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|Title:||A low-modulus internal concrete strain meter|
|Authors:||United States. Assistant Secretary of the Army (R & D).|
Alexander, A. Michel.
|Keywords:||Strain meters (concrete)|
Strain measuring instruments
|Publisher:||Concrete Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; C-74-9.|
Abstract: Previous work has indicated the need for a low-modulus internal strain meter to define better the behavior of fresh portland-cement concrete. Such a meter was designed and constructed, using the linear variable differential transformer (LVDT). It and two well-known commercially available strain meters were tested for comparison purposes. The LVDT meter was found to be capable of measuring volume changes in fresh concrete as well as in hardened concrete. Currently available meters are designed to measure strains only in hardened concrete. After the concrete had attained final set, all three of the meters tested gave volume change results that were essentially comparable. The LVDT meter is recommended to be used for short-term strain measurements in concrete. It is also recommended that further work be performed to fully prove out the meter in long-term use in concrete. It would be advantageous to construct meter having temperature correction equal to the linear coefficient of thermal expansion of concrete or even a zero temperature correction. It would also be advantageous to construct a meter with an axial length of 1 in. or less.
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