Technical Paper ISSN 1997-1400 Int. J. Pavement Res. Technol. 7(1):25-30 Copyright @ Chinese Society of Pavement Engineering Vol.7 No.1 Jan. 2014 International Journal of Pavement Research and Technology 25 Comparing the Performance of Granular and Extracted Binder from Buton Rock Asphalt Kemas Ahmad Zamhari 1+ , Madi Hermadi 2 , and Mohamed H. Ali 2 ─────────────────────────────────────────────────────── Abstract: Buton Rock Asphalt (BRA) is natural rock asphalt found in Buton Island, Northwest Sulawesi, Indonesia. This study compares the performance of asphalt concrete made by two different methods of BRA binder preparation. The first method heats and crushes the rock into granular asphalt, while the second method extracts and recovers the bitumen out of the rock to produce pure BRA bitumen. Petroleum bitumen is used as a control. Rheological properties of pure BRA bitumen, a blend of petroleum bitumen, and pure BRA bitumen were determined. The properties of these binders were used to quantify the contribution of binder in resisting permanent deformation and fatigue cracking. Bituminous mixtures of different BRA binders and petroleum bitumen were prepared. Ordinary bitumen was added to the mixture of granular BRA to achieve the optimum bitumen content. It was found that BRA binders yield mixtures with better stiffness modulus, rate of permanent deformation, and creep stiffness compared to petroleum bitumen mixture. Mixtures with a higher percentage of granular BRA yield a better performance when compared to the mixture of pure BRA bitumen. It may be concluded that granular BRA would be the best alternative, provided that the transportation cost of the material from Buton Island can be competitive. DOI:10.6135/ijprt.org.tw/2014.7(1).25 Key words: Buton rock asphalt; Creep stiffness; Extracted binder; Granular asphalt; Stiffness modulus. ─────────────────────────────────────────────────────── Introduction 12 Buton Rock Asphalt (BRA) is natural rock asphalt from Buton Island, Northwest Sulawesi, Indonesia. Basically, BRA is bitumen impregnated limestone. Consistency of its bitumen varies from low to high penetration grades. The deposits are located in different places along the island. The biggest deposit was found in the Lawele Region. Total BRA deposits on the island are estimated at 677,247,000 tons, while the Lawele region alone contains around 210,283,000 tons [1]. At present, the transportation cost as well as the purification cost of the BRA bitumen restrained the utilization of BRA mostly to the area close to the island. However, efforts to improve the technology of producing BRA as an asphalt binder of high quality are continuously evolving. It is believed that with such a large reserve of natural asphalt and steadily increasing crude oil price, BRA is an attractive alternative source of bituminous binder of the future. Two different methods of BRA binder preparation can be applied. The first method involves heating and crushing the BRA to decrease its water and volatile oil content and to reduce the size of granular rock asphalt to 9.5 mm maximum size. The second method involves extracting and recovering the bitumen out of the rock to produce pure bitumen. The granular BRA is easier to produce; hence, the production cost is relatively low. However, because its mineral content is high, the handling and application are comparatively more difficult than normal hot mix asphalt. Transportation cost is 1 Research Centre for Soft Soil Malaysia. 2 Faculty of Civil and Environmental Engineering, University Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor, Malaysia. + Corresponding Author: E-mail kemas@uthm.edu.my Note: Submitted October 18, 2012; Revised July 12, 2013; Accepted July 14, 2013. critical for granular BRA, especially if the bitumen content is low. Only BRA, which contained more than 20 percent of bitumen is currently considered as commercially viable. Pure BRA bitumen is identical to petroleum bitumen; therefore, its application and handling is similar to that of the ordinary bitumen. Nevertheless, the high bitumen extraction and recovery costs may cause this product to be less competitive at present. This study compares the performance of asphalt concrete made by the two different methods of BRA binder preparation, namely granular BRA and pure BRA bitumen. BRA from the Lawele region is used; it contains 70-80% mineral, 20-30% bitumen, and 2-10% water. The bitumen has an initial penetration value around 180 dmm and contains around 7% volatile oil. Penetration grade 80/100 petroleum bitumen is used as a control. Materials and Methods Materials used in this study are petroleum bitumen penetration grade 80/100, a raw BRA, and aggregate. Flowchart of the laboratory tests performed is shown in Fig. 1. The raw BRA was processed to produce both granular BRA and pure bitumen of BRA. The characteristics of the petroleum bitumen, granular BRA, and pure BRA bitumen are exhibited in Tables 1 to 3, respectively. Table 2 indicates that raw BRA has high water and volatile oil contents, flash point close to mixing temperature of hot mix asphalt, and high penetration, which means it is too soft, especially for the tropical climate where bitumen with penetration grade 60/70 or 80/100 are normally preferred. In order to use BRA as an asphaltic binder that is suitable for hot mix asphalt, the raw material was heated until 120-130 o C to reduce water and volatile oil contents. In addition, the heating processes loosened the internal bonding of lumped raw BRA and crumbled the lumps into the size of fine to medium aggregate fractions with the