Research On Mechanical Properties And Frost Resistance Of Aerated Concrete Prepared With Iron Tailings

This paper focuses on the factors which affects the mechanical properties and frost resistance of the aerated concrete prepared with iron tailings and researches the influence on the mechanical properties and frost resistance of aerated concrete by the lime content,admixtures and pore characteristics.With the micro experiment,the mechanism was analyzed.First of all,the mechanical properties and frost resistance of the aerated concrete were studied with different lime content.Research shows that:(1)with the increase of the lime content,both the mass loss rate and the the strength loss rate increased before the mass ratio reach to 35:60.Furthermore,when the lime and iron tailings mass ratio was 35:60,the frost resistance of the blocks was the worst;when the proportion was 25:60,the higher strength and the better frost resistance could be achieved.(2)with the increase of the lime content,the density of the aerated concrete would decrease until the mass ratio reach to 35:60.Furthermore,when the lime and iron tailings mass ratio was 35:60,the samples could get the minimum density.(3)the hydration products of the aerated concrete were mostly tobermorite and C-S-H.Secondly,in this study,waterborne epoxy resin and calcium stearate were utilized to improve the frost resistance,and the influence of different content on frost resistance was analyzed with XRD and SEM.Research shows that:(1)with the increase of the content of waterborne epoxy resin,the mass loss rate and strength loss rate of the samples were decreasing slowly,when the content reached to 3%,the frost resistance would be improved;when the content reached to 5%,the frost resistance was improved obviously;when the content>5%,the improvement would be weakened.(2)with the increase of the content of calcium stearate,the mass loss rate and strength loss rate of the samples were decreasing slowly,when the content<2%,the improvement could be neglected;when the content reached to 3%,the mass loss rate and the strength loss rate after 15 times freezing-thawing cycles improved obviously,they were 4.126%and 18.457%.Finally,because of the uncertainty of the current pore characteristics test methods of aerated concrete,the Section Image Analysis was proposed to design and apply based on the MATLAB platform.With the method,the influence on the frost resistance which the pore characteristics had was studied.Research shows that:(1)The pore characterization information including the pore porosity,pore size distribution and the average aperture could be extracted by utilizing the method.(2)With the analyses,the sample which use A1 powder as the gas foaming agent got 55.70%of the porosity and 3.01mm of the average pore diameter,the sample which use Al+H2O2 as the gas foaming agent got 60.27%of the porosity and 3.70mm of the average pore diameter,the sample which use Al+A as the gas foaming agent got 57.27%of the porosity and 2.88mm of the average pore diameter.(3)The pore characters not only affect the water absorption,but also affect the frost resistance.That is to say,the more the percent of related big pore get and the larger the pore size become,the higher the water absorption would be and the larger the mass loss rate and strength loss rate would be.