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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 9 Abstracts search results
Document:
108-S56
Date:
September 1, 2011
Author(s):
Qi Cao and Zhongguo John Ma
Publication:
Structural Journal
Volume:
108
Issue:
5
Abstract:
The major cause of cracking in bridge decks, concrete pavements, and slabs-on-ground is restrained shrinkage of concrete. Shrinkage-compensating concrete (SHCC) and fiber-reinforced polymer (FRP) are explored to develop a hybrid slab system as one possible method of eliminating this cracking. To achieve this objective, the behavior of hybrid FRP-SHCC beams was studied in this paper as the first-stage development. The expansion property of SHCC is used to decrease cracks in concrete. A series of coffee can tests were carried out to measure and compare the expansion of SHCC from two candidate materials. The selected SHCC candidate mixture was then optimized to achieve the maximum expansion and a decent concrete strength. The optimized SHCC mixture was used to make FRP-SHCC beams. The expansion was measured through strain gauges on the FRP sheets during curing. Both glass fiber-reinforced polymer (GFRP) sheets and carbon fiber-reinforced polymer (CFRP) sheets were used for comparison. A series of third-point loading experiments were conducted to study the behavior of the proposed hybrid FRP-SHCC beams. The results indicate that the proposed system is promising in terms of its ability to develop a residual prestressing effect. Tests also show that the prestressing effect from the expansion of SHCC increases as the axial stiffness of the FRP reinforcement increases.
DOI:
10.14359/51683216
108-M03
January 1, 2011
Sam Slatnick, Kyle A. Riding, Kevin J. Folliard, Maria C. G. Juenger, and Anton K. Schindler
Materials Journal
1
Autogenous shrinkage, significant primarily in concretes with a low water-cementitious material ratio (w/cm), has received more attention in recent years due to the increasing use of high-performance concretes (HPCs). In this study, autogenous shrinkage was quantified in both unrestrained and restrained concrete. The specimens were sealed and kept at a constant isothermal temperature of 20°C (68°F) to prevent deformation due to temperature change or moisture loss. Various materials were evaluated to compare their effectiveness in reducing autogenous deformation and stress development, including saturated lightweight aggregates, shrinkage-reducing admixtures (SRAs), and a shrinkage-compensating additive (based on calcium sulfoaluminate). The data obtained also provide insight into the mechanisms behind autogenous shrinkage and the resulting stress development in restrained members and quantify the effects of methods used to reduce autogenous shrinkage and the resultant stresses.
10.14359/51664212
107-S71
November 1, 2010
Jim Richardson, Sam Eskildsen, Ben Schiller, and Mike Jones
107
6
This paper describes the monitoring of axial strains and curvatures in the slabs and columns of a flat-plate post-tensioned concrete parking deck. Shrinkage-compensating concrete (SCC) was used for the parking deck in lieu of pour strips to speed up construction. The 59 vibrating-wire strain meters were installed during construction in the spring and summer of 2008 and have hourly recorded strains and temperatures until present. Measured axial strains in the slab clearly show expansion due to the SCC, elastic shortening due to post-tensioning, contraction due to creep and shrinkage, and thermal expansion and contraction due to daily and seasonal temperature variations. Preliminary analyses indicate that the SCC experienced significantly less creep and shrinkage than that predicted by design equations for normal concrete. Visual inspections of the slab revealed essentially no cracks due to slab contraction (caused by creep, shrinkage, and temperature change).
10.14359/51664020
104-M69
November 1, 2007
Michael D. Brown, Cuyler A. Smith, J. Greg Sellers, Kevin J. Folliard, and John E. Breen
104
According to a survey conducted in 1996, respondents in several state departments of transportation indicated that more than 100,000 bridge decks in the U.S. have suffered from early age transverse cracking, a crack pattern that typically arises due to drying shrinkage. Concrete material properties are treated as a means through which to improve the resistance restrained drying shrinkage cracking. Various test methods are discussed as they relate to determining the resistance of a material to shrinkage cracking. Materials-based methods of controlling drying shrinkage are presented. The materials discussed include fibers, shrinkage-compensating concrete, shrinkage-reducing admixtures, and extensible concrete. It was determined in small laboratory specimens, and confirmed in large-scale bridge deck specimens, that several of the alternative mixtures adequately reduced restrained drying-shrinkage cracking.
10.14359/18967
JL78-44
November 1, 1981
B. K. Paul, M. Polivka, and P. K. Mehta
Journal Proceedings
78
Tests were carried out with two types of steel fibers to evaluate their restraining capability in shrinkage-compensating concrete. The effect of the fiber reinforcement on compressive flexural strength and modulus of elasticity was investigated. The results indicate that steel fibers can be successfully used for restraining shrinkage-compensating cement. Inclusion of fibers in concrete improved the compressive and flexural strength of both plain and conventionally reinforced shrinkage-compensating concretes. The differences in the moduh were insignificant for practical purposes. Concrete containing bent fibers showed less restrained expansion and higher flexural strength when compared to concrete with straight fibers.
10.14359/10927
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