Understanding the role of C–S–H seed/PCE nanocomposites, triethanolamine, sodium nitrate and PCE on hydration and performance at early age

Compared to thermal curing, the application of C–S–H/PCE nanocomposites (CPNs) and triethanolamine (TEOA) compound admixture is a green and highly efficient hydration acceleration strategy. Commercial CPNs usually contain polycarboxylate (PCE) and residual sodium nitrate (NN). It is still uncertain whether their presence has some influence on the hydration of cement with this admixture. The experimental results show that TEOA-NN promotes hydration, and then the setting times are shortened and the early compressive strength is increased; it advances the start of the acceleration period, slightly increases tricalcium silicate (C3S) hydration, or further improves tricalcium aluminate (C3A) hydration. TEOA-PCE significantly retards C3S and C3A hydration at 1 d. In contrast, TEOA-CPNs exhibit excellent mechanical properties and hydration heat owing to its strong promotion of the hydration of C3S and C3A. These results can provide guidance for the formulated design of CPNs-based admixtures.