Thixotropy of self-compacting concrete containing recycled aggregates Available to Purchase

The effect of recycled-concrete aggregate replacement level and binder composition on the thixotropy of two grades of self-compacting concrete (SCC) was investigated with a coaxial rheometer using the stress-growth test. Across the two SCC grades, the binder composition was changed while keeping the aggregate and paste volumes constant. Within a grade, the coarse aggregate composition was varied and the degree of thixotropy was found to increase with an increase in recycled aggregate replacement level (by volume) to 50% and 100%. This was attributed to the higher internal friction associated with the recycled aggregates. Enhanced thixotropy was noted in the mixes containing supplementary cementitious materials, with metakaolin being more effective than silica fume in this regard. Measurements of the drop in apparent viscosity yielded predictions for the degree of thixotropy that were comparable to those obtained from the breakdown area associated with a typical stress-growth test.