Thin spray-on liner adhesive strength test method and effect of liner thickness on adhesion

The adhesive strength between a thin spray-on liner (TSL) and rock is an important property controlling the design and performance of TSL rock support systems. The advantages and disadvantages of various adhesion test methods used by the coatings, microelectronics and concrete industries with respect to TSLs are discussed. A suggested test method for TSL materials is presented, which is based on direct pull-off of an elevator bolt that is attached to a liner with strong epoxy. To interpret the test results correctly, the effect of the liner thickness on adhesive strength must be assessed. This was shown experimentally and was supported by an analytical solution. The adhesive strength is inversely proportional to the square root of the liner thickness. Tests were performed using Tekflex as a liner material, which was applied to concrete or granite substrates.