Understanding the effect of hydrozincite and witherite nanominerals on the performance and phase composition of alkali-activated slag

The individual effect of nano hydrozincite and witherite (nHZ and nW, respectively) with different contents (0, 0.5, 1.0, and 1.5% by weight of slag) on the performance of alkali-activated slag (AAS) at early (from 1 to 7-days) and later ages (from 28 to 365-days) of curing was evaluated. The results proved that incorporating nHZ caused a retardation impact on the early hydration rate of AAS; whereas nW demonstrated an acceleration effect. These opposite effects were ascribed to the formation of zinc and barium hydroxides through the alkali-dissolution of nHZ and nW at 1-day of curing. A remarkable change in Ca/Si ratio within calcium silicate hydrate has been identified at both AAS-nHZ and AAS-nW mixtures. The proposed approach succeeded in the production of the hardened materials with high mechanical performance (55-64 MPa) using low nanominerals (0.5 wt%) and NaOH (3 wt%) contents.

Automated summary

The individual effects of nano hydrozincite and witherite on the performance of alkali-activated slag (AAS) were evaluated. It was found that nano hydrozincite caused a retardation effect on the early hydration rate of AAS, while witherite demonstrated an acceleration effect. These effects were due to the formation of zinc and barium hydroxides through alkali-dissolution. Changes in the Ca/Si ratio within calcium silicate hydrate were observed in both AAS-nHZ and AAS-nW mixtures. The proposed approach successfully produced hardened materials with high mechanical performance using low nanomineral and NaOH contents.