Cement Conditioning of Waste Materials and Polluted Soil Using the GEODUR Process

In this work, two areas of application of the GEODUR additive in cement stabilization of waste materials have been investigated: stabilization of radioactive contaminated soil and stabilization of municipal solid waste incinerator ash. Preliminary experimental work on a clayey soil contaminated with radioactive cesium and strontium has indicated that the GEODUR process is a technically feasible method for soil solidification. The retarding effects of humic materials in the soil are eliminated by the additive even at low cement contents. The solidified soil is not particularly strong, but has satisfactory water permeability. Retention of cesium is reasonably good, but not as good as for the untreated soil. Retention of strontium is not good but is considerably improved by carbonation. The volume stability during permanent immersion of the solidified products in water is satisfactory, but crack formation during dryout cannot be excluded.

In a parallel experimental investigation of the effect of stabilizing incinerator ash with cement with and without addition of GEODUR it was found that the additive reduces the leachable fractions of copper, zinc, cadmium, and lead. Addition of GEODUR was also found to reduce the rate of release of cadmium, copper, and lead (and possibly zinc) from cement-stabilized incinerator ash in a marine (seawater) environment. Incinerator ash stabilized with 7.4 and 13% sulfate-resistant cement was investigated. It seems likely that application of the GEODUR process in some cases may reduce the amount of cement necessary for stabilization of incinerator ash without sacrificing waste form performance. The results presented are based on a limited number of results from continuing experimental programs which are expected to produce a more complete basis for firmer and more quantitative conclusions.