Avaliação da aplicação de cinzas de termelétrica em blocos intertravados de pavimentos

Abstract

Due to the significant generation of ashes from a thermoelectric plant and the increasing cost of storage of these wastes, it was decided to verify, through the research, the incorporation of bottom ashes into concrete used in interlocking blocks for paving. Firstly, after the conventional and alternative materials were collected, environmental tests (leached and solubilized extract) and physical characterization tests (grain size analysis, real density, liquidity and plasticity limits and hygroscopic moisture) were performed. Through the grain size curves of each material, it was observed that ashes could replace, by mass, up to 10% of gravel 19,0 mm and sand, which would give rise to two alternative traces, in addition to the reference composition. After mixing the aggregates, the fresh concrete in the three traces was submitted to the slump test, which was zero in all cases, indicating that it was working with a dry type concrete. Then, in the hardened state, it was separated into the formats of cylindrical specimens and blocks pavers, being the tests of resistance to compression, water absorption, and other complementary procedures, such as visual inspection and dimensional evaluation. Regarding the water absorption test, the three traits presented individual and mean values lower than 7% and 6%, respectively, which is recommended. In the test of compressive strength, in the format of cylindrical specimens, the trait with 10% substitution of gravel 19,0 mm presented, at 28 days, a higher value (25,14 MPa) than that of the reference trait (22,43 MPa), while the sand substitution traced gave a practically identical value (22,40 MPa), which is quite satisfactory for the research. As a complement, a statistical ANOVA analysis of the results of compressive strength and water absorption was carried out, followed by the Duncan test. Also proceeded to scale, through empirical methods, of an idealized interlocking pavement with a consequential comparative cost analysis and it turned out that the use of alternate stroke with 10% substitution of sand made the structure be cheaper. It is concluded that the results obtained, from the experimental program, encourage the use of bottom ashes on interlocked concrete pavements.