Study on Characteristics of Controlled Low Strength Material Using Time Domain Reflectometry

Abstract

The hydration process of Controlled Low Strength Material (CLSM) used for backfill is the primary factor to determine the construction period. The objective of this study is to monitor the hydration process of CLSM using the Time Domain Reflectometry (TDR) and to establish the relationship between dielectric constant and compressive strength. The CLSM specimen is composed of cement, flyash, silt, sand, accelerator, and water. The material characteristics of the CLSM including flow, unit weight, compressive strength are investigated. To measure the dielectric constant of the CLSM during the curing time, TDR probe incorporated with a mold and a reflectometer are used. Experimental results show that the dielectric constant remains constant at early stage, and then decreases as the curing time increases. In addition, the dielectric constant is related to the compressive strength in inverse power function. This paper suggests that the TDR technique may be used as a non-destructive testing method in order to estimate the compressive strength of the CLSM mixture under construction.

Effect of Fly Ash on Strength and Stiffness Characteristics of Controlled Low-Strength Material in Shear Wave Monitoring

“…Various testing methods for evaluating the engineering properties of CLSM have been studied [11][12][13][14][15]. Han et al [11] investigated the relationship between the unconfined compressive strength (UCS) of CLSM and compressional wave velocity estimated from using ultrasonic transducers.…”

“…Byun et al [13] focused on the characterization of the early age properties of CLSM based on piezo disk element and bender element and reported the consideration on the geometric boundary condition of the container in wave characterization. The hydration process of CLSM was also monitored using time-domain reflectometry, and the relationship between the dielectric constant and UCS was suggested [14]. Furthermore, direct shear tests of CLSM and soils were performed to evaluate the interface friction between CLSM and natural soils that could be around the trenches filled with CLSM in the field [15].…”