Optimization of alkali-activated binder reactive powder concrete based on concept of packing density

Abstract

Reactive powder concrete (RPC) stands as an ultra-high-performance concrete (UHPC), widely acknowledged for its exceptional strength and durability. However, the high carbon footprint of RPC is a concern due to its substantial reliance on Portland cement. The development of alkali-activated binder reactive powder concrete (AAB-RPC) offers a potential alternative, seeking not only to enhance durability but also to promote sustainability. Despite this, a comprehensive solution to the optimized design of AAB-RPC is currently unavailable. While the packing density method, a physics-based mix design approach, has been proven effective in Portland cement-based RPC, its applicability and extensibility to AAB-RPC system remain unexplored. This study aims to optimize the strength design of AAB-RPC by using the packing density method. It employs modified continuous packing particle models to design various AAB-RPC mixtures, utilizing distribution modulus q and liquid-to-solid volume ratio as design variables. The selection of optimal mix proportions is based on packing density and workability, followed by the analysis of compressive strength at different ages. The results show that the maximum strength of AAB-RPC occurs when q value ranges from 0.25 to 0.30. Furthermore, a positive correlation is observed between wet packing density and compressive strength. Additionally, a strength formula for AAB-RPC, grounded in q value, maximum packing density, and age, achieved an impressive coefficient of determination (R2) of 0.938. The results demonstrate the efficacy and reliability of the wet packing density method in AAB-RPC mixture design.