• Taha, Hussameldin
• Maddalena, Riccardo
• Gardner, Diane

Abstract

Crack formation is one of the main causes of deterioration in cement and concrete. Cracks in the cover zone lead to fluid ingress and subsequent modification of the pH of the cement matrix. This, in turn may result in disruption to the passive film that protects steel reinforcement, the onset of rust formation and the overall safety of a concrete element being compromised. In this work, we present a comparison between cement mortar mixes using ordinary Portland cement (CEM I) with different replacements of supplementary cementitious materials typically used in the construction industry: silica fume, ground granulated blast-furnace slag (GGBS) and pulverised fuel ash (PFA). Samples were subjected to mechanical damage to open micro-cracks and then placed in a healing bath to trigger autogenous self-healing. The latter occurs via the additional formation of calcium (aluminium) silicate hydrates (C-(A)-S-H) due to further hydration of the starting reactants. Micro-structure characterisation analysis, powder X-Ray diffraction (XRD) and thermogravimetric analysis (TGA/DSC) were used to identify and quantify the hydration products pre- and post-healing. Pore structure and physical property measurements (i.e. open porosity, density, water absorption and sorptivity) were used to determine the effectiveness of the self-healing process in reducing crackwidths and recovering the water-tightness of the mortar matrix post-healing.

Topics

• density
• impedance spectroscopy
• pore
• aluminium
• crack
• steel
• cement
• powder X-ray diffraction
• thermogravimetry
• differential scanning calorimetry
• porosity
• Calcium