超细矿渣粉对硅酸盐水泥性能和微观结构的影响

通过掺入不同量的超细矿渣粉,研究其对普通硅酸盐水泥凝结时间、标准稠度用水量以及水泥胶砂流动性和强度的影响。结果表明,水泥浆体的初凝、终凝时间在矿渣粉掺量为5%(质量分数,下同)时有所缩短,而随着超细矿渣粉掺量的增加,初凝时间都有所延长,在掺量为20%时初凝时间最长。然而终凝时间的变化不大,只有掺量为30%时稍有延长;水泥的标准稠度用水量先减少后增加,在掺量为20%时最小;随着超细矿渣粉掺量的增大,水泥胶砂的各龄期抗折强度、3d抗压强度不断提高,7d、28d抗压强度在掺量为20%时达到最大值,之后有所降低。掺入超细矿渣粉后,能通过填充以及与水泥水化产物氢氧化钙发生反应,使水泥中氢氧化钙含量明显降低,水泥微观结构更加密实。     

电阻率法研究引气剂对水泥浆体化学收缩及氯离子渗透性的影响

研究了引气剂对硅酸盐水泥浆体的电阻率、化学收缩、物理力学性能及氯离子渗透性的影响。结果表明,掺入引气剂使水泥浆体的流动度增大,凝结时间延长,早期水化速率加快,化学收缩增大。水泥浆体的电阻率在凝结前随着引气剂掺量的增加而增大,在硬化后则随着掺量的增加而减小。在28d龄期时,0.04%掺量内的引气剂对硬化浆体的抗压强度影响较小,其强度损失率低于5%,氯离子迁移系数随掺量的增大而减小。随引气剂掺量的变化,水泥浆体的电阻率与化学收缩、抗压强度和氯离子迁移系数均存在很好的定量关系。通过水泥浆体的电阻率发展曲线可以预测其化学收缩、强度与氯离子渗透性的变化规律。     

基于溶胶凝胶法改性的硅藻土对水泥基材料性能的影响

采用溶胶凝胶法对硅藻土进行改性,然后研究改性前后的硅藻土对水泥净浆(标准稠度用水量、凝结时间)及砂浆性能(力学性能、调湿性能)的影响。研究结果表明:(1)经改性后的硅藻土比表面积由初始的2.76m~2/g增大到158.52m~2/g,平均孔径由初始的3.82nm减小到1.41nm。(2)改性前后的硅藻土水泥净浆标准稠度用水量均高于纯水泥的标准稠度用水量,且随着硅藻土掺量的增加而逐渐增大;随着改性前后硅藻土掺量的增加,水泥初凝时间延长,终凝时间缩短。另外,在硅藻土掺量相同的条件下,改性硅藻土时凝结时间较原状硅藻土水泥凝结时间短。(3)改性后硅藻土的水泥砂浆强度较原状硅藻土的水泥砂浆高;随着改性前后硅藻土掺量的增加,水泥砂浆的强度均逐渐降低,而水泥砂浆吸、放湿率逐渐增大。另外,改性前后的硅藻土掺量相同时,改性后硅藻土的水泥砂浆吸、放湿率大于改性前的硅藻土水泥砂浆的吸、放湿率。(4)X射线衍射(XRD)和扫描电镜(SEM)分析结果表明,改性硅藻土的水泥砂浆较原状硅藻土的水泥砂浆有更多的水化产物,且硬化体结构更加致密。     

粉煤灰、石灰石粉复掺对水泥净浆工作性能的影响

通过检测水泥净浆流动度和Marsh时间,研究了不同掺量粉煤灰与石灰石粉对水泥浆体的工作性能的影响。结果表明,粉煤灰单掺掺量为20%的水泥浆体工作性能最优,单掺石灰石粉的水泥浆体随着掺量增加流动度呈线性增长;复掺掺量分别为20%、30%,粉煤灰和石灰石粉等量时,水泥浆体工作性能最好;通过对水泥、粉煤灰和石灰石粉的粒径分析,从微观角度分析了不同级配的水泥浆体的工作性能。     

盾构废弃泥沙再生制备高性能注浆材料的试验研究

利用盾构施工产生的废弃泥沙与水泥复合制备了一种高性能环保型注浆材料.研究了水固比、砂胶比、减水剂掺量对注浆料稠度、流动度、凝结时间、结石率、泌水率、抗压强度等性能的影响.结果表明:随着水固比增大,注浆料的初始稠度、凝结时间、流动度均增大,而结石率、抗压强度下降.随着砂胶比增大,注浆料的初始稠度、流动度均减小,而凝结时间延长.掺入聚羧酸高性能减水剂后,注浆料的工作性能显著提升.优选的配合比为:水固比0.45,砂胶比3:1,减水剂掺量2‰.相应注浆材料的技术指标为:流动度164 mm,初始稠度118 mm,凝结时间1035 min,结石率95.7％,泌水率2.4％,3 d抗压强度12.0 MPa.     

天然火山灰-水泥-粉煤灰复合浆体流变性能

采用C-LTD80 QC型旋转粘度计研究了天然火山灰-水泥-粉煤灰复合浆体的流变行为,分析了天然火山灰掺量对浆体屈服应力、塑性粘度以及触变性的影响,并采用Zeta电位仪探索其作用机理。结果表明：天然火山灰-水泥-粉煤灰复合浆体流变可分区段用Bingham模型及Herschel-Bulkley模型模拟;天然火山灰粒径分布跨度大,颗粒形状不规则,且密度小于水泥,等质量代替会增加浆体固相体积分数;天然火山灰使水泥浆体Zeta电位降低,浆体中粒子间静电作用力减弱,粒子更易相互吸附黏聚。而粉煤灰颗粒呈球状且表面光滑,使水泥浆体Zeta电位降低,粒子不易相互吸附黏聚。因此天然火山灰-水泥-粉煤灰复合浆体的屈服应力、塑性黏度和触变性随着天然火山灰掺量增加而增加,随粉煤灰的掺量增加而降低。     

常温下硝酸铵钙对硫铝酸盐水泥的早强作用

研究了常温下硝酸铵钙对硫铝酸盐水泥浆体的流动度、凝结时间、抗压强度、电阻率及浆体内部温度、水化热、水化产物和孔结构的影响,对硝酸铵钙的早强作用机理进行了分析。结果表明,当硝酸铵钙的掺量从0增大到5%时,水泥浆体的初始流动度明显增大,凝结时间显著缩短,6 h,1,3,7和28 d抗压强度均显著提高,电阻率变化速率曲线峰值出现的时间逐渐提前,水泥浆体内部温度逐渐升高,温峰出现时间提前;其掺量在2%以内时,水泥水化放热速率明显加快,1 d累积放热量略有增大,钙矾石的生成速率及生成量均增大,硬化水泥浆体的平均孔径、总孔体积和孔隙率减小。由于硝酸铵钙能够明显加快硫铝酸盐水泥的水化进程,使其早期强度显著提高,因此可用作早强剂。     

煅烧铝土矿尾矿对水泥凝结时间的影响

采用煅烧铝土矿尾矿等质量取代0％、10％、30％、50％、70％的水泥,研究其对水泥标准稠度用水量、凝结时间的影响,结合水化热和X射线衍射(XRD)分析其影响机理,探讨煅烧铝土矿尾矿用作水泥混合材的可行性.结果表明,煅烧铝土矿尾矿作为混合材能增大水泥的标准稠度用水量,缩短水泥的凝结时间,加快水泥早期水化放热速率;掺入50％煅烧尾矿的复合水泥浆体仍然满足通用硅酸盐水泥对凝结时间的要求.     

富镁矿渣对油井水泥浆体膨胀性能的影响及水化机理

80℃水浴养护环境下,研究了不同掺量富镁矿渣对G级油井水泥浆体膨胀性能及其他基本性能的影响,考察了40%富镁矿渣掺量下水泥浆体的工程性能,同时研究了富镁矿渣的水化机理。实验结果表明,掺加富镁矿渣的水泥浆体具有微膨胀性能,其中掺40%富镁矿渣的水泥浆1d线膨胀率为0.0035%,28d线膨胀率为0.0255%;富镁矿渣掺量对水泥浆体凝结时间、流动度、密度影响不大;水化放热量和水泥石早期强度(3d前)均随富镁矿渣掺量的增加而降低,而后期强度(28d后)逐渐升高并高于净浆水泥石;硬化体中Ca(OH)2含量随富镁矿渣掺量增加和养护龄期的延长而降低;40%富镁矿渣掺量下,浆体各项工程性能基本满足固井施工基本技术要求。     

常温可逆温致变色水泥的制备及其智能调温效果研究

采用在白水泥中掺加常温可逆温致变色微胶囊制备出了常温可逆温致变色水泥基材料.掺10%变色微胶囊后,水泥基材料的颜色可在低温时红、蓝、绿色和高温时的白色之间可逆变化,其变色温度在42～58℃;掺加变色颜料微胶囊后,水泥细度有所下降,标准稠度用水量有所增加,凝结时间、安定性均合格,同流动度条件下,硬化水泥浆体抗折、抗压强度出现一定幅度的下降.所研究出的材料具有低温下吸收太阳能、高温下反射太阳能、且能随温度进行可逆转换的智能调温功能,符合建筑物冬暖夏凉的智能调温要求.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.