Measurement of Volume Change in Cementitious Materials at Early Ages: Review of Testing Protocols and Interpretation of Results

Discussion

“…Moreover, the measured strain after one day was nearly identical to the strain measured according to the ASTM C 157 test on sealed samples (Sant et al, 2006). It is hoped that studies on early-age volume change will continue to reveal the small, yet crucial, experimental details so that researchers can have a brighter outlook on the agreements or shortcomings of early-age volume change measurements.…”

“…The paper by Bouasker et al (2008) is part of an ongoing discussion on measurement techniques of autogenous strain Jensen, 2005a, b, 2007;Sant et al, 2006). We read this paper with great interest.…”

“…In the case of the corrugated tubes by Jensen and Hansen (1995), whose geometry was slightly different from the one used in Bouasker et al (2008), length changes occurring before set should be divided by a factor 2 . 53 if the deformation is assumed to be isotropic (Sant et al, 2006). However, in Bouasker et al (2008) the length changes of the corrugated moulds appear to have been considered when calculating a linear strain directly even before setting, without applying any correction factor.…”

“…When the authors (Lura and Jensen, 2007;Sant et al, 2006) used this approach to perform a series of volumetric strain, linear strain, and non-contact laser measurements, the results were almost identical after setting. Moreover, the measured strain after one day was nearly identical to the strain measured according to the ASTM C 157 test on sealed samples (Sant et al, 2006).…”

Increased Use of Fly Ash in Hydraulic Cement Concrete (HCC) for Pavement Layers and Transportation Structures

“…In fluid systems (e.g., prior to set), this chemical shrinkage does not cause much concern and the entire system collapses on itself resulting in an externally measured volume change that is equal to the chemical shrinkage. However, after the concrete begins to harden, the structure of the cementitious matrix does not enable the externally measured volume change to be equal to the volume of chemical shrinkage (Sant, Lura, & Weiss, 2006). As a result, vapor filled spaces are created within the matrix and stress begins to develop in the hardening paste (Jensen & Hansen, 2001).…”