The Process of Making Composite Plastic Roads

A city’s plastic waste is put through three tasks – cleaning, drying and shredding. The plastic waste can include anything from sweet wrappers to shopping bags.

Once all the plastic waste is shredded (a technique where all the dust particles are eliminated, and plastic items are shredded into fine pieces) these are heated at 165°c. Next, the shredded pieces are added to bitumen mix, which is also heated at 160°c. The final mix is used for constructing roads.

The inventor of the process, Vasudevan melts shredded plastic over low heat to avoid emissions (Dr Vasudevan was honoured with one of India’s highest civilian awards, the Padma Shri, for his groundbreaking research on re-using waste plastic). Polystyrene is toxic when burned but, when softened, it makes an excellent pothole filler.

“Depending on the quality of tar, a 10-30 per cent of it is replaced with the waste plastic. Since both, tar and plastic are petroleum products they gel well together,” said Asad Warsi, Swachh Bharat Mission Consultant, Indore Municipal Corporation.

Every kilometer of a plastic tar road uses the equivalent of 1 million plastic bags, saving around one tonne of asphalt and costing roughly 8% less than a conventional road. 

In experiments to find uses for discarded plastic, Dr. Vasudevan found that in a molten condition, plastic had the property of an excellent binder. Acting on the principle that like attracts like, Dr Vasudevan looked at another chemical of similar nature: bitumen, a black tarry substance that was being combined with gravel to lay roads.

“Bitumen, a highly heterogeneous mixture of hydrocarbons is in effect, composed of polymers similar to plastic,” he says. When molten plastic was added to stone and bitumen mix, Dr Vasudevan found that, true to its nature, plastic stuck fast and bound both materials together.

The bitumen-modified plastic improved the tensile strength of the road by making it more durable and flexible. Plastic also prevented pothole formation. When the layer of molten plastic filled the space between the gravel and bitumen it thwarted rain water from seeping in and causing structural defects.

When late Dr Abdul Kalam, India’s former president and scientist visited Thiagarajar College, he encouraged Dr Vasudevan to lay the first plastic paved road within the campus. In 2002, he paved a 60-ft road within the campus with plastic-modified bitumen. The road is still intact in 2018.

In 2013, The Indian Road Congress developed Guidelines for the use of waste plastic in hot bituminous mixes (dry process) in wearing courses.

The guidelines state that studies have revealed that waste plastics have great potential for use in bituminous construction as its addition in small doses, about 5-10%, by weight of bitumen helps in substantially improving the Marshall stability, strength, fatigue life and other desirable properties of bituminous mix, leading to improved longevity and pavement performance. The use of waste plastic thus contributes to construction of green roads.

Only plastic conforming to Low Density Polyethylene (LDPE), High Density Polyethylene (HDPE), PET and Polyurethane shall only be used in pavement construction.

California is a world leader in fighting climate change..

I had noticed headlines saying china was taking far reaching steps for climate change and was becoming a world leader in that area. Among the headlines was this one in 2017 : China is to stop or delay work on 151 planned and under-construction coal plants. But then I read through a recent article that said china was actually on track to add 25 % to its existing capacity to mine coal ! Given China has about half the world’s coal power capacity, the country’s coal policies have an outsized effect. This development is threatening to “seriously undermine” global climate goals, researchers have warned.

But I also read great news : In Sep this year, California Governor Jerry Brown issued an executive order calling for the entire California economy to become carbon-neutral by 2045. That is a big deal - California's economy has surpassed that of the United Kingdom to become the world's fifth largest.

Brown’s executive order directs the California Air Resources Board to work with relevant state agencies to develop a framework for implementation and accounting of progress toward statewide carbon neutrality. While state agencies can figure out a plan to achieve carbon neutrality, the state legislature will have to pass laws to implement that plan.

California cap-and-trade program, launched in 2013, is one of a suite of major policies the state is already using to lower its greenhouse gas emissions. California’s program is the fourth largest in the world, following the cap-and-trade programs of the European Union, the Republic of Korea, and the Chinese province of Guangdong.  In addition to driving emission cuts in one of the world’s largest economies, California’s program provides critical experience in creating and managing an economy-wide cap-and-trade system.

Transportation accounts for the biggest chunk of Califonria's emissions at 41%. Brown has been pushing for a transition to electric cars, signing another executive order earlier this year setting a goal of 5 million electric vehicles on the road by 2030.

Agriculture and forestry account for another 8% of California’s greenhouse gas emissions. The state is already launching a Healthy Soils Initiative to increase carbon sequestration via farming. For example, one pilot project is monitoring how much carbon will be stored by clover planted between trees at an almond orchard. The University of California at Davis is also conducting experiments to evaluate how changing livestock feed can reduce methane emissions from cattle.

India learnt lessons on disaster management..

'October 12, 2013 saw a dramatic shift in the way India perceived and handled natural calamities, like Super Cyclone Phailin. Merely three months after devastating floods in Uttarakhand state left over 15,000 people dead, Indian government acted swiftly and decisively.

Massive rescue operation ensured that every single soul, in direct line of the storm, was evacuated safely or forcefully. As Indian Meteorological Department issued a timely warning, Odisha government set a target of 'zero casualty'.

Cyclone Phailin was nearly the size of hurricane Katrina, which killed 1,200 people in 2005 and caused devastating flooding in New Orleans. It also had the wind power of 1992's hurricane Andrew, which packed 265 kph winds at landfall.

The Collectors of all seven districts like Ganjam, Gajapati, Puri, Jagatsingpur, Kendrapara, Nayagarh and Khurda were directed to start evacuation and ensure 100 per cent evacuation of people to cyclone and flood shelters and other safe places in a single day. Till the time Phailin made landfall, around 10,00,000 people had been evacuated from various districts and villages of Odisha and Andhra Pradesh.

Teams were constituted and made ready with relief and rehabilitation material. Road clearing teams were instructed to clear roads within 12 hours of the cyclone striking. Police forces were deployed in heavy numbers to ensure quick and safe passage of relief material to the affected areas. Food packets for one lakh people were arranged that could be air dropped to the most severely affected areas. Several teams of Indian Army and Navy were on the standby across the region to begin massive relief and rescue operation. 

A crucial role was played by National Disaster Relief Force - formulated under National Disaster Management Act (NDMA) of 2005. The force is gradually emerging as the most visible and vibrant multi-disciplinary, multi-skilled, high-tech force of the NDMA capable of dealing with all types of natural and man-made disasters. It appeared India had learnt its lessons well.

Block Development Officers were instructed to check all the multipurpose cyclone shelters that had been constructed, for readiness with all equipment like generators, power saws, tower lights, megaphones and utensils. Steps were taken to keep the communication systems operational. Satellite phones were issued to the District Collectors. Identification of additional schools, colleges and other public buildings that could be used as cyclone shelters and all arrangements for electricity, drinking water and temporary toilets were made. Assistance from defence forces and helicopters for rescue operation and airdropping of food packets was requested. Boats for rescue and relief operation, vehicles for evacuation and transportation of relief materials were kept in readiness. Pre-positioning of sufficient stock of fuel for vehicles was ensured.

The World Bank, appreciating the effort of the state government said that, “Successfully evacuating a million people is not a small task. This cannot be merely achieved by kicking the entire state machinery into top gear for three to four days following a cyclone warning. This has taken years of planning, construction of disaster risk mitigation infrastructure, setting up of evacuation protocols, identification of potential safe buildings and most importantly, working with communities and local organizations in setting up volunteer teams who knew exactly what needed to be done.”