Analysis of Cement Addition to Shear Strength of Beach Sand
Liquefaction is a critical geotechnical hazard in sandy soils, particularly in earthquake-prone coastal regions, where loss of effective stress can compromise the stability of foundations and infrastructure. This study investigates the effect of cement addition on the shear strength of Palabuhanratu beach sand through direct shear testing. Sand samples were prepared with cement concentrations of 0%, 15%, and 25% by volume, with a fixed water content of 15%. Physical property tests confirmed poor gradation of the sand (Cu = 2.47, Cc = 0.84), with a dry density of 1.78 g/cm³ and specific gravity of 2.64. Direct shear tests conducted under varying normal loads revealed that the addition of cement significantly increased the shear strength parameters. At 15% cement concentration, the internal friction angle and cohesion improved by 9.11% and 1.88%, respectively, while at 25% concentration, improvements reached 21.26% and 5.00%. These findings demonstrate that cement stabilization enhances the shear resistance of beach sand, offering a simple and effective method to mitigate liquefaction risks in coastal construction projects.