Structural build-up, hydration and strength development of cement-based materials with accelerators.

• The hydration, structural build-up and strength development of cement pates with different accelerators were investigated. • Accelerators increase the structural build-up rate by different mechanisms. • Mechanical efficiency of C-S-H may give wrong ranking on the efficiency of C-S-H. Fast structural build-up and strength development of fresh/hardened cement-based materials are always desired in many scenarios, where accelerators are often used. In this paper, the hydration, structural build-up and strength development of cement pates with different accelerators were investigated. The growth of static yield stress was used to characterize the structural build-up of fresh cement paste with 1% nano silica. Calorimetric curves, zeta potential and conductivity of pastes and strength development of mortars were also measured. Results showed that accelerators promote the reaction of C 3 S or C 3 A at different stages and in different mechanisms. Mechanical efficiency of C-S-H determined by growth of elastic modulus or yield stress over cumulated hydration heat may give wrong ranking on the efficiency of C-S-H. Apart from formation of C-S-H gel, structural build-up may originate from other sources. [ABSTRACT FROM AUTHOR]