Effect of rock strength and surface roughness on adhesion strength of thin spray-on liners

This paper discusses the results of a series of tests developed to examine the link between substrate strength and surface roughness on the adhesion strength of thin spray-on liners (TSLs). Laboratory adhesion tests were conducted using grout substrates with different uniaxial compression strength (UCS) and surface roughness. Two different TSL materials were used for the tests. Steel dollies were glued onto the surface of the TSL with a strong epoxy and then pulled in tension to measure the adhesion strength. The results of the experiment suggest that both rock strength and surface roughness play a significant role in determining the adhesion strength of TSLs. As the rock strength increases, the adhesion strength also increases significantly for the lower strength substrates tested and then levelled out as the substrate strength further increased. Both TSLs exhibited large increases in adhesion strength when the substrate was changed from a flat to a rough surface. As the surface roughness for rough profile substrates increased, there was also slight increase in adhesion strength of TSLs.