Steel slag and its applications in cement and concrete technology: A review

Recent advancements in metal–organic frameworks for green applications

The emergence of electronic devices has brought earth-shaking changes to people’s life. However, an external power source may become indispensable to the electronic devices due to the limited capacity of batteries. As one of the possible solutions for the external power sources, the triboelectric nanogenerator (TENG) provides a novel idea to the increasing number of personal electronic devices. TENG is a new type of energy collector, which has become a hot spot in the field of nanotechnology. It is widely used at the acquisition and conversion of mechanical energy to electric energy through the principle of electrostatic induction. On this basis, the TENG could be integrated with the energy storage system into a self-powered system, which can supply power to the electronic devices and make them work continuously. In this review, TENG’s basic structure as well as its working process and working mode are firstly discussed. The integration method of TENGs with energy storage systems and the related research status are then introduced in detail. At the end of this paper, we put forward some problems and discuss the prospect in the future.

Integrated energy storage system based on triboelectric nanogenerator in electronic devices

Molecular dynamics simulation of distribution and adhesion of asphalt components on steel slag

The interfacial adhesion between asphalt and steel slag aggregate is a decisive factor in the formation of an asphalt–steel slag mixture and significantly affects the quality stability of steel slag–asphalt mixtures. In this study, the adhesion between an asphalt and steel slag aggregate, the interfacial microstructure, the adsorption and desorption characteristics, and chemical reactions were, respectively, explored by a PosiTestAT–A adhesion puller, a scanning electron microscope, a net adsorption test, an infrared spectrometer, and a dynamic shear rheometer. The mechanism of adhesion between the asphalt and steel slag aggregate was analyzed from the perspectives of physical adsorption and chemical reactions. The results showed that different factors had different effects on the adhesion of asphalt–steel slag aggregate interface. The freeze–thaw cycle and steel slag aggregate particle size had significant effects on interfacial adhesion, while the asphalt heating temperature, water bath time, and stirring time had relatively weak effects on interfacial adhesion. Compared to a limestone aggregate, the steel slag–asphalt mixture had greater adhesion and better adhesion performance because the pits and textures on the surface of the steel slag aggregate produced a skeleton–like effect that strengthened the phase strength of the asphalt–slag aggregate interface, thereby improving the adhesion and increasing the physical adsorption between the asphalt and steel slag aggregate. In addition, due to the N–H stretching vibrations of the amines and amides, as well as SiO–H stretching vibrations, a chemical reaction occurred between the asphalt and steel slag aggregate, thus improving the adhesion performance between the asphalt and steel slag. Based on the shape of the adsorption isotherm, it was determined that the adsorption type was multi–molecular layer adsorption, indicating that the adhesion between the asphalt and steel slag mainly involved physical adsorption.

The Interfacial Adhesion Performance and Mechanism of a Modified Asphalt-Steel Slag Aggregate.

Steel slag is an industrial solid waste with the largest output in the world. It has the characteristics of wear resistance, good particle shape, large porosity, etc. At the same time, it has good adhesion characteristics with asphalt. If steel slag is used in asphalt pavement, it not only solves the problem of insufficient quality aggregates in asphalt concrete, but can also give full play to the high hardness and high wear resistance of steel slag to improve the performance of asphalt pavement. In this study, a steel slag aggregate was mixed with road petroleum asphalt to prepare a permeable steel slag–asphalt mixture, which was then compared with the permeable limestone–asphalt mixture. According to the Technical Regulations for Permeable Asphalt Pavement (CJJT 190-2012), the permeability, water stability, and Marshall stability of the prepared asphalt mixtures were tested and analyzed. In addition, the high-temperature stability and expansibility were analyzed according to the Experimental Regulations for Highway Engineering Asphalt and Asphalt Mixture (JTG E20-2011). The chemical composition of the steel slag was tested and analyzed by X-ray fluorescence spectrometer (XRF). The mineral composition of the steel slag was tested and analyzed by X-ray diffractometer (XRD). The asphalt was analyzed by Fourier transform infrared spectroscopy (FTIR). The results show that the steel slag asphalt permeable mixture had good permeability, water stability, and Marshall stability, as well as good high-temperature stability and a low expansion rate. The main mineral composition was ferroferric oxide, the RO phase (RO phase is a broad solid solution formed by melting FeO, MgO, and other divalent metal oxides such as MnO), dicalcium silicate, and tricalcium silicate. In the main chemical composition of steel slag, there was no chemical reaction between aluminum oxide, calcium oxide, silicon dioxide, and asphalt, while ferric oxide chemically reacted with asphalt and formed new organosilicon compounds. The main mineral composition of the steel slag (i.e., triiron tetroxide, dicalcium silicate, and tricalcium silicate) reacted chemically with the asphalt and produced new substances. There was no chemical reaction between the RO phase and asphalt.

https://www.mdpi.com/1996-1944/12/21/3603/pdf

Properties of a Steel Slag-Permeable Asphalt Mixture and the Reaction of the Steel Slag-Asphalt Interface.

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.

https://www.mdpi.com/1996-1944/13/17/3885/pdf

Effects of Steel-Slag Components on Interfacial-Reaction Characteristics of Permeable Steel-Slag-Bitumen Mixture.

The invention provides a single-grading-particle-size steel slag permeable asphalt mixture which is formed by mixing an aggregate, a high-modulus agent and rubber asphalt. The aggregate consists of single-grading-particle-size steel slag and a packing, the particle sizes of the single-grading-particle-size steel slag are 2.36-4.75 mm, 4.75-9.5 mm, 9.5-13.2 mm and 13.2-16 mm respectively, the packing is rock mineral powder, fine steel slag powder, composite cement or pulverized fuel ash, the contents of the groups of the single-grading-particle-size steel slag and the packing in Marshall test pieces are 84.40-86.14% and 7.5% respectively, and the asphalt-aggregate ratio of the steel slag permeable asphalt mixture is designed to be 6.4, 6.7, 7.0 and 7.3 respectively. The single-grading-particle-size steel slag is used for replacing parts or whole of the aggregate, the high-modulus agent and the rubber asphalt are added, the porosity of the prepared steel slag permeable asphalt mixture meets the requirements, and the single-grading-particle-size steel slag permeable asphalt mixture has higher Marshall stability, smaller analysis leakage loss and cantabro flyoff rate.

Wenhuan Liu

Papers

The Interfacial Adhesion Performance and Mechanism of a Modified Asphalt-Steel Slag Aggregate.

Properties of a Steel Slag-Permeable Asphalt Mixture and the Reaction of the Steel Slag-Asphalt Interface.

Effects of Steel-Slag Components on Interfacial-Reaction Characteristics of Permeable Steel-Slag-Bitumen Mixture.

Single-grading-particle-size steel slag permeable asphalt mixture

The synthesis of Bi12GeO20/Ag3PO4 nanowire composite for increased photocatalytic activity and decreased electron/hole recombination