Influence of particle packing on the properties of multi-component cementitious systems

The use of multicomponent binder which consists of ordinary Portland cement (OPC) combined with one or more supplementary cementitious materials (SCMs) has become ubiquitous enhancing sustainability and improving the packing density of the cementitious systems. The particle arrangement within cementitious materials is crucial for the performance of the paste, which represents the most variable aspect of mortar/concrete. The experimental study applies two established methods, the wet packing method (WPM) to optimize binder compositions and the modified Toufar model (MTM) to proportion fine aggregates, reducing void content in ternary-component cementitious systems. WPM determines the wet packing density (WPD) and optimizes the composition of various ternary-component systems consisting of cement (C) and SCMs such as flyash (F), ground granulated blast-furnace slag (G), metakaolin (M), and silica fume (S). The maximum WPD is achieved for the combinations of C50F20G30 (0.746), C50F35M15 (0.752), C60F30S10 (0.758), C50F35M15 (0.746), C60G30S10 (0.762), and C75M15S10 (0.738). The MTM method achieved the highest packing density (0.71) with the lowest void ratio (0.407) when compared to the JDD, IS 383:2016, and IS 650:2008 methods. This optimized packing led to enhanced mechanical properties, pozzolanic reactivity, reduced capillary sorptivity, and drying shrinkage with ternary mortar mixes of C-F-G, C-F-M, C-F-S, C-G-M, C-G-S, and C-M-S attaining maximum compressive and flexural strengths at 90 days. The packing density and pozzolanic reaction are the primary cause of this enhancement in mortar mixtures.