Evaluation of the Use of Coarse Recycled Rubber in Granular Subbase as a Sustainable Alternative for Pavements: Colombia Case Study

Abstract In the pursuit of sustainable solutions in construction, crumb rubber (CR) emerges as a viable alternative for enhancing road infrastructure projects. This study aims to assess the replacement of coarse crumb rubber (CCR) in a granular subbase with a maximum nominal size of 37.5 mm (known as GSB38), under Colombian conditions. The evaluated replacements of CCR were 10% and 15% by weight, and physical and mechanical tests were conducted to assess the impact of recycling on the behavior of GSB38. Additionally, to verify its sustainability as an alternative, a comparative environmental analysis was carried out between alternatives with CCR and 100% GSB38. The environmental analysis was modeled using the SimaPro tool, considering a cradle-to-gate approach. Furthermore, the assessment was conducted by applying CML-IA baseline V3.08 / EU25, which assesses 11 impacts. Savings of up to 9% were found in Acidification and Eutrophication impacts when using 10% CCR. Conversely, with 15% CCR, the maximum environmental savings observed were 5% in Eutrophication. Although the inclusion of CCR resulted in environmental improvements, it also led to a decline in mechanical performance, particularly in terms of CBR values. This reduction in strength renders the CCR alternatives unsuitable from a structural perspective. Nevertheless, from an environmental standpoint, the use of CCR represents a promising strategy for the management of rubber waste and contributes to the advancement of more sustainable construction practices, particularly in contexts where waste reuse policies are still under development.