Axial Compression Performance Research Of Rectangle Hole Burned Shale Perforated Brick Masonry

Since the production of clay brick has been banned in our country,sintered clay brick is gradually eliminated by building materials market,emerged numerous of new building materials,which are sintered shale brick,concrete hollow block and autoclaved block and so on.Among them,sintered shale brick for its easy material availability,processing and building convenience,and have many mechanical propertie advantages as well as sintered clay brick.Thus,sinter shale brick has been widely recognized and accepted.In order to further improve the energy saving effect of the wall,China began to implement the new standard(GB13544-2011)of sintered porous brick and block in 2012,it states that using rectangular hole or rectangle holes instead of round hole and groove of porous brick production.Therefore,the rectangular hole sintered shale porous brick has been heavily promoted and widely available,become the mainstream products of wall materials.To some extent,using rectangular hole porous produce sintered shale brick can reduce the block coefficient of thermal conductivity and improve the energy saving effect of the wall.But in the production of process,high requirements for the fineness of raw materials and plastic,the technical difficulty for rectangle hole forming,easy to deformation crack and in the sintering process,stress concentration of rectangle hole under stress,make the masonry mechanical properties of rectangle hole sintered porous bricks different from circular hole sintered porous bricks.Masonry axial compression effect is the one of most basic and most common stress state.Thus,it is necessary to began a rectangular hole axial compression of sintered shale porous brick masonry performance study.To understand the rectangular hole sinter shaleporous brick masonry deformation performance characteristics under axial compression,and establish a constitutive relation model.Using two kinds of brick,strength grade of MU10 and MU15,KP1 type models(240mm×115mm×90mm),which are common used bricks in Guang Xi,with three kinds of mortar,strength grade of M7.5,M10 and M15,made 6 group 36 standard specimen in all.On the basis of the existing masonry test method standard,use 500 t electric servo pressure testing machine and automatic strain acquisition instrument,completed the axial compression test of all standards specimens,gets axial compression test results of brick and mortar under various combinations,include compressive strength,elastic modulus,peak strain,poisson's ratio and the relatively ideal stress strain curve.The results show that the failure characteristic of rectangular hole sintered shale porous brick masonry are familiar to round hole sintered shale perforated brick masonry.Compressive strength of masonry is mainly decided by the strength of brick and affected less by mortar,comparative analysis the masonry norm of Sovietunion and European and in our country.The three standard compressive strength calculated value tendency are basicly keep consistent with the calculation results,there have high security reserves useing our country masonry norm to calculate rectangular hole sintered shale porous brick masonry.Puts forward two ways of calculation of masonry elastic modulus type(3-2-13)and type(3-2-18),of which type(3-2-13)are good agreement with the test results.Gets the fitting elationship of test results of peak strain and poisson's ratio with the stress ratio changes.By a masonry compression model,explained the masonry compression failure mechanism from the mesoscopic level,according to the theory of damage mechanics and thermodynamics theory,a masonry compression damage balance equation was derived.proposed a damage variable contains initial damage value,combine with the the characteristics of masonry compression stress-strain curve,boundary conditions,and established the masonry,puts a compression constitutive model formula(4-3-11).This model related to the masonry elastic modulus,peak stress and strain.According to the test results of these three parameters,determined the rectangular hole sintered shale porous brick masonry constitutive relation.By comparing with the measured stress-strain curve and the existing achievements of the constitutive relations,verified the rationality of the proposed constitutive relationship model type(4-3-11).It's in good agreement with experiment results,and avoids some shortages existing constitutive relations.