We are currently renovating a home for our clients in Burnaby who bought the house from the original homeowner who built it in 2004. After deconstruction and removal of frost walls, we noticed there were some fractures in the foundation especially in South East corner of the house. We were especially concerned as this not only a foundation wall but a retaining wall for the attached garage above. As a precaution we advised our clients to scan all the foundation walls to investigate the cause of the cracking.
The engineer for the original house had specified 15mm thick rebar in a 16" x 16" grid but as you can see from the photos the exposed rebar circled in orange indicates that 10mm thick rebar was used. The white chalk lines on these walls represents the horizontal rebar while the blue chalk lines represent the vertical rebar. On the shorter South wall the specified grid pattern was not followed and there is virtually no vertical rebar. There's also horizontal rebar that stops abruptly in one spot indicated by an "x". On the longer length East wall you can see that the horizontal rebar starts to slope downwards and further along this wall (past the vertical stack of 2x4s) the rebar is completely non-existent. This most likely happened when they poured the concrete and the rebar ties failed. This explains the fractures in the concrete as these two walls are not properly supported!
The engineer for the original house had specified 15mm thick rebar in a 16" x 16" grid but as you can see from the photos the exposed rebar circled in orange indicates that 10mm thick rebar was used. The white chalk lines on these walls represents the horizontal rebar while the blue chalk lines represent the vertical rebar. On the shorter South wall the specified grid pattern was not followed and there is virtually no vertical rebar. There's also horizontal rebar that stops abruptly in one spot indicated by an "x". On the longer length East wall you can see that the horizontal rebar starts to slope downwards and further along this wall (past the vertical stack of 2x4s) the rebar is completely non-existent. This most likely happened when they poured the concrete and the rebar ties failed. This explains the fractures in the concrete as these two walls are not properly supported!
For this type of situation we decided it was best to use a Carbon Fibre Reinforcement Polymer (CFRP). Carbon Fiber Reinforcement Polymer (CFRP) is an extremely strong and light fiber-reinforced plastic which contains carbon fibers. CFRP has a tensile strength approximately 10 times that of steel. As a result, it is commonly used wherever high strength-to-weight ratio and stiffness (rigidity) is required, such as aerospace, superstructure of ships, automotive, civil engineering, sports equipment, and an increasing number of consumer and technical applications. This product is also used in both repairing and strengthening of reinforced concrete structures.
Our contracted company used a grinder to smooth all the walls and used epoxy injections to fill a total of 76 lin. ft. of fractures in the concrete. The walls were then primed before applying the vertical and horizontal pieces and they fixed any bubbling that occurred. More resin was applied and heaters were brought in the ensure optimal temperatures and proper curing. A 3rd party company will then do a pull test, measure, and inspect that the CFRP has been adhered properly before they and our engineers sign off on it. All in all this was a two week process. Although this discovery was not expected for our homeowners and comes with an unexpected expense they can now move forward with the rest of their renovation with the peace of mind that their home is safe for their family.
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