Using reclaimed concrete in road construction

This case study examines the 2017 upgrade of the N2 highway near Borcherd’s Quarry in Cape Town, focusing on the reuse of 13,000 m3 of concrete and 5,000 m3 of asphalt millings as reclaimed aggregate for the road's base layers.

• The project successfully diverted waste from landfills, saving City of Cape Town airspace valued at R3.1 million, though this figure excludes operational cost savings from avoiding the landfilling process.
• The financial viability of using recycled material was heavily impacted by the location of the crushing site. While on-site crushing would have yielded a 36% cost saving compared to virgin material, moving the crusher to Philippi made the recycled material 20% more expensive than virgin commercial sources.
• Technical recommendations for reclaimed aggregate include crushing to 37 mm for G5 material and achieving a grading modulus of 2.2-2.3. The project's actual grading modulus of 2.6 made the material harder to test and work with; reducing this to 2.2-2.3 via secondary crushing and blending could increase CBR values from 28-30% to 70-80%.
• Regarding materials testing, SANS 3001 is recommended over TMH1 because it is more conservative. In this project, the same material tested as G4 under TMH but as G5 under SANS.
• The project demonstrated that required material performance can be achieved even when asphalt millings are included in the mix, despite contractors typically avoiding asphalt mixes due to a lack of cohesion between particles and a resulting decline in CBRs at lower compactions.

APA

Barnes, D. K. (2019). Using reclaimed concrete in road construction. GreenCape. https://greencape.co.za/wp-content/uploads/2022/10/N2-ReclaimedConcrete-CS-v4WEB-3.pdf

Chicago

Barnes, Dr. Kirsten. Using reclaimed concrete in road construction. GreenCape, 2019. https://greencape.co.za/wp-content/uploads/2022/10/N2-ReclaimedConcrete-CS-v4WEB-3.pdf.

Wikipedia

{{cite report |last1=Barnes |first1=Dr. Kirsten |title=Using reclaimed concrete in road construction |publisher=GreenCape |date=2019 |url=https://greencape.co.za/wp-content/uploads/2022/10/N2-ReclaimedConcrete-CS-v4WEB-3.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{barnes2019using, author = {Barnes, Dr. Kirsten}, title = {{Using reclaimed concrete in road construction}}, institution = {GreenCape}, year = {2019}, url = {https://greencape.co.za/wp-content/uploads/2022/10/N2-ReclaimedConcrete-CS-v4WEB-3.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }