GeoSpray® Rehabilitates Heavily Damaged Culvert

GeoSpray geopolymer installation project overview

A culvert running under a busy road needed vital repairs after it was found to be in poor condition experiencing severe corrosion with pitting, and large perforations along the pipe invert. Pipe sections had also started to separate at joints, and the walls were deformed from the external pressure.

The original scope of the rehabilitation project involved the installation of an HDPE liner inserted into the culvert pipe. This option was eliminated due to the curvature and deformed shape of the pipe and ability to fit the required diameter to meet hydraulic requirements. The City of Ottawa arrived at the geopolymer spray on lining option based on cost, speed of installation and reduced traffic disruption after also exploring a CIPP liner.

To carry out the repairs, city engineers awarded the tender to GeoTree Solutions’ installers Gilbert Infrastructure from Saguenay, Quebec to structurally reline the full 64-meter length of the 1800mm corrugated steel culvert under 10 meters of cover with GeoSpray geopolymer mortar.

Culvert repair preparation work included:

• The construction of an access road.
• The placement of a by-pass pumping system to divert flow around the culvert under the roadway to enable the application of the GeoSpray lining.
• The installation of crushed stone and geotextile fabric to create small cofferdams to block flow and prevent geopolymer material spillage at the outlet into the receiving stream.
• Water jet cleaning and removal of large rocks and debris.
• Infiltration sealing with injection grouting.

Additional preparation involved restoring the invert by filling voids with flowable grout. The GeoSpray mortar was than applied using the spin-cast method enabling layers to be added until the required 75mm (3”) thickness was in place. The total repair took just 11 days from start to finish with limited disruption to Timm Drive traffic. The culvert now has an additional 75 years added to its lifespan.