Torque-controlled adhesive anchors

Hybrid anchors (not to be confused with hybrid adhesives as discussed in 4.3.2) combine the working principles of adhesive anchors with expansion or undercut mechanisms. Torque-controlled adhesive anchors (Figure 4.7) transfer tension loads via friction. Because of their ability to re-expand upon the application of tension loads, they are particularly suited for use in concrete that may crack over the anchor life, and may be used in a variety of applications where the flexibility of an adhesive anchor system is required. They are also less sensitive to hole cleaning procedures than ordinary adhesive anchors. Grouted undercut anchors, like standard undercut anchors, transfer tension loads via bearing. The grout improves the form-fit between the anchor and the concrete thereby reducing initial anchor movement under load. 

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