Effect of Different Calcium Carbonate Sources on the Reinforcement of Aeolian Sand by CFPK
Calcium bicarbonate from pseudo-karstification solution(CFPK)is a kind of environment-friendly sand-fixation material.The source of calcium carbonate has an important influence to the preparation and characteristics of CFPK solution.In order to provide reference for the promotion of application of CFPK in sand fixation,four materials,namely pure calcium carbonate,biological calcium carbonate,light calcium carbonate and heavy calcium carbonate were selected as calcium carbonate sources for preparing CFPK.The sand fixation effects of CFPK solutions prepared by different calcium carbonate sources were analyzed through chemical tests,mechanical tests,X-ray diffraction tests and scanning electron microscopy tests.The results show that a)the conductivity and calcium ion concentration of CFPK solutions pre-pared by four calcium carbonate sources are basically the same when the reaction reaches equilibrium,i.e.,the calcium sources has little in-fluence to the solubility of calcium bicarbonate.However,the difference of reaction rates is obvious,with the fastest reaction rate for heavy calcium carbonate and the slowest for biogenic calcium carbonate.b)The surface strength and wind erosion resistance of different calcium carbonate solidified sands are obviously different.The surface strength and wind erosion resistance of heavy calcium carbonate solidified sand is greater than that of other 3 kinds of calcium carbonate,and the surface strength and wind erosion resistance of biocarbonate solidified sand is the smallest.c)The mineral composition of calcium carbonate crystals generated by the 4 kinds of calcium carbonate sources in the solidi-fied sand is basically the same,and it is mainly calcite.However,the content and morphology of calcium carbonate crystals generated from different calcium carbonate sources in solidified sand are different.The calcium carbonate crystals generated from pure calcium carbonate are mainly hexahedral calcite,and the calcium carbonate crystals generated from the other three types of calcium carbonate are mainly in the form of thin flakes,among which the calcium carbonate crystals generated from heavy calcium carbonate are large in size,highly aggregated and have high densification.Therefore,heavy calcium carbonate as the calcium source has the best sand fixation effect,and it is recommended to choose heavy calcium carbonate as the calcium source for preparing CFPK solution.
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