Using IBPs to improve the geotechnical properties of soil

The results of an experimental investigation involving the partial replacement of Portland cement with industrial by-products (IBPs) in grout suitable for suspension-type permeation grouting are described. Four suspension grouts were investigated in this study. Ordinary Portland cement and Portland cement with a 10% partial replacement by bentonite were used as controls. Two grouts containing IBPs were also tested with a 50% partial replacement by pulverised fuel ash (PFA) and ground granulated blastfurnace slag (GGBS). The results of this study clearly demonstrate that the use of IBPs, especially PFA, can enhance both fresh grout properties and the properties of permeated soil. Partial replacements with PFA reduced the apparent viscosity of the grout by an average of 13% compared with replacements with bentonite, while GGBS reduced the apparent viscosity of the grout on average by 25%. Partial replacement with PFA also yielded superior groutability results due to the combination of a lower apparent viscosity and a finer cement gradation compared with replacements with bentonite. Replacement of Portland cement with PFA also improved the grouted properties of the soil, with a decrease in the coefficient of permeability of 20% being obtained compared with replacements with bentonite.