Mechanical and some durability characteristics of waste marble powder and rice shell ash added foam concrete

An experimental program was performed to evaluate the impact of rice husk ash (RHA) as cement replacement and waste marble powder (WMP) as sand replacement on the microstructural, mechanical and transport properties of foamed concrete exposed to high temperature and freeze-thaw cycles. For this, Ordinary Portland Cement (OPC) was replaced by RHA at 10% and 20%wt of binder and silica sand was replaced by WMP at 25% and 50%wt of fine aggregates to cast foamed concrete mixtures. Two different foam contents of 40 kg/m 3 and 80 kg/m 3 were used in the production of foamed concretes with water/binder (w/b) ratio of 0.70. Two reference mixtures in which silica sand used as fine aggregates and containing no RHA were developed at each foam content. Other foamed mixtures were produced with WMP as fine aggregates and RHA as cement replacement. Fresh properties of mixtures were evaluated by performing yayılma çapı test. Transport properties of foam concretes were investigated, including porosity, water absorption and sorptivity after 90 days curing. Mechanical properties of foam concretes were investigated, including compressive and flexural strength ultrasonic pulse velocity (UPV) after 7, 28 and 90 days. Thermal conductivity and drying shrinkage of concrete specimens were also studied after 90 days. High temperature and freeze-thaw (F-T) durability of foamed concretes were also examined after 200, 400, 600 and 800℃ and 100 and 200 F-T cycles respectively in addition to microstructure investigations. Results show that 10% RHA as cement substitute and 50% WMP as sand substitute give optimum percentage especially at late-age of 90 days at foam content of 40kg/m3. The lowest drying shrinkage and sorptivity were obtained by using 10%RHA and 25%WMP. The results also indicate that water cooled specimens showed more strength loss than air cooled specimens after 200℃. KEYWORDS: foam concrete, waste marble powder, rice husk ash, physico-mechanical properties. May 2021, 103 Page