Wood-cement Composites Research Articles

Morphological Approach for Nonlinear Flow and Heat Transfer in Complex Bio-Composite Material

ABSTRACTThe bio-based materials have experienced in recent years a relevant evolution in construction and for many building applications. Despite the efforts to develop new solutions to achieve the objectives of numerical characterizations, a few researches in this area have been carried out using a heterogeneous wood-cement composite. This study is based on a constructive approach using the finite volume method in order to generate a numerical model capable of reproducing the equivalent transfer properties of a wood-cement composite. The challenge is to understand, design, and control this multiphase inhomogeneous structure and predict transfers and flows within the community in order to achieve an optimal functionality. Experimental measurements and microscopic characterization using X-ray microtomography were performed to compare and demonstrate the method validation. The comparative results demonstrate a less than 10% deviation between the measurements and the simulations of the equivalent thermal properties. Thus, thermal conductivity and permeability, under different medium configurations, were characterized. Therefore, it was observed that these properties depend strongly on the porosity and the pore distribution in the continuous phase. Moreover, these two parameters are highly dependent on cement percentages in the structure.

Influence of the spruce strands hygroscopic behaviour on the performances of wood-cement composites

In wood wool cement composites, the influence of natural fibres is the main factor leading to the instability of the final product. During the manufacture, small variations in wood properties result in inhomogeneous density and strength of the boards. Among the accountable factors, the hygroscopic behaviour of the wood can deeply affect the cement hydration. However, the competitive water absorption mechanism between wood strands and cement is not fully understood. This paper will address the absorption behaviour of wood wool strands in combination with cement. A model for calculating the water to binder ratio of the paste in presence of wood is proposed and validated by NMR and isothermal calorimetry. Finally, the mechanical performances of the composites are tested for different water amounts, verifying the proposed model and defining the conditions for the optimal bending strength.

Suitability of sawdust from three tropical timbers for wood-cement composites

ABSTRACTConstruction material rising cost and global demand for economically-sustainable and environmentally-friendly building resources have necessitated the use of sawdust-cement composite. Wood constituents and cement incompatibility hinder its production and need careful selection of the timber. Sawdust suitability from Triplochiton scleroxylon, Entandrophragma cylindricum and Klainedoxa gabonensis for wood-cement composite was determined by identifying their chemical constituents and their composites’ physico-mechanical properties. T. scleroxylon recorded the minimum total extractive (6.12%), lignin (29.89%) and holocellulose (56.38%) and K. gabonensis the maximum (9.31, 31.59 and 57.5% respectively). Ash content was higher for T. scleroxylon (7.6%) but lower for K. gabonensis (1.53%). T. scleroxylon boards were stronger [Modulus of Elasticity (MOE) = 696.1 N/m2] and more moisture-resistant [Moisture Absorption (MA) = 8.8%] than E. cylindricum (MOE = 625.9 N/m2; MA = 9.5%). K. gabonensis boards crushed after manufacturing due to its incompatibility with cement. T. scleroxylon sawdust is suitable for wood-cement composites due to its more compatible chemical constituents (i.e., lower extractive, lignin, holocellulose contents and more ash) and its boards’ excellent physico-mechanical properties than those for the other timbers. Its sawdust-cement composites could be utilized for cladding and walling. The use of sawdust would increase green building resource base and reduce environmental pollution.

Chromated copper arsenate timber: A review of products, leachate studies and recycling

Abstract Large volumes of chromated copper arsenate (CCA)-treated wood are disposed of in lined and un-lined landfills across the world. Studies regarding the disposal and reuse of CCA-treated timber date back to the 1980s. This paper provides a comprehensive overview of the research undertaken regarding reconstituted chromated copper arsenate-treated timber products, and considers the relevant health issues and disposal techniques, such as incineration and thermochemical conversion, as well as long-term solutions for the managing of chromated copper arsenate-treated-waste wood. The results from reviewing the literature regarding reconstituted timber products consisting of CC-treated timber such as particle board, cement-bonded particle board, flake board, remediated wood composites, wood-plastic composites, and wood-cement composites revealed that products such as particle board, wood-plastic composites and flake board composed of CCA-treated timber show considerable promise. Further research is required to determine the optimum percentage of CCA-treated timber in wood-plastic composites to minimize leaching while attaining suitable physical and mechanical performance, and to evaluate the durability of reconstituted chromated copper arsenate timber products via severe accelerated aging tests. Several CCA-waste wood disposal methods were investigated in the form of extraction and destruction techniques including thermochemical conversion (pyrolysis, gasification), incineration, co-incineration and combustion. Such management techniques demonstrate promising, feasible, future solutions providing the ability to trap arsenic gas, recover metals, and create secondary energy forms. However, more research is required, especially regarding resultant arsenic compounds and their volatile behaviours. Industries that create and sell chromated copper arsenate-treated wood products are encouraged to follow the United States Environmental Protection Agency leachate testing procedures (Methods 1314 and 1315, published in 2013), since these methods are more accurate at evaluating the leaching behaviour during their lifetime, and various disposal scenarios that reflect differing pH values and liquid to solid ratios.

Utilization of wastes from medium density fiberboards production as an aggregate for lightweight cement composite

The possibility of recycling waste from medium density fiberboard (MDF) production into wood-cement composites was evaluated. A large quantity of lignocellulosic wastes is generated worldwide from various sources, including wood and furniture industries, leading to environmental concerns. Medium density fiberboard (MDF) is an engineered wood product, which is made from wood fibers (mainly form coniferous trees) with wax and a resin binder. This paper presents an experimental study which investigated the potential utilization of medium density fiberboard wastes (MDFW) for producing lightweight insulation concrete. The wastes were screened on #8 mm sieve to exlude big irregular elements which could negatively affect compaction and strength properties. All lignocellulosic substrates have detrimental effects on cement setting so different techniques were applied to offset the retarding effect of compounds like sugar and tannin present in the bio-based particles before mixing the wastes with cement. One type of cement CEM I 42,5 R was used in the experiment. Flexural strength, compressive strength in air-dry and wet states, and water absorption of lightweight concrete were tested. Compressive strength ranging from 0,5 to 5.3 MPa was obtained depending on the material used for the initial impregnation of MDFW fibers.

Particle size and lime addiction on properties of wood-cement composites produced by the method of densification by vibro compaction

ABSTRACT: This paper aimed to evaluate the effects of particle size and the use of lime as a pretreatment of Pinus spp wood particles on the production of wood-cement composites by vibro-compaction densification. Specimens for internal bond and static bending were produced with two different particle sizes: G1, particles that pass through a 4mm screen and were retained at 2mm screen, and G2, particles that pass through a 2mm screen and were retained at 0.84mm screen. The use of lime was also tested in two different methods as pretreatment of wood particles: carbonatation of wood particles before being used in the composite mixture; and addition of hydrated lime directly to the composite mixture. Use of larger particles (G1) presented higher values of internal bond and MOR than composites produced with smaller particles (G2). About the pretreatments, the use of hydrated lime resulted in composites with higher density and better internal bond.

Mechanical Performance of CO2 and Autoclave Cured Date Palm Fiber Reinforced eco-mortar Composites

Using nature waste fibers in construction industries had shown important character "environmental friendly" which paid a great interest around the world. The aim of this paper was to investigate the suitability of agriculture waste date palm fibers as lignocellulosic materials for the production of wood-cement composite, in addition to enhance their compatibility with cement using accelerated curing like carbonation or autoclave. Three percentages of date palm fibers were used (2, 6, and 10)% by weight of cement in cement composites specimens. Compressive, flexural and direct tension strengths were examined as strength properties and X-ray diffraction (XRD) as microstructure properties. The results show that carbonation curing was the most effective curing for compressive strength property while autoclave curing leads to better performance in flexural strengths. Curing type effects on direct tension property were fluctuated. This could be attributed to the variation in cellulose fiber roles with respect to each property evaluated. X-ray diffraction confirmed that CO2-curing led to increased CaCO3 content compared with autoclaved composites.

Influence of Particle Size and Soak Conditions of the Species <i>Simarouba amara</i> on Cement-Wood Composites

The purpose of this work was to produce a mix design rarely reported in the literature on wood-cement composites, i.e., 1:1:0.5 (cement:wood:water). This design was achieved by using CP IV-32 RS cement and adding 4% of ferric chloride additive plus fibers of the species Simarouba amara (paparaúba) retained on ASTM 7 and ASTM 10 sieves. Before mixing the fibers into the cement paste, they were presoaked for 15 minutes to between 84% to 136% of their mass. In these conditions, all the heat of hydration tests presented low inhibition. Panels measuring 300 x 450 x 25 mm were prepared, and the values of compressive and flexural strength of the composite after 28 days showed no significant differences with respect to soak, but the effect of particle size was significant. These results indicate that more fiber can be added in the mix design of this cement-wood composite without changing its mechanical strength, controlling only the presoak conditions.

Wood cement composites reinforced with polypropylene fibre

Wood cement composites reinforced with polypropylene fibre

Effects of Two Types of Waste Wood Species on the Hydration Characteristic of Portland Cement

Despite much work on wood-cement composites, effects of wood species on the hydration of cements remain unclear until now. Thus, we herein investigated systematically effects of two typical wood species wastes on the hydration of Portland cement in this work. It was found that adding the poplar flour prominently affects the formation of the calcium silicate hydrate gel (C-S-H gel) delaying the hydration process, while the Chinese fir flour hardly retards the process due to different components. Compared with the neat cement, addition of both wood flours makes it easier to generate the ettringite. Besides, another important hydration product, calcium hydroxide Ca(OH)2, requires much longer time to form in the presence of both wood flours during hydration relative to the neat cement, e.g. nearly double time for the poplar-filled cement system. The findings provide useful information for extending the potential application of wood flours waste in cement composites.

Vibro-dynamic compression processing of low-density wood-cement composites

This work evaluates physical and mechanical characteristics of low-density wood-cement composites manufactured in a new method on a laboratory scale. The samples were molded with two different commercially available brands of Portland cement and wood particles generated from branches and trunks of pine (Pinus spp.) trees. The wooden particles were pre-treated with a calcium hydroxide suspension. The used Portland cements (CP II-Z) were both modified with a super-plasticizer additive and a booster grip. The composites were molded by vibro-dynamic compression into cylindrical and prismatic sample composites without the application of piezzo-metric action. After 28 days of air curing, density, axial compressive strength and perpendicular tensile strength of the samples were measured. Both brands of Portland cement provided proper agglutination of the pre-treated wooden particles. The wood-cement composites were well compressible under the vibro-dynamic procedure—conferring a low density to the final wood-cement composite with adequate physical and mechanical properties. The composites met and confirmed the relevant standard performances.

Influence of wood treatments on mechanical properties of wood–cement composites and of Populus Euroamericana wood fibers

Wood–cement composites are interesting materials for structural and isolation purposes. Dimensional stability, economic factors and resistance to environmental degradation are features that can be exploited for housing components. The main inconvenient affecting its manufacture is the incompatibility between wood and cement, caused by setting inhibitory substances present in woods. Wood treatments are multivariable processes required for the appropriate cement setting reaction on wood surfaces. Treatment conditions affect the mechanical properties of the resulting composites. This work evaluates the simultaneous influence of the variables ruling three widely used wood treatments – water extraction, degradation by alkaline hydrolysis and retention of inhibitory substances – on the mechanical properties of wood fibers and of resulting wood–cement composites. Populus Euroamericana wood fibers and Portland cement were selected as case materials. The alkaline hydrolysis was found as the most effective treatment for the suppression of inhibitory substances and the highest decrease on mechanical properties of resulting composites. Empirical relationships describing the dependence of the compressive modulus of elasticity and compression strength of wood–cement composites with the wood treatment variables are presented.

Влияние направления формования и нагружения на прочностные характеристики строительных блоков из древесно-цементного композита

Влияние направления формования и нагружения на прочностные характеристики строительных блоков из древесно-цементного композита

Mechanical properties of hierarchically structured wood–cement composites

Wood wool cement composites (WWCC) are widely used materials constituted of wood wool and Portland cement. The material presents excellent mechanical, chemical and biological properties. However, the understanding of its mechanical behavior is rather limited. In this contribution, a hierarchically structured model is presented to describe the mechanical behavior of WWCC under compressive stress. The material is modeled as 3D rigid open cellular structured material, 2D randomly oriented triple laminated material and particulated+fibrous material in the cm, mm and μm scales, respectively. The outcome of the model is a set of mathematical expressions permitting to predict the stress–strain behavior of the material in two cases: wood strands parallel and perpendicularly oriented to the stress direction. Mechanistically, the model predicts failure by buckling at the mesoscale. A statistical experimental work is included and used to validate the model.

Wood-cement composites using suitable mix of sawdust and fibres from veins of palm tree leaves

Some tropical wood species are currently used in wood work and generating an important quantity of wood waste in Benin, Western Africa. Recycling these wastes through building material is a way to solve environmental challenges, but the wood resources are not inexhaustible and vegetable fibers such as Eleais guineensis fibers, obtained from veins of palm tree leaves are available in nature. The main concern of this study is to determine the most suitable mixes of E. guineensis fibers and five West African hardwood species namely Diospyros mespiliformis, Khaya grandifoliola, Tectona grandis, Pterocarpus erinaceus and Isoberlina doka for wood-cement composites. The compatibility with cement of mixes of fibers and sawdust is studied based on measurements of cement heat hydration and compatibility indices. The tensile and compressive strengths of the composites were determined to evaluate the potential of the mixes. The results show that the woody residues inhibit the hydration reactions of cement and greatly more when containing E. guineensis fibers. Hydration tests indicated that all the mixes could be rated as having moderate to good compatibility with cement after hot water treatment. Mechanical tests showed that the mixes containing Isoberlina doka, Tectona grandis and Khaya grandifoliola sawdust provided the highest mechanical strengths. Key words: Vegetable fibers, sawdust, compatibility, wood-cement composites, mechanical strengths.

PAINÉIS CIMENTO-MADEIRA DE Eucalyptus saligna COM DIFERENTES ADITIVOS QUÍMICOS E MÉTODOS DE FORMAÇÃO

Este trabalho teve como objetivo avaliar o potencial de uso de diferentes aditivos químicos e métodos de formação na produção de compósitos cimento-madeira com clone de Eucalyptus saligna. Utilizou-se o cimento Portland tipo CP II-Z, como aglutinante mineral, e cloreto de cálcio (CaCl2) e cloreto de magnésio (MgCl2),como aceleradores de cura do cimento. Os painéis cimento-madeira foram produzidos pelo método de prensagem na prensa de pratos de 50,5 x 38,5 x1,5 cm, e pelo método de adensamento por vibrocompactação em dimensões de 35 x 7 x1,5 cm. Os painéis foram formados com densidade nominal de 1 g/cm³ e relação cimento:madeira de 2,75:1. Com base nos resultados, pode-se concluir que: (I) os testes de hidratação mostraram que a madeira é compatível com o cimento Portland tipo II; (II) o uso de cloreto de cálcio e de magnésio na proporção de 3% em relação à massa do cimento proporcionou incremento nas propriedades físicas e mecânicas dos painéis produzidos pelos dois métodos de formação avaliados; (III) os painéis produzidos pelo método de adensamento por vibrocompactação apresentaram menor densidade média, maior estabilidade dimensional e melhor tração perpendicular do que os painéis produzidos pelo método tradicional de prensa de pratos.Palavras-chave: Compósito cimento-madeira; vibro compactação; aceleradores de cura. AbstractWood-cement boards of Eucalyptus saligna with different chemical additives and methods of formation. The aim of this work was evaluate the potential use of different chemical additives and methods of formation for wood-cement composites with Eucalyptus saligna clones. Portland cement type II-Z was used as mineral bonding and Calcium chloride (CaCl2) and Magnesium chloride (MgCl2) as accelerator of the cement hydration. The wood-cement panels were produced by the cold press method with dimensions of 50.5 x 38.5 x1.5 cm, and by vibro-compaction densification with 35 x 7 x 1.5 cm. Both methods used a nominal density of 1.0 g/cm3 and wood: cement ratio of 1:2.75. Main results: (I) Hydration tests showed that E. saligna wood is compatible with Portland cement type II; (II) Use of Calcium and magnesium chlorides at 3% in relation of the cement dry weight improve physical and mechanical properties of wood-cement composites produced by studied methods; (III) Composites produced by vibro-compaction densification presented lower density, higher dimensional stability and higher internal bond than composites produced by the traditional cold press method.Keywords: Cement-wood composites; vibro-compaction; chemical accelerators.

Wood-Cement Composites from Wastes of Pinus Sp. Wood: Effect of Particles Treatment

The aim of this research was to produce and evaluate mechanical performance in compression parallel to the grain for composites made with wastes from Pinus sp. and Portland cement. To obtain the composites were used treated and untreated wood particles, average size 1.7mm, and Portland cement-II-E-32, determining a ratio for cement/wood/water of 1: 0.21: 0.6. Treatment of particles was based on thermal bath in water for a period of 6 hours. Effect of treatment on density and mechanical properties of these composites was analyzed, according to NBR 7215:1996. Results showed that inclusion of treated wood particles in manufacture of wood-cement composite was significant in all properties investigated, by reducing density (7%); increasing modulus of elasticity (126%) and compressive strength (70%). Large gains in these properties demonstrate the feasibility of wood-cement composites manufacture.

Physical and Mechanical Properties of Wood-Cement Composite with Lignocellulosic Grading Waste Variation

This research aimed verifies, with the aid of the analysis of variance (ANOVA), the influence of particles size of <i>Eucalyptus grandis</i> wastes in density and modulus of elasticity and strength modulus in compression of wood-cement composites. For this study was performed production and characterization of specimens, using portland cement, water and particle waste of <i>Eucalyptus</i> wood species, classified into sieves 10, 20, 32 and 60 mesh. The results of ANOVA showed significant differences in particle size, while samples with smaller particles had higher densities and lower mechanical performances. The composites studied have fully capable of being used as paving blocks, pavers or closure without the need for structural performance panels.

Разработка метода оптического анализа изображения поверхности образца древесно-цементного композита

Barking waste at a pulp and paper mill can be used for construction materials fabrication. The paper presents principles of an estimation technique based on image analysis of the surface for assessing wood-cement composites properties. Images of side faces of wood-cement composites samples obtained under certain lighting parameters are characterized by optical density anisotropy. Analysis of fractal dimensions of images of top, bottom, and side faces surfaces shows that their structure depends on the molding process of a wood-cement composite. The results obtained allow us to hope that a method of nondestructive testing the sample strength of such materials could be developed in future.

Properties of Plastic Bonded Agricultural – Waste Composites, I: Charcoal and Wood-Dust Separately Bonded Composites

Eleven (11) composites, are unfilled and five each filled with varying contents of charcoal and wood dust separating bonded with melted spent thermoplastics have been compounded and their compressive strength, density, specific gravity, percentage shrinkage and percentage absorption determined.Composite density ranges (0.83-0.94)g/cm 3 , compressive strength from (6.92-16.14)n/mm 2 , percentage shrinkage from (1.01-4.76)% and percentage water absorption from (1.75-15.75)%. These results suggest that these composites (i) meet the allowable American standard for test and measurement (ASTM) for ceramic floor and wall tiles in compressor strength (0.2-22.1)minimum, % shrinkage (maximum 15%) and water absorption (maximum 16%) (ii)are appreciably strong compare to the gmelina-wood/cement composite and (iii) if comprehensively examined, composites may be useful in the building industry for the manufacture of tiles and boards and even compete favorably with the wood cement composites. Keywords: Compressive strength, % shrinkage, % absorption, thermoplastic,tiles. I. Introduction The reinforcement of inorganic matrices for improved structural integrity with linigocellulose fluids materials is an old option. Inorganic builders such as Portland cement have been used in building elements. Example of the different types of inorganic bonded wood composite industrially produced are magnesium bonded composite panel (1,2). They are used as particle partitioning, cladding, wall lining and paneling and roofing of floor base (3-5) The use of cement builder in the production of particle boards has aroused interest lately probably because of the shortage and increase in the price of synthetic resin and the desire of develop boards that are suitable foe the exterior applications. The needed raw materials (cement and wood) are readily available in developing countries and the production technology is relatively simple. The cement bonded particle boards is reported (2, 6-8) to have better resistance to impact loading when compared with asbestos board stiffer than the unbound with a bond strength that increase progressively with period of exposure to structural weathering. One of the many problems with cement bonded particle is that of which relates to the weight of the board. Commercially, the board is manufactured within the density range of 1100-1300kg/m 3 and with cement wood ratios ranging between 2.75 -3.00 cement to 1.00 of wood on weight basis (9). The large quality of cement per unit weight of wood employed in the board manufacture makes the resultant board to be heavy. It has been noted that the characteristically high density of the board is a possible limitation to the boards use particular in the areas where weight saving is essential. Deppe (10) noted the need for research effort directed towards finding ways of reducing density of the board while at the same time improving the strength of the board.This need is the aim of the present work. The sale of pure water in plastic sachets without effective management of the sachet after the consumption of the water contains has resulted in environmental pollution caused by the non-biodegradable spent purer water sachet particularly in our cities in this country. In an attempt to control the menace, the spent sachet has been used as a binder in the production of particle boards separately consisting of charcoal and wood dust. The compressive strength, % absorption and % shrinkage of the composites are reported in this write up. EXPERIMENTAL Materials spent pure sachet were collected from restaurants, washed and sun dried. Filters: (a) Charcoal was bought at the Erekesan market Akure, washed, sun dried, crushed and sieved with endecotte sieve into an appropriate particle size and stored at 105