Paving the way for rubberised roads

August 14, 2017

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Rubberised roads demonstrate a viable solution against greenhouse gas emissions, road noise abatement and landfilling of scrap tyre rubber. In Thailand, rubber roads also stabilise its economy, says Angelica Buan in this report.

Traffic on roads, the blight of economic growth, has health, environmental and productivity costs. INRIX, a US-headquartered mobility intelligence company that provides traffic analytics and population movement insights, indicated in its 2016 scorecard report that among developing countries surveyed, Thailand, which also ranks first worldwide, leads in peak hours spent in congestion, with an average of 61 hours.

Meanwhile, Russia leads in the developed countries category and ranks fourth worldwide with an average of 42 hours spent – and wasted – in traffic jams. On the other hand, people in countries like Italy and Singapore spend fewer hours on roads, averaging 15 and 10 hours, respectively.

The growing population and urbanisation are also major causes of road congestion, according to INRIX. It is a crisis that is also tied up with the state of infrastructure of a given region, country or city. In other words, road congestion is a malaise that has not found a perfect cure, as yet. However, there is something that can be done to cure its symptoms: among which is road noise.

Keeping the level of noise down on roads

How to dampen road noise is the main objective of a European project called Persuade. Launched from 2009 to 2015, the EUR3.4 million, 12-partner consortium focused on developing and testing new road pavements with very high noise-reducing effect. They recommended a formula for poroelastic road surfaces (PERS) that are based on recycled tyre rubber, and with a high proportion of air voids to make the surface porous.

The air voids in combination with the elastic rubber granules to make the surface flexible, contribute to dampening noise from the tyre-road contact. PERS may be used on limited areas with very high noise exposure, and where it is not possible or desirable to use noise barriers.

road

Persuade further explained that by using rubber granulate from used vehicle tyres bound with elastic resin, specifically for this project, a two-fold environmental aim may be achieved: reduce noise from road traffic and at the same time give a considerable amount of used tyres in Europe a second lifecycle. The final mixtures produced in this project might include also a certain amount of sand or stone aggregate, mainly to increase friction.

PERS has been initiated in Belgium, Denmark, Poland, Slovenia and Sweden, where full-scale test tracks with different stone/rubber/binder mixes of varying length were built; and on roads carrying different traffic loads.

Large amounts of recycled rubber from scrap tyres were used. The Persuade team also monitored the tracks for a variety of parameters, such as skid resistance, winter behaviour, noise reduction and durability.

According to the team, it “achieved initial tyre/road noise reductions around 10 dB with the best PERS materials, exceeding that of average noise barriers. All the materials tested on roads exposed to traffic met road administration requirements concerning skid resistance. Performance during winter conditions was also acceptable overall. Procedures to handle early snowfall and ice formation events were developed, including preventive and extra salting”.

Another important advantage of the materials used in PERS is that they do not create chemical hazards during construction or operation, Persuade reported.

US test driving improvements in rubber-asphalt mix

The US piloted asphalt-rubber road technology in 1948 with a mile-long span along Exchange Street in Akron, Ohio. It was befitting since Akron was dubbed the “Rubber Capital of the World”, being a home base to the world’s top tyre brands like BF Goodrich, Bridgestone, Firestone, General Tire and Goodyear.

That first test drive for elastic road mix contained between 5% to 7% rubber additive and the remaining bulk with asphalt. It was only in 1965 that crumb rubber was incorporated to asphalt mix, repurposing waste tyres. Since then, the state has adopted wider use of rubberised asphalt, building what it calls “quiet roads” with decibel level of road noise reduced to as much as 12%.

crumb-rubber

Meanwhile, rubber roads are also flourishing in other US states, aided by new R&D in the technology. In 2014, a five-year study funded by the National Science Foundation aimed at improving the crumb rubber-asphalt process.

Magdy Abdelrahman, Associate Professor of civil engineering at North Dakota State University experimented with crumb rubber and other components. His research involved studying interaction of crumb rubber with specific additives to evaluate and characterise the physical and chemical properties of the compounds. He also wanted to determine whether certain conditions, such as bad weather, would cause chemical releases from the recycled materials and the potential impact on soil and groundwater.

In Canada, a more recent breakthrough has come from the University of British Columbia (UBC) engineers who developed a type of concrete using recycled tyres. The material, more resilient in its class, could be used not only for roads but also for other structures like buildings, dams and bridges.

To formulate the desired concoction that includes 0.35% tyre fibres, the researchers experimented combining different proportions of recycled tyre fibres and other materials used in concrete, such as cement, sand and water.

According to the research team, the laboratory tests showed that fibre-reinforced concrete reduces crack formation by more than 90%, compared to regular concrete, with polymer fibres bridging the cracks as they form, helping protect the structure and making it last longer.

This year, the rubberised concrete has been used to resurface the steps in front of the McMillan building on UBC’s campus. Having monitored the performance of the concrete using sensors embedded in the concrete, the research team said it showed a significantly reduced cracking.

Rubberised roads boost latex consumption in Thailand

The 69-million populated Thailand is witnessing an ever-booming economy, which stands to grow at 3.2% in 2017, according to the World Bank. That being said, the country’s saga with road congestion continues.

Nevertheless, being a major rubber producer and automotive hub in Southeast Asia, the country is also paving roads with rubber. And the reasons are spawning beyond cutting down traffic noise and improving road conditions.

As the world’s largest rubber producer and exporter of rubber, Thailand is contending with falling prices of the commodity amid oversupply from other rubber producing countries. The country accounts for 4.5 million tonnes/year of rubber produced or 37% of global production.

To stimulate its latex prices, it is boosting its domestic consumption. In its latest bid to promote rubberised roads, Thailand’s Songkhla province is adding six more in the districts of Chana, Saba Yoi, Rattaphum, Na Mom and Thepa, to its existing two rubberised roads located in Hat Yai and Khuan Niang districts. Each of the two 4-lane roads, spanning 1.85 km and 1.5 km, respectively, is 8 m wide; and 1 km of the 5 cm-thick road uses 2.5 tonnes of latex.

The new construction will range from 1.5 km-2 km long and cost 5 million baht/km or about 20% more than surfacing with asphalt road at 4 million baht/km. Nevertheless, officials claim that the rubberised roads are cost effective, lasting to about 5-7 years.

Citing a current report from the Department of Rural Roads, already 7,000 tonnes of latex have been used for road construction projects in Thailand, for the year.

road-rubberized

The volume of rubber used is worth over 358 million baht. Since 2013, it reported that over 22,000 tonnes of raw latex, worth more than 1 billion baht, has been used for road construction and repairs.

For Thailand, not only does using latex rubber enhance the durability of roads, and renders lower road maintenance costs, but it also cushions rubber prices by increasing its domestic use and consumption of the rubber it produces.

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International Rubber Prices
(as of 14, November 2017)

Monthly The prices shown above do not include VAT @4% on purchase and expenses towards packing, transportation, warehousing  and other incidentals


Source: India Rubber Board

Automotive

PRA ELECTRONIC ISSUE 2017
November/December 2017 Issue

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