Properties prediction of ultra high performance concrete using blended cement hydration model

• Proposed a hydration model of ultra high performance concrete (UHPC).
• Considered both cement hydration and silica fume reaction.
• Predicted degree hydration of cement, CH contents and mechanical properties.
• Proposed model is valid for both ordinary strength concrete and UHPC.

Ultra high performance concrete (UHPC) consists of cement, silica fume (SF), sand, fibers, water and superplasticizer. Typical water/binder-ratios are 0.15–0.20 with 20–30% of silica fume. The development of properties of hardening UHPC relates with both hydration of cement and pozzolanic reaction of silica fume. In this paper, by considering the production of calcium hydroxide in cement hydration and its consumption in the pozzolanic reaction, a numerical model is proposed to simulate the hydration of UHPC. The degree of hydration of cement and degree of reaction of silica fume are obtained as accompanied results from the proposed hydration model. The properties of hardening UHPC, such as degree of hydration of cement, calcium hydroxide contents, and compressive strength, are predicted from the contribution of cement hydration and pozzolanic reaction. The proposed model is verified through experimental data on concrete with different water-to-binder ratios and silica fume substitution ratios.