Enhancement of flexural behaviour of CFRP-strengthened reinforced concrete beams using engineered cementitious composites transition layer

Abstract

This paper aimed to develop and evaluate an efficient strengthening method for reinforced concrete beams, based on engineered cementitious composites (ECC) to be applied as a transition layer prior to the application of the carbon fibrereinforced polymer (CFRP) strengthening sheet. The role of the proposed transition layer is to control the cracking of concrete and detain or even avoid premature de-bonding of the strengthening CFRP sheets. As the ability of the transition layer to exhibit a strain hardening behaviour is mainly dependent on the used fibre volumetric ratio, three ECC mixes with three different polypropylene fibre volumetric ratios were used (fibre volumetric ratio of 0.5%, 1% and 1.5%). The experimental results showed that while the used CFRP strengthening sheet can increase the ultimate load by about 28.8% compared with the control un-strengthened beam, this increase can reach about 48.5% by applying the same CFRP sheet to the proposed ECC transition layer that contains a fibre volumetric ratio of 1.5%. Moreover, this layer integrated with the mention ratio of the fibre content enabled the CFRP sheet to be in a complete contact with the strengthened beam without any de-bonding up the rupture of the CFRP sheet at failure.

Research on Impact Resistance of Reinforced Concrete Beams Strengthened with Carbon Fiber Reinforced Polymer Grid and Engineered Cementitious Composites

“…At present, the use of FRP for reinforcement and strengthening of concrete structures [ 1 , 2 , 3 , 4 , 5 ] is more and more extensive, among the more recent methods are FRP bar strengthened ECC [ 6 , 7 , 8 , 9 ] and FRP sheet strengthened ECC [ 10 , 11 , 12 ], etc. The strengthening methods for RC beams under impact loading are mainly strengthened with FRP sheet/plate [ 13 , 14 , 15 , 16 , 17 ], fiber reinforced concrete [ 18 , 19 ], externally bonded steel plate [ 20 , 21 ], high strength steel wire mesh and high-performance mortar [ 22 , 23 ], etc.…”

Investigation of the Performance of Rc Beams Reinforced With FRP and Ecc Materials

“…When FRP and ECC materials are combined to reinforce a structure, the properties of both can be effectively utilized, and the ultimate load of the structure can be significantly increased. Hence, researchers have used ECC materials as the transition layer to investigate the flexural behaviors of RC beams strengthened with FRP (Afefy et al, 2015;Yuan et al, 2021). The results show that ECC materials could avoid the premature shedding of FRP sheets and improve the ultimate load of the test beams.…”

Impact and static behavior of strain-hardening cementitious composites–strengthened reinforced concrete slabs

“…SHCC materials exhibit tensile hardening behavior accompanied by the formation of fine multiple cracks (Afefy et al, 2016). The application of the SHCC layer as a strengthening material at either tension or compression sides proved its efficiency in enhancing the overall structural behavior under incremental static loading (Afefy et al, 2015; Afefy and Fawzy, 2013; Afefy and Hussein, 2014; Hussein et al, 2012). In addition, it showed a considerable high tensile strain capacity, which is a main important criterion of a durable material to eliminate premature failures (Afefy et al, 2019; Deng and Li, 2006).…”