Firing temperature and firing time influence on mechanical and physical properties of clay bricks
Abstract and Figures
The effects of firing time and temperature on compressive strength, water absorption, bending strength, weight loss, firing shrinkage and densities of clay bricks were determined. For a given clay and method of manufacture, higher compressive and bending strengths, higher density and lower absorptions are associated with higher firing temperatures. Increasing firing time only slightly altered the mechanical and physical properties of clay bricks. However, firing temperature significantly affected the physical properties. The results suggested that firing temperature was the key factor to modulate the physical properties in clay bricks. However, the effect of firing time was not significant. The results obtained in this study can only be compared to the properties of bricks produced under similar conditions with similar raw materials.
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... The total duration of the firing process was 8 hours before cooling the samples down (turning the furnace off). This procedure was similar to some previous studies which can be found elsewhere (Karaman et al., 2006;Hoang and Nguyen, 2017;dos Reis et al., 2020) in which the drying process needs to be carried out before firing stage to avoid the bloating of the samples at high temperature, caused by the expansion of entrapped water. Even at the firing stage, the temperature was increased step by step to prevent the bloating of clay due to the formation of an impermeable vitrified outer skin preventing the loss of water vapour and CO2 from the interior of the clay (Karaman et al., 2006). ...
... This procedure was similar to some previous studies which can be found elsewhere (Karaman et al., 2006;Hoang and Nguyen, 2017;dos Reis et al., 2020) in which the drying process needs to be carried out before firing stage to avoid the bloating of the samples at high temperature, caused by the expansion of entrapped water. Even at the firing stage, the temperature was increased step by step to prevent the bloating of clay due to the formation of an impermeable vitrified outer skin preventing the loss of water vapour and CO2 from the interior of the clay (Karaman et al., 2006). ...
This study partially replaced the clay with sewer sludge (SS) and rice husk (RH-SS) to make fired bricks. The brick samples were examined in terms of shrinkage, water absorption, and compressive strength. Besides, they were analysed via XRD and metal extraction to determine the heavy metal residuals in the products. The results showed that it was possible to fabricate fired bricks using sewer sludge or rice husk-blended sludge with up to 30% by weight. These brick samples complied with the technical standard for clay brick production, in which the compressive strength was more than 10 MPa, water absorption was from 11-16%, and the linear shrinkage was all less than 5%. The rice husk addition helped mitigate the heavy metal residuals in the bricks and leachate, in which all the values were lower than the US-EPA maximum concentration of contaminants for toxicity characteristics.
... For all the samples, as the value of the compressive strain increases, the compressive stress also increases. It is expected that the compressive strength of the samples would increase with increasing sintering temperature possibly due to decrease in sample porosity, increase in bulk density [29]. The formation of glassy (amorphous) phases is also believed to contribute to the higher compressive strength of the samples As the amount of feldspar present in the samples increases, the compressive strengths initially increase without a corresponding increase in the compressive strain before failure of the sample. ...
... The possible explanation for this is that feldspar which contains high amount of SiO2 melts at relatively lower temperature and therefore acts as a flux. The molten phases which are formed tend to fill the pores, and decrease the porosity which causes the increase in bulk density of the porcelain body leading to the initial increase in compressive strength [29,31]. The sample made from the composition with 80 wt. ...
Dental porcelain was produced by mixing feldspar, silica, kaolin and bone ash by varying the contents of feldspar and silica. The processing steps include milling, sieving, pressing/shaping, drying, and sintering while the characterisation techniques were Hardness, Compressive strength, X-ray diffraction, Scanning electron microscopy and Fourier Transform Infrared (FTIR). The mixture was subjected to temperatures of 1100 and 1200 oC in a sintering furnace. The chemical composition was determined using X-ray fluorescence and they confirm that SiO2 and Al2O3 are the two major constituents in feldspar and kaolin while CaO is the major constituent in bone ash. For samples sintered at 1200oC, the X-ray diffraction showed that some glass phase possibly consisting of hedenbergite, ilmenite and silica were formed while crystalline phases namely microcline and sanidine were obtained for samples sintered at 1100°C. The morphology of the grains revealed that samples sintered at 1200oC had some hexagonal silica crystals while flakes of different sizes were obtained for samples sintered at 1100oC. Hardness values between 262 and 536 BHN, compressive modulus values ranging from 219 MPa to 324 MPa and linear shrinkage values between 6.34 and 7.6% were obtained. The batches of different compositions with ranges: quartz (silica) (15-25%), feldspar (70-80%), kaolin (Edda/Bauchi) (4%) and bone ash (1%) were fired at 1100, 1200oC, and the developed properties were tested. The sample with 70 wt.% of feldspar, 25 wt.% silica, 4 wt.% of Bauchi clay, and 1 wt.% bone ash sintered at 1200oC gave the best properties and has the potential to be used in dental restoration.
... Usumacinta sediments bricks were fired at a temperature range of 700 to 1100 ℃. This is a common temperature range in brick kilns and research studies [18,30,31] and is achievable by burning agro-waste. The manufacturing steps of fired bricks are shown in Figure 3. ATG analysis of Usumacinta River sediments shows that during the firing of bricks, breakdown of carbonates occurs around 700 ℃ which releases CaO that reacts with free silica and alumina. ...
Reuse of dredged sediments is an effective approach to waste management. This study focuses on the reuse of Usumacinta River dredged sediments in fired bricks. Physico-chemical characteristics of sediments were investigated for their reuse. The grain size of sediments shows that Usumacinta sediments have a sandy texture with low organic matter. The presence of contaminants in these sediments is negligible. Suitability for bricks was observed with a clay workability chart, Winkler, and Augustinik diagram. Bricks were molded into cubic and prismatic brick specimens of size 20 × 20 × 20 mm³ and 15 × 15 × 60 mm³ for compressive and tensile strength. The molding moisture content of sediments was defined with the Sembenelli diagram. Bricks were dried at 60 ℃ and fired at a temperature of 700 to 1100 ℃. Linear shrinkage and density of Usumacinta sediments bricks increase with increasing temperature. Clayey sediments (T2 and J4) show higher shrinkage on drying. Testing of bricks shows their compressive strength varies between 0.10 to 19.38 MPa and the indirect tensile strength varies from 0.17 to 12.82 MPa. T2 sediment bricks have the lowest strength due higher percentage of sand. The compressive strength of bricks from T5 and J4 is comparatively higher and satisfies the strength requirements of bricks at a moderate temperature of 850 ℃.
... It is known that increasing the firing temperature increases the compressive strength (density), but very high temperatures also affect the increase in energy consumption, so the temperature was chosen on a realistic scale according to brick production technology. The heating rate is an important parameter because if the temperature rises quickly, the brick can inflate because a glass-like outer membrane forms, preventing the release of gases (CO 2 and water vapour) from inside the brick [37]. The firing conditions were also adapted to the technology of the brick manufacturer in order to conduct future tests on a real scale. ...
The influence of combustion temperature on the properties of sewage sludge ash (SSA) as a substitute material for the production of fired clay bricks was studied. The experiments were performed with sewage sludge (SS) from wastewater treatment plants (WWTP) in Zagreb (ZG) and Karlovac (KA). SS samples were fired at temperatures of 800, 900 and 1000 ◦C, and the properties of the resulting SSA were determined and compared with clay and SS. Bricks with 5 wt% SSA as clay substitute were prepared and compared with clay bricks (control). SSA bricks produced at higher temperatures are of higher strengths and lower water absorption, which are both desirable properties. Compressive strength tests showed that SSA obtained at a firing temperature of 900 ◦C is the most suitable for use in bricks. For the first time, the influence of SSA on the content of soluble salts in bricks was tested. The content of soluble salts, expressed by the electrical conductivity of leachate, in SSA bricks showed increased values compared to the control bricks, which were 2.8 and 4.6 times higher in bricks with SSA produced at 800 ◦C. Still, bricks with SSA prepared at higher temperatures had lower content of soluble salts and also SSA from KA had lower soluble salts content than SSA from ZG. The total amount of Na+, K+, Mg2+in all bricks made with SSA was below the limits for category S2 according to EN 771-1.
... The amount of organic and moisture content remains in increasing order with LSD percentage increment as shown in Table 3. These organic contents as well as chemically or mechanically bound water got combusted during the burning of bricks at 1000 • C which results in an increasing rate of shrinkage [45]. Trapped air or gases inside the LSD-incorporated brick evaporated during burning at high temperatures, though high shrinkage is unsatisfactory for the burning of any weather. ...
In the tannery, after sammying and splitting, the flesh side of wet-blue leather is shaved getting a uniform thickness known as shaving. During shaving, a significant amount of chromium-containing leather shaving dust (LSD) is generated. It affects the environment and the management of chromium-containing LSD is a great challenge. In this work, LSD is used in brick production mitigating the generated solid waste in a tannery. The LSD (w/w) of 0%, 2%, 3%, 4%, 5%, 6%, and 7% are incorporated along with clay and burned at 1000 ◦C in the brickfield. The outcome discloses 4% LSD amended brick showed the maximum engineering and chemical properties. The optimum 4% LSD amended brick’s weight loss, shrinkage area, water absorption, compressive strength, and efflorescence properties to be 11.38%, 5.51%, 14.26%, 10.69 N/mm2, and no efflorescence, respectively. The Scanning Electron Microscope (SEM) images denote the micro-fibrous structure of the composite that played a significant role in producing lightweight brick. The NEN 7345 leaching test of the LSD-incorporated bricks indicated that leached metals were below the acceptable limit. Utilization of LSD will open an eye as an ingredient in brick production, to mitigate tannery solid waste load.
... Instead of open shelters, modern dryers provide full control over the environment during the drying phase [72]. Kiln technology has also advanced, enabling bricks to be fired at higher temperatures, resulting in increased mechanical strength [73]. The current standard brick dimension is 215 × 102.5 × 65 mm [74], and a range of products with different compression strengths and durability is available on the market to cater for various needs [75]. ...
This study presents a comprehensive review of building materials, construction methods, and building regulations on the U.K. mainland. This provides valuable insights into the historical progression and transformation of the construction industry through a comprehensive analysis of both traditional and modern building construction materials and methods and categorising their evolutionary trajectory. Current building regulations in England, Wales, and Scotland are compared, highlighting differences in fire safety, noise safety, energy conservation, and sustainability. For example, fire safety regulations are analysed in detail, including fire resistance duration, wall cladding combustibility, and limitations on unprotected areas. Advances in knowledge and technology have led to increasingly sophisticated and energy-dependent methods, materials, and regulations. This study showcases the vast array of building construction materials spanning centuries, each possessing unique properties and performances. The selected methods and materials represent those currently employed or widely utilised in the U.K. construction industry, affirming their relevance and applicability in modern construction practices. Limitations in construction practices primarily stem from a lack of knowledge and tools rather than material scarcity. Enhancing knowledge and access to advanced tools is crucial to overcoming these limitations and driving advancements in the field. This study provides insights into the evolution of building materials, construction methods, and building regulations that can inform future developments in sustainable building practices. The findings have significant implications for policymakers, building designers, and constructors, particularly in terms of adopting sustainable materials and construction methods that comply with building regulations while reducing the environmental impact of the built environment.
Around the world, large amounts of plastic and glass waste have been collected. This work is given as a way to reduce this material. This paper aims to investigate how fired clay bricks' physical and mechanical properties are affected by plastic/glass ( P/G) powder. It is used as a replacement for clay, varying the plastic/glass content 00/20, 05/15, 10/10, 15/05, and 20/00 weight %. The ratio of soil to water remains constant 0.3. The maximum temperature is presented after three fire phases. The temperatures are 300 °C for the first, 600 °C for the second, and 900 °C for the third. Results for the physical properties showed an increase in the water absorption of clay brick specimens as the plastic content increased; in addition, efflorescence was increased with plastic powder. However, the density and firing shrinkage decrease with plastic quantity. Also, the experimental results showed a decrease in water absorption and efflorescence when the glass powder was increased. While the density is higher when glass powder is 20 %. According to the findings on mechanical properties, clay brick samples with higher plastic powder content 20 % displayed a decrease in compressive strength and flexural bending strength, i. e. the mechanical properties (compressive and flexural strengths) are increased with the increased
South Africa, like many other developing nations, faces significant challenges in delivering effective and fair public services. Africa in particular suffers from a catastrophic shortage of public infrastructure, and a variety of factors contribute to the infrastructure deficit. Public entities around the world are battling with effective service delivery and have adopted different models to enhance and improve infrastructure delivery. However, the models currently deployed have shortcomings, thus frustrating the efforts to deliver infrastructure effectively to the general populace. South Africa has similarly had its fair share of false starts. The 2010 introduction of Infrastructure Delivery Management System (IDMS) was specifically to facilitate effective, timely and sustained infrastructure development, and tackle the challenges in public sector infrastructure delivery. The study employs a multi-case study, qualitative approach through content analysed data to look at four nations that implements infrastructure projects in Europe and Sub-Saharan Africa and analyze the advancement of infrastructure delivery. A systematic review of infrastructure delivery models/reforms in the context of public sector was carried out through literature and descriptive analysis was applied. The findings reveal a knowledge vacuum about the diverse techniques taken by various countries in the execution of public sector infrastructure projects, and provide little precise evidence on the performance of delivery systems and lessons learned. It is here recommended that interventions such as IDMS should be contextualized cognizant of the country’s developmental imperatives.KeywordsReformsInfrastructureDeliveryConstruction industryPublic sector
This paper considers the need for a clear legal and policy framework to guide a more sustainable construction industry and the use of digital technologies. It commences with an analysis of the meaning of sustainable development and briefly reflects on the three components of sustainable construction industry. The paper argues that while much has been written on the environmental aspect there has been more limited engagement with the social component of sustainable development. It critically analyses decent work deficits in the construction industry and the role of law and technology in addressing these deficits. In so doing it follows a doctrinal and legal research methodology. The paper argues that while the benefits of certain digital technologies for safer construction industry are undeniable, there is not much certainty on the extent to which the construction industry is legally obligated to adopt such technologies. Ultimately, it considers that codes on corporate social responsibility could play a valuable role where they operate alongside clear legal frameworks to guide the construction industry in the adoption of such technological tools. These technological tools are then to be used as part of a broader commitment to promoting a sustainable construction industry in which there is decent work for all. It concludes with recommendations for legal reform to guide a more sustainable construction industry.KeywordsSustainable developmentDecent workOccupational health and safetySocial insuranceSocial protection
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.
Bricks manufactured from dried sludge collected from an industrial wastewater treatment plant were investigated. Results of tests indicated that the sludge proportion and the firing temperature were the two key factors determining the brick quality. Increasing the sludge content results in a decrease of brick shrinkage, water absorption, and compressive strength. Results also showed that the brick weight loss on ignition was mainly attributed to the organic matter content in the sludge being burnt off during the firing process. With up to 20% sludge added to the bricks, the strength measured at temperatures 960 and 1000 °C met the requirements of the Chinese National Standards. Toxic characteristic leaching procedure (TCLP) tests of brick also showed that the metal leaching level is low. The conditions for manufacturing good quality bricks is 10% sludge with 24% of moisture content prepared in the molded mixtures and fired at 880–960 °C.
During investigations of failures of brick, the relation among water absorption, interior fissures (i. e. typical delaminations associated with the clay extrusion process), and microstructure of the brick was studied by using ASTM procedures and optical and scanning electron microscopy. As a result of this testing, the relation betwen 24-h submersion and 5-h boiling absorption was estimated, and brick were separated into groups. The typical types of interior fissures and microstructures of samples of each group are discussed.
The state-of-the-art of brick, making in Asia was studied and it was found that in many countries the industry is using energy inefficiently. Experiments determining the effects of firing temperature and firing time on the mechanical properties of the brick were carried out. The firing time does not affect the compressive strength and water absorption properties. Higher firing temperature increases the compressive strength but has no affect on the water absorption. It was found that the minimum firing temperature for clay-brick transformation is 600 degreesC. The specific energy is in the range of 569-966 kJ/kg brick for the firing temperature between 600 and 900 degreesC. The mechanical properties of four-hole hollow bricks with 7 different hole sizes were studied. The production of light brick (high area to mass ratio) is suggested in order to reduce the energy consumption without significant loss of mechanical properties.
Mineralogical transformations caused by firing, of five different compositions used in the formulation of ceramic pastes have been studied. Test samples have been prepared by extrusion and fired in the range of 900–1150°C. Analysis of the fired samples was carried out by optical microscopy. The presence of enstatite, gehlenite, hercynite and mullite and abundant vitreous phase showed neomineralization. A fluid texture was present in all the samples and phenocrysts occurred in the partially microcrystalline matrix. In this way, the ceramic ware was analogous to porhyritic type rocks, with quartz phenocrystals and a typical undulating liquidation, opaque minerals such as hematites and crystalloblastic quartz structures on grains of orthoclase. The samples with low carbonate contents were composed of bulky particles, predominantly of quartz and hematites, which are agglomerated in a vitreous matrix.
Investigations were undertaken to assess the thermal modification in clay products from alluvial deposits of the Indo–Gangetic plains of India. Typical alluvial clay materials from three locations were evaluated for physico-chemical, mineralogical and brick making attributes. Briquette samples (5.0×2.5×2.5 cm3) were fired at 700, 800, 900, 1000 and 1100°C and micro-crystalline mineral phases were identified through the XRD technique. No major alteration in mineral structure of constituent mineral specie takes place up to a firing temperature of 850°C except dehydroxylation of kandite/mica mineral. The skeleton lattice structure of muscovite/mica mineral was found to exist in samples fired to ∼900°C. The development of strength and reduction in porosity of the clay product from these clay materials were noticed at elevated temperatures due to enhanced vitrification.
This paper is a report on the results of a feasibility study on the immobilisation of tannery sludge by producing a ceramic product. The main purpose of this work was to test the clays used in the manufacture of a ceramic that could incorporate tannery sludge. The raw materials, tannery sludge and clay, were mixed together in different proportions. The ceramic specimens were characterised with respect to water absorption, porosity, linear shrinkage and transverse rupture strength. Leaching tests, in accord with the Brazilian and German regulations, were done on ceramic bodies made with different additions of sludge. In order to evaluate the possibility of air contamination during the firing process, preliminary studies of air emissions were carried out The mechanical properties of the samples evaluated were similar to those specified for ceramic bricks. All the leaching tests have shown that the main sludge contaminant i.e. chromium, could be immobilised within a finished ceramic product. The studies of air emissions have shown that zinc and chlorine are mainly collected from gas emissions and hence are not immobilised by the ceramic system. The study shows that the properties of the ceramic materials produced are acceptable for applications such as bricks for the building industry.
This work represents an effort to study the improvement of physical and mechanical properties of some Cameroonian lateritic soil bricks by stabilization through heat (at very low temperatures), with a view to finding their suitability for the construction of walls of simple houses. Contrary to previous studies which were focused on stabilization with additives (lime, cement, bentonite, etc.), no admixture is used here. The effect of homogenization obtained by crushing raw materials to reduce particle size, the cohesion of clay present in raw materials and the cementitious binder resulting from the transformation of some mineral phases at low temperatures have been exploited. The laboratory test results are promising.
Influence of mineralogy and firing temperature on the porosity of bricks
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Interior fissures and microstructure of shale brick
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