Сlinkerless slag-silica binder: hydration process and hardening kinetics

Building Materials

The article discusses the results of experimental studies comply with modern approaches to the production of high-performance clinkerless binder in order to ensure the possibility of obtaining high-strength composites based on them, hardening under normal temperature and humidity conditions, with-out heat treatment. The binder, belonging to the class slag-alkaline binders, was obtained by grinding all components together in the presence of superplasticizers and a high content of silica fume. The laser granulometry method, XRD – method were used to estimate the particle size, phase composition of the original components and the clinkerless binder. The flocculation and hardening kinetics was evaluated by the penetrometric method and mechanical tests. The data of the phase composition change of the binder, plastic strength, features of mechanical behavior at different stages of hardening are obtained. As a result, the distinctive features of the main periods of heterogeneous processes of structure formation of the resulting binder are revealed. It was found that the high content of microsilica and particles with a diameter of d ~ 1 ÷ 6 μm in the composition of clinkelrss binder, activated during grinding, allowed to increase their hydraulic activity. As a result, the speed of clinkelrss binder setting and hardening under normal temperature and humidity conditions corresponds to the speed of these processes for Portland cement. Setting rate and strength characteristics of clinkerless slag-silica binder meet the requirements for physical and mechanical properties of cement class 32.5 according to EN 197-1: 2000.