Concreto leve contendo espuma de poliuretano reciclada e adições minerais

Abstract

One alternative to reduce the weight of concrete is by replacing its aggregates with lighter ones, resulting in what is known as lightweight concrete. This study aimed to produce lightweight concrete by substituting the coarse aggregate with ground rigid polyurethane foam recycled and incorporating coal ash, rice husk ash, and wood ash as partial replacements for the fine aggregate. The concrete mix design followed the ABCP method, where the reference mix was obtained by volumetrically replacing the coarse aggregate with rigid polyurethane foam. Additionally, for comparative purposes, a lightweight concrete using expanded polystyrene foam recycled as the lightweight aggregate was also produced. The percentages of 5% for coal ash, 5% for rice husk ash, and 25% for wood ash were selected based on the criterion of higher compressive strength at 90 days. Subsequently, various mechanical tests (including axial compressive strength, split tensile strength, flexural tensile strength, compressive elastic modulus, and fatigue strength) and durability tests (such as water absorption by capillarity and immersion, void index, chloride penetration resistance, and wetting and drying cycles) were conducted. The results indicated that the dry specific gravity of all the concrete samples complied with the NBR 8953 (ABNT, 2015) standard. In general, the reference lightweight concrete exhibited better mechanical performance compared to the lightweight concrete with expanded polystyrene foam, and the addition of ashes to the lightweight concretes resulted in significant improvements in mechanical properties, such as compressive strength and fatigue strength. Milled rigid polyurethane foam demonstrated promising potential for enhancing compressive mechanical strength, surpassing even expanded polystyrene foam.