A grout suitable for rock and cable bolting must have some expansion to enhance bond and anchorage. It must provide protection to the bolts and cables in aggressive ground conditions, have an early gel time, and achieve a rapid strength development for early support. It must be easily mixed with water to a consistency that will flow through 6mm diameter apertures required when using GRP bolts and into any fractured ground around cable bolt holes. Grout effectiveness can be checked by using a rock bolt/cable bolt pull out test. This should not be carried out until the minimum cure period of 28 days.
CBG Grout is a non-shrink high flow grout comprising Portland Cement, pulverised fuel ash and selected additives.
With modern mining techniques slowly replacing the use of steel work with other means of support, the need for a high strength bolting grout becomes ever more prevalent.
It is well known that rock is relatively strong in compression and weak in tensile, shear and flexural strengths and often requires reinforcing. Further to this, excavated rock and coal surfaces often deteriorate on exposure. Bolting overlapping zones can safely and securely contain rock and coal within the vicinity of the bolts.
The effective anchorage and bonding to the rock by the roof bolts, cable bolts and dowels is achieved by grouting. Thus the selection of the right grout is of paramount importance.