Research On The Performance Of Iron Tailing Powder Mechanism Of Its Influence On Concrete

This study main researchesthe iron tailing powder performance and the machanism of effect as a mineral admixture in the concrete.The test choose Beijing Miyun iron tailing power which main chemical composition is SiO2,Al2O3 content is only 8.49%,mineral composition is quartz and chlorite,all for the crystal mineral.When grinding in 45 minutes,the maximum of specific surface area of 680 m2 / kg.The fineness of iron tailing power does not affect the value of MB.With the increase of dosage of iron tailing power,MB value increases,when the dosage of 25%,MB value of 1.5,is greater than 1.4.Scanning electron microscopy(SEM)results showed that iron tailing power for irregular situation,similar to the limestone powder morphology,no similar spherical particles of fly ash.The same water,mixed with 3% ~ 50% iron tailing power can improve the fluidity of cement mortar,and the improvement of grinding powder effect is more significant.The same water/cement ratio,the dosage of iron tailings powder is less than 10%,can improve the compressive strength;When grinding powder content less than 20%,can improve the compressive strength.At the same dosage,grinding ore powder on strength increased more than the original.Adding iron tailings powder can effectively reduce the brittleness of the material,improve the crack resistance.After mixed with iron tailings powder,reduce the hydration heat quantity,the second exothermic peak time slightly delay;Mixed with iron tailings after grinding powder can shorten the second exothermic peak time,promote the early hydration process.The original mineral content is less than 8%,the grinding powder in the design of experiment content(50%),within the scope of its 3d,7d and 28 d hydration activity of the contribution rate of greater than 0,which has a certain role to promote the development of strength.With more than 8% of the iron tailings powder reduces the fractal dimension of cement mortar;With no more than 20% of the grinding powder can improvement points of fractal dimension.The iron tailings powder can refine the pore structure of cement mortar and improve its compactness.When adding iron tail mineral powder and slag powder concrete mixture on the premise of the same slump,as long as the iron tailing power and appropriate proportion of mixed slag powders,and the composite mineral admixture content,appropriate to meet the design requirements under the premise of slump,iron tailings powder grinding of gelled material system is close-grained effect is better than the original kuangfen,compared to the original mineral powder,fine powder grinding concrete,less dosage of water reducing agent.When water-binder ratio at the same time,with the increase of the dosage of admixture,the early strength of concrete is reduced,but the late strength increase obviously,at the same dosage of admixture,with the increase of the proportion of composite iron tailing power,the strength of concrete is reduced.In matching phase at the same time,the compressive strength increases with the increase of fineness of iron tailing power present trends.Iron tailing power using mixing of concrete has good resistance to chloride ion permeability and freezing resistance,and mixed with fine powder grinding is more advantageous to improve the durability performance of concrete.Iron tailing power by micro aggregate filling effect,water reducing effect and promote hydration effect and improve the mobility of the cement concrete strength and durability.Iron tailing power fineness,the greater the three big effect more significant.So the amount of iron in the tail mineral powder mixed with concrete and micro aggregate effect,improve the gelled material gradation,improve liquidity concrete,concrete to obtain good working performance and strength.