Mechanical and hydration properties of low clinker cement containing high volume superfine blast furnace slag and nano silica

•Low clinker cement with 70% superfine blast furnace slag shows superior strength.•Superfine blast furnace slag decreases the hydration heat of low clinker cement.•Superfine blast furnace slag modifies the pore structure of low clinker cement paste.•Nano silica improves the mechanical and hydration properties of low clinker cement. Substituting part of cement clinker with superfine blast furnace slag (SFBFS) is a wonderful way to solve the problems of environmental pollution and resource consumption caused by cement manufacture. In this study, a low clinker cement containing high volume SFBFS was prepared with nano silica (NS) for property improving. The low clinker cement containing no more than 70% SFBFS exhibited higher mechanical strength than plain cement. At 90 d, the compressive and flexural strength of low clinker cement containing 70% SFBFS were 9.8% and 27.3% higher than that of plain cement. The hydration exothermic action of low clinker cement were significantly decreased, in comparison to plain cement. The results of X-ray powder diffraction and thermogravimetric analysis revealed that SFBFS was involved in the pozzolanic reaction, resulting in the consumption of CH and the production of C-S-H. The result of mercury intrusion porosimetry demonstrated that the incorporation of SFBFS refined the pore structure of blended cement pastes. In addition, NS played an important role in improving the mechanical strength, promoting the hydration and modifying the pore structure of low clinker cement blended with SFBFS.