As a leading concrete repair specialist, one of Hindle Mason Projects’ (HMP) core competencies is resin injection moulding.
Our solution entails injecting a specialised grout into cracks and voids to fill and seal them. This approach also prevents further damage by strengthening and stabilising concrete around the repaired areas.
Importantly, it is a cost-effective method of repairing concrete structures, as well as efficient and practical to execute. Considering that it involves targeted repair interventions, there is no need for major structural alterations that may interrupt production. Furthermore, by reducing waste and streamlining operations, injection grouting is also safer and more sustainable. This is over-and-above the role that sound repairs play in promoting sustainability by prolonging the lifecycle of concrete structures. Aged or poorly designed and built infrastructure would otherwise have to be demolished and rebuilt. This consumes energy, water and other materials.
HMP deploys resin injection moulding
HMP deploys resin injection moulding in an array of applications. This is in addition to its primary role of sealing, addressing and filling cracks, resulting from wear, tear or structural stress. Our resin injection moulding also protects against water infiltration, which can lead to a range of problems. These include reduced strength, cracking and steel reinforcement corrosion, a leading cause of structural failure. Refer to Reinforcement Corrosion – an overview | ScienceDirect Topics.
Moreover, we use resin injection moulding to stabilise foundations. The technique provides critical support to prevent settlement, while also ensuring even load distribution. This, in turn, reduces the risk of future shifting. Refer to Injection Basics: Applications for Ground Consolidation, Stabilization & Waterproofing.
Our resin injection technology is also an efficient waterproofing system for basements and tunnels. Refer to SikaFix®-210 | Injection Sealing | Tunnelling & Mining.
HMP has also successfully used resin injection moulding many times to fill voids within concrete structures, improving structural soundness.
We have also used this technique to successfully repair concrete columns, restoring strength and preventing further deterioration.
HMP’s resin injection moulding process
HMP’s resin injection moulding process has been refined over more than three decades. We are, therefore, widely accepted as a leader in the field.
We start by drilling holes or “ports” at regular intervals into the concrete, depending on the crack type. This while maintaining a minimum diameter of 2,5cm and a depth of 5cm. Ports are spaced between 150mm and 200mm apart for fine cracks and 150mm to 200mm for major cracks. We maintain a gap of between 300mm and 400mm and keep the port spacing greater than the desired grout penetration depth.
HMP then starts filling the cracks between the ports. This is achieved using polyester, epoxy or cementitious grouts. These materials seal the cracks and provide a stable foundation for the injected grout.
We then clean the cracks and ports to ensure that the grout adheres to the concrete substrate. This step also enables us to work efficiently.
At this stage, we are ready to start setting up the hose connection between the injection equipment and drilled ports. We ensure a secure hose connection seal so that the grout is delivered to the specified areas.
Once we have setup the equipment, we can start injecting the grout under controlled pressure.
We allow at least 24 hours at room temperature for the epoxy to penetrate into the cracks and cure. Thereafter, the ports and excess sealing epoxy is removed. The injection ports are removed by striking them with a trowel or hammer. Meanwhile, the excess epoxy is ground off with an abrasive disk until flush with the concrete surface.
HMP’s resin injection materials
HMP uses various resin injection materials for different applications. They include:
- HMP’s polymer injection grouting. This type of grouting creates a flexible waterproof seal that prevents water ingress and enhances structural stability. Refer to Sika® Injection-203 | PU Crack Injection | Waterproofing and Sika® Injection-307 | Crack & Joint Water Sealing Injection.
- HMP’s fibre-reinforced injection grouting. Containing glass or synthetic polymers, this grout mix has a higher tensile strength and, thus, provides additional reinforcement. This material is very effective in addressing structural integrity-related issues and to prevent crack propagation. Refer to Blog.
- Gas-forming injection grouting. HMP injects a grout mixture that produces gas bubbles within the concrete to effectively fill larger voids and gaps. It also helps to improve the overall density of concrete and reduce its permeability.
- Resin injection. This is another common method that entails injecting specialised resins into cracks. When it hardens, the resin creates a durable bond that effectively seals and reinforces concrete. It is especially suited for the repair of fine cracks. Refer to Sikadur®-52 ZA | Injection Resin to Fill and Seal Voids.
HMP’s suitable resin injection materials
HMP has the knowledge to select the most suitable resin injection materials for specific applications.
For example, a very fast setting repair mortar is needed to plug and stop active water leaks and repair concrete. It is also ideal for sealing cracks and setting ports for concrete injection operations.
To stop water infiltration via cracks and joints, we will use a single component moisture activated polyurethane low viscosity grout. It will also contain Isocyanate Prepolymer (MDI).
However, this is insufficient for large water infiltration. In these cases, we will use a moisture activated polyurethane chemical grout sealant containing MDI. This single component, non-toxic material creates a hydrophobic, rigid and chemically resistant foam. Once the chemical reaction is complete, the foam becomes a completely inert material. Notably, it can expand up to 30 times its volume when it comes into contact with water. We, therefore, also use this material to fill large voids in or behind concrete masonry structures.
Meanwhile, we use a two-component, a100% solids epoxy resin for wicking into horizontal cracks without pressure.
HMP uses a thixotropic two-component epoxy system for all overhead and vertical applications.
HMP’s resin injection moulding equipment
HMP’s resin injection moulding equipment ensures high efficiency on all our projects.
These include well-maintained epoxy injection machines for single, two and plural component applications.
To ensure flexibility, we own piston and membrane pumps that either operate electrically or pneumatically, or by drill or hand.
All of our pumps are well maintained to ensure high availability. This is essential to complete our projects according to the specified quality and within the allocated time. In most instances, we work to tight deadlines to avoid interrupting our clients’ operations. The ability to execute repairs in these environments is one of our strategic competitive edges.
Furthermore, we receive technical support from our equipment suppliers to ensure that our pumps are always “job-ready”.
Du Preez is HMP’s Contracts Director