Influence of crack frequency on reinforcement corrosion in concrete

The relationship between crack frequency and reinforcement corrosion was investigated using two models: (a) reinforced concrete beams, 1.36 m long, containing 0, 1, 4, 8, 12, 16 or 20 parallel sided cracks of equal width giving in each case a sum total width of 2.4 mm and (b) a 4 m long beam containing a 20 mm diameter bar in nineteen segments, ten 352 mm long stainless steel segments and nine 10 mm long mild steel segments which simulated the position of cracks. Corrosion was initiated in (a) by spraying the beams with a 3% chloride solution and in (b) by using concrete dosed with 5% Cl (by weight of cement). The weight loss due to corrosion of the reinforcement was estimated via linear polarisation resistance and/or galvanic current measurements using a zero resistance ammeter. The results obtained from both models suggest that decreasing the frequency of cracking leads to a decrease in corrosion. Possible implications of this finding on the design of concrete structures are discussed.