Estudo de dosagem de concreto permeável para pavimento leve incorporando metacaulinita como substituto parcial do cimento

Abstract

The waterproofing of urban soils directly affects the increase of surface runoff and soil infiltration. The permeable concrete used in pavements presents itself as a mitigating action for these issues. The total absence of fines or the reduction of most of them characterizes the high permeability and low strength of this concrete. In research, metakaolinite is introduced in permeable concrete to partially replace cement. The study was carried out with laboratory tests to check mechanical strength and determine the rate of water infiltration. The mixtures used in this study consisted of two aggregate sizes and two types of coarse aggregates. The tests were performed on reference samples in which there was no replacement of cement. As the work was developed for concrete slabs of permeable, NBR 16416 (ABNT, 2015) determines that the flexural tensile strength reaches the minimum 2 MPa. Thus, it was established that the reference samples should reach a minimum compression strength of 8 MPa. This result was achieved after adjusting the dosages and increasing the sand by 5%. After reaching the goal, 15% of cement was replaced by metakaolinite. The mechanical compression characteristics after the replacement reached a simple compressive strength of approximately 10 MPa and a tensile strength in flexion was approximately 2.1 MPa. The water permeation rate was at values around 0,14cm / s. The study allowed to evaluate that the pebble and the gravel 0 did not present significant differences regarding the mechanical resistance and permeability. The substitution of cement with metakaolinite increased water consumption, which is probably linked to a larger specific area of this material. Metakaolin is a fine material and as one of the characteristics of permeable concrete is the total absence of almost fine materials, its application has not significantly reduced the permeability of concrete.