Predicting strength development of concrete by time domain reflectometry

Title: Predicting strength development of concrete by time domain reflectometry
Author(s): Xiong Yu, Vincent P. Drnevich, Jan Olek
Paper category : conference
Book title: International RILEM Symposium on Concrete Science and Engineering: A Tribute to Arnon Bentur
Editor(s): J. Weiss, K. Kovler, J. Marchand, and S. Mindess
Print-ISBN: None
e-ISBN: 2912143926
Publisher: RILEM Publications SARL
Publication year: 2004
Nb references: 25
Language: English

Abstract: Prediction of strength development in concrete is important for construction operation decisions and for the life-cycle performance of concrete structures. Conventional approaches for evaluating the field strength of concrete are destructive, time consuming, and costly. The maturity method shows promise and is being introduced to practice. This paper introduces an alternative approach for predicting the strength development of concrete from electrical conductivity measured by Time Domain Reflectometry (TDR). The rationale for this new approach is that hydration, which directly controls strength development, also induces significant changes in the electrical properties of concrete, which can be accurately and quickly measured by TDR. We found that electrical conductivity of concrete shows a linear decrease with the logarithm of curing time after the initial set. Besides, the electrical conductivity shows strong correlation to the strength of concrete, which is independent of the types of concrete we investigated. This relation indicates that concrete strength can be predicted based on electrical conductivity measurements. Additionally, the long-term strength of concrete can be predicted from short-term TDR measurements. To improve the accuracy of measurement, a temperature compensation factor is established to account for the dependency of electrical conductivity on temperature. The paper describes the testing system, outlines testing procedures, and explains data analysis. The testing system includes a TDR device and a thermocouple, where the device can sample and analyze data automatically. The data are obtained in about one minute. The system uses a disposable probe made from common spikes that can be permanently installed in mass concrete or in concrete cylinders. This new approach has promise for accurate prediction of concrete strength in a fast, economical and non-destructive fashion.

Online publication: 2004-03-25
Classification: Numerical Modeling
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2912143926.030