DETERMINATION OF RESILIENT MODULUS FOR BITUMINOUS MIXES

Abstract

Flexible pavements with bituminous surfacings are widely used in India. The high traffic intensity in terms of commercial over loading of trucks and significant variations in daily and seasonal temperature of the pavement have been responsible for earlier development of distress symptoms. Investigations in India and abroad have revealed that the properties of bitumen and bituminous mixes like Marshall Stability, Resilient Modulus, fatigue life can be improved to meet the basic requirements of pavements by incorporating certain additives or blend of additives and such bitumen which is mixed with any of the additives is called as modified bitumen. Modified bitumens are being extensively explored as it started showing promising results at u very little additional cost involvement. In the present study, an attempt has been made to determine the resilient modulus of the bituminous mixes for both conventional and modified bitumen. Preliminary experimentation was carried out to observe the changes in the basic properties of modified bitumen. Marshall's stability test was carried out to find the optimum bitumen contents for both straight run and modified bituminous mixes at which the resilient modulus test was conducted. Specimens for the conduct of resilient modulus test have been prepared using Marshall's stability moulds. The samples are being extracted and subjected to resilient modulus test for specific number of repetitions. Analytical analysis has also been carried out to determine the resilient modulus for both conventional and modified bituminous concrete mixes. It has been found that the resilient modulus values are high for the modified bituminous mixes when compared with the conventional bituminous mixes which indicates that the load spreading ability and stiffness of the mixes with modified bitumen is more than the conventional mixes, which is desirable in the flexible pavements.