EVALUATION OF SULFATE EXPANSION IN SOIL-CEMENTS

This paper presents the results of an evaluation of internal sulfate a ttack in soil-cements. Differences in rates and amounts of expansion w ere evaluated for several aggregate types. Sulfate expansion of soil-c ement was evaluated using a modified version of ASTM Test Method for L ength Change of Hardened Hydraulic Cement Mortar and Concrete (C 157) that utilized a falling weight compaction procedure and large 76 by 76 by 286-mm bars. This paper compares this new test procedure with alre ady established means of evaluating internal sulfate expansion of soil -cement. Expansion of small 25 by 25 by 286-mm bars compacted with a h and tamper was compared to expansion of the large bars compacted by a falling weight. Some small bars were cured in lime-saturated water, wh ile others were cured in humid air. Much better results were achieved when curing took place in water. The new large bar method simulated fi eld expansions better than the small bars. The use of small bars cured in lime-saturated water is recommended only when results are needed q uickly. Large bars cured in water are recommended whenever time permit s.