Behaviour of Concrete Based on Demolition Aggregates and Dune Sand

Abstract

Faced with the rapid depletion of natural resources and the continuously growing demand for construction materials, the building sector is confronted with a major challenge: how to meet the increasing need for infrastructure while preserving the environment and ensuring the durability of structures? This issue is made even more urgent by rapid urbanisation, driven by technological advancements and population growth, which requires the development of dynamic and adaptable urban fabrics. It is therefore essential to rethink material production methods and prioritise innovative, sustainable solutions to support the sustainable development of cities and infrastructure. Countries around the world rely heavily on concrete for their construction projects, making the depletion of natural resources - the main source of the material that makes up concrete - more intense and therefore more worrisome. Accordingly, the world needs to put more effort into finding alternative resources. Recycling building materials recovered from ‘decommissioned’ buildings and demolished infrastructures or from construction workshops, precast concrete plants and building materials factories - for use as an alternative resource - is a promising idea, showing remarkable eco-friendliness and economic efficiency. In addition, there is an important non-traditional natural source of sand that is still far from being optimally exploited, especially in the field of construction: the desert sand dunes. As a contribution to efforts to find alternative resources for depleting building materials, this work investigates the possibility of combining the recycling of old concrete in the form of coarse aggregates with the utilisation of desert dune sand as an alternative to conventional sand to produce eco-quality concrete. The physical properties of these two alternative materials showed complementarity in terms of workability. A seven per cent improvement in the compressive strength of the concrete was observed compared to control concrete produced from traditionally sourced materials. Some durability indicator tests were carried out to justify the feasibility of twinning these alternative materials as well as the behaviour of the concrete after subjecting it to extreme conditions (abrasion, freeze-thaw, chemical media, high temperature). Overall favourable results are reported.