Summary

The use of very fine cement grouts for injection into fine-to-medium sands has been proposed to circumvent problems associated with the permanence and toxicity of chemical grouts and the inability of ordinary cement grouts to permeate soil formations finer than coarse sand. An experimental investigation was conducted in order to evaluate the penetrability of cement suspensions. Four gradations from CEM II/B-M (according to EN 197-1) type of cement were used having nominal maximum grain sizes of 100μm, 40μm, 20μm and 10μm. The properties of suspensions, with water-to-cement (W/C) ratios of 1:1, 2:1 and 3:1 by weight, were determined in terms of apparent viscosity. Penetrability was evaluated by conducting one-dimensional injections into five different, clean sands using a specially constructed device. Penetrability of cement suspensions increases with increasing cement fineness and water-to-cement (W/C) ratio. In cases of guaranteed injectability of cement suspensions, the use of superplasticizer is not required as it does not affect the result of the injection.

Keywords: Permeation grouting; Suspensions; Microfine cements; Superplasticizer; Sand fraction