Application of Nanomechanical Methods in Investigation of C–S–H Gel/Cement Grain Interface

Investigation on the mechanical properties of cement-based materials at micron and submicron scales is important for understanding the overall performance, particularly of high-performance concrete (HPC). Due to low water-tocement ratio of HPC, a large amount of unhydrated cement grains remain in matrix, and a significant impact of the interface between C–S–H gel and cement grains on concrete behavior could be expected. Recent progress in experimental nanomechanics opens new access to nanoengineering of cement-based composites. In this paper, nanoindentation and viscoelastic modulus mapping were used to study the interfacial properties. The interface width measured by modulus mapping was around 200 nm as compared to a rough estimation of less than 5 μm by nanoindentation, due to the fact that two orders of magnitude increase in spatial resolution could be achieved with modulus mapping