水胶比对氧化镁膨胀剂的水化程度及膨胀性能的影响
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摘要
观察了不同水胶比内掺氧化镁膨胀剂补偿收缩砂浆在不同养护制度下(水中养护与密封养护)的自由膨胀率,并结合浆体孔隙率以及显微形貌观察,分析了在较长龄期中不同水胶比条件下的氧化镁膨胀剂的补偿收缩特性。采用XRD-Rietveld法测定不同水胶比条件下氧化镁膨胀剂的反应程度。结果表明:氧化镁膨胀剂发挥作用的最适宜水胶比为0.4,过高或过低都会降低补偿收缩砂浆的膨胀效果。密封条件会使其膨胀效应更早停止。低水胶比使浆体中缺水,因而MgO水化程度较低,同时使浆体结构致密,进而降低补偿收缩砂浆的膨胀量。高水胶比使得浆体内水分供给充足,MgO较快反应完全,进而使得补偿收缩砂浆的膨胀停止较早。
The free expansion rate of shrinkage-compensating mortar containing magnesium oxide expansive agents(MEA) with different water-binder(W/B) ratios was investigated under different curing conditions, i.e., saturated and sealed curing. The porosity and morphology of hardened pastes were investigated. The hydration degree of MgO in pastes with different W/B ratios was measured by X-ray diffraction-Rietveld method. The shrinkage-compensating characteristics of MEA in a relatively long term were discussed. The results show that the suitable W/B ratio is 0.4 for MEA to compensate the shrinkage of mortar. A higher or a lower W/B ratio both reduces the expansion of mortar. Compared to the saturated condition, the expansion of mortars cured in sealed condition stops earlier. A lower W/B ratio results in a densified paste and reduces the pore water quantity for MEA to hydrate, thus reducing the expansion of mortar. A higher W/B ratio provides sufficient water for MEA to hydrate, thus accelerating the MEA hydrates and stoping the expansion of mortar early.
The free expansion rate of shrinkage-compensating mortar containing magnesium oxide expansive agents(MEA) with different water-binder(W/B) ratios was investigated under different curing conditions, i.e., saturated and sealed curing. The porosity and morphology of hardened pastes were investigated. The hydration degree of MgO in pastes with different W/B ratios was measured by X-ray diffraction-Rietveld method. The shrinkage-compensating characteristics of MEA in a relatively long term were discussed. The results show that the suitable W/B ratio is 0.4 for MEA to compensate the shrinkage of mortar. A higher or a lower W/B ratio both reduces the expansion of mortar. Compared to the saturated condition, the expansion of mortars cured in sealed condition stops earlier. A lower W/B ratio results in a densified paste and reduces the pore water quantity for MEA to hydrate, thus reducing the expansion of mortar. A higher W/B ratio provides sufficient water for MEA to hydrate, thus accelerating the MEA hydrates and stoping the expansion of mortar early.
引文
[1]鲁统卫,郑国峰,郭蕾,等.超长大面积无梁楼盖板的施工技术[C].第四届全国混凝土膨胀剂学术交流会论文集,深圳:2006(11):219-220.LU Tongwei,ZHENG Guofeng,GUO Lei,et al.The Proceedings of Forth Symposium on Concrete Expansion Agent[C].Shenzhen,2006(11):219-220.
[2]刘立,朱鹥佳,朱洪杰,等.北京工业大学第三教学楼超长结构的抗裂施工技术[C].第四届全国混凝土膨胀剂学术交流会论文集,深圳,2006(11):409-410.LIU Li,ZHU Yijia,ZHU Hongjie,et al.The Forth Session of the National Academic Symposium of Concrete Expansion Agent[C],Shenzhen,2006(11):409-410.
[3]王世伟.钢管混凝土结构的特性和研究现状[J].安徽建筑,2003(6):64-66.WANG Shiwei.Anhui Archit(in Chinese),2003(6):64-66.
[4]董兰女,程占莲,李弘飞.HL-HGM高强无收缩灌浆料性能及其应用实践[C].第四届全国混凝土膨胀剂学术交流会论文集,深圳:2006(11):626-629.DONG Lannv,CHENG Zhanlian,LI Hongfei.The Forth Session of the National Academic Symposium of Concrete Expansion Agent[C],Shenzhen,2006(11):626-629.
[5]CHATTERJI S.Mechanism of expansion of concrete due to the presence of dead-burnt CaO and MgO[J].Cem Concr Res,1995,25(1):51-56.
[6]邓敏,崔雪华,刘元湛,等.水泥中氧化镁的膨胀机理[J].南京化工学院学报.1990:12(4):1-11.DENG Min,CUI Xuehua,LIU Yuanzhan et al.J Nanjing Inst Chem Tech(in Chinese),1990:12(4):1-11.
[7]莫立武,邓敏.氧化镁膨胀剂的研究现状[J].膨胀剂与膨胀混凝土,2010(1):1-9.MO Liwu,DENG Min.Expan Agent Expan Concr(in Chinese),2010(1):1-9.
[8]MO L,LIU M,ABIR A,et al.Deformation and mechanical properties of the expansive cements produced by inter-grinding cement clinker and MgOs with various reactivities.[J].Constr Build Mater,2015,80:1-8.
[9]MO L,LIU M,ABIR A,et al.Deformation and mechanical properties of quaternary blended cements containing ground granulated blast furnace slag,fly ash and magnesia.[J].Cem Concr Res,2015,71:7-13.
[10]WALENTA G,FULLMANN T,GIMENEZ M.Quantitative Rietveld analysis of cement and clinker[J].Int Cem Rev,2001,6:51-54.
[11]ZHANG R,PANESAR D K.New approach to calculate water film thickness and the correlation to the rheology of mortar and concrete containing reactive MgO[J].Constr Build Mater,2017,150:892-902
[12]MO L,DENG M,TANG M.Effects of calcination condition on expansion property of MgO-type expansive agent used in cement-based materials[J].Cem Concr Res,2010,40(3):437-446.
[2]刘立,朱鹥佳,朱洪杰,等.北京工业大学第三教学楼超长结构的抗裂施工技术[C].第四届全国混凝土膨胀剂学术交流会论文集,深圳,2006(11):409-410.LIU Li,ZHU Yijia,ZHU Hongjie,et al.The Forth Session of the National Academic Symposium of Concrete Expansion Agent[C],Shenzhen,2006(11):409-410.
[3]王世伟.钢管混凝土结构的特性和研究现状[J].安徽建筑,2003(6):64-66.WANG Shiwei.Anhui Archit(in Chinese),2003(6):64-66.
[4]董兰女,程占莲,李弘飞.HL-HGM高强无收缩灌浆料性能及其应用实践[C].第四届全国混凝土膨胀剂学术交流会论文集,深圳:2006(11):626-629.DONG Lannv,CHENG Zhanlian,LI Hongfei.The Forth Session of the National Academic Symposium of Concrete Expansion Agent[C],Shenzhen,2006(11):626-629.
[5]CHATTERJI S.Mechanism of expansion of concrete due to the presence of dead-burnt CaO and MgO[J].Cem Concr Res,1995,25(1):51-56.
[6]邓敏,崔雪华,刘元湛,等.水泥中氧化镁的膨胀机理[J].南京化工学院学报.1990:12(4):1-11.DENG Min,CUI Xuehua,LIU Yuanzhan et al.J Nanjing Inst Chem Tech(in Chinese),1990:12(4):1-11.
[7]莫立武,邓敏.氧化镁膨胀剂的研究现状[J].膨胀剂与膨胀混凝土,2010(1):1-9.MO Liwu,DENG Min.Expan Agent Expan Concr(in Chinese),2010(1):1-9.
[8]MO L,LIU M,ABIR A,et al.Deformation and mechanical properties of the expansive cements produced by inter-grinding cement clinker and MgOs with various reactivities.[J].Constr Build Mater,2015,80:1-8.
[9]MO L,LIU M,ABIR A,et al.Deformation and mechanical properties of quaternary blended cements containing ground granulated blast furnace slag,fly ash and magnesia.[J].Cem Concr Res,2015,71:7-13.
[10]WALENTA G,FULLMANN T,GIMENEZ M.Quantitative Rietveld analysis of cement and clinker[J].Int Cem Rev,2001,6:51-54.
[11]ZHANG R,PANESAR D K.New approach to calculate water film thickness and the correlation to the rheology of mortar and concrete containing reactive MgO[J].Constr Build Mater,2017,150:892-902
[12]MO L,DENG M,TANG M.Effects of calcination condition on expansion property of MgO-type expansive agent used in cement-based materials[J].Cem Concr Res,2010,40(3):437-446.