Influence Of Pore Characteristics On Mechanical Properties Of Autoclaved Aerated Concrete

Owing to autoclaved aerated concrete excels in the use of materials and industrial solid waste,it has gradually become the most promising new wall material.However,various disadvantages caused by the porosity of autoclaved aerated concrete are more and more manifested in the application process.In order to solve these drawbacks and promote the application of autoclaved aerated concrete,the pore characteristics of autoclaved aerated concrete and its effect on the mechanical properties of autoclaved aerated concrete are studied.In this paper,the basic performance tests of the autoclaved aerated concrete?autoclaved aerated concrete specimens?and the base material?without adding aluminum powder and with autoclaved aerated concrete are the same?with different dry density grades?B04,B05,B06AF and B06AAC?as the research object.The experimental results show that the cube compressive strength decreases with the increase of porosity,and the relationship between the two is more consistent with the Ryshkewich formula.The elastic modulus is proportional to the axial compressive strength,and the elastic modulus increases with the increase of axial compressive strength.The relationship between splitting tensile strength and cube compressive strength is linear,and the relation can be expressed as f_ts=0.124 f_cc.Based on the modern testing technology such as SEM and XRD,the morphology and the crystalline phase composition of the autoclaved aerated concrete are described and analyzed,and a preliminary understanding of the pore structure of autoclaved aerated concrete is obtained.XRD test results show that the different proportion of autoclaved aerated concrete's hydration products is slightly different,the hydration products of aerated concrete is mainly Tobermorite,C-S-H and SiO₂,and the hydration products of fly ash aerated concrete are more outflow of Andradite than aerated concrete.SEM test results show that B04 sand aerated concrete in Tobey mainly acicular mullite,the material is relatively sparse,low intensity.The leaf shape of Tobermorite in B05 and B06AF fly ash aerated concrete,and its material is more dense.The Tobermorite in the B06AAC sand aerated concrete are flaky,and its material is more dense.The image analysis method based MATLAB is used to measure and characterize the porosity,pore area distribution,pore size and other pore information of the macro pore of autoclaved aerated concrete.The relationship between the pore size and the cube compressive strength can be expressed as a power function:f_cc=0.15D^-2.74.On account of the pores'Classification in combing of cementitious materials and aerated concrete,and the statistics of the poles information after the MATLAB image processing,the autoclaved aerated concrete is divided into three types:the micropore is less than 0.01mm,the meso pole is between0.01mm and 0.1mm,and the macro pole is more than 0.1mm.Based on the MATLAB,using Monte Carlo method to generate spherical coordinates,set the conditions placed stomatal combined with the Monte Carlo method,generation of meso level 3D random pore model,which can give the definition of material properties,element type,model and grid division,selection of constitutive model and failure criterion,until the loading solution in ANSYS.Based on ANSYS,the cubic compressive strength of autoclaved aerated concrete is basically consistent with the experimental value,and the crack analysis,stress analysis and deformation analysis are basically the same as the actual test trend.