Combined use of waste concrete and glass as a replacement for mortar raw materials

The construction industry offers one of the most attractive options in the use of recycled materials due to its large consumption of raw materials and high construction work rates. Also, the debris from construction and demolition is responsible for a high participation rate in the generation of waste, with concrete being a major contributor in this category. Waste glass powder, on the other hand, is a material that offers an excellent alternative to replace cement due to its well-known pozzolanic properties. Hence, the combined behaviour of fine recycled concrete aggregates and glass powder of different particle sizes in mortars has been studied. Different mixtures are analyzed with the aim of minimizing losses in mechanical properties and durability in an attempt to maximize the amount of replaced materials. Due to the delayed pozzolanic reaction by the glass powder, the samples present highly satisfactory results at 90 days of curing, with values of their properties close to those of the control mortar. The results are encouraging when glass powder with a smaller particle size is used due to its filler effect combined with its pozzolanic activity, making it possible to replace up to 20% of glass powder with a maximum size of 38 µm, with up to 30% of fine recycled concrete aggregates. Finally, the evaluation of greenhouse gases showed that the simultaneous incorporation of both types of waste reduces the CO₂ emissions associated with concrete by up to 19%.