Experimental Study On Mechanical Properties And Thermal Properties Of Thermal Insulation Glazed Hollow Bead And Iron Tailings Concrete

As a large industrial waste,iron tailings not only waste resources,but also bring great pressure to the regional ecological environment.The iron tailings used as concrete fine aggregate or mineral admixture can use a large number of iron tailings resources and effectively alleviate the pressure of the shortage of natural sand and gravel resources in the process of rapid urbanization in China and is one of the main ways of comprehensive utilization of iron tailings in China.Thermal insulation glazed hollow bead concrete is a kind of innovative green high performance concrete in the field of building energy efficiency in china.In this paper,based on the research results of thermal insulation glazed hollow bead concrete,the application of iron tailings in thermal insulation glazed hollow bead concrete is studied.The results of this study can provide data support for the technical integration of thermal insulation glazed hollow bead concrete and iron tailings concrete.The main contents and conclusions of this paper are as follows:(1)The chemical composition,mineral composition,particle size distribution and fineness modulus of Jianshan iron tailings are studied.The results show that Jianshan iron tailings belong to Anshan high silicon iron tailings,and its main minerals are quartz and hematite etc;Jianshan iron tailings sand belongs to the II area of medium sand,and the feature of its particle distribution is that particles with particle size less than 150 ?m are too much.(2)After the artificial screening of Jianshan iron tailings,the content of iron tailings powder is 7% and its particle distribution can meet the relevant requirements.On this basis,using iron tailings sand to replace natural sand,and the effect of substitution rate on the basic mechanical properties and thermal performance of thermal insulation concrete is studied.The results show that with the increase of the replacement rate,cube compressive strength,axial compressive strength,splitting tensile strength,flexural strength,elastic modulus,dry density and thermal conductivity of thermal insulation concrete first decrease and then increase and then decrease and then increase.In this paper,it is suggested that we should completely replace natural sand with iron tailings sand.When the substitution rate is 100%,compared with 1-0 the compressive strength is increased by 15% and the thermal conductivity is increased by 14.2%.(3)On the basis of completely replacing natural sand with iron tailings sand,5 kinds of iron tailings sand with different content of iron tailings powder are prepared,and the effect of iron tailings powder content on the basic mechanical properties and thermal performance of thermal insulation concrete is studied.The results show that with the increase of iron tailings powder content from 7% to 19%,the cube compressive strength,axial compressive strength,tensile strength,elastic modulus first decrease and then increase slightly and then continue to decrease,the flexural strength first decreases and then remains the same and then continues to reduce,dry density and thermal conductivity decrease gradually.In this paper,it is suggested that the content of iron tailings powder should be controlled between 13%~19%.When the iron tailings powder content is between 13%~19%,the strength is greater than 1-0 and thermal conductivity is less than 1-0.(4)In order to further improve the utilization rate of iron tailings powder,it is used as a mineral admixture to replace part of cement,and the effect of substitution rate on the basic mechanical properties of thermal insulation concrete is studied.The results show that with the replacement rate increased from 0% to 20%,the cube compressive strength,axial compressive strength,splitting tensile strength and elastic modulus decrease gradually,and the flexural strength first remains the same and then decreases gradually.When the replacement rate is not more than 4%,using iron tailings powder to replace cement has a little influence on the basic mechanical properties of thermal insulation concrete.But when the substitution rate is more than 4%,the mechanical properties decrease obviously,therefore,the replacement rate of iron tailings powder cannot exceed 4%.