Strength Characteristics Analysis Of Activated F Grade Fly Ash Cement Mortar And High Content Fly Ash Concrete

Mixing fly ash into cement concrete can not only solve the environmental pollution problem of fly ash but also save the amount of cement and improve economic benefits.However,with the increase of fly ash content in concrete,the strength of concrete will decrease correspondingly,because the potential activity of fly ash has not been fully stimulated.This paper takes fly ash of a power plant in Henan as the main research object,focuses on analyzing the strength enhancement effect of various excitation methods on fly ash cement mortar,as well as the difference of mechanical properties between high-content fly ash cement concrete and ordinary Portland cement concrete,and obtains the optimal fly ash content value and the corresponding mix ratio.Referring to the results of previous experimental studies,the excitation methods used in this paper mainly include the combination of physical,chemical and steaming excitation methods.Through the analysis of the fly ash cement system by the macroscopic strength relationship and the microscopic SEM scanning electron microscope,the mechanical properties of high content fly ash concrete and the strength relationship of high content fly ash cement mortar,as well as the basic principle of fly ash activity excitation are obtained.Aiming at the characteristics of low early strength and slow hydration reaction of highcontent fly ash concrete,three excitation methods were used to study the strength of highcontent fly ash cement mortar and cement concrete.On the basis of the general content(less than 40%),the fly ash content is increased to more than 50%.Based on the strength comparison and SEM analysis results,the optimal coupling content of the activator of the chemical excitation method activated fly ash is anhydrous sodium carbonate 1%,anhydrous calcium chloride 3% and anhydrous sodium sulfate 2%.The optimal mixing ratio of fly ash activated by physical excitation method is ground fine ash: ordinary ash = 1:2.5;The optimal constant temperature curing temperature of steaming activated fly ash is 60℃.Under the optimal conditions,the high-content fly ash concrete was prepared and compared with ordinary Portland cement concrete in uniaxial compressive strength,triaxial stress-strain relationship,elastic modulus and vertical strain.Based on the mechanical properties of high fly ash concrete and the degree of active activation of fly ash,a kind of mix ratio of high fly ash concrete is proposed,which provides a reference for the study of high fly ash concrete.