The effect of granulometry of natural and recycled coarse aggregate on permeable concrete properties

Abstract

The development and improvement of permeable concrete stands out as a sustainable alternative for urban rainwater management, which, thanks to its structure with interconnected pores, has the capacity to capture and transport water. The low proportion or absence of fine aggregates provides the porous structure of permeable concrete and allows greater permeability, but may affect some of its mechanical characteristics, both in the fresh and hardened states, such as workability, compressive strength, tensile strength, permeability coefficient, among others. To make this solution even more sustainable, it is also possible to replace natural coarse aggregates by recycled ones, minimizing the inadequate final destination of civil construction waste. Therefore, it is necessary to evaluate the influence on the properties of pervious concretes when substituting natural aggregates by recycled ones. The objective of this study was to develop different mixtures of pervious concretes, by varying the granulometry of the natural and recycled coarse aggregates from construction waste, and to evaluate the mechanical properties of concretes in the fresh and hardened states, through tests to determine consistency, compressive strength, tensile strength, and permeability. It was possible to conclude that the use of recycled aggregate contributed to increase the permeability coefficient of permeable concretes, being this effect more evident for the mixtures with larger recycled coarse aggregate. All concrete compositions studied presented a permeability coefficient above the minimum limit stipulated for pervious concrete, 0.001 m/s. All mixtures of permeable concrete with recycled aggregate presented compressive strength values above 20 MPa, in compliance with regulatory requirements. The mixture using recycled aggregate with better performance presented 60% higher compressive strength (average 31,10 MPa) when compared to other mixtures, and 34% higher compared to a mixture of the same granulometry using natural aggregate. This mixture also presented permeability of 0,49 cm/s; Splitting tensile strength 3,30 MPa; Flexural strength 2,88 MPa.