Tdr For Compaction Control Of Granular Materials With Large Particle Sizes

Abstract

Compaction of soil is typically controlled by specifying water content during placement to achieve a desired dry density. Earlier work at Purdue University provided the means of applying Time Domain Reflectometry (TDR) technology to compaction control by relating dielectric constant and bulk electrical conductivity determined from TDR with water content and dry density. With time, modifications and new means of applying the technology have been developed and applied, becoming the basis for an ASTM Standard Method of Test (ASTM D6780-2005). However, presently there has been limited study in the use of TDR for the compaction control of granular materials containing large particle sizes. This paper examines the effects of the large particle sizes on accurately determining water content and dry density with the use of the Purdue TDR Method. Testing consisted of lab calibration and field testing. Aggregates tested included Indiana Aggregate Specification 53 (a densely graded aggregate) and 08 (a uniformly graded aggregate), in both crushed stone and gravel forms. This paper explores the effect of spike insertion and its disturbance to the sample, the effect of large particles on the TDR waveform and the determination of the dielectric constant and bulk electrical conductivity, and lab calibration and field testing considerations for compaction control.