不同水泥掺量大湾区淤泥加固土性能变化规律及微观分析

Performance and Microscopic Analysis of the Greater Bay Area Organic Soils Treated with Different Cement Ratios

为了深入了解不同掺量水泥对广东大湾区淤泥的加固效果,掺入不同比例P.O 42.5水泥,制作了淤泥固化土试块。进行了1、3、7、14、28 d标准养护下的SEM分析及XRD分析。结果表明,在1~7 d时,水泥掺量为8%和10%的固化土试样水化产物含量差别不大,均有明显的针棒状物AFt产生。养护28 d时,10%水泥掺量的固化土水化产物C-S-H明显增多。结合工地现场的钻孔抽芯和静载检测结果,28 d龄期后10%水泥掺量固化效果更好,虽然水泥掺量仅增加了2%,但是强度和地基承载力分别提高了32.6%和54.6%,说明水泥固化淤泥的效果存在掺量下限阈值。研究结果对采用水泥固化淤泥工程实践有一定的参考价值。

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 quanti-tative 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 con-tent of hydration products in the improved soil samples with cement content of 8%and 10%has little difference.There are ob-vious 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 1o%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 re-sults have some reference values for the practical application of cement improved organic silty soils in the Greater Bay Area.