Recycling of steel slag fines for the production of autoclaved aerated concrete (AAC)

Abstract

Steel slag is a by-product of steel-making processes in which excess lime is often added to remove impurities from liquid steel. Therefore, steel slag is normally rich in calcium compounds, and it thus has the potential for the production of autoclaved aerated concrete (AAC). In this study, a steel slag from the basic oxygen furnace process was examined, and the slag fines (<4 mm) were collected and used as an AAC raw material. The slag fines were divided into four particle size ranges, that is, <0.063 mm, 0.063-0.5 mm, 0.5-2 mm, and 2-4 mm, and their effects on the physical properties of AAC products were studied. The results showed that producing AAC with the slag particles <0.5 mm was successful, and the bulk density and compressive strength of AAC specimens were decreased with the amount of slag fines used. In contrast, the slag particles >0.5 mm had volume expansion after the autoclave curing, thus resulting in cracks of AAC specimens. By reducing the particle size or precuring the slag fines with an autoclave, the problem of AAC cracking can be solved.

The Influence of Retreated Lithium Slag with a High Content of Alkali, Sulfate and Fluoride on the Composition and the Microstructure of Autoclaved Aerated Concrete

“…To improve the performance of AAC, the solid wastes were added as raw materials to the preparation of the AAC. Siliceous materials (such as ZSM-5 and iron tailing), calcareous materials (steel slag) and sulfate-containing materials (like phosphogypsum and red gypsum) were successfully utilized in the AAC [ 6 , 7 , 8 , 9 , 10 , 11 ]. However, the influence of the high-alkali, sulfate and fluoride-containing materials on the composition and the microstructure of the products in AAC has not been investigated.…”

The Influence of Disused ZSM-5 on the Performance of Phosphogypsum-Based Autoclaved Aerated Concrete

“…Thus, finding alternative raw materials is essential for the preparation of AAC. Many studies have confirmed that industrial waste can be used as feedstock for AAC production, such as graphite tailings, iron ore tailings, blast furnace slag, steel-making slag, waste red gypsum, and zeolites [4,[11][12][13][14][15]. There are also some other types of mining waste which could be utilized within concrete composites of different purposes [16,17].…”