Avaliação da resistência à fratura e susceptibilidade ao dano por umidade de misturas asfálticas com elevados teores de escórias de aciaria

Abstract

The construction industry demands significant quantities of natural resources, but it also has a strong potential for utilizing by products from other production processes. As an example, consider the steel production sector, which generates a significant amount of coproducts and waste each year, such as steel slag. Due to its favorable physical and mechanical characteristics, its use as an aggregate in asphalt mixtures has been evaluated. However, its expansive nature can hinder its use as an aggregate in pavement. These effects can manifest in the short and long term, either due to moisture or temperature, leading to problems such as premature cracking or moisture-induced damage.Therefore, this research aims to evaluate the effects of the expansion of these materials on the fracture resistance and moisture damage of aged asphalt mixtures in the short and long term, containing high levels of LD steel slag. To achieve this, physical and chemical characterization tests of two samples of slag (cured and uncured) were conducted to infer the effects of expansion on the individual characteristics of the material. Subsequently, dosage studies of three types of asphalt mixtures (a reference mixture with 100% natural aggregate and two mixtures containing 40% LD slag, varying the level of slag expansion) were carried out. Finally, compacted asphalt mixtures were subjected to mechanical tests such as Diametral Compression Tensile Strength (IDT), Moisture-Induced Damage (MID), and Semi-Circular Bend (SCB) Fracture Test. Additionally, an adapted PTM test for asphalt mixtures with high levels of natural aggregate replacement by this byproduct was performed to assess the minimization or otherwise of the expansive effect of the slag due to the asphalt binder film covering the aggregate.The results indicated that the expansion process indeed alters its physical and chemical properties, with a focus on absorption. Mixtures containing LD slag showed satisfactory IDT values and better MID resistance, especially in the short term, compared to mixtures containing only natural aggregate. Regarding fracture parameters, LD-containing mixtures exhibited greater resistance to rupture and a higher ability to absorb energy before failure compared to mixtures without slag, along with good flexibility under loading, especially for mixtures with uncured slag. Overall, it was observed that asphalt mixtures with high percentages of LD slag demonstrated mechanical performance comparable to or better than mixtures containing only natural aggregate.