Investigation on Effect of Additives on Thermal Conductivity of Herbaceous Fiber Reinforced Cement Composite

In this research، fiber reinforcement cement composites (A and B) with low thermal conductivity were produced. Composites type B were produced by two levels of fibers (Equisetum telmateia)، 15 and 25%، three levels of silica fume gel، 0، 7 and 10% and three levels of fly ash، 0، 20 and 30%. In composites type A fly ash was replaced by aluminium powder in three levels، 0، 0. 08 and 0. 1% (all percentage by weight) to manufacture composites with target density and thickness of 1. 10 g/cm3 and 13 mm respectively. Results of tests to determine effects of additives on thermal conductivity of mentioned composites have shown that the increasing amount of each of the mentioned additives would significantly affect thermal conductivity of the experimental composites. Least thermal conductivity coefficient was observed 0. 14 W/mK in composites type A، consisting 25% fiber، 10% silica fume gel and 0. 1% aluminium powder. In composites type A with increasing the aluminium powder to 0. 1%، silica fume gel to 10% and fiber to 25%، the thermal conductivity reduced 36، 34. 78 and 42. 86 % respectively. Least thermal conductivity coefficient was measured 0. 17 W/mK in type B composites containing 25% fiber، 10% silica fume gel and 30% fly ash. In composites type B with increasing the amount of fly ash to 30%، silica fume gel to 10% and fiber to 25%، the thermal conductivity did decease in order of 39. 18، 37. 5 and 47. 62%.