Seo Joon Ho, Park Sol Moi, Yang Beom Joo, Jang Jeong Gook
Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Youseong-gu, Daejeon 34141, Korea.
Applied Science Research Institute, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Youseong-gu, Daejeon 34141, Korea.
Materials (Basel). 2019 Apr 23;12(8):1322. doi: 10.3390/ma12081322.
The present study prepared calcined oyster shell powder having chemical composition and crystal structure of calcium oxide and lime, respectively, and investigated the fresh and hardened properties of cement mortar incorporating calcined oyster shell powder as an additive. The test results indicated that the hydration of calcined oyster shell powder promoted the additional formation of Ca(OH) at the initial reaction stage, thereby increasing the heat of hydration. In particular, the volumetric increase of calcined oyster shell powder during hydration compensated the autogenous shrinkage of mortar at early ages, ultimately leading to a clear difference in the shrinkage values at final readings. However, an excessive incorporation of calcined oyster shell powder affected the rate of C-S-H formation in the acceleratory period of hydration, resulting in a decrease in the compressive strength development. Meanwhile, the degree of flow loss was inconsequential and rapid flow loss was not observed in the specimens with calcined oyster shell powder. Therefore, considering the fresh and hardened properties of cement mortar, the incorporation of calcined oyster shell powder of approximately 3% by weight of cement is recommended to enhance the properties of cement mortar in terms of compressive strength and autogenous shrinkage.
本研究制备了分别具有氧化钙和石灰的化学成分及晶体结构的煅烧牡蛎壳粉，并研究了掺入煅烧牡蛎壳粉作为添加剂的水泥砂浆的新拌性能和硬化性能。试验结果表明，煅烧牡蛎壳粉的水化在初始反应阶段促进了Ca(OH)的额外生成，从而提高了水化热。特别是，煅烧牡蛎壳粉在水化过程中的体积增加补偿了砂浆早期的自收缩，最终导致最终读数时收缩值出现明显差异。然而，过量掺入煅烧牡蛎壳粉会影响水化加速期C-S-H的形成速率，导致抗压强度发展降低。同时，流动度损失程度无关紧要，并且在含有煅烧牡蛎壳粉的试件中未观察到快速流动度损失。因此，考虑到水泥砂浆的新拌性能和硬化性能，建议掺入约占水泥重量3%的煅烧牡蛎壳粉，以提高水泥砂浆在抗压强度和自收缩方面的性能。
