Flexural Behavior of Desert Sand Concrete Beams Using DIC

Desert sand concrete (DSC) cube and beam (DSCB) specimens were prepared to investigate the influence of desert sand from Ningxia, China, on the flexural behavior of concrete beams. Specimens were produced with different desert sand replacement ratios (DSRRs), and the cubic compressive strength (CCS) of DSC cubes were measured. Digital image correlation (DIC) was applied during four-point bending tests to characterize full-field strain distributions and to track crack initiation and propagation. The results indicate that CCS peaked at a DSRR of 25%. This value represented a 6% increase relative to natural sand concrete (NSC). The ultimate flexural capacity of DSCBs reached its maximum at this DSRR. This corresponded to a 2.5% increase relative to a natural sand concrete beam (NSCB). The cracks in DSCBs developed more significantly. Failure mode of DSCBs transformed from ductile to brittle at a DSRR of 50%. The current Chinese code can provide a reference for the engineering design of DSCBs, and appropriate modifications considering the DSRR are recommended for different stress stages. These findings provide a theoretical basis and technical support for the practical application of DSC.