Hourly three-minute creep testing of an LC3 paste at early ages: Advanced test evaluation and the effects of the pozzolanic reaction on shrinkage, elastic stiffness, and creep

In this study, hourly three-minute creep testing is used to elucidate the evolution of the viscoelastic behavior of cement pastes produced with ordinary Portland cement (OPC), limestone Portland cement (LPC), and limestone calcined clay cement (LC3), from 1 to 7 days after production. An innovative test evaluation protocol, accounting for shrinkage, is used to identify values of the elastic modulus, the creep modulus, and the creep exponent, without making assumptions. The S-shaped shrinkage evolution of the LC3 paste is explained by Portlandite dissolution and the associated redistribution of chemical shrinkage-induced compressive stresses to the remaining solid skeleton. The evolution of the elastic stiffness of the LC3 paste is explained by space filling by C-A-S-H phases. The small creep compliance of the LC3 paste is explained by C-A-S-H which creeps less than C-S-H, and by AFm phases which precipitate in nanoscopic slit pores between C-S-H structures, gluing viscous interfaces.