Research on the Fracture Behavior of Ultra-fine Dredged Sand Concrete Based on the Microstructure Characteristics

The dredged sand generated by the dredging projects has been abandoned and reclaimed from designated areas. It meets the requirements of environmental construction and resource utilization, if the dredging sand can be used as building material in construction. In order to investigate the fracture behavior of dredged sand concrete, five kinds of concrete with different dredged sand replacements (0 %, 12.5 %, 25 %, 37.5 %, 50 %) were designed in this article. Three-point bending fracture tests were carried out on the concrete. The test results show that with the increase of dredged sand replacement, the initiation load, peak load, fracture toughness, and fracture energy first decrease and then increase. Computerized tomography scan and mercury intrusion porosimetry tests show that with the increase of dredged sand replacements, the porosity, pore volume, and pore surface area increase first and then decrease. Dredged sand can improve the pore structure, increase the compactness of concrete, and improve the fracture behavior of concrete. Scanning electron microscopy and X-ray diffraction tests show that dredged sand mainly plays the role of physical filling, and proper dredged sand can improve the compactness of concrete.