Estudos de parâmetros de dosagem que influenciam as propriedades de concretos permeáveis com agregados reciclados

Abstract

This study aimed to identify dosage parameters that influence mechanical properties and permeability of pervious concretes with and without recycled concrete aggregates. The influence of a 100% natural coarse aggregate (NCA) replacement by recycled concrete coarse aggregate (RCCA) was analyzed; as well as the influence of thickness, cement paste volume, water/cement ratio (w/c) variation and superplasticizer admixture in permeable concretes consistency, mechanical properties and permeability. The theoretical paste thickness (TPT) was determined in order to verify the ability of a cement paste to form a stable film on aggregates surfaces. However, it was not considered as an efficient parameter for dosing pervious concrete. Paste volume for each mixture was also determined. It was found that paste volume was the parameter that best adjusted curves established between mechanical properties and permeability of the studied material. In this research, compressive strength, flexural tensile strength, mass loss through abrasion, permeability coefficient and voids index are among the properties, in the hardened state, which were studied for the production of this type of concrete. Pervious concrete with NCA showed higher compressive strength to that found in RCCA samples, and both types of aggregates reached typical intervals established by ACI 522 (2010). All the concretes that were produced, except the samples with RCCA of 0.25 w/c ratio, reached the tensile strength in the minimum design flexion mentioned in NBR 16416 (ABNT, 2015). Pervious concrete with RCCA showed higher mass loss through abrasion and proved to be more permeable than concretes with NCA. All pervious concretes showed permeability coefficients greater than the lower limit determined in the NBR 16416 standard (ABNT, 2015).