Avaliação da estabilidade de argamassas produzidas com sucata KR

Abstract

In 2023, the Brazilian steel industry generated approximately 18.4 million tons of industrial residues, among which stands out the KR slag, a by-product from the desulfurization of hot metal using the Kambara Reactor (KR). Despite its potential, this material remains underutilized in civil construction due to concerns regarding its high sulfur content and fine particle fraction, which can affect workability and long-term durability of cement-based composites. This study aimed to assess the mechanical performance and dimensional stability of rendering mortars in which natural sand was partially or totally replaced by KR slag. Three mortar mixes were produced: a reference mix with natural sand, one with 50% sand replacement, and another with 100%. Physical, chemical, and morphological characterizations of the slag were conducted, including granulometric analysis, X-ray fluorescence (XRF), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The mortars were then evaluated in terms of consistency, compressive strength evaluation, and accelerated expansion analysis under hydrothermal conditions. The results showed that the high fines content in the KR slag increased water demand to achieve proper workability, which contributed to a notable reduction in compressive strength, particularly in the mix with 100% replacement. Nonetheless, all mixes exhibited satisfactory dimensional stability over 28 days of exposure to aggressive conditions, with no signs of cracking or internal sulfate attack. The mix with 50% KR slag replacement demonstrated balanced performance and showed potential for nonstructural applications, such as coatings and plasters, where cohesion and adherence are critical parameters. Incorporating KR slag as a fine aggregate emerges as a technically feasible and environmentally responsible alternative that aligns with circular economy practices in the construction industry.