Sustainable Materials: A Review of Recycled Concrete Aggregate Utilization as Pavement Material

Abstract

In this paper, a comprehensive literature review was conducted on the utilization of recycled concrete aggregate (RCA), which is the dominant construction and demolition waste material, in base and subbase layers and its comparison with natural aggregate (NA). The effects of crushing on the particles as a result of the compaction on the resilient modulus, permanent deformation, and California Bearing Ratio are analyzed. The paper also contains the NA consumption and waste disposal policies of different countries, RCA standards, and the environmental-economic reasons for its use. This literature review mainly focuses on pavement layers as this is the main application of RCA in the use of recycled materials. Developing integrated construction and demolition waste management will help achieve the primary goal of preventing and reducing the generation of these wastes, both locally and globally. In this way, not only is the main purpose of preventing the increase in the production of construction and demolition waste achieved, but also the reuse and recycling of the waste materials produced are encouraged. Results show that RCA has equivalent or better performance than virgin aggregate for almost any application with proper care and process control, and can be used in unbound pavement layers or other applications requiring compaction. But it is always recommended that its mechanical properties and durability performance be evaluated with full-scale tests before use. The information provided will be useful for contractors and engineers to evaluate alternative solutions and to explore the rational use of such sustainable materials in applications.

Granular Subbase Improvement with Recycled Concrete Aggregates in Tropical Areas

“…Some studies have been carried out to evaluate and compare the properties of natural granular layers vs. granular layers with RCA replacements. From the results reported in the literature regarding mechanical properties such as the California Bearing Ratio (CBR) and the LA abrasion test, it has been determined that RCAs are comparable to NA [14], highlighting that lower strengths and higher abrasions are observed but they fulfill the standards for GSB. In terms of resilient modulus, it has been established that GB with RCA show higher results than natural aggregates [14].…”

“…From the results reported in the literature regarding mechanical properties such as the California Bearing Ratio (CBR) and the LA abrasion test, it has been determined that RCAs are comparable to NA [14], highlighting that lower strengths and higher abrasions are observed but they fulfill the standards for GSB. In terms of resilient modulus, it has been established that GB with RCA show higher results than natural aggregates [14]. In addition, they found that RCA had better mechanical properties than NA but had higher permanent deformation.…”

“…In addition, the environmental effects of the use of RCA in road construction must be considered. It has been established that the use of RCA as a replacement in highway structures reduces greenhouse gas emissions and energy use [10], [14]. The environmental savings that can be achieved with this alternative are mainly related to the production of the materials [14], [16].…”

“…It has been established that the use of RCA as a replacement in highway structures reduces greenhouse gas emissions and energy use [10], [14]. The environmental savings that can be achieved with this alternative are mainly related to the production of the materials [14], [16]. A saving of about 16% in CO2 generation has been established, when comparing the production of NA versus a 70% NA and 30% RCA mix [17].…”

“…On the other hand, another important variable in the environmental analysis of the use of RCA in pavement structures is the transportation of the material [14], [18]. Thus, when transportation is not included in the scope of the analysis, large environmental advantages are observed [19], [20].…”