INVESTIGATION ON FIBRE MODIFIED BITUMINOUS MIXES

Abstract

Bituminous pavements provide a resilient, waterproof, load distributing medium that protects the base course from the detrimental effect of water and the abrasive action of traffic. Bituminous pavements are subject to maintenance due to wear, weathering and deterioration from ageing. Flexibility of bituminous pavement permits slight adjustments in the pavement structure, owing to consolidation of base course or effect of load, without detrimental effect. Hot-mix bituminous pavements are designed by either the Marshall or Gyratory method for normal traffic on roads and streets, using criteria for 100 to 200 psi (7-14 Kg/cm2) tire pressure. Development of modified bituminous materials to improve the overall performance of pavements has been the focus of several research efforts made over the past few decades. Several attempts were made in the past to modify bituminous mixes. The concept of using fibres to improve the behavior of the bituminous mixes is the recent development in the field. This dissertation report compares the effect of polypropylene fibre on bituminous mixes with the help of laboratory investigations. The Marshall stability and flow values have been determined to evaluate the strength and deformation characteristics. To evaluate the field performance, indirect tensile strength, tensile strength ratio, retained stability and permanent deformation have been determined through various tests. It has been observed that Marshall stability values are increasing with in fibre content, density values are decreasing with increase in fibre content and optimum binder content slightly increasing with increase in fibre content. The indirect tensile strength increases with increase in fibre content in mix. Tensile Strength Ratio (TSR) and retained stability have increased with increase in fibre content, indicating improved resistance to moisture resistance. Permanent deformation decreases with increase in fibre content indicating increase in rutting potential.