Bitumen and cement are the main binding agents for the construction of flexible and rigid pavement, respectively. Each type of pavement has some advantages and disadvantages. Cracking, ravelling, potholes, shoving, rutand edge break are some common pavement distresses found in present roads. Beside binding agent, aggregate and filler is required in large quantity for construction of roads. Also strengthening, repairing and rehabilitation of roads requires large amounts of aggregates and binding material. Considering these issues, there has been advancement in material science and introduction of nano-materials.Some polymer or nano-material composites are used in different industries that satisfactorily take external loads without much distress. Finally, these materials last up to 30 years in a sustainable manner. For roads free of distress, there is a need to introduce a new range of material for road construction in place of conventional materials such as aggregate, bitumen and cement. The road designed and constructed with new material should be lightweight, stronger than conventional roads,constructed in less time with minimal maintenance and longer lifespan. As per the Central Pollution Control Board (CPCB), India generates 5.6 million tonne of plastic waste annually, with Delhi accounting for a staggering 689.50 tonne a day, Chennai 429 tonne, Kolkata 426 tonne and Mumbai 408 tonne. The total plastic waste collected and recycled in the country is estimated to be 9,205 tonne per day (approximately 60 per cent of total plastic waste) and 6,137 tonne remains uncollected and littered. Properly designed and manufactured polymer-based articles play an invaluable role in traditional engineering areas such as suspension units, power transmission, electrical and thermal insulation and in loadbearing structures such as ship hulls. Polymers form the basis of plastics, rubber, fibres, adhesives and paints. These polymers in solid state have a wide range of moduli and capability to extrude in different shapes, which providesan opportunity to design new components. Under the project discussed here, an attempt will be made to design a prefabricated panel out of engineered polymers for construction of roads. Further properties will be improved through R&D to develop engineered plastic out of this base material with some additives and the engineered plastic will be used for production of a panel for road constructionapplications. Plastic as a load-bearing material The use of plastic waste in flexible pavements has opened up a solution for the problem of disposal of plastic waste. For the past two decades, ample research has been done in the area of use of plastic waste in bituminous road construction as summarised by researchers in several review papers. Kalantaret al provided a critical review on the history and benefits of using waste and virgin polymer in asphalt followed by the review of general studies on using polymers in asphalt to improve the properties of pavement. Sulymanet al provided a summary of experimental efforts on the utilisation of polyethylene terephthalate (PET) in civil engineering projects, mainly in road pavement, cements and concretes. Luzalet al presented a comparative review of recycled polymers most commonly studied as bitumen modifiers: polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), ethyl vinyl acetate (EVA), and ground tire rubber (GTR), in order to facilitate their selection and extend the use of the bitumen. The above research is related to the use of plastic (waste) with a diminutive percentage replacement of the binding material (bitumen) for road construction and this technology requires addition of aggregate. However, a prefabricated plastic road panel with zero aggregate is a relatively novel and innovative concept. The idea of prefabricated plastic roads seems inspired from the concept of plastic railway sleepers developed in 2004 and subsequently manufactured in 2006 by a Netherlands-based company, Lankhorst Mouldings (see Photo 1). The researchers have provided a detailed study to explain the effects of sleeper bending stiffness on track stiffness, railhead stability and ballast contact stresses.Photo 1: Application of plastic-based sleepers Another Netherlands-based company, PlasticRoads, is the only international player that has been rigorously working in the field of prefabricated plastic road panels. It claims to have laid the world’s first prefabricated plastic test track (30 m bike path) in the Netherlands in September 2018 (see Photo 2).Photo 2: Bike path made out ofplastic panels As the proposed concept of prefabricated plastic road panels is entirely novel for India, with only one international competitor, it is of utmost importance to explore it further to help the nation provide quick and eco-friendly (zero aggregate) plastic roads. Overall scope The project is divided into two phases; laboratory studies and field trials. Under laboratory studies, different waste plastics will be studied with different additives and polymers to develop a suitable plastic that can be further engineered so that panels/slabs can be produced. The slabs designed will be tested through field applications to ascertain their suitability in road construction. Designing:A finite element modelling approach will be used for the designing. Load, boundary conditions, geometry and material property are input parameters. Based on present expertise and understanding of material, different models will be created and compared with the present road structure. Production of prototype: Based upon initial designing, a prototype will be prepared and tested for various aspects such as loadbearing capacity, yield strength, creep test, impact test, shape deformation and thermal effects. Field testing: After the establishment of a prototype, field trials will be conducted by the construction of an actual road under control conditions such as lower traffic. Various field studies such as skid-resistance testing, impact-loading study, tyre-burst testing, flammability testing, and shape-resistant testingwill be carried out under actual load and environment conditions to evaluate the field performance. Laboratory work and interim conclusions Conventional pavement construction practices hold the drawbacks of requirement of frequent maintenance activities, delay in opening to traffic, depleting natural resources like sand and aggregates, question of sustainability in usage of cement and bitumen (Balagueraet al, 2018). These problems can be better addressed if present-day construction practices are replaced by modular-based prefabricated plastic panels. They act as easy-to-use, plug-and-play type modules. Because of the usage of recycled plastic, this solution also addresses the question of sustainability. Construction of pavement with plastic alone marks the novelty in this idea, as this construction practice does not require any conventional construction materials. Recycled waste plastic moulded into decks and sleepers has been successfully used in bridge construction, like Easter Dawyck Bridge in Scotland, and as a plastic bike path in Zwolle, Netherlands. Under the ongoing project, the feasibility of the usage of prefabricated panels was checked using the finite element modelling (FEM) analysis by comparing with conventional rigid pavement slabs. The mechanistic response is presented in Fig 1.Fig 1: Mechanistic response of the FEM analysis Beside this, the plastic granules developed for the production of the prototype are characterised in the laboratory for tensile, compressive and flexural properties. Photo 3 present various tests in progress. Also, the material is modified such that in comparison to conventional plastic, the linear burning rate is reduced from 15 mm per minute to 0.5-1 mm per minute. Photo 4 presents the testing and results. Further work is underway on the development of the prototype and application of the same in the field.Photo3: Laboratory characterisation of the developed materialPhoto 4: Burning test of the plastic Significance Construction of roads with zero aggregates is a relatively new concept. This method saves a large amount of resources and reduces damage to the environment that occurs during production of aggregates from blasting and transportation activities. Construction of roads with waste plastic will reducethe carbon footprint in construction and transportation.Owing to its lightweight nature, it will add to environment conservation as a whole. About the author:Engineer Gagandeep Singh is Principal Scientist at CSIR-CRRI, New Delhi. With experience of over 10 years in the highway industry, he has successfully contributed technically to different projects under State PWDs, NHAI, NHIDCL, CBI and private organisations.