Effects of cement content and curing period on geotechnical properties of cement-treated calcareous sands

Abstract

Calcareous sands typically have wider ring grain shapes, more significant intragranular porosity, more complex structure, and lower grain hardness, which can hardly meet the strength requirement for overlying infrastructures in ocean engineering activities. Hence, artificial materials are added to improve their mechanical behavior. Firstly, treated specimens are prepared by incorporating Portland cement into calcareous sand with 5, 7.5, and 10% contents and 3–28 days curing times to investigate the loading resistance. Then, the scanning electronic microscope test is conducted to characterize the microstructure with the hydration reaction process. The Portland cement increases the efficiency of strength enhancement since the gels of hydration products lose plasticity and hardening makes the structure denser and have more muscular strength, resulting in structure interlocking and bonding. Secondly, the triaxial consolidated drained test is performed under the confining pressure 100–400 kPa to analyze the mechanical behavior, volumetric behavior, and strength parameters. After the post-yield point, the treated specimens exhibited higher dilation, strain hardening at high cement content. In addition, maximum principal stress ratio, secant modulus, stress ratio, and cohesion increased with curing time and cement content. Moreover, an attempt is made to explain the mechanism of treated specimen strength with hydration reactions.