Durability of desilicated fly ash lime composites

Remediation of residual fly ash from coal fired electric power plants is beneficial to the environment. The chemical, physical, geotechnical and radiological properties of desilicated fly ash (DFA) were investigated. The DFA: lime ratio of 70:30 composite was found to have an average UCS of 8.8 MPa showing 19.5% water absorption after a 24 h soak with a corresponding 23.5% reduction in UCS. The composite was found to meet the minimum UCS requirements after 8 wet and dry cycles but with failure at 10 cycles. The composite was found not to be resistant to acid attack at pH 2 and hence could not be used in the vicinity where landfill leachate may come into contact with the composite. The composite had relative stability against acid rain and normal rain. The composite met the minimum requirement of ASTM C34-13, and thus provide an opportunity for high volume utilization of the residual ash for construction of load bearing walls. (paper)