Using ground blast-furnace slag grouts with biopolymer additives for improving sandy soils

The mechanical performance of microfine ground-granulated blast-furnace slag grouts for improving sandy soils was evaluated using unconfined compressive strength, drained triaxial compression and Brazilian tensile strength tests of grouted sand specimens. Two activator types, namely sodium hydroxide and rapid-hardening cement (RHC), and two biopolymer additives, namely xanthan gum (XG) and diutan gum (DG), were investigated for slag-based grouts prepared at various water–binder (w/b) ratios. The bench-scale investigation examined the cured strength properties of grouted sand specimens. It was observed that the RHC activator with modest biopolymer additive and smaller w/b ratio resulted in markedly higher strength gains. In terms of activator type, compared to sodium hydroxide, the RHC resulted in significantly better performance, mobilising increased cohesion in specimens tested in drained triaxial compression. When used together with slag grouts, XG and DG mostly showed comparable strength improvements, but DG proved more effective at lower dosage in increasing tensile strength of grouted sand.