Performance Evaluation of West Kupang Quarry Rock as Coarse Aggregate in a Class A Aggregate Base Mixture

Abstract

Locally sourced rock can reduce haulage demand in road construction, but a Class A aggregate base must perform as an engineered granular mixture rather than as an unprocessed quarry material. This study evaluates crushed mountain rock from the West Kupang Quarry, East Nusa Tenggara, as the coarse-aggregate component of a Class A aggregate base blended with natural river sand. The laboratory blend comprised 30% 1.5-in crushed rock, 10% 0.75-in crushed rock, and 60% natural sand. Compliance was assessed using combined gradation, Los Angeles abrasion, fractured-particle content, Atterberg limits, fines indices, modified compaction, and soaked California Bearing Ratio (CBR), with the General Specifications of Bina Marga 2018 Revision 2 as the principal criterion. The measured blend remained within the Class A gradation envelope. Abrasion was 22.77%; particles with one or more fractured faces and two or more fractured faces were 96.86% and 91.20%, respectively. The liquid limit was 20.9%, the plasticity index was 4.67%, the PI-times-No.200 value was 11.1, and the No.200/No.40 passing ratio was 0.171. Maximum dry density was 2.068 g/cm³ at 5.66% optimum moisture content, and soaked CBR reached 92.4%. All measured criteria complied with Class A limits. Because the clay-lump/friable-particle result was not documented, final specification acceptance remains conditional on that verification and field quality control.