| Tantalum Niobium ore associated lithium mica is the world's largest lithium mica ore deposits in Yichun, Jiangxi Province, Salt Autoclaving Method is a new method for preparation of lithium carbonate and lithium hydroxide, However, a lot of solid waste residue(hereinafter referred to as lithium slag) are produced in the process of preparation. The reasonable application of lithium slag has important significance for resource conservation and environmental protection.White facing mortar is a kind of new decorative mortar with white portland cement as the main cementing material and has wide application for its significant advantages in construction, cost and performance. In this paper, we studied the white cement as the main cementing material, and added some lithium slag to prepare White Portland Cement-Based Decorative Mortar(White PCDM). We have studied the effect of lithium slag on the properties of White PCDM, and have carried out the influence of optimization of aggregate gradation and additives(emulsion powder, cellulose ether, polypropylene fiber, hydrophobe) on the performance of White PCDM, and the effect of interaction of lithium slag and slag powder or lime stone powder on White PCDM performance influence.By analyzing the physical and chemical properties of lithium slag which is induced by chloride pressure boiling method, the results show that the main chemical composition of lithium slag are active SiO2 and Al2O3, the main phase of it are analcite and quartz. And this lithium slag can be used as active admixture of cement based materials for its low content of soluble salt, good pozzolanic activity and low radioactive detection.By analyzing the influence of different degree of lithium slag on the properties of plain cement mortar, the results show that doping lithium slag can decrease the mortar efflorescence, When the content of lithium slag reaches to 20%, the total leachability of alkalis ions on the surface of White PCDM reduce by 14%, the area of efflorescence reduce by 31.0%, the 28 d flexural resistance and compressive strength reduce by 0.88 MPa and 1.9 MPa, the adhesive strength reduce by 0.2 MPa, the 30 min and 240 min water absorption increase by 0.61 g and 1.18 g, and the plastic cracking index increases slightly.The results of White PCDM performance optimization experiment show that it has the best mechanical property, drying shrinkage and hygroscopy when the grain composition is(40-70) mesh :(70-120) mesh = 1 : 1. Emulsion powder in PCDM can improve constructability, reduce drying shrinkage and prolong operation time of White PCDM, When the dosage of emulsion powder is 1.6wt%, the adhesive strength increases by 0.46 MPa, the 30 min and 240 min water absorption reduce by 0.61 g and 1.10 g at the same time. Adding cellulose ether to White PCDM can prolong operation time and improve the water retention, When the dosage of cellulose ether is 0.04wt%, the adhesive strength increases by 0.13 MPa, When its content exceeds 0.04wt%, 28 d strength is lower than the standard requirement. The plastic cracking index is zero when the doping of polypropylene fiber in PCDM reaches to1.2 kg/m3. When hate agent content is 3wt%, water absorption is no longer change, the 30 min and 240 min water absorption reduce by 1.07 g and 2.97 g respectively. The best formula of White PCDM performance: 256 kg/m3 cement, 64 kg/m3 lithium slag, 600 kg/m3(40-70) mesh quartz sand, 600 kg/m3(70-120) mesh quartz sand; doping ratio: 1% water reducer(FDN), 0.2% defoamer(dimethyl silicone fluid), 1.6% emulsion powder, 0.04% cellulose ether, 1.2 kg/m3 polypropylene fiber and 3% hydrophobe.The experiment study on adding Lithium slag and mineral powder shows that when the mineral powder content increases from 0% to 20%, the construction performance is decreased, the 30 min and 240 min water absorption reduce by 0.7 g and 2.44 g respectively; the 28 d flexural resistance and compressive strength increase by 1.83 MPa and 6.07 MPa; the 28 d drying shrinkage reduces by 48.5%; while the increase of mineral powder changes the mortar color to grey gradually. The experiment study on adding Lithium slag and limestone powder shows that the construction performance is enhanced with the increase of mineral powder, When the ratio of lithium slag and limestone powder is 5:15, the shrinkage performance and water imbibition achieve the minimum, the 30 min and 240 min water absorption is 0.62 g and 1.9 g; the 28 d flexural resistance and compressive strength increase by 0.52 MPa and 1.63 MPa when limestone powder content is from 0 to20wt%. |
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