Mortars produced with recycled aggregates from construction and demolition waste – Analysis and construction site application

Abstract

The valorisation of construction and demolition waste (CDW) as secondary raw material is an important step towards enhancing sustainability in the construction sector, combining environmental benefits with circular economy and sustainable management. The aim of this work is to analyse several mortars produced with different percentages of replacement of natural aggregates (NA) by recycled aggregates (RA) and propose a mix design methodology. First, an extensive literature review was performed and several studies conducted in recent years have been compiled, focusing on RA produced from CDW and incorporated as recycled fine aggregates in mortar matrices. Several properties have been analysed, such as: compressive, flexural and bond strengths, Young’s modulus, capillarity, and shrinkage. Results are discussed, in order to characterize: (i) the binder paste, considering the combination of binders and the respective water-binder and binder-aggregates ratios; and (ii) the different RA and respective proportions (through replacement ratio), quantifying the respective influences on mechanical and durability properties. Subsequently, a methodology is proposed that integrates the aforementioned parameters, thereby enabling the design of mortars with different binders, RA and proportions, tailored to the specific requirements of each application. It has been concluded that, depending on the binder performance (mainly resultant of binder type, combined with its proportion, and the water-binder ratio), RA can have variable influence on the mortar properties. Furthermore, by dividing the mortars under study into groups defined by Feret coefficient intervals according to the binder used and associating the RA with correction coefficients that do not exceed 0.15 per percentage of incorporated RA, it is possible to design the mortar mix according to the desired mechanical properties.