PERFORMANCE STUDY OF SEMI DENSE BITUMINOUS CONCRETE BY ADDING POLYMER FIBERS

Abstract

Bitumen is a very complex material and durability of bitumen pavement depends upon selection of appropriate grade of
bitumen to suit the climate conditions and traffic loading. Increase in traffic density, coupled with higher wheel loads and
temperature variations lead to premature failure of bituminous course. The crack, once initiated, propagates up-wards
causing gradual weakening of the pavement. Fiber Modified Binder has been found to improve the engineering properties of
paving mixes.In the present study, tests are conducting on fibre modified and unmodified Semi Dense Bituminous Concrete
(SDBC) and various inferences obtained from the experimental investigations are discussed. Bitumen of 60/70 penetration
grade as binder and polymer fibres like polyester fibers and polypropylene fibres are used for the modification process. To
study the efficiency of the fibre modified bituminous mixes, Marshall Stability test was conducted. Various tests were also
performed on aggregate and bitumen to determine the engineering properties.The maximum Marshall Stability values
obtained in case of Polyester Fibre Modified Bituminous Mix is 15.41 KN and polypropylene fibres is 14.18 at optimum fibre
content and ordinary bituminous mix is 13.74 KN at optimum Bitumen content. From the Marshall Stability tests conducted,
an optimum fibre content of 0.3% by weight of total mix was obtained. About 12% increase in stability values can be
achieved by reinforcing the bituminous mix with polyester fibres and 3% increase can be achieved by polypropylene fibres
compared with ordinary bituminous mix. Higher stability values indicate that the modified mixes would be less susceptible to
cracking of flexible pavements. Permeability is directly proportional to the percentage of air voids so that if the air voids are
more, then the permeability will be more.