THREADBAR® Resin Anchored Rock Bolts
DYWIDAG THREADBAR® reinforcing steel is intended for use in relatively low strength rock bolt and rock dowel applications. DYWIDAG THREADBAR® prestressing steel is intended for use in high strength application to permit the maximum design load in each borehole. The use of prestressing steel may allow a reduction in the number of bolts in the pattern and thus, it usually reduces drilling costs. After drilling, each borehole must be cleaned with either air or water before the resin cartridge is installed. Standing or flowing water does not affect the resin but may cause deterioration of the hole.
DYWIDAG THREADBAR® may be stressed to proof load an anchor or to induce a permanent load. The continuous threadlike deformations simplify stressing. Stressing is accomplished using a center hole hydraulic jack, torque wrench, or air wrench. The anchorage length varies with the structure of the rock formation. The properties of the polyester resin do not govern the design of the bond zone length. All design assumptions should be verified by field tests.
Polyester resin grout is unaffected by blasting and provides a corrosion protection equal to cement grout. Resin is unaffected by fresh water, salt water, mild alkalis and mild acids. The resin gel time and cure time are temperature sensitive. To ensure proper behavior, the ambient temperature of the rock or concrete must be monitored.
The borehole and cartridge diameter must be compatible with the diameter of the THREADBAR® specified. Borehole diameters other than those suggested by the Resin Yield Chart may be used under special conditions. For these applications, testing may be necessary to demonstrate that the tools and procedures selected will sufficiently mix the resin with the catalyst. Anchor plates vary in size and thickness depending upon the function and the bearing conditions. Bevel washers, flat washers, or anchor nuts are required for DYWIDAG Reinforcing Steel. Wedge washers may be used with prestressing THREADBARS® where the plate is not perpendicular to the THREADBAR®.