Authors : Noor Dhani, Lawalenna Samang, Tri Harianto and A.R Djamaluddin
Abstract: Soil stabilization has been carried out to increase the mechanical capacity, so that, it is possible to bear the load of a construction. Generally, the stabilization is carried out with ash, cement and lime to trigger a pozzolan reaction that able to enhance the cohesion between the soil grains, thus, increasing the mechanical values of the soil. Buton island in Southeast Sulawesi, Indonesia has a large amount of about 627 million metric tons of asphalt deposit in many forms. In Indonesia, natural asphalt derived from Buton island was called Asbuton (Asphalt Buton). The Asbuton deposit divided into several types. One of the types is overboulder which about 30% of the total deposit of asbuton. Overboulder occurred naturally when limestone reacts with bitumen in the topsoil layer of asbuton itself, making it a waste material which could be used as stabilizer material, due to its lime content with low bitumen content at about below 2%. In this study, the researchers are trying to analyze the behavior of soft soil stabilization using overboulder asbuton with and without activator using a plate bearing model test. The activator used in this study was water glass, polymer and iron oxide. Soil investigation started by obtaining the basic and mechanical properties of the soil, followed by element test using CBR and UCS value to determine the best composition. The value of the free compressive strength and the soil CBR value increases after the addition of overboulder and activation. Based on the result of the tests carried out, the optimum addition of the overboulder was 15%, the UCS value of 3680.23 kNm-2 and the CBR value of 38.22%. The presence of an activator material increases the mechanical index of the soil. According to the test results, the highest bearing capacity value was achieved with a composition of 5% iron oxide and 15% overboulder. The unconfined compressive strength value increased by 113% compared to 15% overboulder-stabilized soil. The value of CBR increased by 165 over 15% overboulder-stabilized soil. Based on the results of the model tests show that the stabilized soil with activation of ferro oxide offers better performance as a subbase layer compared to stabilized soil and gravelly sand. With this result, the overboulder can be used as a substitute material for pavement foundation layers with high CBR values. And by using local content, there are opportunities for technical and financial benefits for future development.
Noor Dhani, Lawalenna Samang, Tri Harianto and A.R Djamaluddin, 2020. Experimental Study on Bearing Capacity of Soft Soil Stabilization using Overboulder Asbuton as Sub-Base Layer. Journal of Engineering and Applied Sciences, 15: 1043-1051.