Road Surfacing Industry goes green
“A good road network is one of the main drivers of economic development, ensuring a better quality of life for people via safe and efficient corridors for transporting goods and services locally and internationally.” Says Mr Hugues de Champs, Managing Director of Colas South Africa (Pty) Ltd. 
In the light of the global warming challenges facing all nations, whilst at COP15 late in 2009, President Jacob Zuma placed his qualified support behind an objective to decrease the country’s greenhouse gas emissions by 34 percent below “business as usual” levels anticipated for 2020. The road surfacing industry, along with all the others, are pondering this challenge and currently critically examining their operations, practices and methods.
The road surfacing industry has a solution at hand to lower the energy consumed by the construction and renovation of the nation’s road network. South Africa has traditionally been a hot applied bituminous technology country, but developments internationally are leading to strong interest in the use of cold-based techniques which includes the use of bitumen emulsions. This means much less consumption of energy during the application process and consequently much lower emissions of CO2 and other greenhouse gases.
As part of the drive to reducing the carbon footprint of the South African road construction industry our road industry specifiers should be encouraged to implement established and readily available technologies, says leading bituminous road surfacing producer and supplier, COLAS South Africa.
Although bitumen emulsions are by no means new products in the market, it is widely accepted that their substitution in place of hot applied methods offers multiple HSE benefits. These include benefiting the natural environment, protecting the health and safety of road construction workers and reducing health-risks to villagers and pedestrians along our country's road network.
Recently developed software models are available allowing public and private bodies to calculate the impact of their carbon footprint of various alternative surfacing equivalents against levels of performance. In certain countries these tools are widely used by contractors to propose equivalent technical alternatives that would reduce energy consumption and CO2 emissions. This can be achieved by proposing different structures with various material alternatives such as RAP (Reclaimed asphalt), EME (Enrobé à Module Elevé) / HiMA (High Modulus Asphalt) and bitumen emulsion, etc.
- There are practical as well as multiple health, safety and environmental incentives of making the switch, wherever possible:
- Bitumen emulsions can be applied to the road at temperatures up to 150°C lower than hot applied bituminous materials.
- Much lower energy is consumed during production and application
- Volatile organic compound (VOC) emissions are hence dramatically reduced during application
- Quicker application and turnaround means less delays and increased productivity for contractors.
- Improved response to lower road surface temperatures and seasonal anomalies, allowing contractors to work under more adverse climatic conditions compared with hot methods.
- Opening of roads to traffic sooner – job done sooner.
In South Africa the estimated bitumen emulsion consumption is only 80,000 tons per annum. One million tons per annum are consumed in the USA and two million tons per annum in France alone, indicating that, as a country with a comparably extensive road network, South Africa is lagging far behind.
“It’s a matter of economics”, says Managing Director of Colas South Africa “ The environmental costs are every bit as real and tangible as economic costs so the question becomes how to encourage South Africa’s road building industry to incorporate a green component to it’s life cycle costing analysis, by optimising the use of bitumen emulsions wherever practical. At Colas, we will be showing the way forward by promoting this technology.” he concluded.
| What is an emulsion? | An emulsion is formed when very small droplets (dispersed phase) of one liquid is dispersed into another (continuous phase) liquid |
| What is a bitumen emulsion? | A bitumen emulsion is a microscopically sized dispersion of bitumen droplets in water, in the presence of a chemical emulsifier. |
| How is bitumen emulsion manufactured? | In practice the dispersion of bitumen droplets in water takes places in a high speed homogenizer or colloid mill. Colas utilises an advanced in-line process plant based on the most modern technology for the manufacture of their bitumen emulsions. This in-line process ensures that material dosages and flow are continuous: the process is automatically controlled by computer via a series of flow meters thus yielding a product conforming to the most stringent quality and consistency control parameters. |
| What types of bitumen emulsions are available? | Bitumen emulsions consist of two main types namely anionic and cationic. Anionic emulsions carry a negative charge on the surface whilst cationic emulsions carry a positive charge. Due to its specific properties, the technical evolution of cationic bitumen emulsions has made it possible to manufacture very specific controlled breaking emulsions. This allows the contractor to be able to seal almost all year long if necessary. The improvement in the technology has made it possible to be able to master the increase in cohesion of the binder, and therefore allowing the road to be opened up to traffic quicker. |
| What are the advantages of bitumen emulsions? |
|
About the Firm
Commencing its operations in 1928,Colas South Africa (Pty) Ltd is part of the Indian Ocean Grouping of French holding company The Colas Group. Colas in South Africa supplies, manufactures and applies bituminous binders for road surfacing. They operate across South Africa with factories and depots in all major centres. The company also operates in Namibia, Zambia and Kenya. The company is highly regarded in the industry and is ISO9001 listed. Bitumen emulsions of the anionic and cationic types are produced locally by the company under SABS 309 and SABS 548 standards respectively.
For more information please visit www.colas.co.za
