A LABORATORY STUDY ON ACID MODIFIED BITUMINOUS MIXES IN COMPARISON FOR RUTTING CHARACTERISTICS

The rapid growth in trafficload intensity, tire pressure and traffic volume has put a hugedemand on pavements to perform satisfactorily for the design period. A number of efforts are made in the past to develop pavement materials that helped in attaining longer serviceability. Most of these efforts were directed towards improving the design of bituminous mix through modified bituminous binders. In this context an attempt is made to evaluate rutting characteristics of conventional bitumen modified with Poly phosphoric Acid (PPA). Immersion Type Wheel Rutting Machine was used for evaluation of rutting characteristics and is considered as one of the major critical criteria for design of pavement. Poly phosphoric Acid (PPA) is added as modifier to virgin bitumen (VG – 30) at regular interval of 1% up to 6% to the weight of Bitumen. Bituminous Concrete of Grade-II is considered for Analysis. Slabs of 400X300X50mm are prepared for evaluation of rutting characteristics. Stability, density, voids and flow parameters were determined using marshal test method for virgin and PPA modified mix. The result of immersion wheel rutting explains that acid modified binders resist more rutting compared to virgin binders. Acid modified mixes at 3% optimum performs better in rutting characteristics when tested in laboratory for induced applied pressures, load and number of passes.