The Chemical-Mineralogical Characterization of Recycled Concrete Aggregates from Different Sources and Their Potential Reactions in Asphalt Mixtures

Abstract

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.

Some Remarks towards a Better Understanding of the Use of Concrete Recycled Aggregate: A Review

“…Since the cement is produced to meet the composition required by standards [73,74], CaO and SiO 2 were concentrated at about 62% and 22%, respectively [71,[75][76][77]. For NA used in various studies, the amount of SiO 2 was in the range of about 50-63%, and CaO was mainly less than 10% [58,75,76,[78][79][80]. For RCA, which is a mixture of original aggregate and residual mortar, the SiO 2 content was lower and the CaO was higher than those of NA, distributed between ordinary Portland cement and NA [58,75,76,[78][79][80][81][82][83].…”

Evaluation of the Physical, Chemical and Environmental Properties of Ladle Furnace Slag for Their Utilization as Filler in Bituminous Mixtures

“…Based on this, several investigations have been carried out in the field of roads in which waste is used to minimize the extraction of raw materials [12]. The waste used has been diverse: ceramic dust [13], discarded plastics [14], ashes from biomasses [15], disused tyres [16], demolition aggregates [17], etc. However, in order to correctly reduce the environmental impact, it is necessary to use waste that creates a material of similar or superior quality than conventional waste.…”

Investigation on the effect of moisture induced damage on asphaltic concrete mix incorporating waste concrete aggregates

“…[1]. Concrete can be reused as recycled concrete aggregate, prepared through the crushing and grading of waste concrete, which can be wholly or partially used as a raw material in new concrete mixtures [2]. The construction industry generates approximately 900 million tonnes of building and demolition wastes.…”