Porous asphalt mixture with 100% recycled concrete aggregate

Abstract

Recycling of construction debris in Singapore is an important practice given the large amount generated annually. In order to maximise the rate of recycled concrete aggregate (RCA) generated from construction debris, porous asphalt mixture (PAM) made of 100% RCA was studied in both mechanical and functional aspects. Altogether, three designs of PAMs were evaluated, namely (a) PAM–RCA mixture comprising 100% RCA, (b) PAM–RCA–TAFPACK-Super (TPS) mixture comprising 100% RCA with enhanced asphalt binder, and (c) PAM–granite mixture comprising 100% granite, with PAM–granite mixture serving as the control. A series of laboratory tests were conducted, namely the draindown test, Cantabro test, Marshall test, permeability test, and ageing test. The results showed that PAM made of 100% RCA (PAM–RCA mixture) can offer the basic drainage function and possesses potential for low-strength application, i.e. pedestrian/cyclist pathways. Meanwhile, PAM made of 100% RCA and modified by specific additive TPS (PAM–RCA–TPS mixture) can adequately fulfil the Marshall criteria of Singapore's Land Transport Authority Standard stipulated for normal roads, indicating its potential usage in normal highway application. The results suggest the feasible application of 100% RCA in PAM.

Keywords:

• porous asphalt mixture
• recycled aggregate
• low-strength pavement
• draindown test
• Cantabro test

Acknowledgements

The authors would like to thank Shell Bitumen Singapore, Taiyu Kensetsu Co. LTD, and Samwoh Co. LTD for supplying bitumen (PEN 60/70), TAFPACK-Super (TPS), and recycled concrete aggregate (RCA), respectively. The authors also thank BE degree students in characterising some of the material properties. Lastly, gratitude goes out to Nanyang Technological University for providing financial support for the research.