Application of a self-compacting ultra-high-performance fibre-reinforced concrete to retrofit RC beams subjected to repeated loading

Abstract

The aim of this paper is to describe the performance of reinforced concrete (RC) beams retrofitted with a self-compacting ultra-high-performance fibre-reinforced concrete (UHPFRC) under three-point bend cyclic loading. It is found that retrofitting the RC beams with a thin UHPFRC strip on the tension face increases their endurance limit under a non-zero mean stress cyclic loading from approximately 40% to approximately 60% of their static three-point flexural strength. Moreover, the retrofitted beams behave as a composite structure, with no delamination of the retrofit strip being observed in any of the fatigue tests.

Amelioration of Flexural Performance for Reinforced Concrete Beams by Soffit Bonded High Performance Self Compacting Concrete Prisms

“…An angle grinder was used to repair the concrete surfaces by creating a grid of 45º inclined straight-line grooves of 2 mm depth which were spaced 50 mm apart. As mentioned by Al-Azzawi [28], for all beams and strips as shown in Fig. 7.…”

“…The strip was then stacked on the beam with uniform pressure. To guarantee efficient adhesion, pressure was applied by setting G-clamps until the adhesive hardening for at least 24 hours [28], as shown in Fig. 8.…”

Experimental Research on Fatigue Behavior of Reinforced UHPC-NC Composite Beams under Cyclic Loading

“…In the case of UHPC-NC composite beams being monotonically loaded in bending, the experimental conclusions reported in previous studies have shown that the bond performance between UHPC and NC layers is likely to be affected by UHPC layer thickness [40,41]. Further analysis of the interface performance of the UHPC-NC composite beams under cyclic loading was discussed in detail below.…”

“…The adopted maximum loads varied between 40% and 60% of the ultimate capacity of the beam; an obvious reduction in macrocracks for the composite beams was observed during bending fatigue tests. Al-Azzawi [41] conducted fatigue tests on RC beams strengthened with the unreinforced UHPC layer in three different load ranges, i.e., 3.5-46.9%, 3.5-61.0%, and 3.5-82.1% of the static load-carrying capacity. Although only one of the beams was loaded to failure, the results indicated that fatigue resistance was increased and the fatigue life was prolonged for the strengthened beams relative to the corresponding un-strengthened control beams.…”