煅烧煤矸石对硅酸盐水泥胶砂力学性能及微观结构的影响
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摘要
通过水泥胶砂力学强度测试,并结合压汞仪、X射线衍射、热重和扫描电镜测试,研究煅烧煤矸石掺量对水泥胶砂力学性能和水化产物微观结构的影响。力学性能测试结果表明:相同养护龄期下,水泥胶砂的抗压和抗折强度都先随煅烧煤矸石取代量增大而增加,取代量为15%时水泥胶砂的力学强度达到最大值;相同取代量下,水泥胶砂养护龄期越长,煅烧煤矸石对水泥胶砂力学性能的提升效果越显著。机理研究表明:煅烧煤矸石中主要组分为偏高岭土,其具有较强的火山灰效应。水泥水化初期,偏高岭土具有异相成核效应,可加速水泥的初期水化;水化后期,偏高岭土能与水泥水化产物氢氧化钙进一步发生水化反应,生成更多的水化硅酸钙凝胶,不仅降低了水化产物氢氧化钙对水泥胶砂的不利影响,而且提高了水泥胶砂的密实性,降低了水泥胶砂孔隙率并减少了有害孔比例,从而优化了水泥胶砂的孔径结构,使其力学性能得到强化。
The effect of Calcined Coal Gangue (CCG) dosage on the mechanical property and microstructure of hydrated Portland cement mortar was investigated by mechanical strength measurement as well as Mercury Injection Apparatus (MIP),X-Ray Powder Diffraction (XRD),Thermogravimetry (TG) and Scanning Electron Microscope (SEM) measurements. The results show that the compressive strength and flexural strength of cement mortar under the same curing age both increased with the increase of CCG replacement level and reached the maximum at 15% CCG replacement level; Meanwhile,the mechanical strength of cement mortar with the same CCG replacement level could be improved more significantly with the extension of curing age. The mechanism studies show that CCG is mainly comprised of metakaolin,which has strong pozzolanic activity. At the early curing age,the hydration of cement is improved by metakaolin due to its active heterogeneous nucleation effect; at the late curing age,metakaolin can react with the hydrated product of cement,calcium hydroxide,to generate more hydrated calcium silicate gel,which not only mitigate the detrimental effect of hydrating product calcium hydroxide on cement mortar,but also increase the compactibility of cement mortar and reduce the porosity and harmful pore ratio,consequently optimize the pore structure of cement mortar and enhance its mechanical property.
The effect of Calcined Coal Gangue (CCG) dosage on the mechanical property and microstructure of hydrated Portland cement mortar was investigated by mechanical strength measurement as well as Mercury Injection Apparatus (MIP),X-Ray Powder Diffraction (XRD),Thermogravimetry (TG) and Scanning Electron Microscope (SEM) measurements. The results show that the compressive strength and flexural strength of cement mortar under the same curing age both increased with the increase of CCG replacement level and reached the maximum at 15% CCG replacement level; Meanwhile,the mechanical strength of cement mortar with the same CCG replacement level could be improved more significantly with the extension of curing age. The mechanism studies show that CCG is mainly comprised of metakaolin,which has strong pozzolanic activity. At the early curing age,the hydration of cement is improved by metakaolin due to its active heterogeneous nucleation effect; at the late curing age,metakaolin can react with the hydrated product of cement,calcium hydroxide,to generate more hydrated calcium silicate gel,which not only mitigate the detrimental effect of hydrating product calcium hydroxide on cement mortar,but also increase the compactibility of cement mortar and reduce the porosity and harmful pore ratio,consequently optimize the pore structure of cement mortar and enhance its mechanical property.
引文
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[7]Mermerdas K,Gesoglu M,Guneyisi E,et al.Strength development of concretes incorporated with metakaolin and different types of calcined kaolins[J].Construction Building Materials,2012,37:766-774.
[8]Arikan M,Sobolev K,Ertun T,et al.Properties of blended cements with thermally activated kaolin[J].Construction Building Materials,2009,23:62-70.
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[10]Kakali G,Perraki T,Tsivillis S,et al.Thermal treatment of kaolin:the effect of mineralogy on the pozzolanic activity[J].Applied Clay Science,2001,20:73-80.
[11]曹永丹,李彦鑫,张金山,等.细度和煅烧温度对煤矸石火山灰活性及微观结构的影响[J].硅酸盐学报,2017,45(8):1153-1158.
[12]吴中伟,廉慧珍.高性能混凝土[M].北京:中国铁道出版社,1999:84-86.
[13]Chen Y M,Zhou S X,Zhang W S.Effect of coal gangue with different kaolin contents on compressive strength and pore size of blended cement paste[J].Journal of Wuhan University of Technology Science Edition,2008,23:12-15.
[14]Khatib J M,Clay R M.Absorption characteristics of metakaolin concrete[J].Cement and Concrete Research,2004,34:19-29.
[15]Larbi J A,Bijen J M.Influence of pozzolans on the Portland cement paste-aggregate interface in relation to diffusion of ions and water absorption in concrete[J].Cement and Concrete Research,1992,22:551-562.
[16]李福海,张桂斌,周鸿屹,等.高活性偏高岭土及粉煤灰对碱骨料反应的抑制作用[J].建筑材料学报,2017,20(6):876-880.
[17]Murat M.Hydration reaction and hardening of calcined clays and related minerals.I.Preliminary investigation on metakaolinite[J].Cement and Concrete Research,1983,13:259-266.
[18]Khatib J M,Wild S.Sulfate resistance of metakaolin mortar[J].Cement and Concrete Research,1998,28:83
[19]莫宗云,高小建.偏高岭土改性混凝土的耐久性研究进展[J].材料导报.2017,31(8):115-119.
[20]Al-akhras N M.Durability of metakaolin to sulfate attack[J].Cement and Concrete Research,2006,36:1727-1734.
[21]Vance K,Aguayo M,Oey T,et al.Hydration and strength development in ternary portland cement blends containing limestone and fly ash or metakaolin[J].Cement and Concrete Composites,2013,39:93-103.
[22]Bohac M,Palou M,Novotny R,et al.Investigation on early hydration of ternary portland cement-blast-furnace slag-metakaolin blends[J].Construction Building Materials,2014,64:333-341.
[23]乔春雨,倪文,王长龙.较大偏高岭土掺量下偏高岭土-水泥硬化浆体性能与微观结构[J].建筑材料学报,2015,18(3):393-399.
[2]Siddique R,Klaus J.Influence of metakaolin on the properties of mortar and concrete:a review[J].Applied Clay Science,2009,43:392-400.
[3]Tironi A,Trezza M A,Scian A N,et al.Thermal analysis to assess pozzolanic activity of calcined kaolinitic clays[J].J Therm.Anal Calorim,2014,117:547-556.
[4]Gimenez-garcia R,Mencia R,Rubio V,et al.The transformation of coal-mining waste minerals in the pozzolanic reactions of cements[J].Minerals,2016,6:64-75.
[5]Fernández R,Martirena F,Scrivener K L.The origin of the pozzolanic activity of calcined clay minerals:a comparison between kaolinite,illite and montmorillonite[J].Cement and Concrete Research,2011,41:113-122.
[6]Alujas A,Fernández R,Quintana R,et al.Pozzolanic reactivity of low grade kaolinitic clays:Influence of calcination temperature and impact of calcination products on OPC hydration[J].Applied Clay Science,2015,108:94-101.
[7]Mermerdas K,Gesoglu M,Guneyisi E,et al.Strength development of concretes incorporated with metakaolin and different types of calcined kaolins[J].Construction Building Materials,2012,37:766-774.
[8]Arikan M,Sobolev K,Ertun T,et al.Properties of blended cements with thermally activated kaolin[J].Construction Building Materials,2009,23:62-70.
[9]Taylor-lange S,Lamon E,Riding K,et al.Calcined kaolinite-bentonite clay blends as supplementary cementitious materials[J].Applied Clay Science,2015,108:84-93.
[10]Kakali G,Perraki T,Tsivillis S,et al.Thermal treatment of kaolin:the effect of mineralogy on the pozzolanic activity[J].Applied Clay Science,2001,20:73-80.
[11]曹永丹,李彦鑫,张金山,等.细度和煅烧温度对煤矸石火山灰活性及微观结构的影响[J].硅酸盐学报,2017,45(8):1153-1158.
[12]吴中伟,廉慧珍.高性能混凝土[M].北京:中国铁道出版社,1999:84-86.
[13]Chen Y M,Zhou S X,Zhang W S.Effect of coal gangue with different kaolin contents on compressive strength and pore size of blended cement paste[J].Journal of Wuhan University of Technology Science Edition,2008,23:12-15.
[14]Khatib J M,Clay R M.Absorption characteristics of metakaolin concrete[J].Cement and Concrete Research,2004,34:19-29.
[15]Larbi J A,Bijen J M.Influence of pozzolans on the Portland cement paste-aggregate interface in relation to diffusion of ions and water absorption in concrete[J].Cement and Concrete Research,1992,22:551-562.
[16]李福海,张桂斌,周鸿屹,等.高活性偏高岭土及粉煤灰对碱骨料反应的抑制作用[J].建筑材料学报,2017,20(6):876-880.
[17]Murat M.Hydration reaction and hardening of calcined clays and related minerals.I.Preliminary investigation on metakaolinite[J].Cement and Concrete Research,1983,13:259-266.
[18]Khatib J M,Wild S.Sulfate resistance of metakaolin mortar[J].Cement and Concrete Research,1998,28:83
[19]莫宗云,高小建.偏高岭土改性混凝土的耐久性研究进展[J].材料导报.2017,31(8):115-119.
[20]Al-akhras N M.Durability of metakaolin to sulfate attack[J].Cement and Concrete Research,2006,36:1727-1734.
[21]Vance K,Aguayo M,Oey T,et al.Hydration and strength development in ternary portland cement blends containing limestone and fly ash or metakaolin[J].Cement and Concrete Composites,2013,39:93-103.
[22]Bohac M,Palou M,Novotny R,et al.Investigation on early hydration of ternary portland cement-blast-furnace slag-metakaolin blends[J].Construction Building Materials,2014,64:333-341.
[23]乔春雨,倪文,王长龙.较大偏高岭土掺量下偏高岭土-水泥硬化浆体性能与微观结构[J].建筑材料学报,2015,18(3):393-399.
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