Effect of some Physical and Chemical Treatments on the Mechanical and Physical Properties of Acacia nilotica Wood-Cement Mixture

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Tarig Tag El Sir Hassan, Musa
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The study investigated the effect of some technological factors on the properties of Acacia nilotica (sunt) wood-cement mixture in two separate experiments. Wood slabs were obtained from 30 sunt trees in Abu kuk Forest. Commercial cement was used. The first experiment was factorial to study the duration effect of cold water extraction (0, 7 and 14 days) in addition to six levels of commercial calcium chloride (1, 1.5, 2, 2.5, 3 and 3.5 %, based on cement weight) on the properties of the wood-cement mixture. In total, 72 specimen blocks (5*10*60Cm3) were prepared using metal molds. After 24 hours, the blocks were removed from the molds and were then moistened with water for 28 days. The wood-cement mixtures were tested for mechanical (modules of rupture, compressive strength and hardness) and physical (water absorption, density, dimension swelling and volumetric swelling) properties. Analysis of variance and Duncan Multiple Range test were performed to study the significance of the treatments and their interaction. Although the effect of extraction duration on the mechanical properties and water absorption was dependent on the level of calcium chloride, extracted wood had significantly higher strength and density and lower water absorption than non-extracted wood; there is no need for more than" 7-days extraction. No significant differences in density, 2 hours water absorption and swelling were found between the six levels of calcium chloride when using non-extracted wood (control), increasing the level of calcium chloride in the mixture was associated with a decrease in strength properties and an increase in water absorption. When the wood was extracted, increasing the level of calcium chloride was associated with an increasing trend in the strength properties and a decrease 2-hours water absorption; the level at which the strength properties start to increase varied among properties and extraction levels. The second experiment was conducted to study the effect of the pressure levels (0.05, 0.07 and 0.10 kg/cm and cement replacement by commercial lime (0, 10, 20, 30 and 40%) on wood-cement mixtures. The wood was extracted for 7 days and calcium chloride was added at 2% based Each combination of the above treatment was replicated four times giving a total of 60 specimen blocks. The specimens were manufactured and the properties were determined as in the first experiment. Increasing the pressure from low to medium level, was resulted in increasing the compressive strength -when replacing 10, 20 and 30% lime and green density; while the increasing from medium to high level increased the hardness and basic density. More concentration of lime in the mixture resulted in a significant decrease in strength properties and density, but increased the water absorption. Replacing up to 30% lime with increasing the pressure from low level did not statistically affect the compressive strength. In all pressure levels, MOR has compliance the British Standard (1.27 N/mm2) requirements.
Effect of some Physical and Chemical Treatments on the Mechanical and Physical Properties of Acacia nilotica Wood-Cement Mixture