• 한국도로학회논문집
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• 제17권3호
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• pp.27-33
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• 2015

PURPOSES : To ensure appropriate RCC properties with sufficient strength development and workability, it is necessary to secure a proper level of consistency. It is also necessary to secure maximum dry density, which is an important factor for increasing the interaction of aggregate interlocking, leading to an augmentation of RCC strength. On the other hand, the dry density of RCC can be changed owing to the compaction conditions, water content, and particle size distribution. A Proctor test and a modified Proctor test were used for determining the optimum water content needed to achieve maximum dry density with different amounts of compaction energy. A Vebe test, on the other hand, was used for checking the level of consistency, which is important for producing a workable mixture. METHODS : To confirm the degree of compaction at various particle sizes, RCC mixtures with different sand/aggregate ratios were evaluated. The Proctor test and modified Proctor test were applied to these mixtures to check the effect of the aggregate gradation and compaction energy on the maximum dry density and optimum water content. During each test, three specimens were produced for all types of water content under each aggregate gradation. A compaction curve and the optimum water content and maximum dry density for each aggregate gradation were then obtained for both tests. The range of water content for the appropriate consistency of each aggregate gradation was determined through a Vebe test. The optimum water content was then evaluated based on this range. RESULTS : The compaction test results show that the modified Proctor test provides a higher maximum dry density and lower optimum water content compared with the standard Proctor test. For the modified Proctor test, two cases of aggregate gradation (s/a = 30% and 70%) had the optimum water contents outside of the appropriate water content range. For the standard Proctor test, on the other hand, none of aggregate gradations provided the optimum water content within the desired range. CONCLUSIONS : The modified Proctor test should be used for an RCC mixture design because it can provide adequacy between maximum dry density and consistency. Moreover, the compaction roller has become highly developed for higher compaction energy.

• 자원리싸이클링
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• 제23권4호
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• pp.47-57
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• 2014

본 논문에서는 비정질 강섬유의 길이 및 혼입률 변화에 의한 섬유보강콘크리트의 작업성과 섬유분산성에 대한 기초연구를 수행하였다. 일반적인 슬럼프시험 외에 역슬럼프 및 베베시험을 이용하여 일반 강섬유와는 외관 및 형상이 다른 비정질 감섬유의 유동성을 평가하였다. 실험결과, 얇은 판상형의 비정질강섬유의 작업성 평가를 위해서는 일반적인 슬럼프시험보다는 진동 하에서 수행된 역슬럼프 및 베베시험을 통한 유동성 평가가 바람직한 것으로 나타났다. 결론적으로 섬유의 혼입률 및 길이 증가는 콘크리트의 유동성을 현저히 감소시켰으며, 시멘트 메트릭스내에서 섬유간 간격 또한 감소시키는 결과를 보여주었다.