| In today’s society,with the rapid growth of our economy the consumption of energy is more and more,and the environment pollution is becoming more and more serious,so the energy problem and environmental problems have become an important problem we have to pay attention to it,so environmental protection and energy-saving new building materials have become an irresistible trend.Iron tailings foam concrete is a good new building insulation materials,it has light weight,good thermal insulation performance,sound insulation,good fire performance,and other advantages,but also can turn waste into treasure,to protect the environment.In this paper,cement,iron ore powder,fly ash,silica fume and polypropylene fiber,additive as the main raw material,adopts the method of chemical foaming,first by single factor method to experiment research,and analysis of various factors influence on properties of iron tailings foam concrete,and to determine the optimum content of each factor values range: the best dosage of iron ore tail is 25% ～ 35%,foam concrete within the range of the 28 d compressive strength and flexural strength of 28 d obtain maximum are 5.1MPa and 2.9MPa.When the fineness of tailing powder is less than 0.01 mm,the maximum values of 28 d compressive strength and 28 d flexural strength of foamed concrete are 6.0MPa and 3.2MPa respectively.The optimum range of water-cement ratio is 0.45～0.6,in which the maximum compressive strength of foam concrete for 28 d is 5.4MPa.The optimal content of fly ash is 10%～20%,and the maximum compressive strength of foam concrete is 9.8MPa for 28 d in this range.When the optimum content of polypropylene fiber is 0.25%,the cracking degree of foam concrete surface is the least.The optimum content of water reducer is 0.6%-0.8%,and the maximum compressive strength of foam concrete for28 d in this range is 6.6MPa.The optimal content of coagulant promoter is 1%～2%,and the maximum compressive strength of foam concrete within 28 d of this interval is6.2MPa,and the minimum setting and hardening time is 17 h.The optimal dosage of foaming agent is 3%～4.5%,and the maximum compressive strength of foam concrete for 28 d in this range is 6.1MPa.By means of orthogonal test,the influence of water-cement ratio,iron-tailings powder,fly ash and hydrogen peroxide on the 28 d compressive strength,thermal conductivity and dry apparent density of foamed-concrete with different contents was studied.The optimal mix ratio was determined as A4B1C3D4 by using "comprehensive balance method",that is,the water-cement ratio was 0.6,the content of iron-tailings powder was 28%,the content of fly ash was 16% and the content of hydrogen peroxide was 4.5%.Then the relationship between the apparent dry density and other properties of foamed concrete with iron tailings powder was studied: the higher the apparent dry density,the higher the compressive strength and thermal conductivity,but the lower the water absorption.Finally,through the scanning electron microscope analysis of the microstructure of foamed concrete of iron tailings powder,it isconcluded that the pore size,pore morphology and pore distribution of foamed concrete of iron tailings powder change with the change of apparent dry density and water absorption. |
