Optimization mix design of bridge deck concrete based on crack resistance in alpine regions(PDF)
长安大学学报（自然科学版）[ISSN:1006-6977/CN:61-1281/TN]
- Issue:
- 2019年04期
- Page:
- 1-8
- Research Field:
- 道路工程
- Publishing date:
Info
- Title:
- Optimization mix design of bridge deck concrete based on crack resistance in alpine regions
- Author(s):
- GUO Yinchuan; CHEN Zhihui; SHEN Aiqin; LI Peng
- （Key Laboratory of Highway Engineering in Special Region of Ministry of Education， Chang‘an University， Xi‘’an 710064， Shaanxi, China）
- Keywords:
- road engineering; recommended value of mix proportion; shrinkage test; anti cracking performance; alpine region; microscopic mechanism
- PACS:
- -
- DOI:
- -
- Abstract:
- In order to solve the early shrinkage cracking problem of bridge deck concrete in alpine regions, the concrete working environment of the alpine regions were simulated, the dry shrinkage and plastic shrinkage tests of water cement ratio were conducted, and the effects of the cement and superplasticizer on the cracking performance of the bridge deck concrete were determined. By using SEM electron microscopy, concrete shrinkage cracks and the evolution process of the micro analysis were clearly identified, and the design proposal for the alpine region based on the crack resistance of concrete bridge deck was presented. The results show that the water cement ratio is an important factor affecting the early shrinkage and crack resistance of the concrete bridge panel in the alpine area. The high water cement ratio was helpful in improving the early shrinkage and crack resistance of the concrete deck C40 bridge and it was conducive to the early age curing the infiltration of water. However, a water cement ratio higher than 0.49 would appear inferior when the crack resistance of concrete mixed plastic and the trend increase, the dosage of cement increased significantly in the 7 d panel concrete shrinkage crack, accelerated through shaping, and increased further to 80 kg/m3, shaping the cracking time would advance 20 min, the though time would be shortened 32 min, so based on the dry shrinkage and plastic shrinkage test results, the best mixing amount should be controlled within 260~300 kg/m3. The superplasticizer was added to refine the initial crack concrete, which made it appear more deterioration trend and its meso crack width was in contraction increased for bridge deck concrete work requirements, the content should be controlled between 0.5%~0.8%; 5 d before the bridge deck concrete shrinkage value accounted for more than 7 d total shrinkage of 80%, and reached the peak at fifth days, it should be as far as possible to extend the curing time to fifth days to reduce early the hydration shrinkage crack. 1 tab, 13 figs, 23 refs.
Last Update: 2019-07-29