Inelastic neutron scattering study of the hydration of tricalcium silicate

Inelastic neutron scattering is applied for the first time to monitor directly the concentration of calcium hydroxide formed during the hydration of tricalcium silicate. Results taken between 10 and 40 °C show that the onset of calcium hydroxide formation is delayed at lower temperatures but that the final quantity formed appears to be converging to a temperature-independent value. At 20°C, the 28 day value is 1.3 moles per mole of tricalcium silicate. Combining these results with previous measurements of the free water index made using quasielastic neutron scattering reveals that the hydrogen content of the C–S–H gel decreases significantly at increased curing temperature.