Mechanical and thermal properties of aluminate cement paste with blast furnace slag at high temperatures

The effect of blast furnace slag (BFS) on the mechanical and thermal properties of calcium aluminate cement (CAC) subjected to high temperature was evaluated in this study. The hydrate phase, micromorphology, and porous structure characteristics were determined by differential thermal analysis/thermogravimetry, X-ray diffraction (XRD), scanning electron microscopy, and nitrogen adsorption -desorption. The thermal conductivity of the pastes was evaluated using a thermal conductivity analyzer. The results indicated that with an increase in BFS, the thermal conductivity of CAC-BFS blend samples increases initially and decreases subsequently, and the compressive strength of the CAC-BFS blend samples exhibits the same trend. The addition of 30-40% BFS positively influenced the pore size distribution of cement paste and improved the thermal conductivity (lambda) of the CAC-based composites subjected to high temperature, enhancing the mechanical properties of the CAC-based composites. Thermal conductivity also decreases at increased temperatures and correlates with pore structure. The experimental results indicate that the amount of BFS added considerably affects thermal conductivity and compressive strength, and that the optimal amount of BFS can be determined. (C) 2019 Elsevier Ltd. All rights reserved.