Abstract:
The abundance and increase of waste tyre disposal is a serious problem that leads to
environmental pollution. Crumb rubber obtained from shredding of those scrap tires has been
proven to enhance the properties of plain bitumen since the 1840s. It can be used as cheap and
environmentally friendly modification process to minimize the damage of pavement due to
increase in service traffic density ,axle loading and low maintenance services which has
deteriorated and subjected road structures to failure more rapidly. Use of crumb rubber leads to
excellent pavement life, driving comfort and low maintenance . The rheology of CRMB depends
on the internal factors such as crumb rubber quantity, type, particle size, source and pure bitumen
composition , and external factors such as the mixing time, temperature, and also the mixing
process(dry process or wet process).
The present study aims in investigating the experimental performance of the bitumen modified
with 15% by weight of crumb rubber varying its sizes. Four different categories of size of crumb
rubber will be used , which are coarse(2.36 mm- 1.6 mm); medium size(1.6 mm- 1.18 mm); fine
(1.18 mm- 600 μm); and superfine (600 μm- 300μm). Common laboratory tests will be
performed on the modified bitumen using various sizes of crumb rubber and thus analyzed.
Marshal stability method is used for mix design. Finally a comparative study is made among the
modified bitumen samples using the various sizes of crumb rubber particles and the best size is
suggested for the modification to obtain best results.
