Structural Seepage Grouting

Structural seepage grouting (grouting service Mortrench grouting contractors offer) is the sealing off of flowpaths by grouting directly into defects (cracks, joints or open separation) in the floors, walls or roof of an underground structure. Since the work is typically accomplished under flowing water conditions, quick-acting water-reactive urethane grouts are commonly used, though cement- based materials and epoxies may also be utilized.

Structural seepage grouting occurs when there is an outside water source and a flow path from that source into the structure. That flow path may be caused by a crack, joint, or open separation in the below-ground wall of a building, through a void or defect in the concrete building pad, or even through a defect in the waterproofing membrane installed at the time of building construction. Deteriorating underground concrete pipelines are also susceptible to cracking and subsequent water infiltration. The intent of the structural seepage grouting program is to seal off all flow paths by introducing a repair material of sufficient penetrability that it is capable of travel through the flow path, yet must be able to cure to a stable state. Quick-acting water-reactive polyurethane grouts that have an expansion rate of 25-30 times their liquid volume are most commonly used to achieve this objective. Acrylate gels may also be used for applications where lower viscosity is required.

Installation

Structural seepage grouting is generally performed by grouting contractors and crew using water-activated chemical grouts. Prior to the start of the work, locations to be grouted are clearly marked with colored paint. Small diameter (5/8-inch) holes are drilled at 45° angles along the marked areas, typically on 12-18 inch centers, to intersect the cold joint or crack inside the center of the wall. Single-use injection ports are fitted into the drilled holes to allow connection to
the grout pump. Once grouting is completed, the ports are rough-cut flush to the wall face.

Applications

  • Sealing off of water flowpaths in structures below the water table

Advantages

  • Quick-acting water-reactive grouts can be applied under flowing water conditions
  • Non-disruptive grouting techniques
  • Can be applied within low-headroom conditions if required

Limitations

  • Further structural movement and resultant cracking may disrupt previous repairs.

As one of the key grouting contractors, Moretrench’s structural seepage remediation experience is broad. In the immediate aftermath of the attack on the World Trade Center, we were on site using polyurethane grouts to reduce seepage through cracks and dislocated joints in the bathtub diaphragm wall as well as to stop leakage paths through new tieback installations. In Alexandria, VA, we installed a permanent wellpoint dewatering system to alleviate significant groundwater seepage into the underground parking area of a newly constructed building, then urethane and cement-bentonite grouting of the underlying bedding stone was performed to seal flowpaths and fill remaining bedding stone pore spaces. And in Florida, deteriorating concrete box culverts running between the cells of a protected wetland area were remediated with a comprehensive program including cement grouting for settlement control, hydrophobic polyurethane grout for joint sealing, and polymer grout and microfine cement grout to consolidate soils and fill voids and fissures.