Effect of thermal exposure on the mechanical properties of polymer adhesives

- Effect of temperature and time on the mechanical properties of polymer adhesives was investigated.
- Decrease of strength depends on type of polymer, temperature, time and applied stress.
- Effect of temperature and time on the bond strength of concrete/adhesive/FRP specimens was investigated.
- Bond strength was reduced and the mode of failure changed due to temperature, time and increased bond area.

An experimental research programme was carried out to study the effect of thermal exposure on mechanical properties of three different types of polymer adhesives widely used in the construction industry. All specimens were subjected to 4 different degrees of elevated temperature applied for 4 different exposure times. The compression and tensile strengths, carried out as per ASTM C579 and ASTM C307 respectively, were compared before and after thermal exposure. The majority of deteriorating strengths is due to higher temperature level while most of the deterioration took place after 1 h of exposure time. The decrease of residual compressive and tensile strengths, depends on the type of polymer adhesive, level of elevated temperature, type of applied stress and to a lesser effect on exposure time. The effect of elevated temperature on bond strength using concrete/polymer adhesive/FRP specimens was evaluated using four different test methods namely; slant shear test as per BS 6319 Part 4, tensile bond strength test as per ASTM C952, shear bond strength test as per ASTM D905 and double-face shear bond strength. The residual bond strength was reduced and the mode of failure changed due to the high temperature, prolonged exposure time, type of polymer adhesive and the increase in the surface area of bond.

278