Variation of Crack Width over Time in Continuously Reinforced Concrete Pavement

Abstract

The primary objective of this paper is to present the findings of field studies that investigated variations in crack widths over time in three continuously reinforced concrete pavement projects in Texas. Also presented are crack width variations through the slab depth. Vibrating wire gauges were installed at three slab depths—top, middle, and bottom—during concrete placement. Transverse cracks were induced at the locations of the gauges, and concrete strains were measured. The ages of the projects varied from 11 months to 2 years, 10 months. Significant variations existed in crack widths along the slab depth. Crack widths were largest at the top and smallest at the bottom. In the test sections of this study, crack widths at the middepth were about three-quarters of those at the top. Crack widths at the top and middepth were a direct function of temperature variations in the concrete at those depths. However, there was a poor correlation between concrete temperatures and crack widths at the bottom. There was clear evidence that moisture variations in concrete have substantial effects on concrete volume changes and crack widths. An immediate decrease in crack widths was observed after rains. Crack widths decreased over time within the time frame of this study. This finding is not consistent with the current theory on crack width variations over time, and further study is currently under way at the University of Texas at Austin to identify the causes. The findings will be reported as they become available.

Get full access to this article

View all access options for this article.

References

ERES Division, ARA, Inc. Appendix LL. NCHRP 1-37: Guide for Mechanistic–Empirical Design of New and Rehabilitated Pavement Structures. Transportation Research Board of the National Academies, Washington, D.C., March 2004.

Suh

Y. C.

, Hankins

, and McCullough

B. F.

Early-Age Behavior of Continuously Reinforced Concrete Pavement and Calibration of the Failure Prediction Model in the CRCP-7 Program. Research Report 1244-3. Center for Transportation Research, University of Texas, Austin, March 1992.

Glisic

, and Simon

Monitoring of Concrete at Very Early Age Using Stiff SOFO Sensor. Cement and Concrete Composites, Vol. 22, 2000, pp. 115–119.

Determining the Coefficient of Thermal Expansion. In Concrete Test Procedures, Texas Department of Transportation, Austin, July 2005, pp. 291–298. ftp://ftp.dot.state.tx.us/pub/txdot-info/gsd/manuals/cnn.pdf. Accessed July 30, 2006.

Wells

S. A.

, Phillips

B. M.

, and Vandenbossche

J. M.

Characterizing Strain Induced by Environmental Loads in Jointed Plain Concrete Pavements: Immediately After Paving and Throughout First Ten Months. In Transportation Research Record: Journal of the Transportation Research Board, No. 1947, Transportation Research Board of the National Academies, Washington, D.C., 2006, pp. 36–48.

Prediction of Creep, Shrinkage and Temperature Effects in Concrete Structures. ACI Manual of Concrete Practice, ACI 209R-92, Part 1. Committee 209, American Concrete Institute, Farmington Hills, Mich., 2004, p. 24.

Wicke

ed. Structural Concrete Text Book, Vol. 1. Updated Knowledge of the CEB–FIP Model Code 1990. Fédération Internationale du Beton, Laussanne, France. 1999, p. 224.