The incorporation of a recycled concrete aggregate (RCA) as a replacement of natural aggregates (NA) in road construction has been the subject of recent research. This tendency promotes sustainability, but its use depends mainly on the final product’s properties, such as chemical stability. This study evaluates the physical and chemical properties of RCAs from two different sources in comparison with the performance of NA. One RCA was obtained from the demolition of a building (recycled concrete aggregate of a building—RCAB) and another RCA from the rehabilitation of a Portland cement concrete pavement (recycled concrete aggregate from a pavement—RCAP). Characterization techniques such as X-ray fluorescence (XRF), X-ray diffraction (XRD), UV spectroscopy, and atomic absorption spectrometry were used to evaluate the RCAs’ coarse fractions for chemical potential effects on asphalt mixtures. NA was replaced with RCA at 15%, 30%, and 45% for each size of the coarse fractions (retained 19.0, 12.5, 9.5, and 4.75 sieves in mm). The mineralogical characterization results indicated the presence of quartz (SiO2) and calcite (CaCO3) as the most significant constituents of the aggregates. XFR showed that RCAs have lower levels of CaO and Al2O3 concerning NA. Potential reactions in asphalt mixtures by nitration, sulfonation, amination of organic compounds, and reactions by alkaline activation in the aggregates were discarded due to the minimum concentration of components such as NO2, (–SO3H), (–SO2Cl), and (Na) in the aggregates. Finally, this research concludes that studied RCAs might be used as replacements of coarse aggregate in asphalt mixtures since chemical properties do not affect the overall chemical stability of the asphalt mixture.

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Engine oil is one of the key elements to protect and to increase the life of the lubricated engine parts. However, it gets contaminated by external particles either in filtration or during combustion, which produces deterioration in some of the engine parts which are being lubricated. In that sense, delays and very expensive repairs are generated at the maintenance workshops due to the high contamination in oils and to the late detection of the deteriorated parts. This work presents an analysis of used oils, extracted from hot and cold engines of 2.5-liter engine pick-up trucks, by using the two methods of the X-ray fluorescence technique (XRF): standard-less and calibrated, in order to determine the elements present and to establish the engine parts that wear out more easily and thus, to help with predictive maintenance of the trucks. The results are also useful for comparison purposes and to evaluate the effectiveness of the XRF technique in analyzing these types of samples.

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