Stabilization of Geothermal Residues by Encapsulation in Portland Cement-Based Composites

Abstract

Presented are the results from a laboratory test programs conducted to identify and evaluated materials for converting hazardous geothermal residues to a non hazardous and potentially usable form. The results indicate that the residues can be effectively incorporated, as a fine aggregate, into Portland cement based composites. Five geothermal residues obtained from sites in the Salton Sea area of California were evaluated. Based upon the results from waste extraction tests, three of these were classified as hazardous. After mixing with cement, the leach rates were all well below specified levels. Although a structural grade composites were produced gradual reduction in properties with time up to 1 year were noted. This indicates ongoing chemical reaction between the cement paste and the constituents of the residues. Further research is necessary before the composites could be considered for use instructural applications.