Feasibility Analysis of Timor Island Mountain Rock as Selected Fill Material for Road Construction: West Kupang Quarry

Abstract

The use of locally available materials can reduce material-mobilization constraints in road construction, but their engineering suitability must be established through laboratory evaluation. This study evaluates mountain rock from the West Kupang Quarry, Timor Island, as selected fill for road construction using available physical and mechanical test data and the General Specifications of Bina Marga 2018 Revision 2 as the technical reference. A laboratory experimental method with a descriptive-quantitative approach was applied. The tests included specific gravity and water absorption, compaction, and soaked California Bearing Ratio (CBR). The material showed a bulk specific gravity of 2.559, SSD specific gravity of 2.601, apparent specific gravity of 2.669, and average water absorption of 1.658%. The maximum dry density was 1.881 g/cm³ at an optimum moisture content of 6.29%. The CBR reached 39.14%, exceeding the referenced minimum value of 10% for selected fill. These results indicate favorable density and bearing-capacity characteristics and support the potential use of the material in road earthworks. Nevertheless, gradation and plasticity data were not available in the evaluated laboratory dataset; therefore, additional testing is required before complete compliance and final field acceptance can be confirmed.