Performance Improvement of Recycled Coarse Aggregate Concrete Using a Shrinkage-Reducing Agent
Performance Improvement of Recycled Coarse Aggregate Concrete Using a Shrinkage-Reducing Agent
复制标题
使用减缩剂改善再生粗骨料混凝土的性能
DOI：
10.1007/978-3-031-32519-9_59
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Hiroyuki Tanano
中科院分区：
文献类型：
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作者：
Sachie Sato;Hiroyuki Tanano
再生骨料混凝土的干燥收缩受粘结剂用量和粘结剂质量的影响，且比原骨料混凝土的干燥收缩显著。因此，日本建筑规范对再生骨料的质量进行了限制，只允许使用高质量的再生骨料。在本研究中，我们探讨了使用中低质量再生粗骨料来提高混凝土性能的方法。我们试图通过稀释减缩剂（SR）并将其喷洒在再生粗骨料上来降低干燥收缩。由于SR可以降低冻融阻力，由于其对夹带的空气量的影响，我们还研究了喷洒稀释SR对冻融阻力的骨料的效果。与混凝土中加入减缩剂相比，SR在骨料表面的浸渍量显著减少，结果表明SR降低了应变。然而，减少的程度取决于结合料和再生骨料的综合质量，往往是微不足道的。这种趋势是由于再生骨料质量的变化。集料中SR的掺入量影响其干缩性能。此外，喷洒SR后，相对动弹性模量随冻融循环的降低速率减小，抗冻融性能提高。
Generally, the drying shrinkage of recycled aggregate concrete is affected by the amount and quality of adhering paste and is more significant than that of raw aggregate concrete. Therefore, the Japanese building code restricts the use of structural members based on the quality of recycled aggregate, and only high-quality recycled aggregate are approved for structural members.In this study, we investigated a method to improve the performance of concrete using low- and medium-recycled coarse aggregates. We attempted to reduce the drying shrinkage by diluting a shrinkage-reducing agent (SR) and spraying it on the recycled coarse aggregates. Because an SR can reduce the freeze–thaw resistance owing to its effect on the amount of air entrained, we also investigated the effect of spraying a diluted SR on the freeze–thaw resistance of the aggregates. The amount of SR that impregnated the aggregate surface was significantly reduced compared to when a shrinkage reducer is added as an admixture to concrete.Results showed that the SR reduced the strain. However, the degree of reduction depended on the combined quality of the binder and recycled aggregate and was often insignificant. This tendency is due to the variation in the quality of the recycled aggregate. The amount of SR that impregnated an aggregate affected its drying shrinkage. In addition, the rate of reduction of relative dynamic modulus of elasticity with freeze–thaw cycles decreased when the SR was sprayed, and the freeze–thaw resistance improved.