Engineered reclamation fill material created from excavated soft material and granulated blast furnace slag

Due to the rapid development and population growth, many coastal areas and countries are in shortage of land space. Large amount soft soil generated from excavation work has been used as an alternative recently, which is also a challenge because of its poor engineering properties. In this study, ground granulated blast furnace slag (GGBFS), a byproduct of steel industry, was employed to stabilize the excavated soft soil (ESS). Toxicity evaluation shows that the prepared engineering reclamation fill (ERF) materials possessed little impacts on marine ecology. Binder is essential to activate GGBFS. Lime was a better binder than cement. After 7 d curing, the unconfined compressive strength (UCS) of the ERF prepared with GGBFS (24%) and lime (1%) increased up to about 1.5 times of ESS, and the friction angle increased from about 15 degrees to 40 degrees. The addition of GGBFS activated by lime inhibits the swelling of ERF samples and increased the coefficient of consolidation tremendously. After soaking in simulated sea water for 113 d, only ERFs with lime/GGBFS/ESS dry ratios of 1/24/75 and 1/16/83 stood still with UCS of 4718 kPa and 3133 kPa, about 7 and 5 times of ESS, respectively. Scanning electron microscopy images further confirmed the formation of hydration products such as calcium aluminates, calcium silicate hydrates and calcium aluminum silicate hydrates responsible to the enhancement of the ERFs mechanical properties. The prepared ERF sample with GGBFS (24%) and lime (1%) has been proved to be a potential economic and environmental friendly alternative for land reclamation.