Control of the Polymorphism of Calcium Carbonate Produced by Self-Healing in the Cracked Part of Cementitious Materials
Control of the Polymorphism of Calcium Carbonate Produced by Self-Healing in the Cracked Part of Cementitious Materials
复制标题
DOI：
10.3390/app7060546
复制
发表时间：
2017-06-01
影响因子：
2.7
通讯作者：
Sengoku, Risa
中科院分区：
文献类型：
--
作者：
Choi, Heesup;Choi, Hyeonggil;Sengoku, Risa
裂缝是钢筋混凝土结构的固有现象，在使用过程中会造成严重的破坏。这种损伤的反复发生会扩大裂缝，从而允许其他劣化元素如CO2和Cl-进一步渗透混凝土，这会严重损害混凝土结构。本研究的重点是碳酸钙（CaCO 3）晶体产生的自愈现象。由于多晶型，碳酸钙有三种类型的晶体形式-方解石，球霰石，文石-其形成可以控制的温度和pH值。球霰石在这些晶体中具有最高的密度，预计它能够自我修复。因此，进行实验以建立促进球霰石生成所需的条件。采用具有CO2纳米气泡（CN）的饱和Ca（OH）（2）溶液进行有效的自修复。将温度控制在20、40和60 ° C，并且将pH控制在9.0、10.5和12.0。结果表明，在pH值为9.0、温度为40 ℃的条件下，裂纹的自愈合现象发生在表面和内部，自愈合现象的主要产物是碳酸钙晶体中的球文石。此外，添加具有CO2纳米气泡（CN）的饱和Ca（OH）（2）溶液导致表面和内部裂纹的最有效的自修复。
Cracking is an inherent development in reinforced concrete structures and can lead to serious damages during their service period. The repeated occurrence of such damages can enlarge the cracks, thereby allowing other deteriorating elements such as CO2 and Cl- to further infiltrate the concrete, which can seriously compromise the concrete structure. This study focuses on the type of calcium carbonate (CaCO3) crystals generated by the self-healing phenomenon. Owing to polymorphism, CaCO3 has three types of crystal forms-calcite, vaterite, and aragonite-whose formation can be controlled by the temperature and pH. Vaterite has the highest density among these crystals, and it is expected to be capable of self-healing. Therefore, experiments were conducted to establish the conditions required to promote the generation of vaterite. A saturated Ca(OH)(2) solution with CO2 nanobubbles (CN) was employed for effective self-healing. The temperature was controlled at 20, 40, and 60 degrees C, and the pH was controlled at 9.0, 10.5, and 12.0. The results showed that the self-healing of cracks occurred both on the surface and internally, and the main product of the self-healing phenomenon was vaterite in CaCO3 crystals at a pH of 9.0 and a temperature of 40 degrees C. Furthermore, the addition of a saturated Ca(OH)(2) solution with CO2 nanobubbles (CN) resulted in the most effective self-healing of the surface and internal cracks.