Bond strength of alkali-activated slag based tunnel fireproof coating material

Abstract The influence of the concentration of sodium hydroxide solution on the tensile bond strength of alkali-activated slags (AAS) used as a tunnel fireproof coating material was studied under the simulated combined action of vibration and wind suction. A test method involving the simultaneous application of vibration and suction was developed and utilized. The test results indicate that as the concentration of sodium hydroxide solution in the AAS increases from 1 to 10 weight percentage, the bond strength of AAS coating improves under the coupling action of vibration and suction. Furthermore, the cumulative pore volume and the average pore diameter in the AAS are reduced and the ratio of harmful pores to total pores decreases. As the concentration of sodium hydroxide solution increases more than 10 weight percentage, however, there is no further benefit in terms of the pore structure and bond strength.