Estudo da incorporação de lama residual de concreto em pasta de cimento geopolimérico

Abstract

Concrete slurry waste is a material taken from sedimentation tanks that receive water used for washing concrete mixer trucks and yards of concrete dosing plants (CDC). The present study was divided into two main stages: (1) analysis of variance of the chemical composition of the residue from three different CDCs and characterization of the sample with a higher calcium content by different analytical techniques, and (2) incorporation of the residue as a source of calcium in geopolymeric cement pastes and evaluation of properties in the fresh and hardened state. The results of the first phase showed that the material presents significant differences in the chemical composition between CDC, between months of collection and between collection points in the tanks, and the other characteristics are typical of concrete waste. The paste with incorporation, compared to the reference paste, was less fluid; with reduction of initial and final time of hardening; compressive strength 60% higher in 3 days and similar in 28 days; equivalent chemical, mineralogical and thermal composition and characteristic of geopolymeric products. It was concluded that the concrete slurry waste can be used as a source of calcium in a geopolymeric matrix, which gives an acceleration in the solidification of the material and consequent improvement in the mechanical behavior at early ages.