Early-age deformation and autogenous cracking risk of slag–limestone filler-cement blended binders

This article presents an experimental comparative study of the early-age behavior of binary and ternary cementitious matrices, combining Portland cement (PC), ground granulated blast furnace slag (BFS) and limestone filler (LF). The objective of this work was to quantify the influence of the composition of various blended binders on their physico-chemical evolution and early-age autogenous cracking risk. For this purpose, measurements of the rate of reactions, chemical shrinkage, autogenous shrinkage in free and restrained conditions and mechanical performances were performed on 12 binders prepared with the same water-to-cementitious materials ratio (w/cm = 0.32) and various dosages of PC, BFS and LF. The result analysis showed that the dilution effect reduced the early-age chemical shrinkage while the filler effect and the slag reactions tended to accelerate its development after a few hours of hydration. The substitution of PC with BFS and LF also led to both refining the 28-days pore size distribution measured by mercury intrusion and increasing the magnitude of early-age free autogenous shrinkage. However, in spite of their higher autogenous shrinkage potential, the binary and ternary binders very often exhibited later autogenous cracking ages than the control Portland cement paste.