Influence of recycled aggregate replacement and fly ash content in performance of pervious concrete mixtures

The construction industry is responsible for large volumes of raw material extraction for cement manufacturing, and also disposes of construction and demolition wastes (CDW) in landfills. The pervious concrete is considered a sustainable alternative for pavement, since its main characteristic is to permeate the water, allowing its reuse. In this sense, for an adequate use it is necessary to optimize its properties in its dimensioning and maintenance to avoid the clogging of its voids. In this way, the main purpose of this research was to analyze the use of recycled aggregates (RA) from construction and demolition waste and fly ash in pervious concrete. Thus, two series of pervious concretes, one with a w/b ratio of 0.25, 0.30, and other keeping w/b ratio constant (0.30) and 10% of cement replacement by fly ash were investigated, all with replacement of natural by recycled aggregate (25, 50, 75 and 100%). Clogging, surface abrasion test, compressive and flexural strength, permeability coefficient, infiltration rate, scanning electron microscopy (SEM) and x-ray microtomography were performed. The results showed that the incorporation of 10% fly ash in pervious concrete with 75% of recycled aggregate content showed an increase of 6% tendency to clogging compared to the reference pervious concrete. In addition, the higher levels of recycled aggregate showed a greater tendency to clogging in samples, where the highest tendency was found in the 50% replacement concrete, while the reference concrete was 46% less susceptible to clogging. It was verified that the increase of the recycled aggregate content in pervious concrete provided the increase of surface abrasion. The microstructural investigation showed a good relationship between the macrostructural properties and the void content in pervious concretes. (C) 2020 Elsevier Ltd. All rights reserved.