Control of Crystal Polymorphism of CaCo₃ Generated in Cracks of Cementitious Material by Change of Temperature and pH

Volume 1 - Issue 5

Heesup Choi*

Received: March 14, 2018;   Published: March 22, 2018

DOI: 10.32474/OAJBEB.2018.01.000124

Full Text PDF

To view the Full Article   Peer-reviewed Article PDF

Abstract

Generally, crack is inherent in reinforced concrete structures and leads to serious damage in service period. In there, recurrences of such damages will lead to the enlargement of the cracks, thereby allowing other deteriorating elements such as CO2 and Clto further penetrate the concrete, and this can have serious consequences for the concrete structure. On the other hand, in an environment where there is supply of water, concrete structures display “self-healing,” in which some of cracks close up naturally, and this phenomenon is closely associated with the hydrates that are newly generated in the areas of crack formation

In this study, author aimed to the kind of CaCO3 generated by self-healing phenomenon. CaCO3 is crystal polymorphism and it’s reported that crystal form can be controlled by the relationship of temperature and pH. Generally, CaCO3 consist of the three kinds such as calcite, vaterite and aragonite for crystal formation. A vaterite is also generated most densely among these, and self-healing can be expected.

Therefore, an experiment is made for the purpose of establishing the condition to generate a vaterite. The supplied a saturated Ca(OH)2 solution with CO2 nano-bubble is used for the effective self-healing. Conditions of the temperature and pH are managed by 20-60°C and 8.5-12 pH. As a result, it was confirmed that the self-healing conditions of saturated Ca(OH)2 solution, which supplied CO2 nano-bubbles, displayed the most effective self-healing performance in the surface and internal sections of the cracks.>

Keywords: Cementitious material; Crack; Self-healing; CaCO3; Ca(OH)2; CO2; Nano-bubble; Vaterite

Abstract| Introduction| Materials and Methods| Results And Discussions| Conclusion| References|