The density of cement phases

International Nuclear Information System (INIS)

Balonis, M.; Glasser, F.P.

2009-01-01

The densities of principal crystalline phases occurring in Portland cement are critically assessed and tabulated, in some cases with addition of new data. A reliable and self-consistent density set for crystalline phases was obtained by calculating densities from crystallographic data and unit cell contents. Independent laboratory work was undertaken to synthesize major AFm and AFt cement phases, determine their unit cell parameters and compare the results with those recorded in the literature. Parameters were refined from powder diffraction patterns using CELREF 2 software. A density value is presented for each phase, showing literature sources, in some cases describing limitations on the data, and the weighting attached to numerical values where an averaging process was used for accepted data. A brief discussion is made of the consequences of the packing of water to density changes in AFm and AFt structures.

Physico-mechanical Properties of Electron Beam Irradiated Particle boards Based on Wood flour/ Polyethylene/Cement Kiln Dust Impregnated with Unsaturated Polyester

International Nuclear Information System (INIS)

Abdel-Rahman, H.A.; Khattab, M.M.; Ismail, M.R.

2010-01-01

Particle boards were fabricated by mixing wood flour (WF), low density polyethylene (LDPE) and cement kiln dust (CKD) under hot pressure; and then impregnated in unsaturated polyester resin. These impregnated particle boards were subjected to various doses of electron beam irradiation up to 50 kGy. The physico-mechanical properties were characterized in terms of flexural strength, impact strength, water absorption, thickness swelling, and the thermal stability. The results showed that the partial replacement of wood flour with cement kiln dust up to 20% by weight improved the values of flexural strength, and impact strength. However, the water absorption percentage and thickness swelling values decreased with increasing the CKD ratio up to 40%. Furthermore, the treatment with electron beam irradiation doses improved the physico-mechanical properties of the impregnated particle boards up to 50 kGy. The improved results were confirmed by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA)

Influence of different degrees of acetylation in the physical and mechanical properties of particleboards and wood-cement composites

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Setsuo Iwakiri

2014-12-01

Full Text Available Chemical modified wood particles used to particleboards manufacture may, at the same time, improve the dimensional stability and damage the internal bond. The aim of this research was find the optimal point of acetylation for particleboards. Pinus taeda particles with different degrees of acetylation, 8, 15 and 20% of weight percentage gain (WGP, were used in the production of particleboards with urea-formaldehyde resin and wood-cement composites produced by mechanical and vibratory compaction. It was evaluated the water absorption, thickness swelling and internal bind of the particleboards according to the European standards EN 317 and EN 319. Particleboards produced with 15 WPG showed the lowest water absorption and thickness swelling values. However, the use of chemically modified wood had a negative influence in the internal bind of the boards. This phenomenon can be explain due to the similar behavior between resin and water, that way, the high degree acetylation stops the adhesive and adherent bind. In the case of wood-cement composites, the internal bind improves as the acetylation degrees get higher. Nevertheless the inhibition of acetylated wood particles to the cement hydration got higher when the WPG was higher than 8%.

Sustainable Blended Cements-Influences of Packing Density on Cement Paste Chemical Efficiency.

Science.gov (United States)

Knop, Yaniv; Peled, Alva

2018-04-18

This paper addresses the development of blended cements with reduced clinker amount by partial replacement of the clinker with more environmentally-friendly material (e.g., limestone powders). This development can lead to more sustainable cements with reduced greenhouse gas emission and energy consumption during their production. The reduced clicker content was based on improved particle packing density and surface area of the cement powder by using three different limestone particle diameters: smaller (7 µm, 3 µm) or larger (70 µm, 53 µm) than the clinker particles, or having a similar size (23 µm). The effects of the different limestone particle sizes on the chemical reactivity of the blended cement were studied by X-ray diffraction (XRD), thermogravimetry and differential thermogravimetry (TG/DTG), loss on ignition (LOI), isothermal calorimetry, and the water demand for reaching normal consistency. It was found that by blending the original cement with limestone, the hydration process and the reactivity of the limestone itself were increased by the increased surface area of the limestone particles. However, the carbonation reaction was decreased with the increased packing density of the blended cement with limestone, having various sizes.

The incorporation of low and medium level radioactive wastes (solids and liquids) in cement

International Nuclear Information System (INIS)

Palmer, J.D.; Smith, D.L.G.

1986-01-01

The use of cement has been investigated for the immobilization of liquid and solid low and medium level radioactive waste. 220 litre mixing trials have demonstrated that the high temperatures generated during the setting of ordinary Portland cement/simulant waste mixes can be significantly reduced by the use of a blend of ground granulated blast furnace slag and ordinary Portland cement. Laboratory and 220 litre trials using simulant wastes showed that the blended cement gave an improvement in properties of the cemented waste product, e.g. stability and reduction in leach rates compared with ordinary Portland cement formulations. A range of 220 litre scale mixing systems for the incorporation of liquid and solid wastes in cement was investigated. The work has confirmed that cement-based processes can be used for the immobilization of most types of low and medium level waste

Specific Modulus and Density Profile as Characterization Criteria of Prefabricated Wood Composite Materials

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Pavel Král

2015-01-01

Full Text Available Wood based product industry has developed and modified a wide range of products to cater changing demands of construction industry. Development of a product necessitates characterization to ensure compliance to established standards. Traditionally a product was characterized by properties like bending properties, density and swelling factor etc. Whereas, advances in technology has introduced more sophisticated parameters which represent a combination of various classical factors and provide more practical and detailed information. In this study, we procured four different types of commercial products, viz. Gypsum board, cement board, oriented strand board and gypsum fiber board and tried to characterized them using density profile ratio and stiffness ratio. We observed some interesting empirical relations between various parameters as represented in various plots.

Temperature effects on wood anatomy, wood density, photosynthesis and biomass partitioning of Eucalyptus grandis seedlings.

Science.gov (United States)

Thomas, D S; Montagu, K D; Conroy, J P

2007-02-01

Wood density, a gross measure of wood mass relative to wood volume, is important in our understanding of stem volume growth, carbon sequestration and leaf water supply. Disproportionate changes in the ratio of wood mass to volume may occur at the level of the whole stem or the individual cell. In general, there is a positive relationship between temperature and wood density of eucalypts, although this relationship has broken down in recent years with wood density decreasing as global temperatures have risen. To determine the anatomical causes of the effects of temperature on wood density, Eucalyptus grandis W. Hill ex Maiden seedlings were grown in controlled-environment cabinets at constant temperatures from 10 to 35 degrees C. The 20% increase in wood density of E. grandis seedlings grown at the higher temperatures was variously related to a 40% reduction in lumen area of xylem vessels, a 10% reduction in the lumen area of fiber cells and a 10% increase in fiber cell wall thickness. The changes in cell wall characteristics could be considered analogous to changes in carbon supply. Lumen area of fiber cells declined because of reduced fiber cell expansion and increased fiber cell wall thickening. Fiber cell wall thickness was positively related to canopy CO2 assimilation rate (Ac), which increased 26-fold because of a 24-fold increase in leaf area and a doubling in leaf CO2 assimilation rate from minima at 10 and 35 degrees C to maxima at 25 and 30 degrees C. Increased Ac increased seedling volume, biomass and wood density; but increased wood density was also related to a shift in partitioning of seedling biomass from roots to stems as temperature increased.

Survival, growth, wood basic density and wood biomass of seven ...

African Journals Online (AJOL)

A performance comparison of seven-year-old individuals of 13 Casuarina species/provenances in terms of survival, growth (diameter, height and volume), wood basic density and wood biomass was undertaken at Kongowe, Kibaha, Tanzania. The trial was laid out using a randomised complete block design with four ...

Strength development in concrete with wood ash blended cement and use of soft computing models to predict strength parameters.

Science.gov (United States)

Chowdhury, S; Maniar, A; Suganya, O M

2015-11-01

In this study, Wood Ash (WA) prepared from the uncontrolled burning of the saw dust is evaluated for its suitability as partial cement replacement in conventional concrete. The saw dust has been acquired from a wood polishing unit. The physical, chemical and mineralogical characteristics of WA is presented and analyzed. The strength parameters (compressive strength, split tensile strength and flexural strength) of concrete with blended WA cement are evaluated and studied. Two different water-to-binder ratio (0.4 and 0.45) and five different replacement percentages of WA (5%, 10%, 15%, 18% and 20%) including control specimens for both water-to-cement ratio is considered. Results of compressive strength, split tensile strength and flexural strength showed that the strength properties of concrete mixture decreased marginally with increase in wood ash contents, but strength increased with later age. The XRD test results and chemical analysis of WA showed that it contains amorphous silica and thus can be used as cement replacing material. Through the analysis of results obtained in this study, it was concluded that WA could be blended with cement without adversely affecting the strength properties of concrete. Also using a new statistical theory of the Support Vector Machine (SVM), strength parameters were predicted by developing a suitable model and as a result, the application of soft computing in structural engineering has been successfully presented in this research paper.

CEMENT BONDED COMPOSITES – A MECHANICAL REVIEW

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Stephan Frybort

2008-05-01

Full Text Available Over the last years promising cement bonded wood composites for structural purposes have evolved. Durability, toughness, high dimen-sional stability, resistance against environmental influences such as biodegradation or weathering but also availability of the raw material as well as economic factors are features which can make cement-bonded composites superior to conventionally bonded composites. This paper reviews the relationship of diverse parameters, including density and particle size on mechanical and physical properties of cement bonded composites, based on published sources from the last 60 years. For general and recent information about bonding mechanisms, compatibility and setting problems, determination and improvement of compatibility, the used raw materials as well as accelerators are discussed. The main part deals with failure mechanisms in connection with several production parameters. Furthermore, the influence of particle size and geometry, orientation of the particles, cement-wood ratio and the effect of accelerators and treatment of the particles on modulus of elasticity, modulus of rupture as well as thickness swelling are discussed.

Effects of Different Wood Preservatives on The Some Physical Properties of Wood Species Used in Furniture and Building Industry

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Abdi Atılgan

2012-04-01

Full Text Available This study aims to determine the combustion, density values of Fagus and Pinus sylvestris’ woods impregranted with Ammonium tetra fluoro borate (1 - 3 % and the mixture of cement and borax (6 % – 9 % according to ASTM-D 1413-76 standards. In the combustion test carried out according to ASTM-D 160-50, the combustion resulted from flame, the self-combustion and the combustion as glowing processes were completed and the amount of lux, combustion duration, decomposition and ash were determined. According to experimental results, it is determined that Fogus’ wood has the highest retention (42,43 kg/m3 in the mixture of cement and borax 9 %, combustion tempature (587 o C in the mixture of cement and borax 6 % , the value of lux (267 lux in the the combustion as glowing and Pinus sylvestris’ wood has the longest combustion duration (29,03 min. Ammonium tetrafluoro borate 1%, the most weight loss (94 %.

Strength development in concrete with wood ash blended cement and use of soft computing models to predict strength parameters

Directory of Open Access Journals (Sweden)

S. Chowdhury

2015-11-01

Full Text Available In this study, Wood Ash (WA prepared from the uncontrolled burning of the saw dust is evaluated for its suitability as partial cement replacement in conventional concrete. The saw dust has been acquired from a wood polishing unit. The physical, chemical and mineralogical characteristics of WA is presented and analyzed. The strength parameters (compressive strength, split tensile strength and flexural strength of concrete with blended WA cement are evaluated and studied. Two different water-to-binder ratio (0.4 and 0.45 and five different replacement percentages of WA (5%, 10%, 15%, 18% and 20% including control specimens for both water-to-cement ratio is considered. Results of compressive strength, split tensile strength and flexural strength showed that the strength properties of concrete mixture decreased marginally with increase in wood ash contents, but strength increased with later age. The XRD test results and chemical analysis of WA showed that it contains amorphous silica and thus can be used as cement replacing material. Through the analysis of results obtained in this study, it was concluded that WA could be blended with cement without adversely affecting the strength properties of concrete. Also using a new statistical theory of the Support Vector Machine (SVM, strength parameters were predicted by developing a suitable model and as a result, the application of soft computing in structural engineering has been successfully presented in this research paper.

Compatibility of cement with low and medium level wastes generated at nuclear power plants

International Nuclear Information System (INIS)

De Angelis, G.

1987-01-01

The incorporation of low- and medium level wastes in cement can give rise to serious problems due to the interaction between radwastes and cement components. Some troubles can occur during the first stages of the cementation process while deleterious phenomena come into evidence in the medium and long term. With the aim to improve the quality of the final waste forms a pretreatment of the waste streams is often necessary, as well as the addition of special agents to the cement matrix. The prediction of the long-term behaviour of the final products is of main importance in this research field. To this purpose some accelerated tests have been proposed, but much effort should be further devoted to the comprehension of the waste/matrix interaction. In this paper the principal waste streams are reviewed together with the possible remedies which seem to be more suitable for their cementation. Thus the qpportunity of separatly handling and solidifying different types of waste is once more supported

Wood density variation in Gmelina arborea trees using X-ray densitometry

International Nuclear Information System (INIS)

Roque, Roger Moya; Tomazello, Mario

2005-01-01

The wood density constitutes the main wood quality parameter by its relationship with anatomical, physical and chemical properties and wood utilization. The modern and accurate methods - like X-ray densitometry - are applied to determine the density spatial distribution in wood sections and pith-bark direction. On the other hand, emphasis to wood utilization from fast growing plantations, like Gmelina arborea in Costa Rica, has been done. The objectives of this study were to determinate the influence of 2 climatic conditions of Costa Rica on radial wood density variation of gmelina trees form fast growing plantations using the X-ray densitometry method. Wood samples were cut at DBH of gmelina trees and transversal thin laths were selected at north-south direction and conditioned at 12% moisture content equilibrium and X-rayed. The radiographic films were revealed and scanned a 256 gray scale with 1000 dpi resolution and the intra tree-ring density were determined by CRAD and CERD software. The results demonstrated that the climatic and forest management affects the wood density variability and the distinctness of tree-ring boundaries of gmelina trees, as well as, the applicability of X-ray densitometry in wood quality analysis. (author)

Influence of bone density on the cement fixation of femoral hip resurfacing components.

Science.gov (United States)

Bitsch, Rudi G; Jäger, Sebastian; Lürssen, Marcus; Loidolt, Travis; Schmalzried, Thomas P; Clarius, Michael

2010-08-01

In clinical outcome studies, small component sizes, female gender, femoral shape, focal bone defects, bad bone quality, and biomechanics have been associated with failures of resurfacing arthroplasties. We used a well-established experimental setup and human bone specimens to analyze the effects of bone density on cement fixation of femoral hip resurfacing components. Thirty-one fresh frozen femora were prepared for resurfacing using the original instruments. ASR resurfacing prostheses were implanted after dual-energy X-ray densitometer scans. Real-time measurements of pressure and temperature during implantation, analyses of cement penetration, and measurements of micro motions under torque application were performed. The associations of bone density and measurement data were examined calculating regression lines and multiple correlation coefficients; acceptability was tested with ANOVA. We found significant relations between bone density and micro motion, cement penetration, cement mantle thickness, cement pressure, and interface temperature. Mean bone density of the femora was 0.82 +/- 0.13 g/cm(2), t-score was -0.7 +/- 1.0, and mean micro motion between bone and femoral resurfacing component was 17.5 +/- 9.1 microm/Nm. The regression line between bone density and micro motion was equal to -56.7 x bone density + 63.8, R = 0.815 (p density scans are most helpful for patient selection in hip resurfacing, and a better bone quality leads to higher initial component stability. A sophisticated cementing technique is recommended to avoid vigorous impaction and incomplete seating, since increasing bone density also results in higher cement pressures, lower cement penetration, lower interface temperatures, and thicker cement mantles. Copyright 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

A gauge for the measurement of wood density MGD-05

International Nuclear Information System (INIS)

Bartak, J.; Machaj, B.; Urbanski, P.; Pienkos, P.

2006-01-01

Wood density is an important parameter determining several properties of wood as: wood quality, mechanical resistance, charcoal production, transport cost, etc. Radiometric methods for the measurement of wood density are based on attenuation of 241 Am gamma radiation, or measurement of backscattered 241 Am radiation. In the paper authors describe the newly constructed computerized gauge designed for the non routine measurements. Up to 1000 measuring results can be stored in the gauge memory and the measuring results can be sent to an external laptop for computations of density contours

Simulating measures of wood density through the surface by Compton scattering

International Nuclear Information System (INIS)

Penna, Rodrigo; Oliveira, Arno H.; Braga, Mario R.M.S.S.; Vasconcelos, Danilo C.; Carneiro, Clemente J.G.; Penna, Ariane G.C.

2009-01-01

Monte Carlo code (MCNP-4C) was used to simulate a nuclear densimeter for measuring wood densities nondestructively. An Americium source (E = 60 keV) and a NaI (Tl) detector were placed on a wood block surface. Results from MCNP shown that scattered photon fluxes may be used to determining wood densities. Linear regressions between scattered photons fluxes and wood density were calculated and shown correlation coefficients near unity. (author)

The incorporation of low and medium level radioactive wastes (solids and liquids) in cement

International Nuclear Information System (INIS)

Palmer, J.D.; Smith, D.L.

1985-07-01

Experimentation has shown that high temperatures generated during the setting of ordinary Portland cement/simulant waste mixes can be significantly reduced by the use of a blend of ground granulated blast furnace slag and ordinary Portland cement. Trials on simulated waste showed that blended cement gave improved stability and a reduction in leach rates, and confirmed that the cement-based process can be used for the immobilisation of most types of low and medium level waste. (U.K.)

Medium-density fibreboard and occupational asthma. A case series.

Science.gov (United States)

Burton, C; Bradshaw, L; Agius, R; Burge, S; Huggins, V; Fishwick, D

2011-08-01

Medium-density fibreboard (MDF) is a wood composite material, composed primarily of softwood, bonded with a synthetic formaldehyde-based resin. It is increasingly used, as it has various advantages over natural woods. Enquiry of the national reporting scheme data and three case reports were used to further the evidence base linking this exposure to occupational asthma (OA). From 1991 to 2007, 21 cases of occupational sensitization to MDF were reported to the UK voluntary reporting scheme, Surveillance of Work Related Occupational Respiratory Disease (SWORD): 18 reported as occupational asthma (OA) and 3 as occupational rhinitis. All workers were male, with a mean age of 48 years, working in education, furniture manufacturing or joinery among other employments. Whilst reporting scheme data identified relatively small numbers of cases of OA likely to be due to MDF, the evidence base supporting this link is generally lacking. The three cases presented, where OA was attributed to MDF exposure, add to this evidence.

How the climate limits the wood density of angiosperms

Science.gov (United States)

Choi, Jin Woo; Kim, Ho-Young

2017-11-01

Flowering trees have various types of wood structure to perform multiple functions under their environmental conditions. In addition to transporting water from the roots to the canopy and providing mechanical support, the structure should provide resistance to embolism to maintain soil-plant-atmosphere continuum. By investigating existing data of the resistivity to embolism and wood density of 165 angiosperm species, here we show that the climate can limit the intrinsic properties of trees. Trees living in the dry environments require a high wood density to slow down the pressure decrease as it loses water relatively fast by evaporation. However, building too much tissues will result in the decrease of hydraulic conductivity and moisture concentration around mesophyll cells. To rationalize the biologically observed lower bound of the wood density, we construct a mechanical model to predict the wood density as a function of the vulnerability to embolism and the time for the recovery. Also, we build an artificial system using hydrogel microchannels that can test the probability of embolism as a function of conduit distributions. Our theoretical prediction is shown to be consistent with the results obtained from the artificial system and the biological data.

Corrosion resistance of cement brick on an organo-mineral base in a hydrogen sulfide medium

Energy Technology Data Exchange (ETDEWEB)

Potapov, A G; Belousov, G A; Pustovalov, V I; Skorikov, B M

1981-01-01

Results are presented of strength tests of cement brick made of different types of cement as a function of the composition of the mixing liquid and storage conditions. It is established that cement brick made of cement on a cinder base mixed in hydrogen sulfide water possesses the highest corrosive resistance to hydrogen sulfide attack. A marked increase in corrosion resistance is observed in cement brick on an organo-mineral base. Results of industrial tests of organo-mineral grouting mortar in a hydrogen sulfide medium are demonstrated.

Mechanical Properties and Decay Resistance of Hornbeam Cement Bonded Particleboards

Directory of Open Access Journals (Sweden)

Antonios N. Papadopoulos

2008-01-01

Full Text Available Cement bonded particleboards were manufactured from hornbeam (Carpinus betulus L. wood particles. Hydration tests were carried out to determine the inhibitory index in order to characterise wood-cement compatibility. The results revealed that the mixture of hornbeam-cement can be classified as moderate inhibition. Two wood: cement ratios were applied in this study, namely, 1 : 3 and 1 : 4, for the board manufacture. It was found that an increase of cement-wood ratio resulted in an improvement in all properties examined, except MOR. All properties of the boards made from 1 : 4 wood: cement ratio surpassed the minimum requirements set forth by the building type HZ code. Boards were exposed to brown and white rot fungi, Coniophora puteana, and Trametes versicolor, respectively. Overall, both fungi failed to attack the cement-bonded boards.

Calculation of crack stress density of cement base materials

Directory of Open Access Journals (Sweden)

Chun-e Sui

2018-01-01

Full Text Available In this paper, the fracture load of cement paste with different water cement ratio, different mineral admixtures, including fly ash, silica fume and slag, is obtained through experiments. the three-dimensional fracture surface is reconstructed and the three-dimensional effective area of the fracture surface is calculated. the effective fracture stress density of different cement paste is obtained. The results show that the polynomial function can accurately describe the relationship between the three-dimensional total area and the tensile strength

Use of wood as an alternative fuel to coal and natural gas at the Holnam Cement Plant, north of LaPorte, Colorado

Science.gov (United States)

Kurt H. Mackes

2001-01-01

The Holnam Company currently operates a cement plant north of Laporte, CO. The plant is attempting to use wood as an alternate fuel to coal and natural gas. The principal objective of this project is to investigate the extended use of wood as an alternate fuel at the plant. Tests conducted at Holnam indicate that wood is suitable for use at the plant and Holnam could...

Infrared thermography for wood density estimation

Science.gov (United States)

López, Gamaliel; Basterra, Luis-Alfonso; Acuña, Luis

2018-03-01

Infrared thermography (IRT) is becoming a commonly used technique to non-destructively inspect and evaluate wood structures. Based on the radiation emitted by all objects, this technique enables the remote visualization of the surface temperature without making contact using a thermographic device. The process of transforming radiant energy into temperature depends on many parameters, and interpreting the results is usually complicated. However, some works have analyzed the operation of IRT and expanded its applications, as found in the latest literature. This work analyzes the effect of density on the thermodynamic behavior of timber to be determined by IRT. The cooling of various wood samples has been registered, and a statistical procedure that enables one to quantitatively estimate the density of timber has been designed. This procedure represents a new method to physically characterize this material.

[Significance of bone mineral density and modern cementing technique for in vitro cement penetration in total shoulder arthroplasty].

Science.gov (United States)

Pape, G; Raiss, P; Kleinschmidt, K; Schuld, C; Mohr, G; Loew, M; Rickert, M

2010-12-01

Loosening of the glenoid component is one of the major causes of failure in total shoulder arthroplasty. Possible risk factors for loosening of cemented components include an eccentric loading, poor bone quality, inadequate cementing technique and insufficient cement penetration. The application of a modern cementing technique has become an established procedure in total hip arthroplasty. The goal of modern cementing techniques in general is to improve the cement-penetration into the cancellous bone. Modern cementing techniques include the cement vacuum-mixing technique, retrograde filling of the cement under pressurisation and the use of a pulsatile lavage system. The main purpose of this study was to analyse cement penetration into the glenoid bone by using modern cement techniques and to investigate the relationship between the bone mineral density (BMD) and the cement penetration. Furthermore we measured the temperature at the glenoid surface before and after jet-lavage of different patients during total shoulder arthroplasty. It is known that the surrounding temperature of the bone has an effect on the polymerisation of the cement. Data from this experiment provide the temperature setting for the in-vitro study. The glenoid surface temperature was measured in 10 patients with a hand-held non-contact temperature measurement device. The bone mineral density was measured by DEXA. Eight paired cadaver scapulae were allocated (n = 16). Each pair comprised two scapulae from one donor (matched-pair design). Two different glenoid components were used, one with pegs and the other with a keel. The glenoids for the in-vitro study were prepared with the bone compaction technique by the same surgeon in all cases. Pulsatile lavage was used to clean the glenoid of blood and bone fragments. Low viscosity bone cement was applied retrogradely into the glenoid by using a syringe. A constant pressure was applied with a modified force sensor impactor. Micro-computed tomography

Wood density and anatomy of three Eucalyptus species: implications for hydraulic conductivity

International Nuclear Information System (INIS)

Barotto, A.J.; Monteoliva, S.; Gyenge, J.; Martínez-Meier, A.; Moreno, K.; Tesón, N.; Fernández, M.E.

2017-01-01

Aim of the study: To characterize wood anatomical traits of three Eucalyptus species that differ in wood density and ecological requirements, and to examine the relationships between some anatomical features, wood density, and theoretical xylem hydraulic conductivity (Ks). Area of study: We analyzed 86 trees from three sites of Argentina (Entre Ríos and Buenos Aires Provinces). Methods: The sampled trees were Eucalyptus globulus, E. grandis and E. viminalis ranging from 11 to 15 years old. One stem disc was cut from each tree to determine wood density and identify quantitative anatomical features of vessels and fibers. Vessel composition (S, size - to-number ratio, a measure of vessel size distribution) and lumen fraction (F, the total sapwood area available for water transport) were estimated. Results: E. grandis, the species with the highest growth rates, presented the highest theoretical Ks. This was associated with anatomical features such as a high density of wide vessels resulting in high F. On the other hand, E. viminalis, the species with the lowest growth rates and highest resistance to environmental stress, showed lower Ks as a result of a low density of wide vessels. These two species differed not only greatly in wood density but also in fiber characteristics. In the case of E. globulus, vessels were relatively narrow, which resulted in the lowest theoretical Ks, fibers were small, and wood density intermediate. Research highlights: F had greater influence on Ks than S. The anatomical characteristics and wood density could only partly explain the differential growth or resistance to stress of the studied species.

Wood density and anatomy of three Eucalyptus species: implications for hydraulic conductivity

Directory of Open Access Journals (Sweden)

Antonio J. Barotto

2017-05-01

Full Text Available Aim of the study: To characterize wood anatomical traits of three Eucalyptus species that differ in wood density and ecological requirements, and to examine the relationships between some anatomical features, wood density, and theoretical xylem hydraulic conductivity (Ks. Area of study: We analyzed 86 trees from three sites of Argentina (Entre Ríos and Buenos Aires Provinces. Methods: The sampled trees were Eucalyptus globulus, E. grandis and E. viminalis ranging from 11 to 15 years old. One stem disc was cut from each tree to determine wood density and identify quantitative anatomical features of vessels and fibers. Vessel composition (S, size - to-number ratio, a measure of vessel size distribution and lumen fraction (F, the total sapwood area available for water transport were estimated. Results: E. grandis, the species with the highest growth rates, presented the highest theoretical Ks. This was associated with anatomical features such as a high density of wide vessels resulting in high F. On the other hand, E. viminalis, the species with the lowest growth rates and highest resistance to environmental stress, showed lower Ks as a result of a low density of wide vessels. These two species differed not only greatly in wood density but also in fiber characteristics. In the case of E. globulus, vessels were relatively narrow, which resulted in the lowest theoretical Ks, fibers were small, and wood density intermediate. Research highlights: F had greater influence on Ks than S. The anatomical characteristics and wood density could only partly explain the differential growth or resistance to stress of the studied species.

Wood density and anatomy of three Eucalyptus species: implications for hydraulic conductivity

Energy Technology Data Exchange (ETDEWEB)

Barotto, A.J.; Monteoliva, S.; Gyenge, J.; Martínez-Meier, A.; Moreno, K.; Tesón, N.; Fernández, M.E.

2017-11-01

Aim of the study: To characterize wood anatomical traits of three Eucalyptus species that differ in wood density and ecological requirements, and to examine the relationships between some anatomical features, wood density, and theoretical xylem hydraulic conductivity (Ks). Area of study: We analyzed 86 trees from three sites of Argentina (Entre Ríos and Buenos Aires Provinces). Methods: The sampled trees were Eucalyptus globulus, E. grandis and E. viminalis ranging from 11 to 15 years old. One stem disc was cut from each tree to determine wood density and identify quantitative anatomical features of vessels and fibers. Vessel composition (S, size - to-number ratio, a measure of vessel size distribution) and lumen fraction (F, the total sapwood area available for water transport) were estimated. Results: E. grandis, the species with the highest growth rates, presented the highest theoretical Ks. This was associated with anatomical features such as a high density of wide vessels resulting in high F. On the other hand, E. viminalis, the species with the lowest growth rates and highest resistance to environmental stress, showed lower Ks as a result of a low density of wide vessels. These two species differed not only greatly in wood density but also in fiber characteristics. In the case of E. globulus, vessels were relatively narrow, which resulted in the lowest theoretical Ks, fibers were small, and wood density intermediate. Research highlights: F had greater influence on Ks than S. The anatomical characteristics and wood density could only partly explain the differential growth or resistance to stress of the studied species.

Wood density variation and tree ring distinctness in Gmelina arborea trees by x-ray densitometry

Directory of Open Access Journals (Sweden)

Roger Moya

2009-03-01

Full Text Available Due to its relationship with other properties, wood density is the main wood quality parameter. Modern, accuratemethods such as X-ray densitometry - are applied to determine the spatial distribution of density in wood sections and to evaluatewood quality. The objectives of this study were to determinate the influence of growing conditions on wood density variation andtree ring demarcation of gmelina trees from fast growing plantations in Costa Rica. The wood density was determined by X-raydensitometry method. Wood samples were cut from gmelina trees and were exposed to low X-rays. The radiographic films weredeveloped and scanned using a 256 gray scale with 1000 dpi resolution and the wood density was determined by CRAD and CERDsoftware. The results showed tree-ring boundaries were distinctly delimited in trees growing in site with rainfall lower than 2510 mm/year. It was demonstrated that tree age, climatic conditions and management of plantation affects wood density and its variability. Thespecific effect of variables on wood density was quantified by for multiple regression method. It was determined that tree yearexplained 25.8% of the total variation of density and 19.9% were caused by climatic condition where the tree growing. Wood densitywas less affected by the intensity of forest management with 5.9% of total variation.

Functional relationships between wood structure and vulnerability to xylem cavitation in races of Eucalyptus globulus differing in wood density.

Science.gov (United States)

Barotto, Antonio José; Monteoliva, Silvia; Gyenge, Javier; Martinez-Meier, Alejandro; Fernandez, María Elena

2018-02-01

Wood density can be considered as a measure of the internal wood structure, and it is usually used as a proxy measure of other mechanical and functional traits. Eucalyptus is one of the most important commercial forestry genera worldwide, but the relationship between wood density and vulnerability to cavitation in this genus has been little studied. The analysis is hampered by, among other things, its anatomical complexity, so it becomes necessary to address more complex techniques and analyses to elucidate the way in which the different anatomical elements are functionally integrated. In this study, vulnerability to cavitation in two races of Eucalyptus globulus Labill. with different wood density was evaluated through Path analysis, a multivariate method that allows evaluation of descriptive models of causal relationship between variables. A model relating anatomical variables with wood properties and functional parameters was proposed and tested. We found significant differences in wood basic density and vulnerability to cavitation between races. The main exogenous variables predicting vulnerability to cavitation were vessel hydraulic diameter and fibre wall fraction. Fibre wall fraction showed a direct impact on wood basic density and the slope of vulnerability curve, and an indirect and negative effect over the pressure imposing 50% of conductivity loss (P50) through them. Hydraulic diameter showed a direct negative effect on P50, but an indirect and positive influence over this variable through wood density on one hand, and through maximum hydraulic conductivity (ks max) and slope on the other. Our results highlight the complexity of the relationship between xylem efficiency and safety in species with solitary vessels such as Eucalyptus spp., with no evident compromise at the intraspecific level. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Broad Anatomical Variation within a Narrow Wood Density Range—A Study of Twig Wood across 69 Australian Angiosperms

Science.gov (United States)

Ziemińska, Kasia; Westoby, Mark; Wright, Ian J.

2015-01-01

Objectives Just as people with the same weight can have different body builds, woods with the same wood density can have different anatomies. Here, our aim was to assess the magnitude of anatomical variation within a restricted range of wood density and explore its potential ecological implications. Methods Twig wood of 69 angiosperm tree and shrub species was analyzed. Species were selected so that wood density varied within a relatively narrow range (0.38–0.62 g cm-3). Anatomical traits quantified included wood tissue fractions (fibres, axial parenchyma, ray parenchyma, vessels, and conduits with maximum lumen diameter below 15 μm), vessel properties, and pith area. To search for potential ecological correlates of anatomical variation the species were sampled across rainfall and temperature contrasts, and several other ecologically-relevant traits were measured (plant height, leaf area to sapwood area ratio, and modulus of elasticity). Results Despite the limited range in wood density, substantial anatomical variation was observed. Total parenchyma fraction varied from 0.12 to 0.66 and fibre fraction from 0.20 to 0.74, and these two traits were strongly inversely correlated (r = -0.86, P area to sapwood area ratio, and modulus of elasticity (0.24 ≤|r|≤ 0.41, P area to sapwood area ratio (0.47 ≤|r|≤ 0.65, all P area spectrum. The fibre-parenchyma spectrum does not yet have any clear or convincing ecological interpretation. PMID:25906320

Broad Anatomical Variation within a Narrow Wood Density Range--A Study of Twig Wood across 69 Australian Angiosperms.

Science.gov (United States)

Ziemińska, Kasia; Westoby, Mark; Wright, Ian J

2015-01-01

Just as people with the same weight can have different body builds, woods with the same wood density can have different anatomies. Here, our aim was to assess the magnitude of anatomical variation within a restricted range of wood density and explore its potential ecological implications. Twig wood of 69 angiosperm tree and shrub species was analyzed. Species were selected so that wood density varied within a relatively narrow range (0.38-0.62 g cm-3). Anatomical traits quantified included wood tissue fractions (fibres, axial parenchyma, ray parenchyma, vessels, and conduits with maximum lumen diameter below 15 μm), vessel properties, and pith area. To search for potential ecological correlates of anatomical variation the species were sampled across rainfall and temperature contrasts, and several other ecologically-relevant traits were measured (plant height, leaf area to sapwood area ratio, and modulus of elasticity). Despite the limited range in wood density, substantial anatomical variation was observed. Total parenchyma fraction varied from 0.12 to 0.66 and fibre fraction from 0.20 to 0.74, and these two traits were strongly inversely correlated (r = -0.86, P area to sapwood area ratio, and modulus of elasticity (0.24 ≤|r|≤ 0.41, P area to sapwood area ratio (0.47 ≤|r|≤ 0.65, all P area spectrum. The fibre-parenchyma spectrum does not yet have any clear or convincing ecological interpretation.

Casting granular ion exchange resins with medium-active waste in cement

International Nuclear Information System (INIS)

Beijer, O.

1980-01-01

Medium active waste from nuclear power stations in Sweden is trapped in granular ion exchange resins. The resin is mixed with cement paste and cast in a concrete shell which is cubic and has an edge dimension of 1.2 m. In some cases the ion exchange cement mortar has cracked. The report presents laboratory sutdies of the properties of the ion exchange resin and the mortar. Also the leaching of the moulds has been investigated. It was shown that a mixture with a water cement ratio higher than about 0.5 swells considerably during the first weeks after casting. The diffusion constant for cesium 137 has been determined at 3.10 -4 cm 2 /24-hour period in conjunction with exposure of the mould and mortar to sea water. The Swedish language report has 400 pages with 90 figures and 30 tables. (author)

Wood density explains architectural differentiation across 145 co-occurring tropical tree species

NARCIS (Netherlands)

Iida, Y.; Poorter, L.; Sterck, F.J.; Kubo, T.; Kassim, A.R.; Potts, M.D.; Kohyama, T.S.

2012-01-01

1. Because of its mechanical properties, wood density may affect the way that trees expand their stem and crown to exploit favourable light conditions in a mechanically stable way. From engineering theory and wood density properties, it is predicted that in terms of biomass investment, low-density

Path analysis of the energy density of wood in eucalyptus clones.

Science.gov (United States)

Couto, A M; Teodoro, P E; Trugilho, P F

2017-03-16

Path analysis has been used for establishing selection criteria in genetic breeding programs for several crops. However, it has not been used in eucalyptus breeding programs yet. In the present study, we aimed to identify the wood technology traits that could be used as the criteria for direct and indirect selection of eucalyptus genotypes with high energy density of wood. Twenty-four eucalyptus clones were evaluated in a completely randomized design with five replications. The following traits were assessed: basic wood density, total extractives, lignin content, ash content, nitrogen content, carbon content, hydrogen content, sulfur content, oxygen content, higher calorific power, holocellulose, and energy density. After verifying the variability of all evaluated traits among the clones, a two-dimensional correlation network was used to determine the phenotypic patterns among them. The obtained coefficient of determination (0.94) presented a higher magnitude in relation to the effect of the residual variable, and it served as an excellent model for explaining the genetic effects related to the variations observed in the energy density of wood in all eucalyptus clones. However, for future studies, we recommend evaluating other traits, especially the morphological traits, because of the greater ease in their measurement. Selecting clones with high basic density is the most promising strategy for eucalyptus breeding programs that aim to increase the energy density of wood because of its high heritability and magnitude of the cause-and-effect relationship with this trait.

Broad Anatomical Variation within a Narrow Wood Density Range--A Study of Twig Wood across 69 Australian Angiosperms.

Directory of Open Access Journals (Sweden)

Kasia Ziemińska

Full Text Available Just as people with the same weight can have different body builds, woods with the same wood density can have different anatomies. Here, our aim was to assess the magnitude of anatomical variation within a restricted range of wood density and explore its potential ecological implications.Twig wood of 69 angiosperm tree and shrub species was analyzed. Species were selected so that wood density varied within a relatively narrow range (0.38-0.62 g cm-3. Anatomical traits quantified included wood tissue fractions (fibres, axial parenchyma, ray parenchyma, vessels, and conduits with maximum lumen diameter below 15 μm, vessel properties, and pith area. To search for potential ecological correlates of anatomical variation the species were sampled across rainfall and temperature contrasts, and several other ecologically-relevant traits were measured (plant height, leaf area to sapwood area ratio, and modulus of elasticity.Despite the limited range in wood density, substantial anatomical variation was observed. Total parenchyma fraction varied from 0.12 to 0.66 and fibre fraction from 0.20 to 0.74, and these two traits were strongly inversely correlated (r = -0.86, P < 0.001. Parenchyma was weakly (0.24 ≤|r|≤ 0.35, P < 0.05 or not associated with vessel properties nor with height, leaf area to sapwood area ratio, and modulus of elasticity (0.24 ≤|r|≤ 0.41, P < 0.05. However, vessel traits were fairly well correlated with height and leaf area to sapwood area ratio (0.47 ≤|r|≤ 0.65, all P < 0.001. Modulus of elasticity was mainly driven by fibre wall plus vessel wall fraction rather than by the parenchyma component.Overall, there seem to be at least three axes of variation in xylem, substantially independent of each other: a wood density spectrum, a fibre-parenchyma spectrum, and a vessel area spectrum. The fibre-parenchyma spectrum does not yet have any clear or convincing ecological interpretation.

The Effect of Water Cement Ratio on Cement Brick Containing High Density Polyethylene (HDPE as Sand Replacement

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Ali Noorwirdawati

2018-01-01

Full Text Available Waste disposal can contribute to the problem of environmental pollution. Most of the waste material is plastic based, because the nature of difficult of plastic degradable by itself. In order to overcome the problem, many study has been conducted on the reuse of plastic material into various field such as civil engineering and construction. In this study, municipal solid waste (MSW in the form of High Density Polyethylene (HDPE plastic was used to replace sand in cement sand brick production. The HDPE used in this study was obtained from a recycle factory at Nilai, Negeri Sembilan. 3% of HDPE replacement was applied in this study, with the cement-sand mix design of 1:6 and water-cement ratio 0.35, 0.40, 0.45 and 0.50 respectively. All specimens were tested for compressive strength and water absorption at 7 and 28 days. The density of the bricks was also recorded. The finding show that brick with 3% HDPE content and 0.45 of water-cement ratio at 28 days of age curing show the highest compressive strength, which is 19.5N/mm2 compared to the control specimen of 14.4 N/mm2.

High-resolution proxies for wood density variations in Terminalia superba

Science.gov (United States)

De Ridder, Maaike; Van den Bulcke, Jan; Vansteenkiste, Dries; Van Loo, Denis; Dierick, Manuel; Masschaele, Bert; De Witte, Yoni; Mannes, David; Lehmann, Eberhard; Beeckman, Hans; Van Hoorebeke, Luc; Van Acker, Joris

2011-01-01

Background and Aims Density is a crucial variable in forest and wood science and is evaluated by a multitude of methods. Direct gravimetric methods are mostly destructive and time-consuming. Therefore, faster and semi- to non-destructive indirect methods have been developed. Methods Profiles of wood density variations with a resolution of approx. 50 µm were derived from one-dimensional resistance drillings, two-dimensional neutron scans, and three-dimensional neutron and X-ray scans. All methods were applied on Terminalia superba Engl. & Diels, an African pioneer species which sometimes exhibits a brown heart (limba noir). Key Results The use of X-ray tomography combined with a reference material permitted direct estimates of wood density. These X-ray-derived densities overestimated gravimetrically determined densities non-significantly and showed high correlation (linear regression, R2 = 0·995). When comparing X-ray densities with the attenuation coefficients of neutron scans and the amplitude of drilling resistance, a significant linear relation was found with the neutron attenuation coefficient (R2 = 0·986) yet a weak relation with drilling resistance (R2 = 0·243). When density patterns are compared, all three methods are capable of revealing the same trends. Differences are mainly due to the orientation of tree rings and the different characteristics of the indirect methods. Conclusions High-resolution X-ray computed tomography is a promising technique for research on wood cores and will be explored further on other temperate and tropical species. Further study on limba noir is necessary to reveal the causes of density variations and to determine how resistance drillings can be further refined. PMID:21131386

Influence of Cellulosic Fibres on the Physical Properties of Fibre Cement Composites

Science.gov (United States)

Hospodarova, V.; Stevulova, N.; Vaclavik, V.; Dvorsky, T.

2017-10-01

Nowadays, there are new approaches directing to processing of non-conventional fibre-cement composites for application in the housing construction. Vegetable cellulosic fibres coming from natural resources used as reinforcement in cost-effective and environmental friendly building products are in the spotlight. The applying of natural fibres in cement based composites is narrowly linked to the ecological building sector, where a choice of materials is based on components including recyclable, renewable raw materials and low-resource manufacture techniques. In this paper, two types of cellulosic fibres coming from wood pulp and recycled waste paper with 0.2%; 0.3% and 0.5% of fibre addition into cement mixtures were used. Differences in the physical characteristics (flowability, density, coefficient of thermal conductivity and water absorbability) of 28 days hardened fibre-cement composites are investigated. Addition of cellulosic fibres to cement mixture caused worsening the workability of fresh mixture as well as absorbability of hardened composites due to hydrophilic nature of biomaterial, whereas density and thermal conductivity of manufactured cement based fibre plaster are enhanced. The physical properties of cement plasters based on cellulosic fibres depend on structural, physical characteristics of cellulosic fibres, their nature and processing.

Wood density and anatomy of three Eucalyptus species: implications for hydraulic conductivity

OpenAIRE

Antonio J. Barotto; Silvia Monteoliva; Javier Gyenge; Alejandro Martínez-Meier; Karen Moreno; Natalia Tesón; María Elena Fernández

2017-01-01

Aim of the study: To characterize wood anatomical traits of three Eucalyptus species that differ in wood density and ecological requirements, and to examine the relationships between some anatomical features, wood density, and theoretical xylem hydraulic conductivity (Ks). Area of study: We analyzed 86 trees from three sites of Argentina (Entre Ríos and Buenos Aires Provinces). Methods: The sampled trees were Eucalyptus globulus, E. grandis and E. viminalis ranging from 11 to 15 years...

Mechanical properties of wood-based composite materials

Science.gov (United States)

Zhiyong Cai; Robert J. Ross

2010-01-01

The term composite is used to describe any wood material bonded together with adhesives. The current product mix ranges from fiberboard to laminated beams and components. In this chapter, wood-based composite materials are classified into the following categories: panel products (plywood, oriented strandboard (OSB), particleboard, fiberboard, medium-density fiberboard...

Wood density and anatomy of three Eucalyptus species: implications for hydraulic conductivity

OpenAIRE

Barotto, Antonio J.; Monteoliva, Silvia; Gyenge, Javier; Martínez-Meier, Alejandro; Moreno, Karen; Tesón, Natalia; Fernández, María Elena

2017-01-01

Aim of the study: To characterize wood anatomical traits of three Eucalyptus species that differ in wood density and ecological requirements, and to examine the relationships between some anatomical features, wood density, and theoretical xylem hydraulic conductivity (Ks).Area of study: We analyzed 86 trees from three sites of Argentina (Entre Ríos and Buenos Aires Provinces).Methods: The sampled trees were Eucalyptus globulus, E. grandis and E. viminalis ranging from 11 to 15 years old. One ...

Effect of energy density and delay time on the degree of conversion and Knoop microhardness of a dual resin cement.

Science.gov (United States)

Mainardi, Maria do Carmo A J; Giorgi, Maria Cecília C; Lima, Débora A N L; Marchi, Giselle M; Ambrosano, Gláucia M; Paulillo, Luiz A M S; Aguiar, Flávio H B

2015-02-01

In the present study, we evaluated the influence of the photo-curing delay time and energy density on the degree of conversion and the Knoop microhardness of a resin cement. Seventy-eight samples were assigned to 13 groups (n = 6), one of which received no light curing (control). The samples were made of a dual-cured resin cement (RelyX ARC) with the aid of a Teflon matrix, submitted to one of the following energy densities (J/cm²): 7, 14, 20, and 28. Delay times were immediate (0), 1 min, or 2 min. After 24 h, the degree of conversion and microhardness were measured at three segments: cervical, medium, and apical. Data were submitted to three-way anova and Tukey's and Dunnett's tests, the latest of which was used to compare the control to the experimental groups. No interaction was observed between delay time and energy density regarding the degree of conversion. The cervical segment showed the highest values, while the apical showed the lowest. Microhardness values concerning the cervical segment in all groups were statistically different from that obtained for the control. A high-irradiance light-curing unit allows for a reduced irradiation exposure time with a short delay time, aimed at tooth restorations using a dual-cured resin cement. © 2014 Wiley Publishing Asia Pty Ltd.

Age trends and within-site effects in wood density and radial growth in Quercus faginea mature trees

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Vicelina B. Sousa

2016-04-01

Full Text Available Aim of the study: This paper aims to valorize the wood of Quercus faginea Lam. for high quality end uses (e.g. furniture by studying growth and quality properties using mature trees. Age trends in tree-ring width and wood density are shown and the main factors responsible for variations in tree-ring width and wood density within and between trees are investigated. Area of study: The study site is in the center of Portugal within the natural species distribution area.Material and methods: Radial samples from ten mature trees were collected at 6 heights (from base to 9.7 m and prepared for X-ray microdensity.Main results: Wood density showed high values, ranging from 0.868 g/cm3 to 0.957 g/cm3. Wood density decreased from pith to bark and with stem height. Cambial age showed a linear relationship with wood density and most of the variation in wood is explained by age. Intra-ring and axial within-tree homogeneity was good.Research highlights: Mature trees of Q. faginea showed high wood density and a high potential for high quality end uses, comparable to other oaks. Wood density is influenced by cambial age and tree-ring width. Wood quality may be improved by tree growth rates adjustment e.g. through an adequate tree stand density (e.g. thinning operations. 

Age trends and within-site effects in wood density and radial growth in Quercus faginea mature trees

Energy Technology Data Exchange (ETDEWEB)

Sousa, V.B.; Louzada, J.L.; Pereira, H.

2016-07-01

Aim of study: This paper aims to valorize the wood of Quercus faginea Lam. for high quality end uses (e.g. furniture) by studying growth and quality properties using mature trees. Age trends in tree-ring width and wood density are shown and the main factors responsible for variations in tree-ring width and wood density within and between trees are investigated. Area of study: The study site is in the center of Portugal within the natural species distribution area. Material and methods: Radial samples from ten mature trees were collected at 6 heights (from base to 9.7 m) and prepared for X-ray microdensity. Main results: Wood density showed high values, ranging from 0.868 g/cm3 to 0.957 g/cm3. Wood density decreased from pith to bark and with stem height. Cambial age showed a linear relationship with wood density and most of the variation in wood is explained by age. Intra-ring and axial within-tree homogeneity was good. Research highlights: Mature trees of Q. faginea showed high wood density and a high potential for high quality end uses, comparable to other oaks. Wood density is influenced by cambial age and tree-ring width. Wood quality may be improved by tree growth rates adjustment e.g. through an adequate tree stand density (e.g. thinning operations). (Author)

Age trends and within-site effects in wood density and radial growth in Quercus faginea mature trees

International Nuclear Information System (INIS)

Sousa, V.B.; Louzada, J.L.; Pereira, H.

2016-01-01

Aim of study: This paper aims to valorize the wood of Quercus faginea Lam. for high quality end uses (e.g. furniture) by studying growth and quality properties using mature trees. Age trends in tree-ring width and wood density are shown and the main factors responsible for variations in tree-ring width and wood density within and between trees are investigated. Area of study: The study site is in the center of Portugal within the natural species distribution area. Material and methods: Radial samples from ten mature trees were collected at 6 heights (from base to 9.7 m) and prepared for X-ray microdensity. Main results: Wood density showed high values, ranging from 0.868 g/cm3 to 0.957 g/cm3. Wood density decreased from pith to bark and with stem height. Cambial age showed a linear relationship with wood density and most of the variation in wood is explained by age. Intra-ring and axial within-tree homogeneity was good. Research highlights: Mature trees of Q. faginea showed high wood density and a high potential for high quality end uses, comparable to other oaks. Wood density is influenced by cambial age and tree-ring width. Wood quality may be improved by tree growth rates adjustment e.g. through an adequate tree stand density (e.g. thinning operations). (Author)

Significance of wood extractives for wood bonding.

Science.gov (United States)

Roffael, Edmone

2016-02-01

Wood contains primary extractives, which are present in all woods, and secondary extractives, which are confined in certain wood species. Extractives in wood play a major role in wood-bonding processes, as they can contribute to or determine the bonding relevant properties of wood such as acidity and wettability. Therefore, extractives play an immanent role in bonding of wood chips and wood fibres with common synthetic adhesives such as urea-formaldehyde-resins (UF-resins) and phenol-formaldehyde-resins (PF-resins). Extractives of high acidity accelerate the curing of acid curing UF-resins and decelerate bonding with alkaline hardening PF-resins. Water-soluble extractives like free sugars are detrimental for bonding of wood with cement. Polyphenolic extractives (tannins) can be used as a binder in the wood-based industry. Additionally, extractives in wood can react with formaldehyde and reduce the formaldehyde emission of wood-based panels. Moreover, some wood extractives are volatile organic compounds (VOC) and insofar also relevant to the emission of VOC from wood and wood-based panels.

Properties of concretes and wood composites using a phosphate-based binder

Science.gov (United States)

Hong, Luong Thanh

Magnesium potassium phosphate ceramics are from the family of phosphate-based cements which can be used as alternatives to Portland cements. In this study, concretes and wood composites were produced using magnesium potassium phosphate ceramic binders and supplementary materials including fly ash, sand, silica fume and sawdust. Bentonite, Delvo Stabilizer and baking soda were used as additives to increase the workability and the setting time of the fresh mixutres and decrease the density of the hardened products. The materials were then reinforced with chopped glass-fibers or textile glass-fabrics to increase their hardened properties. At 50% fly ash by total mass of the binder, the concretes had compressive strength and density of 33 MPa and 2170 kg/m3, respectively, after 90 days of simple curing. At 20% fly ash by total mass of the binder, the wood composites had compressive strength and density of 13 MPa and 1320 kg/m3, respectively, after 90 days. The flexural strengths were about 10% to 47% of the corresponding cylinder compressive strengths for these mixes. Increases in both compressive and flexural strengths for these mixes were observed with the addition of chopped glass-fibers or textile glass-fabrics.

BASIC DENSITY AND RETRACTIBILITY OF WOOD CLONES OF THREE Eucalyptus SPECIES

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Djeison Cesar Batista

2010-12-01

Full Text Available Among the planted forests that supply the national wood industry, the genus Eucalyptus has become the most important, due to its fast growth, ease of large scale planting and variability of wood use. The generation of new hybrids and clones is a reality in the national practice of silviculture, and there is great interest currently in finding genetic improvements, mainly for higher volumetric gains and resistance in rough conditions of planting, such as pest attacks, periods of drought, low soil fertility, etc. The basic density is one of the most important physical properties of wood because it relates directly to other properties, including the anisotropic shrinkage. Such properties indicate the rational use of a species in a certain wood product. The aim of this work was to determine the basic density and the anisotropic shrinkage of five wood clones for each one of the following species: Eucalyptus saligna, Eucalyptus grandis and Eucalyptus dunnii. Clone 5 of Eucalyptus saligna presented the highest basic density (0.56 g/cm³ and was the most dimensionally instable. Of all the species, there was only a direct relation among basic density, maximum volumetric shrinkage and maximum volumetric shrinkage coefficient in this clone. Considering maximum volumetric shrinkage as the criterion, clone 3 was the most dimensionally stable. Clones 2 and 3 of Eucalyptus grandis presented the least and the highest basic density, respectively, with 0.40 and 0.49 g/cm³. It was not possible to distinguish among clones 1, 3 and 4 in terms of dimensional stability, and considering maximum volumetric shrinkage coefficient as the criterion, clone 5 was the most dimensionally instable. For Eucalyptus saligna and Eucalyptus dunnii it was not possible to distinguish which clone presented the least basic density. Clone 3 of Eucalyptus dunnii presented the highest basic density (0.65 g/cm³ and considering maximum volumetric shrinkage coefficient as the criterion, it

Wood density variations of Norway spruce (Picea abies (L. Karst. under contrasting climate conditions in southwestern Germany

Directory of Open Access Journals (Sweden)

Marieke van der Maaten-Theunissen

2013-07-01

Full Text Available We analyzed inter-annual variations in ring width and maximum wood density of Norway spruce (Picea abies (L. Karst. at different altitudes in Baden-Württemberg, southwestern Germany, to determine the climate response of these parameters under contrasting climate conditions. In addition, we compared maximum, average and minimum wood density between sites. Bootstrapped correlation coefficients of ring width and maximum wood density with monthly temperature and precipitation, revealed a different climate sensitivity of both parameters. Ring width showed strong correlations with climate variables in the previous year and in the first half of the growing season. Further, a negative relationship with summer temperature was observed at the low-altitude sites. Maximum wood density correlated best with temperature during the growing season, whereby strongest correlations were found between September temperature and maximum wood density at the high-altitude sites. Observed differences in maximum, average and minimum wood density are suggested to relate to the local climate; with lower temperatures and higher water availability having a negative effect on wood density. 

Influence of particle packing density on the rheology of low cement content concrete

NARCIS (Netherlands)

Fennis-Huijben, S.A.A.M.; Grunewald, S.; Walraven, J.C.; Den Uijl, J.A.

2012-01-01

Optimizing concrete mixtures with regard to cement content is one of the most important solutions in sustainable concrete design. Workability o f these low cement content or ecological mixtures is very important. Eleven mortar mixtures are presented, which show how a higher packing density can be

Integration of vessel traits, wood density, and height in angiosperm shrubs and trees.

Science.gov (United States)

Martínez-Cabrera, Hugo I; Schenk, H Jochen; Cevallos-Ferriz, Sergio R S; Jones, Cynthia S

2011-05-01

Trees and shrubs tend to occupy different niches within and across ecosystems; therefore, traits related to their resource use and life history are expected to differ. Here we analyzed how growth form is related to variation in integration among vessel traits, wood density, and height. We also considered the ecological and evolutionary consequences of such differences. In a sample of 200 woody plant species (65 shrubs and 135 trees) from Argentina, Mexico, and the United States, standardized major axis (SMA) regression, correlation analyses, and ANOVA were used to determine whether relationships among traits differed between growth forms. The influence of phylogenetic relationships was examined with a phylogenetic ANOVA and phylogenetically independent contrasts (PICs). A principal component analysis was conducted to determine whether trees and shrubs occupy different portions of multivariate trait space. Wood density did not differ between shrubs and trees, but there were significant differences in vessel diameter, vessel density, theoretical conductivity, and as expected, height. In addition, relationships between vessel traits and wood density differed between growth forms. Trees showed coordination among vessel traits, wood density, and height, but in shrubs, wood density and vessel traits were independent. These results hold when phylogenetic relationships were considered. In the multivariate analyses, these differences translated as significantly different positions in multivariate trait space occupied by shrubs and trees. Differences in trait integration between growth forms suggest that evolution of growth form in some lineages might be associated with the degree of trait interrelation.

Investigation of Waste Paper Cellulosic Fibers Utilization into Cement Based Building Materials

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Viola Hospodarova

2018-03-01

Full Text Available Recently, the utilization of renewable natural cellulosic materials, such as wood, plants, and waste paper in the preparation of building materials has attracted significant interest. This is due to their advantageous properties, low environmental impact and low cost. The objective of this paper is to investigate the influence of recycled cellulosic fibers (in the amount 0.5 wt % of the filler and binder weight and superplasticizer (in the amount 0.5 wt % of the cement weight on the resulting properties of cement composites (consistency of fresh mixture, density, thermal conductivity, and compressive and flexural strength for hardening times of 1, 3, 7, 28, and 90 days. Plasticizer use improved the workability of fresh cement mixture. In comparison to the reference sample, the results revealed a decrease in density of 6.8% and in the thermal conductivity of composites with cellulosic fibers of 34%. The highest values of compressive (48.4 MPa and flexural (up to 7 MPa strength were achieved for hardened fiber cement specimens with plasticizer due to their significantly better dispersion of cement particles and improved bond strength between fibers and matrix.

Wood density variations of Norway spruce (Picea abies (L. Karst. under contrasting climate conditions in southwestern Germany

Directory of Open Access Journals (Sweden)

Marieke van der Maaten-Theunissen

2013-05-01

Full Text Available We analyzed inter-annual variations in ring width and maximumwood density of Norway spruce (Picea abies (L. Karst. at different altitudes in Baden-Württemberg, southwestern Germany, to determine the climate response of these parameters under contrasting climate conditions. In addition, we compared maximum, average and minimum wood density between sites. Bootstrapped correlation coefficients of ring width and maximum wood density with monthly temperature and precipitation, revealed a different climate sensitivity of both parameters. Ring width showed strong correlations with climate variables in the previous year and in the first half of the growingseason. Further, a negative relationship with summer temperature was observed at the low-altitude sites. Maximum wood density correlated best with temperature during the growing season, whereby strongest correlations were found between September temperature and maximum wood density at the high-altitude sites. Observed differences in maximum, average and minimum wood density are suggested to relate to the local climate; with lower temperature and higher water availability having a negative effect on wood density.

Variation of Ring Width and Wood Density in Two Unmanaged Stands of the Mediterranean Oak Quercus faginea

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Vicelina B. Sousa

2018-01-01

Full Text Available Ring width and wood density variation were studied from pith-to-bark and along the stem in two naturally regenerated stands of Quercus faginea Lam. in Portugal. Ring width was significantly different between sites, in both heartwood and sapwood rings, ranging from 1.83 mm to 2.52 mm and from 0.77 mm to 2.11 mm, respectively. Wood density was significantly different between sites only in the heartwood, i.e., 914 kg m−3 and 1037 kg m−3. Site effects were the main source of variation for ring width and wood density within the heartwood as well as for sapwood ring width, while the between-tree effects explained more the density variation within the sapwood. Wood density showed within-tree uniformity that was not affected by site. The stand characteristics such as basal area and tree age may override the environmental growth conditions. There was also a weak correlation between wood density and ring width components therefore suggesting the possibility of forestry management for both fast tree growth and high wood density.

Insights into intraspecific wood density variation and its relationship to growth, height and elevation in a treeline species.

Science.gov (United States)

Fajardo, A

2018-05-01

The wood economics spectrum provides a general framework for interspecific trait-trait coordination across wide environmental gradients. Whether global patterns are mirrored within species constitutes a poorly explored subject. In this study, I first determined whether wood density co-varies together with elevation, tree growth and height at the within-species level. Second, I determined the variation of wood density in different stem parts (trunk, branch and twigs). In situ trunk sapwood, trunk heartwood, branch and twig densities, in addition to stem growth rates and tree height were determined in adult trees of Nothofagus pumilio at four elevations in five locations spanning 18° of latitude. Mixed effects models were fitted to test relationships among variables. The variation in wood density reported in this study was narrow (ca. 0.4-0.6 g cm -3 ) relative to global density variation (ca. 0.3-1.0 g cm -3 ). There was no significant relationship between stem growth rates and wood density. Furthermore, the elevation gradient did not alter the wood density of any stem part. Trunk sapwood density was negatively related to tree height. Twig density was higher than branch and trunk densities. Trunk heartwood density was always significantly higher than sapwood density. Negative across-species trends found in the growth-wood density relationship may not emerge as the aggregate of parallel intraspecific patterns. Actually, trees with contrasting growth rates show similar wood density values. Tree height, which is tightly related to elevation, showed a negative relationship with sapwood density. © 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

Experimental study of electric conductivity, density and viscosity of Wood's alloy

International Nuclear Information System (INIS)

Kazandzhan, B.I.; Matveev, V.M.; Savich, T.B.; Umarov, A.M.

1989-01-01

Electric conductivity, density and kinematic viscosity of commercially pure Wood's alloy are obtained in a wide temperature range. Electric conductivity and density are investigated from the room temperature to 1000 K. Measurements of kinematic viscosity are carried out from 372 to 1000 K by means of torsional vibrations method using informatiom computer system permitting to automate data acquisition and processing and to increase the measurement accuracy. On the basis of analysis the character of electric conductivity and kinematic viscosity polyterms Wood's alloy liquidus and solidus temperatures are estimated

A descriptive study of the radiographic density of implant restorative cements.

Science.gov (United States)

Wadhwani, Chandur; Hess, Timothy; Faber, Thomas; Piñeyro, Alfonso; Chen, Curtis S K

2010-05-01

Cementation of implant prostheses is a common practice. Excess cement in the gingival sulcus may harm the periodontal tissues. Identification of the excess cement may be possible with the use of radiographs if the cement has sufficient radiopacity. The purpose of this study was to compare the radiographic density of different cements used for implant prostheses. Eight different cements were compared: TempBond Original (TBO), TempBond NE (TBN), Fleck's (FL), Dycal (DY), RelyX Unicem (RXU), RelyX Luting (RXL), Improv (IM), and Premier Implant Cement (PIC). Specimen disks, 2 mm in thickness, were radiographed. Images were made using photostimulable phosphor (PSP) plates with standardized exposure values. The average grey level of the central area of each specimen disk was selected and measured in pixels using a software analysis program, ImageTool, providing an average grey level value representative of radiodensity for each of the 8 cements. The radiodensity was determined using the grey level values of the test materials, which were recorded and compared to a standard aluminum step wedge. An equivalent thickness of aluminum in millimeters was calculated using best straight line fit estimates. To assess contrast effects by varying the exposure settings, a second experiment using 1-mm-thick cement specimens radiographed at both 60 kVp and 70 kVp was conducted. The PSP plates with specimens were measured for a grey level value comparison to the standard aluminum step wedge, using the same software program. The highest grey level values were recorded for the zinc cements (TBO, TBN, and FL), with the 1-mm specimen detectable at both 60- and 70-kVp settings. A lower grey level was recorded for DY, indicative of a lower radiodensity compared to the zinc cements, but higher than RXL and RXU. The implant-specific cements had the lowest grey level values. IM could only be detected in 2-mm-thick sections with a lower aluminum equivalence value than the previously mentioned

EFFECTS OF EXTRACTIVES AND DENSITY ON NATURAL RESISTANCE OF WOODS TO TERMITE Nasutitermes corniger

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Juarez Benigno Paes

2015-12-01

Full Text Available The evaluation of the natural resistance of wood to wood-destroying organisms is of fundamental importance in the choice of species to be used in buildings and furniture industry. Thus, the effects of extractives and wood density on biological resistance of Acacia mangium, Casuarina equisetifolia, Corymbia torelliana, Eucalyptus cloeziana, Tectona grandis and Caesalpinia echinata woods to the xylophagous termite Nasutitermes corniger was evaluated under laboratory conditions. Test samples, with dimensions of 2.00 x 2.54 x 0.64 cm (radial x tangential x longitudinal in four positions in pith-bark direction (internal heart, intermediate heart, outer heart and sapwood were taken. The woods were exposed to termite action for 28 days in no-choice feeding test. The samples not selected for the termite test were turned into sawdust and the extractive contents were obtained using the shavings that passed through the sieve of 40 and were retained in the sieve of 60 mesh. The wood natural resistance, within the pith-bark positions, for the studied species, is not correlated with the density and extractive content. However, among the woods, those with higher density and extractive content are more resistant. The woods with greater biological resistance to the termite Nasutitermes corniger (smaller mass loss, waste and survival time of insects are Corymbia torelliana and Caesalpinia echinata and of less resistance is Casuarina equisetifolia.

Influence of power density and primer application on polymerization of dual-cured resin cements monitored by ultrasonic measurement.

Science.gov (United States)

Takubo, Chikako; Yasuda, Genta; Murayama, Ryosuke; Ogura, Yukari; Tonegawa, Motoka; Kurokawa, Hiroyasu; Miyazaki, Masashi

2010-08-01

We used ultrasonic measurements to monitor the influence of power density and primer application on the polymerization reaction of dual-cured resin cements. The ultrasonic equipment comprised a pulser-receiver, transducers, and an oscilloscope. Resin cements were mixed and inserted into a transparent mould, and specimens were placed on the sample stage, onto which the primer, if used, was also applied. Power densities of 0 (no irradiation), 200, or 600 mW cm(-2) were used for curing. The transit time through the cement disk was divided by the specimen thickness to obtain the longitudinal sound velocity. When resin cements were light-irradiated, each curve displayed an initial plateau of approximately 1,500 m s(-1), which rapidly increased to a second plateau of 2,300-2,900 m s(-1). The rate of sound velocity increase was retarded when the cements were light-irradiated at lower power densities, and increased when the primer was applied. The polymerization behaviour of dual-cured resin cements was therefore shown to be affected by the power density of the curing unit and the application of self-etching primer. (c) 2010 The Authors. Journal compilation (c) 2010 Eur J Oral Sci.

Modeling relaxation length and density of acacia mangium wood using gamma - ray attenuation technique

International Nuclear Information System (INIS)

Tamer A Tabet; Fauziah Abdul Aziz

2009-01-01

Wood density measurement is related to the several factors that influence wood quality. In this paper, density, relaxation length and half-thickness value of eight ages, 3, 5, 7, 10, 11, 13 and 15 year-old of Acacia mangium wood were determined using gamma radiation from 137 Cs source. Results show that Acacia mangium tree of age 3 year has the highest relaxation length of 83.33 cm and least density of 0.43 gcm -3 , while the tree of age 15 year has the least Relaxation length of 28.56 cm and highest density of 0.76 gcm -3 . Results also show that the 3 year-old Acacia mangium wood has the highest half thickness value of 57.75 cm and 15 year-old tree has the least half thickness value of 19.85 cm. Two mathematical models have been developed for the prediction of density, variation with relaxation length and half-thickness value of different age of tree. A good agreement (greater than 85% in most cases) was observed between the measured values and predicted ones. Very good linear correlation was found between measured density and the age of tree (R2 = 0.824), and between estimated density and Acacia mangium tree age (R2 = 0.952). (Author)

Effect of the medium's density on the hydrocyclonic separation of waste plastics with different densities.

Science.gov (United States)

Fu, Shuangcheng; Fang, Yong; Yuan, Huixin; Tan, Wanjiang; Dong, Yiwen

2017-09-01

Hydrocyclones can be applied to recycle waste plastics with different densities through separating plastics based on their differences in densities. In the process, the medium density is one of key parameters and the value of the medium's density is not just the average of the density of two kinds of plastics separated. Based on the force analysis and establishing the equation of motion of particles in the hydrocyclone, a formula to calculate the optimum separation medium density has been deduced. This value of the medium's density is a function of various parameters including the diameter, density, radial position and tangential velocity of particles, and viscosity of the medium. Tests on the separation performance of the hydrocyclone has been conducted with PET and PVC particles. The theoretical result appeared to be in good agreement with experimental results. Copyright © 2017 Elsevier Ltd. All rights reserved.

RELATIONSHIPS BETWEEN ANATOMICAL FEATURES AND INTRA-RING WOOD DENSITY PROFILES IN Gmelina arborea APPLYING X-RAY DENSITOMETRY

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Mario Tomazelo-Filho

2007-12-01

Full Text Available Four annual tree-rings (2 of juvenile wood and 2 of mature wood were sampled from fast-growth plantations ofGmelina arborea in two climatic conditions (dry and wet tropical in Costa Rica. Each annual tree-ring was divided in equal parts ina radial direction. For each part, X-ray density as well as vessel percentage, length and width fiber, cell wall thickness and lumendiameter were measured. Wood density and profile patterns of cell dimension demonstrated inconsistency between juvenile andmature wood and climatic conditions. The Pearson correlation matrix showed that intra-ring wood density was positively correlatedwith the cell wall thickness and negatively correlated with vessel percentage, fiber length, lumen diameter and width. The forwardstepwise regressions determined that: (i intra-ring wood density variation could be predicted from 76 to 96% for anatomicalvariation; (ii cell wall thickness was the most important anatomical feature to produce intra-ring wood density variation and (iii thevessel percentage, fiber length, lumen diameter and width were the second most statically significant characteristics to intra-ring wooddensity, however, with low participation of the determination coefficient of stepwise regressions.

USE OF CANDEIA’S (Eremanthus erythropappus WASTE WOOD

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Rosimeire Cavalcante dos Santos

2008-09-01

Full Text Available The candeia (Eremanthus erythropappus is a native forest species with multiple uses and specially utilized as essential oils source. The use of the candeia´s waste wood after oil extraction for particle panels production becomes a viable alternative, avoiding environmental problems and increasing the availability of these products in the consuming market. This work verified the viability of producing wood-cement panels using waste wood generated after the extraction of candeia’s oil, in association with pinus and eucalipto woods. The experiment was installed according to a completely randomized design with three repetitions. The treatments were arranged according to a factorial 2 x 3 scheme (two wooden species and three replacement percentages of the woods by candeia’s waste. The results of the physical and mechanical property tests showed high potentiality of candeia waste wood, after oil extraction, in association with pinus and eucalipto wood for manufacturing wood-cement panels.

Evaluation of the CDTN's cementation facility using the results obtained in two different sizes: laboratory and facility

International Nuclear Information System (INIS)

Haucz, Maria Judite A.; Calabria, Jaqueline A. Almeida; Tello, Cledola Cassia O.; Candido, Francisco Donizete; Seles, Sandro Rogerio Novaes

2011-01-01

At CDTN R and D activities generate low-level radioactive wastes, among them the aqueous liquid ones, which need special attention due to their volumes. The usual treatment for these wastes is the volume reduction process using chemicals in order to change the radionuclides of the waste to an insoluble form. The resultant sludge is incorporated into cement in 200-liter drums using an in-line batch mixing system (CDTN Cementation Facility). The process parameters and solidified product quality are evaluated at the Cementation Laboratory (LABCIM), where tests are carried out to determine the viscosity, set time and density of the paste. In addition of the visual examination, compressive strength test and density are also established in the solidified product. In the cementation facility some pastes are also prepared for the immobilization of non-compactable waste, such as dump, scrap metal, wood, and other ones. This paper aims to present the study comparing the results of tests done in the pastes and products prepared in LABCIM and the ones obtained in CDTN's cementation facility, in order to check the efficiency of the cementation system. (author)

Evaluation of the CDTN cementation facility using the results obtained in two different sizes: laboratory and facility

International Nuclear Information System (INIS)

Haucz, Maria Judite A.; Calabria, Jaqueline A. Almeida; Tello, Cledola Cassia O.; Candido, Francisco Donizete; Seles, Sandro Rogerio Novaes

2011-01-01

At CDTN R and D activities generate low-level radioactive wastes, among them the aqueous liquid ones, which need special attention due to their volumes. The usual treatment for these wastes is the volume reduction process using chemicals in order to change the radionuclides of the waste to an insoluble form. The resultant sludge is incorporated into cement in 200-liter drums using an in-line batch mixing system (CDTN Cementation Facility). The process parameters and solidified product quality are evaluated at the Cementation Laboratory (LABCIM), where tests are carried out to determine the viscosity, set time and density of the paste. In addition of the visual examination, compressive strength test and density are also established in the solidified product. In the cementation facility some pastes are also prepared for the immobilization of non-compactable waste, such as dump, scrap metal, wood, and other ones. This paper aims to present the study comparing the results of tests done in the pastes and products prepared in LABCIM and the ones obtained in CDTN's cementation facility, in order to check the efficiency of the cementation system. (author)

Radiocarbon dating and wood density chronologies of mangrove trees in arid Western Australia.

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Nadia S Santini

Full Text Available Mangrove trees tend to be larger and mangrove communities more diverse in tropical latitudes, particularly where there is high rainfall. Variation in the structure, growth and productivity of mangrove forests over climatic gradients suggests they are sensitive to variations in climate, but evidence of changes in the structure and growth of mangrove trees in response to climatic variation is scarce. Bomb-pulse radiocarbon dating provides accurate dates of recent wood formation and tree age of tropical and subtropical tree species. Here, we used radiocarbon techniques combined with X-ray densitometry to develop a wood density chronology for the mangrove Avicennia marina in the Exmouth Gulf, Western Australia (WA. We tested whether wood density chronologies of A. marina were sensitive to variation in the Pacific Decadal Oscillation Index, which reflects temperature fluctuations in the Pacific Ocean and is linked to the instrumental rainfall record in north WA. We also determined growth rates in mangrove trees from the Exmouth Gulf, WA. We found that seaward fringing A. marina trees (~10 cm diameter were 48 ± 1 to 89 ± 23 years old (mean ± 1 σ and that their growth rates ranged from 4.08 ± 2.36 to 5.30 ± 3.33 mm/yr (mean ± 1 σ. The wood density of our studied mangrove trees decreased with increases in the Pacific Decadal Oscillation Index. Future predicted drying of the region will likely lead to further reductions in wood density and their associated growth rates in mangrove forests in the region.

Wood fibre density measurement with 238 Pu radiation

International Nuclear Information System (INIS)

Barry, B.J.; Baker, D.B.

1996-01-01

The form of the curve of attenuation by wood fibre of the X radiation from 238 Pu has been determined. An exponential function containing a term second order in the areal density of the fibre described the curve accurately. The effect of scatter is negligible, even with an uncollimated radiation beam. (author). 18 refs., 1 tab., 6 figs

Life cycle assessment of medium-density fiberboard (MDF) manufacturing process in Brazil.

Science.gov (United States)

Piekarski, Cassiano Moro; de Francisco, Antonio Carlos; da Luz, Leila Mendes; Kovaleski, João Luiz; Silva, Diogo Aparecido Lopes

2017-01-01

Brazil is one of the largest producers of medium-density fibreboard (MDF) in the world, and also the MDF has the highest domestic consumption and production rate in the country. MDF applications are highlighted into residential and commercial furniture design and also a wide participation in the building sector. This study aimed to propose ways of improving the environmental cradle-to-gate life-cycle of one cubic meter MDF panel by means of a life-cycle assessment (LCA) study. Complying with requirements of ISO 14040 and 14,044 standards, different MDF manufacturing scenarios were modelled using Umberto® v.5.6 software and the Ecoinvent v.2.2 life-cycle inventory (LCI) database for the Brazilian context. Environmental and human health impacts were assessed by using the CML (2001) and USEtox (2008) methods. The evaluated impact categories were: acidification, global warming, ozone layer depletion, abiotic resource depletion, photochemical formation of tropospheric ozone, ecotoxicity, eutrophication and human toxicity. Results identified the following hotspots: gas consumption at the thermal plant, urea-formaldehyde resin, power consumption, wood chip consumption and wood chip transportation to the plant. The improvement scenario proposals comprised the following actions: eliminate natural gas consumption at the thermal plant, reduce electrical power consumption, reduce or replace urea-formaldehyde resin consumption, reduce wood consumption and minimize the distance to wood chip suppliers. The proposed actions were analysed to verify the influence of each action on the set of impact categories. Among the results, it can be noted that a joint action of the proposed improvements can result in a total reduction of up to 38.5% of impacts to OD, 34.4% to AD, 31.2% to ET, and 30.4% to HT. Finally, MDF was compared with particleboard production in Brazil, and additional opportunities to improve the MDF environmental profile were identified. Copyright © 2016 Elsevier B

A comparison of wood density between classical Cremonese and modern violins.

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Berend C Stoel

Full Text Available Classical violins created by Cremonese masters, such as Antonio Stradivari and Giuseppe Guarneri Del Gesu, have become the benchmark to which the sound of all violins are compared in terms of their abilities of expressiveness and projection. By general consensus, no luthier since that time has been able to replicate the sound quality of these classical instruments. The vibration and sound radiation characteristics of a violin are determined by an instrument's geometry and the material properties of the wood. New test methods allow the non-destructive examination of one of the key material properties, the wood density, at the growth ring level of detail. The densities of five classical and eight modern violins were compared, using computed tomography and specially developed image-processing software. No significant differences were found between the median densities of the modern and the antique violins, however the density difference between wood grains of early and late growth was significantly smaller in the classical Cremonese violins compared with modern violins, in both the top (Spruce and back (Maple plates (p = 0.028 and 0.008, respectively. The mean density differential (SE of the top plates of the modern and classical violins was 274 (26.6 and 183 (11.7 gram/liter. For the back plates, the values were 128 (2.6 and 115 (2.0 gram/liter. These differences in density differentials may reflect similar changes in stiffness distributions, which could directly impact vibrational efficacy or indirectly modify sound radiation via altered damping characteristics. Either of these mechanisms may help explain the acoustical differences between the classical and modern violins.

Influence of power density on the setting behaviour of light-cured glass-ionomer cements monitored by ultrasound measurements.

Science.gov (United States)

Tonegawa, Motoka; Yasuda, Genta; Chikako, Takubo; Tamura, Yukie; Yoshida, Takeshi; Kurokawa, Hiroyasu; Miyazaki, Masashi

2009-07-01

To monitor the influence of the power density of the curing unit on the setting behaviour of light-cured glass-ionomer cements (LCGICs) using ultrasound measurements. The ultrasound equipment comprised a pulser-receiver, transducers and an oscilloscope. The LCGICs used were Fuji II LC, Fuji II LC EM and Fuji Filling LC. The cements were mixed according to the manufacturer's instructions and then inserted into a transparent mould. The specimens were placed on the sample stage and cured with power densities of 0 (no irradiation), 200 or 600 mW/cm(2). The transit time through the cement disk was divided by the specimen thickness and then the longitudinal ultrasound velocity (V) within the material was obtained. Analysis of variance and Tukey's Honestly Significantly Different test were used to compare the V values between the set cements. When the LCGICs were light-irradiated, each curve displayed an initial plateau at approximately 1500 m/s and then rapidly increased to a second plateau at approximately 2600 m/s. The rate of increase of V was retarded when the cements were light-irradiated with a power density of 200 mW/cm(2) than with a power density of 600 mW/cm(2). Although sonic echoes were detected from the beginning of the measurements, the rates of increase of the sonic velocity were relatively slow when the cement was not light-irradiated. The ultrasound device monitored the setting processes of LCGICs accurately based on the longitudinal V. The polymerization behaviour of LCGICs was shown to be affected by the power density of the curing unit.

Assessment of wood density of seven clones of Eucalyptus grandis ...

African Journals Online (AJOL)

With the objective of evaluating the correlation of wood basic density with age in seven Eucalyptus grandis clones planted in Brazil, five trees in each clone were sampled at the ages of 0, 5, 1, 5, 2, 5, 3, 5, 4, 5 and 7, 5 years. The analysis of these samples showed that the intraclonal variation of the basic density (except for 0, ...

PHYSICAL AND STRENGTH PROPERTIES OF BRICKS PRODUCED FROM PORTLAND CEMENT AND SAW DUST OF DANIELIA OLIVERII WOOD

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David Oriabure EKHUEMELO

2016-12-01

Full Text Available This study investigated the use of sawdust as partial replacement for sand in wood-concrete hollow blocks. Sharp sand, ordinary Portland cement (binder and sawdust were used as raw materials. Sawdust was treated by boiling then sieved after drying using British Standard sieve of 3.35mm to remove sticky wood capable of causing pores. The quantities of sawdust used were 0%, 5%, 10%, 15% and 20%. A mixing proportion of 1:8 cement sand ratio, moulding machine with single 6” (450mm x 225mm x 150mm mould and vibrated with 5.0KW power machine for adequate compaction were used. Wood-concrete block was cured for 28 days. The blocks produced were tested for compressive strength and water absorption. The results showed that mean compressive strength of 100% sand was 2.81N/mm2 followed by 95% sand and 5% sawdust replacement with 1.58N/mm2 ; 90% Sand and 10% sawdust replacement with 0.55N/mm2 ; 85% sand and 15% sawdust replacement with 0.43 N/mm2 and 80% sand 20% sawdust replacement with 0.24N/mm2 . The result further showed that as the percentage of sawdust increased, the compressive strength decreased. At 28 days, the compressive strength of blocks with 5% SD replacement satisfied meets Ghana Building Code for non- load bearing walls. The results also reveals that blocks with 80% sand 20% sawdust replacement level has the highest water absorption (23.72% followed by 85% Sand and 15% sawdust replacement (20.40%; 90% sand and 10% sawdust replacement (18.0%; 95% sand and 5% sawdust replacement (12.12% and 100% sand and 0% sawdust replacement (11.43%. It was concluded that 5% sawdust (8kg replacement and cured 28 days could be used for non-load bearing walls. It was recommended that further research should be carried out to evaluate sawdust replacement level within the range of 1-4% to ascertain results that could be used for various other purposes.

Physical and Strength Properties of Bricks Produced from Portland Cement and Saw Dust of Danielia Oliverii Wood

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David Oriabure EKHUEMELO

2016-12-01

Full Text Available This study investigated the use of sawdust as partial replacement for sand in wood-concrete hollow blocks. Sharp sand, ordinary Portland cement (binder and sawdust were used as raw materials. Sawdust was treated by boiling then sieved after drying using British Standard sieve of 3.35mm to remove sticky wood capable of causing pores. The quantities of sawdust used were 0%, 5%, 10%, 15% and 20%. A mixing proportion of 1:8 cement sand ratio, moulding machine with single 6” (450mm x 225mm x 150mm mould and vibrated with 5.0KW power machine for adequate compaction were used. Wood-concrete block was cured for 28 days. The blocks produced were tested for compressive strength and water absorption. The results showed that mean compressive strength of 100% sand was 2.81N/mm2 followed by 95% sand and 5% sawdust replacement with 1.58N/mm2 ; 90% Sand and 10% sawdust replacement with 0.55N/mm2 ; 85% sand and 15% sawdust replacement with 0.43 N/mm2 and 80% sand 20% sawdust replacement with 0.24N/mm2 . The result further showed that as the percentage of sawdust increased, the compressive strength decreased. At 28 days, the compressive strength of blocks with 5% SD replacement satisfied meets Ghana Building Code for non- load bearing walls. The results also reveals that blocks with 80% sand 20% sawdust replacement level has the highest water absorption (23.72% followed by 85% Sand and 15% sawdust replacement (20.40%; 90% sand and 10% sawdust replacement (18.0%; 95% sand and 5% sawdust replacement (12.12% and 100% sand and 0% sawdust replacement (11.43%. It was concluded that 5% sawdust (8kg replacement and cured 28 days could be used for non-load bearing walls. It was recommended that further research should be carried out to evaluate sawdust replacement level within the range of 1-4% to ascertain results that could be used for various other purposes.

Incorporation of waste and fiber kaolin caroa panels in Medium Density Fiberboard - MDF

International Nuclear Information System (INIS)

Bezerra, A.F.C.; Santana, L.N.L.; Neves, G.A.; Carvalho, L.H. de; Lopes, F.F.M.

2012-01-01

Medium-density panels are composites molded under high temperature and pressure which have physical and mechanical properties similar to those of solid wood. Their composition includes eucalyptus grandis fibers and pinus elliotii fibers, but other fibers can be used such as caroa fibers. The goal of this work was to manufacture panels which kaolin waste and caroa fibers and compare their physical, chemical and mechanical of these panels with a others. Both residue and the fibers were characterized by: differential thermal analysis, thermal gravimetric analysis and Xray diffraction. Through the process of pressing the test specimens were fabricated, test samples were evaluated by three point bending, internal bond, water absorption and swelling in thickness. The samples have low levels of thickness swelling, flexural strength and higher tensile and absorption content relative to commercial MDF. (author)

A Compton scattering technique to determine wood density and locating defects in it

International Nuclear Information System (INIS)

Tondon, Akash; Sandhu, B. S.; Singh, Bhajan; Singh, Mohinder

2015-01-01

A Compton scattering technique is presented to determine density and void location in the given wooden samples. The technique uses a well collimated gamma ray beam from 137 Cs along with the NaI(Tl) scintillation detector. First, a linear relationship is established between Compton scattered intensity and known density of chemical compounds, and then density of the wood is determined from this linear relation. In another experiment, the ability of penetration of gamma rays is explored to detect voids in wooden (low Z) sample. The sudden reduction in the Compton scattered intensities agrees well with the position and size of voids in the wooden sample. It is concluded that wood density and the voids of size ∼ 4 mm and more can be detected easily by this method

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

Evaluation of wood characteristics: internal scanning of the material by microwaves

International Nuclear Information System (INIS)

Martin, P.; Collet, R.; Barthelemy, P.; Roussy, G.

1987-01-01

Internal scanning of wood by microwaves presents many advantages for the automatic detection of defects and the evaluation of the characteristics of wood in the dry wood processing industries. Advantages are: access to more than one variable, efficient coupling in the air, easy automation and reasonable cost. Microwaves are electromagnetic waves the speed and attenuation of which depend of the medium in which they are propagated, especially its electric permittivity which depends on its moisture content and its density. Since wood is anisotropic, this dielectric constant also varies with the direction of fibers. An experimental apparatus was set up that allows to test the feasibility of automatic detection of wood characteristics and defects. It automatically measures the attenuation and dephasing of an ultra high frequency wave sent through a board and moving through two rotating antennas. The graphs and results obtained gave significant information of physical characteristics of wood (density, moisture content, slope of grain) and the detection of defects (knots, metallic objects, sapwood)

Wood anatomical correlates with theoretical conductivity and wood density across China: evolutionary evidence of the functional differentiation of axial and radial parenchyma.

Science.gov (United States)

Zheng, Jingming; Martínez-Cabrera, Hugo I

2013-09-01

In recent years considerable effort has focused on linking wood anatomy and key ecological traits. Studies analysing large databases have described how these ecological traits vary as a function of wood anatomical traits related to conduction and support, but have not considered how these functions interact with cells involved in storage of water and carbohydrates (i.e. parenchyma cells). We analyzed, in a phylogenetic context, the functional relationship between cell types performing each of the three xylem functions (conduction, support and storage) and wood density and theoretical conductivity using a sample of approx. 800 tree species from China. Axial parenchyma and rays had distinct evolutionary correlation patterns. An evolutionary link was found between high conduction capacity and larger amounts of axial parenchyma that is probably related to water storage capacity and embolism repair, while larger amounts of ray tissue have evolved with increased mechanical support and reduced hydraulic capacity. In a phylogenetic principal component analysis this association of axial parenchyma with increased conduction capacity and rays with wood density represented orthogonal axes of variation. In multivariate space, however, the proportion of rays might be positively associated with conductance and negatively with wood density, indicating flexibility in these axes in species with wide rays. The findings suggest that parenchyma types may differ in function. The functional axes represented by different cell types were conserved across lineages, suggesting a significant role in the ecological strategies of the angiosperms.

7 CFR 2902.42 - Wood and concrete sealers.

Science.gov (United States)

2010-01-01

... 7 Agriculture 15 2010-01-01 2010-01-01 false Wood and concrete sealers. 2902.42 Section 2902.42... Items § 2902.42 Wood and concrete sealers. (a) Definition. (1) Products that are penetrating liquids formulated to protect wood and/or concrete, including masonry and fiber cement siding, from damage caused by...

EB-curing of coatings on wood composite boards

International Nuclear Information System (INIS)

Czvikovszky, T.; Czajlic, I.; Takacs, E.; Ille, A.; Salleh, N.G.; Alpar, T.

1988-01-01

The industrial radiation processing using low energy electron beam (EB) accelerators lower than 300 keV offers high speed, safe technologies for the chemical conversion of thin layer coatings. Because of the nonselective mode of initiating chain reaction polymerization involving free radicals in synthetic coating layers and suitable substrates, the EB curing of the coatings on woods and papers has particular advantage. Hungary decided to start an up-to-date EB line to process cement-bound (CB) wood chipboards with pigmented acrylic coatings. The CB wood chipboards contain more than 60 % of portland cement and up to 40 % of wood particles. They are produced as large boads of 6 - 16 mm thickness. In their fireproof character and other aspects, they are similar to asbestos-cement boards without containing carcinagenic asbestos, and are stable against moisture and atmospheric influences. EB-cured acrylate coating improved further those properties, and makes them valuable structural material. Oligomers and monomers as the main components of EB curable coatings, the irradiation with a Van de Graaff type electron accelerator of 2 MeV and the results are reported. The oligomers play the most important role in the formation of radiation curable coatings. (K.I.)

Genetic dissection of growth, wood basic density and gene expression in interspecific backcrosses of Eucalyptus grandis and E. urophylla

Science.gov (United States)

2012-01-01

Background F1 hybrid clones of Eucalyptus grandis and E. urophylla are widely grown for pulp and paper production in tropical and subtropical regions. Volume growth and wood quality are priority objectives in Eucalyptus tree improvement. The molecular basis of quantitative variation and trait expression in eucalypt hybrids, however, remains largely unknown. The recent availability of a draft genome sequence (http://www.phytozome.net) and genome-wide genotyping platforms, combined with high levels of genetic variation and high linkage disequilibrium in hybrid crosses, greatly facilitate the detection of quantitative trait loci (QTLs) as well as underlying candidate genes for growth and wood property traits. In this study, we used Diversity Arrays Technology markers to assess the genetic architecture of volume growth (diameter at breast height, DBH) and wood basic density in four-year-old progeny of an interspecific backcross pedigree of E. grandis and E. urophylla. In addition, we used Illumina RNA-Seq expression profiling in the E. urophylla backcross family to identify cis- and trans-acting polymorphisms (eQTLs) affecting transcript abundance of genes underlying QTLs for wood basic density. Results A total of five QTLs for DBH and 12 for wood basic density were identified in the two backcross families. Individual QTLs for DBH and wood basic density explained 3.1 to 12.2% of phenotypic variation. Candidate genes underlying QTLs for wood basic density on linkage groups 8 and 9 were found to share trans-acting eQTLs located on linkage groups 4 and 10, which in turn coincided with QTLs for wood basic density suggesting that these QTLs represent segregating components of an underlying transcriptional network. Conclusion This is the first demonstration of the use of next-generation expression profiling to quantify transcript abundance in a segregating tree population and identify candidate genes potentially affecting wood property variation. The QTLs identified in this

Anatomical and chemical properties and density of Coffea arabica L. wood

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Marisa Aparecida Pereira

2014-09-01

Full Text Available The state of Minas Gerais is the largest producer of coffee in Brazil and the amount of residue in crops seems adequate to support production of solid wood products of Coffea arabica L., which is currently used for energy purposes or remains in the area. This activity adds insignificant value the coffee products and release CO2, which has harmful effects to the environment. This study was conducted with the aim of characterizing technologically Coffea arabica L. wood to enhance its use in furniture, to characterize its anatomical, chemical and wood basic density. The density showed an average of 0.608g.cm-3. The anatomical analysis showed distinct growth layers, semiporosos vessels with simple perforation plates. The axial parenchyma is apotracheal and diffuse in the aggregate with heterogeneous rays, not laminated and fiber libriformes not septate with bordered pits distinct. The chemical content of extract in hot and cold water were respectively 6.1% and 9.6%. The ash content was found to be 0.68%. Data were comparable to those of mahogany (Swietenia macrophylla and Piptadenia peregrina Benth, (angico-vermelho used for the production of furniture.

An Experimental Study of Portland Cement and Superfine Cement Slurry Grouting in Loose Sand and Sandy Soil

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Weijing Yao

2018-04-01

Full Text Available Grouting technology is widely applied in the fields of geotechnical engineering in infrastructure. Loose sand and sandy soil are common poor soils in tunnel and foundation treatments. It is necessary to use superfine cement slurry grouting in the micro-cracks of soil. The different effectiveness of Portland cement slurry and superfine cement slurry in sandy soil by the laboratory grouting experiment method were presented in this paper. The grouting situations of superfine cement slurry injected into sand and sandy soil were explored. The investigated parameters were the dry density, wet density, moisture content, internal friction angle, and cohesion force. The results show that the consolidation effect of superfine cement is better than that of Portland cement due to the small size of superfine cement particles. The superfine cement can diffuse into the sand by infiltration, extrusion, and splitting. When the water–cement ratio of superfine cement slurry is less than 2:1 grouting into loose sand, the dry and wet density decrease with the increase in the water–cement ratio, while the moisture content and cohesive force gradually increase. When the water–cement ratio of superfine cement slurry is 1:1 grouting into loose sand and sandy soil, the dry density, wet density, and cohesive force of loose sand are larger than those of sandy soil. The results of the experiment may be relevant for engineering applications.

Hydraulic architecture of two species differing in wood density: opposing strategies in co-occurring tropical pioneer trees

Science.gov (United States)

Katherine A. McCulloh; Daniel M. Johnson; Frederick C. Meinzer; Steven L. Voelker; Barbara Lachenbruch; Jean-Christophe. Domec

2012-01-01

Co-occurring species often have different strategies for tolerating daily cycles of water stress. One underlying parameter that can link together the suite of traits that enables a given strategy is wood density. Here we compare hydraulic traits of two pioneer species from a tropical forest in Panama that differ in wood density: Miconia argentea...

The variability of wood density and compression strength of Norway spruce

Czech Academy of Sciences Publication Activity Database

Horáček, Petr; Fajstavr, Marek; Stojanović, Marko

2017-01-01

Roč. 10, 1-2 (2017), s. 17-26 ISSN 1803-2451 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:86652079 Keywords : Norway spruce * wood density * compression strength * variability Subject RIV: GK - Forestry OBOR OECD: Forestry

RELATIONSHIP BETWEEN CLIMATE VARIABLES, TRUNK GROWTH RATE AND WOOD DENSITY OF Eucalyptus grandis W. Mill ex Maiden TREES

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Carlos Roberto Sette Jr

2016-04-01

Full Text Available ABSTRACT Climatic conditions stimulates the cambial activity of plants, and cause significant changes in trunk diameter growth and wood characteristics. The objective of this study was to evaluate the influence of climate variables in the diameter growth rate of the stem and the wood density of Eucalyptus grandis trees in different classes of the basal area. A total of 25 Eucalyptus trees at 22 months of age were selected according to the basal area distribution. Dendrometer bands were installed at the height of 1.30 meters (DBH to monitor the diameter growth every 14 days, for 26 months. After measuring growth, the trees were felled and wood discs were removed at the DBH level to determine the radial density profile through x-ray microdensitometry and then re-scale the average values every 14 days. Climatic variables for the monitoring period were obtained and grouped every 14 days. The effect of the climate variables was determined by maximum and minimum growth periods in assessing trunk growth. These growth periods were related with precipitation, average temperature and relative air humidity. The re-scaled wood density values, calculated using the radial growth of the tree trunks measured accurately with steel dendrometers, enabled the determination of the relationship of small changes in wood density and the effect of the climatic variations and growth rate of eucalyptus tree trunks. A high sensitivity of the wood density to variation in precipitation levels was found.

Improved prediction of hardwood tree biomass derived from wood density estimates and form factors for whole trees

Science.gov (United States)

David W. MacFarlane; Neil R. Ver Planck

2012-01-01

Data from hardwood trees in Michigan were analyzed to investigate how differences in whole-tree form and wood density between trees of different stem diameter relate to residual error in standard-type biomass equations. The results suggested that whole-tree wood density, measured at breast height, explained a significant proportion of residual error in standard-type...

Effect of wood flour content on the optical color, surface chemistry, mechanical and morphological properties of wood flour/recycled high density polyethylene (rHDPE) composite

Science.gov (United States)

Sheng, Chan Kok; Amin, Khairul Anuar Mat; Kee, Kwa Bee; Hassan, Mohd Faiz; Ali, E. Ghapur E.

2018-05-01

In this study, effect of wood flour content on the color, surface chemistry, mechanical properties and surface morphology of wood-plastic composite (WPC) on different mixture ratios of recycled high density polyethylene (rHDPE) and wood flour were investigated in detail. The presence of wood flour in the composite indicates a significant total color change and a decrease of lightness. Functional groups of wood flour in WPC can be seen clearer from the Fourier transform infrared (FTIR) spectra as the wood flour content increases. The mechanical tensile testing shows that the tensile strength of Young's modulus is improved, whereas the strain and elongation at break were reduced by the addition of wood flour. The gap between the wood flour microvoid fibre and rHDPE matrix becomes closer when the wood flour content is increased as observed by scanning electron microscope (SEM) image. This finding implies a significant improvement on the interaction of interfacial adhesion between the rHDPE matrix and wood flour filler in the present WPC.

Genetic control of wood density and bark thickness, and their ...

African Journals Online (AJOL)

Tree diameter under and over bark at breast height (dbh), wood density and bark thickness were assessed on samples from control-pollinated families of Eucalyptus grandis, E. urophylla, E. grandis × E. urophylla and E. urophylla × E. grandis. The material was planted in field trials in the coastal Zululand region of South ...

Leaf photosynthetic traits scale with hydraulic conductivity and wood density in Panamanian forest canopy trees.

Science.gov (United States)

L.S. Santiago; G. Goldstein; F.C. Meinzer; J.B. Fisher; K. Maehado; D. Woodruff; T. Jones

2004-01-01

We investigated how water transport capacity, wood density and wood anatomy were related to leaf photosynthetic traits in two lowland forests in Panama. Leaf-specific hydraulic conductivity (kL) of upper branches was positively correlated with maximum rates of net CO2, assimilation per unit leaf area (Aarea...

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.

Devolatilization and Combustion of Tire Rubber and Pine Wood in a Pilot Scale Rotary Kiln

DEFF Research Database (Denmark)

Nielsen, Anders R.; Larsen, Morten B.; Glarborg, Peter

2012-01-01

Cement production is highly energy intensive and requires large quantities of fuels. For both economical and environmental reasons, there is an increasing tendency for utilization of alternative fuels in the cement industry, examples being tire derived fuels, waste wood, or different types...... of industrial waste. In this study, devolatilization and combustion of large particles of tire rubber and pine wood with equivalent diameters of 10 mm to 26 mm are investigated in a pilot scale rotary kiln able to simulate the process conditions present in the material inlet end of cement rotary kilns...

Wood plastic composites based on microfibrillar blends of high density polyethylene/poly(ethylene terephthalate).

Science.gov (United States)

Lei, Yong; Wu, Qinglin

2010-05-01

High-melting-temperature poly(ethylene terephthalate) (PET) was successfully introduced into wood plastic composites through a two-step reactive extrusion technology. Wood flour was added into pre-prepared PET/high density polyethylene (HDPE) microfibrillar blends (MFBs) in the second extrusion at the temperature for processing HDPE. Addition of 25% in situ formed PET microfibers obviously increased the mechanical properties of HDPE, and more significant enhancement by the in situ formed recycled PET microfibers was observed for the recycled HDPE. Adding 2% E-GMA improved the compatibility between matrix and microfibers in MFBs, resulting further enhanced mechanical properties. The subsequent addition of 40% wood flour did not influence the size and morphology of PET microfibers, and improved the comprehensive mechanical properties of MFBs. The wood flour increased the crystallinity level of HDPE in the compatibilized MFB in which PET phase did not crystallize. The storage modulus of MFB was greatly improved by wood flour. Published by Elsevier Ltd.

Forest production dynamics along a wood density spectrum in eastern US forests

Science.gov (United States)

C.W. Woodall; M.B. Russell; B.F. Walters; A.W. D' Amato; K. Zhu; S.S. Saatchi

2015-01-01

Emerging plant economics spectrum theories were confirmed across temperate forest systems of the eastern US where the use of a forest stand's mean wood density elucidated forest volume and biomass production dynamics integrating aspects of climate, tree mortality/growth, and rates of site occupancy.

Umidade de equilíbrio de painéis de madeira Equilibrium moisture content of wood panels

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Graciane Angélica da Silva

2005-08-01

Full Text Available Este estudo teve como objetivo a determinação da umidade de equilíbrio de painéis de madeira numa câmara de climatização e comparação dos seus valores com os obtidos através da equação de Nelson. O trabalho foi desenvolvido na Unidade Experimental de Produção de Painéis de Madeira da Universidade Federal de Lavras. Foram utilizadas amostras de aglomerado, compensado multilaminado e sarrafeado, chapa dura, OSB (Oriented Strand Board , MDF (Medium Density Fiberboard, HDF (High Density Fiberboard, madeira-cimento e madeira-pl��stico, sendo esses produtos de escala industrial e experimental. As dimensões dos corpos-de-prova foram de 2,60 cm de largura por 2,60 cm de comprimento. As espessuras foram aquelas mais utilizadas comercialmente de cada produto, sendo utilizadas cinco repetições por painel. Os corpos-de-prova foram pesados e levados para uma câmara de climatização, onde foram submetidos a diferentes condições de umidade relativa (90, 80, 70, 60, 50 e 40% e uma temperatura constante de 30 ºC. Determinaram-se a histerese e a umidade de equilíbrio, que variaram de 40 a 90%. Os resultados indicaram que a equação de Nelson se mostrou eficiente na estimativa da umidade de equilíbrio e que não existe em média diferença de histerese entre os produtos estudados, mostrando que todos apresentam a mesma estabilidade dimensional. Observou-se, também, que o revestimento dos painéis não afetou a umidade de equilíbrio.This study aimed at determining the equilibrium moisture content of wood panels in a climatization chamber and comparing the values of equilibrium moisture content found with those given by Nelson's equation. The research was developed at the Experimental Unit of Wood Panel Production of the Universidade Federal de Lavras. Samples of particleboard, plywood, hardboard, OSB (Oriented Strand Board, MDF (Medium Density Fiberboard, HDF (High Density Fiberboard, cement wood and plastic wood were taken both from

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.

WOOD PROPERTIES AND EFFECT OF WOOD PROPERTIES ON THE WOOD FINISHING

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Abdulkadir Malkoçoğlu

2006-04-01

Full Text Available Wood is basic raw material for furniture and joinery industries with wood structures. Wood is a biological material that has widely different properties depending on species, geographic area where the tree grew, the growth condition, size of the tree at harvest, sawing, and other manufacturing processes. Wood properties have been characterized within two groups as natural and manufacturing factors that effects finishing performance. Grow rate, density, knots, moisture content, extractives and juvenile wood are natural characteristics. Grain orientation, texture, drying and performance expectations are manufacturing characteristics. In this review, the effects of natural and manufacturing characteristics are discussed on the surface finishing performance of wood.

Laboratory Investigation on Compressive Strength and Micro-structural Features of Foamed Concrete with Addition of Wood Ash and Silica Fume as a Cement Replacement

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Othuman Mydin M.A.

2014-01-01

Full Text Available Wood Ash (WA and Silica Fume (SF exhibit good cementation properties and have great potential as supplementary binder materials for the concrete production industry. This study will focus on enhancing the micro-structural formation and compressive strength of foamed concrete with the addition of WA and SF. A total of 3 mixes were prepared with the addition of WA and SF at various cement replacement levels by total binder weight. For this particular study, the combination of WA (5%, 10%, and 15% by binder weight and SF (5%, 10%, and 15% by binder weight were utilized as supplementary binder materials to produce foamed concrete mixes. As was made evident from micrographs obtained in the study, the improvement observed in the compressive strength of the foamed concrete was due to a significant densification in the microstructure of the cement paste matrix in the presence of WA and SF hybrid supplementary binders. Experimental results indicated that the combination of 15% SF and 5% WA by binder weight had a more substantial influence on the compressive strength of foamed concrete compared to the control mix. Furthermore, the addition of WA and SF significantly prolonged the setting times of the blended cement paste of the foamed concrete.

Axial variation of basic density of Araucaria angustifolia wood in different diameter classes

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Rômulo Trevisan

Full Text Available ABSTRACT: The study of the wood characteristics is of fundamental importance for the correct use of this raw material and, among its properties, the basic density is a major, being reference in the quality of this material. This study aimed to evaluate the axial variation of basic density of the wood of Araucaria angustifolia (Bertoloni O. Kuntze in different diameter classes. For this, three trees were selected in six diameter classes, called class 1 (20-30cm, class 2 (30.1-40cm, class 3 (40.1-50cm, class 4 (50.1-60cm, class 5 (60.1-70cm and class 6 (70.1-80cm. From each individual sampled was withdrawn a disc at 0.1m (base, 25, 50, 75 and 100% of the height of the first live branch and in the diameter at 1.30m from the ground (DBH, which were used for determining basic density. The weighted average basic density was equal to 0.422g cm-3 and, regardless of the diameter class analyzed, this property decreased in the axial direction. Diameter induced variation of basic density, but has not been verified a positive or negative systematic tendency in relation to the sampled interval.

Leachability of bentonite/cement for medium-level waste immobilisation

Energy Technology Data Exchange (ETDEWEB)

Hamlat, M.S.; Rabia, N. [Centre de Radioprotection et de Surete, Alger-Gare (Algeria)

1998-12-31

The release of radionuclides from Algerian bentonite/cement matrix has been measured experimentally using static and dynamic testing procedures. The waste forms were cement/sand and bentonite/cement matrices contaminated with Cs-137. To characterise radionuclide/waste form combination, two parameters, diffusion (D) and distribution coefficients ({alpha}) were used. (D) is an effective diffusion coefficient that describes the kinetic behaviour and is most easily determined using Soxhlet test, whereas, ({alpha}) describes the distribution of radionuclide between aqueous and solid phases at equilibrium and is best measured in static test. Leach rates obtained being very low. Distribution coefficient values have showed that the bentonite has relatively a high degree of fixation. It was concluded that the matrix under study seems play a role for the immobilisation. (orig.)

Leachability of bentonite/cement for medium-level waste immobilisation

International Nuclear Information System (INIS)

Hamlat, M.S.; Rabia, N.

1998-01-01

The release of radionuclides from Algerian bentonite/cement matrix has been measured experimentally using static and dynamic testing procedures. The waste forms were cement/sand and bentonite/cement matrices contaminated with Cs-137. To characterise radionuclide/waste form combination, two parameters, diffusion (D) and distribution coefficients (α) were used. (D) is an effective diffusion coefficient that describes the kinetic behaviour and is most easily determined using Soxhlet test, whereas, (α) describes the distribution of radionuclide between aqueous and solid phases at equilibrium and is best measured in static test. Leach rates obtained being very low. Distribution coefficient values have showed that the bentonite has relatively a high degree of fixation. It was concluded that the matrix under study seems play a role for the immobilisation. (orig.)

Five willow varieties cultivated across diverse field environments reveal stem density variation associated with high tension wood abundance

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Nicolas eBerthod

2015-10-01

Full Text Available Sustainable and inexpensive production of biomass is necessary to make biofuel production feasible, but represents a challenge. Five short rotation coppice (SRC willow cultivars, selected for high biomass yield, were cultivated on sites at four diverse regions of Quebec to determine their bioenergy potential in contrasting environments. Wood composition and anatomical traits were characterized. Tree height and stem diameter were measured to evaluate growth performance of the cultivars according to the diverse pedoclimatic conditions. Each cultivar showed very specific responses to its environment. While no significant variation in lignin content was observed between sites, there was variation between cultivars. Surprisingly, the pattern of substantial genotype variability in stem density was maintained across all sites. However, wood anatomy did differ between sites in a cultivar (producing high and low density wood, suggesting a probable response to an abiotic stress. Furthermore, twice as many cellulose-rich G-fibers, comprising over 50 % of secondary xylem, were also found in the high density wood, a finding with potential to bring higher value to the lignocellulosic bioethanol industry

Changes in wood density, wood anatomy and hydraulic properties of the xylem along the root-to-shoot flow path in tropical rainforest trees.

Science.gov (United States)

Schuldt, Bernhard; Leuschner, Christoph; Brock, Nicolai; Horna, Viviana

2013-02-01

It is generally assumed that the largest vessels are occurring in the roots and that vessel diameters and the related hydraulic conductance in the xylem are decreasing acropetally from roots to leaves. With this study in five tree species of a perhumid tropical rainforest in Sulawesi (Indonesia), we searched for patterns in hydraulic architecture and axial conductivity along the flow path from small-diameter roots through strong roots and the trunk to distal sun-canopy twigs. Wood density differed by not more than 10% across the different flow path positions in a species, and branch and stem wood density were closely related in three of the five species. Other than wood density, the wood anatomical and xylem hydraulic traits varied in dependence on the position along the flow path, but were unrelated to wood density within a tree. In contrast to reports from conifers and certain dicotyledonous species, we found a hump-shaped variation in vessel diameter and sapwood area--specific conductivity along the flow path in all five species with a maximum in the trunk and strong roots and minima in both small roots and twigs; the vessel size depended on the diameter of the organ. This pattern might be an adaptation to the perhumid climate with a low risk of hydraulic failure. Despite a similar mean vessel diameter in small roots and twigs, the two distal organs, hydraulically weighted mean vessel diameters were on average 30% larger in small roots, resulting in ∼ 85% higher empirical and theoretical specific conductivities. Relative vessel lumen area in percent of sapwood area decreased linearly by 70% from roots to twigs, reflecting the increase in sclerenchymatic tissue and tracheids in acropetal direction in the xylem. Vessel size was more closely related to the organ diameter than to the distance along the root-to-shoot flow path. We conclude that (i) the five co-occurring tree species show convergent patterns in their hydraulic architecture despite different growth

BASIC PROPERTIES IN RELATION TO DRYING PROPERTIES OF THREE WOOD SPECIES FROM INDONESIA

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Efrida Basri

2005-03-01

Full Text Available The objectives of this study were to investigate basic and drying properties of three wood species from Indonesia, i.e. kuda (Lannea coromandelica Merr., waru (Hibiscus tiliaceus L. and mindi besar (Melia dubia Cav.. The basic properties include density, shrinkages, modulus of rupture (MOR, compression parallel to grain (C//, wood strength and anatomical structures. Meanwhile, the drying properties included drying time and drying defects. The initial-final temperature and humidity for each species was based on defects that resulted from high temperature drying trial. The results showed that the drying properties were significantly affected by wood anatomical structure. The initial-final drybulb temperature and wetbulb depression   for kuda wood are 50 -70ºC and 3-30ºC respectively, while the corresponding figures for waru wood are 65-80ºC and 6-30ºC, and for mindi besar wood are 55-80ºC and 4-30ºC. These drying schedules, however, still need further trial prior to their implementation in the factory-scale operation. All wood species studied have density and considerable strength recommended in their use for light medium construction purposes. Mindi besar wood has decorative appearance so it is suitable for furniture.

Influence of anatomy and basic density on specific cutting force for wood from Corymbia citriodora Hill & Johnson

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Luiz-E. de L. Melo

2015-12-01

Full Text Available Aim of the study: The aim of this study was to evaluate the influence of xylem tissue cell structure, determined through biometry and basic density of the wood from Corymbia citriodora Hill & Johnson on consumption of specific 90º-0º longitudinal cutting force.Area of study: The study area was in the region of the Vale do Rio Doce - Minas Gerais, Brazil.Material and methods: A diametrical board with dimensions of 60 x 18 x 5 cm (length x width x thickness, respectively, with more than 1.3 m from the ground, was removed. In machining trials, a 400 mm diameter circular saw was used, with 24 “WZ” teeth, feed rate of 10 m.min-1, cutting speed of 61 m.s-1, and maximum instantaneous torque of 92.5 N.m. During cutting, test specimens were removed with alternated and parallel 1.5 cm edges in 6 radial positions, which were used for biometric determination of cell structure and basic density.Main results: It was observed that wood basic density, vessel diameter, fiber wall thickness, fiber wall fraction and fiber wall portion were directly proportional to the specific cutting force. In contrast, vessel frequency and fiber lumen diameter proved to be inversely proportional to cutting force.Research highlights: This work provides important values of quantification of influence of xylem tissue cell structure, determined through biometry and physical properties of the wood that may be used to prediction of consumption of specific cutting force.Keywords: wood machining; wood properties; optimization of the process.

A critical analysis of methods for rapid and nondestructive determination of wood density in standing trees

Science.gov (United States)

Shan Gao; Xiping Wang; Michael C. Wiemann; Brian K. Brashaw; Robert J. Ross; Lihai Wang

2017-01-01

Key message Field methods for rapid determination of wood density in trees have evolved from increment borer, torsiometer, Pilodyn, and nail withdrawal into sophisticated electronic tools of resistance drilling measurement. A partial resistance drilling approach coupled with knowledge of internal tree density distribution may...

Sulfur Release from Cement Raw Materials during Solid Fuel Combustion

DEFF Research Database (Denmark)

Nielsen, Anders Rooma; Larsen, Morten B.; Glarborg, Peter

2011-01-01

During combustion of solid fuels in the material inlet end of cement rotary kilns, local reducing conditions can occur and cause decomposition of sulfates from cement raw materials. Decomposition of sulfates is problematic because it increases the gas-phase SO2 concentration, which may cause...... deposit formation in the kiln system. SO2 release from cement raw materials during combustion of solid fuels has been studied experimentally in a high temperature rotary drum. The fuels were tire rubber, pine wood, petcoke, sewage sludge, and polypropylene. The SO2 release from the raw materials...

Biophysical modelling of intra-ring variations in tracheid features and wood density of Pinus pinaster trees exposed to seasonal droughts.

Science.gov (United States)

Wilkinson, Sarah; Ogée, Jérôme; Domec, Jean-Christophe; Rayment, Mark; Wingate, Lisa

2015-03-01

Process-based models that link seasonally varying environmental signals to morphological features within tree rings are essential tools to predict tree growth response and commercially important wood quality traits under future climate scenarios. This study evaluated model portrayal of radial growth and wood anatomy observations within a mature maritime pine (Pinus pinaster (L.) Aït.) stand exposed to seasonal droughts. Intra-annual variations in tracheid anatomy and wood density were identified through image analysis and X-ray densitometry on stem cores covering the growth period 1999-2010. A cambial growth model was integrated with modelled plant water status and sugar availability from the soil-plant-atmosphere transfer model MuSICA to generate estimates of cell number, cell volume, cell mass and wood density on a weekly time step. The model successfully predicted inter-annual variations in cell number, ring width and maximum wood density. The model was also able to predict the occurrence of special anatomical features such as intra-annual density fluctuations (IADFs) in growth rings. Since cell wall thickness remained surprisingly constant within and between growth rings, variations in wood density were primarily the result of variations in lumen diameter, both in the model and anatomical data. In the model, changes in plant water status were identified as the main driver of the IADFs through a direct effect on cell volume. The anatomy data also revealed that a trade-off existed between hydraulic safety and hydraulic efficiency. Although a simplified description of cambial physiology is presented, this integrated modelling approach shows potential value for identifying universal patterns of tree-ring growth and anatomical features over a broad climatic gradient. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The effect of planting density on the wood quality of South African ...

African Journals Online (AJOL)

This paper presents the results of a wood property and sawn board quality study performed on disc samples and sawlogs taken from a 23-year-old Eucalyptus grandis Nelder 1a spacing trial at J.D.M. Keet plantation near Tzaneen. Ten trees from each of four markedly different planting densities were chosen to provide ...

Experimental Investigation and Taguchi Optimisation of Drilling Properties on Teak Wood Reinforced Epoxy Resin

Science.gov (United States)

Lilly Mercy, J.; Shaqir Tanvir, Mohamed; Swaroopkanth, K.

2017-05-01

The drilling properties of teak reinforced epoxy resin composite are explored in this work. The thrust force and temperature during the drilling process was found and optimised. Nine holes were drilled in accordance with L9 orthogonal array on Medium Density Fibre board and Teak wood reinforced epoxy composite board and the thrust force and temperature induced during drilling is measured. Drilling experiments were conducted using CNC Vertical drilling machine and the thrust force was measured using dynamometer and temperature using infra-red thermometer. The experiments were conducted with varying levels of spindle speed and feed rate and optimised using Taguchi optimisation. It was observed that higher thrust and temperature were observed while drilling teak wood composite due to the high mechanical strength of teak wood. The hard and brittle properties of the resin seemed to be more pronounced in the composite. The experimental results were optimised to find the best combination of input parameters for reduced thrust and temperature. When speed increases, thrust force decreases and temperature increases. When feed increases, thrust force increases and temperature decreases. Experimental findings encouragesto use teak wood reinforced epoxy resin as a substitute for the traditionally used Medium Density Fibre Board. The percentage of mixing of teak dust can be increased with various resin combinations to arrive at the best suitable combination for obtaining optimal mechanical properties.

Ultrafine portland cement performance

Directory of Open Access Journals (Sweden)

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.

Cement radwaste solidification studies third annual report

International Nuclear Information System (INIS)

Brown, D.J.; James, J.M.; Lee, D.J.; Smith, D.L.; Walker, A.T.

1982-03-01

This report summarises cement radwaste studies carried out at AEE Winfrith during 1981 on the encapsulation of medium and low active waste in cement. During the year more emphasis has been placed on the work which is directly related to the solidification of SGHWR active sludge. Information has been obtained on the properties of 220 dm 3 drums of cemented waste. The use of cement grouts for the encapsulation of solid items has also been investigated during 1981. (U.K.)

Assessment of the wood waste resource and its position in the wood / wood-energy sector - Synthesis

International Nuclear Information System (INIS)

Guinard, Ludovic; Deroubaix, Gerard; Roux, Marie-Lise; Levet, Anne-Laure; Quint, Vincent

2015-04-01

The first objective of this study is to obtain a better knowledge of the 'wood wastes' issue, to propose a photography of the wood waste sector (productions, trades, consumptions), and then to elaborate different prospective scenarios on the use of wood waste volumes while taking into account possible evolutions on the medium or short term of the regulation and market of the wood/wood energy sector. The considered wastes come from industrial production, from the use of wood-based products, and from the end of life of products potentially containing wood. The authors present bibliographical sources and the adopted methodology, briefly describe the 'wood waste' system with its actors, and then report their assessment of wood wastes. They propose a global assessment as well as detailed assessments with respect to waste origins: wood trade and distribution, industries, craft, households and communities, building sector, public and private tertiary sector, packaging. They also address the collection and management of wood wastes by public services, and present the different types of valorisation (panel fabrication, energy, and others). They discuss exports, and then present different scenarios: a trend-based scenario, and two prospective scenarios with a priority to energetic valorisation or to material valorisation of wood wastes. These scenarios are compared

Influence of Silica Fume Addition in the Long-Term Performance of Sustainable Cement Grouts for Micropiles Exposed to a Sulphate Aggressive Medium

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José Marcos Ortega

2017-08-01

Full Text Available At present, sustainability is of major importance in the cement industry, and the use of additions such as silica fume as clinker replacement contributes towards that goal. Special foundations, and particularly micropiles, are one of the most suitable areas for the use of sustainable cements. The aim of this research is to analyse the effects in the very long-term (for 600 days produced by sulphate attack in the microstructure of grouts for micropiles in which OPC (ordinary Portland cement has been replaced by 5% and 10% silica fume. This line of study is building on a previous work, where these effects were studied in slag and fly ash grouts. Grouts made using a commercial sulphate-resisting Portland cement were also studied. The non-destructive impedance spectroscopy technique, mercury intrusion porosimetry, and Wenner resistivity testing were used. Mass variation and the compressive strength have also been analysed. Apparently, impedance spectroscopy is the most suitable technique for studying sulphate attack development. According to the results obtained, grouts for micropiles with a content of silica fume up to 10% and exposed to an aggressive sulphate medium, have a similar or even better behaviour in the very long-term, compared to grouts prepared using sulphate-resisting Portland cement.

Ecological sanitation in urban medium density mixed housing

CSIR Research Space (South Africa)

Matsebe, G

2011-07-01

Full Text Available are unique to the use of Ecosan in urban Medium-Density Mixed-Housing (MDMH). Firstly, decision-making is more complex because consensus needs to be reached among a diverse group of people with a varied level of understanding of ecological and sustainable...

Integrated control of wood destroying basidiomycetes combining Cu-based wood preservatives and Trichoderma spp.

Science.gov (United States)

Ribera, Javier; Fink, Siegfried; Bas, Maria Del Carmen; Schwarze, Francis W M R

2017-01-01

The production of new generation of wood preservatives (without addition of a co-biocide) in combination with an exchange of wood poles on identical sites with high fungal inoculum, has resulted in an increase of premature failures of wood utility poles in the last decades. Wood destroying basidiomycetes inhabiting sites where poles have been installed, have developed resistance against wood preservatives. The objective of the in vitro studies was to identify a Trichoderma spp. with a highly antagonistic potential against wood destroying basidiomycetes that is capable of colonizing Cu-rich environments. For this purpose, the activity of five Trichoderma spp. on Cu-rich medium was evaluated according to its growth and sporulation rates. The influence of the selected Trichoderma spp. on wood colonization and degradation by five wood destroying basidiomycetes was quantitatively analyzed by means of dry weight loss of wood specimens. Furthermore, the preventative effect of the selected Trichoderma spp. in combination with four Cu-based preservatives was also examined by mass loss and histological changes in the wood specimens. Trichoderma harzianum (T-720) was considered the biocontrol agent with higher antagonistic potential to colonize Cu-rich environments (up to 0.1% CuSO4 amended medium). T. harzianum demonstrated significant preventative effect on wood specimens against four wood destroying basidiomycetes. The combined effect of T. harzianum and Cu-based wood preservatives demonstrated that after 9 months incubation with two wood destroying basidiomycetes, wood specimens treated with 3.8 kg m-3 copper-chromium had weight losses between 55-65%, whereas containers previously treated with T. harzianum had significantly lower weight losses (0-25%). Histological studies on one of the wood destroying basidiomycetes revealed typical decomposition of wood cells by brown-rot fungi in Cu-impregnated samples, that were notably absent in wood specimens previously exposed to T

Integrated control of wood destroying basidiomycetes combining Cu-based wood preservatives and Trichoderma spp.

Directory of Open Access Journals (Sweden)

Javier Ribera

Full Text Available The production of new generation of wood preservatives (without addition of a co-biocide in combination with an exchange of wood poles on identical sites with high fungal inoculum, has resulted in an increase of premature failures of wood utility poles in the last decades. Wood destroying basidiomycetes inhabiting sites where poles have been installed, have developed resistance against wood preservatives. The objective of the in vitro studies was to identify a Trichoderma spp. with a highly antagonistic potential against wood destroying basidiomycetes that is capable of colonizing Cu-rich environments. For this purpose, the activity of five Trichoderma spp. on Cu-rich medium was evaluated according to its growth and sporulation rates. The influence of the selected Trichoderma spp. on wood colonization and degradation by five wood destroying basidiomycetes was quantitatively analyzed by means of dry weight loss of wood specimens. Furthermore, the preventative effect of the selected Trichoderma spp. in combination with four Cu-based preservatives was also examined by mass loss and histological changes in the wood specimens. Trichoderma harzianum (T-720 was considered the biocontrol agent with higher antagonistic potential to colonize Cu-rich environments (up to 0.1% CuSO4 amended medium. T. harzianum demonstrated significant preventative effect on wood specimens against four wood destroying basidiomycetes. The combined effect of T. harzianum and Cu-based wood preservatives demonstrated that after 9 months incubation with two wood destroying basidiomycetes, wood specimens treated with 3.8 kg m-3 copper-chromium had weight losses between 55-65%, whereas containers previously treated with T. harzianum had significantly lower weight losses (0-25%. Histological studies on one of the wood destroying basidiomycetes revealed typical decomposition of wood cells by brown-rot fungi in Cu-impregnated samples, that were notably absent in wood specimens

Cements in radioactive waste management. Characterization requirements of cement products for acceptance and quality assurance purposes

International Nuclear Information System (INIS)

Rahman, A.A.; Glasser, F.P.

1987-01-01

Cementitious materials are used as immobilizing matrices for low (LLW) and medium-level wastes (MLW) and are also components of the construction materials in the secondary barriers and the repositories. This report has concerned itself with a critical assessment of the quality assurance aspects of the immobilization and disposal of MLW and LLW cemented wastes. This report has collated the existing knowledge of the use and potential of cementitious materials in radioactive waste immobilization and highlighted the physico-chemical parameters. Subject areas include an assessment of immobilization objectives and cement as a durable material, waste stream and matrix characterization, quality assurance concepts, nature of cement-based systems, chemistry and modelling of cement hydration, role and effect of blending agents, radwaste-cement interaction, assessment of durability, degradative and radiolytic processes in cements and the behaviour of cement-based matrices and their near-field interactions with the environment and the repository conditions

Wood waste: A disposal problem or an opportunity?

International Nuclear Information System (INIS)

Vajda, P.

1989-01-01

The utilization of wood wastes in North America is reviewed, with a focus on the wood products industry and markets. On the whole, wood mill residues in North America have always been utilized except for a period from the 1940s to the 1970s oil crisis. In the latter period, low cost electric power and hydrocarbon fuels rendered uneconomical the use of wood wastes as fuel. As a response to the problem of disposing these wastes, a number of innovations occurred in that period, including the use of wood chips for manufacturing pulp and particleboard, and the use of sawdust and shavings for manufacturing hardboard and medium density fiberboard. Uses for bark, except as fuel, have not been successfully developed. Since the 1970s, wood waste in the USA is essentially all used for composite board products and fuel. This is also true in eastern Canada, which is close to the wood products markets and which has fairly high oil and gas costs. However, in western Canada, low energy costs and small internal markets have led to a serious wood waste disposal problem. A survey of wood waste supply and demand shows large surpluses in mill residues in western Canada and some remote locations in northern Ontario and Quebec. The Pacific Rim countries are identified as a potential market for western Canadian composite board production. The use of other sources of wood waste (forestry or logging residues, which are costly to collect, and municipal construction waste) is briefly discussed

Addition of 1, 2 and 3% in mass of sodium alginate in calcium phosphate cement

International Nuclear Information System (INIS)

Coelho, W.T.; Fernandes, J.M.; Vieira, R.S.; Thurmer, M.B.; Santos, L.A.

2011-01-01

The calcium phosphate cement (CFC) are bone substitutes with great potential for use in orthopedics, traumatology and dentistry because of their biocompatibility, bioactivity, osteoconductivity and osteotransdutivity, and a paste that can be easily molded and placed into the surgical site. However, CFCs have low mechanical strength, which equals the maximum mechanical strength of trabecular bone. Aiming to evaluate the strength and time to handle a CFC phase composed mainly of alpha were added to sodium alginate (1%, 2% and 3% wt) and an accelerator handle in an aqueous medium. The cement powder was mixed with liquid takes 2 minutes and resigned in specimens and assessed for apparent density and porosity by the Archimedes method, X-ray diffraction and mechanical strength. We noticed a significant increase in mechanical properties of cement added sodium alginate. (author)

Examination of the constancy of the medium optical density of conventional chest radiographs

International Nuclear Information System (INIS)

Stieve, F.E.; Rupp, N.; Niederhofer, F.; Gfirtner, H.

2002-01-01

Purpose: To determine whether the medium optical density of conventional chest radiographs is constant. Materials and Methods: 47 PA chest radiographs were digitized to measure the optical density and its dynamic range of normal and pathologically altered lungs. Results: For constant exposure factors and a correctly positioned region of interest, the medium optical density deviates only minimal despite differences in AP chest diameter, entry dose and dynamic range, and is largely independent of the pathologic pulmonary findings. Conclusion: Digitization of the radiograph enables the determination of the physical parameters used to operate the imaging system, such as medium optical density, image contrast, image latitude and density distribution, in accordance to the guidelines of the German Medical Association. If the region of interest encompasses the clinically relevant region of the lung, the measured value of the optical density corresponds with only minor variation to the average value of the entire lung region. (orig.) [de

A Review of Wood Plastic Composites effect on the Environment

Directory of Open Access Journals (Sweden)

Ahmed Taifor Azeez

2017-05-01

Full Text Available Wood Plastic Composites (WPCs are environmentally friend materials with a wide range of applications in the field of constructions, comprising high mechanical and physical properties with low cost raw materials as plastic wastes and different carpentry process wood reminder. The effects of wood, plastic waste and additives on various properties of the material such as mechanical (modulus of elasticity and modulus of rupture, physical (moisture absorption and fire retardancy have been investigated in order to push the output functions of the products to the limits of work conditions requirements. This study, overviews the importance of Wood Plastic Composites in conserving the environment by depletion post consume plastics from landfills, and the impact of these composites in developing the economic via opening new flourished markets for modern products. Both the ecological and economical requirements oblige the Iraqi government to replace the negatively healthy effects formaldehyde wood composites (medium density fiberboard MDF which are widely consumed in Iraqi markets with Wood Plastic Composites. a long-term strategy plan in which the researchers and the capitals meet under supervision of the government is very necessary and recommended in this paper to establish and develop WPCs industry in Iraq.

Compressive Strength and Physical Properties Behavior of Cement Mortars with addition of Cement Klin Dust

OpenAIRE

Auday A Mehatlaf

2017-01-01

Cement Klin Dust (CKD) was the waste of almost cement industry factories, so that in this paper utilization of CKD as filler in cement and/or concrete was the main objective. CKD from the Karbala cement factory had been used and analysis to know the chemical composition of the oxides was done. In this paper cement mortars with different weight percentages of CKD (0,5,10,20,30,40) had been prepared. Physical properties such as density and porosity were done in different age curing (3, 7, 28) d...

Phenolics as Mediators to Accelerate the Enzymatically Initialized Oxidation of Laccase-Mediator-Systems for the Production of Medium Density Fiberboards

Directory of Open Access Journals (Sweden)

Alexander Kirsch

2016-07-01

Full Text Available Crude oil as a non-renewable resource is creating new challenges in many industrial sectors. Unsteady costs of crude oil at present and expected increases in the future are due to its limited availability as a finite resource, and these costs negatively impact the industry for wood-based panels, which use petrochemical resins in binding agents. Furthermore, wood panels that are conventionally bonded using urea formaldehyde diffuse formaldehyde into the surrounding air. To achieve independence from petrochemical products and harmful formaldehyde emissions, alternatives for their substitution are in demand. An alternative approach is the enzymatic activation of lignin located on the surface of thermomechanical pulp (TMP fibers. The present study shows the results of internal bond strength (DIN EN 319 1993, modulus of rupture (DIN EN 310 1993, and thickness swelling (EN 317 2003 of medium-density fiberboards (MDF bonded with laccase-mediator-system (LMS. Caffeic acid (CA, 4-hydoxy benzoic acid (HBA, and vanillic alcohol (VAl were used as mediators. The physical and technological properties of MDF, such as internal bond strength, modulus of rupture, and thickness swelling, mostly fulfilled the European standards.

Impact of implant size on cement filling in hip resurfacing arthroplasty.

Science.gov (United States)

de Haan, Roel; Buls, Nico; Scheerlinck, Thierry

2014-01-01

Larger proportions of cement within femoral resurfacing implants might result in thermal bone necrosis. We postulate that smaller components are filled with proportionally more cement, causing an elevated failure rate. A total of 19 femoral heads were fitted with polymeric replicas of ReCap (Biomet) resurfacing components fixed with low-viscosity cement. Two specimens were used for each even size between 40 and 56 mm and one for size 58 mm. All specimens were imaged with computed tomography, and the cement thickness and bone density were analyzed. The average cement mantle thickness was 2.63 mm and was not correlated with the implant size. However, specimen with low bone density had thicker cement mantles regardless of size. The average filling index was 36.65% and was correlated to both implant size and bone density. Smaller implants and specimens with lower bone density contained proportionally more cement than larger implants. According to a linear regression model, bone density but not implant size influenced cement thickness. However, both implant size and bone density had a significant impact on the filling index. Large proportions of cement within the resurfacing head have the potential to generate thermal bone necrosis and implant failure. When considering hip resurfacing in patients with a small femoral head and/or osteoporotic bone, extra care should be taken to avoid thermal bone necrosis, and alternative cementing techniques or even cementless implants should be considered. This study should help delimiting the indications for hip resurfacing and to choose an optimal cementing technique taking implant size into account.

Bone density and anisotropy affect periprosthetic cement and bone stresses after anatomical glenoid replacement: A micro finite element analysis.

Science.gov (United States)

Chevalier, Yan; Santos, Inês; Müller, Peter E; Pietschmann, Matthias F

2016-06-14

Glenoid loosening is still a main complication for shoulder arthroplasty. We hypothesize that cement and bone stresses potentially leading to fixation failure are related not only to glenohumeral conformity, fixation design or eccentric loading, but also to bone volume fraction, cortical thickness and degree of anisotropy in the glenoid. In this study, periprosthetic bone and cement stresses were computed with micro finite element models of the replaced glenoid depicting realistic bone microstructure. These models were used to quantify potential effects of bone microstructural parameters under loading conditions simulating different levels of glenohumeral conformity and eccentric loading simulating glenohumeral instability. Results show that peak cement stresses were achieved near the cement-bone interface in all loading schemes. Higher stresses within trabecular bone tissue and cement mantle were obtained within specimens of lower bone volume fraction and in regions of low anisotropy, increasing with decreasing glenohumeral conformity and reaching their maxima below the keeled design when the load is shifted superiorly. Our analyses confirm the combined influences of eccentric load shifts with reduced bone volume fraction and anisotropy on increasing periprosthetic stresses. They finally suggest that improving fixation of glenoid replacements must reduce internal cement and bone tissue stresses, in particular in glenoids of low bone density and heterogeneity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Predicting the density of structural timber members in service. The combine use of wood cores and drill resistance data

Directory of Open Access Journals (Sweden)

Morales-Condea, M. J.

2014-09-01

Full Text Available Drilling devices is used to get information about the cross-section properties and internal defects of structural members. Drill resistance is correlated with density which is often used to predict the mechanical properties of timber elements. However in situ a regression curve cannot be obtained and pre-existent curves provides unreliable predictions. The present paper proposes a procedure for in situ “calibration” of drill resistance data. The “calibration” is based on density values from wood cores taken in the close vicinity of drill holes. Two approaches were tested. One approach based on a regression curve built using wood cores density and drill resistance values obtained from a limited number of members. The other approach uses the information of one wood core to “calibrate” the drill resistance profile taken at the same member. Following this procedure a density prediction is obtained showing a low mean percentage error and a medium coefficient of determination.Los dispositivos de perforación se utilizan a menudo para obtener información sobre las propiedades de la sección transversal y defectos internos de los elementos estructurales de madera. La resistencia a la perforación se correlaciona con la densidad que, a menudo, se utiliza para obtener la predicción de las propiedades mecánicas de los elementos de madera. Sin embargo, una curva de regresión no puede ser obtenida in situ y las curvas de preexistentes proporcionan predicciones poco fiables. En el presente trabajo se propone un procedimiento de “calibración” in situ de los datos de resistencia de perforación obtenidos en cada caso. La “calibración” se basa en los valores de densidad de pequeñas probetas de madera tomadas en las inmediaciones de los taladros. Para ello se plantean 2 métodos: Un primer enfoque basado en obtener una curva de regresión a partir de los valores de densidad de pequeñas probetas de madera y los valores de resistencia a

Fruit production and branching density affect shoot and whole-tree wood to leaf biomass ratio in olive.

Science.gov (United States)

Rosati, Adolfo; Paoletti, Andrea; Al Hariri, Raeed; Famiani, Franco

2018-02-14

The amount of shoot stem (i.e., woody part of the shoot) dry matter per unit shoot leaf dry matter (i.e., the shoot wood to leaf biomass ratio) has been reported to be lower in short shoots than in long ones, and this is related to the greater and earlier ability of short shoots to export carbon. This is important in fruit trees, since the greater and earlier carbon export ability of shoots with a lower wood to leaf biomass ratio improves fruit production. This ratio may vary with cultivars, training systems or plant age, but no study has previously investigated the possible effect of fruit production. In this study on two olive cultivars (i.e., Arbequina, with low growth rate, and Frantoio, with high growth rate) subject to different fruit production treatments, we found that at increasing fruit production, shoot length and shoot wood to leaf biomass ratio were proportionally reduced in the new shoots growing at the same time as the fruit. Specifically, fruit production proportionally reduced total new-shoot biomass, length, leaf area and average shoot length. With decreasing shoot length, shoot diameter, stem mass, internode length, individual leaf area and shoot wood to leaf biomass ratio also decreased. This may be viewed as a plant strategy to better support fruit growth in the current year, given the greater and earlier ability of short shoots to export carbon. Moreover, at the whole-tree level, the percentage of total tree biomass production invested in leaves was closely correlated with branching density, which differed significantly across cultivars. By branching more, Arbequina concentrates more shoots (thus leaves) per unit of wood (trunk, branches and root) mass, decreasing wood to leaf biomass ratio at the whole-tree level. Therefore, while, at the shoot level, shoot length determines shoot wood to leaf biomass ratio, at the canopy level branching density is also an important determinant of whole-tree wood to leaf biomass ratio. Whole-tree wood to leaf

Application of precise MPD & pressure balance cementing technology

Directory of Open Access Journals (Sweden)

Yong Ma

2018-03-01

Full Text Available The precise managed pressure drilling (MPD technology is mainly used to deal with the difficulties encountered when oil and gas open hole sections with multiple pressure systems and the strata with narrow safety density window are drilled through. If its liner cementing is carried out according to the conventional method, lost circulation is inevitable in the process of cementing while the displacement efficiency of small-clearance liner cementing is satisfied. If the positive and inverse injection technology is adopted, the cementing quality cannot meet the requirements of later well test engineering of ultradeep wells. In this paper, the cementing operation of Ø114.3 mm liner in Well Longgang 70 which was drilled in the Jiange structure of the Sichuan Basin was taken as an example to explore the application of the cementing technology based on the precise MPD and pressure balancing method to the cementing of long open-hole sections (as long as 859 m with both high and low pressures running through multiple reservoirs. On the one hand, the technical measures were taken specifically to ensure the annulus filling efficiency of slurry and the pressure balance in the whole process of cementing. And on the other hand, the annulus pressure balance was precisely controlled by virtue of precise MPD devices and by injecting heavy weight drilling fluids through central pipes, and thus the wellbore pressure was kept steady in the whole process of cementing in the strata with narrow safety density window. It is indicated that Ø114.3 mm liner cementing in this well is good with qualified pressure tests and no channeling emerges at a funnel during the staged density reduction. It is concluded that this method can enhance the liner cementing quality of complex ultradeep gas wells and improve the wellbore conditions for the later safe well tests of high-pressure gas wells. Keywords: Ultradeep well, Liner cementing, Narrow safety density window, Precise

Differential growth responses to water balance of coexisting deciduous tree species are linked to wood density in a Bolivian tropical dry forest.

Science.gov (United States)

Mendivelso, Hooz A; Camarero, J Julio; Royo Obregón, Oriol; Gutiérrez, Emilia; Toledo, Marisol

2013-01-01

A seasonal period of water deficit characterizes tropical dry forests (TDFs). There, sympatric tree species exhibit a diversity of growth rates, functional traits, and responses to drought, suggesting that each species may possess different strategies to grow under different conditions of water availability. The evaluation of the long-term growth responses to changes in the soil water balance should provide an understanding of how and when coexisting tree species respond to water deficit in TDFs. Furthermore, such differential growth responses may be linked to functional traits related to water storage and conductance. We used dendrochronology and climate data to retrospectively assess how the radial growth of seven coexisting deciduous tree species responded to the seasonal soil water balance in a Bolivian TDF. Linear mixed-effects models were used to quantify the relationships between basal area increment and seasonal water balance. We related these relationships with wood density and sapwood production to assess if they affect the growth responses to climate. The growth of all species responded positively to water balance during the wet season, but such responses differed among species as a function of their wood density. For instance, species with a strong growth response to water availability averaged a low wood density which may facilitate the storage of water in the stem. By contrast, species with very dense wood were those whose growth was less sensitive to water availability. Coexisting tree species thus show differential growth responses to changes in soil water balance during the wet season. Our findings also provide a link between wood density, a trait related to the ability of trees to store water in the stem, and wood formation in response to water availability.

Comparative analysis of compressive strength tests at age of 28 and 90 days and density of products using chemical additives in cementing radioactive waste

International Nuclear Information System (INIS)

Vieira, Vanessa Mota; Tello, Cledola Cassia Oliveira de

2013-01-01

In this research it has been studied the effects of chemical additives (admixtures) in the cementation process of radioactive wastes, which are used to improve the properties of waste cementation process, both of the paste and of the solidified product. However there are a large variety of these materials that are frequently changed or taken out of the market, then it is essential to know the commercially available materials and their effects. The tests were carried out with a solution simulating the evaporator concentrate waste coming from PWR nuclear reactors. It was cemented using two formulations, A and B, incorporating higher or lower amount of waste, respectively. It was added chemical admixtures from two manufacturers (S and H), which were: accelerators, set retarders and superplasticizers. The experiments were organized by a factorial design 2 3 . The measured parameters were the viscosity, the setting time, the paste and product density and the compressive strength. In this study we performed comparative analyzes of the results of compressive strength at age of 28 and 90 days and between the densities of the samples at the same ages.The compressive strength test at age of 28 days is considered a parameter essential issues related to security handling, transport and storage of cemented waste product. The results showed that the addition of accelerators improved the compressive strength of the cemented product, but presented lower values density products. (author)

Characteristic of Polymer-Impregnated Cement Mortar: Composites: Bulk Density and Microstructure

International Nuclear Information System (INIS)

Younes, M.M.; Abo-El-Enein, S.A.; El-Saft, M.M.; Sadek, M.A.; Zohdy, K.M.

2010-01-01

The effect of radiation initiated polymerization of some monomers on the physical properties of polymer-incorporated mortar was studied. The monomers used were: castor oil (C.O.), 4, 4'-diphenylmethane diisocyanate (MDI) and methyl methacrylate (MMA). Polymerization was carried out by subjecting the monomer-impregnated mortar specimens to different doses of gamma radiation. Where polyurethane (pu) and polyurethane -methyl methacrylate copolymers were formed within the pore system. The influence of polymer impregnation on the various physico-mechanical characteristics of the resulting composites was studied with respect to bulk density and polymer loading. Scanning electron microscopy (SEM) was employed to study the micro-structural characteristics of the neat hardened Ordinary Portland Cement (OPC) mortar pastes and their polymer-impregnated composites

X-ray measurements on wood - spectra measurements

DEFF Research Database (Denmark)

Jensen, Signe Kamp; Thygesen, Lisbeth Garbrecht; Gerward, Leif

The report concerns simultaneous non-destructive measurements of water content and density of wood. Theoretically, this should be possible using a x-ray equipment newly build at BKM, and this work is an attempt to use the equipment for assessing water content and density of wood samples under...... laboratory conditions. A number of wood samples with different densities are placed at different relative humidities from 0.5 to 97 %RH. When equilibrium is obtained the samples are measured with the x-ray equipment such that 10 points are measured in the sample followed by measurements outside the sample...... (free-scanning). In this way 100 points are measured for each wood sample. This produces information about moisture content and density of the samples as water and wood attenuations of the x-rays are different for the different energy levels contained in the x-rays. The "real" density and moisture...

A NOVEL FIRE RETARDANT AFFECTS FIRE PERFORMANCE AND MECHANICAL PROPERTIES OF WOOD FLOUR-HIGH DENSITY POLYETHYLENE COMPOSITES

Directory of Open Access Journals (Sweden)

Mingzhu Pan,

2012-02-01

Full Text Available Wood flour-high density polyethylene (HDPE composites were prepared to investigate the effects of ammonium polyphosphate based fire retardant content (2, 4, 6, 8, and 10-wt%, on the flammability, mechanical, and morphological properties of the wood flour-HDPE composites in this study. Cone calorimetry analysis showed that the addition of fire retardant could decrease the heat release rate (HRR and total smoke release of wood flour-HDPE composites, while it had no obviously effects on effective heat of combustion. Most of the decrease of the HRR occurred with the concentration of the fire retardant up to 4-wt%. With addition of fire retardant, the composites showed a decrease in tensile elongation at break and impact strength, and had no obvious effect on tensile and flexural strength. The scanning electron microscopy observation on the fracture surface of the composites indicated that fire retardant had a uniform dispersion in the wood flour-HDPE composites. However, interfacial bonding would be suggested to improve in wood flour-HDPE composites with ammonium polyphosphate based fire retardant.

The use of mexican cements in the low and medium radioactive wastes confinement

International Nuclear Information System (INIS)

Badillo A, V.E.; Almazan T, M.G.; Alonso V, G.; Palacios H, J.C.

2008-01-01

Inside the relative mark to the radioactive waste confinement, minerals of great fixation capacity like clays, apatites and diverse oxides are studied as matrixes, components and/or additives of the active barriers that separate the barrier geologic and the nuclear wastes. In this case, the cements intervene in those different stages of the waste management, since its are used for the immobilization of radioactive waste in the container, for the production of containers as well as filler of the spaces among the containers of the vaults, and also as engineering barrier and construction material in the civil work. For the above mentioned, it is particularly useful to characterize the Portland cements with at least 97% of clinker, since they are most recommended for this type of applications. Presently investigation work is carried out a preliminary chemical characterization, based on the mineralogical composition, of the Portland Mexican cement. Results are shown by the X-ray Diffraction technique when immobilizing a rich solution in sulfates to 5%, using two Portland commercial cements APASCO and TOLTECA, without observing the significant appearance of new phases. The cements besides incorporating the chemical species in the breast of the matrix, are also present as barriers of civil engineering in the facilities located only some meters deep for the storage of radioactive waste of low and intermediate level, for that the study of the radionuclides fixation, in the cements is of supreme importance to evaluate the safety of a nuclear repository with the help of cements; the retention of the iodine-131 in a limited interval of pH in the commercial APASCO and TOLTECA it was studied, being observed a scarce retention of this homologous of fission products, what indicates the necessity to use additives to improve the retention properties of the Mexican commercial cements for some radionuclides. (Author)

Modeling and Optimization of the Thermal Performance of a Wood-Cement Block in a Low-Energy House Construction

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Iole Nardi

2016-08-01

Full Text Available The reduction of building energy consumption requires appropriate planning and design of the building’s envelope. In the last years, new innovative materials and construction technologies used in new or refurbished buildings have been developed in order to achieve this objective, which are also needed for reducing greenhouse gases emissions and building maintenance costs. In this work, the thermal conductance of a brick, made of wood and cement, used in a low-rise building, was investigated with a heat flow meter (HFM and with numerical simulation using the Ansys® software package (Canonsburg, PA, USA. Due to their influence on the buildings’ thermal efficiency, it is important to choose an appropriate design for the building blocks. Results obtained by the finite element modeling of the construction material and by in-situ analysis conducted on a real building are compared, and furthermore a thermal optimization of the shape of the material is suggested.

Ti nanorod arrays with a medium density significantly promote osteogenesis and osteointegration

Science.gov (United States)

Ning, Chengyun; Wang, Shuangying; Zhu, Ye; Zhong, Meiling; Lin, Xi; Zhang, Yu; Tan, Guoxin; Li, Mei; Yin, Zhaoyi; Yu, Peng; Wang, Xiaolan; Li, Ying; He, Tianrui; Chen, Wei; Wang, Yingjun; Mao, Chuanbin

2016-01-01

Ti implants are good candidates in bone repair. However, how to promote bone formation on their surface and their consequent perfect integration with the surrounding tissue is still a challenge. To overcome such challenge, we propose to form Ti nanorods on their surface to promote the new bone formation around the implants. Here Ti nanorod arrays (TNrs) with different densities were produced on pure Ti surfaces using an anodizing method. The influence of TNr density on the protein adsorption as well as on the adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 pre-osteoblastic cells were assessed. The TNrs were also implanted into the bone defects in rabbits to test their application in promoting bone formation and osteointegration at the implant-bone interface. TNrs with the medium density were found to show the best capability in promoting the protein adsorption from surrounding medium, which in turn efficiently enhanced osteogenic differentiation in vitro and osteointegration in vivo. Our work suggests that growing TNrs with a medium density on the surface of traditional Ti implants is an efficient and facile method for promoting bone formation and osteointegration in bone repair.

Properties of medium-density fiberboard produced in an oil-heated laboratory press

Science.gov (United States)

O. Suchsland; G.E. Woodson

1976-01-01

Medium-density fiberboards from pressurized double-disk refined fibers have a close correlation between layer density and layer dynamic modulus of elasticity. Density distribution over the thickness was readily controlled by manipulating platen temperature and applied pressure. Thus, overall modulus of elasticity could be adjusted. In contrast to modulus of elasticity...

Differential growth responses to water balance of coexisting deciduous tree species are linked to wood density in a Bolivian tropical dry forest.

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Hooz A Mendivelso

Full Text Available A seasonal period of water deficit characterizes tropical dry forests (TDFs. There, sympatric tree species exhibit a diversity of growth rates, functional traits, and responses to drought, suggesting that each species may possess different strategies to grow under different conditions of water availability. The evaluation of the long-term growth responses to changes in the soil water balance should provide an understanding of how and when coexisting tree species respond to water deficit in TDFs. Furthermore, such differential growth responses may be linked to functional traits related to water storage and conductance. We used dendrochronology and climate data to retrospectively assess how the radial growth of seven coexisting deciduous tree species responded to the seasonal soil water balance in a Bolivian TDF. Linear mixed-effects models were used to quantify the relationships between basal area increment and seasonal water balance. We related these relationships with wood density and sapwood production to assess if they affect the growth responses to climate. The growth of all species responded positively to water balance during the wet season, but such responses differed among species as a function of their wood density. For instance, species with a strong growth response to water availability averaged a low wood density which may facilitate the storage of water in the stem. By contrast, species with very dense wood were those whose growth was less sensitive to water availability. Coexisting tree species thus show differential growth responses to changes in soil water balance during the wet season. Our findings also provide a link between wood density, a trait related to the ability of trees to store water in the stem, and wood formation in response to water availability.

Differential Growth Responses to Water Balance of Coexisting Deciduous Tree Species Are Linked to Wood Density in a Bolivian Tropical Dry Forest

Science.gov (United States)

Mendivelso, Hooz A.; Camarero, J. Julio; Royo Obregón, Oriol; Gutiérrez, Emilia; Toledo, Marisol

2013-01-01

A seasonal period of water deficit characterizes tropical dry forests (TDFs). There, sympatric tree species exhibit a diversity of growth rates, functional traits, and responses to drought, suggesting that each species may possess different strategies to grow under different conditions of water availability. The evaluation of the long-term growth responses to changes in the soil water balance should provide an understanding of how and when coexisting tree species respond to water deficit in TDFs. Furthermore, such differential growth responses may be linked to functional traits related to water storage and conductance. We used dendrochronology and climate data to retrospectively assess how the radial growth of seven coexisting deciduous tree species responded to the seasonal soil water balance in a Bolivian TDF. Linear mixed-effects models were used to quantify the relationships between basal area increment and seasonal water balance. We related these relationships with wood density and sapwood production to assess if they affect the growth responses to climate. The growth of all species responded positively to water balance during the wet season, but such responses differed among species as a function of their wood density. For instance, species with a strong growth response to water availability averaged a low wood density which may facilitate the storage of water in the stem. By contrast, species with very dense wood were those whose growth was less sensitive to water availability. Coexisting tree species thus show differential growth responses to changes in soil water balance during the wet season. Our findings also provide a link between wood density, a trait related to the ability of trees to store water in the stem, and wood formation in response to water availability. PMID:24116001

PHYSICAL-MECHANICAL CHARACTERISTICS OF CEMENT-BONDED KENAF BAST FIBRES COMPOSITE BOARDS WITH DIFFERENT DENSITIES

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B. AHMED AMEL

2017-08-01

Full Text Available This study was carried out to explore the potential of kenaf bast fibres (KBFs for production of cement-bonded kenaf composite boards (CBKCBs. More than 70% of the KBFs were of size >3.35 mm and length of 31±0.4 mm, therefore, they were used for CBKCBs production. The CBKCBs with the dimensions of 450 × 450 × 12 mm were produced using cement (C: KBF with proportion of (2:1 and different board densities (BD namely 1100, 1300 and 1500 kg/m3. The CBKCBs were first cured in a tank saturated with moisture for 7days, and then kept at room temperature for 21 days. Mechanical and physical properties of the CBKCBs were characterized with regards to their modulus of rupture (MOR, modulus of elasticity (MOE, internal bond (IB, water absorption (WA, and thickness swelling (TS. Results of the tested CBKCBs revealed that the MOR increased while the MOE decreased due to uniform distribution of KBFs. It was found that loading of KBFs has a negative influence on the internal bond (IB of the CBKCBs; the IB was reduced as KBFs tend to balling and making unmixed aggregates with the cement. These results showed that the CBKCB is a promising construction material that could potentially be used in different structural applications due to their good mechanical characteristics.

Implementation of new technologies in wood industry and their effect in wood products quality

OpenAIRE

ELVA ÇAUSHI; PANDELI MARKU

2014-01-01

There are about 300 companies producing furniture and about 250 small and medium enterprises (SME) producing sawn timber, which operate in the field of wood industry in Albania. This wood industry production is being challenged by the increasing demand in the domestic market, ranging from kitchen furniture to office and schools furniture, bedroom furniture, doors, windows, and saw timber in different dimensions. The production from the wood industry can fulfill about 80% of the domestic mark...

Bone cement allocation analysis in artificial cancellous bone structures

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Ivan Zderic

2017-01-01

Conclusion: The simulated leakage path seemed to be the most important adverse injection factor influencing the uniformity of cement distribution. Another adverse factor causing dispersion of this distribution was represented by the simulated bone marrow. However, the rather uniform distribution of the totally injected cement amount, considered as one unit, could be ascribed to the medium viscosity of the used cement. Finally, with its short waiting time of 45 s, the stepwise injection procedure was shown to be ineffective in preventing cement leakage.

The incorporation of low and medium level radioactive wastes (solids and liquids) in cement

International Nuclear Information System (INIS)

Brown, D.J.; Palmer, J.D.; Smith, D.L.

1983-10-01

The testing of cemented waste specimens containing sodium nitrate and sodium sulphate has been carried out over a period of two and a half years. One set of samples is kept under environmental conditions which simulate the anticipated storage conditions and a second series is stored under water. Additional results are reported here from the long-term stability testing of these simulated cemented wastes. Some applications of the method developed for measuring the apparent viscosity of cement pastes are described. Some preliminary information is given on the assessment of cement-waste mixing equipment. (U.K.)

Effect of endodontic cement on bone mineral density using serial dual-energy x-ray absorptiometry.

Science.gov (United States)

Saghiri, Mohammad Ali; Orangi, Jafar; Tanideh, Nader; Janghorban, Kamal; Sheibani, Nader

2014-05-01

Materials with new compositions were tested in order to develop dental materials with better properties. Calcium silicate-based cements, including white mineral trioxide aggregate (WMTA), may improve osteopromotion because of their composition. Nano-modified cements may help researchers produce ideal root-end filling materials. Serial dual-energy x-ray absorptiometry measurement was used to evaluate the effects of particle size and the addition of tricalcium aluminate (C3A) to a type of mineral trioxide aggregate-based cement on bone mineral density and the surrounding tissues in the mandible of rabbits. Forty mature male rabbits (N = 40) were anesthetized, and a bone defect measuring 7 × 1 × 1 mm was created on the semimandible. The rabbits were divided into 2 groups, which were subdivided into 5 subgroups with 4 animals each based on the defect filled by the following: Nano-WMTA (patent application #13/211.880), WMTA (as standard), WMTA without C3A, Nano-WMTA + 2% Nano-C3A (Fujindonjnan Industrial Co, Ltd, Fujindonjnan Xiamen, China), and a control group. Twenty and forty days postoperatively, the animals were sacrificed, and the semimandibles were removed for DXA measurement. The Kruskal-Wallis test followed by the Mann-Whitney U test showed significant differences between the groups at a significance level of P density at both intervals and P20 day = .004 and P40 day = .005 for bone mineral content. This study showed that bone regeneration was enhanced by reducing the particle size (nano-modified) and C3A mixture. This may relate to the existence of an external supply of minerals and a larger surface area of nano-modified material, which may lead to faster release rate of Ca(2+), inducing bone formation. Adding Nano-C3A to Nano-WMTA may improve bone regeneration properties. Copyright © 2014 American Association of Endodontists. All rights reserved.

Eucalyptus urophylla stands wood utilization at two different ages for production of particleboard panels

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Lourival Marin Mendes

2009-09-01

Full Text Available This work aimed to assess the quality of wood particle panels manufactured with wood from Eucalyptus urophylla stands at age 7 and at age 12 years. To that end, particleboard, oriented strand board (OSB and cement-bonded panels were produced in a laboratory and then analyzed for the following physical and mechanical properties: water absorption and thickness swell 2 and 24 hours after immersion, internal bond, compression parallel, as well as MOE and MOR from static bending. The obtained results demonstrate that tree age had little influence on the physical and mechanical properties of particleboard, OSB and cement-bonded panels. After evaluating the physical and mechanical properties of these three panel types, all manufactured with wood from Eucalyptus urophylla stands at age 7 and at age 12, we can argue that our results are satisfactory in comparison to existing literature results.

Ceramic microspheres for cementing applications

NARCIS (Netherlands)

2011-01-01

A method and apparatus for manufacturing ceramic microspheres from industrial slag. The microspheres have a particle size of about 38 microns to about 150 microns. The microspheres are used to create a cement slurry having a density of at least about 11 lbs/g. The resultant cement slurry may then be

Ceramic microspheres for cementing applications

NARCIS (Netherlands)

2010-01-01

A method and apparatus for manufacturing ceramic microspheres from industrial slag. The microspheres have a particle size of about 38 microns to about 150 microns. The microspheres are used to create a cement slurry having a density of at least about 11 lbs/g. The resultant cement slurry may then be

Ceramic microspheres for cementing applications

NARCIS (Netherlands)

2012-01-01

A method and apparatus for manufacturing ceramic microspheres from industrial slag. The microspheres have a particle size of about 38 microns to about 150 microns. The microspheres are used to create a cement slurry having a density of at least about 11 lbs/g. The resultant cement slurry may then be

Thermal Transmittance of Porous Hollow Clay Brick by Guarded Hot Box Method

Science.gov (United States)

Kim, Joonsoo

2018-03-01

The thermal property of a porous hollow clay brick was determined by measuring the thermal transmittance of the wall made of porous hollow clay bricks. Prior to the production of porous hollow clay bricks, nonporous and porous tiny clay bricks were prepared to determine the physico-mechanical properties by modifying the amount of wood flour and firing temperature. The bricks were produced by uniaxial pressing and then fired in an electric furnace. Their physico-mechanical properties were measured by water absorption, apparent porosity, bulk density, and compressive strength. The porous tiny clay bricks were produced with three types of wood flour: coarse wood flour (1-0.36 mm), medium-sized wood flour (0.36-0.15 mm), and fine wood flour (cement bricks. The two walls had a thermal transmittance of 1.42 and 2.72 W\\cdot m^{-2}\\cdot K^{-1}, respectively. The difference in thermal transmittance was due to the pores created with fine wood flour (< 0.08 mm) as a pore-forming agent.

Wood quality changes caused by mineral fertilization

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Carlos Roberto Sette Jr

2014-06-01

Full Text Available The diverse and important use of wood from fast growth eucalyptus plantations requires the analysis of the effect of mineral fertilizers on wood quality. The objective of this study was to evaluate the anatomical characteristics and wood density from Eucalyptus grandis trees (3 m x 2 m spacing fertilized with potassium and sodium (at planting, 6 th and 12th month. Fifteen (15 6 years old eucalyptus trees were selected (5 trees/treatment, cut and wood samples at DBH (1,3 m were taken for anatomical characteristics (fiber and vessels and wood density analysis. Results showed that eucalyptus trees treated with mineral fertilizers did not show significant alteration in average wood density, with radial profile model common to all three treatments, characterized by a values increase in the region next to the pith, toward to bark. Mineral fertilization influenced wood anatomical characteristics: treatment with sodium was characterized by thinner walls and lumen larger diameter; in treatment with potassium, larger vessels were detected.

Calorific value of Prosopis africana and Balanites aegyptiaca wood: Relationships with tree growth, wood density and rainfall gradients in the West African Sahel

Energy Technology Data Exchange (ETDEWEB)

Montes, Carmen Sotelo; Weber, John C. [World Agroforestry Centre (ICRAF), Sahel Office, B.P. E 5118 Bamako (Mali); Silva, Dimas Agostinho da; Bolzon de Muniz, Graciela Ines [Universidade Federal do Parana (UFPR), Av. Lothario Meissner, 900, CEP.: 80270-170-Curitiba (Brazil); Garcia, Rosilei A. [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Instituto de Florestas, Departamento de Produtos Florestais, BR 465, km 07, 23890-000, Seropedica, Rio de Janeiro (Brazil)

2011-01-15

Prosopis africana and Balanites aegyptiaca are native tree species in the West African Sahel and provide wood for fuel, construction and other essential products. A provenance/progeny test of each species was established at one relatively dry site in Niger, and evaluated at 13 years. Gross calorific value of the wood was determined for a random sample of trees in each test: gross CV and CVm{sup 3} = gross calorific value in MJ kg{sup -1} and MJ m{sup -3}, respectively. The major objectives were to determine if gross CV was positively correlated with wood density and tree growth, and if gross CV and/or CVm{sup 3} varied with rainfall gradients in the sample region. Provenances were grouped into a drier and more humid zone, and correlations were computed among all trees and separately in each zone. Results indicated that gross CV was not significantly correlated with density in either species. Gross CV was positively correlated with growth of P. africana (but not B. aegyptiaca) only in the drier zone. Gross CVm{sup 3} was positively correlated with growth of both species, and the correlations were stronger in the drier zone. Multiple regressions with provenance latitude, longitude and elevation indicated that provenance means for gross CV increased, in general, from the drier to the more humid zones. Regressions with gross CVm{sup 3} were not significant. Results are compared with earlier research reports from the provenance/progeny tests and with other tropical hardwood species; and practical implications are presented for tree improvement and conservation programs in the region. (author)

Study of glass alteration mechanisms in cement waters

International Nuclear Information System (INIS)

Depierre, S.

2012-01-01

In the French deep geological repository concept, intermediate-level vitrified waste packages could be disposed of concrete medium. Chemical composition and pH of the interstitial leaching water are expected to influence the chemical durability of glass. Investigations have thus been carried out to study glass dissolution mechanisms and kinetics in contact with cement waters. Three cement pore waters were studied: the first two correspond to two stages of the Portland cement aging and the third corresponds to equilibrium with a low pH concrete. The S/V ratio (glass-surface-area-to-solution-volume ratio) and the chemistry of cement waters are the two main parameters that control glass alteration mechanisms. If the leaching flow from the glass allows a degree of supersaturation to be reached and maintained which leads to nucleation of secondary phases, then precipitation of these phases drives glass dissolution. At a very low S/V ratio, the calcium uptake into the alteration layer increases its passivating properties. Conversely, at a high S/V ratio, the calcium precipitates as cementitious phases consuming elements which form the alteration layer. The glass dissolution is maintained at a high rate. This study contributes to highlighting the beneficial role of low pH cement in glass alteration, and is a first step towards understanding the mechanisms between the glass and the cement medium. (author) [fr

Microstructural analysis of geopolymer developed from wood fly ash, post-mortem doloma refractory and metakaolin

International Nuclear Information System (INIS)

Moura, Jailes de Santana; Mafra, Marcio Paulo de Araujo; Rabelo, Adriano Alves; Fagury, Renata Lilian Ribeiro Portugal; Fagury Neto, Elias

2016-01-01

Geopolymers are one of the widely discussed topics of materials science in recent times due to its vast potential as an alternative binder material to cement. This work aimed to evaluate the microstructure of geopolymers developed from wood fly ash, post-mortem doloma refractory and metakaolin. A preliminary study has been completed and achieved significant results compressive strength: the best formulation of geopolymer paste obtained approximately 25 MPa. Microstructural analysis by scanning electron microscopy, the geopolymer paste, allowed to verify the homogeneity, distribution of components, and providing evidence of raw materials that do not respond if there was crystalline phase, porosity and density of the structure. (author)

Potential of Using Recycled Low-Density Polyethylene in Wood Composites Board

Directory of Open Access Journals (Sweden)

A. C. Igboanugo

2011-03-01

Full Text Available The aim of this study was to investigate the suitability of using recycled low density polyethylene (RLDPE in wood board manufacturing. The composite board was produced by compressive moulding by increasing the percentage LDPE from 30 to 50wt% with interval of 10wt% at a temperatures of 140 and 180oC, pressure of 30-40 Kg/cm2 and pressing time 7-13minutes. The microstructure and mechanical properties: modulus of rupture (MOR, modulus of elasticity (MOE, Tensile strength, impact strength properties of boards were determined. The results showed that high modulus of rupture of 20.31N/mm2and MOE of 1363N/mm2 were obtained from board produced at 140oC, 60/40wt% wood particles/LDPE content. The uniform distribution of the particles and the recycled LDPE in the microstructure of the composites board is the major factor responsible for the improvement in the mechanical properties. The results showed that the MOE, MOR meets the minimum requirements of the European standards, for general purpose. The boards produced had tensile strength that is within the requirement. Hence this LDPE can be used in board production for general purpose applications.

SO2 Release as a Consequence of Alternative Fuel Combustion in Cement Rotary Kiln Inlets

DEFF Research Database (Denmark)

Cortada Mut, Maria del Mar; Nørskov, Linda Kaare; Glarborg, Peter

2015-01-01

The combustion of alternative fuels in direct contact with the bed material of the rotary kiln may cause local reducing conditions and, subsequently, decomposition of sulfates from cement raw materials, increasing the SO2 concentration in the gas phase. The decomposition of sulfates increases...... the sulfur circulation and may be problematic because high sulfur circulation can cause sticky material buildup, affecting the process operation of the cement kiln system. The SO2 release from cement raw materials during combustion of pine wood and tire rubber has been studied experimentally in a high...

Use of petroleum code as fuel in the cement industry

International Nuclear Information System (INIS)

Nawaz, S.

2006-01-01

The Cement industry is a very energy intensive industry. Each ton of cement produced requires 60 to 130 kilograms of fuel oil or an equivalent fuelling amount also requires an average 110 kWh of electricity as well over 40% of total production cost is the energy requirements in the cement industry (i.2). Normally oil, gas or coal is fired in cement kilns as traditional fuels. However use of waste, both as alternative fuels and raw materials is now common practice in many cement companies. Many different types of wastes are burnt today in cement kilns like used tyres, rubber, paper waste, waste oils, waste wood, paper sludge, sewage, animal meal and animal remains (i,4). The choice of fuel for the purpose is normally based on price and availability considering different properties of the fuel as energy contents, ash contents, moisture and volatiles contents. Petcoke is not yet produced in any petroleum refinery in Pakistan but it is abundantly available in the market worldwide as it is obtained as a waste product during the refining processes. The purpose of the current research is to figure out the suitability of petroleum coke as a fuel for cement industry both on technical and economic basis. (author)

Mechanical Properties of Medium Density Fibreboard Composites Material Using Recycled Rubber and Coconut Coir

OpenAIRE

S. Mahzan; A.M. Ahmad Zaidi; M.I. Ghazali; N. Arsat; M.N. M. Hatta

2010-01-01

Natural fibre reinforced composite has emerged as highly potential replacement for synthetic fibres. Various natural waste fibres have been adopted for various engineering applications. This paper investigates the mechanical properties of medium density fibreboard composites material fabricated using recycled rubber and coconut coir. The suitability of using recycled rubber and coconut coir as a raw material and polyurethane as a resin in the manufacturer of medium density fibreboard was also...

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

Science.gov (United States)

Chen, Irvin Allen

-belite cement that contained medium C4A3 S¯ and C2S contents showed good dimensional stability, sulfate resistance, and compressive strength development and was considered the optimum phase composition for calcium sulfoaluminate-belite cement in terms of comparable performance characteristics to portland cement. Furthermore, two calcium sulfoaluminate-belite cement clinkers were successfully synthesized from natural and waste materials such as limestone, bauxite, flue gas desulfurization sludge, Class C fly ash, and fluidized bed ash proportioned to the optimum calcium sulfoaluminate-belite cement synthesized from reagent-grade chemicals. Waste materials composed 30% and 41% of the raw ingredients. The two calcium sulfoaluminate-belite cements synthesized from natural and waste materials showed good dimensional stability, sulfate resistance, and compressive strength development, comparable to commercial portland cement.

Compressive Strength and Physical Properties Behavior of Cement Mortars with addition of Cement Klin Dust

Directory of Open Access Journals (Sweden)

Auday A Mehatlaf

2017-12-01

Full Text Available Cement Klin Dust (CKD was the waste of almost cement industry factories, so that in this paper utilization of CKD as filler in cement and/or concrete was the main objective. CKD from the Karbala cement factory had been used and analysis to know the chemical composition of the oxides was done. In this paper cement mortars with different weight percentages of CKD (0,5,10,20,30,40 had been prepared. Physical properties such as density and porosity were done in different age curing (3, 7, 28 day. In addition, mechanical properties included the coefficient of thermal conductivity and compressive strength had also observed with different age (3,7, and 28 for all prepared specimens. From the obtained the experimental results and their discussion, it was clear that the addition (20% of CKD had the good results in cement mortars.  

Energy release rate analysis on the interface cracks of enamel-cement-bracket fracture using virtual crack closure technique

Science.gov (United States)

Samshuri, S. F.; Daud, R.; Rojan, M. A.; Mat, F.; Basaruddin, K. S.; Hassan, R.

2017-10-01

This paper presents the energy method to evaluate fracture behavior of enamel-cement-bracket system based on cement thickness. Finite element (FE) model of enamel-cement-bracket was constructed by using ANSYS Parametric Design Language (APDL). Three different thickness were used in this study, 0.05, 0.2, and 0.271 mm which assigned as thin, medium and thick for both enamel-cement and cement bracket interface cracks. Virtual crack closure technique (VCCT) was implemented as a simulation method to calculated energy release rate (ERR). Simulation results were obtained for each thickness are discussed by using Griffith’s energy balance approach. ERR for thin thickness are found to be the lowest compared to medium and thick. Peak value of ERR also showed a significant different between medium and thick thickness. Therefore, weakest bonding occurred at low cement thickness because less load required to produce enough energy to detach the bracket. For medium and thick thickness, both increased rapidly in energy value at about the mid-point of the enamel-cement interface. This behavior occurred because of the increasing in mechanical and surface energy when the cracks are increasing. However, result for thick thickness are higher at mid-point compared to thin thickness. In conclusion, fracture behavior of enamel cracking process for medium most likely the safest to avoid enamel fracture and withstand bracket debonding.

Temporal Variation of Wood Density and Carbon in Two Elevational Sites of Pinus cooperi in Relation to Climate Response in Northern Mexico

Science.gov (United States)

Pompa-García, Marín; Venegas-González, Alejandro

2016-01-01

Forest ecosystems play an important role in the global carbon cycle. Therefore, understanding the dynamics of carbon uptake in forest ecosystems is much needed. Pinus cooperi is a widely distributed species in the Sierra Madre Occidental in northern Mexico and future climatic variations could impact these ecosystems. Here, we analyze the variations of trunk carbon in two populations of P. cooperi situated at different elevational gradients, combining dendrochronological techniques and allometry. Carbon sequestration (50% biomass) was estimated from a specific allometric equation for this species based on: (i) variation of intra-annual wood density and (ii) diameter reconstruction. The results show that the population at a higher elevation had greater wood density, basal area, and hence, carbon accumulation. This finding can be explained by an ecological response of trees to adverse weather conditions, which would cause a change in the cellular structure affecting the within-ring wood density profile. The influence of variations in climate on the maximum density of chronologies showed a positive correlation with precipitation and the Multivariate El Niño Southern Oscillation Index during the winter season, and a negative correlation with maximum temperature during the spring season. Monitoring previous conditions to growth is crucial due to the increased vulnerability to extreme climatic variations on higher elevational sites. We concluded that temporal variability of wood density contributes to a better understanding of environmental historical changes and forest carbon dynamics in Northern Mexico, representing a significant improvement over previous studies on carbon sequestration. Assuming a uniform density according to tree age is incorrect, so this method can be used for environmental mitigation strategies, such as for managing P. cooperi, a dominant species of great ecological amplitude and widely used in forest industries. PMID:27272519

Temporal Variation of Wood Density and Carbon in Two Elevational Sites of Pinus cooperi in Relation to Climate Response in Northern Mexico.

Directory of Open Access Journals (Sweden)

Marín Pompa-García

Full Text Available Forest ecosystems play an important role in the global carbon cycle. Therefore, understanding the dynamics of carbon uptake in forest ecosystems is much needed. Pinus cooperi is a widely distributed species in the Sierra Madre Occidental in northern Mexico and future climatic variations could impact these ecosystems. Here, we analyze the variations of trunk carbon in two populations of P. cooperi situated at different elevational gradients, combining dendrochronological techniques and allometry. Carbon sequestration (50% biomass was estimated from a specific allometric equation for this species based on: (i variation of intra-annual wood density and (ii diameter reconstruction. The results show that the population at a higher elevation had greater wood density, basal area, and hence, carbon accumulation. This finding can be explained by an ecological response of trees to adverse weather conditions, which would cause a change in the cellular structure affecting the within-ring wood density profile. The influence of variations in climate on the maximum density of chronologies showed a positive correlation with precipitation and the Multivariate El Niño Southern Oscillation Index during the winter season, and a negative correlation with maximum temperature during the spring season. Monitoring previous conditions to growth is crucial due to the increased vulnerability to extreme climatic variations on higher elevational sites. We concluded that temporal variability of wood density contributes to a better understanding of environmental historical changes and forest carbon dynamics in Northern Mexico, representing a significant improvement over previous studies on carbon sequestration. Assuming a uniform density according to tree age is incorrect, so this method can be used for environmental mitigation strategies, such as for managing P. cooperi, a dominant species of great ecological amplitude and widely used in forest industries.

Preparation, physical-chemical characterisation and cytocompatibility of calcium carbonate cements

OpenAIRE

Combes, Christèle; Miao, Baoji; Bareille, Reine; Rey, Christian

2006-01-01

The feasibility of calcium carbonate cements involving the recrystallisation of metastable calcium carbonate varieties has been demonstrated. Calcium carbonate cement compositions presented in this paper can be prepared straightforwardly by simply mixing water (liquid phase) with two calcium carbonate phases (solid phase) which can be easily obtained by precipitation. An original cement composition was obtained by mixing amorphous calcium carbonate and vaterite with an aqueous medium. The cem...

Black locus (Robinia pseudoacacia L.) and Honey locust (Gleditsia triacanthos L.): technological aspects in relation with the use in solid wood products; Acaia blanca (Robinia pseudoacacia L.) y acacia negra (Gleditsia triacanthos L.): aspectos tecnologicos y relacionados al empleo en productos de madera maciza

Energy Technology Data Exchange (ETDEWEB)

Keil, G.; Spavento, E.; Murace, M.; Millanes, A.

2011-07-01

Robinia pseudoacacia L. and Gleditsia triacanthos L, are tree species from USA and both was introduced in Europe. In the province of Buenos Aires, Argentina, plantations of these species are scattered, whose wood hasn't been characterized technologically by standardized tests. The objective of this job was to characterize technologically Black locus and Honey locust woods, both implanted in the province of Buenos Aires for its inclusion in the timber market. The physical and mechanical properties determined were: content humidity, apparent densities, dimensional changes, Janka hardness, static bending, cut parallel to fibers,compression perpendicular and parallel to fibers. Natural durability was estimated. Black locus and Honey locust woods were medium density and medium stability, hard, resistant to the cut and the compression perpendicular to fibers and showed values medium to low in parameters of static bending and compression parallel to fibers, values to take into account when designing structural elements. Black locus was the most resistant to fungal degradation. Both woods can be considered suitable for high-value uses in the construction and furniture industries (interior and exterior). (Author) 29 refs.

Primary stability and self-tapping blades: biomechanical assessment of dental implants in medium-density bone.

Science.gov (United States)

Kim, Yung-Soo; Lim, Young-Jun

2011-10-01

The aim of this biomechanical study was to assess the influence of self-tapping blades in terms of primary implant stability between implants with self-tapping blades and implants without self-tapping blades using five different analytic methods, especially in medium-density bone. Two different types of dental implants (4 × 10 mm) were tested: self-tapping and non-self-tapping. The fixture design including thread profiles was exactly the same between the two groups; the only difference was the presence of cutting blades on one half of the apical portion of the implant body. Solid rigid polyurethane blocks with corresponding densities were selected to simulate medium-density bone. Five mechanical assessments (insertion torque, resonance frequency analysis [RFA], reverse torque, pull-out and push in test) were performed for primary stability. Implants without self-tapping blades showed significantly higher values (P0.05). The outcomes of the present study indicate that the implant body design without self-tapping blades has a good primary stability compared with that with self-tapping blades in medium-density bone. Considering the RFA, a distinct layer of cortical bone on marginal bone will yield implant stability quotient values similar to those in medium-bone density when implants have the same diameter. © 2011 John Wiley & Sons A/S.

Use of wood ash for road stabilisation

International Nuclear Information System (INIS)

Lagerkvist, A.; Lind, B.

2009-01-01

Due to warmer winters in Sweden, the bearing capacity of forestry roads has become increasingly problematic in recent years. Road stabilization is needed in order to get timber out from the forests. This usually involves the addition of cement to the road body. However, wood ash is a possible substitute for cement because it has similar properties. Using wood ash has the added advantage of saving landfill space. This paper presented an ongoing laboratory study on leaching and mechanical stability, as well as frost-sensitivity using a 30 per cent ash addition to natural soils for reinforcing a forestry road near Timra in central Sweden. The road was being monitored with regard to environmental impact and mechanical properties. The paper discussed the potential of biofuel ashes and the increasing need to reinforce infrastructure due to climate change. The environmental impact from ash use in road constructions was then addressed. It was concluded that the application of ash in road construction would help to strengthen forest roads, make them more resistant to climatic change and render them accessible year-round. 32 refs., 3 tabs., 2 figs.

Preparation, physical-chemical characterisation and cytocompatibility of calcium carbonate cements.

Science.gov (United States)

Combes, C; Miao, Baoji; Bareille, Reine; Rey, Christian

2006-03-01

The feasibility of calcium carbonate cements involving the recrystallisation of metastable calcium carbonate varieties has been demonstrated. Calcium carbonate cement compositions presented in this paper can be prepared straightforwardly by simply mixing water (liquid phase) with two calcium carbonate phases (solid phase) which can be easily obtained by precipitation. An original cement composition was obtained by mixing amorphous calcium carbonate and vaterite with an aqueous medium. The cement set and hardened within 2h at 37 degrees C in an atmosphere saturated with water and the final composition of the cement consisted mostly of aragonite. The hardened cement was microporous and showed poor mechanical properties. Cytotoxicity tests revealed excellent cytocompatibility of calcium carbonate cement compositions. Calcium carbonates with a higher solubility than the apatite formed for most of the marketed calcium phosphate cements might be of interest to increase biomedical cement resorption rates and to favour its replacement by bone tissue.

ULTRA-LIGHTWEIGHT CEMENT

Energy Technology Data Exchange (ETDEWEB)

Fred Sabins

2001-10-23

The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). Work reported herein addresses tasks performed in the fourth quarter as well as the other three quarters of the past year. The subjects that were covered in previous reports and that are also discussed in this report include: Analysis of field laboratory data of active cement applications from three oil-well service companies; 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; and Comparison of compressive strengths of ULHS systems using ultrasonic and crush methods Results reported from the fourth quarter include laboratory testing of ULHS systems along with other lightweight cement systems--foamed and sodium silicate slurries. These comparison studies were completed for two different densities (10.0 and 11.5 lb/gal) and three different field application scenarios. Additional testing included the mechanical properties of ULHS systems and other lightweight systems. Studies were also performed to examine the effect that circulation by centrifugal pump during mixing has on breakage of ULHS.

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)

Energy wood. Part 2b: Wood pellets and pellet space-heating systems

International Nuclear Information System (INIS)

Nussbaumer, T.

2002-01-01

The paper gives an overview on pellet utilization including all relevant process steps: Potential and properties of saw dust as raw material, pellet production with drying and pelletizing, standardization of wood pellets, storage and handling of pellets, combustion of wood pellets in stoves and boilers and applications for residential heating. In comparison to other wood fuels, wood pellets show several advantages: Low water content and high heating value, high energy density, and homogeneous properties thus enabling stationary combustion conditions. However, quality control is needed to ensure constant properties of the pellets and to avoid the utilization of contaminated raw materials for the pellet production. Typical data of efficiencies and emissions of pellet stoves and boilers are given and a life cycle analysis (LCA) of wood pellets in comparison to log wood and wood chips is described. The LCA shows that wood pellets are advantageous thanks to relatively low emissions. Hence, the utilization of wood pellet is proposed as a complementary technology to the combustion of wood chips and log wood. Finally, typical fuel cost of wood pellets in Switzerland are given and compared with light fuel oil. (author)

Surface characterization of weathered wood-plastic composites produced from modified wood flour

Science.gov (United States)

James S. Fabiyi; Armando G. McDonald; Nicole M. Stark

2007-01-01

The effects of weathering on the surface properties of wood-plastic composites (WPC) were examined. High-density polyethylene (HDPE) based WPCs made from modified wood flour (untreated, extractives free, and holocellulose (delignified) fibers) were subjected to accelerated (xenon-arc) weathering. Colorimetry and Fourier-transform infrared spectroscopy were employed to...

Specific features of electrical properties of porous biocarbons prepared from beech wood and wood artificial fiberboards

Science.gov (United States)

Popov, V. V.; Orlova, T. S.; Magarino, E. Enrique; Bautista, M. A.; Martínez-Fernández, J.

2011-02-01

This paper reports on comparative investigations of the structural and electrical properties of biomorphic carbons prepared from natural beech wood, as well as medium-density and high-density fiberboards, by means of carbonization at different temperatures T carb in the range 650-1000°C. It has been demonstrated using X-ray diffraction analysis that biocarbons prepared from medium-density and high-density fiberboards at all temperatures T carb contain a nanocrystalline graphite component, namely, three-dimensional crystallites 11-14 Å in size. An increase in the carbonization temperature T carb to 1000°C leads to the appearance of a noticeable fraction of two-dimensional graphene particles with the same sizes. The temperature dependences of the electrical resistivity ρ of the biomorphic carbons have been measured and analyzed in the temperature range 1.8-300 K. For all types of carbons under investigation, an increase in the carbonization temperature T carb from 600 to 900°C leads to a change in the electrical resistivity at T = 300 K by five or six orders of magnitude. The dependences ρ( T) for these materials are adequately described by the Mott law for the variable-range hopping conduction. It has been revealed that the temperature dependence of the electrical resistivity exhibits a hysteresis, which has been attributed to thermomechanical stresses in an inhomogeneous structure of the biocarbon prepared at a low carbonization temperature T carb. The crossover to the conductivity characteristic of disordered metal systems is observed at T carb ≳ 1000°C.

Influence of lactose addition to gentamicin-loaded acrylic bone cement on the kinetics of release of the antibiotic and the cement properties.

Science.gov (United States)

Frutos, Gloria; Pastor, José Ygnacio; Martínez, Noelia; Virto, María Rosa; Torrado, Susana

2010-03-01

The purpose of this study was to characterize a poly(methyl methacrylate) bone cement that was loaded with the antibiotic gentamicin sulphate (GS) and lactose, which served to modulate the release of GS from cement specimens. The release of GS when the cement specimens were immersed in phosphate-buffered saline at 37 degrees Celsius was determined spectrophotometrically. The microstructure, porosity, density, tensile properties and flexural properties of the cements were determined before and after release of GS. A kinetics model of the release of GS from the cement that involved a coupled mechanism based on dissolution/diffusion processes and an initial burst effect was proposed. Dissolution assay results showed that drug elution was controlled by a diffusion mechanism which can be modulated by lactose addition. Density values and mechanical properties (tensile strength, flexural strength, elastic modulus and fracture toughness) were reduced by the increased porosity resulting from lactose addition, but maintained acceptable values for the structural functions of bone cement. The present results suggest that lactose-modified, gentamicin-loaded acrylic bone cements are potential candidates for use in various orthopaedic and dental applications. Copyright 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

QUALITY OF REACTION WOOD IN EucalyptusTREES TILTED BY WIND FOR PULP PRODUCTION

Directory of Open Access Journals (Sweden)

Walter Torezani Neto Boschetti

2017-09-01

Full Text Available This study aims to evaluate the quality of normal, tension and opposite wood of eucalyptus trees lengthwise, in straight and inclined stems, affected by wind action. It also aims to explain the pulping parameters resultant from the quality of the wood. The trees were grouped into four tilt ranges, ranging from 0 to 50º, and the basic density, chemical composition of the wood, and performance in kraft pulping were assessed. Normal and tension wood had similar basic densities; while for opposite wood, the density was lower, being responsible for a decrease in reaction wood density. The chemical composition of the wood was influenced by the presence of reaction wood in the stem.Tension and opposite wood showed lower levels of extractives and lignin and higher holocellulose content when compared to normal wood, with favorable wood quality for pulping. The increase in holocellulose content and the reduction of lignin and extractives content contributed positively to a more delignified pulp and reduction of the Kappa number. However, after cooking the reaction wood under the same conditions as those of normal wood, reaction wood pulping tends to have a lower screen yields. Due to differences in basic density and chemical constituents between opposite and normal wood, it is recommended not to designate the opposite wood as normal wood.

Patterns in hydraulic architecture from roots to branches in six tropical tree species from cacao agroforestry and their relation to wood density and stem growth

Directory of Open Access Journals (Sweden)

Martyna Malgorzata Kotowska

2015-03-01

Full Text Available For decades it has been assumed that the largest vessels are generally found in roots and that vessel size and corresponding sapwood area-specific hydraulic conductivity are acropetally decreasing towards the distal twigs. However, recent studies from the perhumid tropics revealed a hump-shaped vessel size distribution. Worldwide tropical perhumid forests are extensively replaced by agroforestry systems often using introduced species of various biogeographical and climatic origins. Nonetheless, it is unknown so far what kind of hydraulic architectural patterns are developed in those agroforestry tree species and which impact this exerts regarding important tree functional traits, such as stem growth, hydraulic efficiency and wood density. We investigated wood anatomical and hydraulic properties of the root, stem and branch wood in Theobroma cacao and five common shade tree species in agroforestry systems on Sulawesi (Indonesia; three of these were strictly perhumid tree species, and the other three tree species are tolerating seasonal drought. The overall goal of our study was to relate these properties to stem growth and other tree functional traits such as foliar nitrogen content and sapwood to leaf area ratio. Our results confirmed a hump-shaped vessel size distribution in nearly all species. Drought-adapted species showed divergent patterns of hydraulic conductivity, vessel density and relative vessel lumen area between root, stem and branch wood compared to wet forest species. Confirming findings from natural old-growth forests in the same region, wood density showed no relationship to specific conductivity. Overall, aboveground growth performance was better predicted by specific hydraulic conductivity than by foliar traits and wood density. Our study results suggest that future research on conceptual trade-offs of tree hydraulic architecture should consider biogeographical patterns underlining the importance of anatomical adaptation

Effects of Recent Minimum Temperature and Water Deficit Increases on Pinus pinaster Radial Growth and Wood Density in Southern Portugal.

Science.gov (United States)

Kurz-Besson, Cathy B; Lousada, José L; Gaspar, Maria J; Correia, Isabel E; David, Teresa S; Soares, Pedro M M; Cardoso, Rita M; Russo, Ana; Varino, Filipa; Mériaux, Catherine; Trigo, Ricardo M; Gouveia, Célia M

2016-01-01

Western Iberia has recently shown increasing frequency of drought conditions coupled with heatwave events, leading to exacerbated limiting climatic conditions for plant growth. It is not clear to what extent wood growth and density of agroforestry species have suffered from such changes or recent extreme climate events. To address this question, tree-ring width and density chronologies were built for a Pinus pinaster stand in southern Portugal and correlated with climate variables, including the minimum, mean and maximum temperatures and the number of cold days. Monthly and maximum daily precipitations were also analyzed as well as dry spells. The drought effect was assessed using the standardized precipitation-evapotranspiration (SPEI) multi-scalar drought index, between 1 to 24-months. The climate-growth/density relationships were evaluated for the period 1958-2011. We show that both wood radial growth and density highly benefit from the strong decay of cold days and the increase of minimum temperature. Yet the benefits are hindered by long-term water deficit, which results in different levels of impact on wood radial growth and density. Despite of the intensification of long-term water deficit, tree-ring width appears to benefit from the minimum temperature increase, whereas the effects of long-term droughts significantly prevail on tree-ring density. Our results further highlight the dependency of the species on deep water sources after the juvenile stage. The impact of climate changes on long-term droughts and their repercussion on the shallow groundwater table and P. pinaster's vulnerability are also discussed. This work provides relevant information for forest management in the semi-arid area of the Alentejo region of Portugal. It should ease the elaboration of mitigation strategies to assure P. pinaster's production capacity and quality in response to more arid conditions in the near future in the region.

Effects of Recent Minimum Temperature and Water Deficit Increases on Pinus pinaster Radial Growth and Wood Density in Southern Portugal

Science.gov (United States)

Kurz-Besson, Cathy B.; Lousada, José L.; Gaspar, Maria J.; Correia, Isabel E.; David, Teresa S.; Soares, Pedro M. M.; Cardoso, Rita M.; Russo, Ana; Varino, Filipa; Mériaux, Catherine; Trigo, Ricardo M.; Gouveia, Célia M.

2016-01-01

Western Iberia has recently shown increasing frequency of drought conditions coupled with heatwave events, leading to exacerbated limiting climatic conditions for plant growth. It is not clear to what extent wood growth and density of agroforestry species have suffered from such changes or recent extreme climate events. To address this question, tree-ring width and density chronologies were built for a Pinus pinaster stand in southern Portugal and correlated with climate variables, including the minimum, mean and maximum temperatures and the number of cold days. Monthly and maximum daily precipitations were also analyzed as well as dry spells. The drought effect was assessed using the standardized precipitation-evapotranspiration (SPEI) multi-scalar drought index, between 1 to 24-months. The climate-growth/density relationships were evaluated for the period 1958-2011. We show that both wood radial growth and density highly benefit from the strong decay of cold days and the increase of minimum temperature. Yet the benefits are hindered by long-term water deficit, which results in different levels of impact on wood radial growth and density. Despite of the intensification of long-term water deficit, tree-ring width appears to benefit from the minimum temperature increase, whereas the effects of long-term droughts significantly prevail on tree-ring density. Our results further highlight the dependency of the species on deep water sources after the juvenile stage. The impact of climate changes on long-term droughts and their repercussion on the shallow groundwater table and P. pinaster’s vulnerability are also discussed. This work provides relevant information for forest management in the semi-arid area of the Alentejo region of Portugal. It should ease the elaboration of mitigation strategies to assure P. pinaster’s production capacity and quality in response to more arid conditions in the near future in the region. PMID:27570527

Nanofunctionalized zirconia and barium sulfate particles as bone cement additives

Directory of Open Access Journals (Sweden)

Riaz Gillani

2009-12-01

Full Text Available Riaz Gillani1, Batur Ercan1, Alex Qiao3, Thomas J Webster1,21Division of Engineering, 2Department of Orthopaedics, Brown University, Providence, RI, USA; 3G3 Technology Innovations, LLC, Pittsford, NY, USAAbstract: Zirconia (ZrO2 and barium sulfate (BaSO4 particles were introduced into a methyl methacrylate monomer (MMA solution with polymethyl methacrylate (PMMA beads during polymerization to develop the following novel bone cements: bone cements with unfunctionalized ZrO2 micron particles, bone cements with unfunctionalized ZrO2 nanoparticles, bone cements with ZrO2 nanoparticles functionalized with 3-(trimethoxysilylpropyl methacrylate (TMS, bone cements with unfunctionalized BaSO4 micron particles, bone cements with unfunctionalized BaSO4 nanoparticles, and bone cements with BaSO4 nanoparticles functionalized with TMS. Results demonstrated that in vitro osteoblast (bone-forming cell densities were greater on bone cements containing BaSO4 ceramic particles after four hours compared to control unmodified bone cements. Osteoblast densities were also greater on bone cements containing all of the ceramic particles after 24 hours compared to unmodified bone cements, particularly those bone cements containing nanofunctionalized ceramic particles. Bone cements containing ceramic particles demonstrated significantly altered mechanical properties; specifically, under tensile loading, plain bone cements and bone cements containing unfunctionalized ceramic particles exhibited brittle failure modes whereas bone cements containing nanofunctionalized ceramic particles exhibited plastic failure modes. Finally, all bone cements containing ceramic particles possessed greater radio-opacity than unmodified bone cements. In summary, the results of this study demonstrated a positive impact on the properties of traditional bone cements for orthopedic applications with the addition of unfunctionalized and TMS functionalized ceramic nanoparticles

Dynamic determination of modulus of elasticity of full-size wood composite panels using a vibration method

Science.gov (United States)

Cheng Guan; Houjiang Zhang; Lujing Zhou; Xiping Wang

2015-01-01

A vibration testing method based on free vibration theory in a ‘‘free–free” support condition was investigated for evaluating the modulus of elasticity (MOE) of full-size wood composite panels (WCPs). Vibration experiments were conducted on three types of WCPs (medium density fibreboard, particleboard, and plywood) to determine the dynamic MOE of the panels. Static...

Influence of various amount of diatomaceous earth used as cement substitute on mechanical properties of cement paste

Science.gov (United States)

Pokorný, Jaroslav; Pavlíková, Milena; Medved, Igor; Pavlík, Zbyšek; Zahálková, Jana; Rovnaníková, Pavla; Černý, Robert

2016-06-01

Active silica containing materials in the sub-micrometer size range are commonly used for modification of strength parameters and durability of cement based composites. In addition, these materials also assist to accelerate cement hydration. In this paper, two types of diatomaceous earths are used as partial cement replacement in composition of cement paste mixtures. For raw binders, basic physical and chemical properties are studied. The chemical composition of tested materials is determined using classical chemical analysis combined with XRD method that allowed assessment of SiO2 amorphous phase content. For all tested mixtures, initial and final setting times are measured. Basic physical and mechanical properties are measured on hardened paste samples cured 28 days in water. Here, bulk density, matrix density, total open porosity, compressive and flexural strength, are measured. Relationship between compressive strength and total open porosity is studied using several empirical models. The obtained results give evidence of high pozzolanic activity of tested diatomite earths. Their application leads to the increase of both initial and final setting times, decrease of compressive strength, and increase of flexural strength.

CEMENT KILN DUST AS A MATERIAL FOR BUILDING BLOCKS ...

African Journals Online (AJOL)

This paper presents the results of a study on the properties of hollow sandcrete blocks with cement kiln dust (CKD) as an additive and as a replacement for ordinary portland cement (OPC). When CKD was used as a replacement for cement, the compressive strength and density of blocks generally decreased with higher ...

Applications of radioactive methods in cement concrete testing

International Nuclear Information System (INIS)

Dinakaran, M.; Vijayaraghavan, S.R.

1979-01-01

Basic principles regarding the neutron moderation technique and the successful application of this technique for determining the moisture and cement content in hardened concrete are briefly discussed. Since fast neutrons are converted into slow thermal neutrons by elastic scattering in the presence of hydrogen nuclei, it is possible to determine the moisture content in hardened cement concrete using precalibrated relationships. Also since most of the hydrogenous matter in concrete pertains to non-fixed water and hydrated cement compounds, an analysis of slow neutron counts on a sample at different non-fixed moisture contents make the estimation of cement content possible using the mathematical relationship between cement content, degree of hydration and the equivalent moisture content. The method developed is quick, non-destructive, and repeatable at the same time giving better accuracy when compared to conventional chemical methods. Use was also made of gamma ray transmission method for determining the differential density at various depths in a cement concrete pavement making use of cores cut from the pavement. Further, development proposed for determination of density at different depths of pavement in situ is also discussed. (auth.)

Nanoscaled Mechanical Properties of Cement Composites Reinforced with Carbon Nanofibers

OpenAIRE

Barbhuiya, Salim; Chow, PengLoy

2017-01-01

This paper reports the effects of carbon nanofibers (CNFs) on nanoscaled mechanical properties of cement composites. CNFs were added to cement composites at the filler loading of 0.2 wt % (by wt. of cement). Micrographs based on scanning electron microscopy (SEM) show that CNFs are capable of forming strong interfacial bonding with cement matrices. Experimental results using nanoindentation reveal that the addition of CNFs in cement composites increases the proportions of high-density calcium...

A synthesis of research on wood products and greenhouse gas impacts

International Nuclear Information System (INIS)

Sathre, R.; O'Connor, J.

2008-11-01

Existing scientific literature on the wood products industry was reviewed in an effort to summarize consensus findings, or range of findings, addressing the net life cycle greenhouse gas footprint of wood construction products. The report sought to clarify whether actively managing forests for wood production was better, worse or neutral for climate change than leaving the forest in its natural state. In addition, it sought to quantify the greenhouse gas emissions avoided per unit of wood substituted for non-wood materials. Forty-eight international studies were examined in terms of fossil energy used in wood manufacturing and compared alternatives, such as the avoidance of industrial process carbon emissions as with cement manufacturing; the storage of carbon in forests and forest products; the use of wood by-products as a biofuel replacement for fossil fuels; and carbon storage and emission due to forest products in landfills. The report presented a list of studies reviewed and individual summaries of study findings. A meta-analysis of displacement factors of wood product use was also presented. It was concluded from all of the studies reviewed, that the production of wood-based materials and products results in less greenhouse gas emission than the production of functionally comparable non-wood materials and products. 48 refs., 1 tab.

A comprehensive model to describe radiolytic processes in cement medium

DEFF Research Database (Denmark)

Bouniol, P.; Bjergbakke, Erling

2008-01-01

Basic mechanisms controlling the radiolysis in cementitious matrices are reviewed in the specific context of the gamma irradiation, in closed system without upper vapour space, at 25 degrees C, with a pore solution representative of a Portland cement paste. A general survey of data corresponding...

Cement As a Waste Form for Nuclear Fission Products: The Case of (90)Sr and Its Daughters.

Science.gov (United States)

Dezerald, Lucile; Kohanoff, Jorge J; Correa, Alfredo A; Caro, Alfredo; Pellenq, Roland J-M; Ulm, Franz J; Saúl, Andrés

2015-11-17

One of the main challenges faced by the nuclear industry is the long-term confinement of nuclear waste. Because it is inexpensive and easy to manufacture, cement is the material of choice to store large volumes of radioactive materials, in particular the low-level medium-lived fission products. It is therefore of utmost importance to assess the chemical and structural stability of cement containing radioactive species. Here, we use ab initio calculations based on density functional theory (DFT) to study the effects of (90)Sr insertion and decay in C-S-H (calcium-silicate-hydrate) in order to test the ability of cement to trap and hold this radioactive fission product and to investigate the consequences of its β-decay on the cement paste structure. We show that (90)Sr is stable when it substitutes the Ca(2+) ions in C-S-H, and so is its daughter nucleus (90)Y after β-decay. Interestingly, (90)Zr, daughter of (90)Y and final product in the decay sequence, is found to be unstable compared to the bulk phase of the element at zero K but stable when compared to the solvated ion in water. Therefore, cement appears as a suitable waste form for (90)Sr storage.

Wood for fuel

Energy Technology Data Exchange (ETDEWEB)

Beaton, D

1986-01-01

Growing wood for energy could contribute three million tonnes of coal equivalent per year by the end of the century. Research programmes in the UK involved with energy forestry are reported. Three systems of wood energy, modified conventional forestry, single stem timber cropping and short rotation coppicing are being investigated. The short rotation coppicing requires inputs similar to those of agricultural crops and the machinery geared towards agricultural operations is compatible with it. Single stem forestry has a medium rotation period of 20 years. The production of coppice wood fuels is discussed in further detail for different parts of the UK with recommendations for species selection and adaption of existing farming practices. A coppice willow harvester has been developed for harvesting during November - February. Weed control and fertilizer application are also briefly mentioned.

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

Directory of Open Access Journals (Sweden)

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.

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.

Cement-Polymer Composite Containers for Radioactive Wastes Disposal

International Nuclear Information System (INIS)

Ghattas, N.K.; Eskander, S.B.; Bayoumi, T.A.; Saleh, H.M.

2009-01-01

Improving cement-composite containers using polymer as organic additives was studied extensively. Both unsaturated styrenated polyester (SPE) and polymethyl methacrylate (PMMA) were used to fill the pores in cement containers that used for disposal of radioactive wastes. Two different techniques were adopted for the addition of organic polymers based on their viscosity. The low density PMMA was added using impregnation technique. On the other hand high density SPE was mixed with cement paste as a premix process. Predetermined weight of dried borate radioactive powder waste simulate was introduced into the Cement-polymer composite (CPC) container and then closed before subjecting it to leaching characterization. The effect of the organic polymers on the hydration of cement matrix and on the properties of the obtained CPC container has been studied using X-ray diffraction, IR-analysis, thermal effects and weight loss. Porosity, pore parameters and rate of release were also determined. The results obtained showed that for the candidate CPC container positive effect of polymer dominates and an improvement in the retardation rate of PMMA release radionuclides was observed

Evaluation of wood structure using GPR with FO method - Effect of moisture, fibers direction and density

Science.gov (United States)

Chinh Maï, Tien; Reci, Hamza; Sbartaï, Zoubir Mehdi; Pajewski, Lara; Marciniak, Marian

2017-04-01

This work deals with the potential of GPR method in the evaluation of wood structure in relation with density of wood (different wood species), the orientation of fibers and water content (Maï et al., 2015; Reci et al., 2016). The system of measurements is the georadar type (GPR-ground penetrating radar) composed of an electromagnetic signal generator (SIR 3000 of GSSI), and one couple of antennas, one Transmitter (T) and a Receiver (R) of 1.5GHz center frequency, located in the same box in a fixed distance of 6cm. Six wood samples are tested, three samples of Epicea and three samples of Pine. To compare and analyze the results of dielectric constants, we have used the data on three principal directions (Transvesal, Longitudinal and Radial). We note that the dielectric constant of wood increases with the moisture by mass as a consequence of increasing polarization and the conduction phenomena. This effect is more distinguished when the electric field is polarized parallel to the fibers than in perpendicular direction. The smallest contrasts are observed in the radial direction. We conclude that is more appropriate to evaluate the water content along the parallel direction of fibers. In this case we observe the maximum of contrasts of dielectric contrasts between dry and humidity states. Differences on dielectric constant, spectras and amplitudes are taken between different wood samples. Knowing that the dielectric constant is related to the capacity of polarizing (dependent on the water quantity), the increasing of water content could explain the difference of values obtained for the dielectric constants between two kinds of wood. Acknowledgement The Authors are grateful to COST - European Cooperation in Science and Technology (www.cost.eu) for funding the Action TU1208 "Civil engineering applications of Ground Penetrating Radar" (www.GPRadar.eu). We acknowledge also the French National Research Agency (ANR) for supporting this study through the Xylo-plate project

Preliminary studies of Brazilian wood using different radioisotopic sources

International Nuclear Information System (INIS)

Carvalho, Gilberto; Silva, Leonardo Gondim de Andrade e

2013-01-01

Due to availability and particular features, wood was one of the first materials used by mankind with a wide variety of applications. It can be used as raw material for paper and cellulose manufacturing; in industries such as chemical, naval, furniture, sports goods, toys, and musical instrument; in building construction and in the distribution of electric energy. Wood has been widely researched; therefore, wood researchers know that several aspects such as temperature, latitude, longitude, altitude, sunlight, soil, and rainfall index interfere with the growth of trees. This behavior explains why average physical-chemical properties are important when wood is studied. The majority of researchers consider density to be the most important wood property because of its straight relationship with the physical and mechanical properties of wood. There are three types of wood density: basic, apparent and green. The apparent density was used here at 12% of moisture content. In this study, four different types of wood were used: 'freijo', 'jequetiba', 'muiracatiara' and 'ipe'. For wood density determination by non-conventional method, Am-241, Ba-133 and Cs-137 radioisotopic sources; a NaI scintillation detector and a counter were used. The results demonstrated this technique to be quick and accurate. By considering the nuclear parameters obtained as half value layers and linear absorption coefficients, Cs-137 radioisotopic source demonstrated to be the best option to be used for inspection of the physical integrity of electric wooden poles and live trees for future works. (author)

Terahertz Measurement of the Water Content Distribution in Wood Materials

Science.gov (United States)

Bensalem, M.; Sommier, A.; Mindeguia, J. C.; Batsale, J. C.; Pradere, C.

2018-02-01

Recently, THz waves have been shown to be an effective technique for investigating the water diffusion within porous media, such as biomaterial or insulation materials. This applicability is due to the sufficient resolution for such applications and the safe levels of radiation. This study aims to achieve contactless absolute water content measurements at a steady state case in semi-transparent solids (wood) using a transmittance THz wave range setup. First, a calibration method is developed to validate an analytical model based on the Beer-Lambert law, linking the absorption coefficient, the density of the solid, and its water content. Then, an estimation of the water content on a local scale in a transient-state case (drying) is performed. This study shows that THz waves are an effective contactless, safe, and low-cost technique for the measurement of water content in a porous medium, such as wood.

Effect of Alternative Wood Species and First Thinning Wood on Oriented Strand Board Performance

Directory of Open Access Journals (Sweden)

Fabiane Salles Ferro

2018-01-01

Full Text Available This study aimed to evaluate the feasibility of using and influence of alternative wood species such as Cambará, Paricá, Pinus, and wood from first thinning operations on oriented strand board (OSB physical and mechanical properties. Besides that, an alternative resin, castor oil-based polyurethane, was used to bond the particles, due to the better environmental performance when compared to other resins commonly used worldwide in OSB production. Physical properties such as the moisture content, thickness swelling, and water absorption, both after 2 and 24 hours of water immersion, and mechanical properties such as the modulus of elasticity and resistance in static bending, in major and minor axes, and internal bonding were investigated. All tests were performed according to European code EN 300:2006. Results showed the influence of wood species on physical and mechanical properties. Panels made with higher density woods such as Cambará presented better physical performance, while those made with lower density woods such as Pinus presented better mechanical properties. Besides that, strand particle geometry was also influenced on all physical and mechanical properties investigated. Therefore, the feasibility of using alternative species and wood from first thinning and with castor oil-based polyurethane resin in OSB production was verified.

Effect of the hydration temperature on the microstructure of Class G cement: C-S-H composition and density

International Nuclear Information System (INIS)

Bahafid, Sara; Ghabezloo, Siavash; Duc, Myriam; Faure, Pamela; Sulem, Jean

2017-01-01

Curing temperature has a significant influence on cement paste microstructure and the properties of its principal hydrate C-S-H. In this paper, the effect of the hydration temperature in the range of 7 °C to 90 °C on the microstructure of a class G oil-well cement is studied. This is done by combining various experimental methods, including X-ray diffraction associated with the Rietveld analysis, thermo-gravimetric analysis, mercury intrusion porosimetry and porosity evaluation by drying. The experimental results show an increase of the capillary porosity and a decrease of the gel porosity by increasing the hydration temperature. This is attributed to a decrease of the C-S-H intrinsic porosity and a corresponding increase of the C-S-H density for higher curing temperatures. The experimental results are used in a simple analysis method to evaluate the density of C-S-H, as well as its C/S ratio and H/S ratio in dry and saturated conditions. The evaluated C-S-H density varies from 1.88 g/cm 3 at 7 °C to 2.10 g/cm 3 at 90 °C. The results also show a decrease of molar C/S ratio with increasing hydration temperature from 1.93 at 7 °C to 1.71 at 90 °C and of the H/S ratio from 5.1 at 7 °C to 2.66 at 90 °C.

Plug cementing: Horizontal to vertical conditions

Energy Technology Data Exchange (ETDEWEB)

Calvert, D.G.; Heathman, J.F.; Griffith, J.E.

1995-12-31

This paper presents an in-depth study of cement plug placement that was conducted with large-scale models for the improvement of plug cementing practices and plug integrity. Common hole and workstring geometries were examined with various rheology and density ratios between the drilling fluid and cement. The critical conditions dictating the difference between success and failure for various wellbore angles and conditions were explored, and the mechanisms controlling slurry movement before and after placement are now better understood. An understanding of these mechanisms allows the engineer to better tailor a design to specific hole conditions. Controversial concepts regarding plug-setting practices have been examined and resolved. The cumulative effects of density, rheology, and hole angle are major factors affecting plug success. While the Boycott effect and an extrusion effect were observed to be predominant in inclined wellbores, a spiraling or {open_quotes}roping{close_quotes} effect controls slurry movement in vertical wellbores. Ultimate success of a cement plug can be obtained if allowances are made for these effects in the job design, provided all other previously published recommended placement practices are followed. Results of this work can be applied to many sidetracking and plug-to-abandon operations. Additionally, the understanding of the fluid movement (creep) mechanisms holds potential for use in primary and remedial cementing work, and in controlling the placement of noncementitious fluids in the wellbore.

Release of U(VI) from spent biosorbent immobilized in cement concrete blocks

Energy Technology Data Exchange (ETDEWEB)

Venkobachar, C.; Iyengar, L.; Mishra, U.K.; Chauhan, M.S. [Indian Inst. of Tech., Kanpur (India)

1995-12-01

This paper deals with cementation as the method for the disposal of spent biosorbent, Ganoderma lucidum (a wood rotting macrofungi) after it is used for the removal of Uranium. Results on the uranium release during the curing of cement-concrete (CC) blocks indicated that placing the spent sorbent at the center of the blocks during their casting yields better immobilization of uranium as compared to the homogeneous mixing of the spent sorbent with the cement. Short term leach tests indicated that the uranium release was negligible in simulated seawater, 1.8% in 0.2 N sodium carbonate and 6.0% in 0.2 N HCl. The latter two leachates were used to represent the extreme environmental conditions. It was observed that the presence of the spent biosorbent up to 5% by weight did not affect the compressive strength of CC blocks. Thus cementation technique is suitable for the immobilization of uranium loaded biosorbent for its ultimate disposal.

Release of U(VI) from spent biosorbent immobilized in cement concrete blocks

International Nuclear Information System (INIS)

Venkobachar, C.; Iyengar, L.; Mishra, U.K.; Chauhan, M.S.

1995-01-01

This paper deals with cementation as the method for the disposal of spent biosorbent, Ganoderma lucidum (a wood rotting macrofungi) after it is used for the removal of Uranium. Results on the uranium release during the curing of cement-concrete (CC) blocks indicated that placing the spent sorbent at the center of the blocks during their casting yields better immobilization of uranium as compared to the homogeneous mixing of the spent sorbent with the cement. Short term leach tests indicated that the uranium release was negligible in simulated seawater, 1.8% in 0.2 N sodium carbonate and 6.0% in 0.2 N HCl. The latter two leachates were used to represent the extreme environmental conditions. It was observed that the presence of the spent biosorbent up to 5% by weight did not affect the compressive strength of CC blocks. Thus cementation technique is suitable for the immobilization of uranium loaded biosorbent for its ultimate disposal

Bed agglomeration in fluidized combustor fueled by wood and rice straw blends

DEFF Research Database (Denmark)

Thy, Peter; Jenkins, Brian; Williams, R.B.

2010-01-01

Abstract Petrographic techniques have been used to examine bed materials from fluidized bed combustion experiments that utilized wood and rice straw fuel blends. The experiments were conducted using a laboratory-scale combustor with mullite sand beds, firing temperatures of 840 to 1030 °C, and run...... areas between bed particles, ultimately led to bed agglomeration. The interfaces and the presence of gas bubbles in the cement suggest a bonding material with a high surface tension and a liquid state. The cement films originate by filling of irregularities on individual and partially agglomerated bed...

Effect of light energy density on conversion degree and hardness of dual-cured resin cement.

Science.gov (United States)

Komori, Paula Carolina de Paiva; de Paula, Andréia Bolzan; Martin, Airton Abrāo; Tango, Rubens Nisie; Sinhoreti, Mario Alexandre Coelho; Correr-Sobrinho, Lourenço

2010-01-01

This study evaluated the effect of different light energy densities on conversion degree (CD) and Knoop hardness number (KHN) of RelyX ARC (RLX) resin cement. After manipulation according to the manufacturer's instructions, RLX was inserted into a rubber mold (0.8 mm x 5 mm) and covered with a Mylar strip. The tip of the light-curing unit (LCU) was positioned in contact with the Mylar surface. Quartz-tungsten-halogen (QTH) and light-emitting diode (LED) LCUs with light densities of 10, 20 and 30 J/cm2 were used to light-cure the specimens. After light curing, the specimens were stored dry in lightproof containers at 37 degrees C. After 24 hours, the CD was analyzed by FT-Raman and, after an additional 24-hours, samples were submitted to Knoop hardness testing. The data of the CD (%) and KHN were submitted to two-way ANOVA and the Tukey's test (alpha = 0.05). QTH and LED were effective light curing units. For QTH, there were no differences among the light energy densities for CD or KHN. For LED, there was a significant reduction in CD with the light energy density set at 10 J/cm2. KHN was not influenced by the light-curing unit and by its light energy density.

Flux Density through Guides with Microstructured Twisted Clad DB Medium

Directory of Open Access Journals (Sweden)

M. A. Baqir

2014-01-01

Full Text Available The paper deals with the study of flux density through a newly proposed twisted clad guide containing DB medium. The inner core and the outer clad sections are usual dielectrics, and the introduced twisted windings at the core-clad interface are treated under DB boundary conditions. The pitch angle of twist is supposed to greatly contribute towards the control over the dispersion characteristics of the guide. The eigenvalue equation for the guiding structure is deduced, and the analytical investigations are made to explore the propagation patterns of flux densities corresponding to the sustained low-order hybrid modes under the situation of varying pitch angles. The emphasis has been put on the effects due to the DB twisted pitch on the propagation of energy flux density through the guide.

Controls on Cementation in a Chalk Reservoir

DEFF Research Database (Denmark)

Meireles, Leonardo Teixeira Pinto; Hussein, A.; Welch, M.J.

2017-01-01

In this study, we identify different controls on cementation in a chalk reservoir. Biot’s coefficient, a measure of cementation, stiffness and strength in porous rocks, is calculated from logging data (bulk density and sonic Pwave velocity). We show that Biot’s coefficient is correlated...... that some degree of pore filling cementation occurred in Kraka (Alam, 2010). Lack of correlation between Biot’s coefficient and Gamma Ray (GR) indicates that the small amount of clay present is generally located in the pore space, thus not contributing to frame stiffness. While there was no compositional...... control on cementation via clay, we could infer that stratigraphy impacts on the diagenetic process....

HIGH RESOLUTION MICROTOMOGRAPHY FOR DENSITY AND SPATIAL INFORMATION ABOUT WOOD STRUCTURES.

Energy Technology Data Exchange (ETDEWEB)

ILLMAN,B.

1999-07-22

Microtomography has successfully been used to characterize loss of structural integrity of wood. Tomographic images were generated with the newly developed third generation x-ray computed microtomography (XCMT) instrument at the X27A beamline at the National Synchrotron Light Source (NSLS). The beamline is equipped with high-flux x-ray monochromator based on multilayer optics developed for this application. The sample is mounted on a translation stage with which to center the sample rotation, a rotation stage to perform the rotation during data collection and a motorized goniometer head for small alignment motions. The absorption image is recorded by a single-crystal scintillator, an optical microscope and a cooled CCD array detector. Data reconstruction has provided three-dimensional geometry of the heterogeneous wood matrix in microtomographic images. Wood is a heterogeneous material composed of long lignocellulose vessels. Although wood is a strong natural product, fungi have evolved chemical systems that weaken the strength properties of wood by degrading structural vessels. Tomographic images with a resolution of three microns were obtained nonintrusively to characterize the compromised structural integrity of wood. Computational tools developed by Lindquist et al (1996) applied to characterize the microstructure of the tomographic volumes.

Forming a constant density medium close to long gamma-ray burst

NARCIS (Netherlands)

Marle, A.J.; Langer, N.; Achterberg, A; Garia-Segura, G.

2006-01-01

Aims. The progenitor stars of long Gamma-Ray Bursts (GRBs) are thought to be Wolf-Rayet stars, which generate a massive and energetic wind. Nevertheless, about 25 percent of all GRB afterglows light curves indicate a constant density medium close to the exploding star. We explore various ways to

Full factorial design analysis of carbon nanotube polymer-cement composites

Directory of Open Access Journals (Sweden)

Fábio de Paiva Cota

2012-08-01

Full Text Available The work described in this paper is related to the effect of adding carbon nanotubes (CNT on the mechanical properties of polymer-cement composites. A full factorial design has been performed on 160 samples to identify the contribution provided by the following factors: polymeric phase addition, CNT weight addition and water/cement ratio. The response parameters of the full factorial design were the bulk density, apparent porosity, compressive strength and elastic modulus of the polymer-cement-based nanocomposites. All the factors considered in this analysis affected significantly the bulk density and apparent porosity of the composites. The compressive strength and elastic modulus were affected primarily by the cross-interactions between polymeric phase and CNT additions, and the water/cement ratio with polymeric phase factors.

Durability of pulp fiber-cement composites

Science.gov (United States)

Mohr, Benjamin J.

Wood pulp fibers are a unique reinforcing material as they are non-hazardous, renewable, and readily available at relatively low cost compared to other commercially available fibers. Today, pulp fiber-cement composites can be found in products such as extruded non-pressure pipes and non-structural building materials, mainly thin-sheet products. Although natural fibers have been used historically to reinforce various building materials, little scientific effort has been devoted to the examination of natural fibers to reinforce engineering materials until recently. The need for this type of fundamental research has been emphasized by widespread awareness of moisture-related failures of some engineered materials; these failures have led to the filing of national- and state-level class action lawsuits against several manufacturers. Thus, if pulp fiber-cement composites are to be used for exterior structural applications, the effects of cyclical wet/dry (rain/heat) exposure on performance must be known. Pulp fiber-cement composites have been tested in flexure to examine the progression of strength and toughness degradation. Based on scanning electron microscopy (SEM), environmental scanning electron microscopy (ESEM), energy dispersive spectroscopy (EDS), a three-part model describing the mechanisms of progressive degradation has been proposed: (1) initial fiber-cement/fiber interlayer debonding, (2) reprecipitation of crystalline and amorphous ettringite within the void space at the former fiber-cement interface, and (3) fiber embrittlement due to reprecipitation of calcium hydroxide filling the spaces within the fiber cell wall structure. Finally, as a means to mitigate kraft pulp fiber-cement composite degradation, the effects of partial portland cement replacement with various supplementary cementitious materials (SCMs) has been investigated for their effect on mitigating kraft pulp fiber-cement composite mechanical property degradation (i.e., strength and toughness

Studies Involving Immobilization Of Hazardous Wastes In Cement-ilmenite Matrix

International Nuclear Information System (INIS)

El-Dakrory, A.M.; Sayed, M.S.; Adham, K.

1999-01-01

Ilmenite was added to Ordinary Portland Cement to Modify the characteristic properties of the matrix as density, compressive strength and thermal stability . Coal tar and radiocesium were solidified as hazardous waste in cement-ilmenite matrix. The physical properties as density, sitting times and porosity were studied. The mechanical properties as compressive strength values and the chemical properties as leaching were measured

BEHAVIOR OF GLUED JOINTS OF EUCALYPTUS sp. SAWN WOOD

Directory of Open Access Journals (Sweden)

Octávio Barbosa Plaster

2008-09-01

Full Text Available This research evaluated eucalypt wood adhesion capacity. The material evaluated was a commercial sawn wood composed by a blend of species of the genus Eucalyptus. The adhesives used were resorcinol-formaldehyde and polyvinila acetate (PVAc. The wood was segregated in three density with 0% of moisture content: class 1; 2 and 3 that, when combined (class1 x class1; 2x2; 3x3; 1x2; 1x3; 2x3 resulted in six treatments. The performance of the adhesion was evaluated by the shear strength to parallel compression and by wood failure in the glue line. The obtained results allowed to conclude that the adhesion of the combinations of wood/adhesive presented satisfactory performance. The average shear strength of the joints were shown equivalent to the shear strength of the solid wood with similar performance of adhesion in the two adhesives. In general, resorcinol-formaldheyde adhesive presented higher values (74.41% for wood failure in the joints, but similar to all treatments. The adhesion of samples of higher density presented lower performance probably when only the values of wood failure are considered. The values for the strength of glued joints, in general, were similar when analyzed the results achieved with the resorcinol-formaldehyde adhesive- base 140,56 Kgf/cm2. To polyvinila acetate the values of wood failure decrease when the density increase (65.94%, but the resistance in the glue line was positively affected (140.25 Kgf/cm2. In general, the density influenced the adhesion of the joints for the employed adhesives.

Preliminary studies of Brazilian wood using different radioisotopic sources

Energy Technology Data Exchange (ETDEWEB)

Carvalho, Gilberto; Silva, Leonardo Gondim de Andrade e, E-mail: gcarval@ipen.br, E-mail: ftgasilva@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2013-07-01

Due to availability and particular features, wood was one of the first materials used by mankind with a wide variety of applications. It can be used as raw material for paper and cellulose manufacturing; in industries such as chemical, naval, furniture, sports goods, toys, and musical instrument; in building construction and in the distribution of electric energy. Wood has been widely researched; therefore, wood researchers know that several aspects such as temperature, latitude, longitude, altitude, sunlight, soil, and rainfall index interfere with the growth of trees. This behavior explains why average physical-chemical properties are important when wood is studied. The majority of researchers consider density to be the most important wood property because of its straight relationship with the physical and mechanical properties of wood. There are three types of wood density: basic, apparent and green. The apparent density was used here at 12% of moisture content. In this study, four different types of wood were used: 'freijo', 'jequetiba', 'muiracatiara' and 'ipe'. For wood density determination by non-conventional method, Am-241, Ba-133 and Cs-137 radioisotopic sources; a NaI scintillation detector and a counter were used. The results demonstrated this technique to be quick and accurate. By considering the nuclear parameters obtained as half value layers and linear absorption coefficients, Cs-137 radioisotopic source demonstrated to be the best option to be used for inspection of the physical integrity of electric wooden poles and live trees for future works. (author)

FLEXURAL TESTING OF WOOD-CONCRETE COMPOSITE BEAM MADE FROM KAMPER AND BANGKIRAI WOOD

Directory of Open Access Journals (Sweden)

Fengky Satria Yoresta

2015-07-01

Full Text Available Certain wood has a tensile strength that almost equal with steel rebar in reinforced concrete beams. This research aims to understand the capacity and flexural behavior of concrete beams reinforced by wood (wood-concrete composite beam. Two different types of beams based on placement positions of wood layers are proposed in this study. Two kinds of wood used are consisted of Bangkirai (Shorea laevifolia and Kamper (Cinnamomum camphora, meanwhile the concrete mix ratio for all beams is 1 cement : 2 fine aggregates : 3 coarse aggregates. Bending test is conducted by using one-point loading method. The results show that composite beam using Bangkirai wood is stronger than beams using Kamper wood. More thicker wood layer in tensile area will increase the flexural strength of beams. Crack patterns identified could be classified into flexural cracks, shear cracks, and split on wood layer   Beberapa jenis kayu tertentu memiliki kekuatan tarik yang hampir sama dengan tulangan baja pada balok beton bertulang. Penelitian ini bertujuan memahami kapasitas dan perilaku lentur balok beton bertulang yang diperkuat menggunakan kayu (balok komposit beton-kayu. Dua tipe balok yang berbeda berdasarkan posisi penempatan kayu digunakan dalam penelitian ini. Dua jenis kayu yang digunakan adalah kayu Bangkirai (Shorea laevifolia and Kamper (Cinnamomum camphora, sementara itu rasio campuran beton untuk semua balok menggunakan perbandingan 1 semen : 2 agregat halus : 3 agregat kasar. Pengujian lentur dilakukan menggunakan metode one-point loading. Hasil penelitian menunjukkan bahwa balok komposit dengan kayu Bangkirai lebih kuat dibandingkan balok dengan kayu Kamper. Semakin tebal lapisan kayu yang berada di daerah tarik akan meningkatkan kekuatan lentur balok. Pola kerusakan yang teridentifikasi dapat diklasifikasikan menjadi retak lentur, retak geser, dan pecah pada kayu REFERENCES Boen T. (2010. Retrofitting Simple Buildings Damaged by Earthquakes. World Seismic

Manufacturing methods and magnetic characteristics of magnetic wood

International Nuclear Information System (INIS)

Oka, H.; Hojo, A.; Osada, H.; Namizaki, Y.; Taniuchi, H.

2004-01-01

The relationship between wood construction and DC magnetic characteristics for three types of magnetic wood was experimentally investigated. The results show that the magnetic characteristics of each type of magnetic wood are dependent on the magnetic materials, the density of the magnetic material and the construction of the wood. Furthermore, it was determined that the relationship between the fiber direction and the magnetic path direction of the magnetic wood influenced the wood's magnetic characteristics

Effect of uniaxially pressing ordinary Portland cement pastes containing metal hydroxides on porosity, density, and leaching

International Nuclear Information System (INIS)

Cheeseman, C.R.; Asavapisit, S.; Knight, J.

1998-01-01

Synthetic metal hydroxide wastes containing Zn and Pb have been mixed with partially hydrated cement and uniaxially pressed. The effect on porosity, pore size distribution, and bulk and skeletal densities has been characterized using mercury intrusion porosimetry. Ca(OH) 2 formation has been determined using differential thermal analysis and metal leaching has been assessed in a series of static leach tests completed on monolithic samples. Pressed solidified materials have increased density, reduced porosity, and reduced Ca(OH) 2 . They exhibit increased resistance to acid attack in terms of sample weight loss during leaching due to reduced release of alkalis. Leaching of Zn and Pb is primarily determined by pH. A peak observed in Zn leaching from pressed samples is due to the effect of changing leachate pH on the dominant Zn species present

Implementing Strategies for Drying and Pressing Wood Without Emissions Controls

Energy Technology Data Exchange (ETDEWEB)

Sujit Banerjee; Terrance Conners

2007-09-07

Drying and pressing wood for the manufacture of lumber, particleboard, oriented strand board (OSB), veneer and medium density fiberboard (MDF) release volatile organic compounds (VOCs) into the atmosphere. These emissions require control equipment that are capital-intensive and consume significant quantities of natural gas and electricity. The objective of our work was to understand the mechanisms through which volatile organic compounds are generated and released and to develop simple control strategies. Of the several strategies developed, two have been implemented for OSB manufacture over the course of this study. First, it was found that increasing final wood moisture by about 2-4 percentage points reduced the dryer emissions of hazardous air pollutants by over 70%. As wood dries, the escaping water evaporatively cools the wood. This cooling tapers off wood when the wood is nearly dry and the wood temperature rises. Thermal breakdown of the wood tissue occurs and VOCs are released. Raising the final wood moisture by only a few percentage points minimizes the temperature rise and reduces emissions. Evaporative cooling also impacts has implications for VOC release from wood fines. Flaking wood for OSB manufacture inevitable generates fines. Fines dry out rapidly because of their high surface area and evaporative cooling is lost more rapidly than for flakes. As a result, fines emit a disproportionate quantity of VOCs. Fines can be reduced in two ways: through screening of the green furnish and through reducing their generation during flaking. The second approach is preferable because it also increased wood yield. A procedure to do this by matching the sharpness angle of the flaker knife to the ambient temperature was also developed. Other findings of practical interests are as follows: Dielectric heating of wood under low-headspace conditions removes terpenes and other extractives from softwood; The monoterpene content in trees depend upon temperature and seasonal

EFFECTS OF LEACHING MEDIUM ON LEACHABILITY OF WOOD PRESERVING N'N-HYDROXYNAPTHALIMIDE (NHA)

OpenAIRE

Evren Terzi,; Dilek Dogu,; Feyza Kurt,; S. Nami Kartal,; Frederick Green

2012-01-01

Laboratory leaching test procedures usually call for the use of distilled or deionized water; however, treated wood is generally exposed to different types of water, soil, and weather conditions. Thus, factors such as salinity, hardness, pH, temperature etc. might be important in the release of different amounts of biocide compounds. This study evaluates the release of the sodium salt of the calcium precipitating and wood preserving agent N’N-hydroxynapthalimide (NHA) from treated wood specim...

Biomaterial based novel polyurethane adhesives for wood to wood and metal to metal bonding

Directory of Open Access Journals (Sweden)

Mitesh Ramanlal Patel

2009-01-01

Full Text Available Polyurethane adhesives made from synthetic chemicals are non-biodegradable, costly and difficult to find raw materials from local market. To avoid solid pollution problem, cost effectiveness and easy availability of raw materials, biomaterials based polyurethane adhesives are used in current industrial interest. Direct use of castor oil in polyurethane adhesive gives limited hardness. Modification on active sites of castor oil to utilize double bond of unsaturated fatty acid and carboxyl group yields new modified or activated polyols, which can be utilized for polyurethane adhesive formulation. In view of this, we have synthesized polyurethane adhesives from polyester polyols, castor oil based polyols and epoxy based polyols with Isocyanate adducts based on castor oil and trimethylolpropane. To study the effects of polyurethane adhesive strength (i.e. lap shear strength on wood-to-wood and metal-to-metal bonding through various types of polyols, cross-linking density, isocyanate adducts and also to compare adhesive strength between wood to wood and metal to metal surface. These polyols and polyurethanes were characterized through GPC, NMR and IR-spectroscopy, gel and surface drying time. Thermal stability of PU adhesives was determined under the effect of cross-linking density (NCO/OH ratio. The NCO/OH ratio (1.5 was optimized for adhesives as the higher NCO/OH ratio (2.0 increasing cross-linking density and decreases adhesion. Lower NCO/OH ratio (1.0 provideslow cross-linking density and low strength of adhesives.

Influence of reinforcement and cemented parts on quality of radiological shields

International Nuclear Information System (INIS)

Ablewicz, Z.

1974-01-01

Results of studies of the influence of reinforcement density and shape of cemented parts on quality of radiological shields are presented. The studies were carried out on built shields and on experimental blocks. The experimental studies were aimed at determination of filling degree under cemented parts of different shapes using two kinds of cement normal and heavy one and at determination of filling degree of space with dense reinforcement as well as space near boarding. The influence of reinforcement density was studied using different spacing between bars and rows of bars. In the case of difficulties with good filling under the cemented parts so called ''beard'' and more liquid mixtures were used with success. (Z.M.)

Effect of Nano bentonite on Fire Retardant Properties of Medium density fiberboard (MDF

Directory of Open Access Journals (Sweden)

Ghonche Rassam

2014-05-01

Full Text Available In the present study, Fire – Retarding properties of nano-bentonite in medium density of fiberboard (MDF was studied. 10% of urea-formaldehyde resin was used as the adhesive of the matrix. Nano Bentonite at 5 levels (0%, 5%, 10%, 15% and 20% g/kg based of dry weight of fibers was used with the consumption of Urea-Formuldehyde (UF. Press pressure of 150 bar and temperature of 170during 4, 5, and 6 minutes were applied. Density was kept constant at 0.7 g/cm3 in all treatments. The measured properties consisted of mass reduction, inflammation time, fire-endurance, melting time and the burnt area. The results revealed that Nano-Bentonite had significant effect in approving fire retarding properties in medium density fiber board. The best properties at the level of 10% obtained and the same level recommended for industry use. The use of Nano-Bentonite more than 10% decreased the stickiness and the partly surface of fiberboards.

Evaluation of changes in vertebral body density following administration of contrast medium during routine CT examination

International Nuclear Information System (INIS)

Janicek, M.; Bruna, J.; Stenhova, H.

1984-01-01

The possibility is discussed of depicting changes in the density of spongiosis of the vertebral body in normal patients after intravenous administration of a bolus of 40 ml 60% Diazetrizoate in the course of a routine CT examination. The average increase in density immediately after the administration of the contrast medium is 12 H (8%), in the course of 10 minutes is reduced to 5 H (4%) against the initial values in native examination. These average changes are statistically significant, in individual patients, however, the increase in density following the administration of a contrast medium fluctuates considerably (from 0.7% to 10%). Only systematic comparison with various pathological conditions will make it possible to assess the possibilities of the evaluation of the structure of the vertebral body in routine CT with the administration of a contrast medium into the blood flow. (author)

Influence of Superplasticizer-Microsilica Complex on Cement Hydration, Structure and Properties of Cement Stone

Science.gov (United States)

Ivanov, I. M.; Kramar, L. Ya; Orlov, A. A.

2017-11-01

According to the study results, the influence of complex additives based on microsilica and superplasticizers on the processes of the heat release, hydration, hardening, formation of the structure and properties of cement stone was determined. Calorimetry, derivatography, X-ray phase analysis, electronic microscopy and physical-mechanical methods for analyzing the properties of cement stone were used for the studies. It was established that plasticizing additives, in addition to the main water-reducing and rheological functions, regulate cement solidification and hardening while polycarboxylate superplasticizers even contribute to the formation of a special, amorphized microstructure of cement stone. In a complex containing microsilica and a polycarboxylate superplasticizer the strength increases sharply with a sharp drop in the capillary porosity responsible for the density, permeability, durability, and hence, the longevity of concrete. All this is a weighty argument in favor of the use of microsilica jointly with a polycarboxylate superplasticizer in road concretes operated under aggressive conditions.

29 CFR 1910.25 - Portable wood ladders.

Science.gov (United States)

2010-07-01

... for the construction, care, and use of the common types of portable wood ladders, in order to insure... density wood shall not be used. (ii) [Reserved] (2) [Reserved] (c) Construction requirements. (1... 29 Labor 5 2010-07-01 2010-07-01 false Portable wood ladders. 1910.25 Section 1910.25 Labor...

Wood Specific Gravity Variations and Biomass of Central African Tree Species: The Simple Choice of the Outer Wood.

Directory of Open Access Journals (Sweden)

Jean-François Bastin

Full Text Available Wood specific gravity is a key element in tropical forest ecology. It integrates many aspects of tree mechanical properties and functioning and is an important predictor of tree biomass. Wood specific gravity varies widely among and within species and also within individual trees. Notably, contrasted patterns of radial variation of wood specific gravity have been demonstrated and related to regeneration guilds (light demanding vs. shade-bearing. However, although being repeatedly invoked as a potential source of error when estimating the biomass of trees, both intraspecific and radial variations remain little studied. In this study we characterized detailed pith-to-bark wood specific gravity profiles among contrasted species prominently contributing to the biomass of the forest, i.e., the dominant species, and we quantified the consequences of such variations on the biomass.Radial profiles of wood density at 8% moisture content were compiled for 14 dominant species in the Democratic Republic of Congo, adapting a unique 3D X-ray scanning technique at very high spatial resolution on core samples. Mean wood density estimates were validated by water displacement measurements. Wood density profiles were converted to wood specific gravity and linear mixed models were used to decompose the radial variance. Potential errors in biomass estimation were assessed by comparing the biomass estimated from the wood specific gravity measured from pith-to-bark profiles, from global repositories, and from partial information (outer wood or inner wood.Wood specific gravity profiles from pith-to-bark presented positive, neutral and negative trends. Positive trends mainly characterized light-demanding species, increasing up to 1.8 g.cm-3 per meter for Piptadeniastrum africanum, and negative trends characterized shade-bearing species, decreasing up to 1 g.cm-3 per meter for Strombosia pustulata. The linear mixed model showed the greater part of wood specific gravity

Wood Specific Gravity Variations and Biomass of Central African Tree Species: The Simple Choice of the Outer Wood.

Science.gov (United States)

Bastin, Jean-François; Fayolle, Adeline; Tarelkin, Yegor; Van den Bulcke, Jan; de Haulleville, Thales; Mortier, Frederic; Beeckman, Hans; Van Acker, Joris; Serckx, Adeline; Bogaert, Jan; De Cannière, Charles

2015-01-01

Wood specific gravity is a key element in tropical forest ecology. It integrates many aspects of tree mechanical properties and functioning and is an important predictor of tree biomass. Wood specific gravity varies widely among and within species and also within individual trees. Notably, contrasted patterns of radial variation of wood specific gravity have been demonstrated and related to regeneration guilds (light demanding vs. shade-bearing). However, although being repeatedly invoked as a potential source of error when estimating the biomass of trees, both intraspecific and radial variations remain little studied. In this study we characterized detailed pith-to-bark wood specific gravity profiles among contrasted species prominently contributing to the biomass of the forest, i.e., the dominant species, and we quantified the consequences of such variations on the biomass. Radial profiles of wood density at 8% moisture content were compiled for 14 dominant species in the Democratic Republic of Congo, adapting a unique 3D X-ray scanning technique at very high spatial resolution on core samples. Mean wood density estimates were validated by water displacement measurements. Wood density profiles were converted to wood specific gravity and linear mixed models were used to decompose the radial variance. Potential errors in biomass estimation were assessed by comparing the biomass estimated from the wood specific gravity measured from pith-to-bark profiles, from global repositories, and from partial information (outer wood or inner wood). Wood specific gravity profiles from pith-to-bark presented positive, neutral and negative trends. Positive trends mainly characterized light-demanding species, increasing up to 1.8 g.cm-3 per meter for Piptadeniastrum africanum, and negative trends characterized shade-bearing species, decreasing up to 1 g.cm-3 per meter for Strombosia pustulata. The linear mixed model showed the greater part of wood specific gravity variance was

Determination of density profiles of unevenly compressed wood of Po­pu­lus tremula using the X – RAY DENSE – LAB laboratory device

Directory of Open Access Journals (Sweden)

Aleš Dejmal

2009-01-01

Full Text Available The paper deals with the measuring of the density profile of unevenly pressed wood of European aspen (Populus tremula L.. The main aim of the work is to examine in an experimental way the possibilities of using the X – RAY DENSE – LAB laboratory equipment designed for the determination of density profiles of agglomerated and plied large-area materials. The work uses the X – RAY DENSE – LAB equipment to determine the density profile of the cross-section of unevenly pressed aspen wood, plasticized hydrothermically, without the presence of chemical substances. The work also presents calculations of the level of compression/densification in dependence on the density and it describes the factors that can influence the density profile of compressed/densified wood; at the same time, it presents the possible ways to determine the density profile in the cross-section. Further, it includes the creation of the methodology for sample preparation so that the results do not get distorted during measuring. It describes the preparation of sample pieces, the orientation of the anatomic structure, the methodology of pressing, air conditioning, sample preparation, their measuring and analysis. The paper also describes the theory and the principles of measuring with use of X – RAY DENSE – LAB and its calibration. The paper analyses the obtained results of density profiles and searches for and describes the causes of the uneven distribution of the density in the cross-section. It concludes by summarizing the results and recommending the procedure for future measuring.

Radial variation of basic density and wood cells dimensions of Cariniana legalis (Mart. O. Kuntze depending on the provenance

Directory of Open Access Journals (Sweden)

Israel Luiz de Lima

2011-12-01

Full Text Available Provenance tests can provide information about the silvicultural behavior and wood quality for the exploration of variability and conservation of genetic material for future use. This study aims to investigate the effect of provenances on some wood properties of the Cariniana legalis. Seedlings of three provenances (Porto Ferreira, Piracicaba and Campinas were planted in Luiz Antonio-SP using randomized block design with six replicates. After 26 years of planting, eighteen trees, six of each provenance, were felled. The properties studied were basic density and the cellular dimensions. The results revealed that the basic density, fiber length, fiber wall thickness, vessel element length, vessel diameter, uniseriate ray height and width were influenced by the provenances. A good positive relationship was found among the fiber length, fiber wall thickness, vessel element length; vessel diameter and multiseriate ray height with radial position and a negative relation between vessel frequency with the radial position.

Apparatus for manufacturing ceramics microspheres for cementing applications

NARCIS (Netherlands)

2012-01-01

A method and apparatus for manufacturing ceramic microspheres from industrial slag. The micro spheres have a particle size of about 38 microns to about 150 microns. The microspheres are used to create a cement slurry having a density of at least about Illbs/g. The resultant cement slurry may then be

Modified sulphur cement: A low porosity encapsulation material for low, medium and alpha waste

International Nuclear Information System (INIS)

Dalen, A. van; Rijpkema, J.E.

1989-01-01

Modified sulphur cement, available under the trade name Chement 2000, is a thermoplastic candidate material for the matrix of low, intermediate and alpha radioactive waste. The main source of sulphur is the desulphurization of fossil fuels. In view of the future increase of this product a modified compound of sulphur has been developed at the US Bureau of Mines. Modified sulphur cement as matrix material has properties in common with Portland or blast furnace cement and bitumen. The mechanical strength is comparable to hydraulic cement products. The process to incorporate waste materials is identical to bitumization. The leachability and the resistance to attack by chemicals is nearly the same as for bituminized products. This study showed also that the radiation resistance is high without radiolytic gas production and without change in dimensions (swelling). The rigidity of the matrix is a disadvantage when internal pressures are built up. The thermal conductivity and the heat of combustion of sulphur is low resulting in slow damage to the waste form under fire conditions, even when the temperature of self ignition in air is 220 0 C. The low leachability, the very slow effective diffusion of H 2 O and HTO, and the low permeability is due to the small pore diameters in the modified sulphur matrix. The loading capacity of modified sulphur cement depends on grain size and distribution and is for ungraded ashes, precipitates, dried sludges, etc., in the order of 40-50% of weight. The price of Chement 2000 per tonne is equal to those of blown bitumen

Developing wood construction in France in order to enhance energy independence, reduce greenhouse gas emissions and develop employment

International Nuclear Information System (INIS)

2015-05-01

In France, forests represent a third of the surface of the whole country, whereas the national commercial balance on transformed wood shows a large deficit. A well designed development of wood production and transformation for the construction sector could induce many beneficial effects: diminution of greenhouse gas (CO_2) emissions related to the production of construction materials (cement, steel); substitution of a part of space heating fuels by wood collection and transformation by-products and wastes; and decrease of imports of hydrocarbons (through fuel substitution) and transformed woods (through a better transformation in France of timbers grown in French forests). Some recommendations concerning the development of the wood construction sector are given

The incorporation of low and medium level radioactive wastes (solids and liquids) in cement

International Nuclear Information System (INIS)

Brown, D.J.; Capp, P.D.; Smith, D.L.

1982-08-01

Laboratory studies and mixing plant trials on simulated radioactive waste formulations are reported. Long term stability testing of various formulations including those containing blast furnace slag-ordinary Portland cement, sodium nitrate, ion exchange resins, and sodium nitrate-tributyl phosphate, are reported and some results are given. Mixing plant trials with a high shear cement mixer are reported. An outline of future work is presented. (U.K.)

Process for carbonizing coal, shale, wood, etc

Energy Technology Data Exchange (ETDEWEB)

Matthaei, K

1924-05-08

A process for carbonization of coal, shale, and wood, for recovering low temperature tar and other products in a rotary retort is described. The material to be carbonized is brought directly in contact with the heating medium, that is characterized in that the heating medium streams through the retort crosswise to the longitudinal axis. The temperature of this medium in the single retort segments can be regulated.

Wood-plastic composites utilizing wood flours derived from fast- growing trees common to the midwest

Science.gov (United States)

There are several non- or under-utilized hardwood trees common to the Midwestern states. Wood flour (WF) derived from fast-growing Midwest trees (Osage orange, Black Locust and Red Mulberry) were evaluated as a source of bio-based fiber reinforcements. Wood plastic composites (WPC) of high density p...

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

Intraspecific variability of European larch for wood properties: Preliminary results

Energy Technology Data Exchange (ETDEWEB)

Paques, L.E.; Rozenberg, P. [Institut National de Recherches Agronomiques (INRA), 45 - Olivet (France). Station d`Amelioration des Arbres Forestiers

1995-12-31

Wood properties of several natural populations of European larch (Larix decidua Mill) were determined from samples collected in one replicate of the II. International IUFRO provenance experiment, planted in Brittany in 1959. According to provenances, proportion of heartwood ranges from 35 to 58% of basal area, basic density from 442 to 505 g/dm{sup 3} and Young modulus of elasticity from 8474 to 14522 MPa. Positive correlations between girth and heartwood proportion and between wood density and modulus of elasticity but negative correlations between ring width and both density and MOE have been found both at the individual and at the population levels. Variability between and within provenances is high for two major traits (proportion of heartwood and Young modulus of elasticity) for which a SW - NE gradient is shown. For wood density parameters including pilodyn, a greater homogeneity is observed. Besides a now largely recognized superiority for growth traits, Central European populations from the Sudetan Mountains and Central Poland would also produce wood with better properties. On the reverse, Alpine populations from the French Alps growing at low elevations have a slower growth, a denser wood with less heartwood and less strength. Used as a control, the hybrid larch origin (Larix x eurolepis) represents the best compromise for wood properties with the highest strength but an average wood density and one of the highest proportion of heartwood. These preliminary results must be confirmed from a larger set of provenances and completed with other major wood properties such as durability and shrinkage. 17 refs, 2 figs, 6 tabs

Intraspecific variability of European larch for wood properties: Preliminary results

Energy Technology Data Exchange (ETDEWEB)

Paques, L E; Rozenberg, P [Institut National de Recherches Agronomiques (INRA), 45 - Olivet (France). Station d` Amelioration des Arbres Forestiers

1996-12-31

Wood properties of several natural populations of European larch (Larix decidua Mill) were determined from samples collected in one replicate of the II. International IUFRO provenance experiment, planted in Brittany in 1959. According to provenances, proportion of heartwood ranges from 35 to 58% of basal area, basic density from 442 to 505 g/dm{sup 3} and Young modulus of elasticity from 8474 to 14522 MPa. Positive correlations between girth and heartwood proportion and between wood density and modulus of elasticity but negative correlations between ring width and both density and MOE have been found both at the individual and at the population levels. Variability between and within provenances is high for two major traits (proportion of heartwood and Young modulus of elasticity) for which a SW - NE gradient is shown. For wood density parameters including pilodyn, a greater homogeneity is observed. Besides a now largely recognized superiority for growth traits, Central European populations from the Sudetan Mountains and Central Poland would also produce wood with better properties. On the reverse, Alpine populations from the French Alps growing at low elevations have a slower growth, a denser wood with less heartwood and less strength. Used as a control, the hybrid larch origin (Larix x eurolepis) represents the best compromise for wood properties with the highest strength but an average wood density and one of the highest proportion of heartwood. These preliminary results must be confirmed from a larger set of provenances and completed with other major wood properties such as durability and shrinkage. 17 refs, 2 figs, 6 tabs

Effects of gamma irradiation on polypropylene, polypropylene + high density polyethylene and polypropylene + high density polyethylene + wood flour

Energy Technology Data Exchange (ETDEWEB)

Reyes, J.; Albano, C.; Davidson, E.; Poleo, R. [Universidad Central de Venezuela, Caracas (Venezuela). Escuela de Quimica; Gonzalez, J.; Ichazo, M. [Universidad Simon Bolivar, Dept. de Mecanica, Caracas (Venezuela); Chipara, M. [Research Institute for Electrotechnics, Bucharest (Romania)

2001-04-01

The effect of the gamma-irradiation on the mechanical properties of the composites, Polypropylene (PP), PP+high density Polyethylene (HDPE), PP+ HDPE+wood flour, where HDPE is virgin and recycled, was studied. This paper discusses the behavior of the composites after exposure to various doses of gamma irradiation (1-7 MRads) in the presence of oxygen. The dependence of mechanical properties on the integral dose for a constant dose rate of 0.48 MRads/h confirms the influence of the irradiation. Strong effects on the elongation at break and break strength is noticed. The mathematical analysis suggests for the PP+r-HDPE a bimolecular process of the elongation at break. On the order hand, for the PP+HDPE a complex process is represented for a three exponential equation. (orig.)

Effects of gamma irradiation on polypropylene, polypropylene + high density polyethylene and polypropylene + high density polyethylene + wood flour

International Nuclear Information System (INIS)

Reyes, J.; Albano, C.; Davidson, E.; Poleo, R.; Chipara, M.

2001-01-01

The effect of the gamma-irradiation on the mechanical properties of the composites, Polypropylene (PP), PP+high density Polyethylene (HDPE), PP+ HDPE+wood flour, where HDPE is virgin and recycled, was studied. This paper discusses the behavior of the composites after exposure to various doses of gamma irradiation (1-7 MRads) in the presence of oxygen. The dependence of mechanical properties on the integral dose for a constant dose rate of 0.48 MRads/h confirms the influence of the irradiation. Strong effects on the elongation at break and break strength is noticed. The mathematical analysis suggests for the PP+r-HDPE a bimolecular process of the elongation at break. On the order hand, for the PP+HDPE a complex process is represented for a three exponential equation. (orig.)

The effects of the recent minimum temperature and water deficit increases on Pinus pinaster wood radial growth and density in southern Portugal.

Directory of Open Access Journals (Sweden)

Cathy Béatrice Kurz Besson

2016-08-01

Full Text Available Western Iberia has recently shown increasing frequency of drought conditions coupled with heatwave events, leading to exacerbated limiting climatic conditions for plant growth. It is not clear to what extent wood growth and density of agroforestry species have suffered from such changes or recent extreme climate events.To address this question, tree-ring width and density chronologies were built for a P. pinaster stand in southern Portugal and correlated with climate variables, including the minimum, mean and maximum temperatures and the number of cold days. Monthly and maximum daily precipitations were also analyzed as well as dry spells. The drought effect was assessed using the standardized precipitation-evapotranspiration (SPEI multi-scalar drought index, between 1 to 24-months. The climate-growth/density relationships were evaluated for the period 1958-2011.We show that both wood radial growth and density highly benefit from the strong decay of cold days and the increase of minimum temperature. Yet the benefits are hindered by long-term water deficit, which results in different levels of impact on wood radial growth and density. Despite of the intensification of long-term water deficit, tree-ring width appears to benefit from the minimum temperature increase, whereas the effects of long-term droughts significantly prevail on tree-ring density. Our results further highlight the dependency of the species on deep water sources after the juvenile stage. The impact of climate changes on long-term droughts and their repercussion on the shallow groundwater table and P. pinaster’s vulnerability are also discussed. This work provides relevant information for forest management in the semi-arid area of the Alentejo region of Portugal. It should ease the elaboration of mitigation strategies to assure P. pinaster’s production capacity and quality in response to more arid conditions in the near future in the region.

Colorectal cancer and non-malignant respiratory disease in asbestos cement and cement workers

International Nuclear Information System (INIS)

Jacobsson, K.

1993-09-01

Radiologically visible parenchymal changes (small opacities >= 1/0;ILO 1980 classification) were present in 20% of a sample of workers (N=174), employed for 20 years (median) in an asbestos cement plant. Exposure-response relationships were found, after controlling for age and smoking habits. In a sample of asbestos cement workers with symptoms and signs suggestive of pulmonary disease (N=33), increased lung density measured by x-ray computed tomography, and reduced static lung volumes and lung compliance was found. In a cohort of asbestos cement workers (N=1.929) with an estimated median exposure of 1.2 fibres/ml, the mortality from non-malignant respiratory disease was increased in comparison to a regional reference cohort (N=1.233). A two-to three-fold increase of non-malignant respiratory mortality was noted among workers employed for more than a decade in the asbestos cement plant, compared to cement workers (N=1.526), who in their turn did not experience and increased risk compared to the general population. In the cohorts of asbestos cement and cement workers, there was a tow-to three-fold increased incidence of cancer in the right part of the colon, compared to the general population as well as to external reference cohorts of other industrial workers (N=3.965) and fishermen (N=8.092). A causal relation with the exposure to mineral dust and fibres was supported by the findings of higher risk estimated in subgroups with high cumulated asbestos doses or longer duration of cement work. The incidence of cancer in the left part of the colon was not increased. Morbidity data, but not mortality data, disclosed the subsite-specific risk pattern. Both asbestos cement workers and cement workers has an increased incidence of rectal cancer, compared with the general population, and with the fishermen. The risk was, however, of the same magnitude among the other industrial workers. 181 refs

A method to determine density in wood samples using attenuation of 59.5 KeV gamma radiation

International Nuclear Information System (INIS)

Dinator, M.I.; Morales, J.R.; Aliaga, N.; Karsulovic, J.T.; Sanchez, J.; Leon, L.A.

1996-01-01

A nondestructive method to determine the density of wood samples is presented. The photon mass attenuation coefficient in samples of Pino Radiata was measured at 59.5 KeV with a radioactive source of Am-241. The value of 0.192 ± 0.002 cm 2 /g was obtained with a gamma spectroscopy system and later used on the determination of the mass density in sixteen samples of the same species. Comparison of these results with those of gravimetric method through a linear regression showed a slope of 1.001 and correlation factor of 0.94. (author)

Pullout behavior of steel fibers from cement-based composites

DEFF Research Database (Denmark)

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

1997-01-01

A comprehensive experimental program on pullout tests of steel fibers from cement based matrices is described. A specially designed single fiber pullout apparatus was used to provide a quantitative determination of interfacial properties that are relevant to toughening brittle materials through...... fiber reinforcement. The parameters investigated included a specially designed high strength cement based matrix called Densified Small Particles system (DSP), a conventional mortar matrix, fiber embeddment length, and the fiber volume fraction. The mediums from which the fiber was pulled included...... fraction in the cement matrix increase the peak pullout load and the pullout work. (3) The major bond mechanism in both systems is frictional sliding. ...

Soda-Anthraquinone Durian (Durio Zibethinus Murr.) Rind Linerboard and Corrugated Medium Paper: A Preliminary Test

Science.gov (United States)

Rizal Masrol, Shaiful; Irwan Ibrahim, Mohd Halim; Adnan, Sharmiza; Mubarak Sa'adon, Amir; Ika Sukarno, Khairil; Fadrol Hisham Yusoff, Mohd

2017-08-01

A preliminary test was conducted to investigate the characteristics of linerboard and corrugated medium paper made from durian rind waste. Naturally dried durian rinds were pulped according to Soda-Anthraquinone (Soda-AQ) pulping process with a condition of 20% active alkali, 0.1% AQ, 7:1 liquor to material ratio, 120 minutes cooking time and 170°C cooking temperature. The linerboard and corrugated medium paper with a basis weight of 120 gsm were prepared and evaluated according to Malaysian International Organization for Standardization (MS ISO) and Technical Association of the Pulp and Paper Industry (TAPPI). The results indicate that the characteristics of durian rind linerboard are comparable with other wood or non-wood based paper and current commercial paper. However, low CMT value for corrugated medium and water absorptiveness quality for linerboard could be improved in future. Based on the bulk density (0.672 g/cm3), burst index (3.12 kPa.m2/g) and RCT (2.00 N.m2/g), the durian rind has shown a good potential and suitable as an alternative raw material source for linerboard industry.

Hospital waste ashes in Portland cement mortars

International Nuclear Information System (INIS)

Genazzini, C.; Zerbino, R.; Ronco, A.; Batic, O.; Giaccio, G.

2003-01-01

Nowadays, most concretes incorporate mineral additions such as pozzolans, fly ash, silica fume, blast furnace slag, and calcareous filler among others. Although the technological and economical benefits were the main reasons for the use of mineral additions, the prevention of environmental contamination by means of proper waste disposal becomes a priority. The chance of incorporating hospital waste ashes in Portland cement-based materials is presented here. Ash characterization was performed by chemical analysis, X-ray diffraction, radioactive material detection, and fineness and density tests. Conduction calorimetry and setting time tests were developed on pastes including ash contents from 0% to 100%. Mortars were prepared including ash contents up to 50% of cement. The results of setting time, temperature development, flexural and compressive strengths, water absorption, density, and leachability are analyzed. Results indicate that Portland cement systems could become an alternative for the disposal of this type of ashes

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.

Implementation of recycled cellulosic fibres into cement based composites and testing their influence on resulting properties

Science.gov (United States)

Hospodarova, V.; Stevulova, N.; Vaclavik, V.; Dvorsky, T.

2017-10-01

Nowadays, the application of raw materials from renewable sources such as wood, plants and waste paper to building materials preparing has gained a significant interest in this research area. The aim of this paper is to investigate the impact of the selected plasticizer on properties of fibres composites made of cellulosic fibres coming from recycled waste paper and cement. Investigations were performed on specimens with 0.5 wt. % of fibre addition without and with plasticizer. A comparative study did not show positive influence of plasticizer on the density and thermal conductivity of 28 days hardened composite. The specimens after 1, 3 and 7 days of hardening with plasticizer exhibited the highest impact on compressive strength in comparison to composite without plasticizer but 28 days hardened specimens reached the same value of strength characteristic (41 MPa).

An Analysis of the U.S. Wood Products Import Sector: Prospects for Tropical Wood Products Exporters

Directory of Open Access Journals (Sweden)

W.A.R.T.W. Bandara

2012-10-01

Full Text Available The U.S. has dramatically altered its wood product imports and exports during the past few years,and at present, it is the second largest wood product importer in the world. Hence, an understanding ofmarket structures, factors in selecting foreign suppliers, and the emphasis placed on environmentalissues/certification are critical to understand from the perspective of wood products importers in the U.S.This study provides an analysis of the U.S. wood products import sector with special emphasis on currentand future opportunities for tropical wood products exporters to the U.S. market.In this study, 158 wood products importers in the U.S. were surveyed using a mailingquestionnaire. The adjusted response rate was 40.6 percent. Results indicated that most of the respondentswere small to medium scale firms, but major importers of wood products. According to respondents,wood products to the U.S. mainly come from Brazil, Chile, and China. From the importers’ perspective,Brazilian wood products ranked first for its quality followed by wood products from Chile and Finland.Product quality, long term customer relationships, on-time delivery of orders, fair prices, and supplierreputation were the factors deemed important in selecting overseas suppliers. Majority of respondentswere importing certified wood products. FSC, SFI, and ISO 14000 were the mostly accepted certificationprograms. However, certification was not a major factor in foreign supplier selection criteria. Whenconsidered the U.S. wood products importers’ tendency to diversify their products and species imported,attractive opportunities exist for wood products suppliers from tropical countries.

Properties of cement based composites modified using diatomaceous earth

Science.gov (United States)

Pokorný, Jaroslav; Pavlíková, Milena; Záleská, Martina; Pavlík, Zbyšek

2017-07-01

Diatomite belongs among natural materials rich on amorphous silica (a-SiO2). When finely milled, it can potentially substitute part of cement binder and positively support formation of more dense composite structure. In this connection, two types of diatomaceous earth applied as a partial substitution of 5, 10, 15, and 20 mass% of Portland cement in the composition of cement paste were studied. In the tested mixtures with cement blends, the amount of batch water remained same, with water/binder ratio 0.5. For fresh paste mixtures, initial and final setting times were measured. First, hardened pastes cured 28 days in water were characterized by their physical properties such as bulk density, matrix density and open porosity. Then, their mechanical and thermophysical parameters were assessed. Obtained results gave clear evidence of setting time shortening for pastes with diatomite what brought negative effect with respect to the impaired workability of fresh mixtures. On the other hand, there was observed strength improvement for mixtures containing diatomite with higher amount of SiO2. Here, the increase in mechanical resistivity was distinct up to 15 mass% of cement replacement. Higher cement substitution by diatomite resulted in an increase in porosity and thus improvement of thermal insulation properties.

CALCIUM ORTHOPHOSPHATES HYDRATES: FORMATION, STABILITY AND INFLUENCE ON STANDARD PROPERTIES OF PORTLAND CEMENT

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Kaziliunas A.

2013-12-01

Full Text Available Preparation of phosphogypsum to produce the binders requires a much higher input than preparation of natural gypsum stone. This makes it uncompetitive material. The investigations presented therein are meant to reduce this input by looking for the ways of rendering impurities harmless. Soluble acid orthophosphates are the main harmful impurity of phosphogypsum. The studies show that dry insoluble calcium orthophosphates hydrates (1.09 % and 2.18 % P2O5 in gypsum have little effect on W/C, setting times and soundness of Portland cement pastes. Insoluble calcium orthophosphates hydrates {CaHPO4∙2H2O, Ca8(HPO42(PO44∙5H2O and Ca9(HPO4(PO45(OH∙4H2O} formed in acidic medium (pH = 4.2 - 5.9 have been destroyed in alkaline medium and reduce standard compressive strength of cement up to 28 %. Calcium orthophosphates hydrates of hydroxyapatite group are stable in alcaline medium, while in dry state they reduce the standard compressive strength of cement until 10 %, but their suspensions prolong setting times of Portland cement as soluble orthophosphates – 2 - 3 times. Alkalis in cement increase pH of paste, but do not change the process of formation of calcium orthophosphates hydrates of hydroxyapatite group: it takes place through an intermediate phase - CaHPO4·2H2O, whose transformation into apatite lasts for 2 - 3 months.

Nanoreinforced biocompatible hydrogels from wood hemicelluloses and cellulose whiskers

Science.gov (United States)

Muzaffer Ahmet Karaaslan; Mandla A. Tshabalala; Daniel J. Yelle; Gisela Buschle-Diller

2011-01-01

Nanoreinforced hydrogels with a unique network structure were prepared from wood cellulose whiskers coated with chemically modified wood hemicelluloses. The hemicelluloses were modified with 2-hydroxyethylmethacrylate prior to adsorption onto the cellulose whiskers in aqueous medium. Synthesis of the hydrogels was accomplished by in situ radical polymerization of the...

Immobilization and leaching mechanisms of radwaste in cement-based matrices

International Nuclear Information System (INIS)

Glasser, F.P.; Rahman, A.A.; Crawford, R.W.; McCullough, C.E.; Angus, M.J.

1982-03-01

The components of anhydrous cement clinkers and their adsorptive properties for Cs has been determined. The efficiency of different analytical methods are compared, and it is shown that only radiochemical methods afford a true picture of the quantitative extent of adsorption. Hydrothermal studies have been undertaken to assess the interactions between the Ca(OH) 2 component of cement and radioactive waste constituents. In most cases, chemical reaction occurs due to the strongly alkaline nature of the medium: the potential of hydrothermal methods for predicting the behaviour and performance of cement-radwaste systems is assessed and the relevant solution chemistry described. Cement-zeolite interactions have been studied: these interactions are revealed by a variety of physical techniques, and begin to afford some insight into the reaction mechanism. (author)

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.

Influence of energy density of different light sources on knoop hardness of a dual-cured resin cement

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Evandro Piva

2008-06-01

Full Text Available The purpose of this study was to evaluate the Knoop hardness of a dual-cured resin-based luting cement irradiated with different light sources as well energy density through a ceramic sample. Three light-curing unit (LCUs were tested: tungsten halogen light (HAL, light-emitting diode (LED and xenon plasma-arc (PAC lamp. Disc-shaped specimens were fabricated from a resin-based cement (Enforce. Three energy doses were used by modifying the irradiance (I of each LCU and the irradiation time (T: 24 Jcm-2 (I/2x2T, 24 Jcm-2 (IxT and 48 Jcm-2 (Ix2T. Energy doses were applied through a 2.0-mm-thick ceramic sample (Duceram Plus. Three groups underwent direct irradiation over the resin cement with the different LCUs and a chemically-activated group served as a control. Thirteen groups were tested (n=10. Knoop hardness number (KHN means were obtained from cross-sectional areas. Two-way ANOVA and the Holm-Sidak method were used for statistical comparisons of activation mode and energy doses (a=5%. Application of 48 J.cm-2 energy dose through the ceramic using LED (50.5±2.8 and HAL (50.9±3.7 produced significantly higher KHN means (p<0.05 than the control (44.7±3.8. LED showed statistically similar performance to HAL. Only HAL showed a relationship between the increase of LCU energy dose and hardness increase.

Influence of energy density of different light sources on Knoop hardness of a dual-cured resin cement.

Science.gov (United States)

Piva, Evandro; Correr-Sobrinho, Lourenço; Sinhoreti, Mario Alexandre Coelho; Consani, Simonides; Demarco, Flávio Fernando; Powers, John Michael

2008-01-01

The purpose of this study was to evaluate the Knoop hardness of a dual-cured resin-based luting cement irradiated with different light sources as well energy density through a ceramic sample. Three light-curing unit (LCUs) were tested: tungsten halogen light (HAL), light-emitting diode (LED) and xenon plasma-arc (PAC) lamp. Disc-shaped specimens were fabricated from a resin-based cement (Enforce). Three energy doses were used by modifying the irradiance (I) of each LCU and the irradiation time (T): 24 Jcm(-2) (I/2x2T), 24 Jcm(-2) (IxT) and 48 Jcm(-2) (Ix2T). Energy doses were applied through a 2.0-mm-thick ceramic sample (Duceram Plus). Three groups underwent direct irradiation over the resin cement with the different LCUs and a chemically-activated group served as a control. Thirteen groups were tested (n=10). Knoop hardness number (KHN) means were obtained from cross-sectional areas. Two-way ANOVA and the Holm-Sidak method were used for statistical comparisons of activation mode and energy doses (alpha=5%). Application of 48 J.cm(-2) energy dose through the ceramic using LED (50.5+/-2.8) and HAL (50.9+/-3.7) produced significantly higher KHN means (p<0.05) than the control (44.7+/-3.8). LED showed statistically similar performance to HAL. Only HAL showed a relationship between the increase of LCU energy dose and hardness increase.

Compatibility improvement method of empty fruit bunch fibre as a replacement material in cement bonded boards: A review

Science.gov (United States)

Dullah, Hayana; Abidin Akasah, Zainal; Zaini Nik Soh, Nik Mohd; Mangi, Sajjad Ali

2017-11-01

The utilization of oil palm empty fruit bunch (OPEFB) fibre on bio-composite product has been introduced to replace current material mainly wood fibre. OPEFB is widely available as palm oil is one of the major agricultural crops in Malaysia. EFB fibre are lignocellulosic materials that could replace other natural fibre product especially cement bonded board. However, the contains of residual oil and sugar in EFB fibre has been detected to be the reason for incompatibility issue between EFB fibre and cement mixtures. Regarding on the issue, a study has been conducted widely on finding the suitable pre-treatment method for EFB fibre to remove carbohydrate contained in the said fibre that are known to inhibit cement hydration. Aside from that, cement accelerator was introduced to enhance the hydration of cement when it was mixed with natural fibre. Hence, this paper will summaries the previous findings and in-depth study on the use of EFB fibre as a replacement material in cement bonded fibre boards.

Glycerol Salicylate-based Pulp-Capping Material Containing Portland Cement.

Science.gov (United States)

Portella, Fernando Freitas; Collares, Fabrício Mezzomo; Santos, Paula Dapper; Sartori, Cláudia; Wegner, Everton; Leitune, Vicente Castelo Branco; Samuel, Susana Maria Werner

2015-01-01

The purpose of this study was to evaluate the water sorption, solubility, pH and ability to diffuse into dentin of a glycerol salicylate-based, pulp-capping cement in comparison to a conventional calcium hydroxide-based pulp capping material (Hydcal). An experimental cement was developed containing 60% glycerol salicylate resin, 10% methyl salicylate, 25% calcium hydroxide and 5% Portland cement. Water sorption and solubility were determined based on mass changes in the samples before and after the immersion in distilled water for 7 days. Material discs were stored in distilled water for 24 h, 7 days and 28 days, and a digital pHmeter was used to measure the pH of water. The cement's ability to diffuse into bovine dentin was assessed by Raman spectroscopy. The glycerol salicylate-based cement presented higher water sorption and lower solubility than Hydcal. The pH of water used to store the samples increased for both cements, reaching 12.59 ± 0.06 and 12.54 ± 0.05 after 7 days, for Hydcal and glycerol salicylate-based cements, respectively. Both cements were able to turn alkaline the medium at 24 h and sustain its alkalinity after 28 days. Hydcal exhibited an intense diffusion into dentin up to 40 µm deep, and the glycerol salicylate-based cement penetrated 20 µm. The experimental glycerol salicylate-based cement presents good sorption, solubility, ability to alkalize the surrounding tissues and diffusion into dentin to be used as pulp capping material.

Selected mechanical properties of modified beech wood

Directory of Open Access Journals (Sweden)

Jiří Holan

2008-01-01

Full Text Available This thesis deals with an examination of mechanical properties of ammonia treated beach wood with a trademark Lignamon. For determination mechanical properties were used procedures especially based on ČSN. From the results is noticeable increased density of wood by 22% in comparison with untreated beach wood, which makes considerable increase of the most mechanical wood properties. Considering failure strength was raised by 32% and modulus of elasticity was raised at average about 46%.

Collision density approach of radiation damage in a multispecies medium

International Nuclear Information System (INIS)

Lux, I.; Pazsit, I.

1981-01-01

Space-energy dependent forward type equations for the collision densities of energetic atoms in a multispecies semi-infinite homogeneous medium are formulated. Introduction of the one-dimensional isotropic forward-backward model of Fermi for the scattering and application of the Laplace transform with respect to the lethargy variable will lead to a linear differential equation system with constant coefficients. This equation system is solved for an arbitrary number of species and relations between the collision densities and defect distributions of the different species are given in the Kinchin-Pease model of radiation damage. The case of an alien particle incident on a two-component target is examined in some detail and the sputtering spectra for the three species are given numerically. (author)

Collision density approach of radiation damage in a multispecies medium

Energy Technology Data Exchange (ETDEWEB)

Lux, I; Pazsit, I [Koezponti Elelmiszeripari Kutato Intezet, Budapest (Hungary)

1981-01-01

Space-energy dependent forward type equations for the collision densities of energetic atoms in a multispecies semi-infinite homogeneous medium are formulated. Introduction of the one-dimensional isotropic forward-backward model of Fermi for the scattering and application of the Laplace transform with respect to the lethargy variable will lead to a linear differential equation system with constant coefficients. This equation system is solved for an arbitrary number of species and relations between the collision densities and defect distributions of the different species are given in the Kinchin-Pease model of radiation damage. The case of an alien particle incident on a two-component target is examined in some detail and the sputtering spectra for the three species are given numerically.

Wood ash used as partly sand and/or cement replacement in mortar

DEFF Research Database (Denmark)

Ottosen, Lisbeth M.; Hansen, Esben Østergaard; Jensen, Pernille Erland

2016-01-01

, and the present work reports a characterization of three different WAs. Properties of mortar samples with the WAs used as partly cement and/or sand replacement are reported. Compressive strength development and porosity are the mortar properties in focus. The overall aim of the work is to evaluate the influence...... of the ashes were dry and sampled just after the incineration, whereas one ash had a water content of 15%, because the ash was sprayed with water to avoid dust during ash handling at the incineration plant. Regardless of replacing cement or sand with WAs, the compressive strength decreased compared...... to a reference without ash, however, the decrease was small for two of the ashes. Using the ash with the high LoI resulted in significantly lower compressive strength compared to the other two ashes. The mortar samples with two of the ashes (with low LoI) had qualities, which were very encouraging in order...

Prediction models of mechanical properties for pet-mortar composite in sodium sulphateaggressive mediums

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Kazi Tani Nabil

2018-01-01

Full Text Available In this research, an investigation was carried out on the effect of sodium sulphate attack on the durability of composites produced with waste polyethylene terephthalate (PET. Experiments were accomplished on limestone sand and cement mortars where the blended Portland cement was partially replaced by various volume fractions of waste PET particles (6%, 12% and 17%. The test solutions used to supply the sulphate ions and cations were 5%sodium sulphate solution. Compressive strengths measured on specimens were used to assess the changes in the mechanical properties of PET-mortars exposed to sulphate attack at different ages, mainly the Young modulus of elasticity. Based on experimental compressive tests on PETMortar composite specimens and there densities, the evolution of Young modulus of elasticity has been analyzed in accordance with normative models given by (ACI-318 and (BS-8110 codes of practice. In addition, a comparative study has been carried out for corrosion resistance coefficients K of unmodified mortar to those modified with waste PET particles. It can be noticed that, for the composite immersed in a corrosive Na2SO4 solution, the corrosion resistance coefficients decrease with the increase of the immersion period. The corrosion sulphate resistance K based on Young modulus before and after immersion of PET-mortar composites is better than that of the control mortar. Therefore, for safety considerations of PET-mortar composites use, ACI 318 is recommended code for design and investigation works. Also, it can be concluded that adding waste PET by volume fractions (6%, 12% and 17% to blend Portland cement renders this cement more resistant to the sodium sulphate aggressive medium. Therefore, composites materials based waste PET aare often presented as the materials of the future because of their potential for innovation and the advantages they offer. In fact, using waste PET as cement substitutes reduces the energy consumption. These

Caracterização da estrutura anatômica, densidade básica e morfologia de cavacos da madeira de Eucalyptus grandis para a produção de painéis MDF Characterization of wood anatomy, basic density, and morphology of Eucalyptus grandis chips for MDF production

Directory of Open Access Journals (Sweden)

Ugo Leandro Belini

2008-08-01

Full Text Available O aumento na produção dos painéis "Medium Density Fiberboard" (MDF confeccionados com madeira de espécies de Eucalyptus spp de rápido crescimento evidencia a necessidade da caracterização dos seus componentes celulares, da densidade básica e da morfologia de cavacos. Com esse objetivo, foram coletadas três amostras de cavacos de madeira de árvores de Eucalyptus grandis, na linha de produção de indústria de painel. Em laboratório, os cavacos foram dissociados por maceração, para a avaliação das dimensões das fibras e dos vasos; determinou-se a densidade básica dos cavacos, bem como se caracterizaram a sua espessura e morfologia. Os resultados indicaram valores médios de 1005-19,7-11,8-3,9 µm para o comprimento, largura, diâmetro do lume e espessura média da parede das fibras, respectivamente. A densidade básica da madeira foi de 0,432 g/cm³ e a espessura dos cavacos, de 4,36 mm. Os valores médios de retenção dos cavacos foram de 0,9-16,9-44,5-30,7-6,1-0,9% nas peneiras 40, 25, 16, 8, 3,35 mm e fundo, respectivamente, sendo 75,2% retidos nas peneiras de 16-8 mm de abertura. Os resultados das análises anatômicas e morfológicas dos cavacos de madeira foram discutidos e comparados com informações da literatura especializada e correlacionados com o processo produtivo de chapas MDF.The increase of the MDF panels (Medium Density Fiberboard production by the use of the fast growing eucalypt wood species it evidences the need of the characterization of the cellular components, basic density and the chips morphology. With this aim 3 samples of wood chips of Eucalyptus grandis trees were collected, in the production line of panel industry. In laboratory, the wood chips were dissociated by maceration for the evaluation of the fiber and vessels dimensions; the wood basic density was determined and the thickness and morphology were characterized. The results indicated mean values of 1005-19,7-11,8-3,9 µm for the fiber length

Mechanical Properties and Durability of CNT Cement Composites

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María del Carmen Camacho

2014-02-01

Full Text Available In the present paper, changes in mechanical properties of Portland cement-based mortars due to the addition of carbon nanotubes (CNT and corrosion of embedded steel rebars in CNT cement pastes are reported. Bending strength, compression strength, porosity and density of mortars were determined and related to the CNT dosages. CNT cement paste specimens were exposed to carbonation and chloride attacks, and results on steel corrosion rate tests were related to CNT dosages. The increase in CNT content implies no significant variations of mechanical properties but higher steel corrosion intensities were observed.

Improvements in processing characteristics and engineering properties of wood flour-filled high density polyethylene composite sheeting in the presence of hollow glass microspheres

Science.gov (United States)

Baris Yalcin; Steve E Amos; Andrew S D Souza; Craig M Clemons; I Sedat Gunes; Troy K Ista

2012-01-01

Hollow glass microspheres were introduced into wood flour/high density polyethylene composites by melt compounding in a twin-screw extruder. The prepared composites were subsequently converted to extruded profiles in order to obtain composite sheeting. The presence of hollow glass microspheres highly reduced the density of the extruded sheets down to 0.9 g/cc, while...

Application of RBF neural network improved by peak density function in intelligent color matching of wood dyeing

International Nuclear Information System (INIS)

Guan, Xuemei; Zhu, Yuren; Song, Wenlong

2016-01-01

According to the characteristics of wood dyeing, we propose a predictive model of pigment formula for wood dyeing based on Radial Basis Function (RBF) neural network. In practical application, however, it is found that the number of neurons in the hidden layer of RBF neural network is difficult to determine. In general, we need to test several times according to experience and prior knowledge, which is lack of a strict design procedure on theoretical basis. And we also don’t know whether the RBF neural network is convergent. This paper proposes a peak density function to determine the number of neurons in the hidden layer. In contrast to existing approaches, the centers and the widths of the radial basis function are initialized by extracting the features of samples. So the uncertainty caused by random number when initializing the training parameters and the topology of RBF neural network is eliminated. The average relative error of the original RBF neural network is 1.55% in 158 epochs. However, the average relative error of the RBF neural network which is improved by peak density function is only 0.62% in 50 epochs. Therefore, the convergence rate and approximation precision of the RBF neural network are improved significantly.

Incorporation of waste and fiber kaolin caroa panels in Medium Density Fiberboard - MDF; Incorporacao de residuos de caulim e fibras de caroa em paineis de media densidade- MDF

Energy Technology Data Exchange (ETDEWEB)

Bezerra, A.F.C.; Santana, L.N.L.; Neves, G.A.; Carvalho, L.H. de; Lopes, F.F.M., E-mail: anaflavia.dema@yahoo.com.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

2012-07-01

Medium-density panels are composites molded under high temperature and pressure which have physical and mechanical properties similar to those of solid wood. Their composition includes eucalyptus grandis fibers and pinus elliotii fibers, but other fibers can be used such as caroa fibers. The goal of this work was to manufacture panels which kaolin waste and caroa fibers and compare their physical, chemical and mechanical of these panels with a others. Both residue and the fibers were characterized by: differential thermal analysis, thermal gravimetric analysis and Xray diffraction. Through the process of pressing the test specimens were fabricated, test samples were evaluated by three point bending, internal bond, water absorption and swelling in thickness. The samples have low levels of thickness swelling, flexural strength and higher tensile and absorption content relative to commercial MDF. (author)

Predictive Modeling of Black Spruce (Picea mariana (Mill. B.S.P. Wood Density Using Stand Structure Variables Derived from Airborne LiDAR Data in Boreal Forests of Ontario

Directory of Open Access Journals (Sweden)

Bharat Pokharel

2016-12-01

Full Text Available Our objective was to model the average wood density in black spruce trees in representative stands across a boreal forest landscape based on relationships with predictor variables extracted from airborne light detection and ranging (LiDAR point cloud data. Increment core samples were collected from dominant or co-dominant black spruce trees in a network of 400 m2 plots distributed among forest stands representing the full range of species composition and stand development across a 1,231,707 ha forest management unit in northeastern Ontario, Canada. Wood quality data were generated from optical microscopy, image analysis, X-ray densitometry and diffractometry as employed in SilviScan™. Each increment core was associated with a set of field measurements at the plot level as well as a suite of LiDAR-derived variables calculated on a 20 × 20 m raster from a wall-to-wall coverage at a resolution of ~1 point m−2. We used a multiple linear regression approach to identify important predictor variables and describe relationships between stand structure and wood density for average black spruce trees in the stands we observed. A hierarchical classification model was then fitted using random forests to make spatial predictions of mean wood density for average trees in black spruce stands. The model explained 39 percent of the variance in the response variable, with an estimated root mean square error of 38.8 (kg·m−3. Among the predictor variables, P20 (second decile LiDAR height in m and quadratic mean diameter were most important. Other predictors describing canopy depth and cover were of secondary importance and differed according to the modeling approach. LiDAR-derived variables appear to capture differences in stand structure that reflect different constraints on growth rates, determining the proportion of thin-walled earlywood cells in black spruce stems, and ultimately influencing the pattern of variation in important wood quality attributes

Cytotoxicity Comparison of Harvard Zinc Phosphate Cement Versus Panavia F2 and Rely X Plus Resin Cements on Rat L929-fibroblasts.

Science.gov (United States)

Mahasti, Sahabi; Sattari, Mandana; Romoozi, Elham; Akbar-Zadeh Baghban, Alireza

2011-01-01

Resin cements, regardless of their biocompatibility, have been widely used in restorative dentistry during the recent years. These cements contain hydroxy ethyl methacrylate (HEMA) molecules which are claimed to penetrate into dentinal tubules and may affect dental pulp. Since tooth preparation for metal ceramic restorations involves a large surface of the tooth, cytotoxicity of these cements would be more important in fixed prosthodontic treatments. The purpose of this study was to compare the cytotoxicity of two resin cements (Panavia F2 and Rely X Plus) versus zinc phosphate cement (Harvard) using rat L929-fibroblasts in vitro. In this experimental study, ninety hollow glass cylinders (internal diameter 5-mm, height 2-mm) were made and divided into three groups. Each group was filled with one of three experimental cements; Harvard Zinc Phosphate cement, Panavia F2 resin cement and Rely X Plus resin cement. L929- Fibroblast were passaged and subsequently cultured in 6-well plates of 5×10(5) cells each. The culture medium was RPMI_ 1640. All samples were incubated in CO2. Using enzyme-linked immune-sorbent assay (ELISA) and (3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) (MTT) assay, the cytotoxicity of the cements was investigated at 1 hour, 24 hours and one week post exposure. Statistical analyses were performed via two-way ANOVA and honestly significant difference (HSD) Tukey tests. This study revealed significant differences between the three cements at the different time intervals. Harvard cement displayed the greatest cytotoxicity at all three intervals. After 1 hour Panavia F2 showed the next greatest cytotoxicity, but after 24-hours and oneweek intervals Rely X Plus showed the next greatest cytotoxicity. The results further showed that cytotoxicity decreased significantly in the Panavia F2 group with time (pHarvard cement group failed to showed no noticeable change in cytotoxicity with time. Although this study has limitations, it provides

Calcium carbonate-calcium phosphate mixed cement compositions for bone reconstruction.

Science.gov (United States)

Combes, C; Bareille, R; Rey, C

2006-11-01

The feasibility of making calcium carbonate-calcium phosphate (CaCO(3)-CaP) mixed cements, comprising at least 40% (w/w) CaCO(3) in the dry powder ingredients, has been demonstrated. Several original cement compositions were obtained by mixing metastable crystalline CaCO(3) phases with metastable amorphous or crystalline CaP powders in aqueous medium. The cements set within at most 1 h at 37 degrees C in atmosphere saturated with water. The hardened cement is microporous and exhibits weak compressive strength. The setting reaction appeared to be essentially related to the formation of a highly carbonated nanocrystalline apatite phase by reaction of the metastable CaP phase with part or almost all of the metastable CaCO(3) phase. The recrystallization of metastable CaP varieties led to a final cement consisting of a highly carbonated poorly crystalline apatite analogous to bone mineral associated with various amounts of vaterite and/or aragonite. The presence of controlled amounts of CaCO(3) with a higher solubility than that of the apatite formed in the well-developed CaP cements might be of interest to increase resorption rates in biomedical cement and favors its replacement by bone tissue. Cytotoxicity testing revealed excellent cytocompatibility of CaCO(3)-CaP mixed cement compositions.

Energy from wood biomass: The experience of the Brazilian forest sector

Energy Technology Data Exchange (ETDEWEB)

Couto, L. [Universidade Federal de Vicosa (Brazil); Graca, L.R. [Centro Nacional de Pesquisa de Floresta, Colombo (Brazil); Betters, D.R. [Colorado State Univ., Fort Collins, CO (United States)

1993-12-31

Wood biomass is one of the most significant renewable sources of energy in Brazil. Fuelwood and charcoal play a very important role not only for household energy consumption but also for the cement, iron and steel industries. Wood is used as an energy source by the pulp and paper, composite board and other industries of the country, mainly for steam and electricity generation. Ethanol, lignin-based coke and methanol from wood were produced at experimental units in Brazil but were not implemented on a commercial scale. Currently, a new experimental plant using a technology developed in the US is being built in the state of Bahia to generate electricity from Eucalyptus. This technology is a Biomass Integrated Gasification/Gas Turbine process which is expected to make the use of wood biomass economically feasible for electricity generation. Forest plantations are the main source of wood biomass for energy consumption by the Brazilian industrial sector. Fiscal incentives in the 1960s helped the country to begin a massive reforestation program mainly using Eucalyptus and Pinus species. A native species, bracatinga (Mimosa scabrella) has also been used extensively for wood energy plantations in southern Brazil. Technical, economic, social and environmental impacts of these plantation forests are discussed along with a forecast of the future wood energy utilization in Brazil.

Effect of moisture availability on wood density and vessel characteristics of Eucalyptus grandis in the warm temperate region of South Africa

CSIR Research Space (South Africa)

Naidoo, Sasha

2006-09-01

Full Text Available intolerant of adverse conditions, and performs poorly when planted on shallow soils and/or on dry sites. A study was conducted to assess the effect of moisture availability on the wood density and vessel characteristics of E. grandis grown in the warm...

Observed relationships between wood density and solution uptake during pressure treatment

Science.gov (United States)

Steve Halverson; Stan Lebow

2011-01-01

A better understanding of the relationship between wood properties and solution uptake during pressure treatment could lead to improvements in treatment quality and more efficient use of preservatives. In this study several years of treatment data representing a range of wood species, charge conditions and preservative formulations were analyzed to evaluate the...

PHYSICAL ANALYSIS OF QUALITY WOOD Melia azedarach

Directory of Open Access Journals (Sweden)

T. J. da Silva

2016-07-01

Full Text Available Forest species, in general, present a slow growth, which results and profits can manifest themselves in the long run, it becomes necessary the study and discovery of new species that may provide raw materials and return on invested capital more immediate, being that the Melia azedarach wood is a potential option. In the absence of information about, the objective of this paper is to determine its physical properties: basic density and shrinkage of the Melia azedarach species in the Itapeva-SP region. The data obtained in this study allow to classify wood Melia azedarach as wood of average density and good dimensional stability. Feature that makes it ideal for its use in furniture industry. The low amount of research related to quality of this wood prevents the commercial use of it to achieve its full potential harnessing its effectively, and essential investments in this field.

Pore structure in blended cement pastes

DEFF Research Database (Denmark)

Canut, Mariana Moreira Cavalcanti

Supplementary cementitious materials (SCMs), such as slag and fly ash, are increasingly used as a substitute for Portland cement in the interests of improvement of engineering properties and sustainability of concrete. According to studies improvement of engineering properties can be explained by...... on assumptions of degree of reaction and product densities gave for plain cement pastes results comparable to MIP data.......Supplementary cementitious materials (SCMs), such as slag and fly ash, are increasingly used as a substitute for Portland cement in the interests of improvement of engineering properties and sustainability of concrete. According to studies improvement of engineering properties can be explained...... supplement each other. Cement pastes (w/b=0.4) with and without slag and fly ash cured at two moisture (sealed and saturated) and temperature (20 and 55ºC) conditions were used to investigate the combined impact of SCMs addition and curing on the pore structure of pastes cured up to two years. Also...

Medium-Density Mixed Housing: sustainable design and construction of South African social housing

CSIR Research Space (South Africa)

Osman, A

2010-09-01

Full Text Available Medium-Density Mixed Housing (MDMH), of which social housing (SH) is one component, is perceived to have the capacity to contribute to the transformation of fragmented South African cities more than the massive roll-out of government subsidised ‘one-house...

Bulk density calculations from prompt gamma ray yield

International Nuclear Information System (INIS)

Naqvi, A.A.; Nagadi, M.M.; Al-Amoudi, O.S.B.; Maslehuddin, M.

2006-01-01

Full text: The gamma ray yield from a Prompt Gamma ray Neutron Activation Analysis (PGNAA) setup is a linear function of element concentration and neutron flux in a the sample with constant bulk density. If the sample bulk density varies as well, then the element concentration and the neutron flux has a nonlinear correlation with the gamma ray yield [1]. The measurement of gamma ray yield non-linearity from samples and a standard can be used to estimate the bulk density of the samples. In this study the prompt gamma ray yield from Blast Furnace Slag, Fly Ash, Silica Fumes and Superpozz cements samples have been measured as a function of their calcium and silicon concentration using KFUPM accelerator-based PGNAA setup [2]. Due to different bulk densities of the blended cement samples, the measured gamma ray yields have nonlinear correlation with calcium and silicon concentration of the samples. The non-linearity in the yield was observed to increase with gamma rays energy and element concentration. The bulk densities of the cement samples were calculated from ratio of gamma ray yield from blended cement and that from a Portland cement standard. The calculated bulk densities have good agreement with the published data. The result of this study will be presented

Collision density approach of radiation damage in a multi-species medium

International Nuclear Information System (INIS)

Lux, I.; Pazsit, I.

1981-05-01

Space-energy dependent foward type equations for the collision densities of energetic atoms in multi-species semi-infinite homogeneous medium are formulated. The introduction of the one-dimensional isotropic forward-backward model of Fermi for the scattering and application of the Laplace transformation with respect to the lethargy variable leads to a linear differential equation system with constant coefficients. This equation system is solved for an arbitrary number of species and relations between the collision densities and defect distributions of the different species are given in the Kinchin Pease model. The case of an alien particle incident on a two-component target is examined in some detail and the sputtering spectra are given numerically. (author)

Effect of explant density and medium culture volumes on cassava micropropagation in Temporal Immersion System

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Milagros Basail

2003-04-01

Full Text Available Due to the need of producing high quality planting material available to cassava growers, it has been necessary to look for alternatives in order to increase the efficiancy of in vitro propagation methods and their automation, such as the use of the Temporal Immersion Systems (RITA®. This work was carried out to increase the multiplication coefficient for cassava mass propagation through out Temporal Immersion Systems. The clone ‘CMC-40’ was used. Different medium volumes per explant, and material density per unit at a given Immersion frequency were tested. The highest results were obtained in the 2.8 multiplication coefficient with 20 ml culture medium volume and 3.2 using a density of 40 explants/flask. When the Temporal Immersion System is used with these results, a more efficient method for cassava micropropagation is established and also higher quality vitroplants for the rooting stage and further acclimatization in field conditions are produced. Key Words: Tissue Culture, liquid culture medium, Manihot esculenta Crantz

Panel and planar experimental shear behavior of wood panels ...

African Journals Online (AJOL)

Panel shear strength along the thickness and planar shear along the length of wood panels laminated softwood oriented OSB 10 mm thick, conditioned at different moisture contents (anhydrous medium, ambient temperature and humid medium) was measured on standardized test specimens, cut in half lengthwise panel ...

[Effects of surface roughness of bone cements on histological characteristics of induced membranes].

Science.gov (United States)

Liu, Hai-Xiao; Xu, Hua-Zi; Zhang, Yu; Hu, Gang; Shen, Yue; Cheng, Xiao-Jie; Peng, Lei

2012-08-01

To explore surface roughness of bone cement and surround tissue on histological characteristic of induced membranes. Bone cements with smooth and rough surface were implanted in radius bone defect, intramuscular and subcutaneous sites of rabbits, and formed induced membranes. Membranes were obtained and stained (HE) 6 weeks later. Images of membrane tissue were obtained and analyzed with an automated image analysis system. Five histological parameters of membranes were measured with thickness,area,cell density,ECM density and microvessel density. Double factor variance analysis was used to evaluate the effect of the two factors on histological characteristics of induced membranes. Membranes can be induced by each kind of bone cement and at all the three tissue sites. In histological parameters of thickness,area and micro vessel,there were significant differences among the membranes induced at different tissue sites (P = 0.000, P = 0.000, P = 0.000); whereas, there were no significant differences in histological parameters of cell density and ECM density (P = 0.734, P = 0.638). In all five histological parameters of membranes, there were no significant differences between the membranes induced by bone cements with different surface roughness (P = 0.506, P = 0.185, P = 0.883, P = 0.093, P = 0.918). Surround tissue rather than surface roughness of bone cements can affect the histological characteristics of induced membranes. The fibrocystic number, vascularity, mechanical tension and micro motion of the surround tissue may be closely correlated with the histological characteristics of induced membranes.

Effects of Boron Compounds on the Mechanical and Fire Properties of Wood-chitosan and High-density Polyethylene Composites

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Guo-Fu Wu

2014-05-01

Full Text Available Wood-plastic composites (WPCs represent a growing class of durable, low-maintenance construction materials whose use can decrease dependence on petroleum. High-density polyethylene (HDPE, chitosan (CS, wood flour (WF, boric acid (BA, and borax (BX, as well as maleic anhydride grafted polyethylene (MAPE and polyethylene wax (PE wax, were used to develop a durable wood-plastic composite (WPC using the extrusion method. The effects of boron compounds (3%, 6%, 9%, or 12% by weight BA/BX on the mechanical and fire properties of the WPCs were investigated. Mechanical testing indicated that as the percentage weight of boron compounds increased, the flexural modulus, flexural strength, and tensile strength significantly decreased. Cone calorimeter tests were used to characterize the fire performance of the WPCs, and these results suggested that adding BA/BX compounds to WPCs modestly improved the fire performance. As the percentage weight of BA/BX increased from 3% to 9%, the time to ignition (TTI, heat release rate (HRR, total heat release rate (HRR-Total, smoke production rate (SPR, and specific extinction area (SEA of the WPCs were all reduced.

EFFECT OF CHEMICAL MODIFICATION AND HOT-PRESS DRYING ON POPLAR WOOD

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Guo-Feng Wu

2010-11-01

Full Text Available Urea-formaldehyde prepolymer and hot-press drying were used to improve the properties of poplar wood. The wood was impregnated with the prepolymer using a pulse-dipping machine. The impregnated timbers were compressed and dried by a multilayer hot-press drying kiln. The drying rate was more rapid during the chemical modification and hot-press drying than conventional kiln-drying. In addition, the properties of timber were also enhanced obviously. When the compression rate was 28.6%, the basic density, oven dry density and air-dried density of modified wood improved 22%, 71%, and 70%, respectively. The bending strength and compressive strength parallel to grain increased 60% and 40%. The water uptake of treated wood was significantly decreased compared with the untreated wood. The FTIR analysis successfully showed that the intensity of hydroxyl and carbonyl absorption peaks decreased significantly, which was attributed to a reaction of the NHCH2OH of urea-formaldehyde prepolymer with the wood carboxyl (C=O and hydroxyl (-OH groups. The XRD results indicated that the degree of crystallinity increased from 35.09% to 36.91%. The morphologic models of chemical within wood were discovered by SEM.

Growth and Wood/Bark Properties of Abies faxoniana Seedlings as Affected by Elevated CO2

Institute of Scientific and Technical Information of China (English)

Yun-Zhou Qiao; Yuan-Bin Zhang; Kai-Yun Wang; Qian Wang; Qi-Zhuo Tian

2008-01-01

Growth and wood and bark properties of Abies faxoniana seedlings after one year's exposure to elevated CO2 concentration (ambient + 350 (=1= 25) μmol/mol) under two planting densities (28 or 84 plants/mz) were investigated in closed-top chambers. Tree height, stem diameter and cross-sectional area, and total biomass were enhanced under elevated CO2 concentration, and reduced under high planting density. Most traits of stem bark were improved under elevated CO2 concentration and reduced under high planting density. Stem wood production was significantly increased in volume under elevated CO2 concentration under both densities, and the stem wood density decreased under elevated CO2 concentration and increased under high planting density. These results suggest that the response of stem wood and bark to elevated CO2 concentration is density dependent. This may be of great importance in a future CO2 enriched world in natural forests where plant density varies considerably. The results also show that the bark/wood ratio in diameter, stem cross-sectional area and dry weight are not proportionally affected by elevated CO2 concentration under the two contrasting planting densities. This indicates that the response magnitude of stem bark and stem wood to elevated CO2 concentration are different but their response directions are the same.

Study of commercial chemical additives for cementation of radioactive waste

International Nuclear Information System (INIS)

Mota Vieira, V.; Oliveira, C.C. de

2015-01-01

In this research it has been studied the effects of chemical additives (admixtures) in the cementation process of radioactive wastes, which are used to improve the properties of waste cementation process, both of the paste and of the solidified product. However there are a large variety of these materials that are frequently changed or taken out of the market, then it is essential to know the commercially available materials and their effects. The tests were carried out with a solution simulating the evaporator concentrate waste coming from PWR nuclear reactors. It was cemented using two formulations, A and B, incorporating higher or lower amount of waste, respectively. It was added chemical admixtures from two manufacturers (S and H), which were: accelerators, set retarders and superplasticizers. The experiments were organized by a factorial design 23. The measured parameters were the viscosity, the setting time, the paste and product density and the compressive strength. In this study we performed comparative analyzes of the results of compressive strength at age of 28 and 90 days and between the densities of the samples at the same ages. The compressive strength test at age of 28 days is considered a parameter essential issues related to security handling, transport and storage of cemented waste product. The results showed that the addition of accelerators improved the compressive strength of the cemented product, but presented lower values density products. (authors)

Bacterial Community Succession in Pine-Wood Decomposition.

Science.gov (United States)

Kielak, Anna M; Scheublin, Tanja R; Mendes, Lucas W; van Veen, Johannes A; Kuramae, Eiko E

2016-01-01

Though bacteria and fungi are common inhabitants of decaying wood, little is known about the relationship between bacterial and fungal community dynamics during natural wood decay. Based on previous studies involving inoculated wood blocks, strong fungal selection on bacteria abundance and community composition was expected to occur during natural wood decay. Here, we focused on bacterial and fungal community compositions in pine wood samples collected from dead trees in different stages of decomposition. We showed that bacterial communities undergo less drastic changes than fungal communities during wood decay. Furthermore, we found that bacterial community assembly was a stochastic process at initial stage of wood decay and became more deterministic in later stages, likely due to environmental factors. Moreover, composition of bacterial communities did not respond to the changes in the major fungal species present in the wood but rather to the stage of decay reflected by the wood density. We concluded that the shifts in the bacterial communities were a result of the changes in wood properties during decomposition and largely independent of the composition of the wood-decaying fungal communities.

Comparative evaluation of antimicrobial activity of three cements: new endodontic cement (NEC), mineral trioxide aggregate (MTA) and Portland.

Science.gov (United States)

Hasan Zarrabi, Mohammad; Javidi, Maryam; Naderinasab, Mahboube; Gharechahi, Maryam

2009-09-01

Using the agar diffusion method, we conducted an in vitro study to evaluate the antimicrobial activity of mineral trioxide aggregate (MTA), new endodontic cement (NEC) and Portland cement at different concentrations against five different microorganisms. A base layer was made using Muller-Hinton agar for Escherichia coli (ATCC 10538) and Candida (ATCC 10231). For Actinomyces viscosus (ATCC 15987), Enterococcus faecalis (ATCC 10541) and Streptococcus mutans (ATCC 25175) blood agar medium was used. Wells were formed by removing the agar, and the materials were placed in the well immediately after manipulation. The plates were kept at room temperature for 2 h for prediffusion, and then incubated at 37 degrees C for 72 h. The inhibition zones were then measured. The data were analyzed using ANOVA and the Tukey test to compare the differences among the three cements at different concentrations. The positive controls showed bacterial growth, while the negative controls showed no bacterial growth. All materials showed antimicrobial activity against the tested strains except for Enterococcus faecalis. NEC created larger inhibition zones than MTA and Portland cement. This difference was significant for Portland cement (P 0.05). Among the examined microorganisms, the largest inhibition zone was observed for Actinomyces group (P < 0.05). The antimicrobial activity of the materials increased with time and concentration (P < 0.05). It was concluded that NEC is a potent inhibitor of microorganism growth.

Availability and cost of wood fuel in 10 years time

International Nuclear Information System (INIS)

Loenner, G.; Danielsson, B.O.; Vikinge, B.; Parikka, M.; Hektor, B.; Nilsson, P.O.

1998-09-01

The potential supply of wood fuel in Sweden is very large. Without reductions from ecological, technical and economic reasons the supply is around 125 TWh per year, depending among other things on the future cut of industrial wood. How much of this gross volume of wood fuel will be available on various time horizons, is however not so clear. The aim of this work has been to estimate technically and economically available quantities of wood fuel in a medium time horizon, around 10 years, and considering ecological considerations. This horizon means that today's best available techniques and methods are assumed to be applied widely, which means that today's lowest cost level will dominate in real terms within around 10 years. The applied methodology means that the potential supply of wood fuel of various types is distributed on different cost influencing factors like terrain class, wood fuel concentration and location in relation to nearest road and final user. All types of wood fuels are included, i.e. logging residues, direct fuel cuttings, industrial by-products and recycled wood. As a whole a large part of the total supply is available with today's best technique and with today's average price level of around 115 SEK per MWh (560 SEK per oven dry tonne). Around 60% or 75 TWh can be considered to be economically available in the medium term. In the long range perspective these figures will probably increase considerably, due primarily to the technical development, and provided that sufficient demand is there 44 refs, 8 figs, 12 tabs, 14 appendixes

Mechanical Properties of Wood Flour Reinforced High Density Polyethylene Composites with Basalt Fibers

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Guojun LU

2014-12-01

Full Text Available Basalt fibers (BFs were surface-treated with a vinyl triethoxy silane coupling agent to improve the mechanical properties of wood fiber-reinforced high density polyethylene (HDPE composites. Basalt fibers were characterized with SEM and FT-IR. The effects of the basalt fiber content and apparent morphology on the mechanical properties of the hybrid composites were investigated in this paper. The results show that the BF coated with the vinyl triethoxy silane coupling agent resulted in an improvement in mechanical properties due to the increased interfacial compatibility between the BF and HDPE. The flexural strength and impact properties significantly increased with 4 wt.% modified basalt fibers. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6441

Branch Wood Decomposition of Tree Species in a Deciduous Temperate Forest in Korea

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Sangsub Cha

2017-05-01

Full Text Available Woody debris, which is supplied by branch litter, is an important component of forest ecosystems as it contains large quantities of organic matter and nutrients. We evaluated changes in branch wood dry weight and nutrient content of six common species (Fraxinus rhynchophylla, Pinus densiflora, Prunus sargentii, Quercus mongolica, Acer pseudosieboldianum, and Symplocos chinensis for. pilosa in a deciduous temperate forest in Korea for 40 months. Branch wood disk samples 1.4–1.6 cm thick were cut, and mass loss was measured over time using the litterbag method. No significant differences in mass loss were recorded among the six tree species. Further, mass loss was negatively correlated with initial lignin concentration and positively correlated with both initial cellulose concentration and wood density for each species. Species with high wood cellulose content had high wood density while the lignin content in wood was relatively low. Accordingly, cellulose contributed to wood density, creating a relatively lower lignin content, and the decreased lignin concentration increased the wood decomposition rate.

Technical assessment of three layered cement-bonded boards produced from wastepaper and sawdust

International Nuclear Information System (INIS)

Fuwape, Joseph Adeola; Fabiyi, James Sunday; Osuntuyi, Edward Olusola

2007-01-01

The technical properties of three layered cement-bonded boards (CBBs) made from wastepaper and sawdust were investigated. The CBBs were produced at three density levels of 1000, 1200 and 1300 kg/m 3 and at four cement/particle ratios of 2.0:1, 2.5:1, 3.0:1 and 3.5:1 on a weight to weight basis. The technical properties evaluated were modulus of rupture (MOR), modulus of elasticity (MOE), water absorption (WA) and thickness swelling (TS). The MOR values ranged from 4.85 to 11.69 MPa and MOE values ranged from 2.80 to 5.57 GPa. The mean values of WA and TS after 24 h of water soaking of the CBBs ranged from 18.18% to 40.49% and 3.55% to 12.13%, respectively. MOR and MOE of the CBBs increased with increase in board density, but MOR decreased with the increase in cement/particle ratio. On the other hand, WA and TS decreased with increase in board density and cement/particle ratio. CBBs produced from wastepaper and sawdust at cement/particle ratios of 3.0:1 and 3.5:1 are suitable for building construction such as paneling, ceiling and partitioning

A Study of Metal-Cement Composites with Additives

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Mironov Victor

2014-12-01

Full Text Available The application of small-sized metal fillers (SMF provides a combination of high bulk density, increased durability and ferromagnetic properties of composite materials on the cement basis. However, the total strength of the composite can be compromised by poor adhesion of metal particles with the cement matrix. The use of versatile additives like microsilica and metakaolin is able to improve the structural integrity and mechanical properties of heavy concretes. The paper considers the results of a study using specimens of heavy concretes with SMF aiming to estimate its strength, structural features and ultrasonic parameters. It was found that the contact of SMF particles with the cement was not perfect, since the voids appeared between them and the cement matrix during the cement hydration process (exothermal reaction. Due to the border porosity, the specimens with the metal fillers have lower compressive strength, lower ultrasound velocity and increased frequency slope of attenuation. Microsilica and metakaolin additives facilitate better contact zone between the cement matrix and metal fillers.

Studies to compare radioactivity of bone cements and their ingredient X-ray contrast media

International Nuclear Information System (INIS)

Hopf, C.; Gloebel, B.; Hopf, T.; Universitaet des Saarlandes, Homburg/Saar; Universitaet des Saarlandes, Homburg/Saar

1990-01-01

Various PMMA bone cements/containing zirconium oxide (ZrO 2 ) as an X-ray contrast medium and zirconium oxides of several manufacturers were tested for their radioactivity by means of a gamma spectrometer. All the bone cements tested (Implast, Palacos R, and Sulfix-6) showed a certain degree of radioactivity. The radiation source in the bone cement is the added zirconium oxide, which is polluted by radioactive elements. The examination of various zirconium oxides showed some high radioactive emissions. (orig./GDG) [de

Enhancement of the Mechanical Properties of Basalt Fiber-Wood-Plastic Composites via Maleic Anhydride Grafted High-Density Polyethylene (MAPE Addition

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Yun Lu

2013-06-01

Full Text Available This study investigated the mechanisms, using microscopy and strength testing approaches, by which the addition of maleic anhydride grafted high-density polyethylene (MAPE enhances the mechanical properties of basalt fiber-wood-plastic composites (BF-WPCs. The maximum values of the specific tensile and flexural strengths are achieved at a MAPE content of 5%–8%. The elongation increases rapidly at first and then continues slowly. The nearly complete integration of the wood fiber with the high-density polyethylene upon MAPE addition to WPC is examined, and two models of interfacial behavior are proposed. We examined the physical significance of both interfacial models and their ability to accurately describe the effects of MAPE addition. The mechanism of formation of the Model I interface and the integrated matrix is outlined based on the chemical reactions that may occur between the various components as a result of hydrogen bond formation or based on the principle of compatibility, resulting from similar polarity. The Model I fracture occurred on the outer surface of the interfacial layer, visually demonstrating the compatibilization effect of MAPE addition.

Enhancement of the Mechanical Properties of Basalt Fiber-Wood-Plastic Composites via Maleic Anhydride Grafted High-Density Polyethylene (MAPE) Addition.

Science.gov (United States)

Chen, Jinxiang; Wang, Yong; Gu, Chenglong; Liu, Jianxun; Liu, Yufu; Li, Min; Lu, Yun

2013-06-18

This study investigated the mechanisms, using microscopy and strength testing approaches, by which the addition of maleic anhydride grafted high-density polyethylene (MAPE) enhances the mechanical properties of basalt fiber-wood-plastic composites (BF-WPCs). The maximum values of the specific tensile and flexural strengths are achieved at a MAPE content of 5%-8%. The elongation increases rapidly at first and then continues slowly. The nearly complete integration of the wood fiber with the high-density polyethylene upon MAPE addition to WPC is examined, and two models of interfacial behavior are proposed. We examined the physical significance of both interfacial models and their ability to accurately describe the effects of MAPE addition. The mechanism of formation of the Model I interface and the integrated matrix is outlined based on the chemical reactions that may occur between the various components as a result of hydrogen bond formation or based on the principle of compatibility, resulting from similar polarity. The Model I fracture occurred on the outer surface of the interfacial layer, visually demonstrating the compatibilization effect of MAPE addition.

DESIGN OF CEMENT COMPOSITES WITH INCREASED IMPERMEABILITY

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Fedyuk Roman Sergeevich

2016-05-01

Full Text Available The paper deals with the development of composite binders for producing concrete with improved characteristics of gas, water and vapor permeability. The authors investigate the processes of composite materials formation in order of decreasing scale levels from macro to nanostructures. The criteria for optimization of the volume of dispersed additives in concrete are offered. The authors theoretically studied the technological features of the formation of hydrated cement stone structure. A positive effect of nanodispersed additives on the structure and physico-mechanical properties of cement composite materials are predicted. Thanks to its improved features, such as good ratio of strength and body density, high density and lifetime, the modified concrete may be used when solving various practical tasks of the construction branch.

Application of Lime Additive on Cementation of Concentrated Low Activities Liquid Radwaste Containing Boric Acid

International Nuclear Information System (INIS)

Bahdir-Johan

2000-01-01

The effect of lime additive on the waste form containing boric acid and the activity 1 μCi/ml have been studied. The studying parameter was the optimum lime additive in concentrate. The sample was made by cement slurry containing boric acid. The cement slurry composition are water/cement ratio (W/C) was 0.35, sand/cement ratio (S/C) was 0.75 and boric (B) was 15000 ppm. On this condition into cement slurry was added the lime additive (K/C) 0.05 -0.8 by weigh. The quality test included density, compressive strength and leaching rate. The density was determination by weighing and measuring sample volume, compressive strength determination using Paul Weber apparatus and leaching rate tested using aquadest. The result of this research are the lime/cement ratio (K/C) 0.30; the density (ρ) 2.449 ± 0.008 g.cm -3 , the compressive strength (Γ) 44.005 ± 0.012 N.mm -2 and the leaching rate (Rn) 7.20x10 -4 -0.90x10 -4 g.cm -2 day -1 . According to this research the quality of the waste form has been complied the IAEA quality standard. (author)

Radiopacity of portland cement associated with different radiopacifying agents.

Science.gov (United States)

Húngaro Duarte, Marco Antonio; de Oliveira El Kadre, Guâniara D'arc; Vivan, Rodrigo Ricci; Guerreiro Tanomaru, Juliane Maria; Tanomaru Filho, Mário; de Moraes, Ivaldo Gomes

2009-05-01

This study evaluated the radiopacity of Portland cement associated with the following radiopacifying agents: bismuth oxide, zinc oxide, lead oxide, bismuth subnitrate, bismuth carbonate, barium sulfate, iodoform, calcium tungstate, and zirconium oxide. A ratio of 20% radiopacifier and 80% white Portland cement by weight was used for analysis. Pure Portland cement and dentin served as controls. Cement/radiopacifier and dentin disc-shaped specimens were fabricated, and radiopacity testing was performed according to the ISO 6876/2001 standard for dental root sealing materials. Using Insight occlusal films, the specimens were radiographed near to a graduated aluminum stepwedge varying from 2 to 16 mm in thickness. The radiographs were digitized and radiopacity compared with the aluminum stepwedge using Digora software (Orion Corporation Soredex, Helsinki, Finland). The radiographic density data were converted into mmAl and analyzed statistically by analysis of variance and Tukey-Kramer test (alpha = 0.05). The radiopacity of pure Portland cement was significantly lower (p cement/radiopacifier mixtures were significantly more radiopaque than dentin and Portland cement alone (p cement/bismuth oxide and Portland cement/lead oxide presented the highest radiopacity values and differed significantly from the other materials (p cement/zinc oxide presented the lowest radiopacity values of all mixtures (p cement as radiopacifying agents. However, the possible interference of the radiopacifiers with the setting chemistry, biocompatibility, and physical properties of the Portland cement should be further investigated before any clinical recommendation can be done.

Increased Coal Replacement in a Cement Kiln Burner by Feeding a Mixture of Solid Hazardous Waste and Shredded Plastic Waste

OpenAIRE

Ariyaratne, W. K. Hiromi; Melaaen, Morten Christian; Tokheim, Lars-André

2013-01-01

The present study aims to find the maximum possible replacement of coal by combined feeding of plastic waste and solid hazardous waste mixed with wood chips (SHW) in rotary kiln burners used in cement kiln systems. The coal replacement should be achieved without negative impacts on product quality, emissions or overall operation of the process. A full-scale experiment was carried out in the rotary kiln burner of a cement kiln by varying SHW and plastic waste feeding rates. Experimental result...

Modeling decay rates of dead wood in a neotropical forest.

Science.gov (United States)

Hérault, Bruno; Beauchêne, Jacques; Muller, Félix; Wagner, Fabien; Baraloto, Christopher; Blanc, Lilian; Martin, Jean-Michel

2010-09-01

Variation of dead wood decay rates among tropical trees remains one source of uncertainty in global models of the carbon cycle. Taking advantage of a broad forest plot network surveyed for tree mortality over a 23-year period, we measured the remaining fraction of boles from 367 dead trees from 26 neotropical species widely varying in wood density (0.23-1.24 g cm(-3)) and tree circumference at death time (31.5-272.0 cm). We modeled decay rates within a Bayesian framework assuming a first order differential equation to model the decomposition process and tested for the effects of forest management (selective logging vs. unexploited), of mode of death (standing vs. downed) and of topographical levels (bottomlands vs. hillsides vs. hilltops) on wood decay rates. The general decay model predicts the observed remaining fraction of dead wood (R2 = 60%) with only two biological predictors: tree circumference at death time and wood specific density. Neither selective logging nor local topography had a differential effect on wood decay rates. Including the mode of death into the model revealed that standing dead trees decomposed faster than downed dead trees, but the gain of model accuracy remains rather marginal. Overall, these results suggest that the release of carbon from tropical dead trees to the atmosphere can be simply estimated using tree circumference at death time and wood density.

Effect of mix proportion of high density concrete on compressive strength, density and radiation absorption

International Nuclear Information System (INIS)

Noor Azreen Masenwat; Mohamad Pauzi Ismail; Suhairy Sani; Ismail Mustapha; Nasharuddin Isa; Mohamad Haniza Mahmud; Mohammad Shahrizan Samsu

2014-01-01

To prevent radiation leaks at nuclear reactors, high-density concrete is used as an absorbent material for radiation from spreading into the environment. High-density concrete is a mixture of cement, sand, aggregate (usually high-density minerals) and water. In this research, hematite stone is used because of its mineral density higher than the granite used in conventional concrete mixing. Mix concrete in this study were divided into part 1 and part 2. In part 1, the concrete mixture is designed with the same ratio of 1: 2: 4 but differentiated in terms of water-cement ratio (0.60, 0.65, 0.70, 0.75, 0.80 ). Whereas, in part 2, the concrete mixture is designed to vary the ratio of 1: 1: 2, 1: 1.5: 3, 1: 2: 3, 1: 3: 6, 1: 2: 6 with water-cement ratio (0.7, 0.8, 0.85, 0.9). In each section, the division has also performed in a mixture of sand and fine sand hematite. Then, the physical characteristics of the density and the compressive strength of the mixture of part 1 and part 2 is measured. Comparisons were also made in terms of absorption of radiation by Cs-137 and Co-60 source for each mix. This paper describes and discusses the relationship between the concrete mixture ratio, the relationship with the water-cement ratio, compressive strength, density, different mixture of sand and fine sand hematite. (author)

Physical and thermal behavior of cement composites reinforced with recycled waste paper fibers

Science.gov (United States)

Hospodarova, Viola; Stevulova, Nadezda; Vaclavik, Vojtech; Dvorsky, Tomas

2017-07-01

In this study, three types of recycled waste paper fibers were used to manufacture cement composites reinforced with recycled cellulosic fibers. Waste cellulosic fibers in quantity of 0.2, 0.3, and 0.5 wt.% were added to cement mixtures. Physical properties such as density, water capillarity, water absorbability and thermal conductivity of fiber cement composites were studied after 28 days of hardening. However, durability of composites was tested after their water storage up to 90 days. Final results of tested properties of fiber cement composites were compared with cement reference sample without cellulosic fibers.

Effect of explant density and volume of cultivation medium on in-vitro multiplication of blueberry (Vaccinium corymbosum L. varieties "Brigitta" and "Legacy"

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Mario Rodríguez Beraud

2015-03-01

Full Text Available The objective of the investigation was to evaluate the in-vitro multiplication of two varieties of blueberry (Vaccinium corymbosum L., “Brigitta” and “Legacy” in response to five explants densities (5, 10, 15, 20 and 25 and four flask volumes (10, 20, 30 and 40 mL for cultivation. For both varieties the cultivation medium WPM (Woody Plant Medium was used. The experiment was completely randomized with 20 treatments and 12 repetitions per treatment. After 45 days of cultivation we evaluated the height of shoots, number of shoots/explant, number of nodes/shoot and number of shoots/flask. Variety “Brigitta” had highest shoots at higher densities and flask volumes, while variety “Legacy” had the highest average shoot height with intermediate densities and high volumes. Regarding the number of shoots/explant, the volume of the medium had no influence on “Brigitta”, however, higher plant densities affected this parameter. With variety “Legacy” the maximum number of shoots was achieved with lower plant densities and intermediate culture volumes per flask. In relation to the number of nodes per explant "Brigitta had lower numbers as compared to “Legacy”, but with both varieties the number of nodes decresed with smaller volumes of medium in the flasks. For the number of shoots per flask, “Brigitta” responsed best at higher densities exceeding 40 shoots per flask. In contrast, “Legacy” produced maximum results at density of 25 explants in 30 mL of medium. It is concluded that for the optimum multiplication of both varieties the correct selection of both, the planting density and the volume of multiplication medium are important.

Evaluation of cement composites for tritiated water fixation, 1

International Nuclear Information System (INIS)

Amano, Hiroshi; Sakuma, Youichi; Okamoto, Tadashi; Utsunomiya, Toru; Moriya, Toshio; Shimbo, Takashi; Higuchi, Masanori.

1985-01-01

The integrity of a waste package of tritiated waste is one of the most important parameters in proceeding safety assessments of tritiated waste disposal systems. Of the many terms governing the integrity of a waste package, the one that is directly connected with safety assessment is the leach rate of tritium from the solidified object. Experiments focusing on measurements of leach rates were therefore conducted. These experiments consisted of three stages, in the first stage experiment, types of cement and mix proportions were selected on the bases of (1) weight reduction, (2) micro-structure, (3) compressive strength, (4) ignition loss, and (5) chemical analysis. And two mix proportions each, for normal portland cement and special cement, were chosen for further testing. In the second stage, as a preliminary experiment for measuring the leach rate of tritium, the leach rate of deuterium was studied by measuring densities of immersed liquid. The examination of the relations between the leach rates and the beforementioned properties ((1) to (4) in the first stage experiment) clearly showed that the lower leach rate were achieved with the lower water-cement ratio which represented the higher density of the cement form. In the third stage experiment, it is planned hereafter to confirm the above results by carrying out leach tests for tritium. (author)

Bacterial community succession in pine-wood decomposition

Directory of Open Access Journals (Sweden)

Anna eKielak

2016-03-01

Full Text Available Though bacteria and fungi are common inhabitants of decaying wood, little is known about the relationship between bacterial and fungal community dynamics during natural wood decay. Based on previous studies involving inoculated wood blocks, strong fungal selection on bacteria abundance and community composition was expected to occur during natural wood decay. Here we focused on bacterial and fungal community compositions in pine wood samples collected from dead trees in different stages of decomposition. We showed that bacterial communities undergo less drastic changes than fungal communities during wood decay. Furthermore, we found that bacterial community assembly was a stochastic process at initial stage of wood decay and became more deterministic in later stages, likely due to environmental factors. Moreover, composition of bacterial communities did not respond to the changes in the major fungal species present in the wood but rather to the stage of decay reflected by the wood density. We concluded that the shifts in the bacterial communities were a result of the changes in wood properties during decomposition and largely independent of the composition of the wood-decaying fungal communities.

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.

Optimization of properties of cement-bonded particleboard manufactured from cotton stalk and sawdust containing calcium chloride CaCl2 as an additive

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morteza nazerian

2016-06-01

Full Text Available The aim of this study was investigation of hydration behavior and mechanical properties of cement-bonded particleboard manufactured from different ratio of cotton stalk to poplar wood particle, sawdust content and CaCl2 as additive at different weight ratios. At the first, curing time of cement paste containing different amount of additive (CaCl2 and wood and cotton fines was determined. Besides, the effect of additive (CaCl2 content, weight ratio of cotton to poplar wood particles and percentage of sawdust on modulus of rupture (MOR, modulus of elasticity (MOE and internal bonding (IB of cement-bonded particleboard was evaluated by response surface methodology (RSM. In order to optimize the properties of panels, a mathematical model equation (second order plan was done by a computer simulation program. According to results, there is a good coincidence between predicted values and actual values (R2 for MOR, MOE and IB was 0.93, 0.90 and 0.95, respectively. This study showed that the response surface methodology (RSM can be effectively used for modeling of panel properties. Results showed that using weight ratio of cotton to poplar particle 43:57 the MOR, MOE and IB of panels can be reached to maximum values (12.5, 2545 and 0.35 MPa, respectively. Simultaneously, application of 4.5% additive and 9% sawdust at had a positive effect on the properties of the panels.

Density and Specific Gravity Metrics in Biomass Research

Science.gov (United States)

Micheal C. Wiemann; G. Bruce Williamson

2012-01-01

Following the 2010 publication of Measuring Wood Specific Gravity… Correctly in the American Journal of Botany, readers contacted us to inquire about application of wood density and specific gravity to biomass research. Here we recommend methods for sample collection, volume measurement, and determination of wood density and specific gravity for...

Utilization of the national Portland cement for immobilizing radioactive wastes - Physical characteristics

International Nuclear Information System (INIS)

Rzyski, B.M.; Suarez, A.A.

1988-01-01

This paper shows the results obtained in the study of the national Portland cement, P320, as matrix for radioactive nitric waste incorporation. Cement use practice in other countries is common for this purposes and demonstrates to be cheap and accessible when low and medium level wastes are immobilized. Some of physical characteristics as: homogeneity,mechanical strenght, setting and porosity are analysed due to water-cement ratio and salt contents. Those characteristics which are proper of the final product, must be controlled in such way to assure a long time integrity of the wasteform. The establishment of process and quality control criteria are based in such kind of data. (author) [pt

Comparative hydraulic architecture of tropical tree species representing a range of successional stages and wood density.

Science.gov (United States)

McCulloh, Katherine A; Meinzer, Frederick C; Sperry, John S; Lachenbruch, Barbara; Voelker, Steven L; Woodruff, David R; Domec, Jean-Christophe

2011-09-01

Plant hydraulic architecture (PHA) has been linked to water transport sufficiency, photosynthetic rates, growth form and attendant carbon allocation. Despite its influence on traits central to conferring an overall competitive advantage in a given environment, few studies have examined whether key aspects of PHA are indicative of successional stage, especially within mature individuals. While it is well established that wood density (WD) tends to be lower in early versus late successional tree species, and that WD can influence other aspects of PHA, the interaction of WD, successional stage and the consequent implications for PHA have not been sufficiently explored. Here, we studied differences in PHA at the scales of wood anatomy to whole-tree hydraulic conductance in species in early versus late successional Panamanian tropical forests. Although the trunk WD was indistinguishable between the successional groups, the branch WD was lower in the early successional species. Across all species, WD correlated negatively with vessel diameter and positively with vessel packing density. The ratio of branch:trunk vessel diameter, branch sap flux and whole-tree leaf-specific conductance scaled negatively with branch WD across species. Pioneer species showed greater sap flux in branches than in trunks and a greater leaf-specific hydraulic conductance, suggesting that pioneer species can move greater quantities of water at a given tension gradient. In combination with the greater water storage capacitance associated with lower WD, these results suggest these pioneer species can save on the carbon expenditure needed to build safer xylem and instead allow more carbon to be allocated to rapid growth.

HYDRATION PROCESS AND MECHANICAL PROPERTIES OF CEMENT PASTE WITH RECYCLED CONCRETE POWDER AND SILICA SAND POWDER

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Jaroslav Topič

2017-11-01

Full Text Available Recycled concrete powder (RCP mostly consisting of cement paste could be reused as partial cement replacement. The aim of this paper is to compare hydration and mechanical properties of RCP and two types of silica sand powder (SSP. Comparison of those materials combined with cement can highlight the binder properties of recycled concrete powder. Using of two types of SSP also show an influence of their fines on hydration process and mechanical properties. Particle size analysis and calorimetric measurement were carried out and mechanical properties such as bulk density, dynamic Young’s modulus and compression strength were examine. Calorimetric measurement proves the presence of exposed non-hydrated particles in RCP that can react again. However lower density of old cement paste in RCP overweight the mentioned potential of RCP and mechanical properties are decreasing compared with reference cement paste and cement paste SSP.

Comparative study of methods to measure the density of Cementious powders

OpenAIRE

Helsel, Michelle A.; Ferraris, Chiara F.; Bentz, Dale

2015-01-01

The accurate measurement of the density of hydraulic cement has an essential role in the determination of concrete mixture proportions. As more supplementary cementitious materials (SCM), such as fly ash, and slag, or cement replacements materials such as limestone and calcium carbonate are used in blended cements, knowledge of the density of each powder or of the blended cement would allow a more accurate calculation of the proportions of a concrete mixture by volume instead of by mass. The ...

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

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.

Acoustic probing of elastic behavior and damage in weakly cemented granular media

Science.gov (United States)

Langlois, V.; Jia, X.

2014-02-01

We investigate the elastic behavior and damage of weakly cemented granular media under external load with ultrasound. The cementation controlled experiments are performed by freezing the capillary liquid at the bead contact in a dense glass or polymeric [poly(methyl methacrylate)] bead pack wet by tetradecane of volume fraction ϕ = 0.1%-4%. When the pendular rings are solidified, an abrupt increase by a factor of 2 in the compressional wave velocity is observed. We interpret the data in terms of effective medium models in which the contact stiffnesses are derived by either a bonded contact model [P. J. Digby, J. Appl. Mech. 48, 803 (1981), 10.1115/1.3157738] or a cemented contact model [J. Dvorkin, A. Nur, and H. Yin, Mech. Mater. 18, 351 (1994), 10.1016/0167-6636(94)90044-2]. The former fails to quantitatively account for the results with a soft cement relative to the grain, whereas the latter considering the mechanical properties of the cement does apply. Moreover, we monitor the irreversible behavior of the cemented granular packs under moderate uniaxial loading (cemented materials is accompanied by a compressional wave velocity decrease up to 60%, likely due to the fractures induced at the grain-cement interfaces.

Benefits and drawbacks of zinc in glass ionomer bone cements

Energy Technology Data Exchange (ETDEWEB)

Brauer, Delia S; Hill, Robert G [Unit of Dental Physical Sciences, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Gentleman, Eileen; Stevens, Molly M [Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Farrar, David F, E-mail: d.brauer@qmul.ac.uk [Smith and Nephew Research Centre, York Science Park, Heslington YO10 5DF (United Kingdom)

2011-08-15

Glass polyalkenoate (ionomer) cements (GPCs) based on poly(acrylic acid) and fluoro-alumino-silicate glasses are successfully used in a variety of orthopaedic and dental applications; however, they release small amounts of aluminium, which is a neurotoxin and inhibits bone mineralization in vivo. Therefore there has been significant interest in developing aluminium-free glasses containing zinc for forming GPCs because zinc can play a similar structural role in the glass, allowing for glass degradation and subsequent cement setting, and is reported to have beneficial effects on bone formation. We created zinc-containing GPCs and characterized their mechanical properties and biocompatibility. Zinc-containing cements showed adhesion to bone close to 1 MPa, which was significantly greater than that of zinc-free cements (<0.05 MPa) and other currently approved biological adhesives. However, zinc-containing cements produced significantly lower metabolic activity in mouse osteoblasts exposed to cell culture medium conditioned with the cements than controls. Results show that although low levels of zinc may be beneficial to cells, zinc concentrations of 400 {mu}M Zn{sup 2+} or more resulted in cell death. In summary, we demonstrate that while zinc-containing GPCs possess excellent mechanical properties, they fail basic biocompatibility tests, produce an acute cytotoxic response in vitro, which may preclude their use in vivo.

ANATOMICAL AND PHYSICAL PROPERTIESOF BISBUL WOOD (Diospyros blancoi A.DC.

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Krisdianto Krisdianto

2005-03-01

Full Text Available Ebony (Diospyros sp.  is a heavy hardwood that is  popularly known as blackwood. Diospyros consists of over 300 species spread throughout tropics area and about 100 species occur in Indonesia. Bisbul wood (Diospyros btancoi A.DC. is one species of  streaked ebony that is locally known as 'buah mentega'.  The anatomical and physical properties of  bisbul  were studied to collect information  for wood identification  and to support appropriate use of the timber. Anatomical properties were studied from microtome sectioned samples, which have been coloured by safranin and mounted by entellan, while fiber dimensions  were studied from macerated samples.  Physical properties  of  bisbul wood studied include moisture content, density and percentage of volumetric shrinkage. Moisture content and density were studied from 20 x 20 x 20 mm samples based on wet and oven dry condition. Volumetric shrinkage was measured from dimension changes in radial, tangential and longitudinal shrinkage of 20 x 20 x 40 mm samples. The samples were measured in wet and oven dry conditions. The main anatomical characteristics to identify bisbul wood were black wood with pinkish streaked, heavy and very hard,  very fine texture, even, lustrous surface and glossy, distinct growth ring, small size of vessels, apotracheal parenchyma forming reticulate pattern. The average moisture content was 59.86 ± 2.84%,  the density average was 0.74 ± 0.04 gr/cm3  and volumetric shrinkage was 10.41±0.70%.   The higher the stem, the more moisture  content and the lower the density will be. Sapwood density was lower and had more moisture  content than heartwood. The black pinkish heavy wood, bisbul was recommended to be used for carvings, sculpture, souvenir and luxuryinterior products.

Effect of surface texturing on friction properties of WC/Co cemented carbide

International Nuclear Information System (INIS)

Wu, Ze; Deng, Jianxin; Xing, Youqiang; Cheng, Hongwei; Zhao, Jun

2012-01-01

Highlights: ► Tribological properties of surface textured WC/Co cemented carbide were studied. ► Textured surfaces have better performance of antifriction and antiwear. ► Area density of textures has significant effect on tribological performance. -- Abstract: An experimental study was carried out to investigate the tribological properties of different surface textured WC/Co cemented carbide. The influence of applied load, sliding speed and area density of textures on frictional performance of surface textured patterns was investigated by Taguchi method. Results show that the textured surfaces filled with molybdenum disulfide solid lubricants can reduce the average friction coefficient, wear rates of Ti–6Al–4V alloy balls and adhesion of Ti–6Al–4V alloy materials on the worn track of cemented carbide compared with un-textured ones. Variance analysis of the experimental data indicates that the area density of textures plays major contribution of both average friction coefficient and wear rate of Ti–6Al–4V alloy balls. Higher area density of textures is beneficial to improve tribological performance of the cemented carbide samples. Sliding speed seems to have no effect on the tribological performance of textured surfaces within the reliability interval of 90%. Applied load has effect on both average friction coefficient and wear rate of Ti–6Al–4V alloy balls at the reliability interval of 95%.

Light-weight wood-magnesium oxychloride cement composite building products made by extrusion

OpenAIRE

Zhou, X; Li, Z

2012-01-01

This is the post-print version of the final paper published in Construction and Building Materials. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2011 Elsevier B.V. Magnesium oxychloride (MOC) cement is ...

How to quantify conduits in wood?

Science.gov (United States)

Scholz, Alexander; Klepsch, Matthias; Karimi, Zohreh; Jansen, Steven

2013-01-01

Vessels and tracheids represent the most important xylem cells with respect to long distance water transport in plants. Wood anatomical studies frequently provide several quantitative details of these cells, such as vessel diameter, vessel density, vessel element length, and tracheid length, while important information on the three dimensional structure of the hydraulic network is not considered. This paper aims to provide an overview of various techniques, although there is no standard protocol to quantify conduits due to high anatomical variation and a wide range of techniques available. Despite recent progress in image analysis programs and automated methods for measuring cell dimensions, density, and spatial distribution, various characters remain time-consuming and tedious. Quantification of vessels and tracheids is not only important to better understand functional adaptations of tracheary elements to environment parameters, but will also be essential for linking wood anatomy with other fields such as wood development, xylem physiology, palaeobotany, and dendrochronology.

FIELD-SCALE LEACHING OF ARSENIC, CHROMIUM AND COPPER FROM WEATHERED TREATED WOOD

Science.gov (United States)

Hasan, A. Rasem; Hu, Ligang; Solo-Gabriele, Helena M.; Fieber, Lynne; Cai, Yong; Townsend, Timothy G.

2010-01-01

Earlier studies documented the loss of wood preservatives from new wood. The objective of this study was to evaluate losses from weathered treated wood under field conditions by collecting rainfall leachate from 5 different wood types, all with a surface area of 0.21 m2. Wood samples included weathered chromate copper arsenate (CCA) treated wood at low (2.7 kg/m3), medium (4.8 kg/m3) and high (35.4 kg/m3) retention levels, new alkaline copper quat (ACQ) treated wood (1.1 kg/m3 as CuO) and new untreated wood. Arsenic was found to leach at a higher rate (100 mg in 1 year for low retention) than chromium and copper (leached at the highest rate from the ACQ sample (670 mg). Overall results suggest that metals’ leaching is a continuous process driven by rainfall, and that the mechanism of release from the wood matrix changes as wood weathers. PMID:20053493

Variability in energy and carbon dioxide balances of wood and concrete building materials

Energy Technology Data Exchange (ETDEWEB)

Gustavsson, Leif; Sathre, Roger [Ecotechnology, Mid Sweden University, SE-831 25 OEstersund (Sweden)

2006-07-15

A variety of factors affect the energy and CO{sub 2} balances of building materials over their lifecycle. Previous studies have shown that the use of wood for construction generally results in lower energy use and CO{sub 2} emission than does the use of concrete. To determine the uncertainties of this generality, we studied the changes in energy and CO{sub 2} balances caused by variation of key parameters in the manufacture and use of the materials comprising a wood- and a concrete-framed building. Parameters considered were clinker production efficiency, blending of cement, crushing of aggregate, recycling of steel, lumber drying efficiency, material transportation distance, carbon intensity of fossil fuel, recovery of logging, sawmill, construction and demolition residues for biofuel, and growth and exploitation of surplus forest not needed for wood material production. We found the materials of the wood-framed building had lower energy and CO{sub 2} balances than those of the concrete-framed building in all cases but one. Recovery of demolition and wood processing residues for use in place of fossil fuels contributed most significantly to the lower energy and CO{sub 2} balances of wood-framed building materials. We conclude that the use of wood building material instead of concrete, coupled with greater integration of wood by-products into energy systems, would be an effective means of reducing fossil fuel use and net CO{sub 2} emission to the atmosphere. (author)

Variability in energy and carbon dioxide balances of wood and concrete building materials

International Nuclear Information System (INIS)

Gustavsson, Leif; Sathre, Roger

2006-01-01

A variety of factors affect the energy and CO 2 balances of building materials over their lifecycle. Previous studies have shown that the use of wood for construction generally results in lower energy use and CO 2 emission than does the use of concrete. To determine the uncertainties of this generality, we studied the changes in energy and CO 2 balances caused by variation of key parameters in the manufacture and use of the materials comprising a wood- and a concrete-framed building. Parameters considered were clinker production efficiency, blending of cement, crushing of aggregate, recycling of steel, lumber drying efficiency, material transportation distance, carbon intensity of fossil fuel, recovery of logging, sawmill, construction and demolition residues for biofuel, and growth and exploitation of surplus forest not needed for wood material production. We found the materials of the wood-framed building had lower energy and CO 2 balances than those of the concrete-framed building in all cases but one. Recovery of demolition and wood processing residues for use in place of fossil fuels contributed most significantly to the lower energy and CO 2 balances of wood-framed building materials. We conclude that the use of wood building material instead of concrete, coupled with greater integration of wood by-products into energy systems, would be an effective means of reducing fossil fuel use and net CO 2 emission to the atmosphere. (author)

Radiologic diagnosis of gastro-oesophageal reflux. Comparison of barium and low-density contrast medium

Energy Technology Data Exchange (ETDEWEB)

Fransson, S.G.; Soekjer, H.; Johansson, K.E.; Tibbling, L.

It has been proposed that the high density of ordinary barium suspension may complicate the radiologic diagnosis of gastro-oesophageal reflux. For this reason P-contrast was developed (Ferring AB); a contrast medium with the same density as water (1 g/cm/sup 3/). A comparison of P-contrast and barium (Mixobar Ventrikel 400 mg/ml) was performed in 82 patients. All patients were examined with both contrast media and the findings were compared with those at reflux test at manometry, endoscopy and 24-hour pH monitoring. Another 40 patients and 15 symptom-free controls were examined with two different amounts of barium, 100 ml and 200 ml, to study if the radiologic diagnosis of reflux varied with the volume of contrast medium administered. P-contrast was found to have no advantages over barium for the diagnosis of gastro-oesophageal reflux. The outcome of the radiologic examination was not influenced by the different volumes of barium used.

THE USE OF SISAL FIBRE AS REINFORCEMENT IN CEMENT BASED COMPOSITES

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Romildo Dias Tolêdo Filho

1999-08-01

Full Text Available ABSTRACT The inclusion of fibre reinforcement in concrete, mortar and cement paste can enhance many of the engineering properties of the basic materials, such as fracture toughness, flexural strength and resistance to fatigue, impact, thermal shock and spalling. In recent years, a great deal of interest has been created worldwide on the potential applications of natural fibre reinforced, cement based composites. Investigations have been carried out in many countries on various mechanical properties, physical performance and durability of cement based matrices reinforced with naturally occurring fibres including sisal, coconut, jute, bamboo and wood fibres. These fibres have always been considered promising as reinforcement of cement based matrices because of their availability, low cost and low consumption of energy. In this review, the general properties of the composites are described in relation to fibre content, length, strength and stiffness. A chronological development of sisal fibre reinforced, cement based matrices is reported and experimental data are provided to illustrate the performance of sisal fibre reinforced cement composites. A brief description on the use of these composite materials as building products has been included. The influence of sisal fibres on the development of plastic shrinkage in the pre-hardened state, on tensile, compressive and bending strength in the hardened state of mortar mixes is discussed. Creep and drying shrinkage of the composites and the durability of natural fibres in cement based matrices are of particular interest and are also highlighted. The results show that the composites reinforced with sisal fibres are reliable materials to be used in practice for the production of structural elements to be used in rural and civil construction. This material could be a substitute asbestos-cement composite, which is a serious hazard to human and animal health and is prohibited in industrialized countries. The

Controls on Cementation in a Chalk Reservoir

DEFF Research Database (Denmark)

Meireles, Leonardo Teixeira Pinto; Hussein, A.; Welch, M.J.

In this study, we identify different controls on cementation in a chalk reservoir. Biot’s coefficient, a measure of cementation, stiffness and strength in porous rocks, is calculated from logging data (bulk density and sonic Pwave velocity). We show that Biot’s coefficient is correlated...... to the water saturation of the Kraka reservoir and is partly controlled by its stratigraphic sub-units. While the direct causal relationship between Biot’s coefficient and water saturation cannot be extended for Biot’s coefficient and porosity, a correlation is also identified between the two, implying...

Adhesion quality of glued joints from different commercial wood species

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Alexandre Miguel do Nascimento

2013-12-01

Full Text Available The objective of this study was to determine the effect of wood density, adhesive type and gluing pressure on the shear strength of glued joints of fourteen commercial wood species. Wood pieces were classified in three density classes (Class 1: less than 0.55 g cm-3; Class 2: from 0.55 to 0.75 g cm-3; and Class 3: greater than 0.75 g cm-3 and joints bonded with two adhesives: polyvinyl acetate (PVA and urea-formaldehyde (UF, under two different pressures: 6 and 12 kgf cm-2. Glued joints bonded with PVA adhesive presented higher shear strength than those bonded with UF adhesive. For percentage of wood failure, the PVA adhesive had the best performance, however, only Classes 1 and 2 reached the values required by ASTM 3110 standard. Glued joints from Class 3, bonded with UF adhesive, did not reach the values of solid wood. The gluing pressure of 12 kgf cm-2 was more efficient for Class 3, for both shear strength and percentage of wood failure.

Tracing nitrogen accumulation in decaying wood and examining its impact on wood decomposition rate

Science.gov (United States)

Rinne, Katja T.; Rajala, Tiina; Peltoniemi, Krista; Chen, Janet; Smolander, Aino; Mäkipää, Raisa

2016-04-01

Decomposition of dead wood, which is controlled primarily by fungi is important for ecosystem carbon cycle and has potentially a significant role in nitrogen fixation via diazotrophs. Nitrogen content has been found to increase with advancing wood decay in several studies; however, the importance of this increase to decay rate and the sources of external nitrogen remain unclear. Improved knowledge of the temporal dynamics of wood decomposition rate and nitrogen accumulation in wood as well as the drivers of the two processes would be important for carbon and nitrogen models dealing with ecosystem responses to climate change. To tackle these questions we applied several analytical methods on Norway spruce logs from Lapinjärvi, Finland. We incubated wood samples (density classes from I to V, n=49) in different temperatures (from 8.5oC to 41oC, n=7). After a common seven day pre-incubation period at 14.5oC, the bottles were incubated six days in their designated temperature prior to CO2 flux measurements with GC to determine the decomposition rate. N2 fixation was measured with acetylene reduction assay after further 48 hour incubation. In addition, fungal DNA, (MiSeq Illumina) δ15N and N% composition of wood for samples incubated at 14.5oC were determined. Radiocarbon method was applied to obtain age distribution for the density classes. The asymbiotic N2 fixation rate was clearly dependent on the stage of wood decay and increased from stage I to stage IV but was substantially reduced in stage V. CO2 production was highest in the intermediate decay stage (classes II-IV). Both N2 fixation and CO2 production were highly temperature sensitive having optima in temperature 25oC and 31oC, respectively. We calculated the variation of annual levels of respiration and N2 fixation per hectare for the study site, and used the latter data together with the 14C results to determine the amount of N2 accumulated in wood in time. The proportion of total nitrogen in wood

Wood wastes and residues generated along the Colorado Front Range as a potential fuel source

Science.gov (United States)

Julie E. Ward; Kurt H. Mackes; Dennis L. Lynch

2004-01-01

Throughout the United States there is interest in utilizing renewable fuel sources as an alternative to coal and nat-ural gas. This project was initiated to determine the availability of wood wastes and residues for use as fuel in ce-ment kilns and power plants located along the Colorado Front Range. Research was conducted through literature searches, phone surveys,...

Changes in CT density-measurement of intraorbital wooden foreign bodies

International Nuclear Information System (INIS)

Otani, Etsuko; Hiyama, Fusako; Machi, Setsuko; Hagihara, Masahiro.

1991-01-01

We examined in vitro changes in CT density-measurement of intraorbital wooden foreign bodies. Dry wooden sticks were immersed in distilled water, saline, and serum. Computerized tomography scans were taken several times during 22 weeks. Scans were taken in room air and in fatty tissue. The CT density-measurement of the central part of the wooden bodies was calculated. That of the dry wood was about 500 HU; all of the wooden foreign bodies became denser during the 22 weeks, with those immersed in distilled water and saline at about 130 HU, and those immersed in serum at about 150 HU. It was confirmed that wood becomes denser after soaking in aqueous environments. The CT density of wood soaked in water depends on the density of wood fiber, and the CT density of the wood fiber itself. (author)

The use of additive ceramic hollow spheres on cement slurry to prevent lost circulation in formation `X' having low pressure fracture

Science.gov (United States)

Rita, Novia; Mursyidah, Syahindra, Michael

2018-03-01

When drilling, if the hydrostatic pressure is higher than formation pressure (fracture pressure) it will cause lost circulation during cementing process. To solve this problem, hydrostatic pressure of slurry can be decreased by lowering the slurry density by using some additives. Ceramic Hollow Spheres (CHS) is lightweight additive. This additive comes with low specific gravity so it can lowered the slurry density. When the low-density slurry used in cementing process, it can prevent low circulation and fractured formation caused by cement itself. Class G cement is used in this experiment with the standard density of this slurry is 15.8 ppg. With the addition of CHS, slurry density lowered to 12.5 ppg. CHS not only used to lower the slurry density, it also used to make the same properties with the standard slurry even the density has been lowered. Both thickening time and compressive strength have not change if the CHS added to the slurry. With addition of CHS, thickening time at 70 Bc reached in 03 hours 12 minutes. For the compressive strength, 2000 psi reached in 07 hours 07 minutes. Addition of CHS can save more time in cementing process of X formation.

Corrosion of metal containers containing cemented radioactive wastes

International Nuclear Information System (INIS)

Duffo, G.S.; Farina, S.B.; Schulz, F.M.; Marotta, F

2010-01-01

Nuclear activities generate different kinds of radioactive wastes. In the case of Argentina, wastes classified as low and medium level are conditioned in metal drums for final disposal in a repository whose design is based on the use of multiple and independent barriers. Nuclear energy plants generate a large volume of mid-level radioactive wastes, consisting mainly of ion-exchange resins contaminated by fission products. Other contaminated products such as gloves, papers, clothing, rubber and plastic tubing, can be incinerated and the ashes from the combustion also constitute wastes that must be disposed of. These wastes (resins and ashes) must be immobilized in order to avoid the release of radionuclides into the environment. The wastes usually undergo a process of cementing to immobilize them. This work aims to systematically study the process of degradation by corrosion of the steel drums in contact with the cemented resins and with the ashes cemented with the addition of different types and concentrations of aggressive compounds (chloride and sulfate). The specimens are configured so that the parameters of interest for the steel in contact with the cemented materials can be measured. The variables of corrosion potential, electric resistivity of the matrix and polarization resistance (PR) were monitored and show that the presence of chloride increases the susceptibility to corrosion of the drum steel that is in contact with the cement resin matrix

In Vitro Evaluation of Planktonic Growth on Experimental Cement-Retained Titanium Surfaces

Science.gov (United States)

Balci, Nur; Cakan, Umut; Aksu, Burak; Akgul, Oncu; Ulger, Nurver

2016-01-01

Background The purpose of this study was to compare the effects of selected cements, or their combination with titanium, on the growth of two periodontopathic bacteria: Prevotella intermedia (Pi) and Fusobacterium nucleatum (Fn). Material/Methods This study was comprised of several experimental groups: 1) Dental luting cements (glass ionomer cement, methacrylate-based resin cement, zinc-oxide eugenol cement, eugenol-free zinc oxide cement; 2) titanium discs; and 3) titanium combination cement discs. The disks were submerged in bacterial suspensions of either Fn or Pi. Planktonic bacterial growth within the test media was measured by determining the optical density of the cultures (OD600). Mean and standard deviations were calculated for planktonic growth from three separate experiments. Results Intergroup comparison of all experimental groups revealed increased growth of Pi associated with cement-titanium specimens in comparison with cement specimens. Regarding the comparison of all groups for Fn, there was an increased amount of bacterial growth in cement-titanium specimens although the increase was not statistically significant. Conclusions The combination of cement with titanium may exacerbate the bacterial growth capacity of Pi and Fn in contrast to their sole effect. PMID:27058704

In Vitro Evaluation of Planktonic Growth on Experimental Cement-Retained Titanium Surfaces.

Science.gov (United States)

Balci, Nur; Cakan, Umut; Aksu, Burak; Akgul, Oncu; Ulger, Nurver

2016-04-08

BACKGROUND The purpose of this study was to compare the effects of selected cements, or their combination with titanium, on the growth of two periodontopathic bacteria: Prevotella intermedia (Pi) and Fusobacterium nucleatum (Fn). MATERIAL AND METHODS This study was comprised of several experimental groups: 1) Dental luting cements (glass ionomer cement, methacrylate-based resin cement, zinc-oxide eugenol cement, eugenol-free zinc oxide cement; 2) titanium discs; and 3) titanium combination cement discs. The disks were submerged in bacterial suspensions of either Fn or Pi. Planktonic bacterial growth within the test media was measured by determining the optical density of the cultures (OD600). Mean and standard deviations were calculated for planktonic growth from three separate experiments. RESULTS Intergroup comparison of all experimental groups revealed increased growth of Pi associated with cement-titanium specimens in comparison with cement specimens. Regarding the comparison of all groups for Fn, there was an increased amount of bacterial growth in cement-titanium specimens although the increase was not statistically significant. CONCLUSIONS The combination of cement with titanium may exacerbate the bacterial growth capacity of Pi and Fn in contrast to their sole effect.

Pretreatment Characteristics of Waste Oak Wood by Ammonia Percolation

Science.gov (United States)

Kim, Jun-Seok; Kim, Hyunjoon; Lee, Jin-Suk; Lee, Joon-Pyo; Park, Soon-Chul

A log of waste oak wood collected from a Korean mushroom farm has been tested for ammonia percolation pretreatment. The waste log has different physical characteristics from that of virgin oak wood. The density of the waste wood was 30% lower than that of virgin oak wood. However, there is little difference in the chemical compositions between the woods. Due to the difference in physical characteristics, the optimal pretreatment conditions were also quite different. While for waste oak the optimum temperature was determined to be 130°C, for virgin oak wood the optimum pretreatment was only achieved at 170°C. Presoaking for 12 h with ammonia solution before pretreatment was helpful to increase the delignification efficiency.

Dielectric study on hierarchical water structures restricted in cement and wood materials

International Nuclear Information System (INIS)

Abe, Fumiya; Nishi, Akihiro; Saito, Hironobu; Asano, Megumi; Watanabe, Seiei; Kita, Rio; Shinyashiki, Naoki; Yagihara, Shin; Fukuzaki, Minoru; Sudo, Seiichi; Suzuki, Youki

2017-01-01

Dielectric relaxation processes for mortar observed by broadband dielectric spectroscopy were analyzed in the drying and hydration processes for an aging sample in the frequency region from 1 MHz up to 2 MHz. At least two processes for structured water in the kHz frequency region and another mHz relaxation process affected by ionic behaviors were observed. Comparison of the relaxation parameters obtained for the drying and hydration processes suggests an existence of hierarchical water structures in the exchange of water molecules, which are originally exchanged from free water observed at around 20 GHz. The water molecules reflected in the lower frequency process of the two kHz relaxation processes are more restricted and take more homogeneous structures than the higher kHz relaxation process. These structured water usually hidden in large ionic behaviors for wood samples was observed by electrodes covered by a thin Teflon film, and hierarchical water structures were also suggested for wood samples. Dielectric spectroscopy technique is an effective tool to analyze the new concept of hierarchical water structures in complex materials. (paper)

Bridging the gaps: An overview of wood across time and space in diverse rivers

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Wohl, Ellen

2017-02-01

Nearly 50 years of research focused on large wood (LW) in rivers provide a basis for understanding how wood enters rivers; how wood decays, breaks, and is transported downstream; and how at least temporarily stable wood influences channel geometry, fluxes of water, sediment, and organic matter, and the abundance and diversity of aquatic and riparian organisms. Field-based studies have led to qualitative conceptual models and to numerical stimulations of river processes involving wood. Numerous important gaps remain, however, in our understanding of wood dynamics. The majority of research on wood in rivers focuses on small- to medium-sized rivers, defined using the ratio of wood piece size to channel width as channels narrower than the locally typical wood-piece length (small) and slightly narrower than the longer wood pieces present (medium). Although diverse geographic regions and biomes are represented by one or a few studies in each region, the majority of research comes from perennial rivers draining temperate conifer forests. Regional syntheses most commonly focus on the Pacific Northwest region of North America where most of these studies originate. Consequently, significant gaps in our understanding include lack of knowledge of wood-related processes in large rivers, dryland rivers, and rivers of the high and low latitudes. Using a wood budget as an organizing framework, this paper identifies other gaps related to wood recruitment, transport, storage, and how beavers influence LW dynamics. With respect to wood recruitment, we lack information on the relative importance of mass tree mortality and transport of buried or surficial downed wood from the floodplain into the channel in diverse settings. Knowledge gaps related to wood transport include transport distances of LW and thresholds for LW mobility in small to medium rivers. With respect to wood storage, we have limited data on longitudinal trends in LW loads within unaltered large and great rivers and on

Medium Density Fibreboard Made of Acetylated Sludge from Paper Mill

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Luthfi Hakim

2013-03-01

Full Text Available Research of using sludge as raw material for making medium density fibreboard (MDF was useful to create additional value of sludge. The objective of the research was to evaluate physical properties, mechanical properties, and durability of MDF from acetylated sludge in 4 levels of acetate anhydride (0%, 3%, 5%, and 7% with 3 replicates. The MDF was made using dry process. After materials were mixed with adhesives, they were pressed using hotpress under 170 oC temperature and 45 Pa pressure for 25 minutes. The size of the MDF sample was 25 cm x 20 cm x 1 cm with 0.8 g/cm3 density. The physical properties (density, moisture content, water absorption, thickness swelling and mechanical properties (modulus of elasticity, modulus of rupture, internal bond, screw holding power was tested based on JIS A 5905-2003 standard. The durability was evaluated using SNI 01-7207-2006. All physical properties of MDF fulfill JIS A 5905-2003. Acetate anhydride decreased the moisture content value of MDF. On the other hand, all mechanical properties did not fulfill the standard. That was caused by calcium carbonate in sludge that blocked the adhesion between sludge fibres. The durability of MDF tested here was classified Class I which is very resistant to termites.

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.

Radioactive waste-Portland cement systems: I, radionuclide distribution

International Nuclear Information System (INIS)

Jantzen, C.M.; Glasser, F.P.; Lachowski, E.E.

1984-01-01

Crystal chemical stabilization of radioactive wastes can be achieved during clinkering of, or with, ordinary portland cement. Waste loadings of 20 to 30 wt% are achieved by dilute solid solution of waste ions into cementitious host lattices. Higher waste loadings result in compatible noncementitious radiophases. The cementitious phases hydrate without loss of compressive strength. Crystallochemical relationships predict that the radionuclide partitioning in the anhydrous clinkered phases will be maintained in the hydration products. These cementitious hydroxylated radiophases would be in internal equilibrium under anticipated repository conditions. The radionuclide distributions observed are described in the context of established phase equilibria for commercial waste cement systems, but are applicable to transuranic, medium- and low-level wastes

Cemented total knee replacement in 24 dogs: surgical technique, clinical results, and complications.

Science.gov (United States)

Allen, Matthew J; Leone, Kendall A; Lamonte, Kimberly; Townsend, Katy L; Mann, Kenneth A

2009-07-01

To characterize the performance of cemented total knee replacement (TKR) in dogs. Preclinical research study. Skeletally mature, male Hounds (25-30 kg; n=24) with no preexisting joint pathology. Dogs had unilateral cemented TKR and were evaluated at 6, 12, 26, or 52 weeks (6 dogs/time point) by radiography, bone density analysis, visual gait assessment, and direct measurement of thigh circumference and stifle joint range of motion as indicators of functional recovery. At study end, the stability of the cemented tibial component was determined by destructive mechanical testing. Joint stability was excellent in 16 dogs (67%) and good in 8 dogs. None of the tibial components had evidence of migration or periprosthetic osteolysis whereas 1 femoral component was loose at 52 weeks. There was an early and significant decrease in tibial bone density, likely because of disuse of the operated limb. Dogs returned to full activity by 12 weeks. The tibial cement-bone interface maintained its strength over 52 weeks. Cement provides stable fixation of the tibial component in canine TKR. Cemented TKR yields adequate clinical function and stifle joint excursion in the dog. Clinical studies are needed to determine the long-term fate of cemented TKR implants, to assess the influence of implant design on implant fixation and wear, and to obtain objective functional data.

What is the cementation exponent? A new differential interpretation

Science.gov (United States)

Glover, P. W. J.

2009-04-01

Between 1950 and 2002 the total volume of reserves discovered has run to over 1500 Bbbl. for oil and 7.5 Tcf. for gas. Over half of these resources has already been produced, and has driven the global economy for the last fifty years. All of the assessments of the volume of hydrocarbon reserves were made using Archie's relationships (1942). It would be difficult, therefore, to overestimate the impact of either the petrophysical techniques or Archie's relationships on the worldwide economy. Archie's laws link the electrical resistivity of a rock to its porosity, to the resistivity of the water that saturates its pores, and to the fractional saturation of the pore space with the water, and are used to calculate the hydrocarbon saturation of the reservoir rock from which the reserves are then calculated. Archie's laws contain two exponents, m and n, which Archie called the cementation exponent and the saturation exponent, respectively. The conductivity of the hydrocarbon saturated rock is highly sensitive to changes in either exponent. However, despite the importance of the cementation exponent, few petrophysicists, commercial or academic, are able to describe its real physical meaning. The purpose of this contribution is to investigate the elusive physical meaning of the cementation exponent. We review the traditional interpretation of the cementation exponent and consider the extension of Archie's first law to two conducting phases. Consequently, we develop a new differential interpretation of the cementation exponent that is based on a new definition for the connectedness of the conducting phases in a porous medium. In this interpretation the connectedness of a porous medium is defined as the availability of pathways for transport, where the connectedness is the inverse of the formation resistivity factor, G = σo σw = 1 F (and may also be called the conductivity formation factor). Porosity is defined as the fractional amount of pore space in the usual manner

Cementation of Nuclear Graphite Using Geopolymers

International Nuclear Information System (INIS)

Girke, N.A.; Steinmetz, H-J.; Bukaemsky, A.; Bosbach, D.; Hermann, E.; Griebel, I.

2016-01-01

Geopolymers are solid aluminosilicate materials usually formed by alkali hydroxide or alkali silicate activation of solid precursors such as coal fly ash, calcined clay and/or metallurgical slag. Today the primary application of geopolymer technology is in the development of alternatives to Portland-based cements. Variations in the ratio of aluminium to silicon, and alkali to silicon or addition of structure support, produce geopolymers with different physical and mechanical properties. These materials have an amorphous three-dimensional structure that gives geopolymers certain properties, such as fire and acid resistance, low leach rate, which make them an ideal substitute for ordinary Portland cement (OPC) in a wide range of applications especially in conditioning and storage of radioactive waste. Therefore investigations have been initiated on how and to which amount graphite as a hydrophobic material can be mixed with cement or concrete to form stable waste products and which concretes fulfil the necessary specifications best. As a result, geopolymers have been identified as a promising matrix for graphite containing nuclear wastes. With geopolymers, both favourable properties in the cementation process and a high long time structural stability of the products can be achieved. Investigations include: • direct mixing of graphite with geopolymers with or without sand as a mechanically stabilizing medium; • production of cement-graphite granulates as intermediate products and embedding of these granulates in geopolymer; • coating of formed graphite pieces with geopolymer.The report shows that carbon in the form of graphite can both be integrated with different grain size spectra as well as shaped in the hydraulic binder geopolymer and meets the requirements for a stable long-term immobilisation. (author)

Accelerated weathering of composite cements used for immobilisation

International Nuclear Information System (INIS)

Borges, P. H. R.; Milestone, N. B.; Streatfield, R. E.

2008-01-01

Trying to estimate the long-term durability of cemented waste-forms is a difficult task as the cement matrix is a reactive medium and interactions can occur with the encapsulated waste as well as with the environment. There are few studies of samples that have been stored under controlled conditions for more than 10-15 years. waste-forms are now being expected to last hundreds of years, much of that likely to be in some form of storage where sample integrity is important. There is also the concern that results from any long-term samples may only be indicative as both formulations and materials change with time. This paper discusses changes in physical properties that occur in composite cements when some of the short-term accelerated procedures employed in construction testing are applied to encapsulating matrices. Changes after increased temperature of curing, wetting/drying and accelerated carbonation are discussed. Many of the encapsulating formulations currently used are composite cements where large replacement levels of OPC with supplementary cementing materials (SCMs) such as PFA or BFS are made, primarily to reduce heat output. Accelerating the exposure conditions, either by increasing temperature or through wetting/drying has the effect of changing the hydration pattern of the composite cement by generating more hydration in the SCMs than would normally occur. The large amount of porosity that occurs because of limited hydration allows intrusion of gases and ready movement of water, so the samples subjected to accelerated testing do not appear as durable as expected if stored at ambient. (authors)

EARLY AFTERGLOWS OF GAMMA-RAY BURSTS IN A STRATIFIED MEDIUM WITH A POWER-LAW DENSITY DISTRIBUTION

International Nuclear Information System (INIS)

Yi, Shuang-Xi; Dai, Zi-Gao; Wu, Xue-Feng

2013-01-01

A long-duration gamma-ray burst (GRB) has been widely thought to arise from the collapse of a massive star, and it has been suggested that its ambient medium is a homogenous interstellar medium (ISM) or a stellar wind. There are two shocks when an ultra-relativistic fireball that has been ejected during the prompt gamma-ray emission phase sweeps up the circumburst medium: a reverse shock that propagates into the fireball, and a forward shock that propagates into the ambient medium. In this paper, we investigate the temporal evolution of the dynamics and emission of these two shocks in an environment with a general density distribution of n∝R –k (where R is the radius) by considering thick-shell and thin-shell cases. A GRB afterglow with one smooth onset peak at early times is understood to result from such external shocks. Thus, we can determine the medium density distribution by fitting the onset peak appearing in the light curve of an early optical afterglow. We apply our model to 19 GRBs and find that their k values are in the range of 0.4-1.4, with a typical value of k ∼ 1, implying that this environment is neither a homogenous ISM with k = 0 nor a typical stellar wind with k = 2. This shows that the progenitors of these GRBs might have undergone a new mass-loss evolution

Spheroidization of glass powders for glass ionomer cements.

Science.gov (United States)

Gu, Y W; Yap, A U J; Cheang, P; Kumar, R

2004-08-01

Commercial angular glass powders were spheroidized using both the flame spraying and inductively coupled radio frequency plasma spraying techniques. Spherical powders with different particle size distributions were obtained after spheroidization. The effects of spherical glass powders on the mechanical properties of glass ionomer cements (GICs) were investigated. Results showed that the particle size distribution of the glass powders had a significant influence on the mechanical properties of GICs. Powders with a bimodal particle size distribution ensured a high packing density of glass ionomer cements, giving relatively high mechanical properties of GICs. GICs prepared by flame-spheroidized powders showed low strength values due to the loss of fine particles during flame spraying, leading to a low packing density and few metal ions reacting with polyacrylic acid to form cross-linking. GICs prepared by the nano-sized powders showed low strength because of the low bulk density of the nano-sized powders and hence low powder/liquid ratio of GICs.

Refined pipe theory for mechanistic modeling of wood development.

Science.gov (United States)

Deckmyn, Gaby; Evans, Sam P; Randle, Tim J

2006-06-01

We present a mechanistic model of wood tissue development in response to changes in competition, management and climate. The model is based on a refinement of the pipe theory, where the constant ratio between sapwood and leaf area (pipe theory) is replaced by a ratio between pipe conductivity and leaf area. Simulated pipe conductivity changes with age, stand density and climate in response to changes in allocation or pipe radius, or both. The central equation of the model, which calculates the ratio of carbon (C) allocated to leaves and pipes, can be parameterized to describe the contrasting stem conductivity behavior of different tree species: from constant stem conductivity (functional homeostasis hypothesis) to height-related reduction in stem conductivity with age (hydraulic limitation hypothesis). The model simulates the daily growth of pipes (vessels or tracheids), fibers and parenchyma as well as vessel size and simulates the wood density profile and the earlywood to latewood ratio from these data. Initial runs indicate the model yields realistic seasonal changes in pipe radius (decreasing pipe radius from spring to autumn) and wood density, as well as realistic differences associated with the competitive status of trees (denser wood in suppressed trees).

Conventional dual-cure versus self-adhesive resin cements in dentin bond integrity

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Renata Andreza Talaveira da Silva

2011-08-01

Full Text Available During post preparation, the root canal is exposed to the oral cavity, and endodontic treatment may fail because of coronal leakage, bacterial infection and sealing inability of the luting cement. OBJECTIVE: this study quantified the interfacial continuity produced with conventional dual-cure and self-adhesive resin cements in the cervical (C, medium (M and apical (A thirds of the root. MATERIAL AND METHODS: Forty single-rooted human teeth were restored using Reforpost # 01 conical glass-fiber posts and different materials (N=10 per group: group AC=Adper™ ScotchBond™ Multi-purpose Plus + AllCem; group ARC=Adper™ ScotchBond™ Multi-purpose Plus + RelyX ARC; group U100=RelyX U100; and group MXC=Maxcem Elite. After being kept in 100% humidity at 37°C for 72 hours, the samples were sectioned parallel to their longitudinal axis and positive epoxy resin replicas were made. The scanning electron micrographs of each third section of the teeth were combined using Image Analyst software and measured with AutoCAD-2002. We obtained percentage values of the interfacial continuity. RESULTS: Interfacial continuity was similar in the apical, medium and cervical thirds of the roots within the groups (Friedman test, p>0.05. Comparison of the different cements in a same root third showed that interfacial continuity was lower in MXC (C=45.5%; M=48.5%; A=47.3% than in AC (C=85.9%, M=81.8% and A=76.0%, ARC (C=83.8%, M=82.4% and A=75.0% and U100 (C=84.1%, M=82.4% and A=77.3% (Kruskal-Wallis test, p<0.05. CONCLUSIONS: Allcem, Rely X ARC and U100 provide the best cementation; cementation was similar among root portions; in practical terms, U100 is the best resin because it combines good cementation and easy application and none of the cements provides complete interfacial continuity.

Conventional dual-cure versus self-adhesive resin cements in dentin bond integrity

Science.gov (United States)

da SILVA, Renata Andreza Talaveira; COUTINHO, Margareth; CARDOZO, Pedro Igor; da SILVA, Larissa Alves; ZORZATTO, José Roberto

2011-01-01

During post preparation, the root canal is exposed to the oral cavity, and endodontic treatment may fail because of coronal leakage, bacterial infection and sealing inability of the luting cement. Objective this study quantified the interfacial continuity produced with conventional dual-cure and self-adhesive resin cements in the cervical (C), medium (M) and apical (A) thirds of the root. Material and methods Forty single-rooted human teeth were restored using Reforpost # 01 conical glass-fiber posts and different materials (N=10 per group): group AC=Adper™ ScotchBond™ Multi-purpose Plus + AllCem; group ARC=Adper™ ScotchBond™ Multi-purpose Plus + RelyX ARC; group U100=RelyX U100; and group MXC=Maxcem Elite. After being kept in 100% humidity at 37ºC for 72 hours, the samples were sectioned parallel to their longitudinal axis and positive epoxy resin replicas were made. The scanning electron micrographs of each third section of the teeth were combined using Image Analyst software and measured with AutoCAD-2002. We obtained percentage values of the interfacial continuity. Results Interfacial continuity was similar in the apical, medium and cervical thirds of the roots within the groups (Friedman test, p>0.05). Comparison of the different cements in a same root third showed that interfacial continuity was lower in MXC (C=45.5%; M=48.5%; A=47.3%) than in AC (C=85.9%, M=81.8% and A=76.0%), ARC (C=83.8%, M=82.4% and A=75.0%) and U100 (C=84.1%, M=82.4% and A=77.3%) (Kruskal-Wallis test, p<0.05). Conclusions Allcem, Rely X ARC and U100 provide the best cementation; cementation was similar among root portions; in practical terms, U100 is the best resin because it combines good cementation and easy application and none of the cements provides complete interfacial continuity. PMID:21710099

Non-destructive analysis of chlorine in fly ash cement concrete

International Nuclear Information System (INIS)

Naqvi, A.A.; Garwan, M.A.; Nagadi, M.M.; Maslehuddin, M.; Al-Amoudi, O.S.B.; Khateeb-ur-Rehman

2009-01-01

Preventive measures against reinforcement corrosion in concrete require increasing concrete density to prevent the diffusion of chloride ions to the steel surface. Pozzolanic materials, such as fly ash (FA), silica fume (SF), and blast furnace slag (BFS) are added to concrete to increase its density. Monitoring the chloride concentration in concrete is required to assess the chances of reinforcement corrosion. In this study, FA was added to Portland cement concrete to increase its density. Prompt gamma neutron activation analysis (PGNAA) technique was utilized to analyze the concentration of chlorine in concrete. The chlorine concentration in the FA cement concrete was evaluated by determining the yield of 1.16, 1.95, 6.11, 6.62, 7.41, 7.79, and 8.58 MeV gamma-rays of chlorine from the FA concrete specimen containing 0.4-3.5 wt% chlorine. An excellent agreement was noted between the experimental yield of the prompt gamma-rays and the calculated yield obtained through the Monte Carlo simulations. The Minimum Detectable Concentration (MDC) of chlorine in FA cement concrete was also calculated. The best value of MDC limit of chlorine in the FA cement concrete was found to be 0.022±0.007 and 0.038±0.017 wt% for 1.16 and 6.11 MeV prompt gamma-rays, respectively. Within the statistical uncertainty, the lower bound of MDC meets the maximum permissible limit of 0.03 wt% of chlorine in concrete set by American Concrete Institute Committee 318.

Non-destructive analysis of chlorine in fly ash cement concrete

Energy Technology Data Exchange (ETDEWEB)

Naqvi, A.A. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)], E-mail: aanaqvi@kfupm.edu.sa; Garwan, M.A.; Nagadi, M.M. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Maslehuddin, M. [Center for Engineering Research, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Al-Amoudi, O.S.B. [Department of Civil Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Khateeb-ur-Rehman [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

2009-08-11

Preventive measures against reinforcement corrosion in concrete require increasing concrete density to prevent the diffusion of chloride ions to the steel surface. Pozzolanic materials, such as fly ash (FA), silica fume (SF), and blast furnace slag (BFS) are added to concrete to increase its density. Monitoring the chloride concentration in concrete is required to assess the chances of reinforcement corrosion. In this study, FA was added to Portland cement concrete to increase its density. Prompt gamma neutron activation analysis (PGNAA) technique was utilized to analyze the concentration of chlorine in concrete. The chlorine concentration in the FA cement concrete was evaluated by determining the yield of 1.16, 1.95, 6.11, 6.62, 7.41, 7.79, and 8.58 MeV gamma-rays of chlorine from the FA concrete specimen containing 0.4-3.5 wt% chlorine. An excellent agreement was noted between the experimental yield of the prompt gamma-rays and the calculated yield obtained through the Monte Carlo simulations. The Minimum Detectable Concentration (MDC) of chlorine in FA cement concrete was also calculated. The best value of MDC limit of chlorine in the FA cement concrete was found to be 0.022{+-}0.007 and 0.038{+-}0.017 wt% for 1.16 and 6.11 MeV prompt gamma-rays, respectively. Within the statistical uncertainty, the lower bound of MDC meets the maximum permissible limit of 0.03 wt% of chlorine in concrete set by American Concrete Institute Committee 318.

Properties of Eucalyptus benthamii wood for energy production

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Dimas Agostinho Silva

2015-12-01

Full Text Available The objective of this study was to evaluate the energy potential of Eucalyptus benthamii Maiden et Cambage wood. The samples were collected in the municipality of Cerro Negro, Santa Catarina State, Brazil. Samples were collected from 5 trees at 0%, 25%, 50%, 75% and 100% of commercial height. It was determined basic density, high calorific value, elemental composition, immediate chemical analysis, lower calorific value, energy density, carbon storage and energy production. The physical and chemical variables studied and energy potential of wood did not present differences along the stem.

Utilization of barite/cement composites for gamma rays attenuation

Science.gov (United States)

Sakr, Khaled; Ramadan, Wageeh; Sayed, Magda; El-Zakla, Tarek; El-Desouqy, Mohamed; El-Faramawy, Nabil

2018-04-01

The present work is directed to investigate the contribution of adding barite aggregates to cement as a shielding material for radioactive wastes disposal facilities. The percentages of barite from 5% up to 20% mixed with cement with different grain sizes were examined. Mechanical and physical properties such as compressive strength, wet and dry densities, water absorption, and porosity have been investigated. The thermogravimetric analysis and X-ray diffraction were used to examine the thermal stability and the characterizations of studied samples, respectively. The linear attenuation coefficient, mean free path, half value layer, and transmission fraction were evaluated. All the nuclear shielding parameters revealed the uppermost values for cement mixed with 5% barite of size range 250-600 µm. The attenuation coefficient of the investigated samples displayed an increase by more than 125% than that of neat cement.

Effects of Energy Density and Shielding Medium on Performance of Laser Beam Welding (LBW) Joints on SAF2205 Duplex Stainless Steel

Science.gov (United States)

Zhang, W. W.; Cong, S.; Luo, S. B.; Fang, J. H.

2018-05-01

The corrosion resistance performance of SAF2205 duplex stainless steel depends on the amount of ferrite to austenite transformation, but the ferrite content after power beam welding is always excessively high. To obtain laser beam welding joints with better mechanical and corrosion resistance performance, the effects of the energy density and shielding medium on the austenite content, hardness distribution, and shear strength were investigated. The results showed that ferrite to austenite transformation was realized with increase in the energy density. When the energy density was increased from 120 J/mm to 200 J/mm, the austenite content of the welding joint changed from 2.6% to 38.5%. Addition of nitrogen gas to the shielding medium could promote formation of austenite. When the shielding medium contained 50% and 100% nitrogen gas, the austenite content of the welding joint was 42.7% and 47.2%, respectively. The hardness and shear strength were significantly improved by increase in the energy density. However, the shielding medium had less effect on the mechanical performance. Use of the optimal welding process parameters resulted in peak hardness of 375 HV and average shear strength of 670 MPa.

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

Improving wood hydrolyzate fermentation by using schizosaccharomycetes

Energy Technology Data Exchange (ETDEWEB)

Kalyuzhnyi, M Ya; Ustinova, V I; Petrushko, G I

1967-01-01

The development of Schizosaccharomycetes (I) in wood hydrolyzates is not observed when fermentation is carried out by the convetional batch process, evidently because of the highly inhibitory action of the medium. More recently, with the introduction of continuous fermentation of wood and other hydrolyzates, the occurrence of I has been frequently reported, and in some hydrolysis plants, I became predominant, eliminating the budding yeast strains. The phenomenon can be attributed to higher temperatures employed in continuous fermentation, and to a more favorable medium, as the hydrolyzate is diluted with spent fermentation liquor (the flow of fresh medium constitutes about 20% of the fermentation-vat volume). The I cells, when grown under favorable conditions, have a high fermenting power, adapt easily to the fermentation of galactose, and give higher yields of ethanol than the budding yeast. As observed at plants using I, however, the cells are sensitive to variations in the fermentation process, and are inactivated upon storage. This is usually attributed to their inability to store polysaccharides, and especially glycogen. An experimental study undertaken to determine conditions under which reserve polysaccharides accumulate in I cells showed that the important factor is the quality of the medium in which the cells are grown and the conditions of storage. In media enriched with spent fermentaion liquor or with cell autolyzate and purified from toxic components, considerable amounts of glycogen accumulate in the cells.

Correlated random-phase approximation from densities and in-medium matrix elements

Energy Technology Data Exchange (ETDEWEB)

Trippel, Richard; Roth, Robert [Institut fuer Kernphysik, Technische Universitaet Darmstadt (Germany)

2016-07-01

The random-phase approximation (RPA) as well as the second RPA (SRPA) are established tools for the study of collective excitations in nuclei. Addressing the well known lack of correlations, we derived a universal framework for a fully correlated RPA based on the use of one- and two-body densities. We apply densities from coupled cluster theory and investigate the impact of correlations. As an alternative approach to correlations we use matrix elements transformed via in-medium similarity renormalization group (IM-SRG) in combination with RPA and SRPA. We find that within SRPA the use of IM-SRG matrix elements leads to the disappearance of instabilities of low-lying states. For the calculations we use normal-ordered two- plus three-body interactions derived from chiral effective field theory. We apply different Hamiltonians to a number of doubly-magic nuclei and calculate electric transition strengths.

Radon exhalation study from cement, cement slabs and concrete slabs with variation in fly ash

International Nuclear Information System (INIS)

Sharma, Nisha; Singh, Jaspal

2012-01-01

Fly ash is a waste product from coal-fired power plants. Fly ash has become a subject of world-wide interest in recent years because of its diverse uses, e.g. in the manufacture of concrete for building purposes, for the filling of underground cavities, or as a component of building material. The fly ash may contain enhanced levels of the natural radionuclides in the uranium and thorium series and by using the fly ash in building materials, the radiation levels in houses may thus be technologically enhanced. Because of its relatively high radionuclide contents (including 226 Ra), fly ash may, however, present a potential hazard to the population through its radon emanation, which would be highly undesirable. Since fly ash is frequently used as a building material, the idea of the experiment was to mix fly ash in different proportions in the cement in the powder form, cemented slabs and concrete slabs to study the combined behaviors. Alpha sensitive LR-115 type II plastic track detector, commonly known as Solid State Nuclear Track Detectors (SSNTDs), were used to measure the radon concentration. The alpha particles emitted from the radon causes the radiation damaged tracks. The chemical etching in NaOH at 60°C for about 90 minutes was done to reveal these latent tracks, which were then scanned and counted by an optical microscope of suitable magnification. By calculating the track density of registered tracks, the radon concentrations were determined. In case of cement in the powder form and in cemented slab, starting from the pure cement, fly ash was added up to 70% by weight. In this case the radon exhalation rate has increased by addition of fly ash in the cement and in case of concrete slabs by the addition of fly ash in the cement the radon exhalation increases up to 60% and then decreases. Therefore, on the basis of our investigations we concluded that in general radon exhalation rate increases with the addition of fly ash. (author)

A novel wood flour-filled composite based on microfibrillar high-density polyethylene (HDPE)/Nylon-6 blends.

Science.gov (United States)

Liu, Hongzhi; Yao, Fei; Xu, Yanjun; Wu, Qinglin

2010-05-01

A novel wood flour (WF)-filled composite based on the microfibrillar high-density polyethylene (HDPE) and Nylon-6 co-blend, in which both in situ formed Nylon-6 microfibrils and WF acted as reinforcing elements, was successfully developed using a two-step extrusion method. At the 30wt.% WF loading level, WF-filled composite based on the microfibrillized HDPE/Nylon-6 blend exhibited higher strengths and moduli than the corresponding HDPE-based composite. The incorporation of WF reduced short-term creep response of HDPE matrix and the presence of Nylon-6 microfibrils further contributed to the creep reduction. Copyright 2009 Elsevier Ltd. All rights reserved.

Physical, mechanical, and biodegradable properties of meranti wood polymer composites

International Nuclear Information System (INIS)

Enamul Hoque, M.; Aminudin, M.A.M.; Jawaid, M.; Islam, M.S.; Saba, N.; Paridah, M.T.

2014-01-01

Highlights: • In-situ polymerization and solution casting method used to manufacture WPC. • In-situ WPC exhibited better properties compared to pure wood, 5% WPC and 20% WPC. • Lowest water absorption and least biodegradability shown by In-situ wood. - Abstract: In-situ polymerization and solution casting techniques are two effective methods to manufacture wood polymer composites (WPCs). In this study, wood polymer composites (WPCs) were manufactured from meranti sapwood by solution casting and in-situ polymerization process using methyl methacrylate (MMA) and epoxy matrix respectively. Physical, mechanical, and morphological characterizations of fabricated WPCs were then carried out to analyse their properties. Morphological properties of composites samples were analyzed through scanning electron microscopy (SEM). The result reveals that in-situ wood composite exhibited better properties compared to pure wood, 5% WPC and 20% WPC. Moreover, in-situ WPC had lowest water absorption and least biodegraded. Conversely, pure wood shown moderate mechanical strength, high biodegradation and water absorption rate. In term of biodegradation, earth-medium brought more severe effect than water in deteriorating the properties of the specimens

Comparison of Different Wood Species as Raw Materials for Bioenergy

Directory of Open Access Journals (Sweden)

Bojana Klašnja

2013-12-01

Full Text Available Background and Purpose: Most projections of the global energy use predict that biomass will be an important component of primary energy sources in the coming decades. Short rotation plantations have the potential to become an important source of renewable energy in Europe because of the high biomass yields, a good combustion quality as solid fuel, ecological advantages and comparatively low biomass production costs. Materials and Methods: In this study, the wood of black locust Robinia pseudoacacia, white willow Salix alba L., poplars Populus deltoides and Populus x euramericana cl.I-214, aged eight years were examined. Immediately after the felling, sample discs were taken to assess moisture content, ash content, the width of growth rings, wood densities and calorific values, according to the standard methodology. Results:The mean values of willow, poplar and black locust wood density were 341 kg/m3, 336 kg/m3 and 602 kg/m3,respectively. The average heating values of willow poplar and black locust wood were 18.599 MJ/kg, 18.564 MJ/kg and 21.196 MJ/kg, respectively. The FVI index (average values was higher for black locust (17.186 than for poplar and willow clones, which were similar: 11.312 and 11.422 respectively. Conclusions: Black locust wood with a higher density, calorific value and ash content compared to poplar and willow wood proved to be a more suitable raw material as RES. However, it is very important, from the aspect of the application of wood of these tree species as RES, to also consider the influence of the biomass yield per unit area of the plantations established as “energy plantations”.

Effect of Basal Medium, Explants Size and Density on the In Vitro Proliferation and Growth of Date Palm (Phoenix dactylifera L. Cultivar ‘16-bis’

Directory of Open Access Journals (Sweden)

Mouaad Amine MAZRI

2013-08-01

Full Text Available The effect of basal medium, explant size and density on shoot multiplication, growth, rooting and acclimatization of date palm cv. ‘16-bis’ was evaluated. Bud clusters of different sizes (2, 3, 4 and 5 buds per cluster were cultured at density of 1, 2, 3 and 4 clusters on Murashige and Skoog medium (MS, woody plant medium (WPM and Nitsch medium (NM supplemented with 0.5 mg/L 2-naphthoxyacetic acid and 0.5 mg/L kinetin for three months (multiplication phase. Separated shoots of different sizes (<3 cm; 3 to 4.5 cm and 4.5 to 6 cm were cultured at density of 1, 2, 3 and 4 shoots on hormone free MS medium, WPM or NM for three months (Elongation-rooting phase. The proliferation and development of shoots were affected by the basal medium, explant size and density. The optimal shoot proliferation (18.1 was observed when 4 buds clusters were cultured at the density of 2 clusters per jar in MS medium. Separated shoots of 4.5 to 6 cm length exhibited the optimal in vitro development in terms of leaf length and greening, and root number and length when cultured on MS medium. In addition, these shoots reached the highest acclimation frequency with 80%. Our results would be utilized for an efficient propagation of plantlets of cv. ‘16-bis’, a selected date palm cultivar resistant to the bayoud disease.

Thermal Properties of Cement-Based Composites for Geothermal Energy Applications

Science.gov (United States)

Bao, Xiaohua; Memon, Shazim Ali; Yang, Haibin; Dong, Zhijun; Cui, Hongzhi

2017-01-01

Geothermal energy piles are a quite recent renewable energy technique where geothermal energy in the foundation of a building is used to transport and store geothermal energy. In this paper, a structural–functional integrated cement-based composite, which can be used for energy piles, was developed using expanded graphite and graphite nanoplatelet-based composite phase change materials (CPCMs). Its mechanical properties, thermal-regulatory performance, and heat of hydration were evaluated. Test results showed that the compressive strength of GNP-Paraffin cement-based composites at 28 days was more than 25 MPa. The flexural strength and density of thermal energy storage cement paste composite decreased with increases in the percentage of CPCM in the cement paste. The infrared thermal image analysis results showed superior thermal control capability of cement based materials with CPCMs. Hence, the carbon-based CPCMs are promising thermal energy storage materials and can be used to improve the durability of energy piles. PMID:28772823

Thermal Properties of Cement-Based Composites for Geothermal Energy Applications

Directory of Open Access Journals (Sweden)

Xiaohua Bao

2017-04-01

Full Text Available Geothermal energy piles are a quite recent renewable energy technique where geothermal energy in the foundation of a building is used to transport and store geothermal energy. In this paper, a structural–functional integrated cement-based composite, which can be used for energy piles, was developed using expanded graphite and graphite nanoplatelet-based composite phase change materials (CPCMs. Its mechanical properties, thermal-regulatory performance, and heat of hydration were evaluated. Test results showed that the compressive strength of GNP-Paraffin cement-based composites at 28 days was more than 25 MPa. The flexural strength and density of thermal energy storage cement paste composite decreased with increases in the percentage of CPCM in the cement paste. The infrared thermal image analysis results showed superior thermal control capability of cement based materials with CPCMs. Hence, the carbon-based CPCMs are promising thermal energy storage materials and can be used to improve the durability of energy piles.

Thermal Properties of Cement-Based Composites for Geothermal Energy Applications.

Science.gov (United States)

Bao, Xiaohua; Memon, Shazim Ali; Yang, Haibin; Dong, Zhijun; Cui, Hongzhi

2017-04-27

Geothermal energy piles are a quite recent renewable energy technique where geothermal energy in the foundation of a building is used to transport and store geothermal energy. In this paper, a structural-functional integrated cement-based composite, which can be used for energy piles, was developed using expanded graphite and graphite nanoplatelet-based composite phase change materials (CPCMs). Its mechanical properties, thermal-regulatory performance, and heat of hydration were evaluated. Test results showed that the compressive strength of GNP-Paraffin cement-based composites at 28 days was more than 25 MPa. The flexural strength and density of thermal energy storage cement paste composite decreased with increases in the percentage of CPCM in the cement paste. The infrared thermal image analysis results showed superior thermal control capability of cement based materials with CPCMs. Hence, the carbon-based CPCMs are promising thermal energy storage materials and can be used to improve the durability of energy piles.

A Planning Guide for Small and Medium Size Wood Products Companies

Science.gov (United States)

Jeff Howe; Stephen Bratkovich

2005-01-01

At the beginning of the 21st century, North American wood products companies are facing competitive pressure from numerous sources. Traditional products are being manufactured in new regions (e.g., China and the developing nations), and substitute products are being developed by competing industries (e.g., plastics and composites). The bottom line is strained by...

Effect of Water-Cement Ratio on Pore Structure and Strength of Foam Concrete

Directory of Open Access Journals (Sweden)

Zhongwei Liu

2016-01-01

Full Text Available Foam concrete with different dry densities (400, 500, 600, 700, and 800 kg/m3 was prepared from ordinary Portland cement (P.O.42.5R and vegetable protein foaming agent by adjusting the water-cement ratio through the physical foaming method. The performance of the cement paste adopted, as well as the structure and distribution of air pores, was characterized by a rheometer, scanning electron microscope, vacuum water saturation instrument, and image analysis software. Effects of the water-cement ratio on the relative viscosity of the cement paste, as well as pore structure and strength of the hardened foam concrete, were discussed. Results showed that water-cement ratio can influence the size, distribution, and connectivity of pores in foam concrete. The compressive strength of the foam concrete showed an inverted V-shaped variation law with the increase in water-cement ratio.

Low-NO{sub x}, wood chip combustion

Energy Technology Data Exchange (ETDEWEB)

Saastamoinen, J.; Oravainen, H.; Haemaelaeinen, J.; Paakkinen, K. [VTT Energy, Jyvaeskylae (Finland)

1997-10-01

The regulations for nitrogen oxide emissions vary in different countries, but the general trend in the future will probably be that the emissions limits will be lowered also for wood combustion plants, which are small or medium size units. Thus, the development of wood chip burning furnaces (grate furnaces, fluidized bed combustors, stoker furnaces) with lower nitrogen oxide emissions, is important. The wood used in the combustor, its particle size, moisture and fuel properties (nitrogen content) affect the nitrogen emissions. The nitrogen oxide release is also much affected by the design and operation of the combustor (air staging, fuel air preheat, flue gas circulation, air to fuel mass ratio). The fate of nitrogen compounds originally in the virgin wood depends much on the design of the combustor system and by proper planning it is possible to reduce the emission of nitrogen oxides. Basic knowledge of the release of nitrogen compounds from single wood particles is attained. The release of gaseous nitrogen compounds from wood particles during pyrolysis and combustion is studied experimentally and by modelling. Nitrogen release is studied experimentally by two ways, by analysing the gas and by quenching the particle and analysing the char residue. Formation of nitrogen oxide emissions in a fuel bed is studied by modelling and by combustion experiments with a pot furnace. This research gives general information of nitrogen oxide formation in wood bunting especially in fixed beds. The development of a horizontal stoker burner for wood chips with low emissions is the practical aim of the research. (orig.)

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.

Alpha radioactivity in Indian cement samples

International Nuclear Information System (INIS)

Nain, M.; Chauhan, R. P.; Chakarvarti, S. K.

2006-01-01

The essential constituents of radioactive and each of cements like lime, silica and alumina are derived from earth's crust in which radioactive elements like uranium, thorium etc are also present in varying amounts almost everywhere. These two elements are considered as the parent elements of uranium and thorium radioactive decay series in which radon and thoron are produced respectively as decay products. In the present study the samples of ordinary Portland cement , Portland pozzolana cement and some other cementious finishing materials like white cement, Plaster of Paris , cement putty etc were collected and analysed for radium and radon concentrations along with radon exhalation rates. Materials and Methods: Alpha sensitive LR-115 Type II plastic track detectors commonly known as S olid State Nuclear Track Detectors w ere used to measure the radium and radon concentration. The alpha particles emitted from the radon causes the radiation damaged tracks. The Chemical etching in NaOH at 60 C for about 90 minutes was done to reveal these latent tracks, which were then scanned and counted by an optical microscope of suitable magnification. By calculating the track density of registered tracks, the radon and radium concentrations along with exhalation rate of radon, were determined using required formulae. Results: The radon and radium concentration in various brands of cements found to vary from 333±9.9 to 506±13.3 Bq m-3 and from 3.7±0.1 to 5.6±0.2 Bq k g-1 while in various cementious finishing materials used in the construction, these were found to vary from 378±19.7 to 550±9.8 Bq m-3 and from 4.2±0.2 to 6.1±0.1 Bq Kg-1, respectively. Based on the data the mass and surface exhalation rates were also calculated Conclusion: The measurements indicate that there is marginal variation of the concentration of radium and radon in various brands of cements in India with lower levels in the cement samples having red oxide and higher levels in fly ash based cement

Evaluation of neutron shielding made of cement type material

International Nuclear Information System (INIS)

Seshimo, Takuya; Nagai, Takayuki; Onose, Atsushi; Takuma, Yasuhisa; Tanuma, Hiroyuki; Otagawa, Masaaki

1998-01-01

We prepared boron-containing cement and evaluated the characteristics of this new cement. This is the material of neutron shielding which is lighter than existing one. The quality we aimed is: H ≥ 0.025 g/cm 3 , B ≥ 0.065 g/cm 3 , density ≤ 1.70 g/cm 3 . We made test pieces changing water powder ratio (W/P), adding amount of air entraining agent, adding amount of water reducing agent, and time of vibration, and then, evaluated the characteristics. The measured parameters are the air content, mortar flow and homogeneity for cement mortar, homogeneity and compressive strength for hardened one. From the results of these tests, we confirmed the possibility of making neutron shielding that can satisfy the aimed quality using this boron-containing cement. After all, we established the method of making the neutron shielding, and this method was used in the construction of RETF. (author)

Evaluation of national cements for the conditioning of radioactive wastes

International Nuclear Information System (INIS)

Mallaupoma, M.; Soriano, A.; Rodriguez, G.; Cruz, W.

1996-01-01

The preliminary research studies carried out to implement the liquid radioactive waste conditioning by cementation are described. First of all, different kind of commercial cements in Peru are analyzed. In the first step, the analysis were made without using the radioactive material. The analyzed parameters were density, porosity, setting time and mechanical strength of a cement type called 'Atlas'. Samples of two geometries were used. One of them was a cylindrical sample (48mm diameter and 48mm height) and the another one was a prismatic sample (40x40x160mm). The results of the different kind of analysis are presented in this paper. (authors). 2 refs., 3 tabs

Effective medium of periodic fluid-solid composites

KAUST Repository

Mei, Jun

2012-05-24

An analytic solution of the effective mass density and bulk modulus of a periodic fluid-solid composite is obtained by using the multiple-scattering theory in the long-wavelength limit. It is shown that when the concentration of solid inclusions is high, the effective mass density is structure dependent and differs significantly from the leading-order dipole solution, whereas Wood\\'s formula is accurately valid, independently of the structures. Numerical evaluations from the analytic solution are shown to be in excellent agreement with finite-element simulations. In the vicinity of the tight-packing limit, the critical behavior of the effective mass density is also studied and it is independent of the lattice symmetry. © 2012 Europhysics Letters Association.

Growth of high-density ZnO nanorods on wood with enhanced photostability, flame retardancy and water repellency

Energy Technology Data Exchange (ETDEWEB)

Kong, Lizhuo; Tu, Kunkun; Guan, Hao [Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091 (China); Wang, Xiaoqing, E-mail: wangxq@caf.ac.cn [Research Institute of Forestry New Technology, Chinese Academy of Forestry, Beijing 100091 (China); Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091 (China)

2017-06-15

Highlights: • ZnO nanorod arrays were deposited on the wood surface via a hydrothermal process. • The assembled ZnO nanorod arrays greatly enhanced the photostability of wood. • The treated wood can sustain direct exposure to flame with only minor smoldering. • The ZnO-coated wood modified with stearic acid showed a superhydrophobic surface. - Abstract: Zinc oxide (ZnO) nanorod arrays were successfully assembled on the wood surface in situ via a two-step process consisting of formation of ZnO seeds and subsequent crystal growth under hydrothermal conditions at a low temperature. The morphology and crystalline structure of the formed ZnO nanorods were studied by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). Highly dense and uniform arrays of ZnO nanorods with well-defined hexagonal facets were generated on the wood surface by tuning the concentration of the ZnO growth solution during the hydrothermal treatment. Accelerated weathering tests indicated that the assembled ZnO nanorod arrays were highly protective against UV radiation and greatly enhanced the photostability of the coated wood. Meanwhile, the ZnO nanorod-coated wood can withstand continuous exposure to flame with only minor smoldering in contrast with the pristine wood catching fire easily and burning rapidly. Moreover, when further modified with low-surface-energy stearic acid, the ZnO nanorod decorated wood surface can be transformed into a superhydrophobic surface, with a water contact angle (CA) of ∼154°. Such ZnO nanorod-modified woods with enhanced photostability, flame retardancy and water repellency offer an interesting alternative to conventional wood preservation strategies, highlighting their potential applications in some novel wood products.

Growth of high-density ZnO nanorods on wood with enhanced photostability, flame retardancy and water repellency

International Nuclear Information System (INIS)

Kong, Lizhuo; Tu, Kunkun; Guan, Hao; Wang, Xiaoqing

2017-01-01

Highlights: • ZnO nanorod arrays were deposited on the wood surface via a hydrothermal process. • The assembled ZnO nanorod arrays greatly enhanced the photostability of wood. • The treated wood can sustain direct exposure to flame with only minor smoldering. • The ZnO-coated wood modified with stearic acid showed a superhydrophobic surface. - Abstract: Zinc oxide (ZnO) nanorod arrays were successfully assembled on the wood surface in situ via a two-step process consisting of formation of ZnO seeds and subsequent crystal growth under hydrothermal conditions at a low temperature. The morphology and crystalline structure of the formed ZnO nanorods were studied by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). Highly dense and uniform arrays of ZnO nanorods with well-defined hexagonal facets were generated on the wood surface by tuning the concentration of the ZnO growth solution during the hydrothermal treatment. Accelerated weathering tests indicated that the assembled ZnO nanorod arrays were highly protective against UV radiation and greatly enhanced the photostability of the coated wood. Meanwhile, the ZnO nanorod-coated wood can withstand continuous exposure to flame with only minor smoldering in contrast with the pristine wood catching fire easily and burning rapidly. Moreover, when further modified with low-surface-energy stearic acid, the ZnO nanorod decorated wood surface can be transformed into a superhydrophobic surface, with a water contact angle (CA) of ∼154°. Such ZnO nanorod-modified woods with enhanced photostability, flame retardancy and water repellency offer an interesting alternative to conventional wood preservation strategies, highlighting their potential applications in some novel wood products.

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

Azimuthally acoustic logging tool to evaluate cementing quality

International Nuclear Information System (INIS)

Lu, Junqiang; Ju, Xiaodong; Qiao, Wenxiao; Men, Baiyong; Wang, Ruijia; Wu, Jinping

2014-01-01

An azimuthally sensitive acoustic bond tool (AABT) uses a phased arc array transmitter that can provide directionally focused radiation. The acoustic sonde consists of a phased arc array transmitter and two monopole receivers, the spaces from the transmitter being 0.91 m and 1.52 m, respectively. The transmitter includes eight transducer sub-units. By controlling the high-voltage firing signal phase for each transmitter, the radiation energy of the phased arc array transducer can be focused in a single direction. Compared with conventional monopole and dipole transmitters, the new transmitter provides cement quality evaluation with azimuthal sensitivity, which is not possible with conventional cement bond log/variable density log tools. Laboratory measurements indicate that the directivity curves for the phased arc array and those computed theoretically are consistent and show good agreement. We acquire measurements from a laboratory cistern and from the field to validate the reliability and applicability of the AABT. Results indicate that the AABT accurately evaluates the azimuthal cement quality of case-cement interfaces by imaging the amplitude of the first-arrival wave. This tool visualizes the size, position and orientation of channeling and holes. In the case of good case-cement bonding, the AABT also evaluates the azimuthal cementing quality of the cement formation interface by imaging the amplitude of formation waves. (paper)

Wood formation from the base to the crown in Pinus radiata: gradients of tracheid wall thickness, wood density, radial growth rate and gene expression

Science.gov (United States)

Sheree Cato; Lisa McMillan; Lloyd Donaldson; Thomas Richardson; Craig Echt; Richard Gardner

2006-01-01

Wood formation was investigated at five heights along the bole for two unrelated trees of Pinus radiataBoth trees showed clear gradients in wood properties from the base to the crown. Cambial cells at the base of the tree were dividing 3.3-fold slower than those at the crown, while the average thickness of cell walls in wood was highest at the base....