Professors Eric Lachance Tremblay and Jean-Claude Carret have studied the potential for recycling concrete and steel residues for road rehabilitation. Discover the summary of their work.  


The main aim of the circular economy is to extend the life cycle of products or materials, through reuse and recycling for as long as possible. In the Quebec context, the circularity index is only 3.5%. One way of improving this indicator is to use road rehabilitation techniques that enable materials to be fully reused. In-place recycling, for example, is a pavement rehabilitation technique that is carried out in situ, at ambient temperature, and enables the materials in the existing pavement to be reused. This technique offers significant economic and environmental benefits, as the in-situ materials are 100% reused. 


With these aspects in mind, the aim of this project was to investigate the use and recovery of recycled materials, particularly industrial by-products, for the mechanical stabilization of pavements. The recycled materials studied were: recycled bituminous aggregates (GBR), crushed recycled concrete and steel slag. California Bearing Ratio (CBR) tests were carried out in accordance with ASTM D1883-21 under normal conditions, after soaking, and after 4 freeze-thaw cycles (FTC).  

This pilot project demonstrated that crushed recycled concrete and steel slag could be used in granular pavement foundations, particularly in in-place pavement recycling projects. Mixtures including crushed recycled concrete and steel slag showed superior results to mixtures including only GBR. In addition, the CBR value after soaking of the mix with crushed recycled concrete was found to be higher than the value before soaking. 

The next step will be to carry out further tests (resilient modulus in triaxial cells, tests which have already begun) on the granular combinations studied. It is also planned to test other combinations of these materials, varying the percentages of each component, to better understand their influence on mechanical behavior and establish guidelines for their use in pavements.  

About the project

The “ Study about the potential use of concrete residues and steel slags for cold in-place recycling of pavements” project was led by Maicon Basso Dos Santos and Sébastien Lamothe, under the supervision of Eric Lachance Tremblay and Jean-Claude Carret.   

The RRECQ is supported by the Fonds de recherche du Québec.
Fonds de recherche - Québec