Nebraska Local Technical Assistance Program
Nebraska Department of Transportation: Research Reports
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Date of this Version
4-2026
Document Type
Article
Citation
Hu, J., Morcous, G., Aitbayeva, A., and Gerges, M. (2026). "Ultra-High-Performance Concrete (UHPC) for Bridge Deck Overlay and Structural Deck Repair", NDOT Research Report FY24(034).
Abstract
Ultra-high-performance concrete (UHPC) is an advanced cementitious material known for its exceptional strength and durability, making it an ideal material for bridge deck overlays and repairs that address the common issue of premature deck deterioration. Conventional UHPC is typically flowable and self-leveling, which makes it unsuitable for deck surfaces with cross-slopes and/or sloped vertical profiles. Therefore, a highly thixotropic UHPC that responds well to vibration while remaining stable on sloped surfaces is needed for overlay applications. Mixtures with varying binder content, water-to-binder ratio, fiber content, and dosages of admixtures were developed and evaluated. Two of the most effective and economical mixtures were selected for full-scale mockup construction and testing.
Six full-scale sloped slabs were prepared using three surface preparation methods: surface retarder for fresh concrete, fine milling, and typical milling for hardened concrete to simulate field conditions for overlay applications. The structural performance of the composite slabs and the bond between UHPC overlays and concrete substrates were tested to evaluate the effectiveness of each surface preparation method. Flexural tests were conducted under both positive and negative bending, and the experimental results were compared with predictions according to the latest AASHTO UHPC Guide Specifications. The two UHPC mixtures developed in this study were further evaluated for their workability, mechanical, and durability properties. They showed excellent performance compared to the UHPC overlay mixes reported in the literature. The study also confirmed the constructability of the developed mixtures using traditional construction equipment.
Recommended ranges for various workability indicators were proposed based on the performance of the UHPC mixtures included in the study and mockup evaluation. The three surface preparation methods investigated were sufficient to achieve an adequate bond between UHPC overlay and deck slab. Flexural test results of the slabs also demonstrated the significant contribution of UHPC to the flexural capacity of the deck slab in negative-moment regions and the adequacy of the developed prediction models.