Al-Kroom Hussein, Elrahman Mohamed Abd, Arif Mohammed A, Mohammed Aya H, Vasquez-Garcia Salomon R, Abdel-Gawwad Hamdy A
Department of Civil Engineering, School of Engineering, The University of Jordan, Amman, 11942, Jordan.
Structural Engineering Department, Mansoura University, Mansoura, Egypt.
Environ Sci Pollut Res Int. 2023 Feb;30(9):24088-24100. doi: 10.1007/s11356-022-23933-6. Epub 2022 Nov 5.
The role of nanozinc source (nanohydrozincite: nHZ; nanozinc oxide: nZO) on the performance of alkali-activated slag (AAS) was explored for the first time in the present work. The results showed that nHZ with different contents (0.5, 1.0, and 1.5 wt%) retards the early hydration rate of AAS, whereas nZO showed the lowest retardation effect. Zn(OH) is the main retarder inside AAS-nZO and AAS-nHZ, which consumes the dissolved Ca (responsible for the early hardening of AAS) from slag to yield calcium zincate hydrate (CZH). The high retardation rate of nHZ is originated from its high affinity to consume much Ca through the formation of additional pirssonite (NaCO.CaCO.2HO) double salt. Although adding nHZ induced the drying shrinkage of AAS, it improved the later compressive strengths (28 to 365 days), especially at low nHZ content (0.5 wt%), via the formation of CASH with lower Ca/Si ratio and higher binding capacity compared to that formed inside AAS and AAS-nZO. A further research is needed to reduce the drying shrinkage and to accelerate the early strength of AAS containing nHZ.
