Improvements in lightweight concrete T beams CFRP strengthened and anchored with U-wraps

This research provides a study for an experimental program using sand-perlite-lightweight reinforced concrete (RC) beams strengthened and anchored with carbon fiber reinforced polymer (CFRP) materials. The main objective of this work is to showcase the efficiency of using U-wrap anchors to secure the externally applied CFRP sheets on lightweight RC beams. A series of six full-scale T-beams with an increasing number of CFRP U-wraps per shear span was prepared and tested. The use of U-wrap anchorage enhanced the flexural performance of the sand-lightweight concrete beams by progressively delaying the premature debonding of CFRP sheets as a direct function of the number of U-wraps used per shear span. The beam flexural capacity gradually improved from 116 kN without the use of U-wrap anchors to 182 kN when using six U-wraps per shear span, which reflects a significant enhancement. Similarly, the ultimate deflection gradually improved from 56 mm for the beam without U-wrap anchors to 94 mm when applying six U-wraps per shear span. A design model established earlier, for normal weight concrete, has been successfully qualified to yield accurate findings against the experimental results. Also, the outcome of this study interestingly showed that the ultimate strength results of the anchored beams were close to their counterparts of normal weight concrete conducted on identical beams. This finding shows that U-wrap anchors performed efficiently despite the lack of coarse aggregate interlock in the concrete mix.