ASR Behavior of Class C Fly Ash Modified Cement

摘要

The class C fly ash, produced by power plants burning sub-bituminous coal, has self-cementing properties. As such, this fly ash could be potentially used as a cement replacement agent. In the work to be presented, we have addressed two concerns associated with class C fly ash modified portland cement, mamely, (i) the strength behavior, and (ii) the alkali-silica reaction potential. Two methods were utilized to study the potential effects of alkali-aggregate reactions: (1) a relatively quick autoclave expansion test method, and (2) a long term beam expansion test developed by the Kansas Department of Transportation. The mortar bars for the autoclave expansion test were made in accordance with ASTM C 227. Aggregates for these expansion tests were obtained from various sources in Kansas. Standard sand was used to obtain bench mark results. The fly ash was obtained from Kansas City Power and Light plant burning sub-bituminous coal from Wyoming. Tests were performed using blends of varying ash content, aggregate-cementitious material ratios and water-cementitious material ratios. A large number of bars were tested to obtain statistically meaningful results. Strength tests were performed using 50 centimeters cubes for these blends.