A Procedure to Measure the Diffusion Coefficient of Water in Brick as a Function of the Water Concentration

A procedure to measure the diffusion coefficient of water in brick as a function of the water concentration has been proposed, based on a method of measuring the mass of a drying brick at both outer ends. In this method, the brick is subjected to one-dimensional drying. The procedure was tested using a simulation with realistic parameter values and experimental inaccuracies. An experiment consisted of 120 s of drying and measuring the masses every 10 s with an accuracy of 10^?6 kg. The sample was first dried to a lower water content and the drying was stopped for some time to allow the concentration profile to approximate a known equilibrium concentration profile, after which another measurement was performed at that lower water content. Minimizing the differences between the masses, as measured and as it follows from the model, gave the value of the diffusion coefficient. The method failed for low water concentrations.     

Estimation of service life of coated brickwork mortar joint

This work reports an investigation into the permeation of chloride in brick masonry mortar joints in three different media (water from rain, runoff, and sea). The coated and uncoated (control) masonry prisms were subjected to 3% chloride solutions for periods of 1-5 weeks each, and the chloride concentration at depth of 20 mm was determined (ranging from 0.012 to 0.327 for immersion days of 7 to 35, respectively, for coated and uncoated prisms of 0.03 to 0.887, respectively). The results show that the service life of the coated brick mortar joint has been increased by 36 years for the sea water sample.     

基于砖含量的再生砖混粗骨料分类研究

针对目前我国再生骨料分类标准适用范围窄,难以指导高砖含量再生骨料综合利用的问题,探究了砖含量对再生砖混骨料吸水率、表观密度和压碎指标等方面的影响规律,并结合现有文献资料统计分析,建立了砖含量与吸水率和压碎指标之间的一般线性关系公式。提出将砖含量作为主要分类控制指标,表观密度、吸水率和压碎指标作为技术控制指标的砖混骨料分级分类新方法。这种方法能够有效完善现有技术标准,使之与再生砖混骨料性质相适应,更加有效地指导砖混骨料在混凝土工程中的资源化利用。     

砖坯干燥过程非稳态二维数值模拟

通过对砖坯干燥传热传质过程的分析，建立了砖坯干燥的准稳态二维数学模型.在此基础上通过数值计算，得到了砖坯温度上升和水分蒸发的曲线.在不同的瓷砖生产厂家实际所测量的数据验证了这一数学模型的有效性.对比了不同位置的温度上升和蒸发速率变化，并简要分析了影响干燥时间的主要因素.     

伟晶石高性能陶瓷透水砖的研制

陶瓷透水砖是一种经过特殊工艺制成的具有连续孔隙的生态型环保陶瓷砖。采用伟晶石为主要原料,先将伟晶石烧制成高强轻质的陶粒,然后将高强陶粒二次烧结成陶瓷透水砖,所制成的陶瓷透水砖的抗压强度和透水性远高于JC/T945-2005《透水砖》标准要求。     

锰渣与再生砖骨料制备免烧砖的性能及应用

锰渣与再生砖骨料均属于大宗固废,提升大宗固废利用率具有重要的环境效益和经济效益。本文利用锰渣、再生砖骨料等制备了免烧砖,探究了锰渣掺量对免烧砖各项性能的影响,且对其微观结构及有害物质浸出行为进行了分析。结果表明:制备的免烧砖外观质量优良,色泽均一,尺寸标准;结合强度要求和抗冻性要求,锰渣掺量不超过10%(质量分数)时,可制备出强度、耐水性和耐久性优异的MU20免烧砖,锰渣掺量不超过15%时,可制备出性能优异的MU15免烧砖;掺适量锰渣的免烧砖中形成了较多的钙矾石相,有利于强度发展。锰渣和再生砖骨料制备的免烧砖可以应用于人行道等市政工程,应用效果良好。研究结果可为锰渣低碳资源化利用以及生态砖制品的生产和应用提供技术支持。     

玻璃熔窑池壁砖内贴水包冷却的开发研究

研究了玻璃熔窑上层池壁砖砖内贴水包的可行性。结果表明,该项技术的使用可以延长池壁砖的使用寿命,增加炉龄,减轻工人的劳动强度,降低生产成本。填补了国内池壁砖冷却的空白。     

花岗岩废料再生混凝土路面砖抗冻融性能研究

采用慢冻法对花岗岩废料再生混凝土路面砖进行50次冻融循环试验,以质量损失与抗压强度作为依据研究影响再生混凝土路面砖抗冻融性变化规律。基于体积膨胀及渗透压理论并结合扫描电镜分析,对比冻融前后再生混凝土路面砖显微结构与水化产物组成,从细微裂缝积累与膨胀性应力作用角度揭示其冻融损伤机理,建立浆体孔隙结构变化模型和浆体浓度差所产生的渗透压模型。研究结果表明,微、细、粗集料分别以20%、30%、50%(质量分数)为最佳取代率的再生混凝土路面砖的质量损失率为1.5%,抗压强度损失率为10.0%,较基准组有所降低,但较大程度上提高了花岗石废料的利用率,且满足试验标准和路用性能的基本要求。微观分析结果表明,浆体水化产物中较高的钙矾石含量使混凝土微裂缝富集,最终形成宏观裂缝导致冻胀破坏,所建立的模型揭示了外界水的侵入引起体积膨胀、毛细孔与凝胶孔中浆体浓度差所产生渗透压引起的膨胀性应力是致使冻融损伤发生的真正原因。     

Diffusion of Large Nitrogen Bubbles into Tap Water Studied by the Rotary Chamber Technique

The rotary chamber technique allows extended observation times of rising bubbles up into the 10‐mm range. After establishing the technique in combination with optical sizing in previous publications, this work completes the case of nitrogen bubbles in tap water. The rise velocity and the mass transfer are measured for five degrees of water saturation. A one‐parameter model equation involving the Archimedes number is offered for calculation. The limit of the analytical boundary layer model is depicted.     

Effect of crack opening on the local diffusion of chloride in inert materials

The paper addresses the problem of the effect of crack opening on the ability of chloride ions to diffuse along a crack. Experimental tests are carried out on an inert material (brick) to prevent crack self-healing. A mechanical expansive core is used to generate cracks of constant width across the thickness of the sample. Five cracked specimens with crack openings ranging from 21 to 128 μm were exposed to a chloride solution for 10 h and then removed to determine the total chloride concentration perpendicular to the crack path. The results show that crack opening significantly influences the ability of chloride ions to diffuse along a crack. Indeed, the chloride profiles indicate impediment of chloride-diffusion capacity in cracks less than 53 μm in width. It was found that this crack-opening threshold agrees with the critical crack opening measured in a uniaxial tensile test that characterizes the interaction phenomena between the fracture surfaces.     

优质水煤浆的研发与燃烧设备的技术改造

渗花抛光砖粉料、微粉抛光砖的面料生产一般使用重油或是煤气。成本比较高，笔者通过对水煤浆的理化性能作为研发重点。使之适合作为渗花抛光砖粉料、微粉抛光砖的面料的燃料。从而代替重油或煤气。降低生产成本。为了做到清洁生产．优化了水煤浆的配方．使用合适的添加剂，使用全酚水制浆．并按一定的比例添加煤气站的副产品——煤粉．从而降低生产成本．并对水煤浆的燃烧设备进行了技术改造．改善了除尘器除尘效果不佳的状况．取得了很好的效果。     

Olive oil mill waste water as a replacement for fresh water in the manufacture of fired clay bricks

This paper describes the introduction of olive mill wastewater (OMW) to replace fresh water normally used in clay brick manufacture. OMW is recognised as the major agro‐food industry pollutant in the Mediterranean/North African olive‐growing region. The research involved adding OMW to laboratory‐produced clay bricks following the same making procedure used at a collaborating Tunisian brick factory. The samples containing OMW were found to be comparable in forming/extrusion performance to a control product that used fresh water. If introduced at the factory scale, this innovation would allow a substantial volume of OMW to be recycled, saving on the fresh water currently used in the brick‐forming process. During the subsequent brick drying operation, most of the OMW (～98% water) would be released as vapour. Once in the kiln, the remaining solids in the bricks (calorific value 21–23 MJ kg^?1) would liberate additional heat, reducing the gross energy from fossil fuel currently required during firing. Copyright © 2006 Society of Chemical Industry     

Characterization and modeling of diffusion process for mass transport through the Tournemire argillites (Aveyron, France)

Argillites are one of the geological formations studied by IRSN for their confining properties for isolation of radioactive wastes. One of the main objectives is the study of water transport through rocks with very low water content and very low hydraulic conductivity by modeling of natural tracer profiles. This paper presents the protocol developed for and applied to the acquisition of data for chloride content in interstitial water of the Toarcian argillites at the Tournemire site (Southern France). This protocol is based on laboratory diffusion experiments and on modeling. Experimental data obtained during the transient and steady-state parts of diffusion experiments enable, respectively, the assessment of the diffusion coefficient and the determination of Cl concentration in pore water. Using this protocol, profiles with depth for both of these data sets have been acquired along the geological sequence. Taking into account the present knowledge of the geological and hydrogeological history of the Tournemire massif, a conceptual model granting the main role for mass transport to diffusion has been proposed. According to this conceptual model, a one-dimensional numerical model was built for simulating the mass transport of chloride through the sedimentary column, over 53 Ma. The good agreement between experimental data and calculated values for both diffusion coefficients and concentrations of chloride confirms that diffusion is likely the main process for mass transport in the massif. This model was also tested with the deuterium content of interstitial water, applying variable concentrations at the aquifer system boundaries for reflecting the thermal dependency of isotopic composition in precipitation. These simulations also reveal the likely important role of heterogeneities, such as fractures, in the variability of tracer concentrations with regards to a simple diffusion profile.     

粉煤灰陶瓷墙地砖的制备工艺及性能研究

以固体废弃物粉煤灰与K2CO3为主要原料,通过预烧处理得到活化的粉煤灰原料,分别在850 ℃、875 ℃、900℃、925℃、950℃度进行常压烧结,制备得到粉煤灰陶瓷墙地砖材料.利用XRD、SEM分别对其物相组成与微观结构进行测试,结合烧成样品的吸水率、体积密度、显微硬度随温度的变化规律,分析了烧结工艺对粉煤灰陶瓷墙地砖性能的影响.研究结果表明:随着烧结温度的升高,样品中液相含量明显增加,在液相流动的作用下,坯体内部的气孔逐渐被填充,固相颗粒被粘结在一起形成连续的整体,从而形成致密的瓷体结构,当烧结温度为925 ℃时,样品的吸水率达到最小值:0.07%,维氏硬度达到最大值:5.9 GPa.而保温时间的增加,液相流动与物质迁移更充分,导致KAlSiO4晶粒尺寸增加,轮廓清晰,但并未对物相及其力学性能产生明显影响.     

利用黄金尾矿制备陶瓷清水砖的研究

为了实现黄金尾矿高效资源化利用,以黄金尾矿为主要原料,采用无压烧结制备了陶瓷清水砖样品,研究了黄金尾矿添加量对样品相组成、显微结构及性能的影响。结果表明,当烧成温度为1 100 ℃,黄金尾矿添加量为70%(质量分数)时,样品性能最优,其抗折强度达73.42 MPa,吸水率为0.10%,气孔率为0.25%,体积密度为2.46 g/cm³,烧成收缩为8.64%,达到GB/T 4100—2015《陶瓷砖》中瓷质砖的要求。样品的相组成为钙长石、石英、白榴子石和赤铁矿。清水砖坯釉结合性好,釉面光滑,色泽均匀。     

A Gravitational Procedure to Measure the Diffusion Coefficient of Water in Porous Materials: A Case Study on Concrete

A new procedure is presented with which the diffusion coefficient of water in partially saturated porous materials can be measured. The first step in the procedure is the creation of a non-equilibrium situation inside a sample by placing it into a centrifuge. In the second step, the mass of the sample is measured by hanging it from two cables, each connected to a balance. The comparison of the time evolutions of the measured masses and the masses as predicted using Fick's second law gives the diffusion coefficient.     

利用提钒尾渣制备烧结广场砖实验研究

以提钒尾渣为主要原料,采用半干法成型方法制备烧结广场砖,通过添加广西白泥、硅铁灰、粉煤灰和A12O3粉可以优化提钒尾渣烧结广场砖的物理指标,提高烧结广场砖的性能.通过条件试验较系统研究了广西白泥配入量、粉煤灰、硅铁灰和A12O3粉配入量对烧结广场砖常温耐压强度和吸水率的影响.条件试验表明:广西白泥配入量为20%左右较适宜、硅铁灰配入量控制在5%以内较适宜、粉煤灰配入量控制在6%以内较适宜、Al2O3粉添加量控制在8%以内较适宜.制得提钒尾渣广场砖的常温耐压强度达到28 MPa以上,吸水率可以降低到10%左右.     

Performance Optimization of a Brick Dryer Using Porous Simulation Approach

In the present study, an innovative method for an accurate simulation and design of a chamber dryer used in the brick/ceramic industry has been proposed. A thorough investigation of currently used dryers is conducted and optimization criteria are detected and discussed. Three-dimensional modeling of the chamber dryer has been performed. In the second step, from the result of 3D modeling, the critical values for heat transfer coefficient are obtained. The governing equations for a two-dimensional brick as a porous solid are derived by combining conservation laws and Fourier's law for heat conduction and Darcy's and Fick's laws for mass diffusion in porous material. The set of partial differential equations governing heat and mass transport in a single brick together with the respective temperature and humidity boundary conditions have been solved numerically based on finite difference method. Finally, an efficient scheme for the air circulation devices, inlet air temperature and humidity, burner characteristics, flow rates, and drying process control have been proposed for a typical industrial-scale brick dryer.     

AN X-RAY STUDY OF THE TOUGHNESS OF PAVING BRICK*

X-ray diffraction photographs of paving brick were compared with those of pure materials. The most important result obtained in this work is the discovery of a line in the X-ray diffraction pattern of paving brick which is characteristic of high-grade shale paving brick. This line, produced by an undetermined crystal, is more intense in the tougher than in the weaker brick. The line falls at 2.03 ± 0.01 Ångström units. A further result of this investigation is the proof that cristobalite, mullite, sillimanite, alumina, and cyanite are not present in the paving brick studied. This also shows that mullite is not produced in ceramic materials at the relatively low temperature at which paving brick are fired.     

Comparison of oxidation behaviors of novel carbon composite brick with traditional carbon brick

Oxidation of carbon is one of the main problems in alumina–carbon based refractory. In this paper, the oxidation behaviors of novel carbon composite brick and traditional carbon brick were investigated by non-isothermal and isothermal experiments, and the samples after oxidation were examined by SEM and EDS analysis. The results show that the oxidation resistance of carbon composite brick is better than that of carbon brick. At 800−1200 °C, the oxidation kinetics of carbon brick follows the linear rate law, which belongs to non-protective oxidation, and the oxidation activation is 5586.76 J/mol. However, the oxidation kinetics of carbon composite brick follows the parabolic rate law, which belongs to protective oxidation. The compressive strength decreases with the increasing mass loss after oxidation due to the carbon loss, so for carbon composite brick which has less content of carbon the oxidation resistance is better than that of carbon brick. Furthermore, the existence of SiC in the surface of carbon composite brick is another reason for its good oxidation resistance.