Deck Reinforcement Detailing and Concrete Mix Additives to Reduce Bridge Deck Cracking

Project summary:

Bridge decks are costly and difficult elements to maintain, and the presence of deck cracking may hasten deterioration of the structures. Despite recent changes to Minnesota Department of Transportation (MnDOT) mix designs, transverse cracking has still been observed shortly after the bridge deck is poured. The goal of this project is to determine the causes of this cracking and to propose deck reinforcement or mix design practices that efficiently mitigate the problem. Research efforts will focus on modeling bridge deck thermal and time-dependent stresses using the finite-element method, with material testing supporting the analysis. Computational parametric studies will be employed to examine the efficacy of changing longitudinal bar spacing, controlling girder and deck temperatures during a pour, reducing shrinkage strains, and other such measures. Material testing will be conducted to determine the relevant material inputs for the model and to demonstrate how changes to mix design may achieve reduced deck cracking.

The main objectives of this research program are to:

1. Determine the causes and magnitudes of tensile stresses within bridge decks for concrete slab-on-girder systems.

2. Quantify the crack control benefits of altering deck reinforcement details or mix designs.

3. Propose design criteria, deck details, deck pour procedures, or mix design changes that may efficiently alleviate bridge deck cracking.