The borehole sleeving test method of resin anchored roof bolt instalations

Resin anchored roof bolts are the basis for the primary roof support system of every underground coal mine in Australia. However, the negative influences of uncured resin and resin loss due to installation pressure are common problems despite more than 30 years of product development. The current study details a surface testing method that installs a commonly used roof bolt into lengths of PVC pipe. Results were gathered in two ways, instrumentation measured bolt displacement and rotation speed and back-pressure during installation. The PVC was then cut open to assess the quality of the resin anchor. Comparative testing was undertaken on two resin cartridges commonly used in Australia: 2:1 mastic-to-catalyst resin and 15:1 mastic-to-catalyst resin. The tests were performed in 28 mm and 30 mm internal diameter PVC pipes to simulate a range of underground roof conditions. Data analysis shows the influence of borehole diameter, mastic-to-catalyst ratio and insertion pressure development on resin anchor reliability.