Construction Materials from Stainless Steel Slags: Technical Aspects, Environmental Benefits, and Economic Opportunities

Abstract

Summary State‐of‐the‐art technologies that implement theindustrial ecology concept only make it to the market if environmental gains and economic benefits are significant. Therefore, the article investigates, in an interdisciplinary way, two innovative technologies that valorize stainless steel (SS) slags as block masonry (bricks): carbonation and thermo‐alkali‐activation. The technical, environmental, and economic features of three SS bricks—solid bricks, perforated bricks, and lightweight aerated blocks—are compared to commercially available construction materials. Although the produced bricks meet industrial standards, technical challenges, such as optimization of alkali addition and use of metal molds, should be dealt with before upscaling to industrial production. A cradle‐to‐gate life cycle assessment that aggregates the results of the various impact categories shows that the environmental impact of solid and perforated SS bricks is lower than the impact of conventional clay‐baked bricks owing to the avoidance of additives for slag stabilization and energy consumption for sintering clay. The impact of aerated SS bricks was found to be similar to the commercially available aerated blocks. More specifically, the carbon dioxide uptake from carbonation reduces the overall environmental impact, whereas use of alkalis increases the impact. A strengths weaknesses opportunity threats analysis highlights the economic advantages of SS bricks originating from lower energy requirements, reduced dependence on primary resources, and improved metal recovery from slag. However, in order to apply the innovative technologies at industrial scale, challenges related to processing conditions, feedstock variability, and potential competition from existing brick suppliers have to be overcome.

A Review of Circular Economy Prospects for Stainless Steelmaking Slags

“…In general, several steel slags have beneficial properties such as good strength, durability, and latent pozzolanic (cementitious) properties that make them attractive and potentially suitable for engineering applications, such as infrastructure construction, soil stabilization, neutralizer, as filler or binder in concrete or as drainage or low-permeability barrier layers [61][62][63][64][65][66][67]. Slags from stainless steelmaking are potential as well provided that the best suitable slag type is selected and modified by appropriate additions, cooling method, or other pre-treatments, i.e., tailoring for each specific application.…”

A Roadmap for Production of Cement and Concrete with Low-CO2 Emissions

“…Such primary resources include clays with lower purity than industrial clays [16,157]. Secondary resources may include industrial by-products, including slags from metal ore beneficiation processes [158,159], as well as post-consumer wastes such as ashes from incinerators [160,161]. Since these resources have different chemistry to conventional raw materials for PC production, high substitution rates of these resources for PC clinker can significantly modify solid phase stabilities in the resulting binders.…”

Waste blast furnace slags as raw materials for the production of binders

“…Авторами роботи [3] з вивчення шлаків, які використовуються в будівництві, вивчені такі властивості: гідратація, реактивність, гідравлічна активність, рН, вміст скла, мікроструктура. У роботі [4] наводиться можливість використання шлаків виробництва неіржавкої сталі як блокової кладки (цегла) після попередньої карбонізації та термо-лужної активації. Відвальні доменні шлаки як побічний продукт вторинного рафінування сталі запропоновано використовувати [5] як в'яжучу речовину будівельних розчинів під час замінювання гідравлічного вапна.…”