Hydrated cement powders as a low-cost high-performance C-S-H based seeds: Processing parameters inputs

Calcium silicate hydrate (C-S-H) based seeds accelerate Portland cement hydration by shortening the induction period of the chemical reaction. Conventional methods for producing pure C-S-H seeds include the sol-gel process, double decomposition method, and mechanochemical synthesis; however, due to high production costs those are expensive products. This study proposes a cost-effective alternative for C-S-H seeds based in fast hydration of Portland cement as paste exploring the use of low-energy stirring (LES) and wet high-energy milling (HEM). HEM for 30 minutes was sufficient to hydrate majority of anhydrous phases of the cement paste, resulting in the highest C-S-H content. The induction period was reduced by nearly one hour; a comparable performance of commercial pure C-S-H seeds. Additionally, due to coarser particle size distribution of the paste suspension, the hydrated cement seeds achieved dispersion with low content of dispersants and improved the yield stress and the setting time required for consolidation of the Portland cement pastes. Compressive strengths of cement pastes at 12 and 24 hours are comparable to those pure C-S-H seed ones. The findings indicate that the suspension of hydrated cement powder produced via HEM represents a viable and cost-effective method for generating high-performance C-S-H seeds. The seeds prepared in the laboratory through 30 minutes of HEM had a estimate production cost of less than USD 1.00 per kilogram, which is approximately one-tenth the price of commercial seeds. The HEM 30 seeds demonstrated the best performance in cementitious pastes, displaying minor energy consumption to produce 1 MPa of compressive strength. • Alternative seed production method via Portland cement powder hydration in a high-energy milling. • The seeds presented short induction and consolidation periods in cement pastes, and high early strengths, comparable with commercial seeds. • Seeds produced by high-energy milling for 30 minutes reduced the setting time of a Portland cement paste by approximately one-third. • The seeds have a cost estimate of less than US$ 1.00 per kilo, ten times cheaper than the commercial seeds.