Study On The Performance Of Alkali-activated Blast Furnace Slag-manganese Slag Cement Mortar

At present,the research and application of raw materials for alkali-activated cementitious materials at home and abroad are mainly based on blast furnace slag.With the development of research applications,the supply of slag cannot keep up with demand.Many researchers at home and abroad have begun to study the incorporation of other industrial waste residues,waste substitution(or partial replacement)of slag into the alkali-activated system.China has a large stock of manganese slag and high annual output.Most of the manganese slag is directly stacked in the open air,occupying land resources,polluting soil and water sources.Manganese slag is incorporated into the alkali-activated cementitious material system instead of slag.This can not only alleviate the current contradiction between supply and demand of slag,improve the current situation of large amounts of waste and pollute the environment,but also improve existing defects of alkali-activated slag cementitious materials,and enrich and develop alkali-activated cementitious material systems.This project is based on alkali-activated slag cement mortar,using Na OH as an activator.The response surface method was used to optimize the mixture ratio of alkali-activated slag cement mortar to obtain a excellent fluidity and mechanical properties.A new type of alkali-activated blast furnace slag-manganese cementitious material is prepared by incorporating manganese slag into the alkali-activated slag system to partially replace slag.In this project,the effect of water-to-binder ratio,manganese slag content and alkali content on the fluidity and mechanical properties of alkali-activated slag-manganese slag cement mortar was studied.In comparison with alkali-activated slag cement mortar and portland cement mortar,the properties of alkali-activated blast furnace slag-manganese slag cement mortar in water absorption,drying shrinkage and chemical resistance were studied.Analyze the hydration products and microstructure of alkali-activated blast furnace slag-manganese slag cement mortar by microscopic means.The research of this subject provides a certain reference value for the application of manganese slag in alkali-activated gelling material system.The main conclusions are as follows:1.The research results of the influence of water-binder ratio,manganese slag content and alkali component content on the fluidity and mechanical properties of alkali-activated blast furnace slag-manganese slag cement mortar show that the water-binder ratio and manganese slag content are important factors affecting the mortar fluidity factors,the alkali equivalent has little effect on the fluidity of the mortar;the water-binder ratio,the manganese slag content and the alkali equivalent all have a great influence on the mechanical properties of the mortar.When the water-binder ratio was 0.45,the manganese slag content was 15 % and alkali content is 6%,the fluidity and mechanical properties of the mortar are better.2.The alkali-activated blast furnace slag-manganese slag cement mortar has lower fluidity than the alkali-activated slag cement mortar,the hydration reaction is slow,and the early strength is low.However,an appropriate amount of alkali-activated slag-manganese slag cement mortar with appropriate manganese slag content is beneficial to the later strength growth.3.The performances of water absorption,shrinkage and chemical resistance of alkali-activated blast furnace slag-manganese slag cement mortar were studied by comparing portland cement mortar and alkali-activated slag cement mortar.The test results show that the alkali-activated slag-manganese slag cement mortar has high water absorption and good chemical resistance,and the shrinkage performance is greatly improved compared with the alkali-activated slag cement mortar.4.The hydration process and microstructural changes of alkali-activated blast furnace slag-manganese slag cement mortar were analyzed by microscopic methods such as hydration heat,electrochemical AC impedance,XRD and scanning electron microscope tests.The results show that the alkali-activated blast furnace slag-manganese slag cement mortar has a low hydration reaction rate,low hydration heat.In the early stage of the hydration reaction,there were many unhydrated particles in the mortar,and the microstructure was not dense enough.Compared with alkali-activated slag cement mortar,new hydration products are generated.