蒸养条件下机制砂混凝土的力学性能及干缩性能  

Mechanical properties and drying shrinkage of manufactured sand concrete under steam curing

作　　者：刘穗虎 曾晓辉[1] 唐卓 谢友均[1] 龙广成[1] 周俊良 马刚 LIU Suihu;ZENG Xiaohui;TANG Zhuo;XIE Youjun;LONG Guangcheng;ZHOU Junliang;MA Gang(School of Civil Engineering,Central South University,Changsha 410075,China;Centre for Green Technology,School of Civil and Environmental Engineering,University of Technology Sydney,Sydney 2007,Australia)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]悉尼科技大学土木与环境工程学院绿色科技中心,澳大利亚悉尼2007

出　　处：《铁道科学与工程学报》2024年第5期1886-1897,共12页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(52078490)。

摘　　要：为推动机制砂在预制混凝土构件中的应用,实现机制砂在建筑行业的更广阔应用,进而有效减缓天然砂资源短缺的问题,通过混凝土抗压强度、动弹性模量和干燥收缩试验等宏观性能测试和扫描电镜测试、压汞测试及显微硬度测试等微观测试方法,探讨养护条件和砂型对混凝土力学性能及干缩性能的影响规律及相应机理。试验结果表明:无论采用河砂还是机制砂,蒸养混凝土相较标养混凝土具有更高的早期力学性能和更低的干燥收缩,但高温导致水化产物分布不均,阻碍了后续的水化反应,使其后期力学性能出现不同程度的劣化。结合微观测试结果可知,孔径粗化、界面过渡区间隙增大和水化产物结构疏松是造成蒸养混凝土后期性能劣化的主要原因,但采用机制砂替代河砂能有效减弱蒸养热伤损效应产生的劣化影响。此外,蒸养机制砂混凝土相较蒸养河砂混凝土具有更高的力学性能和更优的微观结构,具体表现为:蒸养机制砂混凝土孔结构更加细化,界面过渡区间隙更小,同时基体显微硬度均值更高,整体密实度更高。但小于50 nm毛细孔增加将导致蒸养机制砂混凝土干缩变形增大。基于GL 2000收缩模型,通过引入考虑机制砂的影响因子,建立了蒸养机制砂混凝土干燥收缩预测模型,可较准确且有效地进行蒸养机制砂混凝土的干燥收缩预测。The application of manufactured sand in precast concrete components,and the wider coverage of manufactured sand in the construction industry,can effectively alleviate the shortage of natural sand resources.This article investigated the effect and corresponding mechanism of curing conditions and sand patterns through the concrete compressive strength,dynamic elastic modulus,drying shrinkage tests and microscopic tests such as scanning electron microscope tests,mercury injection tests and micro hardness tests.The results show that,regardless of the use of river sand or manufactured sand,steam curing concrete exhibits higher early mechanical properties and lower drying shrinkage compared to standard curing concrete.However,elevated temperatures leads to uneven distribution of hydration products,preventin subsequent hydration reactions,which leads to deterioration of later-stage mechanical performance.Microscopic examination indicates that pore coarsening,enlarged interface transition zones,and a loose structure of hydration products are the primary factors contributing to the degradation of later-stage performance in steam curing concrete.Nevertheless,substituting manufactured sand for river sand effectively mitigates the detrimental effects of steam curing thermal damage.Furthermore,the manufactured sand concrete under steam curing demonstrates superior mechanical properties and microstructure when compared with river sand concrete under steam curing.Specifically,manufactured sand concrete under steam curing has refined pore structure,denser interfacial transition zones and higher average matrix micro hardness values,resulting in an overall higher density.But the increase in capillaries smaller than 50 nm also leads to higher drying shrinkage deformation of manufactured sand concrete.The prediction model for the drying shrinkage of manufactured sand concrete under steam curing was established by introducing the influencing factors of the manufactured sand which is based on the GL 2000 shrinkage model.The prediction

关 键 词：机制砂 蒸养混凝土 力学性能 干缩变形 收缩预测模型 

分 类 号：TU527[建筑科学—建筑技术科学]