The influence of fly ash on the bending characteristics of cost-effective cementitious composites

In order to popularize the cost-effective strain hardening cementitious composites (SHCCs) in the tunnel reinforcement, SHCCs were prepared with domestic fibers in this paper. the crack propagation, load-deflection curve, and bending stiffness of SHCCs were studied by using the four points bending test, digital image correlation technology (DIC) and scanning electron microscopy (SEM). The results indicate that all the samples exhibit the characteristics of multi-cracking, and accordingly, the load-deflection curves present the strain hardening behavior. With the content of fly ash ranging from 40% to 60%, the number of cracks, captured by DIC technology, increased from 6 to 12. Meanwhile, the hardening phase of the bending stress-deflection curve became steady along with the flexural strengths dropping from 12.27 MPa to 9.49 MPa. In addition, through fitting the load-deflection curve, there is a good linear rule of stiffness in all the samples during hardening stages, and the stiffness also degenerates linearly with the increase of the fly ash. It is expected that the experimental outcomes are useful to design the target stiffness of cost-effective SHCCs in practical applications. (paper)