Acceleration of Portland cement with lithium, sodium and potassium silicates and hydroxides

These systematic investigations focus on the effect of lithium, sodium and potassium silicates (water glasses) and their hydroxides on the hydration of ordinary Portland cement. All tests were performed with CEM I 52.5 R and the different alkaline species. Besides the well examined sodium and potassium silicates, lithium water glasses and hydroxides were admixed. Their effects on setting time, strength, heat of hydration and phase formation of cementitious systems were compared to each other and related to the different silicate modules of the used silicates. Due to the systematic approach the investigations exhibit a new view of the reactivity of lithium, sodium and potassium in Portland cement hydration. The setting of limes was monitored by time of ultrasonic transmission. Accelerating effects of the different silicates are related to the alkaline species with comparable silicate content. The acceleration effect in the first two days could be observed trough the C3S and C-S-H content during hydration compared to the unmodified Portland cement. Resulting strength of the admixed systems are measured based on EN 196-1.