| Electrolytic manganese slag is an acid waste residue produced in the production process of electrolytic manganese,with the rapid development of electrolyticmanganese industry,the environmental pollution problem caused by electrolytic manganese slag storage is increasingly prominent,seriously restricting the healthy and sustainable development of electrolytic manganese industry,so it is urgent to broaden the resource utilization channels of electrolytic manganese slag,reduce the harm of manganese waste residue,and realize its full quantification and large-scale utilization.At the same time,with the rapid development of China’s transportation industry,the demand for natural road materials has increased sharply.Based on this,this thesis relies on the Chongqing unveiling project"Comprehensive Disposal and Utilization of Electrolytic Manganese Slag"to carry out the application research of stable solidified electrolytic manganese slag in road semi-rigid base materials,which can realize the large-scale utilization of electrolytic manganese slag while saving the cost of pavement base materials,which has important practical significance,good economic and environmental benefits.Based on the physical and chemical properties and leaching toxicity of electrolytic manganese slag,this thesis designs three options,namely cement-manganese slag stabilized crushed stone,lime manganese slag stabilized crushed stone and cement-lime-manganese slag stabilized crushed stone,based on the best moisture content and maximum dry density obtained from compaction test,and selects the best combination ratio based on 7d unconfined compressive strength as the performance index.Further indoor performance tests such as 28d and 90d unconfined compressive strength tests,splitting strength tests,uniaxial compression modulus tests and dry shrinkage tests were conducted to investigate the effect of manganese slag dosing on the road performance of cement-lime-manganese slag stabilised aggregates.Based on the results of the indoor performance tests,the most representative proportions were selected for long-term stability verification and analysis of the strength formation mechanism.Specific findings are as follows:First,the physicochemical properties and leaching toxicity of electrolytic manganese slag were studied.The results showed that the main chemical components of electrolytic manganese slag were Si O2,Al2O3,Fe2O3,Ca O and Mn O.The main mineral components are quartz phase（Si O2）and gypsum phase dihydrate（Ca SO4·2H2O）;The moisture content was 26.9%,p H value was 5.7,and the density was 1.897g/cm3;The leaching concentrations of soluble Mn and ammonia nitrogen are 1220mg/L and149mg/L,which are much higher than GB8978-1996 sewage discharge standards.It is a kind of high moisture content,weak p H value,containing harmful substances Mn and ammonia nitrogen Class II industrial solidwaste.Through the stabilization/curing test,it was found that the curing rate of manganese and ammonia nitrogen in the electrolytic manganese slag under the condition of lime content of 3%can reach 99.98%and98.41%,and the leaching concentrations are 0.147mg/L and 2.36mg/L,respectively,which meet the GB8978-1996 sewage discharge standards of 2mg/L manganese and15mg/L ammonia nitrogen.When the cement content is 5%,the curing rate of manganese and ammonia nitrogen reaches 99.84%and 96.9%,and the leaching concentrations are 1.86mg/L and 4.622mg/L,respectively,which meet the GB8978-1996 sewage discharge standards of manganese 2mg/L and ammonia nitrogen15mg/L.Second,the mechanical road performance of cement-lime-manganese slag stabilized crushed stone materials was studied.The results show that when the cement content is 5%and the electrolytic manganese slag content is 10%～20%,the cement-manganese slag stabilized gravel material meets the 5-7MPa strength requirements of expressway and first-class highway base layer under heavy traffic.When the lime content is 3%,the electrolytic manganese slag content is 20%,30%,40%,the lime-manganese slag stable crushed stone material can meet the strength requirements of 0.8MPa in the bottom layer of highways at all levels;when the cement lime content is 5%（cement:lime=1:1）and the electrolytic manganese slag content is30%～40%,the cement-lime-manganese slag stabilized crushed stone material can meet the strength requirements of 4-6MPa in the secondary and below secondary highway base layer under heavy traffic.The indoor performance test results show that the strength and durability of cement-manganese slag stabilized crushed stone materials are reduced to varying degrees with the increase of manganese slag content.The strength and durability of lime-manganese slag-stabilized crushed stone materials and cement-lime-manganese slag-stabilized crushed stone materials have been significantly improved.Among them,cement-manganese slag stabilized materials with 10%and20%manganese slag content,lime-manganese slag stabilized materials with 30%and40%manganese slag content meet the requirements of mechanical road performance.Third,the secondary pollution of cement-lime-manganese slag-stabilized crushed stone materials was studied.Through dynamic leaching test,it was found that within 20years,the peak leaching concentration of Mn in the simulated sulfuric acid rain of cement-lime-manganese slag was 0.4221mg/L.The highest leaching concentration of ammonia nitrogen is 5.64mg/L,which meets the first-class emission standard of GB8978-1996 and has good environmental protection.Fourth,the strength formation mechanism of cement-lime-manganese slag stabilized crushed stone materials was studied.The results show that the strength of cement-manganese slag stabilized materials mainly comes from the hydration products of cement hydrated calcium silicate gel（C-S-H）and calcium vanadium（AFt）,and with the increase of manganese residue content,it will lead to the reduction of cement hydration products,the compressive strength and durability deterioration.The strength of lime-manganese slag stabilized materials mainly comes from the calcium vanadite generated by the excitation of active minerals in manganese slag under the action of Ca（OH）2,so the increase of manganese slag content has a strong gain effect on its strength and durability.The strength of cement lime-manganese slag stabilized materials is mainly provided by the hydrated calcium silicate gel（C-S-H）,calcium vanadium stone（AFt）and hydrated calcium pyrite generated by the synergy of cement,lime and manganese slag. |
