Abstract
In this paper, a permeable steel-slag–bitumen mixture (PSSBM) was first prepared according to the designed mixture ratio. Then, the interaction characteristics between steel slag and bitumen were studied. The chemical interaction between bitumen and steel slag was explored with a Fourier-transform infrared spectrometer (FT-IR). The influence of steel-slag chemistry, mineral composition, and bitumen reaction on phase angle, complex shear modulus (CSM), and rutting factor was explored with dynamic shear rheological (DSR) tests. The PSSBM had better properties, including high permeability, water stability, Marshall stability, high-temperature (HT) stability, and low volume-expansion rate. Bitumen-coated steel slag can prevent heavy-metal ions from leaching. In the infrared spectra of the mixture of a chemical component of steel slag (calcium oxide) and bitumen, a new absorption peak at 3645 cm−1 was ascribed to the SiO–H stretching vibration, indicating that new organic silicon compounds were produced in the chemical reaction between calcium oxide and bitumen. SiO–H had an obvious enhancement effect on the interfacial adhesion and high-temperature rheological property of the mixture. In the mineral components of steel slag, dicalcium and tricalcium silicate reacted with bitumen and generated new substances. Chemical reactions between tricalcium silicate and bitumen were significant and had obvious enhancement effects on interfacial adhesion and high-temperature rheological properties of the mixture. The results of FT-IR and DSR were basically consistent, which revealed the chemical-reaction mechanism between steel-slag microcomponents and bitumen at the interface. SEM results showed that pits and grooves on the surface of the steel-slag aggregate, and the textural characteristics provide a framework-like function, thus strengthening the strength and adhesion of the steel-slag–bitumen aggregate interface.
Highlights
Due to the shortage of natural stone and the increase in manufacturing costs of high-quality aggregates in China, the comprehensive utilization of metallurgical steel slag in preparing aggregates has been widely considered
If steel slag can be utilized as an aggregate to prepare permeable steel-slag–bitumen concrete for pavement engineering, it can speed up the construction of ecological pavements, and enhance the resource utilization of steel slag, partially solving the shortage problem of the lack of high-quality natural-stone aggregate [11,12]
Other materials used in the study were A-90 road petroleum bitumen (An Energy Co., Ltd., Jinan, China), alumina, calcium oxide, ferric oxide, silica (A Technology Co., Ltd., Beijing, China), ferroferric oxide, dicalcium silicate, calcium silicate, RO phase, high modulus agent
Summary
Due to the shortage of natural stone and the increase in manufacturing costs of high-quality aggregates in China, the comprehensive utilization of metallurgical steel slag in preparing aggregates has been widely considered. Steel slag has high wear resistance and is suitable pavement material [1,2,3,4,5,6,7,8,9,10]. If steel slag can be utilized as an aggregate to prepare permeable steel-slag–bitumen concrete for pavement engineering, it can speed up the construction of ecological pavements, and enhance the resource utilization of steel slag, partially solving the shortage problem of the lack of high-quality natural-stone aggregate [11,12]. Kavussi et al [16] used electric-furnace slag to substitute the coarse aggregate of 2.36 mm in a limestone–bitumen mixture, and found that the crack propagation of the mixture was largely prevented due to the strong skeleton embedding and extruding effect of steel slag
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