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Open AccessArticle

A New Non-Destructive TDR System Combined with a Piezoelectric Stack for Measuring Properties of Geomaterials

1
High Speed Railway Research Division, Korea Railroad Research Institute, 176, Cheoldobangmulgwan-ro, Uiwang-si, Gyeonggi-do 437-757, Korea
2
Department of Civil Engineering, College of Engineering, Chosun University, 375 Seosuk-dong, Dong-gu, Gwangju 501-759, Korea
3
Department of Civil Engineering, College of Engineering, Case West Reserve University, Cleveland, OH 44106, USA
*
Author to whom correspondence should be addressed.
Academic Editor: Jorge de Brito
Materials 2016, 9(6), 439; https://doi.org/10.3390/ma9060439
Received: 29 February 2016 / Revised: 12 May 2016 / Accepted: 27 May 2016 / Published: 2 June 2016
Dry density and water content are two important factors affecting the degree of soil compaction. Conventional methods such as the sand cone test and the plate load test are used to measure such properties for evaluating the degree of compaction and the stiffness of soil in the field. However, these tests are generally very time-consuming and are inherent with some errors depending on the operator (in particular for the sand cone test). Elastic modulus is an indicator to describe the stress-strain behavior of soil and in some cases is used as a design input parameter. Although a rod type TDR (Time Domain Reflectometry) system has been recently proposed to overcome some shortcomings of the conventional methods (particularly the sand cone test), it requires driving the probes into the ground, thus implying that it is still a time-consuming and destructive testing method. This study aims to develop a new non-destructive TDR system that can rapidly measure the dry density, water content, and elastic modulus of soil on the surface of compacted soil, without disturbing the ground. In this study, the Piezoelectric Stack, which is an instrument for measuring the elastic modulus of soil, has been added to the TDR system with a flat type probe, leading to a non-destructive TDR system that is capable of measuring the dry density, water content, and elastic modulus of soil. The new TDR system developed is light enough for an engineer to carry. Results of the standard compaction and TDR tests on sand showed that the dry densities and the moisture contents measured with the new TDR system were in good agreement with those measured with the standard compaction test, respectively. Consequently, it appears that the new TDR system developed will be very useful to advance the current practice of compaction quality control. View Full-Text
Keywords: TDR; dry density; water content; elastic modulus; soil; compaction TDR; dry density; water content; elastic modulus; soil; compaction
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MDPI and ACS Style

Choi, C.; Song, M.; Kim, D.; Yu, X. A New Non-Destructive TDR System Combined with a Piezoelectric Stack for Measuring Properties of Geomaterials. Materials 2016, 9, 439.

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