Influence of particle size distribution of conventional fine aggregate and construction demolition waste aggregate in Portland cement mortar

Recycled aggregates present a varied mineralogical composition and the grading of these particulates over their particle size distribution influence the aggregate properties as well as those of the composites that they form. This study proposed a comparative investigation of the influence of the particle size distribution of fine aggregates from two different origins, namely, natural crushed stone and construction and demolition waste (CDW). Three particle size distributions were defined, so that each aggregate had its fineness modulus (FM) ranked in the granulometric ranges, following the NBR 7211 Brazilian standard. The following tests were carried out: consistency, bulk density in the fresh state, compression strength, absorption (by immersion and capillarity), dimensional and mass variation. The results showed that the aggregate mineralogical composition impacted the mortar properties and that, when analyzed along with the particle size distribution, CDW showed different and varied behavior as a function of its particle size and distribution. Another finding was that mortars produced with CDW aggregate with granulometry below the lower optimal zone (FM<2.20) presented reduced mechanical and physical performance. Therefore, it was concluded that CDW aggregates should not be included in the same standards as conventional aggregates regarding the fine aggregate granulometric composition.