UBC Theses and Dissertations
Enhancement of autogenous healing in concrete through internal carbonation Choudhary, Anupam
Self-healing of micro-cracks in cement composites have been widely investigated by cement and concrete researchers in the past two decades. Indeed, most research findings suggest that the self-healing technique could potentially mitigate concrete structure deterioration. Among the various approaches to achieve self-healing in concrete, some involve altering the constituents to enhance the autogenous healing mechanism while others involve incorporating additional healing agents (bacteria, adhesives, crystalline additives). The suitability of these approaches has been discussed in this thesis. The primary contribution to autogenous self-healing is via carbonation, a reaction between hydrated products in concrete with atmospheric carbon dioxide. However, autogenous carbonation-based self-healing has some significant limitations; reduced matrix pH, insufficient carbonation penetration and non-uniform deposition of precipitants in cracks. To offset these limitations, a mechanism that involves the utilization of Sodium Carbonate (Na₂CO₃) solution as a healing agent has been proposed in this study. Multiple aspects of concrete performance, such as compressive strength, tensile strength, permeability and fiber-matrix bond strength were used as parameters to assess whether the proposed solution works better than autogenous healing. To replicate the different types of damages and internal cracking that could arise during the service life of concrete structures, the effects of drying shrinkage, single fiber bond slip and mechanical stresses on the self-healing proclivity of cement-based materials were also explored. A novel technique to measure self-healing under constantly applied stress has also been introduced for better assessment of self-healing.
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