• Grout is degraded more severely by seawater ions, with higher strength loss than paste • High bleeding, porosity, and pore connectivity in grout accelerate seawater degradation • Bentonite enhances grout consistency but is prone to SO 4 2- attack due to lower strength • GGBS improves SO 4 2- resistance but is sensitive to decalcification by Mg 2+ • Synergistic GGBS-bentonite interaction limits seawater reaction and refines pore Maritime construction extensively uses cementitious grouts to fill voids, seal cracks, and stabilize weak ground. Different from cement paste, grouts require high water content for workability, compromising hardened properties and altering deterioration in seawater. This study investigates the durability of cement grouts incorporating bentonite and ground granulated blastfurnace slag (GGBS) over one-year seawater exposure. Physical appearance, volume, mass, strength, phase composition, pore characteristics and microstructure were assessed, considering the effects of Mg 2+ , SO 4 2- , and Cl - ions. After exposure, pure cement grout showed greater expansion, mass loss, and compressive strength reduction than cement paste. This is attributed to higher bleeding water and lower chemically bound water, increasing total porosity by 2.3 times and permeable pore by 1.8 times. Bentonite improved grout consistency, but increased vulnerability to sulphate attack via expansive ettringite formation due to lower mechanical strength and weaker microstructure. GGBS reduced sulphate-induced deterioration, but remained susceptible to magnesium-induced and chloride-induced degradations; pozzolanic consumption of portlandite lowered buffering against magnesium-induced decalcification, while increased AFm phases promoted Friedel’s salt formation. Nevertheless, grout containing GGBS and bentonite exhibited balanced durability performance in seawater, particularly through improved sulphate resistance. The findings elucidate the deterioration mechanisms and provide guidance for designing durable grouting materials.
Ting et al. (Sun,) studied this question.