Optimization of Coarse Aggregate Size Distribution for Preplaced Aggregate Cement Paste Coating Concrete

The novel casting method of preplaced aggregate cement paste coating (PACPC) concrete is helpful in solving engineering problems. The effects of aggregate particle size distribution and W/C on groutability, mechanical properties, and cement efficiency were investigated through experimental and theoretical analysis. The results showed that, with the increase in the proportion of aggregate with finer size, the groutability first decreased and then increased, while the compressive strength and cement efficiency first increased and then decreased. Widening the particle size distribution increased the aggregate packing density by 12.3%, the compressive strength by 12.7%, and the cement efficiency by 30.3% but decreased the groutability by 3.5%. The packing density of the aggregate skeleton was found to be a governing parameter of the performances of PACPC. As the groutability of grouted preplaced aggregate is generally contradictory to the strength, a proper balance should be struck between the fresh and hardened performance.