{"title":"石灰基膨胀材料和冻融循环对混凝土气泡堵塞的影响","authors":"Hidehiko Ogata, Momona Otsuka, Masahiro Hyodo, Haruka Ikadatsu","doi":"10.3151/jact.21.1008","DOIUrl":null,"url":null,"abstract":"</p><p>Air voids in concrete are sometimes observed to be blocked by white precipitates. In this study, the authors conducted freeze-thaw tests on concrete mixed with lime-based expansion material and then performed microscopic observations using scanning electron microscopy, elemental analysis using energy-dispersive X-ray spectroscopy. The size distributions of air voids in the concrete during the curing period (28 days after placement) and before, during, and after the tests were also measured in order to investigate the effects of the expansion material on air-void blockage as well as the underlying processes. During the curing period, no air-void blockage was observed. However, as the concrete aged, precipitates formed on the inner surfaces of the air voids. During the freeze-thaw tests, the number of air voids with diameters of ≤0.15 mm decreased, and the air-void spacing factor increased as the relative dynamic modulus of elasticity decreased. It was found that freeze-thaw cycles caused calcium-based precipitates to form inside the air voids of concrete mixed-with lime-based expansion material, and that the air voids became blocked.</p>\n<p></p>","PeriodicalId":14868,"journal":{"name":"Journal of Advanced Concrete Technology","volume":null,"pages":null},"PeriodicalIF":1.6000,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Effects of Lime-Based Expansion Material and Freeze-Thaw Cycles on Air-Void Blockage in Concrete\",\"authors\":\"Hidehiko Ogata, Momona Otsuka, Masahiro Hyodo, Haruka Ikadatsu\",\"doi\":\"10.3151/jact.21.1008\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"</p><p>Air voids in concrete are sometimes observed to be blocked by white precipitates. In this study, the authors conducted freeze-thaw tests on concrete mixed with lime-based expansion material and then performed microscopic observations using scanning electron microscopy, elemental analysis using energy-dispersive X-ray spectroscopy. The size distributions of air voids in the concrete during the curing period (28 days after placement) and before, during, and after the tests were also measured in order to investigate the effects of the expansion material on air-void blockage as well as the underlying processes. During the curing period, no air-void blockage was observed. However, as the concrete aged, precipitates formed on the inner surfaces of the air voids. During the freeze-thaw tests, the number of air voids with diameters of ≤0.15 mm decreased, and the air-void spacing factor increased as the relative dynamic modulus of elasticity decreased. It was found that freeze-thaw cycles caused calcium-based precipitates to form inside the air voids of concrete mixed-with lime-based expansion material, and that the air voids became blocked.</p>\\n<p></p>\",\"PeriodicalId\":14868,\"journal\":{\"name\":\"Journal of Advanced Concrete Technology\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.6000,\"publicationDate\":\"2023-12-19\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Advanced Concrete Technology\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://doi.org/10.3151/jact.21.1008\",\"RegionNum\":4,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"CONSTRUCTION & BUILDING TECHNOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Advanced Concrete Technology","FirstCategoryId":"5","ListUrlMain":"https://doi.org/10.3151/jact.21.1008","RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"CONSTRUCTION & BUILDING TECHNOLOGY","Score":null,"Total":0}
引用次数: 0
摘要
混凝土中的空气空隙有时会被白色沉淀物堵塞。在这项研究中,作者对掺有石灰膨胀材料的混凝土进行了冻融试验,然后使用扫描电子显微镜进行了微观观察,并使用能量色散 X 射线光谱进行了元素分析。此外,还测量了混凝土在养护期(浇筑后 28 天)以及试验前、试验中和试验后的气孔大小分布,以研究膨胀材料对气孔堵塞的影响以及其基本过程。在养护期间,没有观察到气泡堵塞现象。然而,随着混凝土的老化,气隙内表面形成了沉淀物。在冻融试验中,直径≤0.15 毫米的气孔数量减少,气孔间距系数随着相对动态弹性模量的降低而增大。研究发现,冻融循环导致掺有石灰膨胀材料的混凝土空隙内形成钙基沉淀物,空隙被堵塞。
Effects of Lime-Based Expansion Material and Freeze-Thaw Cycles on Air-Void Blockage in Concrete
Air voids in concrete are sometimes observed to be blocked by white precipitates. In this study, the authors conducted freeze-thaw tests on concrete mixed with lime-based expansion material and then performed microscopic observations using scanning electron microscopy, elemental analysis using energy-dispersive X-ray spectroscopy. The size distributions of air voids in the concrete during the curing period (28 days after placement) and before, during, and after the tests were also measured in order to investigate the effects of the expansion material on air-void blockage as well as the underlying processes. During the curing period, no air-void blockage was observed. However, as the concrete aged, precipitates formed on the inner surfaces of the air voids. During the freeze-thaw tests, the number of air voids with diameters of ≤0.15 mm decreased, and the air-void spacing factor increased as the relative dynamic modulus of elasticity decreased. It was found that freeze-thaw cycles caused calcium-based precipitates to form inside the air voids of concrete mixed-with lime-based expansion material, and that the air voids became blocked.
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Scope:
*Materials:
-Material properties
-Fresh concrete
-Hardened concrete
-High performance concrete
-Development of new materials
-Fiber reinforcement
*Maintenance and Rehabilitation:
-Durability and repair
-Strengthening/Rehabilitation
-LCC for concrete structures
-Environmant conscious materials
*Structures:
-Design and construction of RC and PC Structures
-Seismic design
-Safety against environmental disasters
-Failure mechanism and non-linear analysis/modeling
-Composite and mixed structures
*Other:
-Monitoring
-Aesthetics of concrete structures
-Other concrete related topics