Abstract:
Permeation grouting is a ground improvement technique that involves the injection of a grout into the pores of a geologic material to improve the strength and/or reduce the permeability of the material. Permeation grouting can be performed with either solution (often referred to as chemical) or suspension (mainly cementitious) grouts; while cementitious grouts are more cost effective than chemical based grouts, their application can be limited due to their particulate nature. Over the last decade, microfine cement grouts have become a popular alternative over ordinary Portland cement grouts for use in permeation grouting because of their smaller particle sizes which allows for grouting finer soils. Nonetheless, the suspension nature of microfine grouts causes them to be susceptible to filtration, which affects the penetrability of the grouts and uniformity of the delivered treatment. This paper presents an inside look at the changes in the “ delivered” water to cement ratio from permeation grouting tests on soil columns constructed with a poorly graded mortar sand. The soil columns were permeated with four different grout mixes to highlight the impact that the filtration tendency of a cement grout has on the cement distribution along the height of the soil column at the end of permeation. Keywords: Permeation Grouting, Microfine Cement Grout, Filtration, Penetrability