碱对低热水泥早期水化进程和微结构的影响
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摘要
通过外掺Na_2SO_4的方式,将低热水泥中的碱含量(质量分数,下同)提高至0.80%,1.20%和1.60%.利用微量热仪研究了以硫酸盐形式存在的碱对低热水泥早期水化进程的影响,并通过水化动力学模型具体分析了碱对低热水泥各水化阶段的影响,最后利用29Si和27Al固体魔角核磁共振技术,研究了碱对低热水泥水化产物中含Al相和含Si相组成结构的影响.结果表明:碱能促进低热水泥的水化,但在一定碱含量范围内,低热水泥的水化并不随着碱含量的增加而显著增加,这种促进作用主要是由于碱提高了水泥结晶成核和晶体生长速率,并延长了相边界反应阶段;此外,碱在一定程度上促进了低热水泥中的Al向C-S-H链中转移,但随着碱含量的增加,Al在C-S-H链中的相对含量降低,更倾向于向六配位的AFt中转移.
The alkali content(by mass,the same below)of low-heat cement was adjusted to 0.80%,1.20% and 1.60% by adding Na_2SO_4.Isothermal calorimetry test was used to investigate the influence of alkali on early age hydration process of low-heat cement.The influence of alkali on the hydration stage of low-heat cement was analyzed by the hydration kinetic model.The structure of silicon phase and migration form of the aluminum phase in low-heat cement hydration products were observed by 29 Si and 27 Al magic angle spinning nuclear magnetic resonance.The results show that alkali can promote hydration process of low-heat cement,but the hydration process does not increase with the increment of alkali content in certain content.The promotion effect of alkali on low-heat cement is mainly due to increase of nucleation and crystal growth rate of low-heat cement and the stage of interaction at phase boundaries is prolonged.Besides,alkali is more likely to increase aluminum substitution ratio in calcium silicate hydrate(C-S-H)chain and the degree of polymerization of C-S-H.However,with the increment of alkali content,aluminum tends to shift to ettringite(AFt)rather than to C-S-H chain.
The alkali content(by mass,the same below)of low-heat cement was adjusted to 0.80%,1.20% and 1.60% by adding Na_2SO_4.Isothermal calorimetry test was used to investigate the influence of alkali on early age hydration process of low-heat cement.The influence of alkali on the hydration stage of low-heat cement was analyzed by the hydration kinetic model.The structure of silicon phase and migration form of the aluminum phase in low-heat cement hydration products were observed by 29 Si and 27 Al magic angle spinning nuclear magnetic resonance.The results show that alkali can promote hydration process of low-heat cement,but the hydration process does not increase with the increment of alkali content in certain content.The promotion effect of alkali on low-heat cement is mainly due to increase of nucleation and crystal growth rate of low-heat cement and the stage of interaction at phase boundaries is prolonged.Besides,alkali is more likely to increase aluminum substitution ratio in calcium silicate hydrate(C-S-H)chain and the degree of polymerization of C-S-H.However,with the increment of alkali content,aluminum tends to shift to ettringite(AFt)rather than to C-S-H chain.
引文
[1]JAWED I,SKALNY J.Alkalies in cement:A review:II.Effects of alkalies on hydration and performance of Portland cement[J].Cement and Concrete Research,1978,8(1):37-51.
[2]ODLER I,WONNEMANN R.Effect of alkalies on Portland cement hydration:I.Alkali oxides incorporated into the crystalline lattice of clinker minerals[J].Cement and Concrete Research,1983,13(4):477-482.
[3]HE Zhen,LI Zongjin.Influence of alkali on restrained shrinkage behavior of cement-based materials[J].Cement and Concrete Research,2005,35(3):457-463.
[4]THOMAS J J,ALLEN A J,JENNINGS H M.Structural changes to the calcium-silicate-hydrate gel phase of hydrated cement with age,drying,and resaturation[J].Journal of the American Ceramic Society,2008,91(10):3362-3369.
[5]PAGLIA C,WOMBACHER F,BHNI H.The influence of alkali-free and alkaline shotcrete accelerators within cement systems:I.Characterization of the setting behavior[J].Cement and Concrete Research,2001,31(6):913-918.
[6]POURCHET S,REGNAUD L,PEREZ J P,et al.Early C3A hydration in the presence of different kinds of calcium sulfate[J].Cement and Concrete Research,2009,39(11):989-996.
[7]MOTA B,MATSCHEI T,SCRIVENER K.The influence of sodium salts and gypsum on alite hydration[J].Cement and Concrete Research,2015,75:53-65.
[8]陈美祝.水泥基材料组分对早期水化及收缩开裂影响的研究[D].武汉:武汉大学,2004.CHEN Meizhu.Study on the effect of cement based material composition on early hydration and shrinkage cracking[D].Wuhan:Wuhan University,2004.(in Chinese)
[9]KRSTULOVIC'R,DABIC'P.A conceptual model of the cement hydration process[J].Cement and Concrete Research,2000,30(5):693-698.
[10]DOVE P M.The dissolution kinetics of quartz in aqueous mixed cation solutions[J].Geochimica et Cosmochimica Acta,1999,63(22):3715-3727.
[11]RICHARDSON I G.The nature of C-S-H in hardened cements[J].Cement and Concrete Research,1999,29(8):1131-1147.
[12]RICHARDSON I G.Tobermorite/jennite-and tobermorite/calcium hydroxide-based models for the structure of C-S-H:Applicability to hardened pastes of tricalcium silicate,β-dicalcium silicate,Portland cement,and blends of Portland cement with blast-furnace slag,metakaolin,or silica fume[J].Cement and Concrete Research,2004,34(9):1733-1777.
[13]GARCIA LODEIRO I,FERNNDEZ-JIMENEZ A,PALOMO A,et al.Effect on fresh C-S-H gels of the simultaneous addition of alkali and aluminium[J].Cement and Concrete Research,2010,40(1):27-32.
[14]JOHANSSON K,LARSSON C,ANTZUTKIN O N,et al.Kinetics of the hydration reactions in the cement paste with mechanochemically modified cement 29Si magic-angle-spinning NMR study[J].Cement and Concrete Research,1999,29(10):1575-1581.
[15]BU Y,WEISS J.The influence of alkali content on the electrical resistivity and transport properties of cementitious materials[J].Cement and Concrete Composites,2014,51:49-58.
[16]SAKAI K,HANMAZAKI K.Properties of granulated blastfurnace slag cement concrete[C]∥Proceedings of 4th International Conference on Fly-Ash,Silica Fume,Slag and Natural Pozzolana in Concrete.Istanbul:American Concrete Institute,1992:1367-1383.
[17]王磊.C-S-H及其工程特性研究[D].武汉:武汉大学,2012.WANG Lei.Study on C-S-H and its engineering characteristics[D].Wuhan:Wuhan University,2012.(in Chinese)
[18]PAUL G,BOCCALERI E,BUZZI L,et al.Friedel's salt formation in sulfoaluminate cements:A combined XRD and 27Al MAS NMR study[J].Cement and Concrete Research,2015,67:93-102.
[19]何真,李洋,蔡新华,等.Na+和K+对水泥基材料早期收缩性能的影响[J].水利学报,2016,47(11):1345-1351.HE Zhen,LI Yang,CAI Xinhua,et al.Effects of Na+and K+on the early shrinkage of cement-based materials[J].Journal of Hydraulic Engineering,2016,47(11):1345-1351.(in Chinese)
[20]PAGLIA C,WOMBACHER F,BHNI H.The influence of alkali-free and alkaline shotcrete accelerators within cement systems:Influence of the temperature on the sulfate attack mechanisms and damage[J].Cement and Concrete Research,2003,33(3):387-395.
1)文中涉及的组成、比值等除特别说明外均为质量分数或质量比.
[2]ODLER I,WONNEMANN R.Effect of alkalies on Portland cement hydration:I.Alkali oxides incorporated into the crystalline lattice of clinker minerals[J].Cement and Concrete Research,1983,13(4):477-482.
[3]HE Zhen,LI Zongjin.Influence of alkali on restrained shrinkage behavior of cement-based materials[J].Cement and Concrete Research,2005,35(3):457-463.
[4]THOMAS J J,ALLEN A J,JENNINGS H M.Structural changes to the calcium-silicate-hydrate gel phase of hydrated cement with age,drying,and resaturation[J].Journal of the American Ceramic Society,2008,91(10):3362-3369.
[5]PAGLIA C,WOMBACHER F,BHNI H.The influence of alkali-free and alkaline shotcrete accelerators within cement systems:I.Characterization of the setting behavior[J].Cement and Concrete Research,2001,31(6):913-918.
[6]POURCHET S,REGNAUD L,PEREZ J P,et al.Early C3A hydration in the presence of different kinds of calcium sulfate[J].Cement and Concrete Research,2009,39(11):989-996.
[7]MOTA B,MATSCHEI T,SCRIVENER K.The influence of sodium salts and gypsum on alite hydration[J].Cement and Concrete Research,2015,75:53-65.
[8]陈美祝.水泥基材料组分对早期水化及收缩开裂影响的研究[D].武汉:武汉大学,2004.CHEN Meizhu.Study on the effect of cement based material composition on early hydration and shrinkage cracking[D].Wuhan:Wuhan University,2004.(in Chinese)
[9]KRSTULOVIC'R,DABIC'P.A conceptual model of the cement hydration process[J].Cement and Concrete Research,2000,30(5):693-698.
[10]DOVE P M.The dissolution kinetics of quartz in aqueous mixed cation solutions[J].Geochimica et Cosmochimica Acta,1999,63(22):3715-3727.
[11]RICHARDSON I G.The nature of C-S-H in hardened cements[J].Cement and Concrete Research,1999,29(8):1131-1147.
[12]RICHARDSON I G.Tobermorite/jennite-and tobermorite/calcium hydroxide-based models for the structure of C-S-H:Applicability to hardened pastes of tricalcium silicate,β-dicalcium silicate,Portland cement,and blends of Portland cement with blast-furnace slag,metakaolin,or silica fume[J].Cement and Concrete Research,2004,34(9):1733-1777.
[13]GARCIA LODEIRO I,FERNNDEZ-JIMENEZ A,PALOMO A,et al.Effect on fresh C-S-H gels of the simultaneous addition of alkali and aluminium[J].Cement and Concrete Research,2010,40(1):27-32.
[14]JOHANSSON K,LARSSON C,ANTZUTKIN O N,et al.Kinetics of the hydration reactions in the cement paste with mechanochemically modified cement 29Si magic-angle-spinning NMR study[J].Cement and Concrete Research,1999,29(10):1575-1581.
[15]BU Y,WEISS J.The influence of alkali content on the electrical resistivity and transport properties of cementitious materials[J].Cement and Concrete Composites,2014,51:49-58.
[16]SAKAI K,HANMAZAKI K.Properties of granulated blastfurnace slag cement concrete[C]∥Proceedings of 4th International Conference on Fly-Ash,Silica Fume,Slag and Natural Pozzolana in Concrete.Istanbul:American Concrete Institute,1992:1367-1383.
[17]王磊.C-S-H及其工程特性研究[D].武汉:武汉大学,2012.WANG Lei.Study on C-S-H and its engineering characteristics[D].Wuhan:Wuhan University,2012.(in Chinese)
[18]PAUL G,BOCCALERI E,BUZZI L,et al.Friedel's salt formation in sulfoaluminate cements:A combined XRD and 27Al MAS NMR study[J].Cement and Concrete Research,2015,67:93-102.
[19]何真,李洋,蔡新华,等.Na+和K+对水泥基材料早期收缩性能的影响[J].水利学报,2016,47(11):1345-1351.HE Zhen,LI Yang,CAI Xinhua,et al.Effects of Na+and K+on the early shrinkage of cement-based materials[J].Journal of Hydraulic Engineering,2016,47(11):1345-1351.(in Chinese)
[20]PAGLIA C,WOMBACHER F,BHNI H.The influence of alkali-free and alkaline shotcrete accelerators within cement systems:Influence of the temperature on the sulfate attack mechanisms and damage[J].Cement and Concrete Research,2003,33(3):387-395.
1)文中涉及的组成、比值等除特别说明外均为质量分数或质量比.