Study On The Preparation And Performance Of Oil Shale Semi-coke Foamed Cement

China has oil shale resources that rank fourth in the world in terms of reserves.Oil shale resources are often used for burning power generation and dry distillation to extract shale oil.Among them,the extraction of shale oil is accompanied by the production of a large amount of oil shale semi-coke which is a kind of toxic and harmful solid waste.The natural stacking and landfilling of a large amount of oil shale semi-coke will have a serious impact on the ecological environment and ultimately endanger human life.At present,the research on oil shale semi-coke mainly focuses on its combustion performance.However,the annual amount of oil shale semi-coke is huge,so it is necessary to actively explore more resource utilization methods and be able to absorb oil shale semi-coke in large quantities.Based on this consideration,based on the analysis of the physical and chemical properties of oil shale semi-coke,the oil shale semi-coke was used as the admixture of foamed cement to prepare oil shale semi-coke foamed cement that performance was studied.This thesis is mainly developed from the following three aspects:1、The physical and chemical properties of oil shale semi-coke were researched by chemical composition analysis,X-ray diffraction analysis,thermogravimetric analysis,scanning electron microscopy analysis,infrared spectroscopy analysis,specific surface area and aperture analysis.The study found that the inorganic oxides in oil shale semi-coke are mainly SiO₂、Al₂O₃、Fe₂O₃ and CaO.The oil shale semi-coke has a loss on ignition of 3.56%,which is relatively low.It can be considered as an admixture for the preparation of cement products.The mineral components of oil shale semi-coke are quartz,kaolinite and hematite.The morphology of the oil shale semi-coke samples is observed via scanning electron microscope and it is revealed that it is irregular,partially flaky,the surface is smooth,and the inter-particles bonding is relatively loose.In addition,the specific surface area of oil shale semi-coke is 8.83 m²/g and the average pore diameter is 2.84 nm.Oil shale semi-coke foamed cement was prepared with different content of oil shale semi-coke and its dry apparent density,compressive strength and water absorption performance were explored.Comprehensive considerations,the preparation of oil shale semi-coke foamed cement with 10%oil shale semi-coke has a dry apparent density of 456 kg/m³,a 7d compressive strength of1.23 MPa,a 28d compressive strength of 1.38 MPa,water absorption of 33.3%,and the average pore diameter of 1.46 mm.2、Single factor experiments were carried out to study the effects of water-cement ratio,foaming agent content,foam stabilizer content,polypropylene fiber content and water temperature on the properties of oil shale semi-coke foamed cement.Based on the analysis of single factor experiment results,an orthogonal experiment was designed to investigate the influence of the above five factors on dry density,water absorption and compressive strength,and the optimal combination.The experiment found that the optimal combination of dry apparent density is A4（water-cement ratio 0.55）B4（foaming agent content 5%）C3（foam stabilizer content 0.6%）D2（polypropylene fiber content 0.3%）E4（water temperature 60℃）;the optimal combination of water absorption is A1（water-cement ratio 0.475）B1（foaming agent content 3.5%）C4（foam stabilizer content 0.8%）D1（polypropylene fiber content 0.2%）E4（water temperature60℃）;the optimal combination of 7d compressive strength is A1（water-cement ratio0.475）B1（foaming agent content 3.5%）C1（foam stabilizer content 0.2%）D1（polypropylene fiber content 0.2%）E1（water temperature 30℃）;the optimal combination of 28d compressive strength is A1（water-cement ratio 0.475）B1（foaming agent content 3.5%）C3（foam stabilizer content 0.6%）D4（polypropylene fiber content0.5%）E1（water temperature 30℃）.3、Sodium methyl silicate and ferric chloride were added to the oil shale semi-coke foamed cement to study the effects of different water-proofing agents and the amount of water-proofing agent on the performance of the oil shale semi-coke foamed cement.The results show that ferric chloride is more suitable as a waterproofing agent for oil shale semi-coke foamed cement,which can not only reduce water absorption,but also improve the mechanical properties of oil shale semi-coke foamed cement.