Immobilization of active concrete debris using soluble sodium silicates

Demolition of biological shields will generate large quantities of active concrete debris. Sodium silicate solutions have already been shown capable of immobilizing such debris in a pellet form; this new study investigates debris immobilization via a silicate solution/debris slurry. A study of the physical and chemical properties of demolition debris has been undertaken. Laboratory scale trials have shown that only the finer (''less than''5mm) debris fractions set satisfactorily when mixed with a sodium silicate solution. Debris from ordinary portland cement concrete set more quickly than that containing a 30% pulverized fuel ash cement replacement. The particle size of the debris is a major factor in the setting process, but chemical interactions are also significant. A ratio of 1.2:1 debris:sodium silicate solution (SiO2/Na2O = 3.30), produced an optimum mix. A brief study of the logistics of a full scale process plant has also been made. (author)