| As more and more people realise the scientific development concept of construction energy saving and protecting land resources, the development of the non sintered brick grows quickly. The autoclaved lime-sand brick, one kind of non sintered brick, was widely used in construction. It has good prospect,and it can replace the agglutination loam brick as one kind of new wall materials. The rebound method was widely used in the area of nondestructive testing, for testing the strength of concrete?the masonry brick and the mortar. It won't change the carrying capacity of structure. It has the main characteristic of widely applied, low cost,nondestructive, convenient to use and fast speed. 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.Nowadays, the technical method of using the rebound method to assess the the compressive strength of concrete?the masonry brick and the mortar has growed very maturely. And our country set some relevant standards. However, our country is lack of some related standards in the area of the non sintered brick. To create a healthy environment of the development of the non sintered brick, it is necessary to establish a unified formula on measuring bricksby means of rebound. The research of this article belongs to the basic research of the curve to ascertain autoclaved lime-sand brick strength by rebound method which is part of technical specification for site testing of non firedbrick masonry engineering. The article establish the curve to ascertain autoclaved lime-sand brick strength in hunan province which is based on related test, data analysis, ANSYS/LS-DYNA finite element analysis and the principle of statistics. What have been done in this paper is as follows.(1) The article covers the developing process and prospect of autoclaved lime-sand brick, testing standards at home and abroad nowadays, the principle of testing the compressive strength of autoclaved lime-sand brick by means of rebound method and some factors that may affect the rebound value.(2)We studied the influence mechanism of rebound values of different vertical pressure, distinguished test methods, moisture content and carbonation depth through the compared experiments of 24 standard autoclaved lime-sand bricks in Hunan University.(3) The research employed ANSYS/LS-DYNA finite element analysis software to simulate the process of autoclaved lime-sand brick hit by Schmidt hammer. Meanwhile the paper gets stress nephogram, strain nephogram and some key points' effective strain history under different vertical pressure.(4) Adopting ZC4 type brick rebound hammer to test 48 of standard pieces of autoclaved lime-sand brick in Hunan University and then testing them compressive strength under compression machine, we get 480 groups of R-f data. The data were divided into 26 groups, which were used to regression analysis and fitted by Origin software. Finally we got the rebound hammer strength calculation formula in the style of exponential function.Confirmatory experimental results demonstrated that the degree of accuracy of the rebound strength curve for autoclaved lime-sand brick in existing masonry established in this thesis is high. As a result, it can provide some essential bases for revision of industry standard “technical specification for site testing of non firedbrick masonry engineering”... |
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