Mechanical and microstructural properties of cemented marine dredged clay with pre-hydrated ground granulated blast furnace slag

Abstract

Marine dredged clay (MDC) is treated with large amounts of cement before being used as construction materials due to its highly water content, leading to a strong demand of economically friendly treatment method. Ground granulated blast furnace slag (GGBS) has been used in concrete production to replace partial cement, but its application in cementing MDC is rarely been investigated. Furthermore, previous studies ignore the self-hydration capacity of GGBS, which may weaken the effectiveness or cause the overuse of GGBS. This study provides a new mixing method (MMII) in treating MDC by pre-hydrating GGBS before mixing with cement, and conducts a series of laboratory tests on the cemented MDC. The influence of GGBS and the mixing method on the mechanical and microscopic properties was examined. The results show that the recommended pre-hydration time is 16 h. The cemented MDC with GGBS obtains higher strength and lower hydraulic conductivity than that of cement-treated MDC with pure cement. Under the influence of MMII, more hydration products are generated due to the two times of hydration, the UCS is improved by up to 20%, the hydraulic conductivity is reduced by up to 17% accordingly. Meanwhile, the size of Ca(OH)2 (CH) decreases to generate calcium silicate hydrate (CSH). By only change mixing order, the engineering performance of cemented MDC with GGBS is improved significantly, showing great engineering benefits and economic values in treating MDC by pre-hydrating GGBS.