Durability And Modification Mechanism Of Nano-modified Concrete

As one of the materials widely used in civil engineering,concrete’s performance has always been the focus of attention.So far scholars have found that the mechanical properties of concrete is not the whole cause of concrete damage,and its durability is also a decisive factor,so scholars gradually turn their attention to the durability of concrete.With the development of nanotechnology,it has become the trend of concrete development to improve the performance of concrete from microcosmic angle.In particular,the durability of nano-modified concrete in recent years has a broad prospect and application value to improve its the salt-frost resistance.This paper takes nano-SiO₂ and nano-Al₂O₃ to modify the ordinary concrete and the concrete mixed with fly ash,as well as select r GO/GO to modified the cement mortar.And the dosage of nanometer material by mass of cement is less than 1%.And the study adopts the water reducer as the surfactant and the ultrasonic method is used to disperse the nanometer materials,then mixing with the concrete aggregate form the concrete and cement mortar.Then the workability,mechanical properties,and salt-frost resistance of the nano-modified concrete and cement mortar were tested.In addition,the modification mechanism was studied by scanning electron microscopy（SEM）and energy dispersive spectroscopy（EDS）as well.When the content of nanometer material by cement is less than 1%,the experimental results show that the nano-modified concrete and cement mortar have no obvious change on the workability.The compressive strength and the compressive strength increase with the increase of the dosage of the content.When the dosage reaches 1%,the mechanical properties reach the maximum.The resistance of salt-frost is same to the compressive strength and the compressive strength.The application of nano-SiO₂ to modified the ordinary concrete and the concrete mixed with fly ash is better using nano-Al₂O₃ to impove mechanical properties,and salt-frost resistance.It is r GO rather than GO that can improve the mechanical properties and salt-frost resistance of concrete.Compared with the ordinary concrete and the concrete mixed with fly ash which modified by nano-SiO₂ and nano-Al₂O₃,it is not obviously different.Meanwhile,after 3days and 7 days,analysis of mechanical performance of the fly ash concrete which modified by nano-SiO₂ and nano-Al₂O₃,it shows that can improve the early strength of concrete,and can effectively improve the defects of low early strength of fly ash concrete.Analysis of the modification mechanism of the modified concrete using of the SEM and EDS,nanomodified concrete will become coarse and appear nano fiber.Hence it can effectively impove density and prevent the development of micro cracks of concrete,so the performance of concrete has been improved.The r GO/GO plays a template role in process of hydration reaction,which can be obtained the more compactly hydrochemical C-S-H.So it can improve the performance of the cement mortar and concrete.