Engineering properties of bituminous mixture using kaolin as a modifier

Abstract

The pavement system plays an important role in the economic and social sectors of a country. Construction of pavement is increasing day by day to cater for the huge traffic volume. Subsequently, it is important to improve the quality of road structure to reduce congestion and disruptions of journeys for road users. Improvements of road pavement using conventional bitumen are inadequate to prevent pavement deterioration. Research has been done on modification of bitumen to address this problem. In this research, kaolin was used for the modification of bitumen to improve the quality of roads. Kaolin was added at an increment of 2%, starting with 0% to 12% by weight of bitumen of PEN 80-90 and 80-100 to analyse the physical and rheological properties of the modified bitumen. Short term aging and long term aging were carried out on the modified bitumen to simulate the condition of aging during production, and after laying of bituminous mixture on roads. Penetration and softening point tests were performed to determine the physical properties. Penetration index was calculated from penetration and softening point tests, which indicated the temperature susceptibility of the modified bitumen. Viscosity and Dynamic Shear Rheometer (DSR) tests were carried out to determine the rheological properties of this bitumen. Complex shear modulus (G*) and phase angle (d) are the two parameters of DSR. A Marshall test was carried out on the bituminous mixture which was prepared from kaolin modified bitumen PEN 80-100. The engineering properties of the modified bitumen indicated that their physical and rheological properties have improved. The significant effect was that, kaolin reduced penetration depth and increased viscosity of modified bitumen. The modified bitumen has shown better elastic response and stiffness, which indicate a strong correlation of rutting resistance associated with temperature. A higher percentage of kaolin modified bitumen has been shown to be very close to failure criteria of fatigue cracking due to hardness of modified bitumen. Marshall properties of kaolin modified bituminous mixture has a higher stability and lesser deformation. It can be concluded that kaolin modified bitumen improves quality of road pavements where the temperature is high.