Keywords

Deck repair, UHPC, UHPC-NSC Interface

Abstract

The use of ultra-high performance concrete (UHPC) has increased due to its superior mechanical properties and strong bond with normal-strength concrete (NSC). It is widely used as a repair material, particularly in bridge decks, where maintenance remains a challenge. However, the interface between UHPC and NSC is often the weakest region of the composite system and requires careful evaluation.

This study investigates the bond behavior between UHPC and NSC using different surface preparations, test setups, and UHPC materials. The experimental program included unreinforced beams with vertical interfaces tested under three- and four-point flexural loading, and reinforced slabs with horizontal interfaces tested under four-point flexural test.

A total of 169 beam specimens were tested, including two sizes: 102 mm × 102 mm × 356 mm and 152 mm × 152 mm × 508 mm. Two UHPC materials types with different properties were used. In addition, 12 reinforced slab specimens (914 mm × 152 mm × 191 mm).

Four chemical retarders were used to create varying roughness levels: sand finish (SP3), heavy sandblast (SP2), full-depth exposure (SP1), and rake finish (SP4). Surface preparation significantly affected bond strength. UHPC B showed improved bond with more aggressive treatments, while UHPC A performed better with smoother interfaces, indicating that ideal preparation depends on material properties.

Finite element models were developed to further evaluate interface behavior. A NAP model was used for beam specimens, while an OpenSees model was used for slab specimens to capture combined shear and normal effects.

Overall, UHPC material properties and surface preparation strongly influence bond performance. Higher bond strength was generally seen for NSC–UHPC interfaces compared to UHPC–UHPC interfaces. The results highlight the importance of selecting appropriate surface preparation methods to achieve reliable performance in UHPC repair applications.

Completion Date

2026

Semester

Spring

Committee Chair

Mackie, Kevin

Degree

Master of Science in Civil Engineering (M.S.C.E.)

College

College of Engineering and Computer Science

Department

Civil Engineering Department

Document Type

Thesis

Identifier

DP0053304

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