Title: Effect of surface texture of precast ultra-high-performance concrete tubes on bond strength with normal concrete fill
Date Published: September - October 2026
Volume: 71
Issue: 5
Page Numbers: 37 - 56
Authors: Mina Fakeh and Amir Fam
https://doi.org/10.15554/pcij71.5-02
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Abstract
This study investigated the bond behavior between prefabricated ultra-high-performance concrete (UHPC) tubes and normal-strength concrete (NSC) fill using push-out tests. Bubble-textured and corrugated interfaces were examined and compared with control specimens with a smooth interface. UHPC hoop reinforcement ratio ρc,uh, fiber type, and NSC strength ′ _f c,_n were also varied. The study found that peak bond strength τu ranged from 1.6 to 4.9 MPa (0.23 to 0.71 ksi) for deformed interfaces, compared with 2.0 to 2.3 MPa (0.29 to 0.33 ksi) for smooth interfaces, while residual bond strength τr ranged from 0.0 to 2.0 MPa. Bubbled texture with steel fibers increased τu by 29% to 120%, while corrugations increased τu by 5% to 78%; however, these deformations reduced τr substantially. Medium-sized bubble recesses of 25 mm diameter and 8 mm rise (25 × _8 mm [1.0 × _0.31 in.]) and wavy corrugations of 10 mm pitch and 5 mm amplitude (10 × _5 mm [0.39 × _0.20 in.]) produced the highest τu. The 25 × _8 mm bubbles increased τu by 88%, 112%, and 119% for UHPC ρc,uh of 0%, 0.46%, and 0.93%, respectively, while the 10 × _5 mm corrugations increased τu by 44%, 70%, and 64%, respectively, for similar ρc,uh ratios. POM fibers reduced τu, compared with steel fibers, by 21% to 26% in bubbled interfaces and by 36% to 47% in corrugated interfaces, respectively. Failure of NSC-bubbled protrusions of all sizes and small and medium corrugations was by direct shear, whereas large corrugations slipped over without shearing. Failure was generally accompanied by longitudinal cracking of the UHPC tube, ranging from hairline cracks in small deformations to full splitting and even UHPC reinforcement rupture in large deformations. Empirical models were developed for τu.