摘要
为探究复掺纳米二氧化硅(NS)和碳纳米纤维(CNF)再生混凝土经历低温环境后(-10℃、-20℃、-30℃)的力学性能,首先以NS掺量、CNF掺量、再生骨料(RA)取代率为影响因素设计正交试验,确定常温环境下NS与CNF的最佳掺量与RA取代率,然后进行复掺NS和CNF改性再生混凝土经历低温环境后的力学性能试验,最后通过扫描电镜图像分析纳米材料的改性机理。结果表明:各因素对再生混凝土抗压强度与劈裂抗拉强度的影响程度依次为RA取代率>CNF掺量>NS掺量;NS与CNF通过成核效应、火山灰活性及纤维与基体的桥接作用改善了再生混凝土的裂缝及孔隙结构,使再生混凝土获得更加致密的微观结构,进而提高了再生混凝土的抗压及劈裂抗拉强度。最后得出NS与CNF的最佳掺量分别为3%、0.2%;复掺NS与CNF能够显著降低再生混凝土抗压强度与劈裂抗拉强度对低温环境温度变化的敏感程度,且对劈裂抗拉强度有较大提高,最大提高幅度达到17.3%。
To study the mechanical properties of compounded nanosilica(NS)and carbon nanofibre(CNF)recycled concrete after experiencing low-temperature environments(-10℃,-20℃,-30℃).Firstly,an orthogonal test was designed with NS dosage,CNF dosage and recycled aggregate(RA)substitution rate as the influencing factors to determine the optimum dosage of NS and CNF and RA substitution rate under ambient temperature environment.Then the mechanical property tests of compounded NS and CNF-modified recycled concrete after experiencing low-temperature environment were carried out,and finally the modification mechanism of nanomaterials was analysed by scanning electron microscope images.The results show that the degree of influence of each factor on the compressive strength and splitting tensile strength of recycled concrete is in the following order:RA substitution rate>CNF admixture>NS admixture.NS and CNF improved the crack and pore structure of recycled concrete through nucleation effect,filling effect,volcanic ash activity and bridging effect between fibres and matrix,so that the recycled concrete obtained a denser microstructure,which in turn improved the compressive and splitting tensile strength of recycled concrete.Finally,it is concluded that the optimum mixing amount of NS and CNF is 3%and 0.2%,respectively.compound mixing of NS and CNF can significantly reduce the sensitivity of compressive strength and splitting tensile strength of recycled concrete to changes in low-temperature ambient temperature,and improve the splitting tensile strength by a large amount,with a maximum increase of 17.3%.
作者
程东辉
陈深深
王丽
侯越方
CHENG Donghui;CHEN Shenshen;WANG Li;HOU Yuefang(School of Civil Engineering and Transportation,Northeast Forestry University,Harbin 150040,China;School of Architecture and Civil Engineering,Qiqihar University,Qiqihar 161006,China)
出处
《混凝土》
北大核心
2025年第5期69-75,91,共8页
Concrete
基金
国家自然科学基金(51908108)
中央高校基本科研业务费创新团队与重大项目培养资金项目(2572016EBC1)
黑龙江省教育厅基本科研业务项目(135309358)。
关键词
纳米二氧化硅
碳纳米纤维
再生混凝土
低温环境
基本力学性能
nano-silica
carbon nanofibres
recycled concrete
low temperature environment
basic mechanical propertie
作者简介
第一作者:程东辉(1971-),男,博士,教授,主要从事预应力混凝土和新型建筑材料研究。联系地址:黑龙江省哈尔滨市香坊区和兴路26号东北林业大学土木与交通学院(150040),联系电话:13895797262。
