Improvement in Early-Age Strength and Durability of Precast Concrete by Shrinkage-Reducing C-S-H
In order to improve early-age strength, steam curing is mostly used for railway prefabricated components, which consumes a lot of energy and affects the durability of concrete. Synthetic calcium silicate hydrate (C-S-H) has an excellent early-age strength effect, which can improve the early-age stre...
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MDPI AG
2025-05-01
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| author | Peiyun Yu Shuming Li Chi Zhang Xinguo Zheng Tao Wang Xianghui Liu Yongjian Pan |
| author_facet | Peiyun Yu Shuming Li Chi Zhang Xinguo Zheng Tao Wang Xianghui Liu Yongjian Pan |
| author_sort | Peiyun Yu |
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| description | In order to improve early-age strength, steam curing is mostly used for railway prefabricated components, which consumes a lot of energy and affects the durability of concrete. Synthetic calcium silicate hydrate (C-S-H) has an excellent early-age strength effect, which can improve the early-age strength of concrete and help to reduce the energy consumption of steam curing, but C-S-H will increase the shrinkage of concrete and affect the durability of concrete. In this work, C-S-H/SRPCA was synthesized using a shrinkage-reducing polycarboxylate superplasticizer (SRPCA) in order to increase the early-age strength and decrease the shrinkage of concrete. The effects of 0.5%, 4.0%, and 8.0% C-S-H/SRPCA on the shrinkage and strength of concrete were studied. Meanwhile, the internal mechanism was also explored through cement hydration, the physical aggregation morphology of hydration products, pore structure and classification, and the chemical properties of pore solution. The results suggest that C-S-H/SRPCA can shorten the setting time and accelerate cement hydration. Specifically, when the dosage of C-S-H/SRPCA is 4.0%, the initial setting time of concrete is shortened by 2.5 h and the final setting time is shortened by 6.2 h compared with the control group. As a result, the 1-day compressive strength is effectively increased by 29.5%, and the plastic shrinkage is reduced. In the stage of plastic shrinkage, the plastic shrinkage time of the concrete with 4.0% C-S-H/SRPCA is 4.1 h, which is 6.1 h shorter than that of the control group. In addition, C-S-H/SRPCA decreases the porosity. When the dosage is 4.0%, the porosity of the hardened cement paste at 28 days is reduced by 15% compared with the control group. It lessens the content of the capillary pores at 10–50 nm. At 24 h, the content of 10–50 nm capillary pores in the paste with 4.0% C-S-H/SRPCA is 40% lower than that of the control group. It also reduces the surface tension of the pore solution. The surface tension of the simulated pore solution with 4.0% C-S-H/SRPCA is 34 mN/m, which is 53% of that of the control group, and it inhibits the volatilization of the pore solution. At 28 days, the evaporation rate of the pore solution in the paste with 4.0% C-S-H/SRPCA is 40% lower than that of the control group. Thus, the drying shrinkage of concrete is inhibited. Given the above, at the optimum content of 4.0%, C-S-H/SRPCA improves the 1-day compressive strength of concrete by 29.5%, reduces the 28-day total shrinkage by 21.7%, and restrains the development of microcracks. |
| format | Article |
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| spelling | doaj-art-fd30201d84f3461ba6844d4e7a87b3e72025-08-20T02:24:47ZengMDPI AGBuildings2075-53092025-05-01159157610.3390/buildings15091576Improvement in Early-Age Strength and Durability of Precast Concrete by Shrinkage-Reducing C-S-HPeiyun Yu0Shuming Li1Chi Zhang2Xinguo Zheng3Tao Wang4Xianghui Liu5Yongjian Pan6Railway Engineering Research Institute, China Academy of Railway Sciences Group Co., Ltd., Beijing 100081, ChinaRailway Engineering Research Institute, China Academy of Railway Sciences Group Co., Ltd., Beijing 100081, ChinaRailway Engineering Research Institute, China Academy of Railway Sciences Group Co., Ltd., Beijing 100081, ChinaRailway Engineering Research Institute, China Academy of Railway Sciences Group Co., Ltd., Beijing 100081, ChinaDepartment of Highway and Railway Engineering, School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, ChinaRailway Engineering Research Institute, China Academy of Railway Sciences Group Co., Ltd., Beijing 100081, ChinaBeijing Tieke Special Engineering Technology Co., Ltd., Beijing 100081, ChinaIn order to improve early-age strength, steam curing is mostly used for railway prefabricated components, which consumes a lot of energy and affects the durability of concrete. Synthetic calcium silicate hydrate (C-S-H) has an excellent early-age strength effect, which can improve the early-age strength of concrete and help to reduce the energy consumption of steam curing, but C-S-H will increase the shrinkage of concrete and affect the durability of concrete. In this work, C-S-H/SRPCA was synthesized using a shrinkage-reducing polycarboxylate superplasticizer (SRPCA) in order to increase the early-age strength and decrease the shrinkage of concrete. The effects of 0.5%, 4.0%, and 8.0% C-S-H/SRPCA on the shrinkage and strength of concrete were studied. Meanwhile, the internal mechanism was also explored through cement hydration, the physical aggregation morphology of hydration products, pore structure and classification, and the chemical properties of pore solution. The results suggest that C-S-H/SRPCA can shorten the setting time and accelerate cement hydration. Specifically, when the dosage of C-S-H/SRPCA is 4.0%, the initial setting time of concrete is shortened by 2.5 h and the final setting time is shortened by 6.2 h compared with the control group. As a result, the 1-day compressive strength is effectively increased by 29.5%, and the plastic shrinkage is reduced. In the stage of plastic shrinkage, the plastic shrinkage time of the concrete with 4.0% C-S-H/SRPCA is 4.1 h, which is 6.1 h shorter than that of the control group. In addition, C-S-H/SRPCA decreases the porosity. When the dosage is 4.0%, the porosity of the hardened cement paste at 28 days is reduced by 15% compared with the control group. It lessens the content of the capillary pores at 10–50 nm. At 24 h, the content of 10–50 nm capillary pores in the paste with 4.0% C-S-H/SRPCA is 40% lower than that of the control group. It also reduces the surface tension of the pore solution. The surface tension of the simulated pore solution with 4.0% C-S-H/SRPCA is 34 mN/m, which is 53% of that of the control group, and it inhibits the volatilization of the pore solution. At 28 days, the evaporation rate of the pore solution in the paste with 4.0% C-S-H/SRPCA is 40% lower than that of the control group. Thus, the drying shrinkage of concrete is inhibited. Given the above, at the optimum content of 4.0%, C-S-H/SRPCA improves the 1-day compressive strength of concrete by 29.5%, reduces the 28-day total shrinkage by 21.7%, and restrains the development of microcracks.https://www.mdpi.com/2075-5309/15/9/1576precast concreteearly-age strengthshrinkageC-S-H/SRPCApore structure |
| spellingShingle | Peiyun Yu Shuming Li Chi Zhang Xinguo Zheng Tao Wang Xianghui Liu Yongjian Pan Improvement in Early-Age Strength and Durability of Precast Concrete by Shrinkage-Reducing C-S-H Buildings precast concrete early-age strength shrinkage C-S-H/SRPCA pore structure |
| title | Improvement in Early-Age Strength and Durability of Precast Concrete by Shrinkage-Reducing C-S-H |
| title_full | Improvement in Early-Age Strength and Durability of Precast Concrete by Shrinkage-Reducing C-S-H |
| title_fullStr | Improvement in Early-Age Strength and Durability of Precast Concrete by Shrinkage-Reducing C-S-H |
| title_full_unstemmed | Improvement in Early-Age Strength and Durability of Precast Concrete by Shrinkage-Reducing C-S-H |
| title_short | Improvement in Early-Age Strength and Durability of Precast Concrete by Shrinkage-Reducing C-S-H |
| title_sort | improvement in early age strength and durability of precast concrete by shrinkage reducing c s h |
| topic | precast concrete early-age strength shrinkage C-S-H/SRPCA pore structure |
| url | https://www.mdpi.com/2075-5309/15/9/1576 |
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