灰分沉淀离析对TLA改性沥青性能的影响

结合佛山一环工程实践,进行了灰分沉淀后不同灰分含量的40%TLA改性沥青的性能对比试验.研究结果表明,随着灰分含量的增加,TLA改性沥青的针入度、残留针入度比、延度和质量损失比降低,而针入度指数、软化点、当量脆点、粘度和相对密度增加.总体上,灰分沉淀离析主要影响TLA改性沥青的低温性能,对感温性能和高温性能也有较大影响,对抗变形能力和抗老化性能有一定的影响,但基本不影响其针入度等级.因此,建议加强TLA改性沥青运输和储存过程中的搅拌,严格控制储存时间,以减少灰分沉淀离析对其性能的影响程度,避免灰分堵塞施工设备管道.

灰分沉淀离析对TLA改性沥青混合料路用性能的影响

结合佛山一环工程实践,进行了灰分沉淀后不同灰分含量的40%TLA改性沥青混合料AC-13C的路用性能对比试验。结果表明,随着灰分含量的变化,空隙率、矿料间隙率、流值和渗水系数增加,而沥青饱和度、稳定度、动稳定度、残留稳定度、残留强度比和构造深度减小,总体上各项路用性能劣化。同时,灰分沉淀离析主要影响TLA改性沥青混合料的抗车辙能力、抗变形能力和密水性能,对承载能力和抗滑性能也具有较大的影响,对水稳性有一定的影响。因此,建议TLA改性沥青混合料的灰分含量相对变化率宜控制在20%以内,且不得超过30%。

Enhanced selectivity of hydrolytic precipitation of Zn from Zn-Ni sulfate solution via chelation of Ni

The selective precipitation of zinc from zinc-nickel sulfate solution with the Zn/Ni molar ratio of20:1was studied.Dropwise addition of0.5mol/L NaOH solution into the zinc-nickel sulfate solution containing0,0.01,0.02,0.03and0.04mol/L ethylene diamine tetraacetate(EDTA)as a chelating agent was done.The equilibrium analysis of precipitation pathway was performed using Visual MINTEQ program.The equilibrium analysis showed that the presence of small amounts of EDTA can prevent nickel precipitation in alkaline conditions without any negative effect on zinc precipitation.On this basis,more than90%of zinc could be precipitated as a product with about50%Zn and only0.11%Ni at pH=9.0merely as a result of the presence of0.03mol/L EDTA in the solution.The stirring time of120min after precipitation was found to be essential for more complete separation.The X-ray diffraction studies on the precipitate revealed that the precipitated phase was Zn4(OH)6SO4.4H2O.