Quarry Southern Africa November 2017 - Page 31

SUSTAINABILITY “Companies and governments are on the lookout for ways to incorporate more recycled asphalt into road building and rehabilitation projects.” There are several technologies that enable RAP reuse in the production of fresh mix, including counter-flow dryers (100% hot recycled material); parallel-flow dryers (up to 60% hot recycled material); middle ring dryers (up to 40% recycled material); and various cold addition systems (25–40% recycled material). Kirsten Barnes is a waste economy analyst at GreenCape — a non-profit organisation established in 2010 by the Western Cape Government to support the development of the ‘green’ economy in the region. OR Tambo International Airport A paper presented at the 33rd Southern African Transport Conference (Makgoka et al., 2014) examined the use of warmed asphalt with a recycled asphalt (RA) content of 55% using a foamed bitumen process during an Airports Company South Africa (Acsa) project. At that time, this was the highest amount of recycled asphalt ever produced in an asphalt plant in South Africa. The project involved the rehabilitation of the cargo area at OR Tambo International Airport, and the use of this According to Barnes, nationally, other than the requirement to reduce waste to landfill, which is embedded within the National Environmental Management: Waste Act, 2008 (Act No. 59 of 2008), there’s no strict legislative bans or diversion targets related to C&D waste. “However,” she adds, “we expect that to change, because both the City of Cape Town and the Provincial Department of Environmental Affairs in the Western Cape have C&D waste as one of their key focus areas.” n environmentally sustainable technology resulted in massive cost savings while allowing the contractor to work effectively in a highly congested area using conventional asphalt paving and milling equipment. This approach was based on experience gained on previous Acsa projects where various environmentally sustainable asphalt products had been used effectively, including foamed treated asphalt with 35% RA, haul road with only RA with a surface emulsion treatment, and cold-mixed RA mixes with emulsion. Warmed asphalt with a recycled asphalt content of 55% was used during the rehabilitation of the cargo area at OR Tambo International Airport. Sources 1. 2. 3. Makgoka, M., Grobler, J.E., Marais, H. & Bakker, D. 2014. Environmentally sustainable use of recycled asphalt at OR Tambo International Airport. Paper presented at the 33rd Annual Southern African Transport Conference 7–10 July 2014 “Leading Transport into the Future”. CSIR International Convention Centre, Pretoria, South Africa. https://repository.up.ac.za/handle/2263/45545. Mhlongo, S.M., Abiola, O.S., Ndambuki, J.M., & Kupolati, W.K. 2014. Use of recycled asphalt materials for sustainable construction and rehabilitation of roads. Paper presented at the International Conference on Biological, Civil and Environmental Engineering (BCEE- 2014), 17–18 March 2014. Dubai, UAE. http://iicbe.org/upload/8428C0314157.pdf. Ulubeyli, S., Kazaz, A. & Arslan, V. 2017. Construction and demolition waste recycling plants revisited: Management issues. Procedia Engineering, 172:1190-1197. QUARRY SA | NOVEMBER 2017 _ 29