Utilization of Supplementary Cementitious Materials in HPC: From rheology to pore structure

The incorporation of Supplementary Cementitious Materials (SCMs) greatly influences the pore structure and rheological properties of High Performance Concrete (HPC). Rheology affects the behaviour of hardened concrete and pore structure can give insight into the microstructure of the concrete and its performance in terms of both strength and durability. Hence, modification of rheology which is possible to control at the time of production can be extremely helpful in enhancing the performance of concrete. In this paper, an attempt has been made to link rheology with pore structure of HPC. The approach will provide better understanding and controlling of HPC and will give impetus to utilize SCMs in the production of HPC. The use of SCMs conserve energy and saves the use of cement which results in reduction of emission of carbon dioxide in the atmosphere. SCMs such as Fly Ash (FA) and Silica Fume (SF) were incorporated as partial cement replacements for the preparation of binary and ternary blended systems. The pore structure of hardened blended systems study was conducted using MIP and rheology such as plastic viscosity and yield stress using the two-point test. It was observed that the incorporation of SF decreased the plastic viscosity of concrete as compared to the reference mix whilst the FA content increased the plastic viscosity and a reasonable relationship exists between plastic viscosity and yield stress. The ternary systems reduced volume of large pores as compared to the reference mix. There exists a reasonable relationship between rheology of fresh concrete and pore structure of hardened concrete.