30 Hydration characteristics of tricalcium aluminate phase in mixes containing β-hemihydate and pho
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大庆石油地质与开发Petroleum Geology & Oilfield Development in Daqing2024 年 2 月第 43 卷 第 1 期Feb. ,2024Vol. 43 No. 1DOI :10.19597/J.ISSN.1000-3754.202305001古龙页岩油高温高压注CO 2驱动用效果李斌会1,2,3 邓森1,2,3 张江1,2,3 曹胜1,2,3郭天娇1,2,3 徐全1,2,3 霍迎冬1,2(1.多资源协同陆相页岩油绿色开采全国重点实验室,黑龙江 大庆163712;2.中国石油大庆油田有限责任公司勘探开发研究院,黑龙江 大庆163712;3.黑龙江省油层物理与渗流力学重点实验室,黑龙江 大庆163712)摘要: 为了明确古龙页岩油高温高压注CO 2驱动用效果,首先根据页岩压汞和氮气吸附实验结果,给出页岩T 2值与孔喉半径转换系数,根据饱和页岩的T 2谱特征,将页岩孔隙分为小孔、中大孔和页理缝;然后通过计算页岩油采出程度,考察吞吐周期、闷井时间、裂缝对吞吐驱油效果的影响,并且分析吞吐后岩心孔隙结构的改变程度;最后对比页岩油CO 2吞吐和CO 2驱替的驱油效果,并给出最优的驱油方式。
结果表明:吞吐动用幅度最大的是中大孔和页理缝中的页岩油,小孔中的页岩油采出程度最低,增加闷井时间,页岩油采出程度仅提高0.81百分点,压裂可以使小孔中的页岩油采出程度提高11.33百分点,使小孔中的页岩油得到有效动用;吞吐比驱替可以使页岩油采出程度提高30.98百分点,并且可以动用干岩样中的页岩油,效果优于驱替;驱吞结合驱油方式比只进行吞吐可以使页岩油采出程度提高12.88百分点以上,并且可以大幅度提高小孔中页岩油的采出程度;吞吐后岩心孔隙结构发生明显变化,页岩砂砾含量不同是导致页岩吞吐前后孔隙结构变化差异大的重要原因。
研究成果可为古龙页岩油矿场实践提供重要的基础参数。
关键词:古龙页岩油;孔隙结构;CO 2驱替;CO 2吞吐;高温高压;核磁共振中图分类号:TE357 文献标识码:A 文章编号:1000-3754(2024)01-0042-10Producing effect of CO 2 displacement injection at high temperature and high pressure for Gulong shale oilLI Binhui 1,2,3,DENG Sen 1,2,3,ZHANG Jiang 1,2,3,CAO Sheng 1,2,3,GUO Tianjiao 1,2,3,XU Quan 1,2,3,HUO Yingdong 1,2(1.National Key Laboratory for Multi⁃resource Collaborated Green Development of Continental Shale Oil ,Daqing 163712,China ;2.Exploration and Development Research Institute of Daqing Oilfield Co.,Ltd.,Daqing 163712,China ;3.Heilongjiang Provincial Key Laboratory of Reservoir Physics & FluidMechanics in Porous Medium ,Daqing 163712,China )Abstract :In order to clarify the effectiveness of CO 2 injection at high temperature and high pressure for Gulong shale oil , the conversion coefficient between shale T 2 value and pore throat radius is firstly given based on the re⁃sults of shale mercury injection and nitrogen adsorption experiments. Shale pores are divided into small pores , medi⁃um -large pores and lamellation fractures based on T 2 spectrum characteristics of saturated shale. Then , through cal⁃收稿日期:2023-05-04 改回日期:2023-08-08基金项目:国家科技重大专项“大庆古龙页岩油勘探开发理论与关键技术研究”(2021ZZ10)。
1HYDRATION1.1IntroductionHydration is defined as the chemical absorption of water into a substance,a process by which heat is generated(hydration heat).The setting of concrete—which can be considered as a transition from liquid to solid phase—is the most relevant example for the hydration process in the engineering world.The effects of the hydration process can be separated into a thermal part and a mechanical part. The implementation of hydration models in FLAC3D follows this separation,as the hydration heat generation and heat transfer are dealt with in separate thermal models,material hardening and strength development are implemented as constitutive models.The coupling parameter between both modules is the hydration grade a,which is defined as the ratio of the accumulated hydration heat at time t to the ultimate hydration heat generated until completion.α(t)=Q(t)Q∞(1.1)The time-dependent evolution of the hydration grade is mainly governed by the temperature bound-ary conditions.Lower temperatures lead to a longer process with lower hydration heat generation, whereas higher temperatures lead to a shorter process with higher hydration heat generation.To have a unique reference value,the concrete age t e,which is the equivalent concrete age at a reference temperature(of20◦C)and is calculated as a function of thermal time t and concrete temperature T,is introduced.t e= tt=0eE AR·1293−1T·dt(1.2)where R is the universal gas constant(8.314J/K/mol)and E A is the activation energy[J/mol].In FLAC3D,two different thermal hydration models are implemented:a thermal hydration model for German concrete,th hyd concrete1;and an empirical,more general hydration model,th hyd. During the hydration process,the values of elastic material parameters can vary over several orders of magnitude.Accordingly,the gridpoint masses have to be adjusted for numerical stability,in small strain mode as well as in large strain mode.The frequency of the update can be set by the user with the FLAC3D command SET geom rep value.1.2Thermal Hydration Model for German Concrete(th hyd concrete1)In the hydration model for German concrete,th hyd concrete1(Onken and Rostásy,1995),the hydration gradeαis a function of the concrete age t e.α(t e)=e−ln1+t e t1b(1.3)where b and t1are constants.The hydration heat rate q depends on the gradient of the hydration grade.q(t)=Q maxCe ·C· αt(1.4)where C is the cement concentration in[kg/m3],and Q maxCe (in[J/kg])is the maximum amount ofheat that can be generated,and is estimated to beQ max Ce = T·c c·ρC(1.5)where c c is the specific heat of the material[J/kg/K].The heat transfer is assumed to be isotropic with constant values of specific heat,thermal conduc-tivity and coefficient of thermal expansion.1.3General Hydration Model (th hyd )In the more general empirical hydration law th hyd ,the activation energy E A ,the heat capacity c P ,and the thermal conductivity λare functions of temperature or temperature and hydration grade,respectively.The hydration grade is again a function of the effective concrete age t e .α(t e )=e− ln 1+t et1b(1.6)The activation energy E A is a function of temperature T .E A (T )=E A,1+E A,2−E A,11+eT −T 0,EAdT(1.7)The heat capacity c p and the thermal conductivity λdepend on the temperature T and the hydration grade α.c p (α,T )=c p,1+dc p,a ·α+T −T T 1,c p·dc p,T λ(α,T )=(λ1+dλa ·α)·(1+dλT ·T )(1.8)The hydration heat source strength is limited to a temperature range.q(T )=Q max Ce ·C ·α t,T ≤T max,q 0,T >T max,q(1.9)1.4A Modified Drucker-Prager Model for HydrationThe implementation of hydration in FLAC3D is a Drucker-Prager constitutive model with hydration gradeαdepending on elastic and strength properties(Hinze1987).During the hydration process, the actual Young’s modulus E is a function of the hydration gradeα.E(α)=E cte·α−α01−α0a(1.10)where E cte is the Young’s modulus after complete hydration and a is a specific parameter for cement (usually of the order of0.5–0.7).The actual uniaxial compressive strengthσc,and uniaxial tensile strengthσt also depend on the hydration grade.σc=0.85·f ctec·α−α01−α03/2σt=f cte·α−α01−α0(1.11)where f cte is the uniaxial strength[MPa]after completion of the hydration process;α0is a specific parameter for cement(0.17–0.38);and c is a heat capacity factor(0.6–1.0).The yield criterion in the Drucker-Prager constitutive model(see Section2.5.1in Theory and Background)is0=τ+q·σ−k(1.12) where q and k are material parameters,andτandσare stress invariants.q and k can be derived from the actual uniaxial compressive and tensile strengths,σc andσt.q=√3·(σD−σz)σD+σzk=2·σD·σz√3·σD+σz(1.13)1.5PropertiesTable1.1Thermal hydration model for German concrete—MODEL th hyd concrete1(1)e activate activation energy,E A(2)gas const universal gas constant,R(3)t1const material parameter,t1(4)b const material parameter,b(5)cement cement concentration,C(6)qmax maximum amount of generated heat,Q maxCe(7)spec heat specific heat,c p(8)conductivity conductivity,λread only(9)t concrete effective concrete age,t e(10)heat hydration heat rate,qTable1.2General thermal hydration model—MODEL th hyd(1)gas const universal gas constant,R(2)t1const material parameter,t1(3)b const material parameter,b(4)cement cement concentration,C(5)qmax maximum amount of generated heat,Q maxCe(6)E a1material parameter,E A,1(7)E a2material parameter,E A,2(8)T0EA material parameter,T0,EA(9)C p1material parameter,C p,1(10)dC pa material parameter,dC p,A(11)T1pc material parameter,T1,cp(12)dC pT material parameter,C p,T(13)lambda1material parameter,λ1(14)dLambda a material parameter,dλ1(15)dLambda T material parameter,dλT(16)T maxq material parameter,T max,qread only(17)t concrete effective concrete age,t e(18)heat hydration heat rate,q(19)e activate activation energy,E A(20)spec heat specific heat,c p(21)conductivity conductivity,λ(22)dT temperature change, TTable1.3Modified Drucker-Prager model for concrete—MODEL hydration(1)cte tension tensile strength forα=1,f cte(2)cte young Young‘s modulus forα=1,E cte(3)cte alpha material parameter,α0(4)a const material parameter,a(5)c const material parameter,c(6)tension tension limit strength,σt(7)compression compression limit,σD(8)Young Young’s modulus,E(9)dAlpha min minimum difference of(α−α0)min(10)qvol Drucker-Prager material parameter,q(11)kshear Drucker-Prager material parameter,k(12)qdil Drucker-Prager material parameter,q1.6Example Problems for the Hydration Model1.6.1Concrete Inclusion in an Elastic MediumThis example consists of a concrete inclusion inside an elastic and thermal isotropic material.The model has a size of10m×1m×10m and isfixed in the y-direction(Figure1.1).Roller boundary conditions are applied at the model boundaries.The material properties are listed in Table1.4(elastic frame)and Table1.5(concrete inclusion).The model was run for a thermal time of approximately250days.Figures1.2to1.6show the evolution of various parameters during the hydration process(gridpoint temperatures atfive points(Figure1.2),hydration grade(Figure1.3),tensile and compressive strength(Figure1.4),elastic parameters(Figure1.5)and the generated hydration heat(Figure1.6)).Figure1.1FLAC3D model for the concrete inclusion testTable1.4Material properties for the elastic materialBulk modulus(K)1000MPaShear modulus(G)700MPaSpecific heat(C P)0.2J/kg/KThermal conductivity(k)20.0W/kg/KLinear thermal expansion coefficient(αt)10−4◦C−1Table1.5Material properties for the concrete materialMaximum amount of generated heat(Q maxCe )105J/kgCement concentration(C)330kg/m3Material parameter(b)−1.114Material parameter(t1)7.2×104[s]Universal gas constant(R)8.314J/molActivation energy(E A)33.5J/molSpecific heat(C P)0.2J/kg/KThermal conductivity(λ) 2.0W/m/KLinear thermal expansion coefficient(αt)10−5◦C−1Specific parameter for cement(α0)0.20Young’s modulus after complete hydration(E cte)1000MPaMaterial parameter(c)0.4Material parameter(a)0.6Minimum value for(α−α0)10−4Figure1.2Evolution of gridpoint temperatures for the concrete inclusion test as a function of the concrete ageFigure1.3Evolution of the hydration grade for the center zone of the con-the concrete agecrete inclusion as a function ofFigure1.5Evolution of the elastic parameters for the center zone of thefunction of the concrete ageconcrete inclusion as aExample1.1HYDRAT1.DAT;-----------------------------------------------------------------------;Concrete inclusion in an elastic,thermal isotropic medium;;-----------------------------------------------------------------------newtitleConcrete inclusion in an elastic,thermal isotropic mediumset echo onconfig thermal;gen zone brick size11111macro concrete=’ra x47z47’;willimodel elast th_isomodel hydrat th_hyd_concrete1concrete;prop dens2000bulk1e3shear0.7e3prop cond20.0thex1e-4spec_heat0.2prop thex1e-5cond 2.0concreteprop qmax1e5cement330b_const-1.114t1_const7.2e4concreteprop gas_const8.314e_activate33.5cte_alpha0.20cte_tension 2.0 concreteprop cte_bulk0.98e3cte_shear0.50e3c_const0.4a_const0.6 concreteprop dalpha_min1e-4cte_young1e3concreteini temp300fix temp300ra x-0.10.1fix temp300ra x10.911.1fix temp300ra z10.911.1fix temp300ra z-0.10.1fix x ra x-0.10.1fix x ra x10.911.1fix yfix z ra z-0.10.1fix z ra z10.911.1hist gp temp105hist gp temp205hist gp temp305hist gp temp405hist gp temp505hist gp temp205def hist_setuphzp=z_nearall(6.5,0.5,6.5)endhist_setupdef hyd_histh_alpha=z_prop(hzp,’alpha’)h_q=z_prop(hzp,’heat’)h_te=z_prop(hzp,’t_concrete’)h_tension=z_prop(hzp,’tension’)h_comp=z_prop(hzp,’compression’)h_young=z_prop(hzp,’young’)h_bulk=z_prop(hzp,’bulk’)h_shear=z_prop(hzp,’shear’)h_poiss=z_prop(hzp,’poisson’)endhist hyd_histhist h_alpha h_q h_tehist h_tension h_comphist h_young h_bulk h_shear h_poissset geom_rep500hist nstep100cyc13000save hyd_inclusion.savplot hist8vs10return1.6.2Concrete Wall on Elastic BaseplateThe numerical model(Figure1.7)used here is based on a model,which was used by Onken &Rostásy(1995)to compare numerical results and temperature measurements.It consists of a new concrete wall(10×1×40elements),footed on a baseplate of old concrete(10×1×5elements).Since the material parameters and the boundary conditions are not available from Onken&Rostásy(1995),the material parameters from Example1.1are used together with typical temperature boundary conditions.For the concrete wall,the thermal hydration model for German concrete(th hyd concrete1)and the modified Drucker-Prager with hydration(hydrat)are used.The baseplate is considered elastic and thermal isotropic.The model was under summer temperature conditions.The temperatures at the wall boundary are fixed to air temperature,at the baseplate to the initial ground temperature:Initial wall temperature,296KWall boundary temperaturefixed at293KInitial baseplate temperature,285KBaseplate boundary temperaturefixed at285KThe numerical results are displayed in Figures1.8to1.13.Shown are the temperature distribution inside the model after1and3days(Figures1.8and1.9),evolution of gridpoint temperatures (Figure1.10),evolution of the hydration grade(Figure1.11),evolution of the strength parameters (Figure1.12),evolution of the elastic parameters(Figure1.13),and evolution of the generated hydration heat.The results are qualitatively in good agreement with the results given by Onken& Rostásy(1995)(a more detailed comparison is not available due to the limited access to material parameter and boundary conditions).Figure1.7Model of the concrete wall on an elastic baseplateFigure1.8Temperature distribution after1day(concreteage)Figure1.12Evolution of the tensile and compressive strength as a functionconcrete ageof theFigure1.14Evolution of the generated hydration heat as a function of theconcrete ageExample1.2HYDRAT2.DAT;-----------------------------------------------------------------------;Concrete inclusion in an elastic,thermal isotropic medium;;-----------------------------------------------------------------------newtitleHydratation:Concrete wall on elastic base plate-summer temperature conditionsconfig thermal;gen zone brick p0=(-0.5,0.0,0.0)p1=(0.5,0.0,0.0)p2=(-0.5,1.0,0.0)& p3=(-0.5,0.0,10.0)size=10,5,20gen zone brick p0=(-2.5,0.0,-1.0)p1=(2.5,0.0,-1.0)p2=(-2.5,1.0,-1.0)& p3=(-2.5,0.0,0.0)size=20,5,5attach face ra z-0.010.01;group concrete range z0100group base_plate range z-1000model elast th_iso range group base_platemodel hydrat th_hyd_concrete1range group concreteprop dens2000bulk1e3shear.7e3prop cond20.thex1e-4spec_heat0.2prop cond 2.thex1e-5range group concreteprop qmax1e5cement330b_const-1.114t1_const7.2e4 range group concreteprop gas_const8.314e_activate33.5e3cte_alpha0.20cte_tension 2.0 range group concreteprop cte_bulk0.98e3cte_shear0.50e3c_const0.4a_const0.6 range group concreteprop dalpha_min1e-4cte_young1e3range group concreteini temp296fix temp293ra x-0.51,-0.49z0.0100fix temp293ra x0.49,0.51z0.0100fix temp293ra z9.9,10.1ini temp285range group base_platefix temp285ra z-1.01-0.99fix temp285ra x-10.0-0.49z-0.010.01fix temp285ra x0.4910.0z-0.010.01fix x y z ra z-0.9-1.1fix x ra x-2.6-2.4fix x ra x 2.4 2.6hist gp temp00.51hist gp temp00.52hist gp temp00.53hist gp temp00.54hist gp temp00.55def hist_setuphzp=z_near(0,0,5)endhist_setupdef hyd_histh_alpha=z_prop(hzp,’alpha’)h_q=z_prop(hzp,’heat’)h_te=z_prop(hzp,’t_concrete’)h_tension=z_prop(hzp,’tension’)h_comp=z_prop(hzp,’compression’) h_young=z_prop(hzp,’young’)h_bulk=z_prop(hzp,’bulk’)h_shear=z_prop(hzp,’shear’)h_poiss=z_prop(hzp,’poisson’)h_time=thtimeendhist hyd_histhist h_alpha h_q h_tehist h_tension h_comphist h_young h_bulk h_shear h_poisshist h_timeset geom_rep=500solve age86400save hyd_exp2_1d.savset age259200save hyd_exp2_3d.sav1.7ReferencesHinze,D.“Dissertation zum Thema:Zur Beurteilung des phsikalischen nicht-linearen Betonverhal-tens bei mehrachsigem Spannungszustand mit Hilfe differenzieller Stoffgesetze unter Anwendung der FEM,”Hochschule f˝u r Architektur und Bauwesen,Weimar(1987).Onken,P.&Rostásy,F.Wirksame Betonzugfestigkeit im Bauwerk bei fr˝uh einsetzendem Tem-peraturzwang.DafStb Heft449,Berlin:Beuth-Verlag(1995).。
药物分析实验典型问题1、鉴别检查在药物质量控制中旳意义及一般杂质检查旳重要项目是什么? What are thepurposes of drug identification and test? What are the usual items of drug tests?.2、比色比浊操作应遵循旳原则是什么? What are the standard operation procedures forthe clarity test?3、试计算葡萄糖重金属检查中原则铅溶液旳取用量。
How much of the lead standardsolution should be taken for the limit test for heavy metals in this experiment?4、古蔡氏试砷法中所加各试剂旳作用与操作注意点是什么? What precautions shouldbe taken for the limit test for arsenic(Appendix VIII J,method 1)? And what is the function for each of the test solutions added?5、根据样品取用量、杂质限量及原则砷溶液旳浓度,计算原则砷溶液旳取用量。
Figure outthe amount of the arsenic standard solution that should be taken for the limit test for arsenic(Appendix VIII J,method 1) (0.0001%) in this experiment with the specified quantity of 2.0 g of sample.6、炽灼残渣测定旳成败核心是什么?什么是恒重?What is the key step during thedetermination of residue on ignition? What does ‘ignite or dry to constant weight’mean?7、盐酸普鲁卡因旳鉴别原理是什么?What are the principles of the identification ofProcaine Hydrochloride.8、盐酸普鲁卡因注射液中为什么要检核对氨基苯甲酸?Why is the limit of4-aminobenzoic acid tested for Procaine Hydrochloride?9、薄层色谱法检查药物中有关物质旳措施一般有哪几种类型?本实验属于哪种?与其他措施有何异同点? How many kinds of the limit tests for related compounds are there?What are the differences between them? Which one is used for the limit test of 4-amino-benzoic acid in Procaine Hydrochloride Injection?10、醋酸氢化可旳松旳鉴别原理是什么?What are the principles of the identification ofhydrocortisone acetate?11、甾体激素中“其他甾体”检查旳意义和常用措施是什么?What are the commonly usedmethod for and the significance of the limit test for other steroids for the steroidal drugs?12、哪类甾体激素可与四氮唑蓝产生反映,是构造中旳何种基团参与了反映,反映式是什么?What kind of steroidal drugs can react with the alkaline tetrazolium blue TS?What is the chemical reaction equation?13、氯贝丁酯旳鉴别原理是什么?What are the principles of the identification ofclofibrate?14、氯贝丁酯中为什么要检核对氯酚?其措施及原理是什么?Why is the limit ofp-Chlorophenol tested for clofibrate? What kind of method is employed for the test and what is the principle?15、气相色谱法检查杂质有哪些措施,试比较多种措施旳特点?How many types ofmethods are there for the test of related compounds by the gas chromatography?What are the differences between them?16、抗生素类药物旳鉴别和检查有何特点?What are the characteristics for theidentification and tests of antibiotics?17、钠盐旳焰色反映应注意什么?What precautions should be taken during the flamereaction of sodium salts?18、本品吸取度检查旳意义是什么?What is the purpose of the light absorption tests forbenzylpenicillin sodium?19、药物晶型测定旳常用措施有哪些,各有什么特点?What are the commonly usedmethods for the test of polymorphism? And what are the characteristics of each of them?20、吸取系数测定措施与规定?What are the standard operation procedures for theestablishment of specific absorbance?21、写出异烟肼与溴酸钾旳滴定反映式和滴定度旳计算过程。
2013年5月戴群等.表面活性剂降压增注技术在江家店特低渗透油田的应用l l表面活性剂降压增注技术在江家店特低渗透油田的应用戴群1,王磊1,王长俊2,杨景辉1(1.中国石化胜利油田分公司采油工艺研究院,山东东营257000;2.中国石化胜利油田分公司临盘采油厂,山东临邑251500)[摘要]对双子表面活性剂的性能进行了室内研究,并在江家店油田进行了现场应用。
结果表明,该阳离子双子表面活性剂具有良好的表面活性,较好的耐温耐盐性能,能有效防止黏土膨胀,防止注入水中的油污黏附,提高水的渗流能力,其防膨率>90%,增溶能力33m L/m L,浓度为200m g/L时表/界面张力分别为26.94m N/m和0.06m N/m。
现场试验结果证明,该双子表面活性剂可有效降低束缚水及残余油的饱和度,实现减阻、降压及稳压注水。
[关键词]双子表面活性剂降压增注低渗透油田性能评价江家店油田位于惠民凹陷临南一夏口断裂带,断块含油面积为4.3km2,地质储量5.08M t,油层埋深在3200—3400m,纵向上油层多,层间差异大,平均渗透率仅为8.5X10~斗m2,属于典型的特低渗油藏…。
由于储层物性差、渗透率低、孔喉细微、渗流阻力大等内在因素,使得注水能量传导能力差,致使注水压力高,压力上升快,水井严重欠注,欠注率高达80%,制约了江家店特低渗油藏的注水开发。
针对特低渗透油田注水困难的情况,从2006年起先后实施12井次酸化增注措施,主要采用常规土酸酸化工艺,具有一定的效果,但均存在油压上升快、有效期短的问题。
由于未找到有效的增注治理措施,2008年后再未实施酸化增注措施,水井欠注日益严重。
常规酸化是注水井解堵增注的重要措施之一,它在油田长期的生产过程中发挥了重要作用。
但酸液中的盐酸、氢氟酸是强酸,反应快,作用距离短,酸化深度浅,有效期短。
针对这种情况笔者研究探索了新型的表面活性剂降压增注技术口‘4j,以解决该区块水井欠注严重问题,改善区块注水效果。
0引言在生物医学领域,体温是一个非常重要的生理参数,患者体温是医生判断患者生理状态的重要依据[1]。
医疗器械作为医学诊疗技术发展的主要推动力,是医院诊疗技术的重要支柱之一。
一直以来,水银体温计因性能稳定、价格低廉、计数准确等优点被临床认可并广泛用于医疗机构中患者临床体温的测量[2]。
但是水银体温计存在易碎、易发生水银泄漏等危险因素[3],严重危害环境及患者健康。
2017年8月,国家环境保护部联合国家多部门发布了2017年第38号公告《关于汞的水俣公约》(以下简称《汞公约》)生效公告,公布《汞公约》将自2017年8月16日起对我国正式生效,自2026年1月1日起,禁止生产含汞体温计和含汞血压计[4]。
因此,鉴于《汞公约》、环保等要求和因素,医院中水银体温计的淘汰势在必行。
基于人体生理学原理,最准确的体温测量方式国内医用体温计临床使用计量质控现状分析刘相花,徐力*,颜乐先,尹军,黄靖,周德强(陆军军医大学大坪医院医学工程科,重庆400042)[摘要]阐述了国内外医用无汞体温计的临床应用现状,介绍了玻璃体温计、电子体温计、变色体温计3种类型的国内医用体温计计量质控现状,分析了国内医用体温计存在临床需求量大、不同类别体温计测量结果差异性较大、缺少规范性,水银体温计的替换缺乏有效的实施方案及无汞体温计与临床使用过程质量控制标准体系不完善的问题。
指出了应制订有效的水银体温计可行性替换方案,进行区域化的体温计计量质控体系建设及深入无汞体温计临床使用过程研究,建立无汞体温计的使用操作规范,对《关于汞的水俣公约》的实施、水银体温计替换方案的制订具有重要的参考价值。
[关键词]医用体温计;汞公约;计量质控;无汞体温计;水银体温计[中国图书资料分类号]R318.6;TH789[文献标志码]A[文章编号]1003-8868(2020)01-0074-05 DOI:10.19745/j.1003-8868.2020018Analysis of current status of clinical measurement quality control ofmedical thermometers in ChinaLIU Xiang-hua,XU Li*,YAN Le-xian,YIN Jun,HUANG Jing,ZHOU De-qiang(Department of Medical Engineering,Daping Hospital of Army Medical University,Chongqing400042,China) Abstract The present situation of clinical application of medical mercury-free thermometers was described in foreign countries and China,and the quality control situation of three types of medical thermometers in China was introduced including glass thermometer,electronic thermometer and color-changing thermometer.The problems of medical thermometers in China were analyzed including large demand for clinical application,big difference in measurement results by types of thermometers,lack of standardization and effective implementation of replacing mercury thermometers,imperfect clinical quality control system of mercury-free thermometer and etc.It was pointed out that an effective feasible replacement scheme for mercury thermometers should be developed,the regional quality control system for thermometers should be built,the clinical application process of mercury-free thermometers should be studied,and the operation specifications for mercury-free thermometers should be established,which had important reference values for the implementation of Minamata Convention on Mercury and the formulation of replacement scheme for mercury thermometers.[Chinese Medical Equipment Journal, 2020,41(1):74-77,108]Key words medical thermometer;minamata convention;measurement quality control;mercury-free thermometer;mercury thermometer基金项目:2019年重庆市技术创新与应用发展专项(cstc2019jscx-msxmX0272)作者简介:刘相花(1983—),女,硕士,工程师,主要从事医疗器械应用质量管理方面的研究工作,E-mail:lan-cao_ly@。
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of partPart Tolerancepart weightparting linepin-point gateplastic partsplasticizationplate-like partspost mold isobaric coolingPressure at the entrancepressure controlPressure differencePressure |DistributonPressure Historyprssure-volume-temperature relationship PVT process cycleprocessing parametersprojected arearace trackRectangular runnerreinforcedreinforcement contentreinforcing ribrelaxationResidual stressReynolds numberRheologyRibRib geometryring gaterunnerrunner balancerunner cross sectionrunner diameterrunner dimensions (sizes)runner lengthrunner platerunner pullerScrew rotation speedrunner stripper platerunner systemrunner system layoutsrunnerless mouldsealing pressuresemi-crystalline polymerssemi-crystallineserrationsSetted injection pressure profile shaftShearshear rateshear stressShear Stress Distributionshear-thinningshort shotshort term loadshot capacityshouldered ejector pinshrinkage rateshrinkageshrindage &warpage simulation shrinkage stressShrindage voidsslide coreside guide pinSilver streaksSingle vs.multiple gatesskin layersnap-fit Jointssolidification layerspruesprue bush / sprue busingsprue pullersprue puller,conical headedstate equationstep changeswitch-over positionthermal degradation temperature Amorphous polymersdegree of crystallinity degree of moisture absorption hygroscopic polymersBulk temperatureCA(Cellulosics)crystalline polymersGF (glass-fiber)glsaay stateLDPE (Low Density Polyethylene) mechanical performancecpolymerThermophysical Properties thermoplasticsHIPS(high impact polystyrene) viscosityviscous heatingViscoelastic behaviorcross-linkcrystallineswellSpecific HeatSpecific VolumeCalorimertric properties temperature gradientheat fluxHeat of CrystallizationHeat of Fusionheat of phase transitionHigh elastics satatehot spotTransition TemperatureMelting Temperature/TMlattice通用翻译满足或高于消费者期望的产品综合质量保证质量前提下允许尺寸的波动范围表明制品,不良或不合格内容的小说明表明制品,物品,地点等特性或作用的小说明必要与不必要的物品分开处理物品分门别类,按规定摆放并标识去除赃污防止再次发生将整理、整顿清扫制度化、标准化人人按照规定和制度行事,养成良好习惯自身安全,他人安全和设备安全上一工序的产品质量不符合本工序质量要求在制品表面因手或其它物体摩擦形成的影响制品外观质量的现象由于重力或压力引起接触面的痕迹,可影响外观美观起固定作用的栓件通过加热使物料熔化在注射到模具内形成期望的制品对设备参数控制的简易操作平台显示设备必要信息的屏幕防止事故发生,增大安全系数的保护装置门注射成型机组成部件,支撑并协助注射的金属平台起旋转计量作用的螺纹状部件.是成型机的核心机械件树脂预塑的炮膛状部件,和螺杆配合俎件质量要求较高围绕在料膛周围,起迅速并均匀加热作用的片状加热器连接注射成型机料筒与模具浇口套接触的像针头状的组件可固定模具在成型机上的铁板,是成型机的一部分成型机曲臂连接板,使模具固定在成型机上做开合模运动的动模板连接到模具上控制模具顶杆顶出或回退作用的连接杆只能手动单一步骤状态操作可半自动状态操作根据设置的程序在全自动状态动作一般用PE料做射出动作来清除或淡化料膛内物料或颜色在料杯树脂不足在传感器监控下吸取储备树脂的成型辅助设备在全自动生产状态下对产品质量和数量控制的页面模板动作状态控制页面顶出动作状态控制画面材料加热控制画面注射过程中对速度控制的画面注射过程中注射压力控制画面注射后保持设定压力提高制品质量的控制画面计量尺寸和相关参数控制画面设备动作异常或监控报警预览成型机模板打开的最大尺寸成型过程中为保证动,定模相互紧密配合而需施加的在模具上的力模板控制系统,注塑机上系统的一部分计算机通过检测、处理信息并重新输入计算机进行控制相关参数将侧型心抽至不防碍制品脱落的滑块滑动的距离从模内的成型塑件中,抽拔出侧型心所需要的力生产每个制品的时间或是单位时间内生产制品的个数液压动力注射机上的压力系统由于一次注射压力不足或速度偏低引起的浇不足现象材料水份超标,结构不良引起的表面气泡等不良现象热熔体在收缩情况下表面会形成凸凹状现象的统称制品厚度不均匀或分子排列不同引起的不均匀收缩两股或多股熔体结合位置形成的线状痕迹一种有明亮痕迹的注塑成型缺陷,一般为线状少为带状低温区域的熔接,多见于冲填结束,不同塑料熔前交汇造成又称包气,熔体流动将气体堵住或包住不能及时排出填充时模具内部气体不能迅速排出产生压缩高温,导致制品局部变色注射成型过程中因高温或树脂分解等原因引起的黑色不良现象树脂在模具腔内流动时由于层流因素引起的外观不良现象因高温引起的成型缺陷的一种制品本身颜色有其他杂质颜色混入形成的不良现象成型缺陷(因树脂性质发生变化引起的脆化或者破裂)高聚物在恒定温度和应力下,长度随时间延长而逐步深长的现象熔体内部压力差引起高压部份向低压部分推移现象,可产生层次感同一树脂或不同树脂发生层流后产生的 现象局部温度差由大分子链排列引起的具有方向特性的收缩生产出的制品在不同的环境下都会产生尺寸的变化制品尺寸的稳定性和一致性单位体积的质量有多种原因引起的变形现象,如收缩翘曲,配向翘曲等产品在内应力或外力的作用下产生的尺寸变化以及形状变化熔体的某一部份发生停止流动或极缓慢流动的现象发生在垂直于熔体流动方向上的收缩热力的作用下,塑料可以发生变形的温度保压后制品在模具内部成型完毕脱离模具的现象方便成型制品脱离模具而设计的角度成型制品不容易脱离模具的现象残留在制品内部因各种原因产生的应力很多小分子连接而成的具有较大质量的长分子连熔体在模具内冷却状态之一的数学表示方法成型后制品拿出的过程毛坯加工或留有大量余量的待加工品配合CPU工作的马达完成一个组件或产品经过的步骤以塑料为原料生产的制品通过注射方式成型的模具倾斜于分型面、随模具的开闭产生相对运动的圆柱零件斜向镶块或滑动的镶块组合方式之一使镶件或拼块定位并紧固在一起的框套形结构零件成型模具内表面突起的组件使动模能固定在压机或注塑机上的L型垫块在腔内起部分成型作用,并在开模时把塑件从型腔内推出的零件用于推出塑件或浇注系统凝料的杆件支撑推出和复位零件,直接传递机床推出力的板件借助模具的闭合动作,强制推出机构复位的杆件浇口的相关尺寸熔融塑料经主流道直接进入型腔的进料方式沿塑料件内圆周扩展进料的浇口设置在模具的分型处 从塑件的内或外侧进料的方式从分流道道型腔方向的宽度逐渐增加的呈扇型的浇口浇口以镶块的形式存在推杆的一种,头部形状是圆柱型形工作截面为矩形的顶杆连接推件板与推杆固定板,传递推力的杆件与导柱相配合,用于初步确定模具起导向作用的部件,一般为圆柱体连接分流道合型腔的进料通道浇口的长度树脂流入模腔的点相对整体模腔的位置成型中埋入或随后压入塑件中的金属或其他材料的部件带有楔角,用于合模时楔紧滑块的零件成型塑件外表面的凹壮零件(包括零件的内腔和实体两部分)母模中的镶件拼块使定模固定在注塑机的固定工作台面上的板件 是模具的基座顶出制品机构的类型,布置方式的设计 包括模具和成型机两部分制品脱离模具可安全取出的时间与导柱滑配合,用于推出机构导向的圆柱形零件与推板导柱滑配合,用于推出机构导向的圆柱形零件在浇口流道末端用于储藏低温熔体的槽指凸模面或是动模面注射成型使用的模具的实际温度或设置温度支撑模具芯体和其它运动结构的板状模块为改变蒸汽或冷却水的流向而在模具内部设置的金属条或板将制品的一 部分设计成掏空的部分凸模中的镶拼件,一般成型出制品内表面的某个部分对应制品使用环境要求而设计的强度用于固定型心的板状零件为了方便出型或脱模设计的斜度指凹模面也叫定模指凸模面也叫公模具有斜导槽,用以使滑块随槽动作抽芯合复位动作的板状零件用于固定推杆位置,使其不发生位置变化的压板衡量材料产生弹性变形难易程度的指标模具在行腔压力下发生的弹性变形用于加热使用的环行加热部件在开模时限定某一板动作距离的板件为开设分流道设置的加热元件,保持融料的温度立式成型机中,模具天地开模(上下),分型面为水平状态也称无流道,浇口料在模具内部保持熔融状态的模具热塑性材料使用的注射成型模具调整高度使用的薄金属片按设计和工艺要求,用以拼合模具型腔或型芯的零件限制活动范围的零件限制位置的丁状零件以浇口形式存在的镶块形状像钩子,起拉料作用拉料部位呈圆型的零件但不是规范的圆形通用并具有互换性的模架可以滑动,带动侧型心完成出型,抽芯和复位动作的零件直接推出塑件的板壮零件起局部或整体推出塑件作用的环行或盘型零件位置不明显,一般可自动剪切的浇口为增强动模的钢度设在动模支撑板和动模座板之间的支撑零件在工艺上便于加工或修理与主体部件分开制造的局部零件石油提炼出的油脂,一般在模具行业中清洗附着的分解物或异物固定在要求位置操作或加工的区域,可能是安全区域也可能是非接触区域.工作的场合,一般指一线工作人员的工作区域而非文件处理办公室影响机械设备正常工作的现象含碳量在0.10%至0.30%之间,也称为软钢一般指在接近标准的基础上进行小尺寸的修改以达到更高的要求为了美观或防止潮湿,灰尘,碰伤等采取的保护措施多指可视或裸露在外面的并起到遮盖作用的部件可联网专用于绘制图纸的机械组装并研磨模具的工人齿轮状起到连接固定作用的部件用于储存部件相关信息的条状代码使用或控制机械设备人员外来语,日本,韩国称为课长,中国一般称科长对制品外观质量目视或测量的过程对制品内部质量目视或测量的过程组件前部或正对着使用者方向的部件组件后部或背向使用者方向的部件控制电源开启或关闭的按键小型工作车间或有几个人协作完成的一道工序的线体品质控制和管理的部门,国际上多与生产分开管理代替操作人员手动工作的半自动或自动机械设备用车刀对对旋转的工件进行车削加工的机床可以导致人体中毒的甲醇模具因潮湿和空气中的氧气发生的一种化学反应成红赫色物质换模就是切换其它模具,将原来的模具卸下换上另一副开机生产前将模具使用手动或机械自动夹持在成型机上一种对模具非正常状态进行处理并修理到正常状态的过程为了防止金属锐利的角划伤或使外形美观将锐角去处的一种方法提高钢强度和硬度的一种工艺方法淬火后一般都经过回火,可提高组织稳定性生产中常用的预备热处理工艺中空的小管,和套筒芯组成组件形成孔,顶出时只有套筒动作即热流道,熔体不形成冷却废弃的材料,在模具内保持熔体状态对生产的第一个制品进行外观检查或组装等实验,确保可继续生产在不防止阻碍制品正常应用的条件下被允许生产的托词铜制品,在电加工上对坯放电造型质量在允许范围内波动控制气体的阀与推板动作方向不一直的顶杆防止模具在运输过程中打开的锁紧件固定相关组件的条状零件无中间板的模具,看模后只见两个板有中间板的模具,可见三个板可加热的端口区域实现快速连接的接头扭转变形时,内力偶距称为扭距可代表综合质量的个别产品通常采用人,机,料,法,环来剖析问题的过程符合质量规定的产品不符合质量规定的产品在模具缝隙中形成的不良现象,片状的称为飞边树脂熔体形成泉流后在制品表面形成的不良现象由于收缩和其它原因引起的形状变化高聚物材料在长期应用情况下所表现出来的特性可锤炼可压延的程度,材料特性之一由于非均匀收缩或分子排列等引起的抽曲熔体相遇后在连接位置形成的不良现象制品脱落时发生的困难一种载荷类型注塑成型缺陷的一种包括料留痕,气留痕和型腔结构留痕注射成型缺陷的一种,表面有颗粒状物质高聚物材料在长期应用情况下所表现出来的特性由于内应力的存在发生的制品段列,裂纹现象熔体遇冷后产生的收缩现象大分子链停止运动,熔体开始凝固浇口中的熔体由流动到冷却静止的过程像泉水涌出,中间层熔体向两侧翻出的现象在常温常压以及不受载荷时发生的自由收缩现象注塑成型工艺中的有一个重要参数熔体分流后再次融合的一起的现象不同测控点的温度平均值熔体在流动时候速度的平均值由于不同区域压力差引起的熔体倒流现象树脂在计量时候形成推动螺杆向后移动的压力树脂计量时的外部部件,与螺杆配合进行计量融体在充填或保压时刻发生熔体溢出的现象聚合物该性方法的一种呈突起状区域,具体作用与设计相关流道系统的一部分,与主流道相连的小流道分支计算机模拟流动,保压,变形,气辅等模拟手段融体在充填时流动的基本模式类是于“ 7 ” 型的钩子妆连接方式测量流体黏度的测量仪器熔体填充到模具内部时,模具内的压力以曲线的形式描绘出腔内随时间,速度变化的压力曲线制品中心层处的温度单位长度的材料温度每升一度的伸长量制品各个部分尺寸的线形伸长或缩短的分布情况塑料在不同的温度下体积发生变化的现象单位时间内带走热量多少的度量塑料冷却的全过程熔体冷却的速度塑件冷却的速度成型周期的一部分,制品冷却直至可安全取出用于冷却塑件的系列冷却装置以及布置方式塑件从保压开始一直到顶出的一段时间用于冷却塑件分布在模具外部的水路一种流体的黏度测试仪器CAE辅助分析的一种,用于模拟冷却过程设计在模具内部的冷却液通道,用以控制所要求的模温制品的两个和模具接触表面的温度差分布情况保压后螺杆所剩余的计量长度塑料制品壁部的厚度变化断开的端面起到组装或固定作用的孔(不一定是圆形)实际载荷或受力直线的过度联系常使用的弧,可以起到加强或美观的作用物品,制造生产的部件应用在不同环境下的轴,可起到对称基准或连接等作用研磨,组装,修理模具等工作没有进行细致加工的原材料由铜和锌组成的合金尖锐的比较小的突出部分用于浇注铸件的钢用于固定模具的夹具造型艺术术语,指界定表现对象形体范围的边缘线给予说明加工尺寸或外观图纸制作过程一种采用高压放电对金属部件加工的工艺铜材料,用于放电加工的阴模,放电加工完毕后被加工部件形成阳模筒装管子组装研磨工人研磨抛光材料局部抵抗硬物压入其表面的能力在应力的情况下出现在应力聚集的现象在应力的情况下发生断裂在恒温和应变情况下应力随时间延长而减小的情况产生 应力集中的区域应力发生变化的特点由喷嘴到型腔之间的进料通道组成包括主,分,浇口合冷料穴为了提高或降低某中特性在塑料材料中添加了其它成分高分子材料的一种添加到高分子内部改善塑料有关性能的成分填充过程熔体流动的各种形式熔体填充到模具的整个过程单位时间内添入模腔的熔体量熔体填充到模具阶段熔料充满型腔所用的时间严格上讲包括保压填充时间熔体从料膛注入模具内所需要的力一定量的熔体材料占据空间的部分一种可发生弯曲的载荷类型熔体填充到模具内流动均匀性的一种表现形式螺杆速度及压力控制模具腔内熔体的体积流量形式熔体流过的长度壁厚与熔体流动距离的比塑料在流动或冷却的过程呢中,发生在分子链定向的一种行为CAE辅助分析虚拟流动的一种方式截面为圆形的流道三角形状起到加强或者支撑作用的筋等截面的形状为半圆形的流道将热量从热的地方向冷的地方传导速度的量度控制热量传导的仪器设备单位时间内热能传递的量度冷却水管在墨菊内部布置和排列的方式粘流态树脂冷却成玻璃态时刻的温度Pack结束后,螺杆基本静止不动而维持压力不便的阶段填补收缩时保持设置压力的时间盛放待加工树脂塑料的容器。
第42卷第8期2023年8月硅㊀酸㊀盐㊀通㊀报BULLETIN OF THE CHINESE CERAMIC SOCIETY Vol.42㊀No.8August,2023水化热抑制剂对复合胶凝材料体系早期水化动力学的影响曾柯林1,温东昌1,杨㊀蓉2,孙㊀涛2,王雷冲2,韩金龙3(1.中交路桥建设有限公司,北京㊀101100;2.中山市武汉理工大学先进工程技术研究院,中山㊀528400;3.珠海春禾新材料研究院有限公司,珠海㊀519000)摘要:本文研究了水化热抑制剂(TRI)对水泥-粉煤灰-矿渣复合胶凝材料早期水化过程㊂通过改变矿物掺合料在胶凝材料中的质量占比以及TRI 的掺量,研究了胶凝材料的水化特性,并基于Krstulovic-Dabic 水化动力学模型计算了反应速率常数㊁几何晶体生长指数等动力学参数㊂结果表明,矿物掺合料和TRI 复合使用会延缓胶凝材料水化并降低最大放热速率;复合胶凝材料的水化过程均有结晶成核与晶体生长㊁相边界反应以及扩散3个阶段,Krstulovic-Dabic 水化动力学模型能较好地模拟各复合胶凝材料的水化过程;矿物掺合料和TRI 会影响复合胶凝材料水化产物的结晶成核以及晶体生长,并降低复合胶凝材料各阶段的水化速率㊂关键词:水化热抑制剂;粉煤灰;矿渣;水化历程;水化动力学;Krstulovic-Dabic 模型中图分类号:TU528.42㊀㊀文献标志码:A ㊀㊀文章编号:1001-1625(2023)08-2712-10Effect of Temperature Rising Inhibitor on Early Hydration Kinetics of Composite Cementitious MaterialZENG Kelin 1,WEN Dongchang 1,YANG Rong 2,SUN Tao 2,WANG Leichong 2,HAN Jinlong 3(1.Road &Bridge International Co.,Ltd.,Beijing 101100,China;2.Wuhan University of Technology Advanced Engineering Technology Research Institute of Zhongshan City,Zhongshan 528400,China;3.Zhuhai Chunhe New Material Research Institute Co.,Ltd.,Zhuhai 519000,China)Abstract :The effect of temperature rising inhibitor (TRI)on early hydration process of cement-fly ash-slag composite cementitious material was studied.By changing mass proportion of mineral additives in gel materials and amount of TRI,the hydration characteristics of cementitious materials were measured.The reaction rate constant,geometric crystal growth index and other dynamic parameters were calculated based on the Krstulovic-Dabic model.The results show that mineral additives and TRI delay the time of hydration and reduce the maximum hydration rate of cementitious materials.The hydration process of composite cementitious material can involve three stages,i.e.nucleation and crystal growth,interactions at phase boundaries and diffusion.The hydration process can be predicted by Krstulovic-Dabic model well.Mineral additives and TRI affect the crystallization of nucleation and crystal growth,and reduce the hydration rate of composite cementitious material at every stage.Key words :temperature rising inhibitor;fly ash;slag;hydration process;hydration kinetics;Krstulovic-Dabic model 收稿日期:2023-03-03;修订日期:2023-06-06基金项目:2019年度中山市高端科研机构创新专项(2019AG010)作者简介:曾柯林(1985 ),男,高级工程师㊂主要从事公路桥梁工程的研究㊂E-mail:413907478@ 0㊀引㊀言我国跨海大桥中使用的大体积海工混凝土,其胶凝体系一般由水泥㊁粉煤灰和/或矿粉材料组成[1-3]㊂粉煤灰和矿粉玻璃体早期水化时,由于受到溶解-沉淀机制的影响,水化速率较小,因此通过单掺或复掺辅助胶凝材料替代部分水泥能缓解水泥矿相快速水化释放热量而造成混凝土内外温差的现象[4-5],从而抑制温度收缩造成的有害裂缝[6-9]㊂此外,还通过引入水化热抑制剂对水泥水化速率进行调控,在不影响强度发展第8期曾柯林等:水化热抑制剂对复合胶凝材料体系早期水化动力学的影响2713㊀的同时有效降低了水化温度并获得了足够的凝结时间㊂水化热抑制剂主要分为羟基类化合物和反应吸热型盐类抑制剂:前者是通过生成氢键并与水分子缔合后在水泥表面形成水膜,从而延缓水泥水化;后者主要是通过盐类溶解吸热,从而中和水化放热,降低总热㊂辜振睿等[8]研究了多羟基羧酸酯类水化热抑制剂对纯水泥体系的影响,结果表明该类水化热抑制剂能有效降低水泥早期的水化放热速率和峰值,降低早期强度,但是对后期强度没有影响;严宇[10]㊁秦媛[11]和陈炜一等[12]研究了淀粉基水化热抑制剂对掺25%(质量分数)粉煤灰胶凝材料的影响,发现该类水化热抑制剂对早期水化放热的抑制作用明显,会大幅度降低早期强度,但对后期强度影响较小㊂魏小胜等[13]研究了糊精类水化热抑制剂对水泥-粉煤灰体系的影响,结果表明该类水化热抑制剂能显著降低水化放热速率峰值,抑制水化反应,但抑制作用主要发生在水化前7d㊂以上研究表明矿物掺合料可以缓解水泥水化快速释放热量的情况,水化热抑制剂可以缓解水泥水化同时降低水化放热速率,二者均可减少混凝土内外温差,抑制温度收缩造成的有害裂缝㊂而目前对于水化热抑制剂是否会和双掺粉煤灰和矿粉胶凝材料体系产生复合变化特征的研究较少㊂因此,本文采用大体积混凝土中常用的矿粉-粉煤灰双矿物掺合料体系,研究水化热抑制剂对水泥-粉煤灰-矿渣复合胶凝材料体系早期水化的影响㊂应用动力学可用来研究各种化学㊁物理因素对化学反应速率的影响,通过控制反应条件和速率实现对胶凝材料凝结硬化的调控㊂国内外研究人员[14-15]从理论角度分析和总结了水泥基胶凝材料的水化过程,其中被广泛接受的是Krstulovic-Dabic水化模型㊂本文通过调整矿物掺合料在胶凝材料中的质量占比以及水化热抑制剂(temperature rising inhibitor,TRI)的质量掺量,探究了其对胶凝材料水化特性的影响,并应用Krstulovic-Dabic模型研究其对胶凝材料的水化机理和水化过程的影响,从而为TRI和矿物掺合料在海工大体积混凝土中的应用提供基础理论支撑㊂1㊀实㊀验1.1㊀原材料原材料包含P㊃II42.5水泥㊁I级粉煤灰以及S95级矿渣粉,分别由海螺水泥有限公司㊁珠海市粤珠环保技术有限公司以及粤裕丰钢铁有限公司生产,原材料的主要化学组成和基本物理性能如表1和表2所示㊂通过扫描电子显微镜(SEM)对三种原材料微观形貌进行表征,SEM照片如图1所示,水泥与矿渣呈不规则块状,粉煤灰呈光滑圆球状㊂三种原材料的颗粒粒径分布和通过率如图2所示㊂由图2可知,在这三种原材料中,粉煤灰颗粒相对较细,其中值粒径D50为2.42μm,矿渣和水泥的D50分别为4.58和8.67μm㊂采用的水化热抑制剂为中山市灵湾新材料有限公司生产的淀粉基类水化热抑制剂,其红外光谱如图3所示, 3440cm-1处的宽峰主要是由羟基( OH)的伸缩振动引起的,2870cm-1处的吸收峰是由淀粉的环状骨架振动引起的,1020和1100cm-1处的吸收峰是由C O基团振动引起的,879cm-1处的吸收峰是由C O C 基团伸缩振动引起的㊂根据FTIR谱显示,水化热抑制剂中存在大量的亲水性基团 OH㊂表1㊀原材料的主要化学组成Table1㊀Main chemical composition of raw materialsRaw materialMass fraction/%Al2O3SiO2Fe2O3CaO K2O TiO2SO3P2O5Na2O MgO F LOICement 6.4521.75 3.2458.020.740.51 2.470.250.14 2.25 3.80 Slag15.4530.60 1.0736.660.510.95 2.610.090.558.900.82 1.06 Fly ash32.5652.2 4.01 3.880.890.55 1.010.120.790.840.21 2.16表2㊀原材料的基本物理性能Table2㊀Basic physical properties of raw materialsProperty Cement Slag Fly ash Initial setting time/min157 Final setting time/min189 Standard consistency/%27Mass quality K 1.932714㊀水泥混凝土硅酸盐通报㊀㊀㊀㊀㊀㊀第42卷续表Property Cement Slag Fly ash Basicity coefficient M 00.99 Activity index at 3d /% 86.374.9Activity index at 7d /% 85.279.0Activity index at 28d /% 97.195.1图1㊀水泥㊁粉煤灰和矿渣的SEM 照片Fig.1㊀SEM images of cement,fly ash andslag 图2㊀水泥㊁粉煤灰和矿渣的颗粒粒径分布和通过率Fig.2㊀Particle size distribution and passing percent of cement,fly ash andslag 图3㊀水化热抑制剂的FTIR 谱Fig.3㊀FTIR spectrum of TRI1.2㊀测试方法净浆配合比如表3所示㊂采用TAM 等温量热仪连续测定净浆在20ħ环境温度下水化72h 后的放热速率和累积放热量㊂为了保持浆体温度和环境温度相同,在搅拌前将胶凝材料和水放置在同温度下的恒温箱中,净浆搅拌均匀后立即放入等温量热仪设备中㊂根据测试的水化热数据,采用Knudson [16]提出的水化动力学公式(1)求出最大放热量Q max ㊂1/Q (t )=1/Q max +t 50/Q max (t -t 0)(1)式中:t 0为加速期开始时间,t 50为半衰期,Q (t )为胶凝材料从加速期开始水化t 时所放出的热量,Q max 为胶凝材料在ɕ龄期时的水化放热量(即最大放热量)㊂采用耐驰热重分析仪对样品进行热分析㊂TG 测试条件:30~1000ħ,氮气气氛,升温速度为10ħ/min㊂DTG 为TG 曲线对温度的一阶导数㊂为了终止样品水化,对样品进行如下处理:先用异丙醇浸第8期曾柯林等:水化热抑制剂对复合胶凝材料体系早期水化动力学的影响2715㊀泡样品1d,然后更换新异丙醇溶液再次浸泡半天,最后将样品置于真空干燥器中连续抽真空[17-18]㊂为修正其他水化产物和碳化对结果的影响,采用切线法计算Ca(OH)2(CH)的含量[19-20]㊂采用Bruker D8X 射线衍射仪(XRD)定性测试各样品在1㊁3和28d 龄期时的物相组成,样品终止水化方式与上述测试相同㊂采用Phenom 扫描电子显微镜观察各样品在1㊁3和28d 龄期时的微观形貌,样品终止水化方式与上述测试相同㊂表3㊀净浆配合比Table 3㊀Mix proportion of pasteSampleWater-binder ratio Mass fraction /%Cement Fly ash Slag TRI C 0.33100 CFASG 0.33402535 CFASG-T0.5%0.334025350.5CFASG-T1.0%0.33402535 1.0CFASG-T1.5%0.33402535 1.5㊀㊀Note:C means that cementitious material is cement;CFASG means that cementitious material is 40%cement,35%slag and 25%(all are mass fraction)fly ash;T x %means that the mass fraction of TRI is x %of cementitious material.2㊀结果与讨论2.1㊀水化放热特性图4为水化温度为20ħ时复合胶凝材料的水化放热特性,表4为水化温度为20ħ时复合胶凝材料的水化放热特征值㊂由图4(a)和表4可知,矿物掺合料取代部分水泥后,诱导期略延长,达到最大放热速率的时间增加,同时最大水化放热速率明显降低,由13.30J㊃g -1㊃h -1降低到6.66J㊃g -1㊃h -1,降低了49.9%㊂当进一步掺入不同比例TRI 后,所有胶凝材料的诱导期以及达到最大放热速率的时间明显延长㊂与未掺TRI 组相比,当TRI 的掺量(质量分数)为1.5%时,经过65.56h 才达到最大水化速率,延缓了近41.56h㊂由此可知,矿物掺合料主要是降低胶凝材料的早期水化放热速率,而TRI 则能延缓早期水化㊂由图4(b)和表4可知,随着矿物掺合料和TRI 的掺入,早期的总水化热量均减小㊂与C 相比,CFASG 水化3d 的累积放热量由283.6J /g 降到187.4J /g,降低了33.9%;最终的放热量Q max 由328.9J /g 降到237.5J /g,降低了27.8%㊂与CFASG 相比,CFASG-T1.5%水化3d 的累积放热量由187.4J /g 降到120.6J /g,降低了35.6%;而最终的放热量Q max 几乎没有变化㊂这说明矿物掺合料和TRI 均能降低胶凝材料的总水化放热量,其中矿物掺合料是降低胶凝材料水化放热量的主要因素,而TRI 主要是延缓胶凝材料早期水化,对最终的放热量基本没影响㊂图4㊀水化温度为20ħ时复合胶凝材料的水化放热特性Fig.4㊀Characteristics of hydration heat evolution of composite cementitious materials with hydration temperature at 20ħ2716㊀水泥混凝土硅酸盐通报㊀㊀㊀㊀㊀㊀第42卷表4㊀水化温度为20ħ时复合胶凝材料的水化放热特征值Table 4㊀Characteristic values of hydration heat evolution of composite cementitious materialswith hydration temperature at 20ħSampleTime of second heat evolution peak t 2/h Rate of second heat evolution peak q max /(J㊃g -1㊃h -1)Total heat evolution Q /(J㊃g -1)24h 48h 72h Q max C 10.8113.30212.9268.5283.6328.9CFASG 14.00 6.66123.0162.4187.4237.5CFASG-T0.5%18.16 4.4690.1146.6171.8240.4CFASG-T1.0%31.83 4.6353.8128.4156.1235.3CFASG-T1.5%65.56 4.9438.440.9120.6233.12.2㊀相组成和微观结构图5为不同复合胶凝材料水化1㊁3和28d 的XRD 谱㊂由图5(a)可知,水化1d 时,CFASG 已生成了Ca(OH)2和钙矾石等产物㊂随着TRI 掺量的增加,水化产物的衍射峰强度逐渐降低,对于TRI 掺量为1.5%的CFASG-T1.5%而言,水化产物衍射峰几乎消失,这表明TRI 能显著降低胶凝材料在1d 时的水化程度㊂由图5(b)可知,水化3d 时,各胶凝材料的水化产物衍射峰强度均较高,其中CFASG-T0.5%的水化产物衍射峰强度与CFASG 相差不多㊂随着水化的进行,当水化龄期为28d 时,对于各TRI 掺量的胶凝材料,硬化浆体中水化产物的衍射峰强度几乎相同,这表明水化热抑制剂对胶凝材料的水化抑制作用主要发生在早期,随着龄期的增长,掺TRI 的胶凝材料水化程度将逐渐恢复至与未掺TRI 胶凝材料时相近㊂值得注意的是,水化1d 时CFASG 水化产物衍射峰强度明显低于C 的衍射峰强度,随着水化的进行,CFASG 水化产物衍射峰强度与C 的衍射峰强度差距逐渐减小,但始终低于C㊂图5㊀复合胶凝材料硬化浆体的XRD 谱Fig.5㊀XRD patterns of hardening slurry of composite cementitious materials 由于胶凝材料的水化产物受热会分解,并且每种水化产物的分解温度不同,因此可以通过热重分析来研究水化产物㊂室温到300ħ为水化硅酸钙(C-S-H)㊁水化铝酸钙㊁单硫型水化硫铝酸钙(AFm)㊁高硫型水化硫铝酸钙(AFt)等水化产物失水分解,370~450ħ为CH 的分解[19]㊂图6为复合胶凝材料的水化产物在1㊁3和28d 的TG 和DTG 曲线(HC 为水化碳铝酸钙,MC 为碳酸酯),表5为切线法计算的复合凝胶材料中Ca(OH)2含量㊂当水化1和3d 时,300ħ前C 硬化浆体的失重速率显著大于CFASG,而CFASG 硬化浆体的失重速率明显大于掺TRI 样品,表明C 中水化产物含量大于CFASG,而CFASG 的水化产物含量大于掺TRI 的复合胶凝材料;在370~450ħ,C 硬化浆体的失重速率显著大于CFASG,CFASG 硬化浆体的失重速率仍然大于掺TRI 样品,表明C 中CH 含量大于CFASG,CFASG 中CH 含量大于掺TRI 的复合胶凝材料,这与通过切线法计算得到的CH 含量趋势一致㊂当水化龄期为28d 时,掺TRI 和未掺TRI 的复合胶凝材料的TG 和DTG 曲线几乎重叠,并且反应生成的CH 含量也几乎相等,再次证明TRI 不会影响复合胶凝材料的最终水化程度㊂图7为C㊁CFASG 和CFASG-T1.5%不同龄期硬化浆体的SEM 照片㊂水化1d 时,C 中的颗粒表面已覆第8期曾柯林等:水化热抑制剂对复合胶凝材料体系早期水化动力学的影响2717㊀盖了绒毛状的C-S-H 凝胶(见图7(a));CFASG 中只有水泥颗粒表面生成绒毛状的C-S-H 凝胶(见图7(d)),但由于水泥只占总粉料的40%,生成的C-S-H 凝胶含量明显少于C 中生成的C-S-H 凝胶含量;而CFASG-T1.5%中的颗粒则几乎未发生水化反应(见图7(e))㊂当水化3d 时,样品中的水泥和矿粉颗粒均发生了水化,且矿粉水化程度不及水泥,而粉煤灰未明显水化㊂当龄期达到28d 时,样品均呈现出致密的形貌㊂结果表明,水化热抑制剂对于硬化浆体微观结构的负面作用主要发生在早龄期;随着水化的进行,水化热抑制剂对浆体微观结构的负面影响已不明显㊂图6㊀复合胶凝材料硬化浆体的TG 和DTG 曲线Fig.6㊀TG and DTG curves of hardening slurry of composite cementitious materials表5㊀切线法计算的复合凝胶材料中Ca (OH )2含量Table 5㊀Ca (OH )2content of composite cementitious materials calculated by tangent methodTime /d Mass fraction /%C CFASG CFASG-T0.5%CFASG-T1.0%CFASG-T1.5%111.52 4.94 3.37 2.28 1.85314.497.24 6.95 5.87 4.872817.617.907.747.907.822718㊀水泥混凝土硅酸盐通报㊀㊀㊀㊀㊀㊀第42卷图7㊀复合凝胶材料硬化浆体的SEM照片Fig.7㊀SEM images of hardening slurry of composite cementitious materials2.3㊀水化放热动力学分析Krstulovic-Dabic模型认为水泥基胶凝材料的水化由结晶成核与晶体生长(NG)㊁相边界反应(I)和扩散(D)三个反应组成[15]㊂结晶成核与NG阶段微分式如(2)所示㊂dα/d t=F1(α)=Kᶄ1n(1-α)[-ln(1-α)](n-1)/n(2) I阶段微分式如(3)所示㊂dα/d t=F2(α)=Kᶄ2㊃3(1-α)2/3(3) D阶段微分式如(4)所示㊂dα/d t=F3(α)=Kᶄ3㊃3(1-α)2/3/[2-2(1-α)1/3](4)式中:α为水化程度,n为反应级数,t为水化时间,Kᶄi为表观反应速率常数,F i(α)为反应机理函数㊂本文将复合胶凝材料视为均质体进行处理,并以整个复合胶凝材料为研究对象进行动力学分析㊂图8为复合胶凝材料在20ħ时的水化反应速率曲线,结果表明所研究材料的水化动力学过程均经历NG-I-D 阶段㊂由图8(a)可知,模型模拟的各阶段曲线均能较好地拟合纯水泥实际水化热速率㊂图8(b)为复合胶凝材料的水化过程,该过程由快速的水泥水化和较慢的矿物掺合料水化组成,在水化最初的几小时内,复合胶凝材料中水泥快速水化生成了大量水化产物C-S-H,并伴随着孔溶液pH值的快速增长,当CH达到过饱和后形成稳定晶核[9],粉煤灰和矿粉由于早期水化反应速率较慢,因此主要发挥物理填充作用,增大复合胶凝材料的有效水胶比,并为水化产物提供初始成核点,故其水化的NG阶段模拟效果好㊂由于矿物掺合料占总胶凝材料的60%,矿粉水化发生在I阶段,粉煤灰的火山灰反应产生的热效应在D阶段,从而使得I和D阶段的模拟误差增大,但仍能较好地反映实际的水化㊂由图8(b)~(e)可知,复合胶凝材料掺入水化热抑制剂后,相边界反应控制的时间增加,这是由于水化热抑制剂对水泥和矿物掺合料具有延缓效果㊂表6为不同TRI掺量的复合凝胶材料的动力学参数㊂其中α1为反应控制机制由NG转变为I时的水化程度,α2为反应控制机制由I转变为D时的水化程度㊂由表6可知,矿物掺合料取代部分水泥后,n值略微增加,说明大掺量复掺粉煤灰和矿粉对水化产物的产生过程影响不大㊂而在复合胶凝材料中掺入水化热抑第8期曾柯林等:水化热抑制剂对复合胶凝材料体系早期水化动力学的影响2719㊀制剂,n 值显著增加,表明水化热抑制剂会大大影响复合胶凝材料水化产物的结晶成核以及晶体生长[21]㊂图8㊀20ħ时复合胶凝材料的水化反应速率曲线Fig.8㊀Hydration rate curves of composite cementitious materials at 20ħ表6㊀不同TRI 掺量的复合凝胶材料的动力学参数Table 6㊀Kinetic parameters of composite cementitious materials with different TRI contentSamplen K ᶄ1K ᶄ2K ᶄ3Kinetic α1α2C 1.95550.054960.014870.00297NG-I-D 0.2100.387CFASG 2.00640.045210.010190.00132NG-I-D 0.1170.182CFASG-T0.5% 2.67670.033230.006770.00101NG-I-D 0.0950.286CFASG-T1.0% 3.19880.031030.006680.00091NG-I-D 0.1060.180CFASG-T1.5% 4.63150.024550.006300.00085NG-I-D 0.1300.253各复合凝胶材料的反应速率K ᶄ1约是K ᶄ2的3~5倍,约是K ᶄ3的15~35倍㊂结果表明,在常温时NG 过程的反应速率明显比I 和D 过程的反应速率大㊂这是因为在NG 过程中,水泥发生自催化反应,迅速生成水化产物㊂与纯水泥胶凝材料相比,掺有矿粉和粉煤灰的复合胶凝材料的K ᶄ1㊁K ᶄ2和K ᶄ3值均减小㊂这是因为水泥被矿物掺合料取代后,CH 的总生成量降低且被矿物掺合料的火山灰反应消耗,延长了达到过饱和状态的时间,因此析晶沉淀速率受到影响㊂同时,水泥水化生成的钙离子含量减小,从而使扩散到矿物掺合料表面的钙离子含量减小[21]㊂另外,由于D 阶段浆体较致密,使得水化速率降低㊂与CFASG 相比,掺入水化热抑制剂后其他凝胶材料的K ᶄ1㊁K ᶄ2和K ᶄ3值均减小,这是因为水化热抑制剂在水泥水化早期能持续抑制C-S-H 凝胶的成核过程,进而影响C-S-H 凝胶成核生长,CH 的生成量随之降低,从而进一步抑制矿物掺合料的火山灰反应[11]㊂矿物掺合料取代水泥后,α1和α2减小,说明其在较低水化程度下发生了NG ңI 和I ңD 反应控制机制的转变㊂这是因为水泥被矿物掺合料取代后,CH 生成量随之降低,矿物掺合料受碱性离子激发发生反应,使得材料在较低水化程度下发生反应机制的转变㊂在复合胶凝材料中掺入水化热抑制剂后,α1先减小再增大,表明NG 阶段的水化程度先减小后增大㊂由α2可知,水化热抑制剂会抑制材料的D 阶段反应程度㊂2720㊀水泥混凝土硅酸盐通报㊀㊀㊀㊀㊀㊀第42卷3㊀结㊀论1)粉煤灰㊁矿渣和TRI三种材料复合使用时能有效缓解胶凝材料早期集中放热现象,其中粉煤灰和矿渣主要降低胶凝材料的最大放热速率,TRI延缓水化反应㊂2)粉煤灰㊁矿渣和TRI三种材料复合使用时也会影响水化放热量,矿粉和粉煤灰会降低胶凝材料的早期和最终的水化放热量,而TRI只会降低早期水化放热量,但对最终水化放热量没有任何影响㊂3)采用Krstulovic-Dabic水化动力学模型计算的曲线能较好地分段模拟不同掺量TRI的水泥-粉煤灰-矿粉复合胶凝材料体系的实际水化速率曲线;其水化动力学过程均可表示为NG㊁I和D3个阶段,且水化机理均为NGңIңD㊂4)矿渣㊁粉煤灰和TRI三种材料复合使用会影响胶凝材料水化产物的结晶成核以及晶体生长,即动力学参数n增大,其中TRI影响最明显;同时会降低复合胶凝材料各阶段的水化速率,即Kᶄ1㊁Kᶄ2和Kᶄ3减小㊂参考文献[1]㊀谭㊀昱,陈儒发,谭逸波,等.港珠澳大桥低温升抗裂C45承台大体积混凝土研究与应用[J].公路,2016,61(5):282-288.TAN Y,CHEN R F,TAN Y B,et al.Research and application of C45mass concrete with low temperature rise and crack resistance for bearing platform of Hong Kong-Zhuhai-Macao bridge[J].Highway,2016,61(5):282-288(in Chinese).[2]㊀王冬松.杭州湾跨海大桥高性能海工混凝土配合比设计[J].公路,2009,54(7):299-303.WANG D S.Mix proportion 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Hydration characteristics of tricalcium aluminate phase in mixescontaining h -hemihydate and phosphogypsumM.M.Radwan a ,M.Heikal b ,*aNational Research Center,Dokki,Cairo,EgyptbChemistry Department,Faculty of Science,Zagazig University,Benha Branch,Benha,EgyptReceived 19November 2002;accepted 14June 2004AbstractThe tricalcium aluminte phase was prepared from pure chemicals on a laboratory scale.Five mixes were formulated from the prepared C 3A phase,h -hemihydate,phosphogypsum,calcium hydroxide and quartz.Different mixes were hydrated at various time intervals,namely,6,24,72and 168h.The kinetics of hydration was measured from chemically combined water and combined lime contents.The phase compositions and microstructures of the hydrated products were studied by X-ray diffraction (XRD),differential thermal analysis (DTA)/TG,scanning electron microscopy (SEM)techniques and FT-IR spectroscopy.This work aimed to study the effect of partial to full substitution of phosphogypsum by h -hemihydate on the hydration characteristics and microstructures of tricalcium aluminte phase.The results showed that the combined lime slightly increases with the increase of amounts of phosphogypsum.The XRD patterns showed the increase in the intensities of monosulphate and different forms of calcium aluminate (C 4AH 13and C 4AH 19)with phosphogypsum content.Ettringite is less stable than monosulphoaluminate,so it transformed into monosulpho-aluminate after 24h,which persisted up to 168h.The mechanism of the hydration process of C 3A phase in the presence of phosphogypsum proceeds in a similar path as with h -hemihydate.Phosphogypsum reacts with C 3A in the presence of Ca(OH)2forming sulphoaluminate hydrates,which are responsible for setting regulation in cementitious system.D 2004Elsevier Ltd.All rights reserved.Keywords:Phosphogypsum;Tricalcium aluminate;Hydration kinetics;X-ray diffraction and microstructure1.IntroductionLarge quantities of industrial by-products are produced every year by chemical and agricultural industrials.These materials have dual problems of disposal and health hazards.In Abo-Zaabal,Cairo,Egypt,a few factories produces phosphatic fertilizer and chemical industries,which generate large quantities of phosphogypsum that are currently being disposed by damping into pond or wastelands.In Egypt,phosphogypsum is produced from phosphoric acid manu-facture by dihydrate process.The annual production of phosphogypsum is about 300,000tons,which causes serious storage and environmental pollution.Due toincreasing concerns about environmental pollution,it is important to utilize these wastes as building materials to save the environmental from degradation.The use of phosphogypsum is of interest for many researchers [1–6].Attempts have been made by several authors [7–9]to use phosphogypsum and fluorogypsum in the manufacture of cement.The impurities of P 2O 5,F À,organic matter and alkalis present in the gypsum adversely affect the setting and hardening of cement [10].The effect of waste phosphogyp-sum and fluorogypsum on the properties of Portland cement and Portland slag cement was studied.The natural gypsum was blended with by-product gypsum to reduce the adverse effect of impurities of P 2O 5and F Àpresent in this type of gypsum.This work aimed to study the possibility of using phosphogypsum as a set controller to the hydration process of C 3A in the presence and in the absence of h -hemihydate.0008-8846/$-see front matter D 2004Elsevier Ltd.All rights reserved.doi:10.1016/j.cemconres.2004.06.037*Corresponding author.Tel./Fax:+2013222578.E-mail address:ayaheikal@ (M.Heikal).Cement and Concrete Research 35(2005)1601–1608Although the proportion of C3A in OPC is relativity low,it exerts a very significant role on the setting property and heat of hydration during hydration.In a previous study,it has been shown that the presence of phosphogypsum in cement pastes did not adversely affect the setting times and improves the workability of cement pastes.Phosphogypsum enhances the kinetics of hydration and mechanical proper-ties as well as the rate of hydration as indicated from differential thermal analysis(DTA)up to90days[11].In the system CaO d Al2O3d H2O,different hydration products of calcium aluminate hydrates have been identified. CAH10,C2AH8and C4AH19were formed at temperatures below508C.It was found that the metastable hydration products of C3A were C2AH X and C4AH X.In saturated lime solution,the formation of C4AH13or C3AH6formation depends on the condition of hydration reactions[12,13].It was stated that the role of gypsum in the retardation of the reaction of C3A is mainly due to the reduction of the solubility of C3A as a result of the sulphate reaction.The formation of thin layer of ettringite on the surface of anhydrous C3A crystal will control the diffusion of SO42Àions through this layer.The formation of ettringite directly on the C3A grains produces a sort of crystallization pressure, which leads to bursting of the ettringite layer caused by the pressure of crystallization.This burst section is sealed by newly formed ettringite.When the sulphate content is depleted(insufficient sulphate ions to allow formation of ettringite),on further hydration of the C3A,ettringite converts to monosulphate[14,15].A comparison study of the hydration characteristics of C3A in the presence of raw gypsum and phosphogypsum was done.2.Materials and experimental2.1.Preparation of tricalcium aluminate(C3A)C3A had been prepared at the laboratory by firing at appropriate temperatures the stoichiometric composition of this phase using highly pure limestone(99.0%CaCO3)and technically pure A12O3(99.0%)with molar ratio3:1,CaO/Al2O3,respectively;then,the mixture was pressed under 100kg/cm2pressure.The prepared specimens were calcined at10008C for2h.After cooling,they were crushed and ground in absolute ethanol to complete homogeneity,then remoulded and fired at13508C for3h.Firing of the mix was repeated until nearly complete formation of this phase occurred.The final product was tested for their free lime and insoluble residue contents.The fired products were crushed and finely ground to a Blaine surface area of3000cm2/g. The XRD traces of the prepared C3A are shown in Fig.1. The chemical composition of the utilized phosphogypsum was shown in Table1.DTA thermograms of h-hemihydrate and phosphogypsum are represented in Fig.2.The thermo-gram of h-hemihydrate shows endothermic peak located at 2008C.On the other hand,phosphogypsum shows two endothermic peaks,the first located at1708C,which is due to dehydroxlation of1.5molecules of water of phospho-gypsum to form h-hemihydrate and the second peak at200 8C is due to the decomposition of h-hemihydrate to CaSO4.2.2.Preparation of the anhydrous mixes and hydrating pastesTable2shows the prepared mixes of C3A phase with other ingredients.For each mix,these were thoroughly mixed in a porcelain ball mill to ensure complete homogeneity.h-hemihydrate was prepared form the nearly pure alabaster gypsum sample(99%CaSO4).It was preground to a Blaine surface area of c3000cm2/g.The required amount of mixing water was added to each mix and the ingredients were mixed for3min and the pastes then moulded into1-in.cubes which were compacted to remove air bubbles and then in a100%RH at23F28C for24h. After demoulding,the cubes were stored under water until time of testing.In this study,h-hemihydrate was used instead of gypsum because of the relatively higher solubility of h-hemihydrate than that of raw gypsum to detect the different hydration reaction rates of phosphogypsum and h-hemihydrate.The main target of this work is the investigation of the acceleration effect of the impurities that is present in phosphogypsum,which was emphasized in thisinvestiga-Fig.1.XRD patterns of the prepared anhydrous C3A phase.M.M.Radwan,M.Heikal/Cement and Concrete Research35(2005)1601–16081602tion as being found in the results of combined water.Ca(OH)2was added to maintain the condition as in the case of OPC clinker as it is incorporated in the reaction of the aluminate phase with the calcium sulphate (especially with the free excess C 3A phase)[13].Finely ground quartz silica was added to mixes at a constant proportions (10mass%).The presence of finely ground quartz affects the crystal-lization of ettringite and helps to maintain the system in similar conditions to which cement is used [16].2.3.Methods of investigationIn this investigation,the compressive strength was not considered as the hydration products are expansive and have no mechanical properties but we mean only the crushing and grinding of the sample for the rest of tests.Pulverizing 10g of representative sample after each hydration period stopped the hydration reaction;this was placed in a beaker containing 1:1methanol–acetone mixture,and then mechan-ically stirred for 1h.The mixture was filtered through a gooch crucible,G4,and washed with ether.The solid was then dried in a CO 2-free atmosphere at 708C for 30min to evaporate the alcohol.The combined water is the percent of ignition loss of dried samples on the ignited weight basis.Approximately 2g of the predried sample was gradually ignited up to 10008C for 30min soaking time.The results of combined waterwere corrected for the water contents of free lime and the raw materials (phosphogypsum and h -hemihydate).The determination of Ca(OH)2is based on extraction of Ca 2+by ethylene glycol method [17].Free lime present in the sample will react with ethylene glycol,forming calcium glycolate.This glycolate was titrated with standard hydro-chloric acid.About 0.5g of sample is placed in small conical flask with 25ml of ethylene glycol.The flask is closed with air reflux and shaken in a water bath at 60–708C for 1h.The sample was filtered through filter paper on a porcelain crucible;the filter paper was washed three times with about 15ml ethylene glycol.The filtrate was titrated with standardized 0.1N aqueous HCl by using phenolph-thalein as indicator until the pink colour just disappeared (end point).The combined lime was calculated from the difference between lime added at zero time (15mass%),and the residual free lime at the prescribed time.The crystalline phases present were identified using X-ray diffraction (XRD)technique.This technique was also carried out for some selected samples of the hydrated cement pastes.Ni-filtered Cu–k a radiation at 40kV and 25mA with a scanning speed 2h of 82min À1was used in a Philips diffractometer (PW 1050/70).The sample was finely ground to pass a 200-mesh sieve.The XRD patterns were converted to a series of lattice spacings d 2and the relative intensities were visually estimated.Some selected hydrated samples were investigated using a differential thermal analyzer of the type Schimaduz DTA-30thermal analyzer (Co-Kyoto,Japan).A sample of 20mg was housed in a small Pt–Rh crucible with a heating rate of 108C/min,using a -Al 2O 3as a reference sample.Infrared spectral analysis was carried out on some selected samples of hydrated pastes to provide additional information on the hydrated products.One milligram of the powder sample was ground with 99mg of potassium bromide in an agate mortar to produce a homogeneous mixture.The infrared spectral analysis was recorded from KBr-discs using Genesis-II FT-IR spectrometer in the range 300–4000cm À1.Fig.2.DTA of phosphogypsum and h -hemihydrate.Table 2Mix design of the investigated mixed of C 3A,h -hemihydrate,phospho-gypsum,Ca(OH)2and quartz (mass%)Mix mass%no.C 3A Ca(OH)2h -hemihydrate Phosphogypsum Quartz C.0551520010C.5551515510C.105515101010C.155********C.2055152010Table 1Chemical oxide composition of phosphogypsum (mass%)SiO 2Al 2O 3Fe 2O 3CaO MgO SO 3P 2O 5F ÀCl ÀL.O.I Phosphogypsum8.780.290.3532.130.0937.601.820.80–18.25M.M.Radwan,M.Heikal /Cement and Concrete Research 35(2005)1601–160816033.Results and discussion3.1.Chemically combined water contentsChemically combined water contents of the prepared pastes from different mixes of tricalcium aluminate,h -hemihydrate and phosphogypsum are depicted in Fig.3as a function of curing time up to 168h.Investigation of the results indicates that,the values of chemically combined water contents generally increase with the curing time from 6up to 168h.At early hydration period (6h),chemically combined water contents decrease with the phosphogypsum content;this is due to the impurities present in the phosphogypsum,such as P 2O 5,F Àand organic matter.As shown in Fig.3,the behavior of C.0,C.5and C.10,which contain 0,5and 10mass%phosphogypsum,respectively,is almost nearly the same.With an increase of the amount of phosphogypsum at the expense of h -hemihydrate in Mixes C.15and C.20(15and 20mass%phosphogypsum),the values of chemically combined water contents decrease at 6h.The presence of phosphogypsum decreases the rate of hydration of tricalcium aluminate during the first few hours.However,chemically combined water content shows sharp increase from 24up to 72h,which indicates an acceleration in the process of hydration.During the course of hydration reaction,there is a great tendency for the chemical reaction between C 3A phase and h -hemihydrate as well as phos-phogypsum in the presence of Ca(OH)2which already exists in each mix composition (15mass%)to give high and low forms of calcium sulphoaluminate,i.e.,C 3A d 3CaSO 4d 32H 2O and C 3A d CaSO 4d 12H 2O,respectively.In addition,C 3A phase will hydrate to form different calcium aluminate hydrate phases.However,the increase of the combined water contents of the hydrated pastes of C.15and C.20after 24h of hydration may be attributed to the enhancement of ettringite formation [18].Due to the relatively high solubility of h -hemihydrate compared with the raw gypsum,it was expected that the reaction between phosphogypsum and C 3A will proceed via lower rate than that between C 3A and h -hemihydrate;but as was found in the study,there is a great similarity in the rate of reaction of both materials used and C 3A which is connected with the expected acceleration effect of the impurities contaminated with phosphogypsum on the rate of its reaction with C 3A phase.The presence of impurities (F Àand/or P 2O 5)activates the formation of ettringite.Ettringite is less stable,which transformed to more stable phase (monosulphate)at longer hydration ages resulting to a decrease in the chemically combined water of these two mixes after 72and 168h.This result will be confirmed by investigating the samples by DTA and XRD in addition to the combined lime bined lime contentsIt was mentioned before that a fixed percent of Ca(OH)2(15mass%)was added to each mix to furnish a suitable condition for the formation of sulphoalumintes.As was mentioned before,the presence of Ca(OH)2maintain the same alkaline condition as in the case of OPC clinker and is incorporated in the hydration reaction of C 3A in the presence of CaSO 4.The lime was partially consumed during the reaction of C 3A on one side and on the other side with CaSO 4.The consumed lime content (combined lime)can be calculated and considered as an indication of the extent of hydration reactions to form the above mentioned phases,which formed within the five different mixes.These are graphically represented as a function of curing time and the amount of phosphogypsum substituted in Fig.4.It is well known that the reaction between CaSO 4and C 3A phase proceeds in the presence of Ca(OH)2in the reaction medium.Fig.4shows that at all curing ages,the combined lime slightly increases with the amounts of phosphogypsum.Mixes C.15and C.20that contain the higher proportion of phosphogypsum (15and 20mass%)have higher combined lime content than the other mixes.This indicates that there is a little acceleration effect on the hydration reaction of C 3A phase due to the presence of phosphogypsum,which confirms the results of combined water.This acceleration effect leads to the consumption of more lime as the amount of phosphogypsum increases,and increases the probability of the formation of C 4AH 13.3.3.Differential thermal analysisThe paste samples of all mix compositions hydrated for 7days have been investigated by DTA.The thermal effect on the DTA curves obtained for the hardened pastes are illustrated in Fig.5.Investigation of the DTA curves shows characteristic endotherms at about or around 130,225,310,425,515and 8258C,representing dehydration,dehydrox-ylation or calcination of residual ettringite,monosulphoa-Fig. 3.Chemically combined water contents of tricalcium aluminate hydrated as a function of curing time and phosphogypsum contents up to 20mass%.M.M.Radwan,M.Heikal /Cement and Concrete Research 35(2005)1601–16081604luiminate,C 3AH 6and C 4AH 13,Ca(OH)2and calcium carbonate.As can be seen from Fig.5,the endothermic peak at about 130–1408C,characterizing the dehydration of ettringite,is sharply diminished with the increase of the amount of phosphogypsum substituted for h -hemihydrate from Mix C.0to C.20.This means that the ettringite transformed to monosulphoaluminate.The strong endother-mic effect appears at about 2258C,characteristic of monosulphoaluminate.The endothermic shoulder at about 3108C is due to C 3AH 6.These peaks show slight increase with the phosphogypsum content.Ettringite is less stable than monosulphoaluminate;thus,it is transformed into monosulphoaluminate after 24h,which persisted up to 168h [19].The endothermic peak at 4258C illustrates the decomposition of C 3AH 6and C 4AH 13[12];this shoulder shows a little increase with phosphogypsum,which is confirmed later by XRD technique.As can be seen in the present paper,the main material in all mix compositions is C 3A which represents about 55mass%and the maximum amounts of both hemihydrate and phosphogypsum represent about only one third of the amount of C 3A;the maximum ratio at which the reaction between C 3A and CaSO 4is 1:1,which means that there will be an excess free C 3A phase that will be hydrated with the excess mixing water in the presence of Ca(OH)2added to form the C 4AH 13phase.During the hydration of the free excess C 3A,there will be a possibility for the formation of CAH 10,which is not a stable phase,and will be converted to the more stable C 3AH 6phase [13].The peak at 5258C represented the dehydration of residual hydrolime (Ca(OH)2).The intensity of the endo-therm due to residual hydrolime in the thermograms slightly varies as it is partially entered in the hydration reaction of C 3A in the presence of both gypsum and phosphogypsum.The last endothermic peak,which is located at 8358C,is attributed to the calcination of calcium carbonate present as contaminated by impurities with h -hemihydrate and/or by partial carbonization of the added hydrolime.By comparing Fig.2with Fig.5,it can be seen that the characteristic endotherms of both h -hemihydrate and phosphogypsum show endothermic peak located at 2008C,which was not detected in the DTA curves of the tested pastes shown in Fig.5.This indicates that nearly all of the amounts of h -hemihydrate and phosphogypsum were consumed in the hydration reaction of C 3A phase forming the sulphoaluminate phases as the maximum amount of both materials added represents only one third of the quantity of C 3A phase present in each mix composition.3.4.X-ray diffractionFig.6shows the XRD patterns of Mixes C.5,C.10and C.15hydrated for 72h.The patterns show the presence of ettringite,monosulphate,Ca(OH)2,quartz,C 4AH 13,C 4AH 19and C 3AH 6.The presence of finely ground quartz in the prepared mixes does not play any role in the hydration reaction but only affects ettringite crystallization [16].Quartz surfaces counteract the retardation of SO 42Àon the hydration of C 3A by presenting additional sites for ettringite crystallization or by influencing the nucleation of the hydration products.At early stages of hydration,the ettringite phase started to form with the consumption of lime and sulphate while thecombined water increases.As long as SO 42Àdiffused between the ettringite crystals towards C 3A,the ettringiteremains stable.If,however,no SO 42Àreaches the C 3A,ettringite is converted into monosulphate and C 4AH 19[16].It has been mentioned that the trisulphoaluminate (ettringite)in this system is less stable than monosulphoa-luminate;hence,it is transformed into monosulphoalumi-nate after 24h and it persisted up to 168h.As the content of phosphogypsum increases,the intensity of ettringitepeaksFig.5.DTA of tricalcium aluminate hydrated at 7days (168h)in the presence or absencephosphogypsum.Fig. bined lime content of tricalcium aluminate hydrated as a function of curing time and phosphogypsum contents up to 20mass%.M.M.Radwan,M.Heikal /Cement and Concrete Research 35(2005)1601–16081605decrease as a result of the transformation to monosulphate. The patterns also showed an increase in the intensities of different forms of calcium aluminate(C4AH13,C4AH19and C3AH6).The intensity of these forms of calcium aluminates increases with the content of phosphogypsum.This is due to the larger amounts of C3A(55%)compared with SO42Àcontent.In addition,the peak intensities representing the monosulphate increase with the prolongation of curing time and phosphogypsum content.The characteristic peaks of CaCO3were detected by XRD patterns.3.5.FT-IR spectroscopyFT-IR spectroscopy is one of the most powerful techniques normally used for molecular characterization. In particular,the FT-IR results have been used to resolve the hydroxyl bonds and to monitor the dynamics changes in the sulphate region during hydration reactions.In addition,the effect of atmospheric carbon dioxide on the hydration can be characterized.Fig.7shows FT-IR spectra of the hydrated samples of different mixes for6h.The spectral data are seen in three regions:the water region(N1000cmÀ1),the sulphate region(c1100–1160cmÀ1)and the region (b1000cmÀ1).The water regions give information about the mechanism of early hydration reaction.There are three bands in the range of3700–3100cmÀ1.Ca(OH)2gives a peak at3640 cmÀ1;ettringite has one at3420cmÀ1and a weaker one at 3600cmÀ1;and monosulphate has one at3100,3500 (broad),3540and3675cmÀ1.The broad band centered at 3400cmÀ1is due to symmetric and asymmetric(o1and o2) stretching vibration of O–H water molecule.Thewater Fig.7.FT-IR spectroscopy of hydrated C3A phase at6h in the presence or absence ofphosphogypsum.Fig.6.XRD patterns of Mixes C.5,C.10and C.15hydrated at168h(5,10and15mass%phosphogypsum);E,ettringite;M,monosulphoaluminate;CH, Ca(OH)2;C1,C4AH13;C2,C4AH19;C3,C3AH6;CC¯,CaCO3.M.M.Radwan,M.Heikal/Cement and Concrete Research35(2005)1601–16081606stretching region (c 3460–3440cm À1)becomes broader with the reaction time;this is due to the molecular water.In addition,it was found that the bending vibration of water can be seen at 1640cm À1.The ettringite phase is the main hydration product in this study at early ages.Upon hydration time,there is a change in sulphate absorption to a singlet,and the subsequent replacement of ettringite to monosulphate by a further return to doublet [13].The peaks located at 1120and 1180cm À1,which is due to o 3–SO 42À,supported the presence of ettringite and monosulphate.The peaks located at 1640and 1680cm À1were assigned to the deformation of water mode in these phases [20].The carbonate bands at 1420–1480cm À1arise from the atmospheric CO 2with the residual Ca(OH)2[21].The hexagonal hydrate and mono-carbonate were detected in spectra with split bands o 3–CO 32À(1416–1370cm À1)together with o 2–CO 32À(875cm À1)ando 3–CO 32À(712cm À1).The FT-IR spectra of C 2AH 8and C 4AH 13showed similarities,as hexagonal plate-type structure,usually over-lapped if more than one hexagonal aluminate coexist [22],but these were significantly different from the spectra of cubic hydrate (C 3AH 6).3.6.Scanning electron microscopyFig.8shows SEM of Mixes C.0and C.20,which contained 0and 20mass%phosphogypsum,respectively.The micrograph of Mix C.0shows very small amount of ill-crystallized fibrous-shaped ettringite in addition to hexag-onal crystals of monosulphate and C 4AH 13.The micrograph of Mix C.20shows a closer texture of hexagonal crystals.This is due to the presence of phosphogypsum impurities [23].4.ConclusionsFrom the above findings,it can be concluded that:(1)At early hydration period (6h),the chemicallycombined water contents decrease with the proportion of phosphogypsum.With the increase of the amount of phosphogypsum (15and 20mass%phosphogyp-sum),the values of chemically combined water contents decrease at 6h.(2)The combined lime slightly increases with theincrease of amounts of phosphogypsum in the mix.(3)DTA shows that the endothermic peak at about 130–1408C,which characterizes the dehydration of ettringite,is sharply diminished with the increase of the amount of phosphogypsum;that is,ettringite transformed to monosulphoaluminate.It has been mentioned that the trisulphoaluminate (ettringite)in this system is less stable than monosulphoaluminate;thus,it is transformed into monosulphoaluminate after 24h and persisted up to 168h.(4)The XRD patterns showed the increase in theintensities of monosulphate and different forms of calcium aluminate (C 4AH 13,C 4AH 19and C 3AH 6with phosphogypsum content).(5)Phosphogypsum reacts with C 3A in the presence ofCa(OH)2forming sulphoaluminate hydrates,which are responsible for setting regulation in cementitious system.The mechanism of the hydration process of C 3A phase in the presence of phosphogypsum proceeds in a similar manner to that with h -hemihydate.References[1]P.Yan,W.Yang,X.Qin,Y .You,Microstructure and properties of thebinder of fly ash–fluorogypsum–Portland cement,Cem.Concr.Res.29(3)(1999)349–354.[2]P.Yan,Y .You,Studies on the binder of fly ash–fluorgypsum–cement,Cem.Concr.Res.28(1)(1998)135–140.[3]M.Singh,M.Garg,Cementitious binder from fly ash and otherindustrial wastes,Cem.Concr.Res.29(3)(1999)309–314.[4]N.Bhanumatidas,N.Kalidas,NCB International seminar on cementand building materials.Science and Technology,New Delhi,India.(1996)3,55.Fig.8.SEM of tricalcium aluminate hydrated at 7days of Mixes C.0and C.20.M.M.Radwan,M.Heikal /Cement and Concrete Research 35(2005)1601–16081607[5]M.Singh,M.Garg,Relationship between mechanical properties andporosity of water-resistant gypsum binder,Cem.Concr.Res.26(3) (1996)449–455.[6]M.Singh,M.Garg,S.S.Rehsi,Purifying phosphogypsum 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