Wood-cement Boards Research Articles

Study of the Effect of Cedar Sawdust Content on Physical and Mechanical Properties of Cement Boards.

The growing demand for sustainable building materials, amid escalating costs, has spurred interest in alternative solutions such as wood cement composites. This study explores the feasibility of producing wood cement boards (WCBs) using locally sourced cedar sawdust as a reinforcing agent. Boards with a thickness of 10 mm and a target density of 1200 kg/m3 were manufactured under pressures ranging from 2 to 6 MPa for 24 h. Cedar sawdust, used as raw and untreated material, was incorporated into the mixture as a partial substitute for cement in varying proportions, ranging from 10% to 25% (by weight). The WCBs were cured for 28 days under ambient conditions. Physical properties including density, water absorption (WA), and thickness swelling (TS) were assessed, along with mechanical properties through flexural tests. The results showed that increasing cedar sawdust content decreased both density and mechanical performance while increasing WA and TS. Microstructural analysis (SEM and EDS) revealed significant porosity at higher sawdust contents, while lower contents had better matrix-reinforcement cohesion. Additionally, substantial levels of calcium and silicon were detected on the sawdust surface, indicating stabilized cement hydration products. These findings, supported by thermal (TGA and DSC) and FTIR analyses, clearly demonstrate that cement boards with 10% cedar sawdust exhibit favorable properties for non-structural applications, such as wall and partition cladding.

A preliminary study of mechanical treatments’ effect on the reactivation of hydrated cement paste

More than 4.4 billion metric tons of cement were produced in 2021 [1], making it one of the most common building materials. Unfortunately, excessive cement use brings up several environmental concerns, one being the enormous volumes of CO2e (carbon dioxide equivalent) created as a by-product. CO2e is a standard unit for measuring carbon footprint and can be calculated for all greenhouse gases using global warming potential. Reducing CO2 and other greenhouse gas emissions is crucial in modern cement manufacturing, as 0.9 kg of CO2e is produced for every kg of cement. Cement manufacturing contributed by releasing 3.96 Gt of CO2e into the atmosphere in 2021. This issue is often remedied using recycled materials in the fresh concrete mix as supplementary or pozzolanic additives. Some researchers have focused on regaining the activity of hydrated cement paste by grinding and thermally activating it [2–5], but a low-strength binder would also work for many applications. A low-strength binder recovered with as little energy as possible (only grinding, no heat treatment) could be considered a more sustainable and less energy-intensive way of recovery of the cement binder matrix. This study investigated a technique for recycling hydrated cement paste by mechanical treatment to disintegrate the hydrated cement conglomerate to reveal the unhydrated cement particles [6] that can be used as a recovered cementitious binder from processing waste from the production of wood-cement boards. Processing waste is defined as cement particles containing hydrated and unhydrated cement [7] and spruce wood fibres. The partly hydrated cement in the waste stream was mechanically processed in a planetary mill to reactivate it and restore its cementitious characteristics. The binder was characterized by density and mechanical compressive strength.

Microcrystalline cellulose addition effects on the properties of wood cement boards

The study investigates the performance of microcrystalline cellulose (MCC) as reinforcer in cementitious wood particle products. The wood cement boards were produced with various MCC amounts, up to 30 wt % based on wood particle weight. Physical, thermal and mechanical properties of MCC added wood cement boards were investigated and compared with conventional wood cement boards. The water absorption and shrinkage of cement panels decreased at low MCC additions, but increased at high rates of MCC. The highest values of the MOR and IB of the wood cement boards were observed at 5% and 10% MCC content, respectively. When used above this ratio, the MOR values were significantly reduced. The dispersion effect of MCC depending its ratio in cement matrix was observed with scanning electron microscope. Although the possibility of overlapping of wood component (lignin) and cement hydrate [Ca(OH)2] signals due to the high decomposition temperature of lignin challenged the determination of Ca(OH)2 amount, one of the cement hydration products, TGA/DTG results demonstrated that as the MCC content in the wood cement boards increased, the decomposition amount of Ca(OH)2 increased. This indicates that mcc improved the cement hydration, compared to spruce wood. In terms of DSC results, the addition of MCC to the wood cement boards lowered the temperature and increased the enthalpy and peak height.

Wood–cement boards with addition of coconut husk

ABSTRACT The present work evaluates the production of wood–cement particleboards (WCBs) with addition of coconut-husk fibers. Trees of a Eucalyptus urophylla × Eucalyptus grandis hybrid were used as wood source. Boards were produced with addition of five coconut-fiber levels (0%, 10%, 20%, 30%, 40% and 50%) to replace the original wood, in a completely randomized design. From each board, specimens were taken to perform physical–mechanical tests (density, water absorption, thickness swelling, static bending, compression strength, and internal bond strength). The chemical characterization of the coconut fiber – in particular the total amount of extractives – in cold and hot water and an organic solvent, along with determination of lignin, holocellulose and ash amounts. The results showed that the addition of coconut fibers significantly affected the physical–mechanical properties of the boards. For the physical properties, the addition of coconut fibers improved the dimensional stability with the respective decrease in water absorption and thickness swelling. For mechanical properties, a decrease in the MOR and MOE was observed as the percentage of coconut fibers increased, most likely due to a poor interaction between the particles and the cementitious matrix. The resulting WCBs were suitable for nonstructural and indoor uses.

DIMENSIONAL STABILITY AND TENSILE STRENGTH OF WOOD PLASTIC COMPOSITE FORMED WITH HIGHER PLASTIC CONTENT

This study investigated the dimensional stability and strength properties of plastic bonded composites produced from wood waste particles and polyethylene using extruder. The composites were produced from wood species such as such as: Triplochiton scleroxylon, Terminalia superba and Gmelina arborea at a mixing proportion of 60:40 (plastic/wood) on a weight by weight basis. Evaluation of properties was carried out in accordance with the American Standard Testing Methods of 570 and 790 to determine the dimensional stability and strength properties of the composites. The results of findings revealed that water absorption and thickness swelling of the wood composites ranged from 10.08% to 15.36% and 4.33% to 5.58% respectively after 24hours and 48hours immersion in water. Tensile strength also ranged between 29.4MPa and 45.6MPa. Composite board made from T. superba wood particles had the lowest significant water absorption (10.08%), thickness swelling (4.33%) and highest significant tensile strength (45.6MPa) compared to composites produced from G. arborea and T. scleroxylon wood particles. It was observed that high density wood species exhibit lower water intake, lower thickness swelling and higher tensile strength, while the contrary is the case for lower density wood species. In conclusion, the three tree species used for the study could be recommended for the production of wood composite like particle board, fibre board, wood cement boards and others.

Cement boards reinforced with wood sawdust: an option for sustainable construction

Ochroma pyramidale is a fast-growing forest species with low-density wood. The present study had the goal to assess the effect of extractive removal on the performance of the species for producing wood-cement boards (WCB). Wood particles were submitted to three types of treatment for extractives removal: cold water, hot water and sodium hydroxide (NaOH). An entirely randomized design with four treatments was established, respectively, T1—control treatment, T2—cold water, T3—hot water and T4—NaOH, with 4 replicates (boards) per experimental treatment, to assess the effect of extractives removal on the boards’ physical and mechanical properties. Wood/cement ratio = 1:5, water/cement ratio = 1:2 and 4% CaCl2 as additive based on dry mass of cement were used. The following WCB properties were evaluated: density, compaction ratio; water absorption and thickness swelling after 2, 24 and 72 h of water immersion; and mechanical strength during static bending (moduli of elasticity and rupture). The results showed there was no need for wood particle treatment, since no improvement of the boards’ physical–mechanical properties was achieved by previous application of cold or hot water or NaOH on the particles. Water absorption and thickness swelling were lower than the levels reported in the literature and minimum values specified by WCB factories. Despite having weaker mechanical properties than those required for structural uses, wood from Ochroma pyramidale can be employed in the production of boards designed for use in moist environments but not having structural importance, such as for partitions, walls, tile flooring and exterior siding.

Enhanced Resistance to Fire of the Bark-Based Panels Bonded with Clay

The aim of this study was to investigate the flammability of ecologically friendly, 100% natural larch and poplar bark-based panels bonded with clay. The clay acted as a fire retardant, and it improved the fire resistance of the boards by 12–15% for the surface and 27–39% for the edge of the testing specimens. The thermal conductivity was also analyzed. Although the panels had a density ranging from 600 to 900 kg/m3, thermal conductivity for the panel with a density of 600 kg/m3 was excellent, and it was comparable to lightweight insulation panels with much lower densities. Besides that, the advantage of the bark clay boards, as an insulation material, is mostly in an accumulative capacity similar to wood cement boards, and it can significantly improve the climatic stability of indoor spaces that have low ventilation rates. Bark boards with clay, similar to wood cement composites (wood wool cement composites and wood particle cement composites), have low mechanical properties and elasticity. Therefore, there their use is limited to non-structural paneling applications. These ecologically friendly, 100% natural and recyclable composites can be mostly used with respect to their thermal insulation, acoustics and fire resistance properties.

AN EXPERIMENTAL RESEARCH REGARDING THE OPTIMUM COMPOSITION FOR WOOD SLAG BOARDS

Wood slag boards (WSB) belong to the group of composites formed on the basis of mineral binders (cement, gypsum, blast-slag, etc.). They are multi-componential systems consisting of wood particles, slag-alkaline and mineralizator. The physico-mechanical properties of WSB completely answer the standard requirements valid for high-density wood-cement boards and therefore can be used as a competitive building material. The economic relevancy of their production is grounded in providing building industry with high-quality and at the same time cheap materials, as well as in utilizing scrap materials which would otherwise pollute the environment (blast slag and scrap wood). The optimizing of the mass parts of the components of WSB is a very important problem both from technological and economical point of view. The success in solving the optimizing problem depends to a great degree on the choice of method. This is way a planned experiment is applied, based on the simplex method for multicomponent system with preliminarily determined limits of calculation of the factors. With the help of specialized computer software, the optimum quantity of the components is determined through graphically presented optimum areas

Determination of the physical and mechanical properties of wood-cement boards produced with Pinus spp and pozzolans waste

The objective of this research was to evaluate the physical-mechanical properties of wood-cement boards produced with waste particles of Pinus spp. and sufficient levels of pozzolans to assimilate all Ca(OH)2 pro-duced during the hydration reactions of Portland cement. The pozzolans used were: silica fume, metakaolin, rice husk ash, and calcined ceramic waste. The values of the pozzolans were determined based on the theo-retical determination of the Ca(OH)2 content produced by the hydration reactions of Portland cement. The pozzolanic activity index was determined by the modified Chapelle test. The boards were produced through cold compression, and the test specimens were produced and tested for physical and mechanical properties at 28/91 days of curing. The minimum values employed in the Bison® commercial process were used as a reference for the physical-mechanical characterization. The boards produced presented good physical-me-chanical properties even with high levels of replacement of cement by pozzolans. These properties were sim-ilar to the ones presented by the reference boards, despite the significant reduction in the specific mass of the prototype boards, which demonstrates the technological possibility of the use of these materials in the produc-tion of wood-cement boards

PHYSICAL AND MECHANICAL PROPERTIES OF ORIENTED WOOD-CEMENT BOARDS PRODUCED WITH FIVE EUCALYPTUS SPECIES

This study aimed to manufacture oriented wood-cement boards using five Eucalyptus species and mixture between then, to compare the effect of the particles orientation, and to evaluate the physical and mechanical properties according to competent standards. The species studied were: Eucalyptus benthamii, Eucalyptus dunni, Eucalyptus grandis, Eucalyptus saligna, Eucalyptus urograndis the mixture between them and the Pinus taeda as control. The bonding agent employed was commercial grade Portland cement types CP II-Z-32R. The panels had dimensions of 48 x 48 x 1.2 cm and nominal specific mass of 1.2 g/cm³. The cement/wood/water mass ratio used was 2.5:1:1 and 2% of CaCl2 by weight of cement was used as an additive. The orientation of strands did not influence the dimensional stability properties. All boards had very low IB strength, being that, none treatments reached the requirements to internal bond of competent standards. The MOR and MOE results indicated that species mixture can be obtained boards with properties similar to pure species. In general, the boards showed low mechanical strength what can be attributed to particles geometry and wood-cement ratio. The wood of Eucalyptus species presents potential for use in cement-wood panels.

Cement type composite panels manufactured using paper mill sludge as filler

The aim of this study was to evaluate some physical and mechanical properties of the paper mill (PMS) and spruce planer shaving added cement boards. Also the effect of sludge type in consequence of waste water treatment technique on properties of wood-cement boards (WCB) was investigated. The wood/cement ratios were used as 1/3, based on the oven dry weight for the WCB manufacture. PMS was used up to 20% wt of total composite based on organic (wood) and inorganic (cement) amounts. Black sludge has shown more improvement than grey sludge on properties of WCBs, which indicates the anaerobic waste treatment technique is more effective for additive in WCB. The modulus of rupture and elasticity values of the WCBs with 5% of grey sludge, 5% and 10% of mixture of grey and black sludge were acceptable limits according to EN 634-2 standard. The mechanical strengths of all WCBs with black sludge were found above the specified EN standard. This suggests that PMS depending on sludge type may be used up to 20% wt of total composite weight for the commercial production of WCBs, which could expand the raw material base for this panel product.

Effects of CaCl2 and NaHCO3 on the physical and mechanical properties of Dhaincha (Sesbania aculeata) cement-bonded particleboard

Laboratory size (30.00 × 20.00 cm2) wood–cement boards with a thickness of 14 cm were produced using wood particles of dhaincha (Sesbania aculeate). The effects of cement setting accelerator calcium chloride (CaCl2) and combination of CaCl2 and sodium hydrogen carbonate (NaHCO3) on board properties were examined. The highest MOR and MOE values of the board were obtained from boards containing combination of CaCl2 and NaHCO3 as cement setting accelerator at a wood–cement ratio of 1:2.2. The thickness swelling values of boards were improved by using CaCl2 and NaHCO3 as cement setting accelerator compared to boards with no accelerator and only CaCl2 accelerator. This suggests that CaCl2 and NaHCO3 contributed to better particle-to-particle contact as a result of improved bonding ability with cement. The properties of certain boards are comparable to those of boards made from other raw materials. It is concluded that dhaincha with cement setting accelerator can be an alternative source to produce cement board with satisfactory properties.

Microwave Electromagnetic Filed and Temperature Distribution in a Multilayered Wood-Cement Board

Microwave Electromagnetic Filed and Temperature Distribution in a Multilayered Wood-Cement Board The aim of this work was theoretical considerations of a multi-layer structure and estimation of some properties of previously designed and prepared modified wood-cement boards. These were enriched by carbon powder as electric admixture to gain a high damping of electromagnetic radiation in microwave frequency region. The dissipated power and temperature assessment based on the heat and electromagnetic wave propagation in case of perpendicular incident radiation are presented. As a practical criteria of the shielding effectiveness —the drop of the temperature measured behind an irradiated multilayered shield was utilized.

EVALUATION OF USING MIDRIBS OF DATE PALM FRONDS AS A RAW MATERIAL FOR WOOD-CEMENT COMPOSITE PANELS INDUSTRY IN SAUDI ARABIA

This study was carried out in 2010 to investigate the suitability of date palm midribs (Phoenix dactelifera L.) as a lignocellulosic material for the production of wood-cement composite panels, in addition to enhancement their compatibility with cement using various pretreatments and chemical additives. Materials used for this study were midribs of fronds of different date palm varieties available in Saudi Arabia and Portland cement (Type I) manufactured by Yammama Cement Company. To achieve this aim, hydration tests of net cement and date palm-cement mixture were carried out using a 2-litter Dewar flask. The suitability of date palm for this industry was made according to inhibitory index (I) and compatibility factor (C ) which A were calculated from the hydration data. The results showed that under untreated condition, date palm particles are incompatible with cement and were classified as unsuitable for making wood-cement boards. Using of cold or hot water extraction for date palm materials resulted in an enhancement in their compatibility with cement. However, date palm can be reclassified as suitable under limited conditions for making wood-cement boards only by using hot water extraction. Addition of 3% CaCl to untreated date palm particles resulted in 2 reclassified it to suitable under limited conditions (T value was 54.23°C and C value was 75.73%). These max A results suggested that date palm midribs can be used to produce wood-cement panels either after extraction by hot water or addition of 3% CaCl as an accelerator to date palm-cement mixture. 2

Shielding of electromagnetic radiation by using wood-cement boards modified with carbon in microwave frequency band

The paper focuses on the development of carbon-modified wood-cement boards made of wood-wool for the purpose of shielding electro-magnetic radiation in the microwave frequency band. Powder coal was used as the electric conductive admixture to increase electric conductivity of wood-cement boards, and thus also total insertion loss. Increasing the concentration of carbon up to 25 wt% resulted in considerable rise of electric conductivity by 7 orders. The total insertion loss is directly proportional to thickness of the wood-cement board.

PRODUCTION AND PROPERTIES OF A MEDIUM DENSITY WOOD-CEMENT BOARDS PRODUCED WITH ORIENTED STRANDS AND SILICA FUME

Wood-cement board (WCB) is a panel product that has the advantages of inorganic and organic materials. However, the main problems affecting the manufacture and use of WCB are the inhibitory effects of wood on the setting of cement and the high specific gravity of the final product. This paper examines the potential of strand orientation and the use of silica fume (SiO2) to facilitate the production of a medium density WCB from Pinus taeda. Oriented wood-cement boards (OWCB) were manufactured with wood/cement (w/w) ratio of 1:1, specific gravity 850 kg/m3; and SiO2 content as cement replacement of 0%, 10% and 20%. The OWCB were tested for static bending (MOR and MOE) properties in parallel (//) and perpendicular (^) directions; internal bond (IB); compression strength parallel to surface (CP); thickness swelling (TS) and water absorption (WA). The results showed that replacement of cement with 10% of SiO2, increased MOE (//), MOR (//) and CP and, decreased WA and TS, and most importantly eliminated the inhibitory effect of wood on cement setting. The principle of strand orientation was effective to produce boards with anisotropy in the flexural properties ranging form 2.1 to 2.8 for MOR and 2.6 to 3.8 for MOE. However, boards had very low IB strength and this shortcoming must be addressed in future research

Manufacture of wood-cement boards VIII: cement-hardening inhibitory compounds of keyaki (Japanese zelkova, Zelkova serrata)

To isolate and identify the cement-hardening inhibitory components of keyaki (Japanese zelkova, Zelkova serrata Makino), methanol extractives containing inhibitory components were fractionated by successive organic solvent extraction and column chromatography, and the inhibition of these fractions was determined. Spectroscopic analysis of one isolated compound identified it to be keyakinin with the C-glucoside structure of a flavonol. According to the inhibitory indices, the compound was found to be the main cement-hardening inhibitory component of keyaki. Extraction of keyaki with hot water or a blend of keyaki with up to 30% hinoki as a suitable species diminished the cement-hardening inhibition of wood-cement board to a great extent, suggesting that such treatments are economical countermeasures to this inhibition.

Manufacture of wood-cement boards VII: cement-hardening inhibitory compounds of hannoki (Japanese alder,Alnus japonica Steud.)

To identify the cement-hardening inhibitory components of hannoki (Japanese alder,Alnus japonica Steud.), methanol extractives were fractionated by successive organic solvent extraction and column chromatography. Chromatographie analysis and inhibitory indices of the solvent-soluble fractions suggested that glucose and sucrose seem to be the main cement-hardening inhibitory components of Japanese alder. As these compounds are metabolized in vivo even after cutting, the particles after withering are desirable as raw material for wood-cement board.

Bending strength and dimensional stability of tropical wood-cement particleboard

Wood-cement particleboards were produced from Afara ( Terminalia superba) at three cement/wood ratios; 2·3:1, 1·5:1 and 1:1. The nominal densities of the boards were 800, 1000, 1200 and 1400 kg m −3. The modulus of elasticity (MOE) of the boards improved with increase in cement/wood ratio. Both the bending strength (MOR) and board stiffness (MOE) increased linearly with increase in board density. The boards had low values of thickness swelling after 24 h of water immersion. On the basis of bending strength and dimensional stability, the tropical wood-cement boards (produced at 2·3:1 and 1·5:1 cement/wood ratios) are considered suitable for internal construction.

Manufacture of Wood-Cement Boards. III. Cement-Hardening Inhibitory Components of Western Red Cedar Heartwood

Abstract A systematic investigation of cement-hardening inhibitory components from the heartwood of western red cedar (Thuja plicata D. Don) led to the isolation of three lignans. Their inhibitory indices confirmed that plicatic acid has a strong inhibitory effect, and two phenolic lactones, plicatin and dihydroxythuja-plicatin, a weak effect.