Filler to improve concurrent flowability and segregation performance of concrete

Post-blending limestone (LS) filler to replace cement partially in concrete can lower the cost of production and embodied carbon. In order not to jeopardise the compressive strength, the water-to-cementitious materials (W/CM) ratio shall be kept. Because of the reduction in waterto-powder ratio, more superplasticiser (SP) is required to restore workability. Nonetheless, too much SP causes segregation. Hence, it is not clear if post-blending limestone will increase the segregation at similar strength and workability. In this study, various concrete mixes with post-blended limestone are tested for strength, flowability and most importantly, concurrent flowability-segregation performance. It is evident that at the same W/CM ratio, post-blending limestone increases the compressive strength and needs more SP to achieve similar flowability. Nevertheless, at the same water-to-powder ratio, the SP dosage required to maintain similar flowability does not change by too much. More importantly, the overall flowability-segregation performance of concrete containing LS is generally improved. It is because the cohesiveness of concrete improves when part of the cement is replaced by finer limestone. The results suggest that post-blending limestone can increase workability at the same segregation stability or vice versa.