养护条件对粉煤灰地聚物混凝土早期收缩性能的影响
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摘要
为推进粉煤灰地聚物混凝土的应用,通过与粉煤灰混凝土对比,探究了粉煤灰地聚物混凝土包裹养护条件下早期抗压强度和不同养护条件下收缩性能的发展情况。结果表明:相较于粉煤灰混凝土,粉煤灰地聚物混凝土包裹养护条件下28 d微观结构密实,且抗压强度增长速率在7～28 d较为显著。干燥养护条件下粉煤灰地聚物混凝土早龄期1 d收缩率较大,此后随着龄期的增长收缩幅度先增大后减小,90 d收缩率大于粉煤灰混凝土;包裹养护下90 d收缩率均小于干燥养护,归因于塑料薄膜隔绝了试件内部水分的蒸发;水中养护14 d龄期前均发生有害膨胀,之后呈现不同程度的收缩,90 d粉煤灰地聚物混凝土收缩率略低于粉煤灰混凝土。此外,进一步拟合出干燥和包裹养护条件下两种混凝土的经时收缩关系式,以期为工程构件的早期裂缝预防提供理论依据。
In order to promote the application of fly ash geopolymer concrete,and compared with fly ash concrete,the development of early compressive strength and shrinkage performance under different curing conditions of fly ash geopolymer concrete was explored.The results show that the microstructure of fly ash concrete is dense compared with fly ash concrete after 28 days,so the growth rate of compressive strength is more obvious in 7～28 days.The shrinkage of fly ash concrete during early age 1 day under drying curing is larger,then with the increase of age,the rate of shrinkage increases firstly and decreases then,the shrinkage of 90 days is greater than fly ash concrete.The every shrinkage of 90 days under packaging curing are less than drying curing mainly because the plastic film stops the water within specimen lossing.It also presents that two kinds of concretes before 14 days under water curing both have an expansion hazard and then they present different degrees of shrinkage,this contributes to the data that fly ash geopolymer concrete is slightly lower when compared to the shrinkage of 90 days fly ash concrete.In addition,the time-dependent shrinkage relationship of fly ash geopolymer concrete under drying and packaging curing is further fitted to provide a theoretical basis for early crack prevention of engineering components.
In order to promote the application of fly ash geopolymer concrete,and compared with fly ash concrete,the development of early compressive strength and shrinkage performance under different curing conditions of fly ash geopolymer concrete was explored.The results show that the microstructure of fly ash concrete is dense compared with fly ash concrete after 28 days,so the growth rate of compressive strength is more obvious in 7～28 days.The shrinkage of fly ash concrete during early age 1 day under drying curing is larger,then with the increase of age,the rate of shrinkage increases firstly and decreases then,the shrinkage of 90 days is greater than fly ash concrete.The every shrinkage of 90 days under packaging curing are less than drying curing mainly because the plastic film stops the water within specimen lossing.It also presents that two kinds of concretes before 14 days under water curing both have an expansion hazard and then they present different degrees of shrinkage,this contributes to the data that fly ash geopolymer concrete is slightly lower when compared to the shrinkage of 90 days fly ash concrete.In addition,the time-dependent shrinkage relationship of fly ash geopolymer concrete under drying and packaging curing is further fitted to provide a theoretical basis for early crack prevention of engineering components.
引文
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[3]毛明杰,韩军召,张文博.粉煤灰等体积替代细骨料混凝土泌水性能研究[J].科学技术与工程,2015,15(30):206-208,213.
[4]孙伟,缪昌文.现代混凝土理论与技术[M].北京:科学出版社,2012.
[5]郑娟荣,姚振亚,刘丽娜.碱激发胶凝材料化学收缩或膨胀的试验研究[J].硅酸盐通报,2009,28(1):49-53.
[6]陈大卫.地质聚合物干燥收缩和反应机理的研究[D].哈尔滨:哈尔滨工业大学,2016.
[7]刘永道,卢都友,郑彦增,等.不同养护条件下含石英玻璃地质聚合物砂浆的变形行为[J].硅酸盐学报,2012,40(5):696-702.
[8]刘志勇.不同温湿度环境粉煤灰混凝土与基准混凝土收缩性能试验研究[J].土木工程学报,2009,42(5):69-73.
[9]刘娟红,宋少民.活性粉末混凝土-配制、性能与微结构[M].北京:化学工业出版社,2013.