Control of Calcium Carbonate Compound Polymorphism in Cementitious Materials by Self-Healing
Generally, cracking is inherent in reinforced concrete structures and leads to serious damage during its service period.Repeated occurrence of such damages will lead to the enlargement of the cracks, thereby allowing other deteriorating elements such as CO2 and Cl- to 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.This study focuses on the type of CaCO3 crystals generated by the self-healing phenomenon.CaCO3 is crystal polymorphism and its reported that crystal forms can be controlled by the relationship of temperature and pH.Generally, CaCO3 consists of the three kinds, such as calcite, vaterite and aragonite for crystal formation.On the other hand, 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 conditions to generate vaterite.The supplied a saturated Ca(OH)2 solution is used for the effective self-healing.Conditions of the pH are managed pH 9.0-12.0.The results showed that self-healing occurred and the product of the self-healing phenomenon was mostly vaterite to a crystal of CaCO3 under the condition of pH 9.0.
Crack Ca2+ CO32- pH self-healing CaCO3 Vaterite
Risa Sengoku Heesup Choi Masumi Inoue
Department of Civil and Environmental Engineering, Kitami Institute of Technology, Kitami,Japan
国际会议
福州
英文
235-240
2018-11-04（万方平台首次上网日期，不代表论文的发表时间）