摘要
纳米材料可有效改善水泥基的力学性能和耐久性,为探索纳米SiO_(2)、Fe_(2)O_(3)对混凝土材料的增强机理,研制力学性能更优的混凝土,制备了0%~2.0%掺量范围内单掺纳米SiO_(2)、纳米Fe_(2)O_(3)、复掺纳米SiO_(2)和纳米Fe_(2)O_(3)的混凝土试件,对养护龄期为7 d及28 d的混凝土力学性能开展试验研究,结果表明:纳米材料总掺量为1.5%且纳米SiO_(2)掺量为1.0%、纳米Fe_(2)O_(3)掺量为0.5%时改性混凝土的力学性能达到最优,该复掺比例改性混凝土比普通混凝土及同掺量的单掺改性混凝土具有更优异的力学性能。采用冷场发射扫描电镜对纳米改性混凝土内部微观形貌进行观察,并借助能量分散谱仪分析纳米改性混凝土的化学成分,结果表明掺入的纳米SiO_(2)及纳米Fe_(2)O_(3)会发生晶核作用并与Ca(OH)_(2)晶粒发生化学反应,在混凝土内部分别生成珊瑚状、球状水化产物C-S-H凝胶及C-F-H凝胶,晶核的高活性吸附凝胶在其表面聚集,减少Ca(OH)_(2)晶粒的数量,并互补填充形成密实的水化产物,使混凝土结构更加紧实致密。研究成果可为高性能混凝土的研发提供参考。
Nano-materials can effectively improve the mechanical properties and durability of cement-based materials.In order to explore the strengthening mechanisms of nano-SiO_(2)and nano-Fe_(2)O_(3)on concrete materials,concrete specimens are mixed with nano-SiO_(2)only,nano-Fe_(2)O_(3)only,and both nano-SiO_(2)and nano-Fe_(2)O_(3)in the range of 0%-2.0%,respectively,to carry out an experimental research on the mechanical properties of concrete with curing ages of 7 d and 28 d.The results shows that the mechanical properties of modified concrete reach the best when the total content of nano-materials is 1.5%,in which the content of nano-SiO_(2)is 1.0%and nano-Fe_(2)O_(3)is 0.5%,and that modified concrete with this compound ratio has better mechanical properties than ordinary concrete and single-mixed modified concrete with the same content.Cold field emission scanning electron microscope is used to observe the internal micro morphology of the nano-modified concrete,and the chemical composition of the nano-modified concrete is analyzed with the help of energy dispersive spectrometer.It can be found that the mixed nano-SiO_(2)and nano-Fe_(2)O_(3)will have crystal nucleation and chemically react with Ca(OH)_(2) crystal grains to form coral-like and spherical hydration products C-S-H gel and C-F-H gel in the concrete.The highly active crystal nucleus can adsorb gel gathering on the surface,which will reduce the number of Ca(OH)_(2) particles and complementarily fill the gap to form dense hydration products,making the concrete structure more compact and dense.These results can provide reference for the research and development of high performance concrete.
作者
黄灵芝
赵鹏龙
司政
柯梅尉
杜晓奇
HUANG Lingzhi;ZHAO Penglong;SI Zheng;KE Meiwei;DU Xiaoqi(School of Water Conservancy and Hydropower,Xi’an University of Technology,710048 Xi’an,China;Shaanxi Weihe Ecological Group,710068 Xi’an,China)
出处
《应用力学学报》
CAS
CSCD
北大核心
2023年第4期788-796,共9页
Chinese Journal of Applied Mechanics
基金
国家自然科学基金资助项目(No.51879217)
联合基金项目-企业-引汉济渭联合基金资助项目(No.2021JLM-46)。
关键词
纳米改性混凝土
复掺比例
力学性能
水化产物
晶核作用
nano-modified concrete
mixed ratio of nano admixture
mechanical property
hydration product
crystal nucleation reaction
