Effect of Synthetic Aggregate Thermal Transformation on Performance of Concrete

The investigation involved twelve different synthetic aggregates produced in the TTl rotary kiln, one commercially produced synthetic lightweight aggregate, and one regular weight aggregate. Each aggregate was used in concrete which was subjected to a variety of physical durability investigations including autoclave expansion, long-time reactivity, freeze-thaw, and shrinkage. From the results of the study it was found that (a) incompletely burned synthetic aggregates resulted in poor performance in the standard ASTM C-290 freeze-thaw test for concrete, (b) potentially destructive autoclave expansion occurred in some concretes, (c) long-time reactivity curing produced no significant volume changes following initial autoclave treatment, and (d) shrinkage studies showed no relationship to degree of transformation of the synthetic aggregates,.