Fabrication of Baking-Free Bricks Using Gold Tailings and Cemented Materials with Low Alkalinity

The purpose of this paper was using gold mine tailings and cemented materials with low alkalinity to fabricate baking-free bricks.The obtained baking-free brick samples were evaluated by unconfined compressive strength(UCS),water absorption percentage,freezing-thawing cycle,and drying-wetting cycle.The microstructures of the baking-free brick samples were analyzed using X-ray diffraction(XRD)and scanning electron microscope(SEM)techniques.The baking-free brick specimens cured for 28 days with the addition of 10%mixing water consumption and 1:6 cement/tailing ratio tended to obtain favorable comprehensive properties such as a high compressive strength of 15.15 MPa,a low water absorption percentage of 11.8%,excellent freezing-thawing resistance with a 8.9%UCS loss rate after 15 freezing-thawing cycles and good drying-wetting resistance with a 11%UCS loss rate after 10 drying-wetting cycles.The XRD and SEM test results verified that different kinds of hydrate products including C-S-H and C-S-A-H gels,and ettringite were produced during hydration process,which were responsible for good physical,mechanical properties,and durability of the obtained baking-free bricks.Therefore,the experimental results showed that it was practical and reasonable to utilize the homemade cementitious materials in our laboratory to stabilize the gold tailings for production of baking-free bricks,which still met the requirements of major regional construction standards in some countries.

Study on Mechanical Properties and Action Mechanism of Leather Industrial Sludge Aggregate Baking-Free Bricks

Taking an industrial sludge and its preparation of sludge wrap shell aggregates(WSAs)instead of sand to prepare baking-free brick as the research object,the development law of mechanical properties and the influence mechanism of macro and micro characteristic parameters of the bricks under different sludge and WSAs replacement rates were studied through the macroscopic mechanical properties test,with the help of nuclear magnetic resonance(NMR),transmission electron microscopy-energy spectrum and other testing technology and pores and cracks analysis system(PCAS)software.The results showed that the compressive strength of each sample decreased with the increase of sludge content.When the sludge content was less than 30%,it was mainly affected by the water-binder ratio.When the sludge content was more than 30%,it was mainly affected by the sludge content.At the age of 7 days,with the increase in replacement rate of WSAs,the compressive strength of the S10 and S30 groups was higher than that of the control group.The compressive strength of the S50 experimental group was 30.38 MPa,and the loss of compressive strength was slight compared with the control group.The water absorption rate of the 28 days S100 experimental group increased by 10.71%compared with the control group.When the content of WSAs was less than 50%,the holes above 0.1μm in the brick can be reduced and transformed into smaller holes,with a decreasing trend of the plane porosity of the brick.The microscopic results of the baking-free brick showed that the three-phase system of WSAs-interface transition area-mortar was poorly bonded and delaminated compared with the gravel aggregate-interface transition area-mortar system,and damage was more likely to occur in the WSAs and interface transition area.The above results show that it is feasible to use sludge and WSAs instead of sand for the preparation of baking-free bricks.This technology not only solves the problem of sludge disposal,but also protects the over-exploitation of mineral resources,and the technology has a broad application prospect and market value.

Pore Structure Characteristics of Baking-Free Slag-Sludge Bricks and Its Correlations to Mechanical Properties

In order to explore the relationship between the macroscopic properties and pore structure characteristics of baking-free slag-sludge bricks,the compressive strength and water absorption rate using aluminum industrial slag and sludge of different substitution rates were tested.Optical instruments and image analysis software were used to measure the parameters of the pore structure.Specifically,a fractal model was built based on the fractal theory,in which the fractal dimension was used as the characteristic index of the pore structure to analyze the correlation and interaction mechanism between the fractal dimension and the macroscopic mechanical properties.Based on this study,conclusions were drawn as follows:(1)The plane pore structure of baking-free bricks shows good fractal characteristics.With the increase of the aluminum industrial slag content,the fractal dimension becomes smaller and the pore structure develops well;with the increase of the sludge content,the fractal dimension becomes larger and the pore structure becomes worse;(2)As the fractal dimension of the plane pore structure increases,the compressive strength of baking-free bricks falls,and the porosity and water absorption rise;(3)The optimum content of baking-free slag-sludge bricks is aluminum industrial slag 30%and sludge 10%.After 7 days of curing,baking-free bricks boast higher performance,and fully meet the performance requirements of solid concrete bricks(MU40),which can reduce time costs,and enhance enterprise revenue.

Investigation of Refractory Bricks and Oxide Materials Heated in Hydrogen Reduction Conditions

This study aims to provide the basic knowledge for furnace refractory design by investigating refractory property changes occurred in a hydrogen atmosphere.Since refractory bricks are thermodynamically stable in a hydrogen atmosphere at 1100°C,we tried to find out the minute changes.In this experiment,a refractory brick was prepared by andalusite,mullite chamotte,and clay as raw materials and heated to 1100°C in a 100%hydrogen atmosphere for 72 h.It was found that the strength of the brick was decreased and the color was changed to black by the reduction of impurities.And in addition,this study covered research on the slaking risk of MgO raw materials because the minimum temperature is expected to 400°C in fluidized reduction furnaces unlike shaft furnaces.

Visual Analysis of Domestic and Foreign Building Brick Skin Research Based on Citespace

With the progress of the times and the leap of science and technology,the application of brick materials and the research on the brick skin in modern architectural design have shown a dual-track development trend of returning to tradition and innovation.Based on the core collection database resources of Web of Science and the CiteSpace visual analysis tool,this paper constructed and analyzed the spatio-temporal map of keyword co-occurrence network,cluster structure,mutation phenomenon,time course and regional distribution map of building brick skin research.The study revealed that in recent years,the research on brick materials has spanned the study of single material properties and extensively involved in the broad world of construction,especially in the integration of green energy-saving technology,the innovation of fine construction technology of brick skin,and the frontier exploration of digital technology in brick masonry,which has shown particularly significant research vitality and development potential.

Assessment of Cement-Lime as Stabilizer on Mud Bricks

The aim of this study was to evaluate the compressive strength of clay bricks and their stability to water absorption by inserting stabilizers such as lime and cement of 0%, 4%, 6%, 8%, 10%, 12% to 14%. Spectrometric analysis was used to characterize the various stabilizers and the clay used, and tests of resistance and water absorption were also carried out. The clay was found to be an aluminosilicate (15.55% to 17.17% Al2O3 and 42.12% to 44.15% SiO2). The lime contains 90.84% CaO and the cement has 17.80% SiO2, 3.46% Al2O3, 2.43% Fe2O3 and 58.47% CaO in the combined form of tricalcium silicate, dicalcium silicate, tricalcium aluminate and ferro-tetra calcium aluminate. The results showed that the insertion of locally available stabilizers (lime and cement) improved the strength of the material by almost 80% when the lime was increased from 0% to 14% for 14 days. For compressed cement, a 65% increase in strength was observed under the same conditions. Strength increases with drying time, with a 52% increase in strength at 28 days compared to 14 days. Furthermore, compressed cement bricks have a more compact structure, absorbing very little water (32%). In view of all these results, cement appears to be the best stabilizer, and compression improves compressive strength and reduces water absorption.

PVA纤维增强砖骨料再生混凝土数值模拟及尺寸效应研究

与刚性纤维相比,聚乙烯醇(PVA)纤维具有更细的直径和在混凝土中更加复杂的分布。采用两种建模方法分别建立了PVA纤维增强再生混凝土(FFF-BAC)的细观模型。其中,细观模型1(M1):水泥砂浆基质和PVA纤维结合视为一种特殊的工程水泥基复合材料(S-ECC),并与砖粗骨料(BA)、界面过渡区(ITZ)组合成FFF-BAC。细观模型2(M2):FFF-BAC为水泥砂浆、PVA、BA、ITZ组合成的四相材料。结合文献中S-ECC的试验结果,计算S-ECC的应力-应变关系。分别建立M1、M2,并与FFF-BAC单轴压缩试验结果进行比较,结果表明,M1与测试结果更加一致,各项参数的最大误差为11.0%。基于M1研究了FFF-BAC截面的损伤破坏过程,预测了BA掺量对抗压强度的影响,探究了不同尺寸的FFF-BAC的破坏模式,建立了可预测不同BA掺量的FFF-BAC抗压强度的尺寸效应公式。

清华园出土古墓砖力学性能与微结构的关系

对清华园出土的跨越1600年历史的古墓砖,进行了形貌、力学性能和孔隙率等宏观性能测试,以及化学组成、矿物组成等微观性能测试,全面剖析了不同朝代古墓砖的异同.结果表明:自晋朝至清朝,中国民间制砖工艺和制砖质量无显著变化;中国自秦朝就掌握了红砖和青砖2种制砖工艺;相较于红砖,青砖的体积密度更小,孔隙率更大,强度更高,这是因为烧成过程中,附加的焖烧阶段提升了青砖的烧结程度,产生了更高程度的碳酸钙分解和伊利石结晶水的汽化,促进了钙长石和玻璃相的生成.

黄河泥沙制备高强蒸压砖及其性能研究

水少沙多、水沙关系不协调是黄河复杂难治的症结所在。为探索泥沙资源利用新模式,以黄河泥沙为主要原料制备高强蒸压砖样品并测试其性能,采用XRD、SEM等手段分析蒸压砖物相及微观形貌,研究蒸压工艺、原料与掺和料配比对蒸压砖性能的影响。结果表明:随着蒸压温度升高、蒸压时间增加,不同配比的蒸压砖抗压强度均逐渐提高;黄河泥沙、生石灰、矿渣掺量分别为54%、16%、20%,蒸压温度为180℃,蒸压时间为8 h时,制备的蒸压砖抗压强度高达38.76 MPa;掺合料对蒸压砖性能影响的大小排序为矿渣>生石灰>粉煤灰;C-S-H、硬硅钙石、托勃莫来石等水化产物是赋予蒸压砖强度的主要物质。所制备的高强蒸压砖适用于各类民用、公用建筑物的内外墙及房屋的基础建设。

污泥免烧砖的制备及闷料效应的试验研究

本试验以建筑垃圾、水泥、含水率54%的污泥及减水剂作为主要原材料制备免烧砖。通过探究养护时间、污泥掺量、污泥与减水剂闷料时间对免烧砖性能的作用,探讨了影响污泥免烧砖强度的微观机理。结果表明,当污泥免烧砖的配合比设定为25%水泥、40%污泥、35%建筑垃圾,且污泥与减水剂闷料1 h,在标准养护箱里养护28 d后抗压强度提升到13.4 MPa,吸水率降低为18%,软化系数提高为0.90,20次冻融循环后的强度损失率和质量损失率分别降低到1%和0.8%。X射线衍射(XRD)微观试验表明,水化产物钙矾石的衍射峰较高,其含量最大,衍射峰值最大可达7016.7 s^(-1),促进了污泥免烧砖的水泥水化反应。扫描电镜(SEM)微观试验结果显示,此时试样的致密度达到最佳状态,表观密度也最大。

Bricks and Clicks模式下供应链协调研究

建立了由一个制造商和一个分销商组成的基于电子市场的二级供应链模型,讨论了分销商采用Bricks and Clicks模式分销产品,并在电子渠道进行季节后销售的情况,分析了供应链的契约协调问题及供应链成员的利润情况.研究发现改进的回购契约可以使Bricks and Clicks分销模式下基于电子市场的二级供应链模型达到协调,使分销商的订货量达到供应链最优,并且使供应链成员的利润达到Pareto改进,达到"双赢".最后,通过算例验证了结论.

透水砖材料的吸水保水性能比较研究

对比分析了仿石、混凝土和陶瓷3种透水砖的吸水和保水性能,使用MLT-300型水分测定仪等科学仪器,详细研究了各种材料在不同阶段的性能。结果显示,陶瓷透水砖的吸水性能优于其他两种,且3种材料都在空气扩散阶段显示出良好的保水稳定性。

Processing Technology and Quality of Low-fluoride Brick tea

In order to promote the quality of brick tea and reduce its fluoride content, the fluoride contents in leaves of 25 tea varieties at the .stage of one bud and five leaves were determined by the method of fluodde-ion selective electrode method. The results showed that the fluodde contents in the 25 varieties were in the range of 181.92-345.06 mg/kg, end the fluoride content in ＇Zhongcha 302＇ was the lowest. Based on traditional production process of brick tea, 3 new low-fluoride brick tea production processes with ＇Zhongcha 302＇ as the raw material at the stage of one bud and five leaves were constructed. The fluoride content, physicochemical in- dex, sensory end main chemical contents in the brick tea samples were determined. The best processing process of Iow-fluodde brick tea was process 3, which included aldng, fixing, rolling, second fixing, second roiling, sun-drying, pile-fermentation, steaming, pile-fermentation, drying and shaping into brick by vapor treating. The re- sults showed that the fluoride content and physicochemical index of the brick tea sample of the third low-fluoride brick tea production process accorded with National Standard GB/T 9833.4-2013. The sensory evaluation of the brick tea sample was better than that of brick tea manufacture by the traditional process. The water extract, tea polyphenols, amino acids, caffeine and water-soluble sugar in the brick tea sample increased by 9.41%, 36.39%, 26.94%, 27.23% and 15.29%, respectively. Low-fluodds bdck tea could be produced by selecting low fluoride tea varieties, controlling the tondemess of fresh leaves, and optimizing the processing technique.

The Effects of Nutrition Lick Brick and Salt Brick as Supplement Feed on the Production Performance of Tan Sheep

In the paper, the effects of nutrition lick brick and salt brick as supple-ment feed on the performance of Tan sheep were studied. 36 fattening Tan sheep with the average weight of about 23 kg were chosen, they were randomly divided into 3 groups according to the weight, and each group had 12 sheep. Control group was fed with normal daily ration, experimental group 1 was fed with normal daily ration＋nutrition lick brick, experimental group 2 was fed with normal daily ration＋salt brick, the experimental period was 60 d. The results showed that 1） compared with CK, daily gain of group 1 improved 17.09%（P〈0.01）, feed conversion ratio reduced 11.69%（P〈0.05）, and average gross profit per sheep improved 51.65 yuan; daily gain of group 2 improved 7.03%（P〈0.05）, feed conversion ratio reduced 4.06%（P〉0.05）, and average gross profit per sheep improved 19.78 yuan; 2） compared with group 2, daily gain of group 1 improved 9.40%（P〈0.05）, feed conversion ratio re-duced 7.96%（P〈0.05）, and average gross profit per sheep improved 31.87 yuan;these indicated that nutrition lick brick and salt brick as supplement feed for Tan sheep both can improve the production performance of Tan sheep, and the supple-mentary feeding effect of nutrition lick brick was better.

用brick-wall方法计算黑洞熵的再讨论

在薄层模型brick wall方法的基础上 ,进一步研究了黑洞熵的计算 ,发现黑洞熵来源于其视界面上每一个面元的贡献 .熵与视界面积成正比 ,不但适用于整个黑洞 ,也适用于黑洞视界的局部 .这一思想不但可以用于计算表面各点温度不同的动态黑洞的熵 ,而且使得人们对黑洞熵与视界面积关系的认识更加深入了一步 .

铁尾矿制备免烧砖的研究

为解决尾矿固废大量堆积问题,以商洛大西沟铁尾矿为主要原料,粉煤灰、石膏为辅助原料,水泥为胶凝剂,采用压制成型法制备免烧砖。研究了水泥用量、粉煤灰用量、拌和水用量和成型压力对样品性能的影响。结果表明,铁尾矿、水泥、粉煤灰、石膏的质量比为57∶14∶23∶6,拌和水用量为10%,成型压力为20 MPa时,经自然养护28 d后,免烧砖样品抗压强度为33.4 MPa,满足JC/T 422—2007中MU25等级要求。

The Cultural Implication of Brick Carving Model Calligraphy in Shanxi Chang's Manor

Focusing on the unique style of brick carving model calligraphy in Shanxi Chang's manor,this research analyses the content and feature of the different parts of brick carving,and discuses the presenting cultural deposits.It reflects the deep Confucian culture of Shanxi Chang's manor,with the peculiar charming in culture and aesthetic value.

隧道弃渣制备免烧透水砖及性能研究

以隧道弃渣作为骨料,水泥为胶结剂,粉煤灰为辅助原料,通过压制成型法制备免烧透水砖,考察了不同因素对样品性能的影响。结果表明,当配合比设计参数为:孔隙率20%,隧道弃渣、水泥和粉煤灰质量比8∶1∶1,水灰比0.3,减水剂用量1%,得到透水砖的最佳工艺条件,即成型压力为2.5 MPa,保压时间为50 s,采用标准养护28 d。此条件下制得的免烧透水砖抗压强度为12.3 MPa,透水系数为3.25×10^(-2) cm/s,本研究为隧道弃渣综合利用提供了新途径。

果树穴贮砖对南疆温室软籽石榴光合特性及氮素吸收的影响

为探究适用于南疆温室沙地土壤条件下的氮肥增效措施,以3 a生‘突尼斯’软籽石榴为试材,设置无果树穴贮砖(CK)、施加果树穴贮砖A(T1)和果树穴贮砖B(T2)共3个处理,研究施加果树穴贮砖对软籽石榴光合特性及氮素吸收的影响。结果表明:T1、T2处理显著增加了1个灌水周期内第1天的石榴叶片叶绿素指数及第3天和第5天的氮平衡指数,提高了叶片净光合速率、气孔导度、胞间二氧化碳浓度、蒸腾速率的日均值,总体上以T1处理较好;与CK相比,T1和T2处理的石榴茎、叶、根中的全氮、硝态氮含量均有显著提升,同时茎和叶中的铵态氮含量也有显著提升,总体表现为T1>T2>CK。综上,施加果树穴贮砖有助于提升南疆温室沙地土壤条件下软籽石榴植株光合性能以及氮素吸收,本研究以施加果树穴贮砖A处理效果最佳。

氨碱白泥制备免烧砖的工艺及性能研究

以氨碱白泥固废基胶凝材料为胶结剂,矿山废石和铁尾矿为砂石骨料压制成型制备免烧砖,对制备免烧砖工艺过程中的砂石质量比、胶凝材料用量、用水量和成型压力进行了系统研究,优选最佳工艺参数进行了免烧砖性能研究,并通过X射线衍射和扫描电镜分析了免烧砖强度形成机理。结果表明,砂石质量比为90∶10,胶凝材料用量为20%,用水量为10%,成型压力为20 MPa,制备出的免烧砖性能最佳,能达到GB/T 21144—2023《混凝土实心砖》中MU35等级要求。氨碱白泥固废基胶凝材料水化形成水化硅酸钙、水化铝酸钙、钙矾石等,将砂石骨料包裹交联成致密的结构,保证免烧砖的强度。利用氨碱白泥生产免烧砖,为氨碱白泥减量化、大宗化利用提供了一种有效方案。