Research On The Evaluation Of Strength For Autoclaved Fly Ash Brick In Existing Masonry Structures By Rebound Method

Since the reform and opening up and carrying out the principles of giving practical protection to cultivated land and protect the environment, the development of non-sintered brick is becoming more and more mature, at the same time, the application of rebound method is becoming more and more widely. Rebound method is a method for micromasonry testing we usually used, It's principle is:the recoiling rod hit the surface of the specimen under the drive of spring, producing the instantaneous elastic deformation of the resilience which make the hammer drive the movement of the pointer which indicate the distance. We can use the rebound value, one specimen's index of compressive strength, to infer the compressive strength of the specimen. It has the main characteristic of low cost, widely applied, nondestructive. Relevant departments in our country formulate national and local standards of the rebound method testing concrete and sintered bricks, but the rebound method standard about the non sintered bricks is till blank.Since we entering the 12th five-year plan, the problem of environmental governance is becoming an increasing concern, At the same time, it is also an immediate problem. The emissions of fly ash are increasing year by year,in 1994,Determined the spirit of using in the process of fly ash in Comprehensive utilization of fly ash. during the process of making autoclaved fly ash brick, there are many factors influence the quality of brick like raw material handling and equipment, so it caused bad effect in the performance and study of the brick. In summary, it is necessary to establish a rebound strength curve for autoclaved fly ash brick in masonry structure for Hunan area. Through A series of experiments, This thesis used the method of mathematical statistics and regression analysis to establish rebound strength curve for autoclaved fly ash brick in masonry structure for Hunan area. This paper is one of the presumption of industry standard "The method of evaluating the non agglomeration brick strength grading by rebound method". What have been done in this thesis are as follows.(1) This paper covers the developing process and applications, the characteristics of autoclaved fly ash brick, the principle of determination of autoclaved fly ash brick' compressive strength and the factors that main affect the rebound data.(2) By testing specimen's compressive strength of standard s autoclaved fly ash bricks in Hunan University, we have studied the influence mechanism of rebound values of different vertical pressure, mortar, distinguished test methods, rate of water content and depth of carbonation.(3) 348 data of R-f are obtained from the Rebound Test and the compressive test. The data were divided into 42 groups. The data of R-f obtained from the rebound hammer is fitted with the Least Square Method in the style of power function. rebound strength curve for autoclaved fly ash brick in masonry structure for Hunan area is obtained.Confirmatory experimental results demonstrated that the degree of accuracy of the rebound strength curve for autoclaved fly ash brick in existing masonry established in this thesis is high. As a result, it can provide some Experimental basis and enough data to support for revision of industry standard "The method of evaluating the non agglomeration brick strength grading by rebound method".