Studies are on at the National Institute of Technology, Kozhikode, to investigate the improvement in the durability of roads with the introduction of bituminous mixes using plastic.

Wastes like Low-density and High-density Polyethelene (LDPE & HDPE), PET, crumb rubber and chappal waste were added in the mix.

Accordingly, it was found that waste plastic can be added to bituminous mix either by dry mixing and wet mixing to get the modified mix.  In dry mixing, the waste plastic is added to heated aggregates before adding binder. In wet mixing, the waste plastic is added to plain bitumen,  producing modified bituminous binder which is mixed with the aggregates. Tests conducted on the mixes includes the Marshall Stability Test to assess the stability of the mix at various binder contents and other volumetric properties.

Static Indirect Tensile Test to assess the resistance of the mix to rutting and moisture damage in terms of indirect tensile strength and tensile strength ratio values to assess the fatigue behaviour of the mixes were carried out.

Laboratory tests proved that mixes with waste plastic addition performed better than mixes with plain bitumen.The first field trial and test was done in a small stretch on the NIT Campus with plastic-modified bitumen and found to be performing well.

The studies were conducted to investigate the effect of both the processes as a part of the research project sponsored by the Kerala State Council for Science, Technology and Environment (KSCSTE) under the principal investigatorship of M V L R Anjaneyulu, faculty, civil engineering department, NIT.

The study was conducted to enhance durability to the highly capital and labour-intensive road construction and also to investigate the problems of the present process.

It found that, when critical environmental conditions are coupled with poor materials and heavy traffic, premature failure may result because of stripping of the bituminous binder from the aggregate particles. Addition of polymers extends the service life of the pavement surface.