苏州混凝土水泥制品研究院有限公司

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引气剂与凹凸棒土对新拌混凝土触变性能的影响研究
Effecting Research of Air-entraining Agent and Attapulgite on Thixotropy Performance of Fresh Concrete
2016年第4期
混凝土;触变;凹凸棒土;引气剂;底座板
Concrete; Thixotropy; Attapulgite clay; Air-entraining agent; Bottom slab
2016年第4期
1000-4637(2016)04-05-05
中国铁道科学研究院基金项目(2014YJ017); 中国铁路总公司科技研究开发计划课题(2013G008-D)。
刘 竞
中国铁道科学研究院铁道建筑研究所,北京 100081

刘 竞

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摘 要:高速铁路曲线段超高混凝土底座板的形态控制是无砟轨道底座混凝土施工控制难点,针对曲线段超高底座板混凝土在凝结前无法有效保持与定型,导致超高不满足要求及排水坡度不能顺利实现等难题,以混凝土动态处理时(如:泵送、浇筑、振捣)具有良好流变性能,静态放置时(如:抹坡、收坡后)具有良好形态保持能力为目标,通过新拌混凝土坍落度、含气量、屈服应力、坡度保持能力等室内试验以及现场工程试用,研究了引气剂、凹凸棒土等矿物掺合料对混凝土触变性能的影响。结果表明,引气剂与凹凸棒土双掺加入,充分发挥了引气剂在浆体引入大量微型气泡的滚珠、润滑作用与凹凸棒土凝胶在浆体中的纤维状结构与取向网络分布的束缚、托举的复合作用,提高新拌混凝土静态屈服应力至10.28N·m、降低动态屈服应力至5.47N·m,增加静/动态屈服力矩比至1.9,改善混凝土坡度保持能力至95.6%。现场试用情况表明,在泵送压力无明显增加情况下,引气剂与凹凸棒土双掺混凝土硬化后底座超高坡度保持率93%以上,明显优于单掺引气剂的混凝土。 Abstract: The elevation control of concrete bottom slab in curve line section of high-speed railway is difficult because fresh concrete cannot hold its shape and the slope of fresh concrete cannot maintain effectively before concrete hardening. To solve this problem, air-entraining agent and attapulgite clay were used to improve the thixotropy of fresh concrete. Results indicated when air-entraining agent and attapulgite clay incorporated simultaneously, the static yield stress of fresh concrete increased (10.28N·m), the dynamic yield stress decreased (5.47N·m), the ratio between the static and dynamic yield stress increased (1.9), and the ability of holding the shape and slope was improved (95.5%). Moreover, the pumping pressure was not increased obviously. The slope-holding rate of concrete bottom slab in curve line section on site reached more than 93% with air-entraining agent and attapulgite clay simultaneously added which was significantly better than that of fly ash concrete. This is mainly due to fibrous gel structure and orientation distribution of attapulgite clay and spherical air bubbles incorporated by air-entraining agent in fresh cement paste. These will provide valuable and useful references for quality control of concrete bottom slab in curve line section of ballastless track.
英文名 : Effecting Research of Air-entraining Agent and Attapulgite on Thixotropy Performance of Fresh Concrete
刊期 : 2016年第4期
关键词 : 混凝土;触变;凹凸棒土;引气剂;底座板
Key words : Concrete; Thixotropy; Attapulgite clay; Air-entraining agent; Bottom slab
刊期 : 2016年第4期
DOI :
文章编号 : 1000-4637(2016)04-05-05
基金项目 : 中国铁道科学研究院基金项目(2014YJ017); 中国铁路总公司科技研究开发计划课题(2013G008-D)。
作者 : 刘 竞
单位 : 中国铁道科学研究院铁道建筑研究所,北京 100081

刘 竞

摘要
参数
结论
参考文献
引用本文

摘   要:高速铁路曲线段超高混凝土底座板的形态控制是无砟轨道底座混凝土施工控制难点,针对曲线段超高底座板混凝土在凝结前无法有效保持与定型,导致超高不满足要求及排水坡度不能顺利实现等难题,以混凝土动态处理时(如:泵送、浇筑、振捣)具有良好流变性能,静态放置时(如:抹坡、收坡后)具有良好形态保持能力为目标,通过新拌混凝土坍落度、含气量、屈服应力、坡度保持能力等室内试验以及现场工程试用,研究了引气剂、凹凸棒土等矿物掺合料对混凝土触变性能的影响。结果表明,引气剂与凹凸棒土双掺加入,充分发挥了引气剂在浆体引入大量微型气泡的滚珠、润滑作用与凹凸棒土凝胶在浆体中的纤维状结构与取向网络分布的束缚、托举的复合作用,提高新拌混凝土静态屈服应力至10.28N·m、降低动态屈服应力至5.47N·m,增加静/动态屈服力矩比至1.9,改善混凝土坡度保持能力至95.6%。现场试用情况表明,在泵送压力无明显增加情况下,引气剂与凹凸棒土双掺混凝土硬化后底座超高坡度保持率93%以上,明显优于单掺引气剂的混凝土。

Abstract: The elevation control of concrete bottom slab in curve line section of high-speed railway is difficult because fresh concrete cannot hold its shape and the slope of fresh concrete cannot maintain effectively before concrete hardening. To solve this problem, air-entraining agent and attapulgite clay were used to improve the thixotropy of fresh concrete. Results indicated when air-entraining agent and attapulgite clay incorporated simultaneously, the static yield stress of fresh concrete increased (10.28N·m), the dynamic yield stress decreased (5.47N·m), the ratio between the static and dynamic yield stress increased (1.9), and the ability of holding the shape and slope was improved (95.5%). Moreover, the pumping pressure was not increased obviously. The slope-holding rate of concrete bottom slab in curve line section on site reached more than 93% with air-entraining agent and attapulgite clay simultaneously added which was significantly better than that of fly ash concrete. This is mainly due to fibrous gel structure and orientation distribution of attapulgite clay and spherical air bubbles incorporated by air-entraining agent in fresh cement paste. These will provide valuable and useful references for quality control of concrete bottom slab in curve line section of ballastless track.

关键词:
混凝土;触变;凹凸棒土;引气剂;底座板
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(1)相比基准混凝土,加入引气剂的新拌混凝土静、动态屈服应力均有所降低,其经振捣抹坡后的坡度保持能力变差。这是由于引气剂在混凝土浆体内引入了大量的微型球体气泡,这些气泡在浆体中充当了微型滚珠,增加了浆体的流动性,改善了浆体的工作性。
(2)相比基准混凝土,引气剂与凹凸棒土双掺加入,在提高新拌混凝土静态屈服应力的同时,降低了动态屈服应力,新拌混凝土坡度保持能力也得以改善。这主要与凹凸棒土凝胶的纤维状结构以及动静状态下的取向分布有关。凹凸棒土不仅能抵消引气剂对新拌混凝土坡度保持能力的不利影响,还由于其特殊的纤维状结构,在浆体中形成网络结构,对浆体与骨料起到束缚、托举作用,进而改善了新拌混凝土的坡度保持能力。
(3)现场工程试验表明,引气剂与凹凸棒土双掺加入的新拌混凝土用于曲线超高段无砟轨道底座板浇筑施工,在泵送压力无明显增加、施工性能无明显变化的情况下,硬化后的超高坡度保持率在93%以上,新拌混凝土坡度保持能力明显优于单掺引气剂的粉煤灰混凝土。这有利于确保曲线段超高底座板乃至其上充填层的施工质量。
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