Buton Natural Rock Asphalt (BNRA) is the only natural asphalt among severalÂ natural asphalt that stillÂ exist and can be explored in the world.. Â Geological data show that amount 650 million ton of BNRA are found in Buton island. Yet, those amount have not been extensively and maximally used for pavement materials. This paper reported the using of BNRA to modify bitumen to improved the it properties in order resist Â the high temperature rutting, and to stabilized clay soil, toÂ improve their strenght in order suitable to be used as subgrade material. Amount of 15 to 65% of fine BNRA in increments of 5% was added to the bitumen penetration grade 80/100, while amount of 2%, 4%, 6%, and 8% of BRNA by weight of soil were added to the clay soil. Penetration at 25Â°C and softening point test were conducted to the seven mixtures of BNRA-Bitumenâs to determine the penetration index (PI), the parameter of temperature susceptibility of binder. The results show that the BNRA-Bitumenâs binder has low temperature susceptibility. Use as binder in HMA mixtures also shown that the BNRA-Bitumenâs binder can improve the performance of the mixtures. Marshall Stability and stiffness of the mixtures is higher compare to that of base bitumen binder, especially BNRA-Bitumenâs binder with 50% of BNRA, Marshall Stability reach 2374kg and stiffness 311kg.mm, while HMA mixtures with base bitumen (0% BNRA) only has 1294kg of Marshall stability and 169kg/mm of stiffness. For clay soil stabilization, some tests such as Atteberg Limit, California Bearing Ratio, and direct shear were conducted on clay stabilized BNRA. From the study, it was found that BNRA can improve bearing capacity of expansive clay soil better than the natural sand.
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