Experimental and theoretical study on flexural behavior of Normal Concrete-Engineered Cementitious Composites (NC-ECC) laminated functionally graded beams

To effectively avoid the inherent limitations of conventional beams and laminated beams, the functionally graded material theory was applied to composite beams, thereby establishing the laminated functionally graded beam theory. Considering the influence of the number of functionally graded layers (i.e., two, three, four layers), functionally graded design (i.e., linear design, theoretical design), and reinforcement ratios (i.e., 0.73 %, 1.05 %), a total of 12 beams were designed and tested, consisting of 2 NC beams, 2 ECC beams and 8 NC-ECC laminated functionally graded beams. The mechanical properties of each sublayer of laminated functionally graded beams were investigated by uniaxial compression and uniaxial tension tests. The flexural behavior of the laminated functionally graded beams was investigated through four-point bending experiments. The experimental results showed that NC-ECC laminated functionally graded beams exhibited significantly more cracks than ECC beams, but no significant crack width reduction was observed. Compared with the NC beam, the average crack width of the NC-ECC laminated functionally graded beam decreased by 80–95 %, and the maximum crack width decreased by 50–80 %. With the number of functionally graded layers increased, the number of cracks increased, crack width decreased, crack distribution became more uniform, and the bending performance of laminated functionally graded beams gradually improved. • The model for laminated functionally graded beams was developed and validated. • Laminated functionally graded beams can significantly reduce crack width. • With the increase in sublayers, the bending performance has gradually improved. • Increasing sublayers and reinforcement ratio can mitigate interlayer cracks.