Study On High Temperature Characteristics Of Iron Tailings Sand Foam Concrete

Foam concrete is a kind of porous cement material composed of cement,foam and sand.Iron tailings sand is an industrial waste.Its mineral composition is similar to that of natural sand.Therefore,in this experiment,iron tailings sand was used instead of natural sand to prepare foam concrete.It has many good characteristics,such as light weight,thermal insulation,sound insulation and sound absorption,energy saving and emission reduction.At present,foamed concrete is mostly used for thermal insulation of external walls,backfilling of soft soil foundations,interlayers of components,etc.in the construction field.Foam concrete is an inorganic material,and it is a very good natural fire retardant building material.However,when it is in a fire environment,the mechanical properties and physical properties of the foamed concrete after high temperature are deteriorated.However,there are few systematic research results on the performance and structural decline of foamed concrete.Therefore,this article takes iron tailings foam concrete as the research object,and focuses on the performance and structural changes of foam concrete after different high temperature effects,and analyzes the system performance change law.In this test,the orthogonal test was used to make 25 groups of appearance,quality change,compressive strength,and thermal conductivity influenced by the amount of ordinary Portland cement,iron tailings sand and foam as the influencing factors.A 40% iron tailings foam concrete test block was used to observe the changes in pore structure,phase composition and micro-morphology after high temperature,and then use the finite element numerical simulation software to simulate the temperature change of the test block after high temperature action for preparation Compare with the test.The test results show that as the test temperature continues to increase,the appearance of the iron tailings foam concrete test block gradually changes,the color gradually changes from gray to yellow-brown,and the surface gradually changes from the appearance of small cracks to network-like penetration cracks;As the temperature increases,the mass loss of the test block increases,the thermal conductivity increases,and the strength decreases.However,when compared at the same temperature,the more iron tailings sand added,the smaller the loss of mechanical properties of the iron tailings foam concrete.When the amount of iron tailings sand is 40%,the mass loss rate of the test block is less than 20% when the test temperature is 1100?,the strength is about 2.5MPa,and the thermal conductivity is 0.3,so this group was selected for pore structure and microscopic test.Observation of the microscopic test results shows that as the temperature increases,the pore structure of the test block cracks and the pore size gradually increases.When the temperature reaches 1100?,the pores are basically completely destroyed;the iron tailings foam under different temperatures The hydration products of the concrete test blocks are basically the same.When the temperature is between 0°C and 500°C,as calcium hydroxide gradually begins to decompose into a large amount of calcium oxide as the temperature rises,calcium oxide reacts with carbon dioxide in a high-temperature furnace to form carbonic acid Calcium,when the temperature continues to rise,the diffraction peak of calcium carbonate begins to gradually decrease,and calcium carbonate also begins to be decomposed.However,as the temperature continues to rise,the mineral component of which the diffraction peak intensity hardly changes is silica,and the diffraction peaks of the mineral components of magnesium oxide,aluminum oxide,and iron oxide gradually become prominent,and these mineral components all belong to iron tailings.From the microscopic morphology of the test block after high temperature,the internal structure is dense when the test block is heated at 300?;when the temperature is 700 ? to 900 ?,calcium hydroxide accelerates decomposition,and the internal structure of holes and cracks appear;at 1100? At that time,the calcium hydroxide inside the test block has been largely decomposed,and the cementitiousness of the iron tailings foam concrete has been lost.