Chemical Grouting involves injecting polyurethane chemical grouts, usually sold as liquid resins, into or around leaks. When the resin contacts water, a chemical reaction occurs, and it expands into a closed-cell foam, which can be flexible and resilient (hydrophilic) or rigid (hydrophobic).
In this article we will cover:
- What is chemical grouting?
- Chemical grout injection cost
- Chemical grouting equipment
- Chemical grouting contractors
What is Chemical Grouting?
Generally, the process of grouting is a construction and repair method in which a pliable substance is applied to cavities between other, harder materials to bond the disparate pieces together and create a solid mass. For example, in brick buildings, mortar is the specific type of grout that holds the walls together; and another of the most common grouting applications is in kitchens or bathrooms, where grout is applied in the channels between tiles to prevent water seepage, mold growth, and damage to the structure behind the tile.
Chemical grouting is a specific technique in which the grouting solution is formulated to react chemically to the surrounding materials in order to form a new bond. In instances where a pool deck needs to be repaired, a specific grout is injected that reacts to water, creating an impermeable seal on an existing crack or leak. Chemical grouts can also be applied directly to soil, turning a weak ground material into a stable substance similar to bedrock, which makes it more suitable to withstand the load of a construction project.
The process of chemical grouting is a five-step process. First, the contractor drills boreholes at the appropriate location. Second, the chemical grout is mixed to proper specifications. After mixing, the grout is injected with a pump through hoses that allow the pressurized grout mixture to move through the boreholes. The process must be monitored carefully. Lastly, the grout must set and cure in order to ensure an impermeable bond between materials.
Chemical Grout Injection Cost
As with most construction projects, the cost of chemical grout injections depends on a wide variety of factors. The cost changes when working on a commercial property versus a residential property, often because commercial property managers can negotiate for discounts per cubic foot over a larger scope of work. The location of the chemical grout injection also influences cost. If the injection points are easier to access, cost will be lower; whereas an injection deep in the ground will be more expensive. Lastly, the cost is influenced by the project itself. Using chemical grout injections to repair a leaking pool deck may cost less than chemical grout injections used to solidify soil under a sinking foundation, because of the complexity of work required.
In general, costs of chemical grout injection can range from $10 per square foot for simple crack repairs to $500 per cubic yard for high-strength repairs using epoxy resins. It is important to contact an experienced grout injection contractor to receive an accurate quote for each project.
Chemical Grouting Equipment
Although not technically a piece of “equipment,” choosing the correct type of chemical grout is important. Grout can be made from sodium silicate, polyurethane, acrylic, or epoxy resin.
Furthermore, as outlined in the process description above, each step of the grout injection application utilizes different equipment. First, to drill the boreholes, the contractor will choose the appropriate type of drill. Rotary drills are used in softer soils; percussion drills work in clay or harder rock formations; and auger drills can be used in shallow injection sites or very soft soils.
Second, mixing the grout requires tanks with agitators to keep the aggregate materials of the grout from settling, as well as storage tanks to hold the various material components of the grout mix. Just like mixing different types of dough for baking, the actual mixing is completed using a mixing apparatus specific to the type of grout, whether that be a paddle mixer, colloidal mixer, or drum mixer.
The injection step requires a series of pieces of equipment that all work together in conjunction. The grout pump creates pressure that pushes the grout through the hoses. The hoses are connected with pressure-resistant fittings to equipment called packers, which are devices that are inserted into the boreholes to control the flow of grout into the crevice.
There are three types of grout pumps: a piston pump creates high pressure, which can be used with grout of both high and low viscosity. Diaphragm pumps create low-pressure, which works best for high-volume applications. Peristaltic pumps can create pressure to pump grouts with a high percentage of solid aggregates.
For injection packers, the two main types are mechanical packers and inflatable packers. Both of these devices ensure the grout is applied to the necessary location by holding the void open. The mechanical packer maintains the space within the void using mechanical joints; whereas the inflatable packers create controlled space using air (like a balloon).
In order to monitor the application of the grout, a contractor requires pressure gauges, flow meters, and data logs. These work together to monitor and control grout pressure, flow rate, and volume for a successful application.
Lastly, of course, contractors working with chemical grout must be protected using Personal Protective Equipment (PPE) and containment systems for safe handling of the chemicals.
Chemical Grouting Contractors
If you are considering a project that requires chemical grout injection, you will need to consider your scope of work and then choose the correct contractor with the right materials, tools, and experience for your needs.
If you need repairs to a commercial pool deck, you need a contractor with expertise in chemical grout application that can stabilize your pool deck structure, reinforce the foundational strength, and fix any existing or possible leaks.
If you are considering a repair or rehabilitation project for your commercial amenity deck in the South Florida area, we would be honored if you considered Bengoa Construction.
