Environmentally friendly concrete block production: valorization of civil construction and chemical industry waste

In the present work, a study was carried out on the dosage of wastes from the chemical industry (tannery sludge) and civil construction (concrete and plaster) in mixtures used in concrete blocks' production. The objective was the application of these blocks in paving. The characterization of the materials used was performed employing X-ray diffractometry (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The effect of the different residues on the blocks' properties was evaluated through compressive strength, flexion-traction, water absorption, abrasion resistance, and leaching tests. The results indicated that the concrete paving blocks produced with the addition of residues did not obtain gains in the values of mechanical resistance to compression and traction in bending compared to blocks made with standard raw material. However, the blocks produced with construction waste presented satisfactory results for application in street paving after 7 days of concrete curing, reaching values between 36.54 and 44.6 MPa for the mentioned properties. These values also increased to 21.4% within 28 days of curing. The blocks produced with plaster showed values between 37.03 and 39.85 MPa after 28 days of curing, allowing their use for street paving. On the other hand, the blocks containing residues from the chemical industry had lower strengths, reaching a maximum of 29.36 MPa after 28 days of curing. In addition, it was also noted that the blocks produced with recycled concrete showed an improvement in performance for a composition of 50% recycled material.