Abstract: To gain an in-depth understanding of the improvement effect of different amounts of cement ratios in the organic silty soils in the Guangdong Greater Bay Area, different ratios of P.O 42.5 cement were added to in the soil samples for the quantitative evaluations. The Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) analyses on samples under the standard curing ages of 1, 3, 7, 14 and 28 days were performed. The results show that, curing ages from 1 to 7 days, the content of hydration products in the improved soil samples with cement content of 8% and 10% has little difference. There are obvious needle-like Hydrate Ettringite (Aft) formation. When curing for 28 days, the hydration products calcium-silicate-hydrate (C-S-H) of the improved soil with 10% cement content increased significantly. Combined with the results of coring samples and static load testing at the construction site, the curing effect of 10% cement content after a curing age of 28 days is better. Although the cement content only increases by 2%, the strength and foundation bearing capacity are increased by 32.6% and 54.6%, respectively, which indicating that there is a low threshold for the effect of the cement improved organic soils. The results have some reference values for the practical application of cement improved organic silty soils in the Greater Bay Area.

Key words: SEM, XRD, Improvement of Organic Silty Soils, Microscopic Analysis, Foundation Bearing Capacity Testing