Utilization of Waste Plastic as a Strength Modifier in Surface Course of Flexible and Rigid Pavements Afroz Sultana.SK1, K.S.B.Prasad2
PG student, Department of civil engineering, GMR Institute of Technology, Rajam, Andhra Pradesh, India Assistant professor, Dept. of civil engineering, GMR Institute of Technology, Rajam, Andhra Pradesh, India
The present study investigates the potential use of waste plastic as a modifier for asphalt concrete and cement concrete pavement. Plastic waste, consisting of carry bags, cups etc can be used as a coating over aggregate and this coated stone can be used for road construction. Different ratios of plastic such as Polypropylene (PP), Low Density Polyethylene (LDPE), and High Density Polyethylene (HDPE) by weight of asphalt were blended with 80/100 paving grade asphalt. Unmodified and modified asphalt binders were subjected to rheological test. The performance tests including, Marshall Stability, loss of stability tests were conducted using plastic coated aggregates and polymer modified bitumen on HMA mixtures. Work has been done by using plastic coated aggregates in cement concrete pavements. The results showed better values for asphalt concrete. This is an eco-friendly process.
Key Words - waste polymer, Hot Mix Asphalt
(HMA), plastic coated aggregates, polymer modified bitumen, Marshall Stability, M20 plain cement concrete.
One of the main components of hot mix asphalt (HMA) is asphalt cement binder. Asphalt is used primarily construction of roads and as a major component in roofing materials due to its remarkable binding and waterproofing properties. The behavior of asphalt cement in service is governed by their initial engineering properties as well as by the mechanical and environmental conditions to which they are subjected. The steady increase in high traffic intensity in terms of commercial vehicles, the increase in over loading of trucks and the significant variation in daily and seasonal temperature demand improved road characteristics. Under these situations, it is essential to modify the asphalt cement using modifiers to improve its engineering properties. On the other hand, the environmental problem such as disposal of waste plastic is major concern. To overcome the problems the modifiers (waste plastic) are used. Among various types of modifiers, polymers are probably the most promising.
Despite the large number of polymeric products, relatively few are suitable for modification of asphalt cement and are compatible with asphalt cement. Polymers used for asphalt modification can be grouped into three main categories: thermoplastic elastomers, plastomers, and reactive polymers. Thermoplastic elastomers are obviously able to confer good elastic properties on the modified binder; while plastomers and reactive polymers are added to improve rigidity and reduce deformations under load .The following are some of the examples of polymers. SBS (radial and linear) – good fatigue resistance, high creep rate, but oxidation susceptibility. PE – high thermal extension but low stiffness. SBR – very good aging and weather resistance but low tear strength, low ozone resistance, oxidation susceptibility. Polybutadiene (PB) – excellent wear resistance, impact resilience, but low strength. PP – good chemical resistance, good fatigue resistance but oxidative degradation, high mould shrinkage and thermal expansion was observed. The vigorous tests at the laboratory level proved that the bituminous concrete mixes prepared using the treated bitumen binder fulfilled all the specified Marshall mix design criteria for surface course of road pavement. There was a substantial increase in Marshall Stability value of the BC mix, in the order of two to three times...