偏高岭土地聚物制备条件及其水化过程

研究了青岛高岭土制备地聚物的最佳条件和地聚物的水化过程。重点考察了水灰比、碱激发剂掺量、水玻璃模数等因素对地聚物抗压强度的影响。结果表明：以高岭土煅烧得到的偏高岭土为原料制备地聚物,当水灰比为 ０.３５、碱激发剂掺量为 ２１％、水玻璃模数为 １.４时,地聚物具有较高的强度。由此制备的地聚物试块在 ５０℃下用保鲜膜包裹养护 ９ｄ再自然养护 １９ｄ,其抗压强度为 ７１ＭＰａ。通过 ＸＲＤ、ＳＥＭ对地聚物的水化过程进行了研究,揭示了地聚物不同水化时间的微观结构变化,结果表明：地聚物在水化过程中,先脱水缩聚生成小颗粒地聚物前驱体,然后进一步生成相对较大的分子,最后连接成网状结构,形成致密结构;其水化产物主要是网状无定型的硅铝凝胶,对应的 ＸＲＤ衍射区域为 ２０°～３０°。     

混凝土中水泥水化反应放热模型及其应用

大体积混凝土结构水化热温度场分析的关键是混凝土中水泥水化反应放热模型的确定。基于化学反应动力学原理，提出了一种物理意义明确，考虑了温度和化学反应物浓度对化学反应速率影响的混凝土中水泥水化反应放热模型，并将其应用于有限元分析。算例分析表明，该模型能很好地拟合了混凝土绝热温升的实测数据，较精确地预测了在不同浇筑温度下混凝土绝热温升的变化规律。     

早强复合型水泥混合材料的研制

部分固体废弃物在单独作混合材时,对水泥的早期强度(3 d)有不利影响,从而有可能影响水泥的使用.为此,选取了粉煤灰、矿粉、石灰石粉、赤泥4种固体废弃物,先将它们以5%,10%,15%的比例单独取代水泥熟料,在此基础上,固定混合材的总比例为15%,将它们混掺,且其中赤泥的比例固定为5%,研究了它们对水泥3,28 d强度的影响.试验结果表明,10%矿粉和5%赤泥以及粉煤灰、矿粉、赤泥各占5%时,组成的混合材,不仅能提高水泥28 d的强度,而且还能提高其3 d的强度.     

高强混凝土的配制与基本性能

通过砂、石骨料的级配优化 ,采用 52 5 #普通硅酸盐水泥和复合型高效减水剂 ,配制出实用的75N·mm- 2 ～ 85N·mm- 2 高强混凝土 ,研究了水泥用量、水灰比、砂率、高效减水剂掺量对混凝土拌和性能、力学性能的影响规律 ,为活性矿物掺合料匮乏地区的高强混凝土配合比设计和工程应用提供了科研依据     

高强无腹筋梁抗剪承载力分析

收集了国内外134个集中荷载下高强无腹筋简支梁的抗剪试验数据,将实测承载力与中国国标GB50010-2010和美国的ACI318-08的预测结果进行了对比,结果表明:2国标准对于计算高强无腹筋梁安全度不够。GB50010-2010预测大剪跨比、有效截面高度偏大,纵筋率偏小的高强钢筋混凝土构件,可靠度偏低。     

钢骨高强混凝土叠合柱压弯承载力的计算

通过数值计算,分析了参数叠合比和轴压比对钢骨高强混凝土叠合柱压弯承载力的影响;介绍了我国钢骨混凝土结构设计规程中钢骨混凝土柱的承载力计算方法;在此基础上,建议了钢骨高强混凝土叠合柱压弯承载力的实用设计方法,并与数值计算结果进行了比较。     

纤维高强粉煤灰混凝土劈拉强度试验研究

针对掺加纤维可改善高强混凝土的受拉性能特点,进行纤维粉煤灰高强混凝土的立方体劈拉试验研究。试验参数主要有纤维类型、纤维形状、纤维含量。试验结果表明：随纤维掺量的增大,纤维高强混凝土劈拉强度总体上呈增大趋势;扁头型和弓型钢纤维对混凝土劈拉强度的增强作用最明显,而合成纤维对混凝土劈拉强度的增加作用很小;掺入钢纤维对高强混凝土劈拉强度与抗压强度的比值明显提高。     

Effect of superplasticizers on the early age hydration of sulfoaluminate cement

The effects of two types of superplasticizers on the properties of CSA cement pastes during early hydration were studied. The influences of two types of superplasticizers on the properties of cement pastes, including the normal consistency, setting time, fl uidity, and compressive strength, were investigated by using various methods. The hydration products of the cement pastes cured for 1 day and 3 days were studied by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. The results show that the PCE type superplasticizer retards the early age hydration while the FDN type superplasticizer accelerates the early age hydration of the CSA cement. Both types of superplasticizers have no infl uence on the further hydration of CSA cement, confi rmed by the calorimeter tests as well. The ultrasonic pulse velocity measurements were used to probe the influence of two types of superplasticizers on the hydration of CSA cement pastes at a high water-cement ratio（0.45）. The results show that the PCE type superplasticizer retards the early age hydration of the CSA cement while the FDN type superplasticizer has little infl uence on the early age hydration of the CSA cement.     

型钢高强混凝土柱抗剪承载力的试验研究

通过20个混凝土强度为65.3—84.9 MPa的型钢高强混凝土柱在轴力和水平荷载共同作用下的试验,对型钢高强混凝土柱的抗剪性能进行了研究.试验主要考虑剪跨比、轴压比、配箍率和混凝土强度四个参数对构件抗剪性能的影响.由试验得到了水平荷载下型钢高强混凝土柱的破坏形态,分析了剪跨比、轴压比、配箍率和混凝土强度对构件抗剪承载能力的影响,提出了型钢高强混凝土柱抗剪承载能力的计算公式,公式的计算结果与试验结果符合较好.     

NMR research on cement clinker and its structures in early age hydration

Clinker has long been regarded as a critical factor for cement hydration and solidification.α-C2S and β-C2S in 2CaO·SiO2(C2S) phase and C3S Monoclinic 1(C3S M1) and C3S Monoclinic 3 (C3S M3) in 3CaO·SiO2 (C3S) phase were clearly recorded in the 29Si MAS NMR spectra.The content of C3S phase in the clinker deduced from the fine peak analysis coincides with the phase quantification analysis calculated by the Taylor-Bogue method based on XRF,which also accords to the statistical data in industrial production.NM...     

废弃混凝土做不同水泥强度掺合料的试验研究

为了使废弃混凝土充分循环利用,通过废弃混凝土磨细粉XRD图谱分析其作为水泥的混合材的可行性。试验表明,用掺量为10%废弃混凝土磨细粉可以生产出标号为32.5的水泥,碱性激发剂对废弃混凝土的激发效果不明显。     

Experimental investigation on strength and deformation of plain high-strength concrete under multiaxial stress state

To investigate the strength and deformation behavior of plain high-strength concrete (HSC) under multiaxial stress states,a large static-dynamic true triaxial machine was employed,and multiaxial tests were performed on 100 mm×100 mm×100 mm cubes concrete specimens.Friction-reducing pads were three-layer plastic membranes with glycerine in-between for the compressive loading plane.The tensile loading plane of concrete samples was processed by attrition machine,and then the samples were glued up with the loading plate with structural glue.Failure modes of specimens were described.The principal static compressive strengths,strains at the peak stress and stress-strain curves were measured,and the influence of stress ratios on them was analyzed as well.Experimental results show that the ratio of the compressive strength σ3f over the uniaxial compressive strength fc depends on brittleness-stiffness of concrete besides stress state and stress ratios.The formula of Kupfer-Gerstle’s and Ottosen’s failure criterion for plain HSC under biaxial compression and multiaxial stress state is proposed respectively.     

利用水泥制备高强透水性混凝土

在已有研究成果的基础上,利用普通硅酸盐水泥、添加适宜外加剂、采用特殊生产工艺和成型方法,研制出抗压强度高达C50的透水性混凝土,满足车行路面要求,其总孔隙率、连通孔隙率、渗透系数亦满足规范《混凝土路面砖》JC/T446-2000要求。     

偏高岭土高性能混凝土的轴压应力-应变关系

采用美国产MTS试验机,研究了掺偏高岭土(Melakaolin,MK)的混凝土轴压应力-应变关系．试验结果表明,随着MK掺量的增加,混凝土的抗压强度随之提高,特别是早期强度提高更为显著．弹性模量略有提高,但幅度明显小于强度提高值．混凝土的韧性得到改善．此外,MK对混凝土的流动性影响较小,且能显著改善粘聚性和保水性．因此,偏高岭土是一种优异的高强高性能混凝土掺合料．     

早强混凝土脱模强度的试验研究

为满足Fpccp管生产及施工的需要,围绕水胶比、外加剂的掺量及蒸养参数(静养时间、升温速度、恒温时间、恒温温度及降温时间)等对C40早强混凝土脱模强度的影响因素进行了系统的试验研究,得到了满足"6h脱模强度不低于20MPa"的早强混凝土配合比(水胶比0.34、减水剂掺量1.1%、速凝剂掺量1.8%)及蒸养制度(静养时间10～30min、升温速度20～22℃/h、恒温时间120～180min、恒温温度65℃、降温时间10～40min).可加快模具周转速度,缩短生产周期,提高生产效率,节约生产成本,为Fpccp管生产及施工提供理论依据和技术支撑.     

水泥混凝土强度推定的多参数模型应用研究

为了提高超声法评定水泥混凝土抗压强度的精度,开展了水泥混凝土的多参数强度推定模型的应用研究。在声波传播过程中,由于混凝土物性以及检测距离的变化,除声速以外的其它声参数也会随之而变化,这种变化也应被考虑到强度推定的数学模型中。为此,通过理论分析建立相应的多参数数学模型,分别是声速、衰减系数Ⅰ与抗压强度,声速、衰减系数Ⅱ和抗压强度,及声速、衰减系数Ⅰ、衰减系数Ⅱ与抗压强度之间的3参数数学模型关系。与单参数模型的相关系数对比表明,多参数强度推定模型相关系数较高。     

Effects of LiAl-layered double hydroxides on early hydration of calcium sulphoaluminate cement paste

As a 3D micro-nano material, layered double hydroxides have been widely used in many fields, especially for reinforced composite materials. In this paper, LiAl-LDHs was obtained by a hydrothermal method. In order to investigate the effects of LiAl-LDHs on the early hydration of calcium sulphoaluminate (CSA) cement paste, compressive strength, setting time and hydration heat were tested while X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scaning electron microscopy (SEM) and differential scanning calorimetry (DSC) analysis were employed. The results indicated that LiAl-LDHs could significantly improve the early compressive strength and shorten the setting time of calcium sulphoaluminate cement paste with 3wt% concentration. Besides, the hydration exothermic rate within 5 h was accelerated with increasing LiAl-LDHs content. Moreover, the addition of LiAl-LDHs did not result in the formation of a new phase, but increased the quantity of hydration products providing higher compressive strength, shorter setting time and denser microstructure.     

甲酸钙对水泥浆体抗压强度、水化及孔结构的影响

研究了甲酸钙对普通硅酸盐水泥浆体和硅酸盐水泥浆体抗压强度的影响,采用XRD、压汞法和灼烧法,测试了甲酸钙对水泥浆体水化产物组成、孔结构及化学结合水的影响。结果表明：甲酸钙能加速水泥的水化,促进Ca（OH）2的生成,提高水泥浆体的水化程度;甲酸钙能明显改善水泥浆体的孔结构,减少孔隙率和细化孔径;甲酸钙对P·O42．5普通硅酸盐水泥浆体早期强度的提升要比对P·152．5硅酸盐水泥的效果好。     

水泥矿物水化率的测定与特性分析

水化程度和水化速度是进一步研究水泥矿物化学成分的转化及水泥基建筑材料耐久性的重要参数.通过测定不同水化龄期的水泥试样的化学结合水量可以间接测定水泥水化速度,即水化率.实验中找出了一些容易影响测定化学结合水量的因素和问题,并对水泥新鲜烧失量和化学结合水量的测定方法中关键的细节操作做了相对合理的处理,同时也对不同配方水泥试样同一龄期的水化情况进行了测试.通过对实验数据进行综合分析,找出了不同配方水泥试样的水化规律.     

The Pore Structure and Hydration Performance of Sulphoaluminate MDF Cement

1　IntroductionReducingporositycouldimprovethestrengthofma terials ,butitisnotenoughthatthechangeofthestrengthofthematerialsisonlysubjectedtothechangeofporosi ty .Thereforetheporedistributionconceptisintroduced .Weeventhinkthattherelationbetweentotalporos…