Usually, a diagonal or vertical crack in a poured or block foundation wall that is wider than 1/8", and is located closer to a corner is probably not due to shrinkage but indicates a settlement issue and should be strengthened to prevent further damage from occurring. While piering solutions can stabilize the foundation and possibly recover some of the settlement that has occured it's important to strengthen the corner and reestablish the broken tie in the foundation.
Understanding the two different weaves of carbon fiber and their technical properties has helped foundation repair contractors choose the right product and design based on the type of failure they are repairing. In the case of corner repairs, the goal is to reestablish the broken tie and use all of the ultimate tensile strength of the carbon fiber horizontally around the corner. In this application the SRS-600 Unidirectional Carbon Fiber would be the material of choice since 100% of the strands are running in the same direction, providing over 195,000 psi (1,352 MPa) tensile strength.
To structurally strengthen and confine a vertical crack and prevent water intrusion, SRS-660 Bidirectional can be used in addition to the Unidirectional material. Each tow in the two distinct fabrics contains 12,000 filaments of carbon fiber. In the case of the bidirectional, those tows are split and woven in both directions. This distinct fabric orientation provides strength in both directions, making it an ideal solution for crack repairs in conjunction with SRS-600 Unidirectional corner straps.