ENVIRONMENT: Green Roads Start Rolling Out
Recent Western Cape Business News
THE establishment of a Greenroads rating system – similar to that employed by the Green Buildings Council of SA - was discussed at the recent Conference on Asphalt Pavements for Southern Africa (CAPSA).
SSI Engineers & Environmental Consultants has been instrumental in bringing the Greenroads principles to South Africa having been involved with the USA based Greenroads Foundation for over a year and having recently concluded a memorandum of understanding with the foundation to localise the tool for South African conditions.
Greenroads is a collection of sustainability best practices, also known as credits which relate to the design and construction of roads. A company will receive credits for employing sustainable practices in the design and construction of roads, such as using reclaimed materials from existing pavements in rehabilitation, rather than new materials, or moving from hot-mix to warm-mix asphalt thereby lowering the carbon footprint of the project whilst minimising the environmental impact.
Delegates attending the CAPSA conference agreed that there was a need for a Greenroads certification scheme in South Africa, which will be used as a tool to assess the sustainability of road projects in the country.
A representative of the international Greenroads Foundation provided delegates with insight and information on how the system works in the USA.
Although an SSI initiative, the intention is to develop a true industry standard which requires the involvement and buy-in of as broad a spectrum of the roads industry as possible. Although the implementation of a Greenroads system is still a year away, SSI is considering applying the principles on a current project as a pilot for possible inclusion in a future Greenroads rating system.
An example of the ‘Green Roads’ technique is on the M5 in Durban where recovered existing asphalt was crushed, screened and stabilised and then placed on the roadway in a 150mm-thick layer followed by a 60mm thick asphalt-wearing course as the final surfacing.
SSI resident engineer Peter Jerome explained that only recycled asphalt materials were used, resulting in significant cost savings on the project. All asphalt recovered for reuse includes a 100%-recycled bitumen stabilised materials (BSM) layer, milled off asphalt haunch and recycled concrete kerbs. About 15% of the recycled asphalt added to the asphalt surfacing is delivered as Warm Mix Asphalt (WMA).
The benefits of using WMA at lower temperatures include a reduction in energy consumption, greenhouse-gas emissions, fumes, and odours generated at the plant and the paving site. Less obvious technical benefits include the reduction of short-term binder hardening, the reduction of mixture tenderness and a possible increase in the percentage of reclaimed asphalt pavement used in new asphalt pavement mixes.
SSI says it has embraced the principles of the Greenroads imitative and is actively promoting its adoption as an industry standard in South Africa.
Sustainable practices in the design and construction of roads, such as moving from hot-mix asphalt to warm-mix asphalt or using reclaimed materials from existing pavements in rehabilitation, rather than new materials, will minimise the environmental impact and lower the carbon footprint of projects.
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