the control areas. The physical examination of subjects did not reveal results different from those of the control group except for the diagnosis of contact dermatitis. The analyses of venous blood samples showed that chromium concentrations were found to be within the reference values given for bot groups, but higher in the subjects (P<0.001). According to the results o patch tests, sensitivity to chromium was found to be more frequent for the subject group than the control group (P<0.05). According to these results clinical tools revealed no toxic effects for the subjects, except contact dermatitis. However, sensitivity to patch tests showed that this subject group has been affected compared to the control group and that this effect increased with age

Effect of oil pollution on function of sandy soils in protected deserts and investigation of their improvement guidelines (case study: Kalmand area, Iran).

Science.gov (United States)

Saberian, Mohammad; Khabiri, Mohammad Mehdi

2018-02-01

Soil pollution is one of the most dangerous sorts of environmental pollutions because of waste materials, fossil fuels, etc. Unfortunately in developing countries, there are very few arrangements to prevent soil pollution due to the fossil fuels and to improve polluted soil. In this research, influences of gas oil on properties of Kalmand protected area's sandy soil near Yazd, Iran, were studied. It was found that gas oil constituted 5.25% of soil weight in the refueling station in the region. Therefore, cleaning and strengthening of the soil by adding cement rather than expensive and complicated methods were the most important goals of this research. First, the influence of gas oil on soil properties was studied, and to improve the soil, different percentages of ordinary portland cement were added to the polluted sand to study the improved soil properties using laboratory tests. It was found that unconfined compressive strength, cohesion, and angle of internal friction of sample with 16% cement and 8% gas oil after 28 days of curing were higher than those of the specimen of 6% cement and 14% gas oil, at 4.6, 5.4, and 1.3 times, respectively. Moreover, based on falling head tests it was observed that permeability of the stabilized specimens decreased substantially. From SEM tests, fewer voids were observed in the stabilized samples, which led to less pollutant penetration into the soil. According to EDX, although dangerous elements in the contaminated specimen made up 3.99% of the specimen total weight, addition of cement introduced considerable amounts of elements that are vital for pozzolanic reactions. Therefore, it can be concluded that addition of cement to the gas oil-polluted soil not only can improve geotechnical properties of the soil and reduce its permeability, but also is very efficient for environmental issues.

Crumb waste tire rubber surface modification by plasma polymerization of ethanol and its application on oil-well cement

Science.gov (United States)

Xiaowei, Cheng; Sheng, Huang; Xiaoyang, Guo; Wenhui, Duan

2017-07-01

Crumb waste tire rubber (WTR) was pretreated by oxygen low temperature plasma (LTP) and modified by LTP polymerization process of ethanol monomer to improve the adhesion property with oil-well cement matrix and the mechanical properties of cement. The surface properties of modified crumb WTR and the mechanical properties and structures of modified oil-well cement were investigated by means of contact angle measurement, dispersion test, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), mechanics performance tests, permeability test and scanning electron microscopy (SEM). It was demonstrated that LTP treatment changed both the surface composition and roughness. The contact angle of pretreated crumb WTR dramatically fell from 122° to 34°, and sample with ethanol LPT polymer film decreased even further to 11°. The ATR-FTIR and XPS analysis results demonstrated that hydrophilic groups, such as -COOH, C-OH, and -CHO, were introduced on the WTR surface. The oxygen atomic percent increased from 8.11% to 14.50% and 24.83%. The mechanical properties, porosity and permeability of raw cement were compared to samples modified by untreated crumb WTR, pretreated crumb WTR and ethanol LTP polymerization treated crumb WTR. It was found that after 28 days, the compressive strength of the samples with the untreated crumb WTR decreased to 80% with respect to raw cement. The tensile strength and flexural strength also had a slight reduction compared with the raw cement. On the contrary, after 28 days, the tensile strength of cement modified by LTP polymerization treated WTR increased 11.03% and 13.36%, and the flexural strength increased 9.65% and 7.31%, respectively. A decrease in the compressive strength also occurred but was inconspicuous. A tight interface bonding for ethanol LTP polymerization treated WTR with cement matrix was observed via an SEM image.

Cytotoxicity and biocompatibility of Zirconia (Y-TZP posts with various dental cements

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Hyeongsoon Shin

2016-08-01

Full Text Available Objectives Endodontically treated teeth with insufficient tooth structure are often restored with esthetic restorations. This study evaluated the cytotoxicity and biological effects of yttria partially stabilized zirconia (Y-TZP blocks in combination with several dental cements. Materials and Methods Pairs of zirconia cylinders with medium alone or cemented with three types of dental cement including RelyX U200 (3M ESPE, FujiCEM 2 (GC, and Panavia F 2.0 (Kuraray were incubated in medium for 14 days. The cytotoxicity of each supernatant was determined using 3-(4,5-dimethylthiazole-2-yl-2,5-diphenyltetrazolium bromide (MTT assays on L929 fibroblasts and MC3T3-E1 osteoblasts. The levels of interleukin-6 (IL-6 mRNA were evaluated by reverse transcription polymerase chain reaction (RT-PCR, and IL-6 protein was evaluated by enzyme-linked immunosorbent assays (ELISA. The data were analyzed using one-way ANOVA and Tukey post-hoc tests. A p < 0.05 was considered statistically significant. Results The MTT assays showed that MC3T3-E1 osteoblasts were more susceptible to dental cements than L929 fibroblasts. The resin based dental cements increased IL-6 expression in L929 cells, but reduced IL-6 expression in MC3T3-E1 cells. Conclusions Zirconia alone or blocks cemented with dental cement showed acceptable biocompatibilities. The results showed resin-modified glass-ionomer based cement less produced inflammatory cytokines than other self-adhesive resin-based cements. Furthermore, osteoblasts were more susceptible than fibroblasts to the biological effects of dental cement.

Radon induced radiological impact of coal, fly ash and cement samples

International Nuclear Information System (INIS)

Kant, K.; Chauhan, R.P.; Sharma, G.S.; Chakravarti, S.K.

2001-01-01

Coal and its by-product fly ash are technologically important materials being used for power generation and in the manufacture of bricks, sheets, cement, land-filling, etc., respectively. Increased interest in measuring radon concentration in coal, fly ash and cement is due to its health hazards and environmental pollution. As the presence of radon in the environment (indoor and outdoor), soil, ground water, oil and gas deposits contributes the largest fraction of the natural radiation dose to populations, tracking its concentration is thus of paramount importance for radiological protection. Samples of coal and fly ash were collected from different thermal power stations in northern India and cement samples from National Council for Cement and Building Materials, Ballabgarh (Haryana), India and were analysed for radon concentration. For the measurement, alpha sensitive LR-115 type II plastic track detectors were used. Based upon the available data, the annual effective dose and the lifetime fatality risk factors have been calculated. The radon concentration from coal samples varied from 433 ± 28 Bqm -3 to 2086 ± 28 Bqm -3 . The radon concentration from fly ash samples varied from 748 ± 28 Bqm -3 to 1417 ± 111 Bqm -3 and from 158 Bqm -3 to 1810 Bqm -3 in cement samples, with an average of 624 ± 169 Bqm -3 . (author)

29Si solid state NMR investigation of pozzolanic reaction occurring in lime-treated Ca-bentonite

International Nuclear Information System (INIS)

Pomakhina, Elena; Deneele, Dimitri; Gaillot, Anne-Claire; Paris, Michael; Ouvrard, Guy

2012-01-01

Lime is widely used as additive to improve the mechanical properties of natural soil used in earthworks. However, the physico-chemical mechanisms involved are yet not well understood. In order to develop and optimize this treatment method, a better understanding of the interaction between lime and the minerals of the soils, in particular clay minerals, is required. In this study, Ca-bentonite was treated with 2, 5 and 10 wt.% of lime during 1 to 98 days. Modifications in the Si local environment were then monitored by solid state nuclear magnetic resonance to investigate the pozzolanic reaction. All the soil mineral phases contribute to the release of Si and to the pozzolanic reaction, with a rapid and total consumption of Si-polymorph and an exacerbated dissolution of montmorillonite. Mechanism of C–S–H formation, function of the Ca content in the system, was found to match the sorosilicate-tobermorite model described in cement systems.

Radioactive waste cementation

International Nuclear Information System (INIS)

Soriano B, A.

1996-01-01

This research was carried out to develop the most adequate technique to immobilize low and medium-activity radioactive waste. different brands of national cement were used, portland and pozzolanic cement. Prismatic and cylindrical test tubes were prepared with different water/cement (W/C) relationship. Additives such a as clay and bentonite were added in some other cases. Later, the properties of these test tubes were evaluated. Properties such as: mechanical resistance, immersion resistance, lixiviation and porosity resistance. Cement with the highest mechanical resistance values, 62,29 MPa was pozzolanic cement for a W/C relationship of 0,35. It must be mentioned that the other types of cements reached a mechanical resistance over 10 MPa, a value indicated by the international standards for transportation and storage of low and medium-activity radioactive waste at a superficial level. However, in the case of immersion resistance, Sol cement (portland type I) with a W/C relationship of 0,35 reached a compression resistance over 61,92 MPa; as in the previous cases, the other cements reached a mechanical resistance > 10 MPa. Regarding porosity, working with W/C relationships = 0,35 0,40 and 0,45, without additives and with additives, the percentage of porosity found for all cements is lower than 40% percentage indicated by international standards. With regard to the lixiviation test, pozzolanic cement best retained Cesium-137 and Cobalt-60, and increased its advantages when bentonite was added, obtaining a lixiviation rate of 2,02 x E-6 cm/day. Sol cement also improved its properties when bentonite was added and obtained a lixiviation rate of 2,84 x E-6 cm/day for Cesium-137. However, Cobalt-60 is almost completely retained with the 3 types of cement with or without additives, reaching the limits indicated by the international standards for the lixiviation rate of beta-gamma emitter < 5,00E-4 cm/day. Characterizing the final product involves the knowledge of its

An Ice Block: A Novel Technique of Successful Prevention of Cement Leakage Using an Ice Ball

Energy Technology Data Exchange (ETDEWEB)

Uri, Ishaq Fahmi, E-mail: uri.isaac@gmail.com [The Royal National Orthopaedic Hospital (United Kingdom); Garnon, Julien, E-mail: juliengarnon@gmail.com; Tsoumakidou, Georgia, E-mail: georgia.tsoumakidou@chru-strasbourg.fr; Gangi, Afshin, E-mail: gangi@unistra.fr [Hôpital Universitaire de Strasbourg, Service d’Imagerie Interventionnelle (France)

2015-04-15

We report three cases of painful bone metastases with extraosseous invasion treated with cementoplasty and cryoablation. Due to significant cortical loss in all cases, the ice ball was used simultaneously during cementoplasty to deter potential cement leakage. This was achieved by direct application of the ice ball against the cortical surface, resulting in adequate consolidation and successful containment of the cement within the treated bones. To the authors’ knowledge, this is the first report to describe such a combined technique.

CT evaluation of local leakage of bone cement after percutaneous kyphoplasty and vertebroplasty

International Nuclear Information System (INIS)

Lee, In Jae; Choi, A. Lam; Yie, Mi-Yeon; Yoon, Ji Young; Jeon, Eui Yong; Koh, Sung Hye; Yoon, Dae Young; Lim, Kyung Ja; Im, Hyoung June

2010-01-01

Background: Percutaneous injection of bone cement (acrylic cement) during percutaneous kyphoplasty and vertebroplasty can cause symptomatic or asymptomatic complications due to leakage, extravasation or vascular migration of cement. Purpose: To investigate and to compare the incidence and site of local leakage or complications of bone cement after percutaneous kyphoplasty and vertebroplasty using bone cement. Material and Methods: We retrospectively reviewed 473 cases of percutaneous kyphoplasty or vertebroplasty performed under fluoroscopic guidance. Of the 473 cases, follow-up CT scans that covered the treated bones were available for 83 cases (59 kyphoplasty and 24 vertebroplasty). Results: The rate of local leakage of bone cement was 87.5% (21/24) for percutaneous vertebroplasty and 49.2% (29/59) for kyphoplasty. The most common site of local leakage was perivertebral soft tissue (n=8, 38.1%) for vertebroplasty. The most common site of local leakage was a perivertebral vein (n=7, 24.1%) for kyphoplasty. Two cases of pulmonary cement embolism developed: one case after kyphoplasty and one case after vertebroplasty. Conclusion: Local leakage of bone cement was more common for percutaneous vertebroplasty compared with kyphoplasty (P<0.005). The most common sites of local leakage were perivertebral soft tissue and perivertebral vein.

Uptake of selenate on hydrated and degraded cement: batch and dynamic experiments

International Nuclear Information System (INIS)

Rojo, I.; Rovira, I.; Marti, V.; Pablo, J. de; Duro, L.; Gaona, X.; Colas, E.; Grive, M.

2009-01-01

The evaluation of selenate sorption and retardation in batch and dynamic experiments on hydrated and degraded cement has been studied. Desorption studies have also been carried in order to assess the reversibility of the sorption process. Sorption data onto degraded cement have been treated assuming the formation of surface complexes, whereas sorption kinetics has been fitted by using a pseudo-first order kinetic equation. Dynamic flow experiments have also been modelled. (authors)

Influence of loading rate and modes on infiltration of treated wastewater in soil-based constructed wetland.

Science.gov (United States)

Bisone, Sara; Gautier, Mathieu; Masson, Matthieu; Forquet, Nicolas

2017-01-01

Over the last 10 years soil-based constructed wetlands for discharge of treated wastewater (TWW) are commonly presented as a valuable option to provide tertiary treatment. The uncomplete knowledge in soil modifications and a lack of clear design practices laid the foundation of this work. The aim of this study was to determine optimal hydraulic loads and to observe the main critical parameters affecting treating performances and hydraulic loads acceptance. For this purpose, a soil rich in clay and backfill was chosen to perform column infiltration tests with TWW. Two loading rates and two loading modes were compared to study the influence of an intermittent feeding. Inlet and outlet waters were periodically analysed and columns were instrumented with balances, tensiometers, O 2 and temperature probes. Soil physico-chemical characteristics were also taken into account to better understand the modification of the soil. One of the main expectations of tertiary treatment is to improve phosphate removal. A particular attention was thus given to phosphorus retention. The interest of an intermittent feeding in presence of a soil with high clay content was showed. This study highlighted that an intermittent feeding could make possible the use of a clay-rich soil for water infiltration.

Parameters of Alumina Cement and Portland Cement with Addition of Chalcedonite Meal

Science.gov (United States)

Kotwa, Anna

2017-10-01

Aluminous cement is a quick binder with special properties. It is used primarily to make non-standard monolithic components exposed to high temperatures, + 1300°C. It is also a component of adhesives and mortars. It has a very short setting time. It is characterized by rapid increase in mechanical strength and resistance to aggressive sulphates. It can be used in reinforced concrete structures. Laying of concrete, construction mortar made of alumina cement can be carried out even at temperatures of -10°C. This article discusses a comparison of the parameters of hardened mortar made of alumina cement GÓRKAL 40 and Portland cement CEM I 42.5R. The mortars contain an addition of chalcedonite meal with pozzolanic properties, with particle size of less than 0.063μm. The meal was added in amounts of 5% and 20% of cement weight. Chalcedonite meal used in the laboratory research is waste material, resulting from chalcedonite aggregate mining. It has the same properties as the rock from which it originates. We have compared the parameters of hardened mortar i.e. compressive strength, water absorption and capillarity. The addition of 20% chalcedonite meal to mortars made from aluminous cement will decrease durability by 6.1% relative to aluminous cement mortar without addition of meal. Considering the results obtained during the absorbency tests, it can be stated that the addition of chalcedonite meal reduces weight gains in mortars made with cement CEM I 42.5 R and alumina cement. Use of alumina cement without addition of meal in mortars causes an increase of mass by 248% compared to Portland cement mortars without additions, in the absorption tests. The addition of chalcedonite meal did not cause increased weight gain in the capillary action tests. For the alumina cement mortars, a lesser weight gains of 24.7% was reported, compared to the Portland cement mortar after 28 days of maturing.

Comparison between three glass fiber post cementation techniques.

Science.gov (United States)

Migliau, Guido; Piccoli, Luca; Di Carlo, Stefano; Pompa, Giorgio; Besharat, Laith Konstantinos; Dolci, Marco

2017-01-01

The aim of this experimental study was to compare the traditional cement systems with those of the latest generation, to assess if indeed these could represent of viable substitutes in the cementation of indirect restorations, and in the specific case of endodontic posts. The assessment of the validity of the cementing methods was performed according to the test of the push-out, conducted on sections obtained from the roots of treated teeth. The samples were divided into three groups. Group A (10 samples): etching for 30 seconds with 37% orthophosphoric acid (Superlux-Thixo-etch-DMG) combined with a dual-curing adhesive system (LuxaBond-Total Etch-DMG), dual-cured resin-composite cement (LuxaCore-DMG) and glass fiber posts (LuxaPost-DMG). Group B (10 samples): self-adhesive resin cement (Breeze-Pentron Clinical) and glass fiber posts (LuxaPost-DMG). Group C (10 samples): 3 steps light-curing, self-etching, self-conditioning bonding agent (Contax-Total-etch-DMG), dual-cured resin-composite cement (LuxaCore-DMG) and glass fiber posts (LuxaPost-DMG). The survey was conducted by examining the breaking resistance of the post-cement-tooth complex, subjected to a mechanical force. Statistical analysis was performed using SPSS Inc. ver. 13.0, Chicago, IL, USA. Group A values of bond strenth ranged from a minimum of 10.14 Mpa to a maximum value of 14.73 Mpa with a mean value of 12.58 Mpa. In Group B the highest value of bond strength was 6.54 Mpa and the minimum 5.55 Mpa. The mean value of the bond strength for the entire group was 6.58 Mpa. In Group C the highest bond strength was 6.59 Mpa whereas the lowest bond strength was 4.84 Mpa. Mean value of the bond strength of Group C was calculated at 5.7 Mpa. Etching with orthophosphoric acid combined with a dual-curing adhesive system and a dual-cured resin-composite cement was the technique that guaranteed the highest bond strength. Lowest bond strength values were obtained when dual self-adhesive cement was used.

Long-term soil accumulation of chromium, copper, and arsenic adjacent to preservative-treated wood.

Science.gov (United States)

S. Lebow; D. Foster; J. Evans

2004-01-01

Chromated copper arsenate (CCA) treated wood has been used extensively in outdoor applications. The Environmental Protection Agency (EPA) and CCA producers recently reached an agreement to limit future use of CCA for some types of applications. One area of concern is the long-term accumulation of leached CCA in soil adjacent to treated wood structures. Interpreting...

Role of wetting and drying cycles in formation and growth of soil aggregates

Science.gov (United States)

Ghezzehei, T. A.; Lopez, J. P.

2009-12-01

Soil structure directly determines important soil physical properties including porosity, hydraulic conductivity, water retention, and mechanical strength and indirectly influences most biological and chemical processes that occur in and around soil. In response to the various processes that occur within it, soil structure evolves continuously at multiple spatial and temporal scales. We hypothesize that the rhythm of the evolution is controlled by wetting and drying cycles. Here, we will present a mathematical description of the role of wetting and drying cycles in the formation and stabilization of soil aggregates with emphasis on two important roles of wetting and drying cycles: (1) transport and deposition of organic and inorganic cementing agents at the most effective locations, (2) chemical and physical alteration of cementing agents during desiccation and the resultant semi-permanent bonding (or bond hardening). Our results demonstrate that size and strength of aggregates are determined by particle size, degree of dryness, number of wetting-drying cycles, as well as concentration and solubility of dissolved and/or colloidal cementing agents. These results are in general agreement with experimental observations obtained from the literature.

Evaluating the applicability of regulatory leaching tests for assessing the hazards of Pb-contaminated soils.

Science.gov (United States)

Halim, Cheryl E; Scott, Jason A; Amal, Rose; Short, Stephen A; Beydoun, Donia; Low, Gary; Cattle, Julie

2005-04-11

Soil contamination is a major environmental problem due to the ecological threat it poses. In this work, electron probe microanalysis (EPMA), X-ray diffraction (XRD), and leaching studies were employed to explain the different leaching behaviors of non-stabilized and stabilized soils. The applicability of the leaching fluids used in the toxicity characteristic leaching procedure (TCLP) and Australian Standards, AS 4439.1-1997 for assessing the hazards of contaminated soils was investigated as was the leaching of lead from soil stabilized by cement and buffered phosphate techniques. The results showed Pb speciation in the soil highly influenced metal leaching. The synthetic leaching fluids were unable to provide a reliable estimation of Pb concentration in the municipal landfill leachate (ML) due to the absence of organic ligands capable of forming stable complexes with the lead. Water provided the closest representation of lead leaching from the non-stabilized and phosphate stabilized soils while sodium tetraborate buffer was found to be suitable for cement-stabilized soil in a non-putrescible landfill leachate system. A comparison of stabilization methods revealed that the buffered phosphate technique was more suitable for stabilizing the lead in the soil relative to cement stabilization.

Evaluating the applicability of regulatory leaching tests for assessing the hazards of Pb-contaminated soils

International Nuclear Information System (INIS)

Halim, Cheryl E.; Scott, Jason A.; Amal, Rose; Short, Stephen A.; Beydoun, Donia; Low, Gary; Cattle, Julie

2005-01-01

Soil contamination is a major environmental problem due to the ecological threat it poses. In this work, electron probe microanalysis (EPMA), X-ray diffraction (XRD), and leaching studies were employed to explain the different leaching behaviors of non-stabilized and stabilized soils. The applicability of the leaching fluids used in the toxicity characteristic leaching procedure (TCLP) and Australian Standards, AS 4439.1-1997 for assessing the hazards of contaminated soils was investigated as was the leaching of lead from soil stabilized by cement and buffered phosphate techniques. The results showed Pb speciation in the soil highly influenced metal leaching. The synthetic leaching fluids were unable to provide a reliable estimation of Pb concentration in the municipal landfill leachate (ML) due to the absence of organic ligands capable of forming stable complexes with the lead. Water provided the closest representation of lead leaching from the non-stabilized and phosphate stabilized soils while sodium tetraborate buffer was found to be suitable for cement-stabilized soil in a non-putrescible landfill leachate system. A comparison of stabilization methods revealed that the buffered phosphate technique was more suitable for stabilizing the lead in the soil relative to cement stabilization

In-place cement stabilized base reconstruction techniques interim report : "construction and two year evaluation".

Science.gov (United States)

2002-08-01

The purpose of this research was to evaluate the effectiveness of soil cement shrinkage crack mitigation techniques. The contents of this report reflect an evaluation of the construction of the test sections and a two-year evaluation of the test sect...

Superfund Innovative Technology Evaluation - Demonstration Bulletin: In-Situ Soil Stabilization

Science.gov (United States)

In-situ stabilization technology immobilizes organics and inorganic compounds in wet or dry soils by using reagents (additives) to polymerize with the soils and sludges producing a cement-like mass. Two basic components of this technology are the Geo-Con/DSM Deep Soil Mixing Sy...

Transformation of organic N newly added to red soil treated with different cultural practices

Institute of Scientific and Technical Information of China (English)

ZhangQin－Zheng; YeQing－Fu; 等

1998-01-01

By using 15N tracer method,transformation of organic N,which wqas newly added to red soil treated with different cultural practices,was studied under thelaboratory incubation condition.The experimental results showed that the transformation of N from newly added organic matter and soil native pool during incubation was influenced by cultural practice treatment beforeincubation.Fallow was favorable to the mineralization of newly added organic N and soil N compared with the planting wheat treatment.Planting wheat greatly increased the loss of soil N.Application of fertilizers stimulated the mineralization of newly added organic N and application of organic matter reduced the mineralization,but stimulated microbialtransformation of newly adde4d organic N.

Use of Incineration Solid Waste Bottom Ash as Cement Mixture in Cement Production

Science.gov (United States)

Jun, N. H.; Abdullah, M. M. A. B.; Jin, T. S.; Kadir, A. A.; Tugui, C. A.; Sandu, A. V.

2017-06-01

Incineration solid waste bottom ash was use to examine the suitability as a substitution in cement production. This study enveloped an innovative technology option for designing new equivalent cement that contains incineration solid waste bottom ash. The compressive strength of the samples was determined at 7, 14, 28 and 90 days. The result was compared to control cement with cement mixture containing incineration waste bottom ash where the result proved that bottom ash cement mixture able achieve its equivalent performance compared to control cement which meeting the requirement of the standards according to EN 196-1. The pozzolanic activity index of bottom ash cement mixture reached 0.92 at 28 days and 0.95 at 90 and this values can be concluded as a pozzolanic material with positive pozzolanic activity. Calcium hydroxide in Portland cement decreasing with the increasing replacement of bottom ash where the reaction occur between Ca(OH)2 and active SiO2.

Development of Self-Consolidating High Strength Concrete Incorporating Treated Palm Oil Fuel Ash

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Belal Alsubari

2015-04-01

Full Text Available Palm oil fuel ash (POFA has previously been used as a partial cement replacement in concrete. However, limited research has been undertaken to utilize POFA in high volume in concrete. This paper presents a study on the treatment and utilization of POFA in high volume of up to 50% by weight of cement in self-consolidating high strength concrete (SCHSC. POFA was treated via heat treatment to reduce the content of unburned carbon. Ordinary Portland cement was substituted with 0%, 10%, 20%, 30%, and 50% treated POFA in SCHSC. Tests have been conducted on the fresh properties, such as filling ability, passing ability and segregation resistance, as well as compressive strength, drying shrinkage and acid attack resistance to check the effect of high volume treated POFA on SCHSC. The results revealed that compared to the control concrete mix, the fresh properties, compressive strength, drying shrinkage, and resistance against acid attack have been significantly improved. Conclusively, treated POFA can be used in high volume as a cement replacement to produce SCHSC with an improvement in its properties.

Development of Self-Consolidating High Strength Concrete Incorporating Treated Palm Oil Fuel Ash

Science.gov (United States)

Alsubari, Belal; Shafigh, Payam; Jumaat, Mohd Zamin

2015-01-01

Palm oil fuel ash (POFA) has previously been used as a partial cement replacement in concrete. However, limited research has been undertaken to utilize POFA in high volume in concrete. This paper presents a study on the treatment and utilization of POFA in high volume of up to 50% by weight of cement in self-consolidating high strength concrete (SCHSC). POFA was treated via heat treatment to reduce the content of unburned carbon. Ordinary Portland cement was substituted with 0%, 10%, 20%, 30%, and 50% treated POFA in SCHSC. Tests have been conducted on the fresh properties, such as filling ability, passing ability and segregation resistance, as well as compressive strength, drying shrinkage and acid attack resistance to check the effect of high volume treated POFA on SCHSC. The results revealed that compared to the control concrete mix, the fresh properties, compressive strength, drying shrinkage, and resistance against acid attack have been significantly improved. Conclusively, treated POFA can be used in high volume as a cement replacement to produce SCHSC with an improvement in its properties.

Detecting Poor Cement Bonding and Zonal Isolation Problems Using Magnetic Cement Slurries

KAUST Repository

Nair, Sriramya D.; Patzek, Tadeusz; van Oort, Eric

2017-01-01

There has been growing interest in the use of magnetorheological fluids to improve displacement efficiency of fluids (drilling fluids, spacer fluids, cement slurries) in the eccentric casing annuli. When magnetic particles are mixed with the cement slurry for improved displacement, they provide an excellent opportunity for sensing the presence and quality of cement in the annulus. This work focuses on using sophisticated 3D computational electromagnetics to simulate the use of a magnetic cement slurry for well cement monitoring. The main goal is to develop a new tool, which is capable of locating magnetic cement slurry that is placed behind a stainless steel casing. An electromagnetic coil was used to generate a magnetic field inside the borehole. It was found that when a current was passed through the electric coils, magnetic field lines passed through the stainless steel casing, the cement annulus and the rock formation. Three sensors were placed inside the cased borehole and the magnetic field strength variations were observed at these locations. Various factors that have a significant influence on zonal isolation were considered. These include, effect of debonding between casing and cement annulus, effect of changing annuli thickness, influence of a fracture in the rock formation, effect of changing magnetic permeability of cement and finally influence of annuli eccentricity. Based on the results shown in the paper along with the next generation of supersensitive magnetic sensors that are being developed, the magnetic approach appears to be a viable alternative for evaluating the quality of the cement annulus to ensure good zonal isolation.

Detecting Poor Cement Bonding and Zonal Isolation Problems Using Magnetic Cement Slurries

KAUST Repository

Nair, Sriramya D.

2017-10-02

There has been growing interest in the use of magnetorheological fluids to improve displacement efficiency of fluids (drilling fluids, spacer fluids, cement slurries) in the eccentric casing annuli. When magnetic particles are mixed with the cement slurry for improved displacement, they provide an excellent opportunity for sensing the presence and quality of cement in the annulus. This work focuses on using sophisticated 3D computational electromagnetics to simulate the use of a magnetic cement slurry for well cement monitoring. The main goal is to develop a new tool, which is capable of locating magnetic cement slurry that is placed behind a stainless steel casing. An electromagnetic coil was used to generate a magnetic field inside the borehole. It was found that when a current was passed through the electric coils, magnetic field lines passed through the stainless steel casing, the cement annulus and the rock formation. Three sensors were placed inside the cased borehole and the magnetic field strength variations were observed at these locations. Various factors that have a significant influence on zonal isolation were considered. These include, effect of debonding between casing and cement annulus, effect of changing annuli thickness, influence of a fracture in the rock formation, effect of changing magnetic permeability of cement and finally influence of annuli eccentricity. Based on the results shown in the paper along with the next generation of supersensitive magnetic sensors that are being developed, the magnetic approach appears to be a viable alternative for evaluating the quality of the cement annulus to ensure good zonal isolation.

[Correlation analysis of cement leakage with volume ratio of intravertebral bone cement to vertebral body and vertebral body wall incompetence in percutaneous vertebroplasty for osteoporotic vertebral compression fractures].

Science.gov (United States)

Liang, De; Ye, Linqiang; Jiang, Xiaobing; Huang, Weiquan; Yao, Zhensong; Tang, Yongchao; Zhang, Shuncong; Jin, Daxiang

2014-11-01

To investigate the risk factors of cement leakage in percutaneous vertebroplasty (PVP) for osteoporotic vertebral compression fracture (OVCF). Between March 2011 and March 2012, 98 patients with single level OVCF were treated by PVP, and the clinical data were analyzed retrospectively. There were 13 males and 85 females, with a mean age of 77.2 years (range, 54-95 years). The mean disease duration was 43 days (range, 15-120 days), and the mean T score of bone mineral density (BMD) was -3.8 (range, -6.7- -2.5). Bilateral transpedicular approach was used in all the patients. The patients were divided into cement leakage group and no cement leakage group by occurrence of cement leakage based on postoperative CT. Single factor analysis was used to analyze the difference between 2 groups in T score of BMD, operative level, preoperative anterior compression degree of operative vertebrae, preoperative middle compression degree of operative vertebrae, preoperative sagittal Cobb angle of operative vertebrae, preoperative vertebral body wall incompetence, cement volume, and volume ratio of intravertebral bone cement to vertebral body. All relevant factors were introduced to logistic regression analysis to analyze the risk factors of cement leakage. All procedures were performed successfully. The mean operation time was 40 minutes (range, 30-50 minutes), and the mean volume ratio of intravertebral bone cement to vertebral body was 24.88% (range, 7.84%-38.99%). Back pain was alleviated significantly in all the patients postoperatively. All patients were followed up with a mean time of 8 months (range, 6-12 months). Cement leakage occurred in 49 patients. Single factor analysis showed that there were significant differences in the volume ratio of intravertebral bone cement to vertebral body and preoperative vertebral body wall incompetence between 2 groups (P 0.05). The logistic regression analysis showed that the volume ratio of intravertebral bone cement to vertebral body (P

Tritium transport in subsurface soil and its retentivity in cement waste forms

International Nuclear Information System (INIS)

Varghese, C.; Khan, Z.A.

1990-01-01

Tritiated aqueous wastes generated from power reactors and reprocessing plants need fixation and containment in solid media. Incorporating tritium in inorganic hydrates like cement retards its movements substantially. Naturally occurring clay mineral like vermiculite which has high water holding capacity was used as a filler material. To improve the retention of tritium in the cement blocks, certain coating materials were used after curing the blocks for 28 days. Long time leach tests for these barrier incorporated wastes forms have shown tritium releases of 17% loaded tritium over a period of 97 days. But the selected coating reduced it to 0.9%. Investigations on the movements of tritium at Tarapur and Narora revealed that in the unsaturated zone, tritium percolation was low, whereas in the saturated zone, it was found to travel with higher velocities, limiting to ground water movement. (author). 5 refs., 3 tabs

The cement recycling of the earthquake disaster debris by Hachinohe Cement Co., Ltd

International Nuclear Information System (INIS)

Kataoka, Masayuki

2015-01-01

A tremendous quantity of earthquake disaster debris and tsunami sediment was resulted by the Great East Japan Earthquake on March 11, 2011. Hachinohe Cement Co., Ltd., a Sumitomo Osaka Cement subsidiary, was the first cement industry company to receive and process such waste materials outside of their usual prefecture area, while the company is performing their treatment and recycling services locally in Hachinohe City and Aomori Prefecture. This report provides an explanation about the recycling mechanism of waste materials and by-products in cement manufacturing process, and introduces an example of actual achievements for the disaster debris treatment by utilizing the cement recycling technologies at the Hachinohe Cement Plant. (author)

Effect of Cement Type on Autogenous Deformation of Cement-Based Materials

DEFF Research Database (Denmark)

Pietro, Lura; Ye, Guang; van Breugel, Klaas

2004-01-01

In this paper, measurements of non-evaporable water content, chemical shrinkage, autogenous deformation, internal relative humidity (RH), pore solution composition, and early-age elastic modulus are presented and discussed. All experiments were performed on Portland cement and blast-furnace slag...... (BFS) cement pastes. Self-desiccation shrinkage of the BFS cement paste was modeled based on the RH measurements, following the capillary-tension approach. The main findings of this study are: 1) self-desiccation shrinkage can be related to self-desiccation both for Portland and for BFS cement pastes......, taking into account the influence of the dissolved salts in the pore solution, 2) the BFS cement paste studied shows pronounced self-desiccation and self-desiccation shrinkage, mainly caused by its very fine pore structure....

Influence of Thermal Treatment Conditions on the Properties of Dental Silicate Cements

Directory of Open Access Journals (Sweden)

Georgeta Voicu

2016-02-01

Full Text Available In this study the sol-gel process was used to synthesize a precursor mixture for the preparation of silicate cement, also called mineral trioxide aggregate (MTA cement. This mixture was thermally treated under two different conditions (1400 °C/2 h and 1450 °C/3 h followed by rapid cooling in air. The resulted material (clinker was ground for one hour in a laboratory planetary mill (v = 150 rot/min, in order to obtain the MTA cements. The setting time and mechanical properties, in vitro induction of apatite formation by soaking in simulated body fluid (SBF and cytocompatibility of the MTA cements were assessed in this study. The hardening processes, nature of the reaction products and the microstructural characteristics were also investigated. The anhydrous and hydrated cements were characterized by different techniques e.g., X-ray diffraction (XRD, scanning electron microscopy (SEM, infrared spectroscopy (FT-IR and thermal analysis (DTA-DTG-TG. The setting time of the MTA cement obtained by thermal treatment at 1400 °C/2 h (MTA1 was 55 min and 15 min for the MTA cement obtained at 1450 °C/3 h (MTA2. The compressive strength values were 18.5 MPa (MTA1 and 22.9 MPa (MTA2. Both MTA cements showed good bioactivity (assessed by an in vitro test, good cytocompatibility and stimulatory effect on the proliferation of cells.

Experimental study on the solidification and influence factors of MSW stabilized soil

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Wang Zhiping

2015-01-01

Full Text Available The effect of kinds and dosage of curing agent on the curing effect and strength characteristics of municipal solid waste (MSW stabilized soil is very obvious. In order to reveal these effects, this paper uses cement, fly ash, lime and gypsum as main curing agent and additives to make MSW stabilized soil samples of different components and contents and its strength is obtained using unconfined compressive strength test. The results showed that the curing age, dosage of cement, fly ash, lime and gypsum have effect on the strengths of stabilized MSW soil. The bigger the content of cement and fly ash, the higher the strength of stabilized soil. But the amount of lime and gypsum has a critical value. Within the critical value, the strength of the stabilized soil increases with the increasing of the content of the additives, and decreases with the increase of the additives content if the content of the additives exceeds the critical value. The curing age has much effect on the strength of the stabilized soil. The strength of the samples for 7 days is far less than that for 28 days. This can be explained that: when the curing agent is added into the stabilized soil, the connection among the particles of the MSW soil is changed from weak connection to bond connection, and therefore the strength of the curing MSW soil is improved.

Effects of domestic wastewater treated by anaerobic stabilization on soil pollution, plant nutrition, and cotton crop yield.

Science.gov (United States)

Uzen, Nese; Cetin, Oner; Unlu, Mustafa

2016-12-01

This study has aimed to determine the effects of treated wastewater on cotton yield and soil pollution in Southeastern Anatolia Region of Turkey during 2011 and 2012. The treated wastewater was provided from the reservoir operated as anaerobic stabilization. After treatment, suspended solids (28-60 mg/l), biological oxygen demand (29-30 mg/l), and chemical oxygen demand (71-112 mg/l) decreased significantly compared to those in the wastewater. There was no heavy metal pollution in the water used. There were no significant amounts of coliform bacteria, fecal coliform, and Escherichia coli compared to untreated wastewater. The cottonseed yield (31.8 g/plant) in the tanks where no commercial fertilizers were applied was considerably higher compared to the yield (17.2 g/plant) in the fertilized tanks where a common nitrogenous fertilizer was utilized. There were no significant differences between the values of soil pH. Soil electrical conductivity (EC) after the experiment increased from 0.8-1.0 to 0.9-1.8 dS/m. Heavy metal pollution did not occur in the soil and plants, because there were no heavy metals in the treated wastewater. It can be concluded that treated domestic wastewater could be used to grow in a controlled manner crops, such as cotton, that would not be used directly as human nutrients.

Crumb waste tire rubber surface modification by plasma polymerization of ethanol and its application on oil-well cement

Energy Technology Data Exchange (ETDEWEB)

Xiaowei, Cheng [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu (China); School of Material Science and Engineering, Southwest Petroleum University, Chengdu (China); Sheng, Huang [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu (China); School of Oil and Natural Gas Engineering, Southwest Petroleum University, Chengdu (China); Xiaoyang, Guo, E-mail: guoxiaoyangswpi@126.com [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu (China); School of Oil and Natural Gas Engineering, Southwest Petroleum University, Chengdu (China); Wenhui, Duan, E-mail: wenhui.duan@monash.edu [Department of Civil Engineering, Monash University, Clayton, Melbourne 3800 (Australia)

2017-07-01

Highlights: • The crumb waste tire rubber (WTR) was modified by plasma polymerization of ethanol. • Hydrophilic groups were introduced onto WTR surface and improved its hydrophilia. • The functionalized crumb WTR was applied in oil-well cement. • The mechanical properties of modified oil-well cement were intensively enhanced. - Abstract: Crumb waste tire rubber (WTR) was pretreated by oxygen low temperature plasma (LTP) and modified by LTP polymerization process of ethanol monomer to improve the adhesion property with oil-well cement matrix and the mechanical properties of cement. The surface properties of modified crumb WTR and the mechanical properties and structures of modified oil-well cement were investigated by means of contact angle measurement, dispersion test, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), mechanics performance tests, permeability test and scanning electron microscopy (SEM). It was demonstrated that LTP treatment changed both the surface composition and roughness. The contact angle of pretreated crumb WTR dramatically fell from 122° to 34°, and sample with ethanol LPT polymer film decreased even further to 11°. The ATR-FTIR and XPS analysis results demonstrated that hydrophilic groups, such as –COOH, C–OH, and –CHO, were introduced on the WTR surface. The oxygen atomic percent increased from 8.11% to 14.50% and 24.83%. The mechanical properties, porosity and permeability of raw cement were compared to samples modified by untreated crumb WTR, pretreated crumb WTR and ethanol LTP polymerization treated crumb WTR. It was found that after 28 days, the compressive strength of the samples with the untreated crumb WTR decreased to 80% with respect to raw cement. The tensile strength and flexural strength also had a slight reduction compared with the raw cement. On the contrary, after 28 days, the tensile strength of cement modified by LTP polymerization

Crumb waste tire rubber surface modification by plasma polymerization of ethanol and its application on oil-well cement

International Nuclear Information System (INIS)

Xiaowei, Cheng; Sheng, Huang; Xiaoyang, Guo; Wenhui, Duan

2017-01-01

Highlights: • The crumb waste tire rubber (WTR) was modified by plasma polymerization of ethanol. • Hydrophilic groups were introduced onto WTR surface and improved its hydrophilia. • The functionalized crumb WTR was applied in oil-well cement. • The mechanical properties of modified oil-well cement were intensively enhanced. - Abstract: Crumb waste tire rubber (WTR) was pretreated by oxygen low temperature plasma (LTP) and modified by LTP polymerization process of ethanol monomer to improve the adhesion property with oil-well cement matrix and the mechanical properties of cement. The surface properties of modified crumb WTR and the mechanical properties and structures of modified oil-well cement were investigated by means of contact angle measurement, dispersion test, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), mechanics performance tests, permeability test and scanning electron microscopy (SEM). It was demonstrated that LTP treatment changed both the surface composition and roughness. The contact angle of pretreated crumb WTR dramatically fell from 122° to 34°, and sample with ethanol LPT polymer film decreased even further to 11°. The ATR-FTIR and XPS analysis results demonstrated that hydrophilic groups, such as –COOH, C–OH, and –CHO, were introduced on the WTR surface. The oxygen atomic percent increased from 8.11% to 14.50% and 24.83%. The mechanical properties, porosity and permeability of raw cement were compared to samples modified by untreated crumb WTR, pretreated crumb WTR and ethanol LTP polymerization treated crumb WTR. It was found that after 28 days, the compressive strength of the samples with the untreated crumb WTR decreased to 80% with respect to raw cement. The tensile strength and flexural strength also had a slight reduction compared with the raw cement. On the contrary, after 28 days, the tensile strength of cement modified by LTP polymerization

Foamed cement for squeeze cementing low-pressure, highly permeable reservoirs

International Nuclear Information System (INIS)

Chmllowski, W.; Kondratoff, L.B.

1992-01-01

Four different cement squeezing techniques have been used on wells producing from the Keg River formation in the Rainbow Lake area of Alberta, Canada. This paper evaluates 151 cement squeeze treatments performed at 96 wellsites and compares the use of foam cement vs. conventional squeeze treatments and techniques. Discussion includes key aspects, such as candidate selection, slurry design, treatment design, economic evaluation, and operational considerations

FEASIBILITY ANALYSIS ON INDUSTRIAL SYMBIOSIS BETWEEN CEMENT INDUSTRY AND TEA INDUSTRY

Directory of Open Access Journals (Sweden)

Shailendra Kumar Yadav

2015-08-01

Full Text Available The project aims at analyzing the feasibility of utilizing cement kiln dust (CKD in treating wastewater from tea industry with the concept of industrial symbiosis. CKD is the dust collected at the air pollution control device(s associated with a kiln system from cement industry. A very less percent of CKD is recycled and the rest is land filled /stockpiled; disrupts groundwater through leaching of minerals. Cement Kiln Dust (CKD, rich in CaO, SiO2, behaves as a neutralizing as well as stabilizing agent for tea effluent treatment. The ability of CKD to reduce the BOD, COD, TSS, and phosphates in tea effluent was analyzed and the optimum dosage is determined. The effect of different dosages of Cement Kiln Dust ranging from (1-3 gm/l has been discussed on the bench scale tests. The results show that, for different CKD concentrations, high removal efficiencies of 94.4 and 99.0, 58.9 for BOD, TSS, phosphates and a lower efficiency for COD with 9.09 are achieved for 2.5gm/l. The persistent presence of color providing proteins theaflavins (TF and the arubigins (TR from the leftover tea leaves in the effluent imparts the low removal efficiencies of COD. However, the COD value is within the dischargeable limits (CPCB standards. Moreover, a considerable removal efficiency and high SVI of 0.181 makes CKD a feasible coagulant in treating tea effluent with optimum dosage of 2.5g/l. The objective of developing industrial symbiosis network was thus achieved using the CKD to treat wastewater from tea industries.   International Journal of EnvironmentVolume-4, Issue-3, June-August 2015Page: 20-34

Percutaneous Extraction of Cement Leakage After Vertebroplasty Under CT and Fluoroscopy Guidance: A New Technique

International Nuclear Information System (INIS)

Amoretti, Nicolas; Huwart, Laurent

2012-01-01

Purpose: We report a new minimally invasive technique of extraction of cement leakage following percutaneous vertebroplasty in adults. Methods: Seven adult patients (five women, two men; mean age: 81 years) treated for vertebral compression fractures by percutaneous vertebroplasty had cement leakage into perivertebral soft tissues along the needle route. Immediately after vertebroplasty, the procedure of extraction was performed under computed tomography (CT) and fluoroscopy guidance: a Chiba needle was first inserted using the same route as the vertebroplasty until contact was obtained with the cement fragment. This needle was then used as a guide for an 11-gauge Trocar t’am (Thiebaud, France). After needle withdrawal, a 13-gauge endoscopy clamp was inserted through the cannula to extract the cement fragments. The whole procedure was performed under local anesthesia. Results: In each patient, all cement fragments were withdrawn within 10 min, without complication. Conclusions: This report suggests that this CT- and fluoroscopy-guided percutaneous technique of extraction could reduce the rate of cement leakage-related complications.

Effects of Hybrid Coat on shear bond strength of five cements: an in vitro study.

Science.gov (United States)

Guo, Yue; Zhou, Hou-De; Feng, Yun-Zhi

2017-12-01

To evaluate the sealing performance of Hybrid Coat and its influence on the shear bond strength of five dentin surface cements. Six premolars were pretreated to expose the dentin surface prior to the application of Hybrid Coat. The microscopic characteristics of the dentinal surfaces were examined with scanning electron microscopy (SEM). Then, 40 premolars were sectioned longitudinally, and 80 semi-sections were divided into a control group (untreated) and a study group (treated by Hybrid Coat). Alloy restoration was bonded to the teeth specimen using five different cements. Shear bond strength was measured by the universal testing machine. The fracture patterns and the adhesive interface were observed using astereomicroscope. SEM revealed that the lumens of dentinal tubules were completely occluded by Hybrid Coat. The Hybrid Coat significantly improved the shear bond strength of resin-modified glass ionomer cement (RMGIC) and resin cement (RC) but weakened the performance of zinc phosphate cement (ZPC), zinc polycarboxylate cement (ZPCC) and glass ionomer cement (GIC). Hybrid Coat is an effective dentinal tubule sealant, and therefore its combined use with resin or resin-modified glass ionomer cements can be applied for the prostheses attachment purpose.

Root perforations treatment using mineral trioxide aggregate and Portland cements.

Science.gov (United States)

Silva Neto, José Dias da; Brito, Rafael Horácio de; Schnaider, Taylor Brandão; Gragnani, Alfredo; Engelman, Mírian; Ferreira, Lydia Masako

2010-12-01

Clinical, radiological and histological evaluation of root perforations treated with mineral trioxide aggregate (MTA) or Portland cements, and calcium sulfate barrier. One molar and 11 premolar teeth of a male mongrel dog received endodontic treatment and furcations were perforated with a high-speed round bur and treated with a calcium sulfate barrier. MTA, Portland cement type II (PCII) and type V (PCV), and white Portland cement (WPC) were used as obturation materials. The teeth were restored with composite resin and periapical radiographs were taken. The animal was euthanized 120 days post-surgery for treatment evaluation. Right lower first premolar (MTA), right lower third premolar (PCV), left lower second premolar (MTA), and right lower second premolar (WPC): clinically normal, slightly radio-transparent area on the furcation, little inflammatory infiltrate, and new-bone formation. Left lower third premolar (PCII), right upper first premolar (WPC), right upper third premolar (PCII), and left upper first molar (PCV): clinically normal, radiopaque area on the furcation, and new-bone formation. Right upper second premolar (MTA), left upper second premolar (WPC), left upper third premolar (PCII): presence of furcation lesion, large radiolucent area, and intense inflammatory infiltrate. All obturation materials used in this study induced new-bone formation.

Effect of untreated and treated sewage wastewater by chloride or irradiation on growth of some plants and soil characteristics

International Nuclear Information System (INIS)

Takriti, S.; Khalifa, K.

2003-12-01

Pot experiments were conducted at Deir-Alhajar research station, about 40 km. south east of Damascus during 2000. Corn. eggplant and parsley were planted in plastic pots capacity 8 kg soil to study the effect of irrigation of corn, eggplant and parsley by untreated and treated sewage water (by Chloride or Irradiation) on growth and effect of irrigation on soil characteristics and accumulation of some heavy metals such as Pb, Cr, Co, Hg, and Zn, Cu in plant and soil which irrigated with treated and untreated sewage water compared with irrigated with fresh water (well water). The results showed that no negative effect was observed for untreated and treated sewage water on growth of plants (corn, eggplant and parsley). Also, no significant effect due to irrigation with treated and untreated sewage water was observed in accumulation of some trace elopements (heavy metals) such as Cr, Pb, Hg, and Zn and Cu in plants irrigated with treated and untreated sewage water to critical toxic point. This point needed more studies and longer period to confirm these results before using by farmers on large scale. Irradiation of sewage water had a positive effect on reducing the transfer of some heavy toxic metals such as Pb and Cr form waste water to soil. (author)

Influence of glass particle size of resin cements on bonding to glass ceramic: SEM and bond strength evaluation.

Science.gov (United States)

Valentini, Fernanda; Moraes, Rafael R; Pereira-Cenci, Tatiana; Boscato, Noéli

2014-05-01

This study investigated the effect of the filler particle size (micron or submicron) of experimental resin cements on the microtensile bond strength to a glass-ceramic pretreated with hydrofluoric acid (HFA) etching or alumina airborne-particle abrasion (AA). Cements were obtained from a Bis-GMA/TEGDMA mixture filled with 60 mass% micron-sized (1 ± 0.2 µm) or submicron-sized (180 ± 30 µm) Ba-Si-Al glass particles. Ceramic blocks (PM9; VITA) were treated with 10% HFA for 60 s or AA for 15 s. Silane and adhesive were applied. Ceramic blocks were bonded to resin composite blocks (Z250; 3M ESPE) using one of the cements. Bonded specimens were sectioned into beams (n = 20/group) and subjected to microtensile bond strength tests. Data were analyzed using ANOVA and Student-Newman-Keuls' tests (5%). Failure modes were classified under magnification. Morphologies of the treated ceramic surfaces and bonded interfaces were evaluated by scanning electron microscopy. The HFA-submicron group had lower bond strengths than the other groups. All AA-submicron specimens debonded prematurely. Mixed failures were predominant for HFA groups, whereas interfacial failures predominated for AA groups. SEM revealed a honeycomb-like aspect in the HFA-treated ceramic, whereas the AA-treated groups showed an irregular retentive pattern. Continuity of cement infiltration along the bonded interface was more uniform for HFA-treated compared to AA-treated specimens. Cracks toward the bulk of the ceramic were observed in AA-treated specimens. Particle size significantly influenced the ceramic bond strength, whereas surface treatment had a minor effect. Copyright © 2014 Wiley Periodicals, Inc.

Effect of cement dosage and early curing towards Kuala Perlis dredged marine sediments: a ɛv - σv and SEM-EDX approach

Science.gov (United States)

Syakeera Nordin, Nurul; Chan, Chee-Ming

2017-11-01

Cement is the primary material used in solidifying the soft soils. This material was applied in solidifying Kuala Perlis dredged marine sediments (DMS). These unwanted sediments are classified as high plasticity silt, MH with 3.36 LL of wc/LL value. At dosage 10 and 20 % of cemented-DMS and 3 days curing time, compression curve results shows the settlement criteria were enhanced than the natural DMS. Unfortunately, the settlement criteria are not complies with the permissible settlement limit and applicable pressure. The formation of cementing compounds appears in the SEM micrograph for 10 and 20 % of cemented-DMS. EDX analysis shows the Ca:Si ratio were increased for cemented-DMS due to the formation of C-S-H gel.

The influence of cement type and temperature on chloride binding in cement paste

DEFF Research Database (Denmark)

Jensen, Ole Mejlhede; Korzen, Migge Sofie Hoffmann; Skibsted, Jørgen

1998-01-01

This paper describes effects of cement type and temperature on chloride binding in cement paste, which is an important subject in relation to life-time modelling of reinforced concrete structures. The influence of cement type on chloride binding is investigated by substituting cement with pure...... cement clinker. Both theoretical considerations and experimental data for chloride binding in cement pastes are presented. A physico-chemically based model to describe the influence of temperature on physical binding of chloride is presented. Solid-state 27Al and 29Si magic-angle spinning (MAS) nuclear...... magnetic resonance (NMR) spectroscopy has been used for quantification of the anhydrous and hydrated aluminate and silicate phases in the chloride exposed cement pastes. The 27Al isotropic chemical shift and nuclear quadrupole coupling is reported for a synthetic sample of Friedel's salt, Ca2Al(OH)6Cl×2H2O....

Kinetic modeling of cement slurry synthesized with Henna extract in oil well acidizing treatments

Directory of Open Access Journals (Sweden)

Amir Hossein Aghajafari

2016-06-01

Full Text Available Acidizing treatment in petroleum reservoirs is a short-term and viable strategy to preserve the productivity of a well. There is a major concern for the degradation of cement sheath integrity, leading to poor zonal isolation and environmental issues. Therefore, it is essential to understand how the cement behaves when attacked by hydrochloric acid. In this study, a cement slurry by incorporation of the Henna extract, as an environmentally friendly cement additive, was synthesized as a potential solution to solve this problem. The characteristics of the treated cement slurry were compared with a reference slurry (w/c = 0.44 which is composed of only cement and water. A kinetic study was carried out to evaluate the adsorption behavior of the cement slurries exposed to an acid solution with 0.1 M HCl in a range of 25 to 55 °C conditions. The features of the cement slurries were evaluated by multiple analytical techniques such as XRD, FTIR, TG, and DSC analysis. From the experimental data, it is concluded that the second-order Lagergren kinetic model revealed to be the best in describing kinetic isotherms taken, because the margin between experimental and calculated values was minor for this model. The results of the characterization and HCl interaction kinetic studies underlined the prominent protective role of Henna extract-modified cement slurry in the enhancement of the cement resistance against acid attack and utilization in environmentally favorable oil well acidizing treatments.

Características físicas e mecânicas de misturas de solo, cimento e casca de arroz Physical and mechanical characteristics of soil-cement and rice husk mixtures

Directory of Open Access Journals (Sweden)

Ana P. S. Milani

2006-04-01

Full Text Available Na presente pesquisa, estudaram-se os efeitos da adição da casca de arroz nas propriedades físico-mecânicas da mistura de solo-cimento, visando a obter composições de solo-cimento-casca de arroz com potencialidade para fabricação de materiais alternativos de construção. Foram realizados o fracionamento, o peneiramento e o pré-tratamento em solução de cal da casca de arroz. Foram determinadas as características físicas do solo e da casca de arroz, sendo executados ensaios de dosagem das misturas de solo-cimento-casca de arroz, aplicando-se às mesmas os ensaios de compactação normal de Proctor e o de compressão simples. Posteriormente, as composições de solo-cimento-casca de arroz foram submetidas aos ensaios de compressão simples e de tração na compressão diametral, aos 7 e aos 28 dias de idade, e de absorção d'água. Depois de determinadas as principais características físicas e mecânicas, pôde-se concluir que as misturas de solo + teor de 12% de combinações de cimento e casca de arroz se apresentaram como materiais promissores para a fabricação de elementos construtivos, a serem utilizados em construções e instalações rurais.The main objective of this work is the study of the effect of rice husk addition on the physical and mechanical properties of soil-cement, in order to obtain an alternative construction material. The rice husk preparation consisted of grinding, sieving, and the pre-treatment with lime solution. The physical characteristics of the soil and of the rice husk were determined. Different amounts of soil, cement and rice husk were tested by compaction and unconfined compression. The specimens molded according to the treatments applied to the mixtures were subsequently submitted to compression testing and to tensile splitting cylinder testing at 7 and 28 days of age and to water absorption testing. After determining its physical and mechanical characteristics, the best results were obtained

Characterization and chemical activity of Portland cement and two experimental cements with potential for use in dentistry.

Science.gov (United States)

Camilleri, J

2008-09-01

To evaluate the chemical activity of Portland cement and two other cement types with similar chemical composition to mineral trioxide aggregate with the aim of developing these cements for further applications in dentistry. The chemical composition of the three cement types namely Portland cement, calcium sulpho-aluminate cement and calcium fluoro-aluminate cement was evaluated by elemental analysis using energy dispersive analysis with X-ray under the scanning electron microscope and by X-ray diffraction analysis (XRD) to determine the phases. The constituents of the hydration reaction by-products were evaluated by XRD analysis of the set cements at 1, 7, 28 and 56 days and by analysis of the leachate by ion chromatography. The pH of both cements and leachate was determined at different time intervals. Cements admixed with micro-silica were also tested to determine the effect of micro-silica on the reaction by-products. All three cement types were composed of tricalcium silicate as the main constituent phase. The hydration reaction of Portland cement produced calcium hydroxide. However, this was not present in the other cements tested at all ages. Admixed micro-silica had little or no effect on the cements with regard to reaction by-products. The pH of all cements tested was alkaline. Both the experimental calcium sulpho-aluminate cement and calcium fluoro-aluminate cement had different hydration reactions to that of Portland cement even though calcium silicate was the major constituent element of both cement types. No calcium hydroxide was produced as a by-product to cement hydration. Micro-silica addition to the cement had no effect on the hydration reaction.

Design of Fit-for-Purpose Cement to Restore Cement-Caprock Seal Integrity

Science.gov (United States)

Provost, R.

2015-12-01

This project aims to study critical research needs in the area of rock-cement interfaces, with a special focus on crosscutting applications in the Wellbore Integrity Pillar of the SubTER initiative. This study will focus on design and test fit-for-purpose cement formulations. The goals of this project are as follows: 1) perform preliminary study of dispersing nanomaterial admixtures in Ordinary Portland Cement (OPC) mixes, 2) characterize the cement-rock interface, and 3) identify potential high-performance cement additives that can improve sorption behavior, chemical durability, bond strength, and interfacial fracture toughness, as appropriate to specific subsurface operational needs. The work presented here focuses on a study of cement-shale interfaces to better understand failure mechanisms, with particular attention to measuring bond strength at the cement-shale interface. Both experimental testing and computational modeling were conducted to determine the mechanical behavior at the interface representing the interaction of cement and shale of a typical wellbore environment. Cohesive zone elements are used in the finite element method to computationally simulate the interface of the cement and rock materials with varying properties. Understanding the bond strength and mechanical performance of the cement-formation interface is critical to wellbore applications such as sequestration, oil and gas production and exploration and nuclear waste disposal. Improved shear bond strength is an indication of the capability of the interface to ensure zonal isolation and prevent zonal communication, two crucial goals in preserving wellbore integrity. Understanding shear bond strength development and interface mechanics will provide an idea as to how the cement-formation interface can be altered under environmental changes (temperature, pressure, chemical degradation, etc.) so that the previously described objectives can be achieved. Sandia National Laboratories is a multi

[Effect of different bone cement dispersion types in the treatment of osteoporotic vertebral compression fracture].

Science.gov (United States)

Zhao, Yong-Sheng; Li, Qiang; Li, Qiang; Zheng, Yan-Ping

2017-05-25

To observe different bone cement dispersion types of PVP, PKP and manipulative reduction PVP and their effects in the treatment of senile osteoporotic vertebral compression fractures and the bone cement leakage rate. The clinical data of patients with osteoporotic vertebral compression fractures who underwent unilateral vertebroplasty from January 2012 to January 2015 was retrospectively analyzed. Of them, 56 cases including 22 males and 34 females aged from 60 to 78 years old were treated by PVP operation; Fouty-eight cases including 17 males and 31 females aged from 61 to 79 years old were treated by PKP operation; Forty-three cases including 15 males and 28 females aged from 60 to 76 years old were treated by manipulative reduction PVP operation. AP and lateral DR films were taken after the operation; the vertebral bone cement diffusion district area and mass district area were calculated with AutoCAD graphics processing software by AP and lateral DR picture, then ratio(K) of average diffusion area and mass area were calculated, defining K100% as diffusion type. Different bone cement dispersion types of PVP, PKP and manipulative reduction PVP operation were analyzed. According to bone cement dispersion types, patients were divided into diffusion type, mixed type and mass type groups.Visual analogue scale (VAS), vertebral body compression rate, JOA score and bone cement leakage rate were observed. All patients were followed up for 12-24 months with an average of 17.2 months. There was significant difference in bone cement dispersion type among three groups ( P <0.05). The constituent ratio of diffusion type, mixed type and mass type in PVP operation was 46.43%, 35.71%, 17.86%, in PKP was 16.67%, 37.50% , 45.83%, and in manipulative reduction PVP was 37.21%, 44.19% and 18.60%, respectively. PVP operation and manipulative reduction PVP were mainly composed of diffusion type and mixed type, while PKP was mainly composed of mass type and mixed type. There was no

Durability of Cement Composites Reinforced with Sisal Fiber

Science.gov (United States)

Wei, Jianqiang

understanding of degradation mechanisms, two approaches are proposed to mitigate the degradation of sisal fiber in the cement matrix. In order to relieve the aggressive environment of hydrated cement, cement substitution by a combination of metakaolin and nanoclay, and a combination of rice husk ash and limestone are studied. Both metakaolin and nanoclay significantly optimize the cement hydration, while the combination of these two supplementary cementitious materials validates their complementary and synergistic effect at different stages of aging. The presented approaches effectively reduce the calcium hydroxide content and the alkalinity of the pore solution, thereby mitigating the fiber degradation and improving both the initial mechanical properties and durability of the fiber-cement composites. The role of rice husk ash in cement modification is mainly as the active cementitious supplementary material. In order to improve the degradation resistance of sisal fiber itself, two novel, simple, and economical pretreatments of the fibers (thermal and sodium carbonate treatment) are investigated. Both thermal treatment and Na 2CO3 treatment effectively improve the durability of sisal fiber-reinforced concrete. The thermal treatment achieves improvement of cellulose's crystallization, which ensures the initial strength and improved durability of sisal fiber. A layer consisting of calcium carbonate sediments, which protects the internals of a fiber from the strong alkali pore solution, is formed and filled in pits and cavities on the Na2CO3 treated sisal fiber's surface.

Effects of cement particle size distribution on performance properties of Portland cement-based materials

Energy Technology Data Exchange (ETDEWEB)

Bentz, D.P.; Garboczi, E.J.; Haecker, C.J.; Jensen, O.M.

1999-10-01

The original size, spatial distribution, and composition of Portland cement particles have a large influence on hydration kinetics, microstructure development, and ultimate properties of cement-based materials. In this paper, the effects of cement particle size distribution on a variety of performance properties are explored via computer simulation and a few experimental studies. Properties examined include setting time, heat release, capillary porosity percolation, diffusivity, chemical shrinkage, autogenous shrinkage, internal relative humidity evolution, and interfacial transition zone microstructure. The effects of flocculation and dispersion of the cement particles in the starting microstructures on resultant properties are also briefly evaluated. The computer simulations are conducted using two cement particle size distributions that bound those commonly in use today and three different water-to-cement ratios: 0.5, 0.3, and 0.246. For lower water-to-cement ratio systems, the use of coarser cements may offer equivalent or superior performance, as well as reducing production costs for the manufacturer.

Low pH Cements

International Nuclear Information System (INIS)

Savage, David; Benbow, Steven

2007-05-01

The development of low-pH cements for use in geological repositories for radioactive waste stems from concerns over the potential for deleterious effects upon the host rock and other EBS materials (notably bentonite) under the hyperalkaline conditions (pH > 12) of cement pore fluids. Low pH cement (also known as low heat cement) was developed by the cement industry for use where large masses of cement (e.g. dams) could cause problems regarding heat generated during curing. In low pH cements, the amount of cement is reduced by substitution of materials such as fly ash, blast furnace slag, silica fume, and/or non-pozzolanic silica flour. SKB and Posiva have ruled out the use of blast furnace slag and fly-ash and are focusing on silica fume as a blending agent. Currently, no preferred composition has been identified by these agencies. SKB and Posiva have defined a pH limit ≤ 11 for cement grout leachates. To attain this pH, blending agents must comprise at least 50 wt % of dry materials. Because low pH cement has little, or no free portlandite, the cement consists predominantly of calcium silicate hydrate (CSH) gel with a Ca/Si ratio ≤ 0.8. Although there are potential implications for the performance of the spent fuel and cladding due to the presence of hyperalkaline fluids from cement, the principal focus for safety assessment lies with the behaviour of bentonite. There are a number of potential constraints on the interaction of hyperalkaline cement pore fluids with bentonite, including mass balance, thermodynamic issues, mass transport, and kinetics, but none of these is likely to be limiting if conventional OPC cements are employed in repository construction. Nevertheless: Low-pH cements may supply approximately 50 % less hydroxyl ions than conventional OPC for a given volume of cement, but mass balance constraints are complicated by the uncertainty concerning the type of secondary minerals produced during cement-bentonite interaction. The change of aqueous

Low pH Cements

Energy Technology Data Exchange (ETDEWEB)

Savage, David; Benbow, Steven [Quintessa Ltd., Henley-on-Thames (United Kingdom)

2007-05-15

The development of low-pH cements for use in geological repositories for radioactive waste stems from concerns over the potential for deleterious effects upon the host rock and other EBS materials (notably bentonite) under the hyperalkaline conditions (pH > 12) of cement pore fluids. Low pH cement (also known as low heat cement) was developed by the cement industry for use where large masses of cement (e.g. dams) could cause problems regarding heat generated during curing. In low pH cements, the amount of cement is reduced by substitution of materials such as fly ash, blast furnace slag, silica fume, and/or non-pozzolanic silica flour. SKB and Posiva have ruled out the use of blast furnace slag and fly-ash and are focusing on silica fume as a blending agent. Currently, no preferred composition has been identified by these agencies. SKB and Posiva have defined a pH limit {<=} 11 for cement grout leachates. To attain this pH, blending agents must comprise at least 50 wt % of dry materials. Because low pH cement has little, or no free portlandite, the cement consists predominantly of calcium silicate hydrate (CSH) gel with a Ca/Si ratio {<=} 0.8. Although there are potential implications for the performance of the spent fuel and cladding due to the presence of hyperalkaline fluids from cement, the principal focus for safety assessment lies with the behaviour of bentonite. There are a number of potential constraints on the interaction of hyperalkaline cement pore fluids with bentonite, including mass balance, thermodynamic issues, mass transport, and kinetics, but none of these is likely to be limiting if conventional OPC cements are employed in repository construction. Nevertheless: Low-pH cements may supply approximately 50 % less hydroxyl ions than conventional OPC for a given volume of cement, but mass balance constraints are complicated by the uncertainty concerning the type of secondary minerals produced during cement-bentonite interaction. The change of aqueous

Stainless and Galvanized Steel, Hydrophobic Admixture and Flexible Polymer-Cement Coating Compared in Increasing Durability of Reinforced Concrete Structures

Science.gov (United States)

Tittarelli, Francesca; Giosuè, Chiara; Mobili, Alessandra

2017-08-01

The use of stainless or galvanized steel reinforcements, a hydrophobic admixture or a flexible polymer-cement coating were compared as methods to improve the corrosion resistance of sound or cracked reinforced concrete specimens exposed to chloride rich solutions. The results show that in full immersion condition, negligible corrosion rates were detected in all cracked specimens, except those treated with the flexible polymer-cement mortar as preventive method against corrosion and the hydrophobic concrete specimens. High corrosion rates were measured in all cracked specimens exposed to wet-dry cycles, except for those reinforced with stainless steel, those treated with the flexible polymer-cement coating as restorative method against reinforcement corrosion and for hydrophobic concrete specimens reinforced with galvanized steel reinforcements.

Seating load parameters impact on dental ceramic reinforcement conferred by cementation with resin-cements.

LENUS (Irish Health Repository)

Addison, Owen

2010-09-01

Cementation of all-ceramic restorations with resin-cements has been demonstrated to reduce the incidence of fracture in service. The aim was to investigate the influence of loading force and loading duration applied during cementation on the reinforcement conferred by a resin-cement on a leucite reinforced glass-ceramic.

Mechanism of Hg(II) Immobilization in Sediments by Sulfate-Cement Amendment.

Science.gov (United States)

Serrano, Susana; Vlassopoulos, Dimitri; O'Day, Peggy A

2016-04-01

Reactive amendments such as Portland and super-sulfate cements offer a promising technology for immobilizing metalloid contaminants such as mercury (Hg) in soils and sediments through sequestration in less bioavailable solid forms. Tidal marsh sediments were reacted with dissolved Hg(II) in synthetic seawater and fresh water solutions, treated with Portland cement and FeSO 4 amendment, and aged for up to 90 days. Reacted solids were analyzed with bulk sequential extraction methods and characterized by powder X-ray diffraction (XRD), electron microscopy, and synchrotron X-ray absorption spectroscopy at the Hg L III - and S K-edge. In amended sediments, XRD, SEM and sulfur K-edge XANES indicated formation of gypsum in seawater experiments or ettringite-type (Ca 6 Al 2 (SO 4 ) 3 (OH) 12 . 26H 2 O) phases in fresh water experiments, depending on the final solution pH (seawater ∼8.5; freshwater ∼10.5). Analysis of Hg EXAFS spectra showed Cl and Hg ligands in the first- and second-coordination shells at distances characteristic of a polynuclear chloromercury(II) salt, perhaps as a nanoparticulate phase, in both seawater and fresh water experiments. In addition to the chloromercury species, a smaller fraction (∼20-25%) of Hg was bonded to O atoms in fresh water sample spectra, suggesting the presence of a minor sorbed Hg fraction. In the absence of amendment treatment, Hg sorption and resistance to extraction can be accounted for by relatively strong binding by reduced S species present in the marsh sediment detected by S XANES. Thermodynamic calculations predict stable aqueous Hg-Cl species at seawater final pH, but higher final pH in fresh water favors aqueous Hg-hydroxide species. The difference in Hg coordination between aqueous and solid phases suggests that the initial Hg-Cl coordination was stabilized in the cement hydration products and did not re-equilibrate with the bulk solution with aging. Collectively, results suggest physical encapsulation of Hg as a

Impact of watering with UV-LED-treated wastewater on microbial and physico-chemical parameters of soil.

Science.gov (United States)

Chevremont, A-C; Boudenne, J-L; Coulomb, B; Farnet, A-M

2013-04-15

Advanced oxidation processes based on UV radiations have been shown to be a promising wastewater disinfection technology. The UV-LED system involves innovative materials and could be an advantageous alternative to mercury-vapor lamps. The use of the UV-LED system results in good water quality meeting the legislative requirements relating to wastewater reuse for irrigation. The aim of this study was to investigate the impact of watering with UV-LED treated wastewaters (UV-LED WW) on soil parameters. Solid-state ¹³C NMR shows that watering with UV-LED WW do not change the chemical composition of soil organic matter compared to soil watered with potable water. Regarding microbiological parameters, laccase, cellulase, protease and urease activities increase in soils watered with UV-LED WW which means that organic matter brought by the effluent is actively degraded by soil microorganisms. The functional diversity of soil microorganisms is not affected by watering with UV-LED WW when it is altered by 4 and 8 months of watering with wastewater (WW). After 12 months, functional diversity is similar regardless of the water used for watering. The persistence of faecal indicator bacteria (coliform and enterococci) was also determined and watering with UV-LED WW does not increase their number nor their diversity unlike soils irrigated with activated sludge wastewater. The study of watering-soil microcosms with UV-LED WW indicates that this system seems to be a promising alternative to the UV-lamp-treated wastewaters. Copyright © 2013 Elsevier Ltd. All rights reserved.

C and N accumulations in soil aggregates determine nitrous oxide emissions from cover crop treated rice paddy soils during fallow season

International Nuclear Information System (INIS)

Pramanik, Prabhat; Haque, Md. Mozammel; Kim, Sang Yoon; Kim, Pil Joo

2014-01-01

Combination of leguminous and non-leguminous plant residues are preferably applied in rice paddy soils to increase the rate of organic matter mineralization and to improve plant growth. However, organic matter addition facilitates methane (CH 4 ) emission from rice paddy soil. Mineralization of organic nitrogen (N) increases NO 3 –N concentrations in soil, which are precursors for the formation of nitrous oxide (N 2 O). However, N 2 O is a minor greenhouse gas emitted from submerged rice field and hence is not often considered during calculation of total global warming potential (GWP) during rice cultivation. The hypothesis of this study was that fluxes of N 2 O emissions might be changed after removal of flooded water from rice field and the effect of cover crops on N 2 O emissions in the fallow season might be interesting. However, the effects of N-rich plant residues on N 2 O emission rates in the fallow season and its effect on annual GWP were not studied before. In this experiment, combination of barley (non-leguminous) and hairy vetch (leguminous) biomasses were applied at 9 Mg ha −1 and 27 Mg ha −1 rates in rice paddy soil. Cover crop application significantly increased CH 4 emission flux while decreased N 2 O emissions during rice cultivation. The lowest N 2 O emission was observed in 27 Mg ha −1 cover crop treated plots. Cover crop applications increased N contents in soil aggregates especially in smaller aggregates (< 250 μm), and that proportionately increased the N 2 O emission potentials of these soil aggregates. Fluxes of N 2 O emissions in the fallow season were influenced by the N 2 O emission potentials of soil aggregates and followed opposite trends as those observed during rice cultivation. Therefore, it could be concluded that the doses of cover crop applications for rice cultivation should not be optimized considering only CH 4 , but N 2 O should also be considered especially for fallow season to calculate total GWP. - Highlights: �

Longevity of metal-ceramic crowns cemented with self-adhesive resin cement: a prospective clinical study

Science.gov (United States)

Brondani, Lucas Pradebon; Pereira-Cenci, Tatiana; Wandsher, Vinicius Felipe; Pereira, Gabriel Kalil; Valandro, Luis Felipe; Bergoli, César Dalmolin

2017-04-10