Effect of acid‐activation on CaO existential state and reactive properties of hot‐splashed steel slag in cement‐based materials

Abstract

The over-burnt free-CaO(f-CaO) existential state in hot-splashed steel slag is understood by observing the microstructure of steel slag section and analyzing the minerals in the steel slag (SS). In the investigation, a new method of using hydrochloric acid as the solvent to modify the steel slag powder (SSP) is put forward. The effects of hydrochloric acid pretreatment on the surface morphology of SS and the hydration activity and soundness of SSP blended cement are investigated. Furthermore, the failure mechanism of steel slag cement-based materials and the hydration mechanism of acid-activated steel slag (ASS) are discussed in detail. The research indicated that the optimum dosage of modified SSP is 20 wt%. At this dosage, the 7-and 28-day compressive strength of paste is nearly increased 15% compared with the untreated steel slag cementbased mortar specimens. Moreover, the acid activated SS-blended cement pastes show much better soundness performances after autoclaved curing tests when compared with corresponding pastes with SS without treatment. It provides a promising approach for efficient and safe utilization of SS as supplementary cementitious material.

Mechanical performance, microstructure, and damage model of concrete containing steel slag aggregate

“…(2) To improve the strength of the concrete, it is necessary to reduce and refine the pore sizes 38 . The hydration reaction of f‐CaO in SSA is slow, and the volume of calcium hydroxide (CH) produced by the hydration reaction of f‐CaO is 98% higher than that of f‐CaO 12,39 . The SEM result depicted in Figures 12c and 13c showed that the formation of the CH in the SSC mixture compared to the normal concrete.…”

“…38 The hydration reaction of f-CaO in SSA is slow, and the volume of calcium hydroxide (CH) produced by the hydration reaction of f-CaO is 98% higher than that of f-CaO. 12,39 The SEM result depicted in Figures 12c and 13c showed that the formation of the CH in the SSC mixture compared to the normal concrete. The low content of f-CaO in the SSA can fill the microcracks and ITZ in the later hydration reaction.…”

“…For instance, studies by Roslan et al and Abu‐Eishah et al 9,10 showed that the chemical substances contained in steel slag have the binding ability, such as C 2 S, C 3 S, and so forth that are similar to Portland cement in composition; thus, can be used as a cementitious material in cement‐based concrete. The cement composites containing steel slag can reduce the heat generated by the hydration reaction, 11,12 improve the basic mechanical properties, durability, 13 and antiwear of concrete 14 . Compared with natural sand and gravel, steel slag has a higher density and compressive strength 15 and a lower grindability index 16 .…”

Experimental study on seismic behavior of circular steel tube confined reinforced self‐stressing steel slag concrete columns

“…In the past decade, the global emissions of steel slag have exceeded 1.5 billion tons. More than 500 million tons of untreated steel slag have been accumulated, leading to occupation of lands and potential pollution of water and soil because of the alkaline leachates from steel slag 1–4 …”

“…More than 500 million tons of untreated steel slag have been accumulated, leading to occupation of lands and potential pollution of water and soil because of the alkaline leachates from steel slag. [1][2][3][4] On the other hand, the consumption of concrete in engineering construction is huge, but the natural aggregate is increasingly exhausted, which makes the search for the Discussion on this paper must be submitted within two months of the print publication. The discussion will then be published in print, along with the authors' closure, if any, approximately nine months after the print publication.…”