Modified Testing Device to Evaluate MR Properties on Fly Ash Treated Subgrade Soil
The need to obtain reliable resilient modulus (MR) for fly ash treated subgrade soil in pavement thickness design in Taiwan prompted the modification of the existing standard testing device. In the modified device, a load cell and two linear variable differential transformers (LVDTs), conforming to TAI and AASHTO methods, were used to measure the axial load and deformation of specimen. To control the testing and data acquisition process, a computer program for MR of fly ash treated subgrade soil, “MRSS,” was developed using a 14-bit A/D convertor for data processing. The software is capable of simulating various testing conditions, such as load duration, varying repeated loads, and cycle duration. For monitoring purposes, the software is written to plot the stress-time and deformation-time curves, which were found to resemble the shape of a haversine curve. Through the calibration procedure, the performance of this modified testing device was found to be reliable and accurate.