Production of asphalt mixes with copper industry wastes: Use of copper slag as raw material replacement

Exploring the Potential of Alternative Materials in Concrete Mixtures: Effect of Copper Slag on Mechanical Properties and Carbonation Resistance

In this study, the effect on the flowability, compressive strength, absorption, sorptivity, and carbonation resistance of concrete with different copper slag (CS) replacement ratios was investigated. For this research, four concrete mixes with different percentages of CS were made (0%, 10%, 20%, and 30% of CS as replacement of cement by volume). In addition, the microstructure was analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TG-DTG). The results shows that the incorporation of CS reduces the workability and compressive strength of the mixtures, being more significant in concrete with 30% CS. The carbonation depth of concrete with CS increases monotonically with increasing CS. In addition, the compressive strength of the carbonated (20% and 30% CS) concretes show a loss of compressive strength at 90 days of exposure when compared to their water-cured counterparts. The use of low percentages of CS does not generate a decrease in workability and its mechanical effect is not significant at prolonged ages, so the use of this waste as SCM in percentages close to 10% is a viable alternative to the sustainability of concrete and the management of this residue.

Damage Fracture Characterization of Asphalt Mixtures Considering Freeze-Thaw Cycling and Aging Effects Based on Acoustic Emission Monitoring

Freeze–thaw (F–T) cycling and aging effects are the main factors contributing to the deterioration of asphalt mixtures. The acoustic emission (AE) technique enables real-time detection regarding the evolution of internal damage in asphalt mixtures during the loading process. This study set out to investigate the effects of F–T cycling and aging on the damage characteristics of asphalt mixture under splitting loads. Firstly, the Marshall specimens were prepared and then exposed to various numbers of F–T cycles (one, three, five, and seven) and different durations of aging (short-term aging and long-term aging for 24, 72, 120 and 168 h), after which the specimens were loaded by means of indirect tensile (IDT) testing, and corresponding parameters were synchronously collected by the AE acquisition system during the fracture process. Finally, the energy, cumulative energy and peak frequency were selected to investigate the damage mechanisms of asphalt mixtures. The findings demonstrate that the AE parameters provided effective identification of the deterioration for all specimens in real-time, and that the F–T cycling and aging effects altered the damage characteristics of asphalt mixtures, causing early damage, exacerbating the formation of micro-cracks in the early stage, accelerating the expansion of macro-cracks and advancing the debonding between the asphalt and aggregates. The findings of this study provide further insight into the mechanism of F–T cycling and aging effects on the deterioration of asphalt mixture.