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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 13 Abstracts search results
Document:
SP259-07
Date:
February 1, 2009
Author(s):
T.D. Rupnow, V.R. Schaefer, and K. Wang
Publication:
Symposium Papers
Volume:
259
Abstract:
The objective of this study was to evaluate a quick heat generation test to flag changes in cementitious materials in the field. The effects of initial water temperature and initial cement temperature on the quick heat generation curve were evaluated. The effects of different cement chemistries were also studied. Parameters measured include maximum paste temperature at 15 minutes, cement fineness, and cement chemistry. A relationship exists between the both the initial water temperature and the temperature of the paste at 15 minutes and the initial cement temperature and the temperature of the paste at 15 minutes. A linear relationship also exists between the initial paste temperature and the final paste temperature for a single cement source. Laboratory results showed that the quick heat generation test is capable of identifying changes in cement chemistry between different cement sources and the results are reproducible.
DOI:
10.14359/56539
SP259-02
M. Ozawa, S. Uchida, T. Kamada, and H. Morimoto
Drying shrinkage cracking can occur in concrete due to volumetric changes caused by temperature and moisture gradients. The purpose of this study is to acquire fundamental data on the relationship between internal relative humidity and drying shrinkage cracking. The detection of drying shrinkage cracking was performed using the Acoustic Emission method. It was found that the AE measurement technique was successful at detecting drying shrinkage cracking.
10.14359/56534
SP259-01
C. Chung, J.S. Popovics, and L.J. Struble
Ultrasonic wave reflection (UWR) has been used to monitor hydration and strength development of concrete. UWR measures the changes in reflected ultrasonic waves at the interface between a buffer material and hydrating cement paste. To monitor the subtle changes during early hydration it is necessary to use a buffer with low acoustic impedance, close to that of cement paste. In this research, UWR measurements on hydrating Type I portland cement are performed using a high impact polystyrene (HIPS) buffer. Both S-waves and P-waves are analyzed simultaneously to develop and extend the use of UWR to monitor early stiffening of cement paste. The penetration resistance test (ASTM C 403) and temperature rise of cement paste are used to correlate stiffening characteristics. The UWR responses show good correlation with results from temperature rise and penetration resistance. The onset of stiffening is the same for penetration resistance and both P- and S-wave UWR, and nearly the same for temperature rise. It is found that the HIPS buffer can provide sensitive measurement on the early age stiffening of cement paste.
10.14359/56533
SP259-04
A. Darquennes, S. Staquet, A. Kamen, M.-P. Delplancke-Ogletree, and B. Espion
Slag cement concrete is characterized by many advantages, which leads to its intensive use in the construction industry in Belgium. However, it may exhibit a high sensitivity to cracking at early age in case of restrained shrinkage. The understanding of this behavior involves an in-depth analysis of the early age deformations. Firstly, an experimental investigation of the mechanical properties (compression strength, elastic modulus) and the microstructure evolution (hydration kinetic and hydrates development) was performed on three concretes containing different slag proportions (0%, 42% and 71% of the mass of binder), but with identical total binder content, in order to understand the effect of slag on these parameters. Secondly, the autogenous deformations were measured from casting time on concrete cylinders under isothermal conditions. The apparent activation energy and the time of initial set were also evaluated in order to analyse these deformations. The apparent activation energy is used to convert the actual age into equivalent age to express the concrete properties independently of the temperature variations. The time of initial set from which the strains are expressed is determined by ultrasonic detection and by the Kelly-Bryant method.
10.14359/56536
SP259
Editor: Kyle Riding
SP-259CD The American Concrete Institute (ACI) Committee 231, Properties of Concrete at Early Ages, has sponsored a full-day technical session on the Transition from Fluid to Solid: Re-examining the Behavior of Concrete at Early Ages at the ACI Spring Convention, San Antonio, Texas, March 15-19, 2009. This special publication contains the twelve papers presented at this session. The subject matter of these papers includes: (1) the development of concrete properties and microstructure at early ages, (2) test methods for assessing early-age volume change and cracking potential, (3) construction operations timing, (4) computer simulations of early-age behavior, and (5) mechanisms that end the concrete dormant period.
10.14359/56449
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