ABSTRACT

Red mud from the waste products of aluminum smelting can be classified as pozzolanic, because it hardens and forms a stable and durable compound after mixing with Ca (OH)2 in the presence of water. Incorporating a non-silicate sand fraction, cement mortar with aged gypsum-treated red mud particles resulted in enhanced impact resistance such that values at 20 days and 200 days were found to be in the ratio of 4:1 and 5:1 that of cement mortar without the red mud. Harris found that in the absence of 1–2-mm limestone “aggregates,” no vast increases in strength occurred for any sample up to the age of 20 days. Impact resistance is the ability of a material to withstand a high force or shock applied to it over a short period of time. Though the 1–2 mm limestone “sand” fraction did increase tensile strength of red mud mortar at 20 days, the extent of that influence is uncertain at 200 days.