Impact of ZnO on C3S hydration and C-S-H morphology at early ages

The hydration of ZnO doped C3S was investigated. Characteristics of the hydrated pastes including mechanical strength, degree of hydration, microstructure, pore structure, bound water and the chemical composition of C-S H are reported. 0.26 and 0.90 wt% of ZnO in C3S promote the hydration of C3S and the growth of C-S-H needles, resulting in a higher degree of hydration and enhanced compressive strength up to 7 days. Evidence from the XRD quantification and BSE-EDS indicates the change of the chemical composition of the C-S-H from the early age to later ages. BSE-EDS results further revealed the location of the incooperated Zn2+ in the C-S-H structure. Correlation of total heat release, MIP porosity and BET total pore volume to compressive strength/DoH were analyzed. Impact of ZnO amount on the hydration enhancement was also discussed.