The influence of mixed nano admixtures on the mechanical properties of concrete

Subjects: Engineering and technical science >> Other Disciplines of Engineering and technical science submitted time 2023-11-10 Cooperative journals: 《应用力学学报》

赵鹏龙 司政 柯梅尉 杜晓奇 黄灵芝

Abstract： Nano-materials can effectively improve the mechanical properties and durability of cement-based materials.In order to explore the strengthening mechanisms of nano-SiO2 and nano-Fe2O3 on concrete materials,concrete specimens are mixed with nano-SiO2 only,nano-Fe2O3 only,and both nano-SiO2 and nano-Fe2O3 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-SiO2 is 1.0% and nano-Fe2O3 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-SiO2 and nano-Fe2O3 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.

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