Correlation of modulus elasticity between Light Weight Deflectometer (LWD) and Dynamic Cone Penetrometer (DCP) for subgrade of pavement

Abstract

Pusjatan LWD is an equipment that is purposed to measure the structural strength of a pavement system especially unpaved roads. When the load of LWD falls, it generates vibration recorded by geophones. By using the principles of vibration theory then resulting deflection can be calculated. The deflection value is used for the calculation of modulus elasticity of soil using Boussinesq formula. The LWD is applied to Pusjatan’s yard in Bandung for sample of subgrade, where in each location we have taken ten data using LWD and DCP on the same tested points. The reason of comparing between LWD and DCP is that the former equipment used to measure the subgrade structural strength. The test results are a modulus elasticity then correlated with each other. The test results obtained the determination coefficient r2 = 0.7558, this means that the correlation value is 75.58% determined by the modulus of elasticity value of the DCP measurement, whereas on hard soil the correlation between modulus of elasticity of LWD with DCP Index, with the results r2 = 0.9684 or 96.84%. This indicates a strong correlation. This finding comes to the conclusion that Pusjatan’s LWD can be used to test structural strength of subgrade.