Compressive evaluation of mansory bricks produced with industrial byproduct aggregates

This study evaluates the effect upon the compressive strength of ceramic masonry bricks when industrial byproducts known as soot are added. The research includes an analysis of the granulometric properties of the constituent components, performed manually with ASTM C136-01 screens to determine particle size using apertures sized from large to small; an analysis by XRD of the mineralogical phases present; a compressive strength analysis performed using standard compression testing machinery; and a water absorption measurement calculated according to Colombian Technical Standard: 4017:2015—Methods for the Sampling and Testing of Masonry Elements and other Clay Products. Five trials were performed using different mixtures of clay and soot, at substitution rates of 20%, 30%, 40%, 50%, and 60%. These mixtures were prepared under identical conditions in order to ensure validity of the resulting comparisons. The results showed that bricks with 20%, 30%, 40%, and 50% added soot demonstrated superior structural strength compared to conventional units. Bricks incorporating 60% soot, however, were found to have lower strength and high porosity.     

Analysis of temperature effect on ceramic brick production from alluvial deposits, Tamilnadu, India

This study focuses on the thermal behaviour of alluvial clays in the production of ceramic brick industries, which are largely found on the bank of the Cauvery river, Tamilnadu, India. Clay bars were prepared which consisted of quartz, kaolinite, illite, chlorite, feldspars and iron oxides. The test samples were fired in the range of 700–1100 °C and were examined with chemical analysis, thermogravimetric–differential thermal analysis (TG–DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). An increase in firing temperature resulted in dehydroxylation of clay minerals, persistence of quartz and formation of Ca-anaesthetic plagioclase. SEM images visualized the vitrification of the fired bricks, which increased the compressive strength of the fired bars. The bricks made with alluvial clays displayed less water absorption and higher compressive strength, indicating that they could be used in the brick industry. The results of this work assisted the industries to select more appropriate natural clay composition and firing dynamics for making the bricks.     

Characteristics of heat insulating clay bricks made from zeolite,waste steel slag and expanded perlite

In order to lessen the energy loss of buildings during the operation phase, and also considering the importance of sustainable construction, producing bricks having more desirable thermal characteristics has become essential. In this study, insulation bricks composed of expanded perlite (EP), natural zeolite, ground granulated blast furnace slag (GGBFS) and clay were fabricated. The effect of replacing clay with GGBFS, zeolite and EP in amounts up to 15%, 15%, and 50% respectively on the bricks' properties was investigated. Mix proportion parameters of bricks were analyzed using the Taguchi method. Various properties of bricks including density, weight loss, shrinkage, apparent porosity, water absorption, resistance to freezing and thawing, compressive strength, thermal conductivity, and microstructural analysis of fired bricks were examined and compared against standard requirements for bricks. Overall, the results showed that while satisfying the standard requirements, bricks containing the aforementioned additives had lower thermal conductivity compared to normal bricks, and therefore, they could be utilized as heat insulation materials.     

Effects of expanded vermiculite on the properties of fired bricks from water treatment sludge

In the present study, the suitability of using water treatment sludge (WTS) as the main raw material and expanded vermiculite (EV) as aggregate in the production of fired bricks was investigated. Mixtures containing between 75%–100% WTS by weight (wt.) and 5%–25% EV by wt. were prepared at various proportions. The mixtures were compressed under 40 MPa pressure and fired at 1000°C. It was found the incorporation of EV in fired bricks resulted in a decrease in thermal conductivity, compressive strength, and bulk density and an increase in apparent porosity and water absorption. For the addition of 5%–25% EV by wt., bulk density ranged between 2.01 and 1.69 kg/m³, compressive strength 19.3 and 8.3 MPa, water absorption 21.1% and 10.1%, and thermal conductivity 0.678 and 0.374 W/m-K, respectively. Based on the promising physical and mechanical properties, fired bricks incorporating WTS and EV can potentially offer an alternative to the traditional production of clay bricks while adhering to the principle of a circular economy.     

Combinations of organic and inorganic wastes for brick production

A mixture of different types of clay was blended with rice straw (RS) and microcrystalline cellulose (MCC) in the presence or absence of cement kiln dust (CKD) to produce new types of brick. The ratios of RS and MCC were 0, 5, and 10% w/w in the absence of CKD while they were kept at 5% w/w in its presence. The samples produced were compared to “blended” bricks prepared using 10% w/w CKD. Samples were fired at temperatures up to 1000°C and their surface and composition studied using SEM and XRD. Moreover, the chemical and physical properties of prepared bricks were determined. Introducing RS reduced both strength and bulk density but increased porosity of prepared samples. The presence of MCC alone increased the compressive strength, while combining RS with CKD overcame the decrease in strength resulting from the presence of RS alone. This has enabled the production of light‐weight low‐cost bricks with a compressive strength close to nonblended bricks, especially at high firing temperature. POLYM. COMPOS., 35:174–179, 2014. © 2013 Society of Plastics Engineers     

赤泥烧结砖的泛霜分析

赤泥烧结砖因赤泥使用量大、制砖成本低而成为研究的热点。普通烧结砖大多存在泛霜严重的问题,利用赤泥、页岩、硅矿、河沙和粘土制备烧结砖,研究了赤泥单因素、页岩单因素、硅矿单因素的泛霜现象。结果表明,这些赤泥烧结砖的泛霜都属于中轻程度,其各性能都较好的配方,泛霜属于轻微程度。XRD显示这些赤泥烧结砖的泛霜物质是硫酸钠。     

Utilization of by-products from western coal combustion in the manufacture of mineral wool and other ceramic materials

The ash by-products from combustion or gasification of western U.S. coals have chemical and mineralogical characteristics that lend themselves to utilization in ceramic materials. Laboratory and pilot-scale fabrication of four such materials has been studied. Cyclone slag from four lignite-fired power plants and a dry scrubber ash have been fabricated into mineral wool insulation in a pilot-scale cupola. Extruded and fired mixtures of fly ash, clay and ground glass have produced ceramics with extraordinary high flexural strength. Ceramic glazed wall tile that utilize fly ash in place of clay have been prepared and shown to meet most specifications for fired clay tile. Both fired and unfired dry-pressed brick containing 100% western fly ash have met ASTM specifications for fired clay brick.     

The use of recycled paper processing residues in making porous brick with reduced thermal conductivity

Production of porous and light-weight bricks with reduced thermal conductivity and acceptable compressive strength is accomplished. Paper processing residues were used as an additive to an earthenware brick to produce the pores. SEM-EDS, XRD, XRF and TG-DTA analysis of the paper waste and brick raw material were performed. Mixtures containing brick raw materials and the paper waste were prepared at different proportions (up to 30 wt%). The granulated powder mixtures were compressed in a hydraulic press, and the green bodies were dried before firing at 1100 °C. Dilatometric behaviours, drying and firing shrinkages were investigated as well as the loss on ignition, bulk density, apparent porosity, water absorption and thermal conductivity values of the fired samples. Their mechanical and microstructural properties were also investigated. The results obtained showed that the use of paper processing residues decreased the fired density of the bricks down to 1.28 g/cm³. Compressive strengths of the brick samples produced in this study were higher than that required by the standards. Thermal conductivity of the porous brick produced in this study (<0.4 W/m K) showed more than 50% reduction compared to local brick of the same composition (0.8 W/m K). Conversion of this product to a perforated brick may reduce its thermal conductivity to very low values. Successful preliminary tests were conducted on an industrial scale.     

Leaching and Solubility Analysis of Porcelain-Recycled Tile Residues in Clay Bricks

In this study, a porcelain tile residue was used to produce clay bricks. The residue was characterized (XRF, PSD, dilatometry, solubility, and leaching analyses) and was added to a brick paste, forming compositions that were extruded, dried, and fired at 1000°C. The fired specimens were tested [compressive strength, shrinkage, apparent density, water absorption, phase analysis (XRD), microstructure (SEM), leaching, and solubility]. The results showed that the porcelain residue was a noninert material. When added to the brick paste, the residue shows an improvement of some properties due to its alkaline content acting as a flux in the clay paste and causing the vitrification of the structure.     

Degradation of MgO–C refractories by MnO-rich stainless steel slags

In order to identify the influence of MnO on the wear rate of MgO–C bricks for the production of high Mn stainless steel, MgO–C refractory samples were exposed to slags containing different MnO levels (up to 26 wt.%). Although the investigations of the worn brick microstructures revealed the presence of numerous Mn-rich metal particles and the formation of a (Mg,Mn)O solid solution at the slag/refractory interface, no clear evidence of wear rate enhancement was observed due to high MnO concentration in the slags. With respect to refractory wear, the MgO content in the slag is the dominant factor. The degradation processes are discussed by combining experimental results and thermodynamic calculations.     

Recycling the insoluble residue from titania slag dissolution (tionite) in clay bricks

Tionite is the insoluble residue from the titania slag dissolution process for TiO₂ manufacturing. It is a fine-grained sludge consisting of rutile, anatase, amorphous phase and bassanite. Chemical composition is TiO₂ (ca. 50%), SiO₂ (ca. 30%) and minor Al, Ca, Mg, and Fe, plus residual sulfur, implying an acidic pH of waste. Moisture is about 35% of dry weight. The potential of tionite as colouring agent in clay bricks was appraised by admixing (up to 9%) either as-produced or neutralized tionite to four industrial clay bodies. The effect on technological behaviour was assessed by laboratory simulation of the industrial brickmaking process and determining working moisture, drying sensitivity, shrinkage and bending strength, water absorption, bulk density, efflorescence, and colour. The use of tionite is technologically feasible, with little adjustment of industrial cycle, and resulting brick performances depend remarkably on the composition and properties of clay bodies. Carbonate-rich bodies seem to be affected by tionite more during drying than during firing; carbonate-poor bodies range from little changes to consistent worsening of brick performances. No relevant changes of process and product parameters were found up to 3% tionite. Additions over 5% induce significant variations, such as increase of working moisture and water absorption, decrease of bulk density and bending strength. A definite and consistent improvement of this technological behaviour is achieved by using neutralized tionite. The yearly output of tionite could be entirely recycled by approximately four average-size brickworks adding about 3% of residue (dry weight).     

电镀污泥烧结砖的物理力学性能及浸出风险评估

探讨了在烧结制备红土砖和黏土砖的过程中掺入不超过10%(质量分数)的电镀污泥对其物理力学性能的影响,并评估了其重金属长期浸出风险。结果表明,掺入10%电镀污泥的烧结砖质量损失最大达到11.23%,线性收缩率最大达到-5.7%,吸水率最大达到11.47%,孔隙率最大达到22%,抗压强度最大达到15.66 MPa,皆满足国家相关标准要求;黏土砖的各项性能优于红土砖。浸出风险研究表明,总铜、总锌、总铬、总镍的最大浸出浓度分别为0.45、0.92、0.13和0.19 mg/L,远低于危险废物鉴定标准,表明掺入电镀污泥的烧结砖不是危险废物。     

Use of steel slag and quartz sand-tailing for the preparation of an eco-friendly permeable brick

In order to effectively utilize industrial solid wastes (ISW), an eco-friendly permeable brick was successfully prepared by using quartz sand-tailing and steel slag. The influence of sintering temperature on the properties including permeability, apparent porosity, water absorption, bulk density, mechanical strengths, and chemical stability was systematically investigated. The research results show that with increasing sintering temperature, the structure of the permeable brick gradually become dense, which may be due to liquid phase sintering caused by a small amount of glass-liquid phase (Ca-Fe-Si-Al-O glass system). The permeability, apparent porosity, and water absorption decrease gradually, while the bulk density and mechanical strengths increase monotonously. Furthermore, the best sintering schedule for the permeable brick is 1320°C for 1 hour, with the optimized parameters, the permeable brick exhibits excellent properties (permeability, 3.65 × 10⁻² cm/s; compressive strength, 34.1 MPa; bending strength, 5.2 MPa; chemical stability, above 99%), wherein the permeability is far beyond Chinese standard (1 × 10⁻² cm/s). The permeable brick in this work provides a promising way for the recycle of ISW. Even better, it can maximize the introduction of quartz sand-tailing and steel slag (reach 100%) and create huge economic benefits while protecting environment.     

Fabrication of porous mullite-based ceramic bricks from Al-rich water treatment sludge and kaolinitic-based clay

A large quantity of water treatment sludge (WTS) is generated yearly from Ghana's Weija water treatment plant. The sludge contains some heavy metals and other toxic chemicals, which must be managed to minimize environmental impact. In the current work, WTS was mixed with varying quantities of kaolinitic-based clays (kaolin and lithomargic clays) to produce porous mullite-based bricks. The bricks were fired at 1200°C for 1 h, and their properties were determined. Lithomargic clay-based mixtures had less dimensional variation and were suitable to produce near-net shape bricks compared to WTS-based bricks. The addition of WTS increased the linear firing shrinkage and apparent porosity whilst decreasing bulk density and compressive strength. Porous mullite-based bricks fabricated from lithomargic clay exhibited high compressive strength (6.3 MPa) at 10 wt.% WTS addition. The highest apparent porosity of 27% was attained at 40 wt.% WTS addition with compressive strength of 5.1 MPa and thermal conductivity of .5 W/m K.     

Behavior of magnesia bricks in furnaces for the production of manganese alloys

Conclusions The application of dense magnesia bricks contributes to increased durability of the lining in metal manganese and manganese slag producing furnaces.The life of magnesia brick linings with an 11 to 13% porosity amounts to 45 days.The employment of large-size bricks hightens the resistance of the furnace bottom.Periclase-spinel brick proved unsuitable in the production of manganese slag.It is suggested that bricks with a porosity of 14 to 16% be tested for the purpose of determining optimal porosity.     

Influence of mineralogy and firing temperature on the porosity of bricks

The changes in brick porosity upon firing (700 up to 1100 °C) and its relation to the mineralogical composition are examined. Two types of raw clay with a composition representative of that used in brick-making industry were selected to manufacture the bricks: one contains notable amounts of carbonates, with a grain size of under 1 mm, and the other is predominantly quartzitic and lacking in carbonates. We demonstrate that the presence or absence of carbonates strongly influences the porosity development and, therefore, the brick texture and physical-mechanical properties. The carbonates in the raw clay promote the formation of fissures and of pores under 1 μm in size when the bricks are fired between 800 and 1000 °C. The absence of carbonates results in a continuous reduction in porosity and a significant increase in the pore fraction with a radius (r)>1 μm as the firing temperature rises and smaller pores coalesce. Porosity and pore size distribution results obtained from the combined use of hydric tests (HT), mercury intrusion porosimetry (MIP) and digital image analysis (DIA) of scanning electron microscopy photomicrographs are compared. A clear correlation between the water absorption and drying behaviour of the bricks and the porosity plus pore size distribution is observed. DIA discloses the evolution of size, shape and connectivity of macropores (r> 1 μm) and evidences that MIP results underestimate the macropore content. Conversely, MIP gives a good estimate of the open porosity and of the distribution of pores with r<1 μm. It is concluded that the combined use of these complementary techniques helps to fully characterise the pore system of bricks. These results as well as the study of the evolution of the speed of ultrasound waves vs. time yield useful information to evaluate the bricks physical–mechanical behaviour and durability. The relevance of these findings in the conservation of historic buildings is discussed.     

碱激发-碳养护对铜尾矿固化砖的作用机理研究

以细粒级铜尾矿作为主要原材料,水玻璃为激发剂,辅以少量水泥和粉煤灰,通过碱激发反应、压制成型及碳养护制备铜尾矿固化砖。采用X射线衍射、热重-差示扫描量热法、压汞法和扫描电子显微镜-能谱仪等对试样的物相组成、碳化产物、孔隙分布和微观产物形貌进行分析,探讨碱激发-碳养护对铜尾矿固化砖性能提升的影响规律。结果表明,水玻璃可以激发铜尾矿的部分胶凝活性,生成更多絮凝状C-S-H凝胶,改善铜尾矿固化砖的微观孔结构进而提升其抗压强度。碳养护的时机选择至关重要,固化砖成型后立即进行碳养护,碳化反应会与碱激发反应竞争OH^-,生成文石型和方解石型CaCO₃,导致C-S-H凝胶的生成量减少,孔隙率增大,抗压强度降低。固化砖密封养护84 h后再碳养护84 h,其7 d抗压强度可提高20.9%,碳化产物CaCO₃填充内部孔隙,有害孔和多害孔数量大幅减少,无害孔数量增加,整体结构密实程度提高,从而解决铜尾矿固化砖表面泛霜的问题。     

SOME EXPERIMENTS WITH ZIRCON AND ZIRCONIA REFRACTORIES*

This is a record of the results of five years' research on refractory uses for a chemically purified grade of zircon and electrically fmed zirconia of high purity. The products investigated included semi-permanent foundry molds, refractory brick and cements, ladle nozzles, and crucibles. Electric firing and a small oil-fired tunnel kiln are described. Sintered zircon grog was found superior to electrically fused grog. Zircon brick made with 50% grog, using 20% milled zircon for the permanent bond and fired at 1600°C for an hour, showed no firing shrinkage, very slight volume change, and high compressive strength at 1600°C. They were extremely resistant to spalling but did not resist basic slags or metallic oxides very well a t high temperature. Zircon-bonded magnesite brick were more refractory than ordinary magnesite, more resistant to spalling, and had about the same slag resistance magnesite. Zirconia was more refractory than zircon and had better slag resistance. Lime-bonded zirconia crucibles of good spalling resistance were made, but the cost was higher than that of zircon. The effects of various binders are discussed.     

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。     

Physico-chemical characterisation of bricks all through the manufacture process in relation to efflorescence salts

Due to the high competitiveness of the ceramic product market, quality and technical requirement are increasing. The efflorescence problem is a phenomenon that affects the aesthetic quality of brick facades and which is not easily dealt with. The aims of this work are to study the key physical and chemical parameters for this phenomenon in all activities of the brick manufacturing process and to evaluate the influence of the additives employed on the appearance of the efflorescence phenomenon. Porosity and specific surface, mineralogical analysis, total chemical content and soluble salts were determined on green, dried and fired brick, both when no additives were added to the manufacturing process and also when ammonium lignosulphonate and barium carbonate were used as additives. The main mineralogical phases and water soluble salts in the efflorescence phenomenon have been obtained. In some cases, relationships between soluble salts in the end product and soluble salts in the efflorescence have been established. From the obtained results, the use of a mixture of ammonium lignosulphonate and barium carbonate together with the control of the firing process variable is recommended in order to prevent this phenomenon.