Insight into Early-Age Performance of Cement Paste/Mortar with C-S-Hs-PCE and Aluminum Sulfate

This work aimed to perform the insight into the performance at early age of cement paste/mortar with calcium silicate hydrate seeds-polycarboxylate (C-S-Hs-PCE) and aluminum sulphate. The performance was evaluated using the setting behavior and compressive strength. Hydration heat liberation, chemical shrinkage, X-ray diffraction, and differential thermal analysis were performed to explore the related mechanism. The results indicate that C-S-Hs-PCE can reduce the setting times of paste and increase the compressive strength of mortar with aluminum sulfate at 6 and 12 h and 1 and 28 days. These results are mainly related to the acceleration hydration of tricalcium silicate and facilitation of ettringite and calcium hydroxide formation. Aluminum sulfate and C-S-Hs-PCE promote the cement hydration in two manners: (1) they significantly enhance the heat flow and end the acceleration period earlier; and (2) aluminum sulfate prolongs the induction period, whereas C-S-Hs-PCE shortens it. These findings provide theoretical guidance for the development of a new alkali-free accelerator as well as the application of C-S-Hs-PCE.

Automated summary

This study investigated the impact of C-S-Hs-PCE and aluminum sulfate on the early-age performance of cement paste/mortar, finding that C-S-Hs-PCE can shorten setting times and increase compressive strength. Aluminum sulfate and C-S-Hs-PCE promote cement hydration by accelerating heat flow and end the acceleration period earlier, as well as prolonging or shortening the induction period, respectively. These findings offer theoretical guidance for the development of new alkali-free accelerators and the application of C-S-Hs-PCE.