掺合料对过硫磷石膏矿渣水泥早期性能的影响

研究了矿物掺合料偏高岭土、硅灰、硫铝酸盐水泥和外加剂水玻璃对过硫磷石膏矿渣水泥凝结速率、早期强度等早期性能的影响规律,并通过XRD、SEM等对过硫磷石膏矿渣水泥的水化及结构发展进行了研究。结果表明,在过硫磷石膏矿渣水泥中掺加水玻璃和偏高岭土,能显著提高该水泥的凝结速率和早期强度,3d、7d、28d抗压强度分别达到17MPa、32MPa、46MPa。     

水泥基复合胶凝材料改性聚合物修补砂浆的试验研究

针对硫铝酸盐水泥基修补材料凝结时间快、抗折强度倒缩等问题,提出以普通硅酸盐（PO）- 硫铝酸盐水泥（SAC）复合改性聚合物快速修补材料性能,探究 PO-SAC 复合胶凝体系对聚合物修补砂浆的新拌性能和力学性能的影响,并且进一步研究了复合体系对砂浆界面粘结性能的影响,采用 SEM 分析解释宏观性能变化。结果表明：当 PO 占复合胶凝体系比例达 90% 时,聚合物修补砂浆的凝结时间相比 SAC 明显延长,满足修补需求;流动性能良好,砂浆呈现微膨胀性,28 d 时的收缩率为 -3.21×10-4;早期强度高,1 d 抗压强度达到 26.1 MPa,且后期抗压、抗折强度增长幅度大;界面粘结性能优异,28 d 粘结强度可达到 4.4 MPa。随着PO 的掺入,复合胶凝体系的水化产物钙矾石（AFt）会逐渐减少,砂浆微观形貌不致密,不利于水泥浆体早期强度和收缩的发展。     

装配式建筑套筒灌浆料早期强度与流动性的试验研究

为了提高套筒灌浆料的早期强度和流动性,分别将早强剂掺量、减水剂掺量和硫铝酸盐水泥掺量作为不同变量来进行试验,探究这3个因素对套筒灌浆料早期强度(1 d和3 d抗压强度)和流动性的影响规律。结果表明：适当掺量的早强剂和硫铝酸盐水泥会使早期抗压强度增大,但同时会使流动度减小;在一定范围内,3 d抗压强度和流动度随减水剂掺量的增加而增大,1 d抗压强度随减水剂掺量的增加而减小;当早强剂掺量0.3%、减水剂掺量0.8%、硫铝酸盐水泥代替普通硅酸盐水泥比例为20%时,套筒灌浆料的工作性能和早期抗压强度综合最优。     

磷石膏/矿粉复合过硫胶凝材料的制备研究

通过研究磷石膏、硫铝酸盐水泥熟料、碱激发剂等组分掺量对过硫胶凝材料体系物理力学性能的影响,借助XRD、SEM等微观测试手段对水化产物及机理进行分析探讨,确定了过硫胶凝材料组成的最佳配合比。结果表明:5%的硫铝酸盐水泥熟料、30%的磷石膏、63%的矿粉、2%的碱激发剂制备出的磷石膏/矿粉复合过硫胶凝材料标准稠度用水量为30.8%,初凝时间为312min,终凝时间为514min,3d抗压强度可达13MPa,28d抗压强度超过48MPa。微观分析表明,在该配比下制备的过硫胶凝材料主要水化产物为钙矾石和C-S-H凝胶,水化28d时钙矾石生成量较大,结构较为致密,强度大幅度提高。     

ECC型自保温干混砂浆的制备与性能表征1

在普通干混砂浆中掺加木质素纤维,且用膨胀珍珠岩颗粒等量代替普通细集料砂,获得自保温干混砂浆样品,研究其物理力学性能、热学性能及收缩性能等。结果表明：加入占胶凝材料质量0.3%的木质素纤维,能显著改善自保温砂浆硬化后的力学性能,尤其是抗折强度;用膨胀珍珠岩替代砂,膨胀珍珠岩的体积分数小于15%时,能提高含纤维硬化样品的28 d抗压强度,大于15%时,样品的28 d抗压强度会降低,为15%时,砂浆试样硬化后的28 d抗压强度为38 MPa,抗折强度为6.1 MPa;另外,当样品中膨胀珍珠岩体积分数为20%,含胶凝材料质量0.3%的木质素纤维,其硬化后的导热系数仅为基准砂浆样品的1/3。     

固硫灰泡沫混凝土的基材研究

以熟料(30%)-固硫灰(70%)做基体,研究了在不同养护方式下,生石灰、铝酸盐水泥单掺及复掺时对基体强度、凝结时间、膨胀性能的影响。结果表明,在熟料-固硫灰系统中加入生石灰可激发固硫灰活性、加快浆体稠化,提高后期强度并增加膨胀。单掺2%铝酸盐水泥的基体强度最高,但当与生石灰复掺时,基体凝结时间会进一步缩短且强度降低,但膨胀增加显著。蒸养有利于基体强度发展并能有效限制膨胀,其膨胀率约为标养的20%。在生石灰掺量为8%,铝酸盐水泥掺量为2%和60℃蒸气养护1d的条件下,可以制备出容重为393kg/m3,强度2.1MPa且性能合格的固硫灰泡沫混凝土。     

ECC型自保温干混砂浆的制备与性能表征

在普通干混砂浆中掺加木质素纤维,且用膨胀珍珠岩颗粒等量代替普通细集料砂,获得自保温干混砂浆样品,研究其物理力学性能、热学性能及收缩性能等.结果表明:加入占胶凝材料质量0.3％的木质素纤维,能显著改善自保温砂浆硬化后的力学性能,尤其是抗折强度;用膨胀珍珠岩替代砂,膨胀珍珠岩的体积分数小于15％时,能提高含纤维硬化样品的28d抗压强度,大于15％时,样品的28 d抗压强度会降低,为15％时,砂浆试样硬化后的28 d抗压强度为38 MPa,抗折强度为6.1 MPa;另外,当样品中膨胀珍珠岩体积分数为20％,含胶凝材料质量0.3％的木质素纤维,其硬化后的导热系数仅为基准砂浆样品的1/3.     

稻壳灰改性铝酸盐水泥的试验研究

针对铝酸盐水泥中后期强度倒缩的问题,进行了稻壳灰作为外掺料改性铝酸盐水泥的试验研究。分别测试了稻壳灰对铝酸盐水泥抗压强度、抗折强度、泌水率及渗透率的影响,并通过XRD分析探讨了稻壳灰的作用机理。结果表明:适量的稻壳灰不仅可以提高铝酸盐水泥的早期强度,还可以有效改善其中后期强度,稻壳灰掺量以15%为佳;稻壳灰的比表面积巨大,其表面可有效吸附大量水分子,改善了铝酸盐水泥的泌水性;稻壳灰的填充效应使硬化浆体中的连通孔隙数量减少,进而改善了铝酸盐水泥的渗透性;稻壳灰活性被激发后可与水化产物发生反应,削弱了发生在水化反应中后期的晶相转变作用,避免了硬化浆体的中后期强度倒缩。     

聚合物对发泡水泥制品孔结构和性能影响

以快硬硫铝酸盐水泥作为胶凝材料,干密度为200 kg/m3的发泡水泥为对象,研究乳液和胶粉对发泡水泥孔隙率、孔径分布、孔径大小和强度的影响.结果显示:随着聚合物掺量的增加,发泡水泥制品的孔隙率不随聚合物掺量的增加而发生变化,气孔的孔径逐渐变小,强度不断增大.当乳液和胶粉外掺量分别为2.5%时,发泡水泥28d的抗压强度、抗折强度和垂直表面拉伸强度分别增加8%、13%、28%和5%、10%、25%.     

粉煤灰对硅酸盐水泥-铝酸盐水泥-石膏三元体系性能的影响

硅酸盐水泥-铝酸盐水泥-石膏三元体系具备明显的快硬、快凝、补偿收缩的性能,在该体系中掺入粉煤灰可以部分取代水泥降低成本,改善三元体系的工作性能,满足不同修复工程的需要.研究了不同掺量粉煤灰对三元体系的水化历程的影响,测试了浆体流动度、凝结时间以及硬化砂浆的强度和体积变形性能,并用X-射线衍射分析(XRD)对微观结构进行分析.结果表明:粉煤灰可以提高三元体系的流动性,并且延长其经时损失,当掺量大于20%时,三元体系的凝结时间明显延长.随着粉煤灰掺量的增加,硬化砂浆的强度降低,早期体积膨胀率减小但后期不收缩.综合考虑,粉煤灰的掺量控制在20%~30%,可以满足实际工程的需要.     

Durability of alite-calcium barium sulphoaluminate cement

The durability of the cement was mainly studied. Under 1.0 MPa of hydraulic pressure for 8 hours, water could penetrate completely through the sample made by portland cement, but could not penetrate through that by alite-barium sulphoaluminate cement. Under the condition of freezing and thawing cycle, the loss ratio of compressive strength of the cement was only about 17.3% at curing 28 d ages, but the loss of portland cement was as high as 29.5%. Alite-calcium barium sulphoaluminate cement also has an excellent resistance to sulfate attack. The coefficients of resistance to sulfate attack of the cement exceeded 1.0. Meanwhile, the composition and microstructure of the hardened paste of alite-calcium barium sulphoaluminate cement were analyzed by XRD and SEM.     

MODIFICATION THE CEMENTIOUS MATERIAL OF ULTRA-HIGH-STRENGTH SLEEPER CONCRETE

This paper presents investigation results on the natural ultra-fine mineral flour of crystalline silica fume (CSF) and porous quartz sand stone (PQSS) which can modify cement mortar strength under hydrothermal synthesis reaction (HSR) in the autoclave-cured condition. The replacement of cement by CSF and PQSS can signifi cantly increase the flerural and compressive strength. which reach 22MPa and 150MPa respectively, and decrease the porosity of the cement mortar. The ratio of fine aggregation, standard sand to cementious material has significant influence on the mortar strength. The mechanisms involved in cement and natural mineral flour and the HSR are presented. CaO/SiO_2 ratio ranges from 3.20 to 1.11. the main hydrate phase is C_2SH and there is not Tohermorite through X-Ray diffraction qualitative analysis. The new and ultra-high strength cementbms material as basic material of sleeper concrete can be used in prestressed reinforcement sleeper concrete.     

Effect of coal gangue with different kaolin contents on compressive strength and pore size of blended cement paste

The effects of activated coal gangue on compressive strength, porosity and pore size distribution of hardened cement pastes were investigated. Activated coal gangue with two different kaolin contents, one higher and one lower, were used to partially replace Portland cement at 0%, 10%, and 30% by weight. The water to binder ratio（w/b） of 0.5 was used for all the blended cement paste mixes. Experimental results indicate that the blended cement of activated coal gangue mortar with higher kaolin mineral content has a higher compressive strength than that with lower kaolin mineral content. The porosity and pore size of blended cement mortar were significantly affected by the replacement of activated coal gangue.     

Influence of ultra-fine fly ash on hydration shrinkage of cement paste

1INTRODUCTION Hydrationshrinkageisalsoknownaschemicalshrinkage[1].Thesolidvolumeincreasesafterce menthydrating,buttheabsolutevolumeofcementwatersystemreduces.Usuallythetotalamountofvolumeshrinkageofcementwatersystemis7%9%[1,2].Withthedevelopmentofthetechno logyofcementandconcrete,concretewithhighstrengthandhighperformanceisthedevelopingtendencynow.However,nowadays,comparedwithordinaryconcrete,thehydrationshrinkageofhighperformancecementconcreteincreasesobvi ouslybecauseoftheaccelerationof…     

UFA水泥基材料早期自干燥及自收缩研究

基于水泥石孔隙理论对超细粉煤灰（Ultra-fine fly ash，简称UFA）水泥基材料的早期自干燥效应进行了理论分析及试验研究。在此基础上，采用改进的混凝土自收缩试验装置对UFA混凝土的早期自收缩变形进行了测试。结果表明，相比于基准水泥石，UFA水泥石内部自干燥程度大大降低；且随着UFA的掺入，混凝土早期水化反应的有效水灰比增大，自收缩变形随之减小，进一步证明水泥基材料早期内部孔隙的自干燥效应与混凝土的早期自收缩变形具有较好的相关性。     

Hydration mechanism of sulphoaluminate cement

The feasibility of sulphoaluminate cement (SAC) utilization in support mortar was studied. Setting time and strength of as-received sulphoaluminate cement (SAC) paste were examined, hydration kinetics behavior was determined through Isothermal Calorimeter, and hydration mechanism was investigated by X-Ray diffraction analysis (XRD) and field emission scanning electron microscopy analysis(FSEM). Results showed that as-received SAC contained 61% of anhydrous calcium sulfate (3CA·CaSO4) and dicalcium silicate (C2S). The strength after 1 day or 3 days grew to 68.6% or 85.7% of that after 28 days respectively, while most of hydration heat was released within 1 day. The emergency of three exothermic peaks at acceleration stage was found and hydration kinetics model was established choosing the terminal time of the first exothermic peak at accelerating stage as the beginning of accelerating stage. XRD analysis suggested that large amount of ettringite (AFt) was produced at early age and FSEM observation revealed that ettringite (AFt) formed in sulphoaluminate cement (SAC) paste was characterized of different morphology which was proved to be caused by different ion concentrations.     

Influence of CG With High Content of Metallic Particles as a Cement Admixture on Cement Strength

1　IntroductionCopperresidueisanindustrialby productdis chargedbycopperrefineries ,butitusuallycontainssomeusefulmetals .Forexamplecopperresiduecontains 4 %to5 %copper ,1.0 1g tgold ,2 4g tsilverand 4 2 %magne tite ,alltheseexceedthecontentforacomprehensiveutili zation .Inordertoextracttheseusefulmetals ,thecoolingtechnologyofremovingresidueisintroducedbyslowlycooling (4 8h)sothatsomemetallicionsgrow .Afteronemoreflotationforcopperandmagneticbyextractionofiron ,thedischargedresidueiscalledcopp…     

Properties and Acceleration Mechanism of Cement Mortar Added with Low Alkaline Liquid State Setting Accelerator

Low alkaline liquid state setting accelerator(LSA) for Portland cement was prepared in laboratory from aqueous solution of several inorganic sulfate salts and some organic chemical substances. Properties of cement with addition of LSA relating to its setting time and strength development as well as its resistance to sulfate attack for short and long term exposure were experimentally examined. The experimental results showed that 5%-7% addition of LSA significantly accelerated the initial and final setting of Portland cement in the presence or absence of the blending of mineral admixtures, the initial and final setting time being less than 3 min and 6 min respectively. Meanwhile, the early 1 day curing age compressive strength increased remarkably by 20%, while the late 28 th day curing age compressive strength remained almost unchanged as compared with that of the reference accelerator free cement mortar specimen. Furthermore, mortar specimens of cement added with LSA and exposed to 5% Na2SO4 solution showed their excellent resistance to sulfate attack, with their short and long term curing age resistance coefficient to sulfate attack being around 1.04 to 1.17, all larger than 1.0. XRD analysis on hardened cement paste specimens at very early curing ages of several minutes disclosed the existence of more ettringite in specimens added with LSA than that of the reference specimens, meanwhile SEM observation also revealed the existence of well crystallized ettringite at very early hydration stage, suggesting that the accelerated setting of Portland cement can be attributed to the early and rapid formation of ettringite over the whole cement paste matrix due to the introduction of LSA. MIP measurement revealed that hardened cement paste specimens with the addition of LSA presented less medium diameter pores, more proportion of small pores and less proportion of large capillary pores, which is in a very good coincidence with the improvement of strength development of cement mortars added with LSA.     

亚硝酸钠对硫铝酸盐水泥石孔结构及强度影响的研究

本文主要研究了亚硝酸钠对硫铝酸盐水泥石孔结构及强度的影响．结果表明：（１）亚硝酸钠具有明显改善硫铝酸盐水泥石孔结构的作用．（２）亚硝酸钠不仅提高硫铝酸盐水泥正温强度，而且大幅度提高其负温下强度．     

利用污水厂污泥配料煅烧水泥熟料研究

通过生料易烧性试验、水泥熟料矿物岩相分析、XRD、SEM、水泥胶砂强度试验等，对利用污水厂污泥代替部分粘土配料煅烧硅酸盐水泥熟料的过程，并对制备熟料的微观特征进行了研究。结果表明：污水厂污泥代替部分粘土烧制的水泥熟料，其矿物结构与常规的硅酸盐水泥熟料完全相同，且由污泥配料煅烧的熟料烧成温度有降低的趋势；其水泥水化和凝结、硬化过程与常规硅酸盐水泥完全相同；其水化产物结构与常规硅酸盐水泥完全相同；水泥胶砂强度达到50．0MPa。