Structural Rehabilitation of a Foundation Wall using Permeation Grouting and Underpinning with Microfine Cement Based Grout, Guelph, Ontario

The excavation of an underground parking and office building led to the rotation and cracking of an old massive, stone masonry foundation wall of a neighboring historic building. Years of gradual deterioration in the stone masonry foundation wall below had reduced this structural wall to a rubble stone wall. When the contractor for the owner of the parking structure excavated below the base of the rubble wall, an injunction and stop work-order was issued and remedial work was ordered. ECO provided expert assistance during the legal action against the Contractor and the Owner of the new structure. ECO in turn was retained to design and supervise a remedial grouting program to structurally rehabilitate the foundation wall using permeation grouting and regular cement based grout in order to allow construction to continue.

The remedial grouting took place in three stages:

1. the foundation wall was shotcreted;
2. the foundation wall was grouted in lifts, using cement grouts, to create a monolith;
3. Through sleeve pipes, the soils below were grouted in multiple passes with microfine cement grouts.

ECO’s experience was particularly required in the last stage, in calculating soil settlement and bearing capacity parameters on which to base the microfine cement injection program. Upon completion of the grouting, supporting braces were removed and the parking complex was completed successfully, with no further impact on the historic building.