Study on fired bricks with replacing clay by fly ash in high volume ratio

In present paper fly ash in wet state with low quality was used as raw material to replace clay to make fired bricks. The effect of fly ash with high replacing ratio of clay on firing parameters and properties of bricks were studied. The results indicate that the plasticity index of mixture of fly ash and clay decrease dramatically with increasing of replacing ratio of fly ash. Additive A can be chosen to improve the plasticity index of mixture to meet plastic extrusion used in most brick making factories. The sintering temperature of bricks with high replacing ratio of fly ash was about 1050 °C, which is 50–100 °C higher than that of clay bricks. The properties of fired bricks were improved by using pulverized fly ash. The fired bricks with high volume ratio of fly ash were of high compressive strength, low water absorption, no cracking due to lime, no frost and high resistance to frost-melting.     

城市给水厂污泥建材资源化利用试验研究

以给水厂污泥、基坑外运土、炉渣为原料,经过混合搅拌、挤出成型、干燥、焙烧等工序,试验烧制成小型空心砖。对成品试样进行抗压强度、石灰爆裂、泛霜、热工性能、放射性等方面的性能测试,各项检测结果均符合国家标准规定要求,由此表明城市给水厂污泥生产烧结空心砖是可行的。     

粘土掺量对赤泥烧结砖性能的影响

利用赤泥制备了抗压强度达到国家烧结砖标准中MU30级要求的烧结砖,并研究了粘土掺量对赤泥烧结砖性能的影响。研究表明粘土的掺入能改善坯料的可塑性,增大烧结砖的收缩,扩大烧结砖的烧结温度范围,提高烧结砖的抗压强度。     

Effect of grog addition on the properties and microstructure of a red ceramic body for brick production

In the present paper crushed fired brick waste, known as grog, was used in mixtures with clayey body to make typical red ceramics for bricks. The effect of the grog addition up to 20 wt% on the extrusion stage as well as on properties and microstructure of bricks fired at 700 °C was evaluated. The results indicate that the extrusion of the unfired clayey body was not impaired by the grog addition. Additions above 5 wt% decreased the mechanical strength of both the dry body and the fired ceramic pieces. This is associated with the increase in porosity during the firing stage due to the grog behavior.     

Weathering traces in ancient bricks from historic buildings

The aim of this work was to determine the type of weathering suffered by bricks belonging to a number of historic buildings in Toledo, Spain. These bricks had been exposed to either aerial or burial environments, came from different places in the selected buildings, were of different mineralogical composition, and had been fired at different temperatures. X-ray diffraction, scanning electron microscopy and the analysis of their physical properties showed the best conserved to be those that had been buried. Buried Roman bricks made from non-calcareous materials fired at >900 °C and with a vitrified matrix showed few signs of weathering. Buried Islamic and Mudejar-Romanesque bricks made from calcareous clays and fired at temperatures of <800 °C were similarly well conserved. These showed calcareous cementation of their pore systems, which improved their physical properties. Bricks from the external and internal walls of buildings (e.g., Islamic–Mudejar and Romanesque bricks from inner courtyards and cellars) that had been exposed to aerial conditions were less well conserved. These were made from calcareous materials and had been fired at high temperatures (>900 °C). They showed a number of weathering traces but overall were still in relatively good condition. The worst conserved of all were neoclassical bricks from upper storey internal walls. These were made of calcareous material and had been fired at temperatures of between 800 and 900 °C.The mineralogical composition of the raw materials, the firing temperature, the location of the bricks in the buildings, the environments to which they had been exposed, the action of natural or polluted filtration water, the action of microorganisms and the reigning environmental conditions, all contributed towards the state of conservation of the bricks. Such knowledge may help in the choice of appropriate cleaning or restoration treatments for architectural heritage of brick construction.     

Glazed tiles produced using paper sludge,glass cullet and a natural red clay: an experimental study

The paper describes the production, in single fast firing, of tiles containing 30 wt% of a natural red clay and a mixture of 42 wt% of paper mill sludge and 28 wt% of glass cullet which were coated with a commercial ‘matt white’ glaze. Fired materials have been characterized as a function of the top temperature (1090 or 1140 °C) reached at the top of the fast sintering process made by an industrial roller kiln. It has been observed that tiles fired at 1090 °C display the best overall performances because the matt glaze well covers the substrate, thus ensuring that the mechanical and physical properties of the tiles conform to the official standard.     

Assesment of clay bricks compressive strength using quantitative values of colour components

This study was conducted to assess the relationships among firing temperature, colour components and compressive strength of bricks. Lightness (L*) and chromaticity (a* and b*) of 10 replicated brick samples fired at temperatures 700–1050 °C in steps of 25 °C under free access of air, were measured with a colorimeter, which uses an L* a* b* colour space. Increasing firing temperature significantly increased the compressive strength of bricks. The values of L* slightly increased with firing temperature up to around 800 °C then decreased as temperature increased further. The values of b* and a* increased with increasing firing temperature up to around 900 °C then rapidly decreased with further increases in firing temperature. A negative relationship occurred between each of L*, a*, and b* and compressive strength. Compressive strength was adequately described by colour components of L* and b* by linear regression equations (R² = 0.87 for L*, and R² = 77 for b*). However, the relationship occurred between a* and compressive strength was quite poor. It was concluded that the numerical values of colour components of L* and b* may be used to predict and judge the compressive strength of bricks. However, the method can not be generalized before its calibrated with different raw materials under different firing conditions.     

烧结制度对膨润土页岩烧结砖性能的影响

将页岩与膨润土以不同比例混合,通过抗压强度、烧结收缩率、体积密度、吸水率和显气孔率作为指标,分析了不同的烧结温度及烧结时间对膨润土页岩烧结砖性能的影响。     

A phoenix from the flames

In this detailed account of an unusual project in Pondicherry, India, the celebrated Dutch ceramic artist and sculptor describes the building of a small, vaulted brick house. The house, however, was built with ‘green’ bricks; it was used as a kiln for the firing of a pile of other green bricks and tiles so that, after firing, the house itself would be transformed into a structure of hardened fired‐clay bricks. The experiment took place at the Golden Bridge Pottery, established by American potters Ray Meeker and Deborah Smith some sixteen years ago. The author's consultancy role in the project was grant‐aided by the Dutch government.     

Preparation of eco-friendly construction bricks from hematite tailings

With the objective of reducing the negative impacts on environment and utilizing the secondary resource of tailings, the possibility of making construction bricks by using the hematite tailings from western Hubei province of China was investigated. Besides hematite tailings, the additives of clay and fly ash were added to the raw materials to improve the brick quality. Through the process of mixing, forming, drying and firing, the bricks were produced. The optimum conditions were found to be that the hematite tailings content were as high as 84%, forming water content and forming pressure were respectively in the range of 12.5–15% and 20–25 MPa, and the suitable firing temperature was ranged from 980 to 1030 °C for 2 h. Under these conditions, the mechanical strength and water absorption of the reddish fired specimens were 20.03–22.92 MPa and 16.54–17.93%, respectively, and the other physical properties and durability were well conformed to Chinese Fired Common Bricks Standard (GB/T5101-2003). The phases and morphologies of the green tailings and fired specimen were characterized by XRD and SEM. The results showed that the main mineral phases of the product were hematite, quartz, anorthite and tridymite, which were principally responsible for the mechanical strength of bricks.     

Using phosphogypsume and boron concentrator wastes in light brick production

In this study, use of wastes produced in phosphoric acid plants and boron concentrators in producing structural brick has been investigated. There are several parameters involved in using these wastes in brick production namely the rate of added waste, firing speed and firing temperature. The performance of these parameters can be measured by several criteria such as natural drying shortening, water absorption and weight loss. Therefore, so many experiments are needed to investigate the effects of these parameters on the bricks produced with these wastes. To this end, around 220 experiments for three different material combinations namely original waste plus normal brick clay, washed waste plus normal brick clay and normal brick clay with no additive were carried out. The results have shown that the industrial wastes produced by phosphoric acid plants can improve the performance of the bricks in terms of drying shortening, weight loss and water absorption.     

Preparation of load-bearing building materials from autoclaved phosphogypsum

Previous studies have been carried out on calcined phosphogypsum (PG) for making the building materials. The present study was focused on autoclaved PG and its use in making load-bearing wall bricks. Autoclaved PG was prepared from original waste PG with steam pre-treatment. The crystalline phase, morphology, and thermal characteristics of original waste PG and autoclaved PG were investigated by XRD, SEM, and SDT. Then bricks of the size of Chinese standard brick were prepared from different types of PG in the PG-fly ash–lime–sand system. Results showed that the compressive strength of bricks from autoclaved PG by lower-pressure steam of 0.12 MPa, 120 °C for 16 h was much higher. The flexural strength and compressive strength of the bricks could reach 4.0 MPa and 15.0 MPa, respectively. The durability of the bricks was investigated by 15 freezing–thawing cycles at temperatures from ?20 °C to 20 °C, and the weight loss was only 0.029% after all of cycles. Hemihydrates (CaSO₄ · 0.5H₂O) were dehydrated products from dihydrates in original PG with lower-pressure steam treatment, and hemihydrates were susceptible to absorbing the humidity and were transformed into densified re-crystallization gypsum (CaSO₄ · 2H₂O) that contributed to the final strength of bricks. Microstructural characteristics of bricks were investigated by XRD and SEM. Tobermorite was the significant hydrated product, which contributed to the strength of bricks. The use of autoclaved PG for making load-bearing wall bricks was recommended instead of conventional burnt clay bricks.     

Reuse of waste bricks in the production line

The main objective of this research was to investigate the addition of waste-brick material in brick production. The effects of recycling of waste brick material on the durability and mechanical properties of the bricks were analysed. Fired waste bricks cause considerable harm to the environment. During production, especially in the firing, transportation and construction procedures, large amounts of bricks are broken and have to be dumped in landfills or used as a filling material. For this purpose, the chemical and mineralogical structures of waste bricks from the orum region in West-Anatolia, Turkey, were investigated. After pulverizing, the samples were divided into two categories: A passing through a 4.75 mm sieve (coarse) and B passing a 600 μm sieve (fine). In order to obtain comparable test results, ratios of the waste (0, 10, 20 and 30% by mass) were added to the raw-brick clay. Standard test methods were used to determine the mechanical properties of the bricks at different firing temperatures. The results show that at a mass of 30% fine-waste material additive, fired at 900°C, the test sample has an adequate strength. The reuse of this material in the industry would contribute to the protection of farmland and the environment.     

Calcium and sulphur distribution in fired clay brick in the presence of a black reduction core using micro X-ray fluorescence mapping

A new finding of the observation of an elemental gradient or zoning of calcium and sulphur in fired brick bodies is described, that does not appear to have been reported in the literature before. Many raw clays used in brickmaking and pottery contain sulphur and calcium evenly distributed in low amounts in the unfired clay body. However, when the clay body is fired in the kiln at 1050 °C, the elements sulphur and calcium appear to combine to a compound, most probably calcium sulphate. The formation of calcium sulphate, visualised using energy dispersive imaging micro X-ray fluorescence (μ-XRF), only occurs around a so-called reduction core, also known as ‘black core’, caused by reduced magnetite Fe₃O₄ in the centre of the brick body. The presence of a black reduction core appears to cause the formation of a calcium sulphate layer around the black reduction core. This research contributes to the understanding of phenomena like salt formation, efflorescence and durability in solid clay brick bodies. Large sums are spent on building conservation by national economies and improvement of bricks is of key interest to them.     

An investigation on the production of construction brick with processed waste tea

The main objective of this study is to investigate the utilization potential of processed waste tea (PWT) in clay brick. The effects of processed waste tea material addition on the durability and mechanical properties of the bricks were investigated. Due to the organic nature of PWT, pore-forming (in fired body) and binding (unfired body) ability in clay body was investigated. First, PWT material was dispersed in water for 24 h. Afterwards, in order to get comparable results, different ratios of the waste (0, 2.5, and 5% by mass) were added to the raw-brick clay. Test specimens were produced by the extrusion method. The samples were tested by using the standard test methods and compared with the specifications. The compressive strength of the unfired and fired samples significantly increased as compared to pure samples. As a result, it was concluded that PWT can be utilized in unfired and fired building bricks by taking advantage of low cost and environmental protection.     

城市污泥生产烧结砖试验研究

由于印染污泥、市政污泥、河涌污泥等均含有一定热值,既是制砖原料,也是燃料,经“泥水一体化”脱水工艺将水分脱至55%左右,按比例加入页岩、炉渣等,充分练泥混合、采用高挤出压力、高真空度和低成型含水率的双级真空硬塑挤出机制出砖坯,烘干处理、烧制后制成市政用砖.     

Properties of bricks incorporating unground rice husks

This paper deals with the incorporation of unground rice husks into hand-made, kiln-fired bricks such as are made in developing countries. Bricks with a range of rice husk contents were prepared and then fired in either a small electric test kiln or a commercial Hoffman kiln. The following properties of the bricks were measured: density, compressive strength, modulus of rupture, water absorption and initial rate of absorption. The conclusion drawn is that it is possible to incorporate to 50% rice husks (by volume of clay) into bricks without causing brick properties to fall outside limits acceptable in developing countries.     

Manufacture of high heat conductivity resistant clay bricks containing perlite

Different methods have been investigated for achieving heat insulation in the buildings. Manufacturing of high heat conductivity resistant construction materials is an important part of these research efforts. Perlite is an extremely useful material for heat insulation and 70% of the world reserves are located in Turkey. Nearly 65% of the perlite produced today is consumed by the construction industry. Its thermal, lightness, and acoustic insulation properties make perlite an excellent material to be used as lightweight aggregate in brick manufacturing. High heat resistant brick can be produced by adding perlite into the clay in conventional brick manufacturing. In this investigation perlite of Eski?ehir region and clay were collated and fired to form high heat conductivity resistant material. Binding materials such as cement, gypsum, lime, bitumen and clay were used for manufacturing perlite brick. Bricks in standard sizes manufactured at different perlite–clay ratios and unit weight, compressive strength, volume reduction and heat conductivity values were obtained. Then the mixture with the best combination of the properties was determined and cost optimization was described. Results were examined according to combination properties, and specialties of perlite bricks were determined at various weights. As a result, the best mixture was determined as the one containing 30% perlite.     

Applications of sewage sludge ash and nano-SiO2 to manufacture tile as construction material

In this study, various portions of potter’s clay and porcelain clay were replaced with incinerated sewage sludge ash (ISSA) to manufacture sludge ash tile specimens. We used these tiles to investigate the effect of introducing nano-SiO₂ particles as strengthening additives in the clay–ISSA materials. Percentages of ISSA in the porcelain or potter’s clay-based materials ranged from 0% to 50%, and fractions of nano-SiO₂ additives range from 0% to 3%. Tile specimens were manufactured from the different clay–ISSA–additive mixtures and sintered at kiln temperatures of 1000 °C and 1100 °C. Mechanical tests were performed to measure shrinkage, water absorption, abrasion, and bending strength. The sample microstructure was investigated using scanning electron microscopy (SEM). Chemical compositions of the tile specimens were characterized with X-ray diffraction. Results indicate that water absorption of porcelain and potter’s clay-based tiles was reduced when samples were fired at the higher kiln temperature, dropping to less than 12% in porcelain tiles at a kiln temperature of 1100 °C. Kiln temperature appeared to have less influence on the tiles made from potter’s clay. With the addition of nano-SiO₂ additive, the bending strengths of both types of tiles were increased, with the strengthening effect more pronounced in potter’s clay tiles when compared to porcelain clay tiles.     

Use of boron waste as a fluxing agent in production of red mud brick

The study was directed towards determining the usability of clay and fine wastes (CW and FW) of boron from the concentrator plant in Kirka (Turkey) as a fluxing agent in production of red mud (RM) brick. Both laboratory studies on the characterization of materials and industrial-scale tests for production of bricks were carried out. CW and FW, which have similar chemical composition but include different types and amounts of oxides, were added in amounts of 5, 10 and 15 wt% to RM, which consists of high amounts of Fe₂O₃, Al₂O₃, SiO₂ and alkalies. Six different sets of samples have been produced and fired at 700, 800 and 900 °C. Dry shrinkage of green body, bending and compressive strength, firing shrinkage, water absorption, frost resistance and harmful magnesia and lime tests on heat-treated bodies have been performed. The mineralogical and mechanical tests showed that usability of boron wastes as a fluxing agent in the production of RM bricks was possible. In addition, the samples obtained by adding 15 wt% CW and FW to RM showed the best mechanical characteristic.