Culvert rehabilitation is becoming increasingly important. Many aging culverts across the US, and internationally, have deteriorated to the point where replacement or repairs is necessary. A determination must be made regarding structural integrity of the host pipe before deciding whether to replace or rehabilitate.
In many cases, it is typically more cost-effective and efficient to repair and rehabilitate an existing culvert. Many rehabilitation methods exist, each with their own advantages and disadvantages. Each individual culvert rehabilitation project is unique and should be carefully analyzed before deciding which method is right for the each, specific project.
Trenchless Culvert Rehabilitations Methods:
For the slip lining method, rigid liner pipes are pushed or pulled with jacks or inserted using construction machinery, into the existing pipe. Once the liner is placed, the annular space (space between new and old culvert), must be grouted to fill the space and seal the rehabilitated pipe.
Spiral Wound Lining
To form a smooth and continuous spirally wound liner, interlocking profile strips are coiled through the existing pipe using a winding machine that forces the strips to interlock. There are three different ways this can be done, depending on the individual culvert project. The Spiral wound pipe can either be inserted at a fixed diameter and then expanded until it presses against old pipe, inserted at fixed diameter and then grouted, or wound against the original pipe by a machine that travels down the pipe.
The process of installing a cured-in-place pipe lining involves inserting a flexible fiber tube coated with a thermosetting resin into an existing pipe by either pull-in-place or inverted installation. regardless which installation method is chosen, the next step is to activate the chosen resin with heat.
After the application of heat to the resin, it becomes the primary structural component of the cured-in-place system, forming a jointless pipe within a pipe. After the culvert is cured, cutters are used to reinstate laterals and junctions.
This method of culvert rehabilitation uses coiled PVC pipe liner on reels, at project-specific lengths. Depending on the diameter of the pipe, the liner comes in a flat shape or an “H” shape.
Ultimately, the PVC liner is heated twice throughout the installation process. Before installation, the liner is heated until the liner becomes malleable for use.
Once the liner is pulled through the existing culvert, it is sealed on both ends where steam and compressed air heat, expand, and cool the new lining. This process causes the new lining to expand tightly against the host pipe wall, completing the rehabilitation process..
Cement-mortar spray-on lining is applied using an electric or air powered machine that coats the existing pipe, using a rotating head, as it moves through the existing culvert. The speed of the machine and application determines the thickness of the liner.
Once the cement-mortar has been applied, a smooth finish is achieved using rotating or conical drag trowels. This method of rehabilitation is usually applied to steel and iron culverts for corrosion protection and adds little structural strength unless reinforced.
Did you know: Vortex Companies offers a variety of culvert rehabilitation products and solutions to make your next culvert rehabilitation project run smoothly. Contact us to help you select the best provider(s) in your area to perform culvert rehabilitation.