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As experts in comprehensive waterproofing solutions from diagnostic to post-project preventative maintenance, the Danrae Group team is fully experienced with every type of waterproofing issue, from minor leaks to major storm damage or extensive concrete cancer.
Crack injections, for instance, are an efficient and cost-effective option to repair concrete cracks. Here’s when and how we use crack injections for our clients in strata, commercial, government, civil and construction.
Formed from a combination of cement and water, concrete is strong, durable and a mainstay in construction. Concrete may crack for a number of reasons, including extreme high or low temperatures, shifting foundations or excess water in the concrete mixture. Most often however, cracks arise with the normal shrinkage that occurs over time when concrete dries and hardens.
Cracks range in severity and can be non-structural or structural. They may pose an immediate safety issue or be merely unsightly – so expert diagnosis is crucial to understand the type of crack and the optimal repair method.
It’s imperative to know if we are dealing with a structural or non-structural crack, and also if it’s dormant or active. Cracks arising from damage, shifting foundations or concrete shrinkage are active in the initial stages, meaning they are expected to continue to grow. Some cracks may stabilise and become dormant, in which case further growth is unlikely.
Crack injections are low cost, reliable and high-quality solutions to repair concrete cracks and prevent further damage to your property. There are two types of crack injection: epoxy and polyurethane, which are both chemical resins.
Epoxy resins provide structural integrity, so we generally use them to repair structural cracks where concrete strength is important. For aesthetic repairs, and to prevent water ingress for non-structural cracks, we usually opt for a polyurethane crack injection.
Epoxy crack injections are mixed from two parts resin and one part hardener. Curing times range from three to four hours at a temperature of 25 degrees Celsius. Once completely dry, they form a hard plastic type material.
Polyurethane crack injections typically contain resin and an activator – also called an accelerator – but they may sometimes contain additional parts. Once cured, polyurethane most often resembles a rubber. Given polyurethane expands, we use it to fill large cracks that extend from the interior to the exterior wall. Unlike epoxy, polyurethane is also flexible, so it will retain structural integrity with normal building movement. Many polyurethanes cure within 15 to 45 minutes, but it will depend on the specific ingredients used.
There are multiple techniques for crack injection – low or high pressure – and application may involve a gravity injection or injection packer.
The first step is to prepare the crack and surrounding area, as correct preparation ensures full adherence of the epoxy or polyurethane. We may set several injection pins into the crack at intervals, or dynamic cracks may require v cutting to allow for future structural shifts.
Crack injections are an effective option to repair anything from fine to major structural concrete cracks, to prevent water ingress and the onset or deterioration of related issues such as concrete spalling or concrete cancer.
Should your property have any further waterproofing issues, we will repair and fix all issues simultaneously, to ensure you have a sound and comprehensive waterproofing solution in place.
The Danrae group team are experts in diagnostic, solution design, remediation and waterproofing, so we provide holistic and long-term waterproofing solutions that include ongoing preventative maintenance.
Unit 3/1-3 Whyalla Place
Prestons NSW 2170
Level 1, 1 Burelli Street,
Wollongong NSW 2500