Pressure required to cause cover cracking of concrete due to reinforcement corrosion

Tests were carried out to investigate the magnitude of pressure created by corrosion products on steel in reinforced concrete that would cause surface cracking of the concrete cover. Test specimens were 150 mm cubes with 8 mm or 16 mm holes provided at various locations and formed by reinforcing bars. The cracking resistance of cover concrete was measured experimentally by pressurizing the holes, and an attempt was made at its prediction using plastic methods of analysis. Experimental failure pressures were found to be influenced by cover/bar diameter ratio, aggregate size, bar diameter, and bar location. The observed lack of correlation between tensile strength and failure pressure lends support to the suggestion made by other researchers that a fracture mechanics approach may be more appropriate. This suggestion was supported by an unsuccessful attempt to find a relationship between cover thickness and effective plastic strength.