Resistance to magnesium sulfate and sodium sulfate attack of mortars containing wheat straw ash

Abstract

Magnesium and sodium sulfate resistance of mortars containing wheat straw ash (WSA) was investigated. WSA was obtained by burning of wheat straws in electrical furnace under controlled conditions. When this ash is rapidly cooled, a good pozzolanic material is obtained. In this study, resistance to magnesium sulfate and sodium sulfate attack of mortars containing different levels of WSA was investigated. Compressive and flexural strength, density and mass changes of mortar specimens in water and sulfate solutions were determined for 180 days. The strengths of mortars generally increased in magnesium sulfate solutions during the tests. However, decreasing strengths, after 56 days in solution at a concentration of 40,000 mg/l at the 24% replacement level, can be accepted as an indication of a negative development trend for later days. WSA replacement affected beneficially compressive strength of mortars in sodium sulfate solutions. When flexural strength results are considered, performance or Portland cement (PC)-WSA mortars are not satisfactory.