COMPRESSIVE STRENGTH AND SULFATE RESISTANCE OF HIGH STRENGTH CONCRETE CONTAINING RECYCLED CONCRETE AGGREGATE AND GROUND BAGASSE ASH

Abstract

This research aims to utilize bagasse ash, a by-product acquired from burning bagasse for an electricity generation in a sugar factory, as a cement replacement in high-strength recycled aggregate concrete. Ground bagasse ash (GBA) was used to partially replace ordinary Portland cement at 20, 35 and 50% by weight of binder. In addition, recycled concrete aggregate (RCA), which was obtained from crushing demolished concrete columns, was used as a fully substitute for natural coarse aggregate in the concrete. The compressive strengths of concrete at 7, 28 and 90 days were investigated. In addition, the durability of concretes in terms of expansion and weight loss due to 10% magnesium sulfate solution attack was also evaluated. The results indicated that the replacing of crushed limestone with RCA had a slightly reduction on the compressive strength of concrete as compared to conventional concrete (CT concrete). However, the use of GBA as 20% by weight of binder to replace OPC could promote the compressive strength of the concrete to be higher than CT concrete at the age of 90 days. In addition, all concretes exhibited compressive strengths higher than 550 ksc suggesting that they are high strength concrete as specified by ACI 363. Considering the magnesium sulfate resistance of concrete, RCA had a clear negative influence on durability of concrete. The expansion of recycled aggregate concrete could be improved by utilization of GBA for up to 50% of cement replacement, which was better than the CT concrete. However, the surface damages of the recycled aggregate concrete due to magnesium sulfate attack occurred when the volume of GBA was 50% by weight of binder that resulted in increasing the weight loss of concrete.