Effect of Some Treatments and Cement/Wood Ratio on the Quality of Mesquite (Prosopis Chilensis) Woodcement Aggregates

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Ali, Hamdon
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Portland cement is an inorganic binder that can be used for the production of composite panels. Many studies have focused on understanding the complex behavior of wood-cement water mixture. Wood-cement panels are commanding renewed interest because of their potential application in building etc; they have specific advantages over conventional resin bonded particleboard which include resistance to outdoor exposures, fire, insects and rots. This work was designed to study the compatibility of mesquite (Prosopis chilensis) wood with ordinary Portland cement for production of wood-cement aggregates. The wood materials used for this experiment was derived from Prosopis chilensis (mesquite) collected from Bara area, Northern Kordofan state. The experimental part of this study consisted of four main experiments; the promising results obtained in the former experiments will be used in the latter one. All experiments were conducted using Completely Randomized Design (CRD) with three-five replicates. The first experiment was designed to study the extractive content of mesquite wood (solubility) using cold, hot water and mild alkali extraction methods. The alkali used was Sodium hydroxide with two concentrations (0.5 and 1) %. There were significant differences between the extraction methods. The greatest amounts of extractives were obtained when using 1% NaOH followed by 0.5% NaOH. The second experiment was designed to determine the suitable treatment/s to be applied for mesquite wood to improve it’s compatibility with ordinary Portland cement. The treatments used were: soaking in cold water for 14 days; soaking in Sodium hydroxide solution (0.1% ) for 24 hours, addition of calcium chloride as 3% based on cement weight and addition of gypsum as ix 20% based on cement weight. Untreated wood was used as control to compare the effect of above mentioned treatments. The results showed that the best treatment was the addition of gypsum followed by calcium chloride and control as indicated by the compressive strength of the aggregates. This indicates that mesquite wood can combine well with cement without treatments. The Third experiment was designed to study the effect of cement- wood ratio namely 2:1; 3:1; 4:1 and 5:1. As the ratio increased all the studied variables (density, compressive strength, and water absorption) were improved, and the aggregates produced with cement wood ratio of 3:1 were found to have reasonable weight, good strength and reliable density. This implies that 3:1 cement wood ratio is the suitable and recommended ratio to be used for untreated mesquite wood. The fourth experiment was designed to study the effect of cement replacement by gypsum as 10, 20, 30 and 50 percent based on cement weight using the recommended cement-wood ratio (3:1) that obtained in the third experiment results. Generally lower replacement percentages (10, 20%) were found to improve the compressive strength and water absorption, while increasing the replacement percentages more than 20% caused reduction in the density of the aggregates which negatively affect the compressive strength of the aggregates