Flexural Performance of Composite RC Beams Having an ECC Layer at the Tension Face

Abstract

This paper presents an experimental study on the flexural behavior of composite Reinforced Concrete (RC) beams having a monolithic Engineered Cementitious Composites (ECC) layer at the tension face. Due to the brittle nature of normal concrete, clear cover on the tension side of beam cracks results in spalling and corrosion of reinforcement. The proposed technique overcomes the inherent brittle behavior of normal concrete with the incorporation of ECC on the tension face. This also helps in reducing bond-splitting, cover-spalling, and buckling of reinforcement in RC flexural members. For testing purposes, six full-scale beam specimens (225 mm x 300 mm x 2400 mm) with the same reinforcement were cast and tested. Out of six, two specimens were made of conventional concrete, whereas the remaining four (two each) had an ECC layer of 75mm and 100mm thick at the tension face respectively. Each specimen was installed with three strain gauges (one each at the midspan top & bottom surface of concrete and one midspan rebar on the tension face) and one LVDT at midspan. The samples were then subjected to simple monotonic loading under a third-point bending test as per ASTM C78. The load-displacement, stress-strain and moment-curvature curves were obtained for all the tested specimens. It was found that ECC-strengthened beam samples displayed an increased flexural performance at first crack, yield, and ultimate load-carrying capacity as compared to conventional RC specimens. Whereas a better crack arrest with even distribution of cracks and improvement in ductility was observed for the ECC-strengthened composite beams.

Experimental Study of the Shear Performance of Combined Concrete–ECC Beams without Web Reinforcement

“…The increase within the shear-to-span ratio increases with the increase in the shear-to-span ratio; the average value of the increase in the shear-bearing capacity is 27%, and the amplitude of the cracking load is 25%. As the concrete in the tension zone is replaced by ECC, it increases the tensile and shear properties of the lower part of the beam [ 30 ], which makes up for the defects of the brittle concrete that makes the lower part of the concrete prone to cracking and failure and is beneficial to increasing the overall force performance [ 31 ]. However, because the reinforcement also has excellent tensile properties, a higher ECC thickness is not necessarily better [ 32 , 33 ].…”

Flexural Performance of Repaired RC Beams with Grouting and GFRP Sheet Equipped with Anchors

“…Immediate repairs and reinforcement are crucial for RC beam constructions experiencing spalling problems to prevent structural failure and potential fatalities. The repair process involves utilizing grouting mortar as a repair material and strengthening beam surface with GFRP (Glass Fiber Reinforced Polymer) sheets [7][8][9][10][11]. However, the bond between the existing and new concrete or grouting significantly affects the efficacy of using its mortar as a repair material and GFRP sheets for reinforcement [12][13][14][15].…”