Alkali-Activated Ground-Granulated Blast Furnace Slag for Stabilization of Marine Soft Clay

This paper investigated the stabilization efficacy of alkali-activated ground-granulated blast furnace slag (GGBS) for a marine soft clay, compared with that of portland cement (PC). The influence of activators, including NaOH, Na2CO3, carbide slag (CS), NaOH-CS, Na2CO3-CS, and Na2SO4-CS, on the stabilization efficacy was investigated. A range of tests were conducted to investigate the properties of stabilized clays, including unconfined compressive strength (UCS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). The results indicated that Na2CO3-GGBS had no stabilization efficacy for this marine soft clay. NaOH-GGBS-stabilized clay yielded the highest UCS at 7, 28, and 90 days; however, the UCS decreased from 90 to 180 days because of the microcracking. CS-GGBS-stabilized clay had higher 90-day and 180-day UCS than that of PC-stabilized clay, but significantly lower 7-day and 28-day UCS. NaOH, Na2CO3, and Na(2)SO(4)could enhance the strength development rate of CS-GGBS-stabilized clay. However, the UCS of NaOH-CS-GGBS and Na2CO3-CS-GGBS-stabilized clays decreased from 90 to 180 days as well. Na2SO4-CS-GGBS was found to be the optimum binder for this marine soft clay, yielding at least twice higher UCS than that of PC stabilized clay at any age studied. Considerable ettringite was produced in the Na2SO4-CS-GGBS stabilized clay, which contributed to the enhanced strength. (C) 2014 American Society of Civil Engineers.