用水泥和石灰等胶结剂及激发剂构成的固化剂对上海市横沙岛东滩的疏浚土进行改良,在不同养护龄期和固化剂掺量的条件下,用自配固化剂对岛区疏浚土进行了渗透试验。分析了固化疏浚土的渗透系数与固化剂掺量、养护龄期之间的关系, 得到了疏浚土渗透系数在不同固化剂掺入比和龄期下的变化规律。结果表明:固化疏浚土的渗透系数随固化剂掺量和龄期的增加而明显变小,但在同一龄期下,当固化剂掺量继续增加时,其渗透系数变化不大。并利用电镜扫描(SEM)对不同固化剂掺量和不同龄期下的固化疏浚土的微观结构进行观测,获得了疏浚土固化前后的微观结构SEM图,结合SEM图对疏浚土固化前后的微观结构变化做了定性的对比和分析,从固化疏浚土微观结构中发现固化疏浚土中含有水化硅酸钙(C-S-H)、氢氧化钙晶体、无定形文石、钙矾石等能够填充孔隙的胶结物,并从微观上解释了固化剂固化疏浚土的固化机理。

Dredged mud from Hengsha island in Shanghai was improved by curing agent combining exciting agent and bonding agent such as cement and lime. Permeability tests were designed to study the permeability of the improved dredged mud in the presence of different curing ages and curing agent dosages. The relations of permeability coefficient of solidified dredged mud vs. curing agent content and curing time were analyzed, and the law of changes in permeability coefficient was obtained. Furthermore, the microstructure of solidified dredged mud with different curing agent contents and curing ages was observed by Scanning Electron Microscope (SEM) and the SEM images before and after solidification were obtained. According to the SEM images, changes in the microstructure of dredged mud before and after solidification were compared and analyzed. Results show that the permeability coefficient of solidified dredged mud decreased obviously with the increase of curing agent content and curing age; while under the same curing age, permeability coefficient changed little when curing agent content kept increasing. Micro-structure analysis indicates that calcium silicate hydrated (C-S-H), Ca(OH)₂ crystal, CaCO₃ crystal, amorphous aragonite and ettringite which could fill the pores were found in solidified dredged mud. Moreover, the mechanism of solidification of dredged mud was also analyzed from microscopic viewpoint.