Micromechanical testing and modelling of blast furnace slag cement pastes

This work aims to understand deformation and fracture processes in blast furnace slag cement pastes made using CEM III/B which is commonly used in the Dutch infrastructure sector. First, based on our previous work on Portland cement pastes, a micromechanical model utilizing nanoindentation and X-ray computed tomography (CT) for input is created. Statistical analysis are carried out and shows that grayscale values from X-ray CT scans of slag pastes can be linearly correlated with nanoindentation measurements of elastic modulus. Simulations of uniaxial tension are then performed for varying w/c ratios using the Delft lattice model and microstructure obtained from X-ray CT. In addition, advanced micromechanical experiments for estimating the micro-scale tensile strength and elastic modulus are performed. Experimental and simulation results are then critically discussed and compared. It shows that simulation results match the measured tensile strength quite well although some discrepancy does exist at lower w/c ratios. In addition, the observations are compared to our previous findings on ordinary Portland cement pastes. It is found that tensile strength and elastic moduli of slag pastes at 28 days are higher than those of Portland cement pastes with the same w/c ratio. This study will form a basis for micromechanical testing and modelling of blended cement paste systems in the future.