Paint booth waste as an alternative aggregate for the production of interlocking concrete blocks

Inadequate disposal of hazardous waste results risks to the environment and human health. Although the use of hazardous waste in new processes and/or products has received limited attention in the literature, there is still significant potential to be investigated. Reducing the usage of natural resources and waste management are important for sustainable practices during concrete production. This study investigated the mechanical and leaching behavior of paint booth waste (PBW) as a partial substitute (10, 20, 30 and 40%) of coarse aggregate in concrete mixtures for the manufacture of interlocking blocks. A sample of PBW used in this research differs from those in the literature due to its granulometry characterized by aggregates of different sizes. Concrete consistency, compressive strength, water absorption, X-ray diffraction, scanning electron microscopy, and leaching tests were carried out. The PBW did not influence the consistency in the fresh state of the concrete. The blocks with smaller substitutions (10 and 20%) presented denser structures and with greater strengths, surpassing 35 MPa after 28 days. Higher levels of PBW resulted in more porous concrete blocks with greater water absorption. The concrete-PBW mixtures showed no metal toxicity, i.e., the incorporation of this waste in the construction material avoided metal leaching. Concrete blocks with up to 20% PBW demonstrated satisfactory mechanical and environmental performance.