Types of Natural Asphalt Mined from Buton Island

Buton Island in Southeast Sulawesi is renowned as Indonesia’s largest producer of natural asphalt. The natural asphalt from this region is popularly known as Asbuton or Buton Asphalt. Asbuton is a natural asphalt material mined directly from rocks containing bitumen. With advancements in road construction technology, Asbuton is now processed into various products with different functions and specifications. The government has recently intensified the use of Asbuton as a raw material for road paving throughout Indonesia. In addition to being part of the downstream processing programme that adds value to asphalt products, the increased use of Asbuton can reduce asphalt imports that drain foreign exchange reserves. According to information from the Indonesian Buton Asphalt Developers Association (Aspabi), there are currently six types of processed Asbuton products circulating in the market. These types of Asbuton have a penetration value of around 5 with a bitumen content of about 20 percent, thus still containing other minerals. In its use, Asbuton B 5/20 is utilised as an additive or supplementary material to improve the quality of asphalt mixtures. This material is processed in an Asphalt Mixing Plant (AMP) with the addition of Pen 60/70 asphalt to produce hot mix asphalt equivalent to modified asphalt. Asbuton B 50/30 originates from the Lawele mine and is also processed into granular particles with specific specifications. Asbuton B 50/30 is used as a substitute for Pen 60/70 asphalt. In the process, this material is mixed with Pen 60/70 asphalt in the AMP to produce hot mix equivalent to the use of conventional Pen 60/70 asphalt. In addition, Asbuton B 50/30 is also used for various other constructions such as Butur Seal, Buton Asphalt Macadam Penetration Layer (LPMA), and Cold-Laid Hot Mix (CPHMA). Pre-mixed Asbuton is Asbuton that has been mixed with Pen 60/70 asphalt at the factory using specific specifications. This product has a purity level of over 90 percent and contains a maximum of 10 percent fine minerals.