Study On Formula And Performance Of Nano-Modified Protective Agent For Fair-Faced Concreteon

Fair-faced concrete is exposed to the atmosphere for a long time,and is easily damaged by water vapor,carbon dioxide and ultraviolet rays,causing carbonization,yellowing,dim color,pollutant flow marks and other undesirable phenomena,thus seriously affecting the service life and decorative effect of concrete,so painting protective agent on its surface has become a necessary means of protection.At present,fluorocarbon is the best protective agent for fair-faced concrete,but its shortcomings such as high price and poor contamination resistance are the important reasons that restrict its application field and development scale.In order to solve these problems,this paper studies the formulation and performance of a nano-modified fair-faced concrete protective agent,and develops a matching construction technology combined with specific examples.Firstly,the sources,prices and properties of four kinds of nano-materials commonly used in building coatings were analyzed.Among them,nano-CaCO₃ has better comprehensive properties,which is closest to the purpose of modification.Secondly,in order to reduce the price of protectant,the performance test of fluorocarbon emulsion content is divided into 35%,40%,45%,50%,55%five gradients.The results show that when the content of fluorocarbon emulsion is about 40%,the water resistance,alkali resistance,washing resistance,UV aging resistance and adhesion of the coating can meet the requirements of the specification.Then,in order to obtain the corresponding nano-content at the best performance,the effects of nano-CaCO₃ slurry content of 0,2%,4%,6%,8%,10%and 12%on the water resistance,alkali resistance,stain resistance,washing resistance and ultraviolet aging resistance of the coatings were studied.The results show that when the content of nano-CaCO₃ slurry is 8%,the water resistance of the coating can reach 4407h without abnormality,alkali resistance can reach 1861h without abnormality,contamination resistance can be reduced to 2%,washing resistance can reach 89845 times without abnormality,ultraviolet aging resistance can reach more than 70%for 5000h,which is far beyond the requirements of the specification.Finally,based on the external wall of Luoyang Dayu Industrial Co.,Ltd.,the construction process of nano-modified Fair-faced concrete protective agent was studied through the on-site painting test.