Abstract
Fibre-reinforced geopolymer composites (FRGC) are drawing interest as potential repairing and strengthening materials for concrete elements due to their desirable properties. They are known to have good mechanical bond with the concrete substrate and steel reinforcement, good fire resistance, greater durability in corrosive environments, and lower creep and shrinkage characteristics. However, the main challenge in their practical application is the lack of design standards and the structural performance of FRGC-rehabilitated concrete elements has not been fully investigated. In this paper, the result obtained from an experimental study on the flexural behavior of reinforced concrete (RC) beams jacketed by hybrid FRGC is reported. Six repair and strengthening configurations were adopted in this study including jacketing at the bottom, two and three sides of the beam with at least 25 mm thick FRGC layer. Twelve FRGC-jacketed and two control beams were subjected to four-point bending test to determine their loading performance, cracking response, ductility and energy absorption capacity. In addition, an analytical model was developed to predict the ultimate moment capacity of the jacketed beams. The results showed that FRGC-jacketing technique increased the cracking, yielding and ultimate load of the initial RC beams by up to 167%, 62% and 62% respectively. Among the seven repair and strengthening patterns, the bottom and three-sides jacketing provided less ductile response, nevertheless, it offered a 32% increase on the energy absorption value of the initial RC beam. It also indicated that all jacketed RC beams displayed no sign of overlay delamination up to failure, confirming a bond excellence between the FRGC and concrete substrate. The model predicting the flexural moment capacity of the FRGC jacketed beams compared reasonably with the experimental results with error value of 4–7%.
Highlights
In the past decade, the fundamental properties of fibre-reinforced geopolymer composites (FRGC) had been widely investigated and draws interest as a promising material in the construction industry
The present work investigated the flexural behavior of reinforced concrete (RC) beams repaired and strengthened by hybrid Fibre-reinforced geopolymer composites (FRGC) using different jacketing configurations
Twelve FRGC-jacketed and two control RC beams were subjected to four-point bending test to determine their loading perfor mance, cracking response, ductility and energy absorption capacity
Summary
The fundamental properties of fibre-reinforced geopolymer composites (FRGC) had been widely investigated and draws interest as a promising material in the construction industry. The present study used hybrid fibres as composite reinforcement in the repair and strengthening system as compared to mono-fibre reinforcement adopted in some literatures [12,13,14],[15]. As compared to the studies that are adopting blended geopolymer matrix [12], or cement-fly ash blend matrix [13,14,15] in jacketing RC beam, the present investigation attempted to use a 100% fly ash-based geopolymer matrix. This paper presents the experimental investigation on the flexural behavior of RC beams repaired and strengthened by hybrid FRGC using different jacketing configurations. Hybrid steel and Polyvinyl Alcohol (PVA) fibre reinforced geopolymer composite was used as repairing and strengthening materials. It is expected that the output of this study can be used in the establishment of design standards and guidelines pertaining to the use of FRGC in repairing and strengthening structural concrete elements
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