Evaluation of Technical Specifications of Gradation Course Base Subdrain Layer Structure on Road

Abstract

Subdrain layer is a type of pavement that can reduce excess water from rainwater so that it can seep into the ground. The purpose of this research is to find the relationship between the optimal water velocity to pass through the base layer and maximum carrying capacity. Sieve analysis was carried out to obtain aggregate gradation variations by modifying the Bina Marga Standards 2010. There are 5 different types of gradations used based on the reduction in the percentage of filler specifications of 8%, 5%, 4%, 3%, and 0%. Calculation of fillers is used to find out the weight of aggregate each sieve size. In addition, the compaction test was carried out on ASTM D Modified 1883 - 87 to obtain optimum water content by using from the maximum dry density curve. The results of compaction the maximum dry density varies with the range 1,911-1,981 gr/cm3. The results of the maximum dry density show that the optimum water content varies between 9-10%. Next, the test sample is reused for CBR testing which aims to determine the carrying capacity of the test sample. Results tend to decrease when the filler is reduced. Obtained CBR test results is in the range of 62-74%. The sample is reused for the infiltration test to find the speed of the water capable of passing the test sample. Based on the results of the infiltration test, the constant infiltration rate varies from 3.143 to 6.750 mm/minute. The constant speed tends to increase when the percentage of filler decreases.