Effect of autogenous healing of narrow and wide cracks on the progression of carbonation in the walls of cracks

Abstract

This paper deals with the carbonation of concrete crack walls before and after healing in comparison to the carbonation of the bulk of the concrete. Natural carbonation tests were carried out on 50 MPa concrete. Disks with 50 mm thickness and 100 mm diameter were tested. A splitting test was applied to generate the crack. Different crack widths were tested, narrow crack widths below 75μm, and wide crack widths, between 75-175μm. The self-healing effect was studied after immersion for 4 months in water. Natural carbonation was carried out at 55±5 %RH 20±3°C for 6, 9 and 12 months. The carbonation front was assessed after splitting and opening the crack walls. The results show the effect of the crack width, crack length and autogenous healing that affect the progression of carbonation in the crack walls. The carbonation in the crack wall is at least twice that of the concrete. Crack widths larger than 75μm carbonate faster. Autogenous healing of the narrow cracks can reduce the carbonation front at the crack walls with compare to the unhealed narrow; however, no improvement was observed in limiting the carbonation front in the crack walls of healed wide cracks.

Keywords

• autogenous self-healing
• non-accelerated carbonation test
• carbonation front
• crack width
• concrete
• corrosion of reinforcement