Date of Graduation

12-2019

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Degree Level

Graduate

Department

Civil Engineering

Advisor/Mentor

Murray, Cameron D.

Committee Member

Heymsfield, Ernest

Second Committee Member

Hale, W. Micah

Keywords

ARDOT; concrete shrinkage; concrete strains; concrete tensile strength; early age cracking; Eurocode equations; transverse cracking

Abstract

The Arkansas Department of Transportation (ARDOT) has identified bridge deck cracking shortly after concrete decks are placed and prior to applying traffic loads. Previous researchers have confirmed improper construction practices and design methods can lead to deck cracking. Currently, many contractors throughout Arkansas are using continuous deck pours. This construction approach may restrict the concrete slab from movement during early age shrinkage, causing tensile stresses to develop. The final stresses at the end of construction must be lower than the concrete tensile strength, if not cracking issues will develop. Eventually, these cracks may enlarge due to service load stresses and environmental damage. A nation-wide Department of Transportation (US DOTs) survey was performed to investigate the early age cracking extensiveness level in other state’s bridges and what corrections, if any, they have made to address this problem. Additionally, Arkansas bridges with early age cracking were visited to examine any trends and inform instrumentation for bridge testing. A bridge deck was instrumented with 32 vibrating wire strain gauges prior to concrete placement to investigate strain and temperature changes in the first 14 days. Eurocode and ACI approximations for concrete mechanical properties were compared to field measured data for improving the understanding of an early age concrete deck behavior in a continuous steel bridge. Stress analysis study through the span length of bridge 030428 detected some locations prone to concrete cracking due to the variability of concrete mechanical properties and stress developed in the concrete deck. This thesis describes the results of this monitoring and anything that can be learned about formation of concrete stresses in continuous concrete bridge deck pours.

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