Utilization of Non Destructive Test for Mix Design and Process Control of Cement-Treated Base Layers

Abstract: This research delves into the use of Non-Destructive Testing (NDT) to assess the unconfined compressive strength of Cement Treated Base (CTB) material during the mix design and quality control phase. CTB specimens were cast using three cement dosages under optimal moisture and density conditions. These specimens were then cured in a sand bath for up to 28 days. The 7-day and 28-day unconfined compressive strength was measured using a traditional compression testing machine and a rebound hammer for all cement dosages. Statistical methods were employed to establish the relationship between the compressive strength measured using both destructive and non-destructive methods results over the 7 and 28-day curing periods. Using a rebound hammer showed promise in estimating the compressive strength of CTB materials. Additionally, NDT offered insights into the consistency of mixing and compaction achieved in each specimen during laboratory fabrication and field compaction. The established relationships were validated with specimens of varying geometrical shapes, such as cubes and cylinders. The research indicates that the rebound hammer technique could be used for routine process control and confirmatory testing once used during mix design to establish target rebound values of the hammer. The proposed framework and relationships developed between NDT and conventional test results are expected to aid engineers in reducing testing and minimising damage to pavement structures during process control.