Impact of C-S-H seeding on hydration and strength of slag blended cement

The impact of C-S-H seeding on the hydration of slag blended cement was systematically investigated, trying to understand and explore the potential of C-S-H seeding in blended cement. Three levels of substitution of cement by slag were investigated: 50, 75 and 95 wt%. Compressive strength, calorimetry, in-situ and fresh disc XRD experiments were carried out. Results show that C-S-H seeding improves the performance of slag blended cement significantly with regards to strength at early and later stage. Quantitative XRD analyses show how C-S-H seeding influences the clinker hydration kinetics. The microstructure of hardened blended cement paste was investigated using electron microscopy and mercury intrusion porosimetry. The results show that C-S-H seeding altered the microstructure dramatically by refining the porosity. Correlation of strength to heat release and pore structure indicates that there is structural impact of C-S-H seeding besides the impact on kinetics in the hardened samples.