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Title |
Early-age Shrinkage Cracking of Fiber Reinforced Mortar Produced with Bio-Polymer Admixtures
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Authors |
김효정(Hyo-Jung Kim) ; 이병재(Byung-Jae Lee) ; 김윤용(Yun-Yong Kim) |
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DOI |
https://doi.org/10.4334/JKCI.2023.35.6.583 |
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Keywords |
바이오 폴리머; 메틸셀룰로스; 선인장 줄기 미분말; 소성수축 bio-polymer; methylcellulose; cactus stem powder; plastic shrinkage |
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Abstract |
This study examined the effect of polymer admixtures and reinforcing fibers on the characteristics of fresh mortar such as plastic shrinkage and setting time. In addition, the possibility of using biopolymer as a substitute for synthetic polymer admixture was evaluated. As a result of the setting time tests, the initial setting time was delayed as the amount of Cactus Stem (CS) used as the Methyl Cellulose (MC) substitute increased. This is most likely because the cellulose structure, which increased according to the amount of CS added, interfered with the reaction between cement and water, delaying the setting time. As a result of plastic shrinkage tests up to 12 hours of age, the crack area was reduced by about 16 % when part of MC was replaced with CS, compared to when MC was mixed alone. It is likely that the setting-retarding effect of CS appeared as a decrease in crack area. Cracks were not observed in the fiber-reinforced mortar mixed with MC and CS, indicating good performance in controlling shrinkage cracks at early age. As a result of testing the length change of mortar under the same conditions as the plastic shrinkage tests, the fiber-reinforced mortar mixed with MC and CS showed the smallest shrinkage. Comparisons of the compressive strengths at 1, 3, and 7 days of age indicates that the mortar strengths mixed with MC and CS were found to be at a similar level regardless of the presence of reinforcing fibers.
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