Properties of cement-free concrete cast by finely grained nanoslag with the NaOH-based alkali activator

This study concerns properties of nanoslag (NS) concrete cast with the alkali activator to enhance the hydraulic activity. The NS was produced by the cyclone segregation method to meet the fineness of 15,000 cm2/g. Properties of fresh NS concrete was evaluated by a rise of the adiabatic temperature and the setting time. Simultaneously, a development of the strength and the chloride diffusivity for NS concrete was assessed. As a result, hardening of NS concrete was about 1 h fastened, due to an enhanced activity between NS and mixing water, which was ensured by a sharp increase in the adiabatic temperature at a very early age, compared to OPC concrete. NS concrete had a lower rate of chloride transport, when exposed to a salt solution, presumably due to a refinement of the pore structure: a significant decrease in the volume of the capillary pores was observed, which otherwise would indicate an equivalent level of chloride transport. From a survey on the environmental impact, it was clearly seen that the use of NS concrete would dramatically reduce the emission of CO2 gas in the process of concrete materials, ranging about 70% reduction to Portland cement concrete.