Evaluation of the application of bottom ashes from thermoelectric in concrete blocks for pavements

Abstract

Considering the great generation of bottom ashes coming from a thermoelectric plant, it was decided to veri-fy the incorporation of the same in the concrete used in interlocking blocks for paving. After the collection of conventional (cement and natural aggregates) and alternative (bottom ashes) materials, environmental tests (leached and solubilized extract) were performed on the ashes and physical characterization tests (particle size analysis, real density, liquidity and plasticity limits and hygroscopic humidity) in all aggregates. By means of granulometric stabilizations, two alternative traces with ash and one reference with conventional aggregates were prepared. In all concretes, the slump value was determined in the fresh state and, in the hardened state, compressive strength and water absorption tests were performed. Pavers type I (rectangular shape) with dimensions of 10 cm ÷ 20 cm ÷ 6 cm (width ÷ length ÷ thickness) were molded and tested for compressive strength. An empirical method was also used to design an interlocking pavement designed with the mixtures investigated. It can be seen that, in the water absorption test, the three traces studied presented average results below the maximum value of 6%, which is in accordance with the regulations. With respect to the compressive strength tests, the results are lower than the minimum of 35 MPa, however it is possible to target the pavers to areas of lower traffic demand, such as bike paths. It is concluded that the results obtained, from the experimental program, demonstrate that the use of bottom ashes on interlocking concrete pavements presents potential to be exploited for commercialization purposes.