Strength enhancement of Ca(OH)2 activated ground granulated blast furnace slag-stabilized dredged sediments using Na2CO3

Abstract

<p>The efficiency of alkali-activated ground granulated blast furnace slag in stabilizing dredged sediments with high water contents is suboptimal because the activators become diluted. To improve stabilization efficiency, additives such as nano-CaCO3 are proposed. However, some of the proposed additives may not be practical owing to their high costs. This study experimentally investigates the addition of Na2CO3 for the stabilization of dredged sediment with high water contents (i.e., 100%) using Ca(OH)2-activated slag. Experimental results show the optimal content of Na2CO3 to obtain the highest 28-day unconfined compressive strength of stabilized sediments is 0.2% gravimetrically. Below the optimal content, the strength increases with Na2CO3 content. Above the optimal content, a decrease in strength is observed. By examining the reaction products and microstructure of the stabilized dredged sediments, it is observed that the coupling mechanism of cation exchange and calcite precipitation promotes the development of finer capillary pores, leading to a reduction in interpore connectivity and lower structural heterogeneity of the fine capillary pores. Experimental evidence from this study broadens the practical applications of sustainable soil stabilization using additives.</p>