Shrinkage of concrete with recycled brick aggregates

Abstract

The growing risk of global warming highlights the need for the construction sector to adopt more sustainable practices. Cement production is one of the main contributors to the industry's carbon footprint, prompting extensive research into optimizing mix designs to reduce cement content and improve binder efficiency. Beyond binder optimization, replacing natural aggregates with recycled materials, such as recycled brick aggregates (RBA), offers an additional strategy to mitigate environmental impact by reducing both waste disposal and natural resource extraction. The use of RBA has gained attention for its potential in sustainable concrete production. While its effects on mechanical properties have been studied, its influence on shrinkage remains less understood. This study investigates the impact of partially and fully replacing natural aggregates with RBA on the mechanical properties and, specifically, on autogenous, drying, and total shrinkage of conventional concrete. The results show that RBA replacement up to 25 % does not significantly affect shrinkage, with values comparable to reference concrete. However, higher replacement levels lead to shrinkage increases of up to 50 %. In terms of mechanical performance, a 25 % substitution results in strength reductions of up to 10 %, while higher dosages can lead to losses of up to 40 %. Thus, the partial replacement of natural aggregates with 25 % RBA in C30 concrete presents a technically and environmentally feasible alternative, contributing to the reduction of the concrete's carbon footprint and its overall global warming potential.