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.

The use of renewable energy such as photovoltaic is growing. According to IRENA, these systems are one of the most dynamic generation technologies. The global photovoltaic market has grown rapidly between 2000 and 2016 at an annual average compound rate of 44%, from 0.8 GW to 291 GW. In Colombia, regions with high solar irradiation levels have been identified as emerging markets. The Government's plan is to increase the share of non-conventional energies in the energy matrix from 2% to 8% - 10%. However, the uncertainties associated with technology and sites specific degradation rates make it difficult to calculate accurate electricity generation efficiencies and predicting future performance and material degradation rates, and thus business models exhibit considerable deviations related to the real electricity generation rates. This work studies the performance and early degradation of a 180.8 kWp rooftop on grid connected photovoltaic system, installed in Barranquilla, Colombia. Two methods were used: i) estimation of solar conversion efficiency, and ii) visual inspection. The first method includes a cross analysis of climatic conditions, irradiance levels, and the generated energy downstream the inverters. The second method consists of periodical visual inspections of installed modules to check: discoloration, delamination, busbar corrosion, cracking of solar cell, glass breakage, anti-reflection coating, and solder bond.

Atmospheric contaminants from marine-industrial environments could cause corrosion damage on steel A36 usually used in equipment and machinery. Therefore, it is desirable to study the corrosion phenomena in different micro-environments and formulate adequate protection measures. In this study, three micro-environments were selected and categorized according to ISO-12944-2 standard as C5-I and C5-M. Four multilayer-coating schemes were used on each exposure site to evaluate their performance. Corrosion products were analyzed using XRD, raman and UV-Vis techniques. The results showed that the best system was composed of a flake-filled-epoxy/polyamides/epoxy-siloxane. The results confirmed the influence of atmospheric contaminants on overall behavior from different location.