| With the rapid development of nano-materials technology,the study of application of nano-materials in building materials like mortar and concrete is more and more widely.By adding nano-materials into mortar or concrete,not only better mechanical properties can be obtained,but also special properties such as electromagnetic wave absorption can be obtained.Ferrite materials have high magnetism and strength characteristics,which are suitable for use as the aggregate of mortar and concrete,which not only can reduce the dosage of river sand,but also can make mortar to obtain higher strength and better electromagnetic wave absorption property.Based on the demand of the materials and current research,this study has made the experimental research for the workability,packing density,compressive strength,microstructure and electromagnetic wave absorption property of mortar with single or binary addition of different dosages of nano ferroferric oxide(NFO),micro nickel zinc ferrite(NZF)and micro ferroferric oxide(MFO),and analyzed the relevant influencing mechanisms.The main works are as follows:(1)Workability.By the experimental results of mini slump cone test showed that the workability of mortar would be improved by the single addition of NFO,the workability of mortar would be reduced by the single addition of MFO or NZF,and the reduced effect of NZF is more obvious than that of MFO.When the MFO or NZF mixed with a certain amount of NFO,it can reduce and even eliminate their adverse effects to the workability of mortar.(2)Packing density,compressive strength and microstructure.By the experimental results of packing density,28-day cube compressive strength and scanning electron microscope test showed that single and binary addition of NFO,MFO and NZF can improve the packing density,compressive strength and microstructure of mortar.In the case of single addition,NFO had the best improvement effect,which can increase the packing density and compressive strength by 2.62%and 13.28%respectively at the 1%dosage.The effect of NZF is rank only second to that of NFO,and the packing density and compressive strength can be increased by 2.27%and 7.79%at the 1%dosage,respectively.The increasing effect of MFO is the worst,which can only increase by 2.07%and 6.53%respectively.The improved effect of any co-addition is better than the corresponding single addition group,which shows the combined effects.(3)Electromagnetic wave absorption property.By the experimental results of arch reflection method electromagnetic wave absorption test showed that the three ferrite materials added can improve the electromagnetic wave absorption property of mortar.NFO and NZF have similar improve effects.At the 1%dosage,the maximum absorption peak of mortar can be increased by 15.16%and 13.11%,respectively,and the frequency band bandwidth below-10 dB can be increased by 216.29%and 197.22%,respectively.The improved effect of MFO is the worst.The improved effect of any co-addition is better than the corresponding single addition group,which shows the combined effect.When co-addition of 5%NZF and 2%NFO,the absorption effect of mortar reaches the best,the maximum absorption peak and the frequency band bandwidth below-10dB are increased by50.36%and 446.43%,respectively.(4)The relationship between packing density and compressive strength.According to the40 groups of experimental data of packing density and 28-day compressive strength,the regression formula of packing density-compressive strength was obtained through regression analysis and data fitting.The R~2 value of the formula is close to 0.910,shows a relatively high correlation.It proved that the packing density is one of the key factors of mechanical property of mortar. |
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