Study On The Performance Of Concrete Made Of Manganese Slag Admixture

A lot of electrolytic manganese slag will be produced in the smelting process of manganese metal.The dumping of manganese slag not only pollutes the environment,occupies land,but also wastes resources.In order to respond to the national policy,the solid waste resources should be used reasonably to make the manganese slag resource.Due to the effective pozzolanic activity of manganese slag,it is necessary to study the main properties of cement concrete with manganese slag as mineral admixture.It will have good economic and environmental value to analyze various performance indexes of manganese slag cement concrete and apply it to engineering practice.In this paper,the influence of manganese slag as mineral admixture on the performance of cement concrete is studied systematically,including macro performance and hydration microstructure.The innovation achievements and main conclusions of this paper are as follows:（1）When the content of manganese slag is 5%～10%,with the increase of the specific surface area of manganese slag,the concrete not only has better cohesion and water retention,but also has better fluidity.However,with the increase of manganese slag content,the fluidity of concrete decreases,and it is not easy to mix when the content of manganese slag reaches 20%.The slump of cement concrete with manganese slag increases with the increase of water binder ratio.When the content of manganese slag is 5%,the water binder ratio is 0.32,0.37 and 0.42,the slump of concrete is 5.2%,5.6%and 2.4%higher than that of the reference group respectively.（2）With the increase of the specific surface area of manganese slag,the strength of cement concrete with manganese slag is improved.Compared with 55m²/kg manganese slag,the strength of concrete prepared with 115m²/kg manganese slag at all ages is improved.However,with the increase of manganese slag content,the strength of three kinds of fineness（55m²/kg,115m²/kg,115m²/kg）manganese slag cement concrete is reduced.Properly reducing the water binder ratio of manganese slag cement concrete can improve its strength,but it should be considered comprehensively from workability and economic rationality determine.（3）Increasing the specific surface area of manganese slag and reducing the water binder ratio can effectively improve the frost resistance and sulfate corrosion resistance of manganese slag cement concrete.With the increase of age,the quality of durability test of manganese slag cement concrete first increased slightly,then continued to decline,and the finer the manganese slag,the smaller the strength loss;properly reducing the water binder ratio can reduce the mass loss and corrosion resistance coefficient of manganese slag cement concrete,the frost resistance grade of concrete with 0.37 water binder ratio and 10%manganese slag（115m²/kg）content reaches 300times,and the corrosion resistance coefficient is 93%.（4）The increase of manganese slag content and the decrease of water binder ratio have great influence on the hydration process of concrete.With the increase of manganese slag content,the semicircle of Nyquist curve in the high frequency region is more obvious,and R_svalue increases with it,and the three-dimensional structure tends to be perfect;with the decrease of water binder ratio,the high frequency region of water binder ratio 0.37 begins to show Randles shape,and the curve of water binder ratio 0.32has shown standard Randles curve.The amount of manganese slag and the ratio of water to binder will affect the exothermic behavior of the cement concrete.With the increase of the amount of manganese slag and the decrease of the ratio of water to binder,the total exothermic capacity and the exothermic rate of the cement can be effectively reduced.（5）With the increase of the content of manganese slag,the diffraction peak of hydrated calcium silicate increases,and the hydration product Ca（OH）₂is consumed continuously,which leads to the decrease of the diffraction peak of Ca（OH）₂.When the content of manganese slag increases in the range of 0～10%,a large number of fibrous C-S-H gels cover the upper surface of massive Ca（OH）₂,making the concrete more dense.With the increase of hydration age,the diffraction peak of Ca（OH）₂decreased,and that of C-S-H increased.With the increase of the specific surface area of manganese slag,the micro particles and needle like products adhere to the fibrous cementitious surface,forming a dense spatial network structure.