Firing temperature and firing time influence on mechanical and physical properties of clay bricks
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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 water absorption capacity and compressive strength vary greatly as per the type of kiln used and the position of bricks inside the kiln during the firing process (Laefer et al., 2004;Subedi, 2020). Also, the compressive strength increased and water absorption capacity decreased with an increase in firing temperature (Karaman et al., 2006;Tsega et al., 2017). Clay bricks' compressive strength increases slightly with increased fire time while their ability to absorb water decreases Tsega et al. (2017); nevertheless, Karaman et al. (2006) observed no significant difference. ...
... Also, the compressive strength increased and water absorption capacity decreased with an increase in firing temperature (Karaman et al., 2006;Tsega et al., 2017). Clay bricks' compressive strength increases slightly with increased fire time while their ability to absorb water decreases Tsega et al. (2017); nevertheless, Karaman et al. (2006) observed no significant difference. The strength and durability of bricks depend on their physical and mechanical properties. ...
... After heating to 200 o C, the bricks lost most of the water added to the samples during the preparation phase. Drying was carried out when the moisture content of the molded bricks was high to prevent the swelling or bloating of the samples, which occurs at high temperatures [13]. The firing operation for the two types of fired bricks was carried out following the procedure mentioned [13]. ...
... Drying was carried out when the moisture content of the molded bricks was high to prevent the swelling or bloating of the samples, which occurs at high temperatures [13]. The firing operation for the two types of fired bricks was carried out following the procedure mentioned [13]. Firing operations were conducted as shown in Figure 6 in a box type muffle resistance electric furnace (Item No: Sx2-2.5-10, ...
The thermal and mechanical properties of two sensible energy storage materials (Firebrick) were investigated. The properties examined were compressive strength, bulk density, porosity and thermal conductivity. The compressive strength results of the two sensible thermal storage materials (STSM) A and B were 8.82 and 9.79 MPa, respectively. The bulk density values for the STSM A and B were 1740 and 1920 kg/m 3 , respectively. Also, the obtained porosity values for the STSM A and B were 77.2 and 71.5%, respectively. The STSM A and B thermal conductivity values were 1.27 and 1.76 W/m.K, respectively. The study revealed that both the STSM A and B are suitable for sensible thermal energy storage purposes.
... Classical brick production requires firing temperatures between 700 and 1100 • C, depending on the clay feedstock and desired quality (e.g., compressive strength). Therefore, low-quality bricks have a compressive strength of 3.5 MPa, regular quality bricks are situated around 6 MPa, and that of first-class bricks is about 10 MPa [18]. It is a matter of the mullitization process occurring at high temperatures. ...
... The literature data show that bricks are commonly fired at about 1000 • C to ensure clay mullitization and the subsequent desired compression strength. The literature shows that the temperature might vary from 700 to 1100 • C depending on the feedstock [18]. Thus, we choose to test our slurry behavior at 700, 800, and 900 • C, which are below the mullitization temperature. ...
The slurry collected from the waste water resulting from ceramic tile processing contains significant amounts of quartz, kaolinite, and mullite, along with traces of iron hydroxides as observed using XRD analysis coupled with mineralogical optical microscopy (MOM). Such an admixture would be ideal for the development of ecologic building materials. Microstructural conditioning enhances the binding properties of kaolinite. Therefore, the influence of the vibration compaction of the moistened slurry at 30% humidity on the compressive strength was assessed. The compressive strength of the unvibrated sample is about 0.8 MPa with failure promoted by the microstructural unevenness. Several vibration amplitudes were tested from 20 to 40 mm. The optimal vibration mode was obtained at an amplitude of 25 mm for 10 min, ensuring a compressive strength of 2.37 MPa with a smooth and uniform failure surface involved within the binding layer as observed using SEM microscopy. The samples prepared under optimal conditions were thermally consolidated at 700, 800, and 900 °C below the mullitization temperature to ensure a low carbon footprint. XRD results reveal kaolinite dehydration in all fired samples, inducing its densification, which increases with increasing heating temperature. SEM coupled with EDS elemental investigations reveal that the dehydrated kaolinite better embeds quartz and mullite particles, ensuring a compact microstructure. The binding strength increases with the firing temperature. The mullite particles within the samples fired at 900 °C induce the partial mullitization of the dehydrated kaolinite matrix, increasing their homogeneity. The compression strength of the fired samples is temperature dependent: 4.44 MPa at 700 °C; 5.88 MPa at 800 °C, and 16.87 MPa at 900 °C. SEM fractography shows that failure occurs due to the dehydrated kaolinite matrix cracks and the quartz particles. The failure is rather plastic at low temperatures and becomes brittle at 900 °C. Reducing the firing temperature and treatment time reduces the carbon footprint of the consolidated ceramic parts. Samples fired at 700 °C exhibit a compressive strength comparable to low quality bricks, those fired at 800 °C exhibit a strength comparable to regular bricks, and those fired at 900 °C exhibit a superior strength comparable to high-quality bricks.
... (2) optimizing raw material formulations, particularly in determining the optimal marble powder (MWP) dosage and firing regime to balance porosity development and bloating risks; (3) scaling up production processes for industrial applications-our planned tests will systematically evaluate the maximum MWP incorporation levels before defect formation, temperature thresholds for controlled decarbonation, and firing cycle modifications to facilitate gradual CO 2 release [53,54]; and (4) assessing long-term durability under diverse environmental conditions. These efforts will ensure the safe, widespread adoption of this sustainable building material, supporting greener construction practices. ...
Nowadays, the global brick industry utilizes billions of cubic meters of clay soil annually, resulting in the massive consumption of non-renewable resources. This study explores the viability of utilizing red marl from phosphate mining waste rocks for fired brick production. Ecofriendly fired bricks produced from 100% side streams (red marly clays (RM) and marble waste powder (MWP)) were prepared, pressed, dried at 105 • C, and then fired at 1100 • C for 1 h. The effects of marble waste powder addition (up to 30 wt%) on the physical, mechanical, mineralogical, and microstructural properties of the fired bricks were explored. The main results show that fired bricks with high compressive strength of a maximum of 39 MPa could be prepared with a mixture of red marl and 10 wt% of marble waste powder. The thermal conductivity was decreased by marble waste addition (from 0 to 30%) and was reduced from 0.93 W/m.k to 0.53 W/m.k; however, the compressive strength was also decreased to reach a minimum of 17 MPa. The firing shrinkage and density were also reduced with 30% marble waste by 41% and 18%, respectively. Therefore, red marly clays and marble waste could be promising raw materials for eco-fired brick production.
... (2) optimizing raw material formulations, particularly in determining the optimal marble powder (MWP) dosage and firing regime to balance porosity development and bloating risks; (3) scaling up production processes for industrial applications-our planned tests will systematically evaluate the maximum MWP incorporation levels before defect formation, temperature thresholds for controlled decarbonation, and firing cycle modifications to facilitate gradual CO 2 release [53,54]; and (4) assessing long-term durability under diverse environmental conditions. These efforts will ensure the safe, widespread adoption of this sustainable building material, supporting greener construction practices. ...
Nowadays, the global brick industry utilizes billions of cubic meters of clay soil
annually, resulting in the massive consumption of non-renewable resources. This study explores the viability of utilizing red marl from phosphate mining waste rocks for fired brick production. Ecofriendly fired bricks produced from 100% side streams (red marly clays (RM) and marble waste powder (MWP)) were prepared, pressed, dried at 105 ◦C, and then fired at 1100 ◦C for 1 h. The effects of marble waste powder addition (up to 30 wt%) on the physical, mechanical, mineralogical, and microstructural properties of the fired bricks were explored. The main results show that fired bricks with high compressive strength of a maximum of 39 MPa could be prepared with a mixture of red marl and 10 wt% of marble waste powder. The thermal conductivity was decreased by marble waste addition (from 0 to 30%) and was reduced from 0.93 W/m.k to 0.53 W/m.k; however, the compressive strength
was also decreased to reach a minimum of 17 MPa. The firing shrinkage and density were also reduced with 30% marble waste by 41% and 18%, respectively. Therefore, red marly clays and marble waste could be promising raw materials for eco-fired brick production.
... While the results of studies on earth may be highly specific re: raw materials used, research conducted by Karaman, Ersahin, and Gunal and Tsega demonstrate the impact of firing duration and temperature on earthen material properties. 5 The authors demonstrate that firing temperature significantly influences mechanical properties of the material; higher firing temperatures result in increased strengths and density, and decreased water absorption and weight loss. In contrast, variations in firing time have less pronounced effects on these properties. ...
Drawing on the vernacular wisdom and craftsmanship of cyclical architectural typologies such as Iranian pigeon towers, this research explores graded durability and planned obsolescence in earthen construction. The study advocates for incorporating graded durability in the design and production of interlocking compressed earth blocks leading to a predictable/planned decay and obsolescence in the lifecycle of earthen block structures. This involved subjecting compressed earth blocks with various geometries and firing methods to natural/ environmental decay agents as means to explore, observe, and understand rate of decay. The observational outcomes were used in the design of durability-graded compressed earth blocks. In recent years, the construction industry has faced increasing scrutiny over its environmental footprint, particularly concerning the widespread use of concrete. Concrete plays a critical role in contemporary construction, not only as a primary component but also in the stabilization of earthen materials and as a binding agent in cement-based mortars for assembling structures made from earthen blocks. The research presented here attempts to mitigate the adverse environmental impacts traditionally associated with the building industry. Instead of striving for maximum durability through the incorporation of cement – which comes at a significant environmental cost – the explored method tailors and grades durability in earthen blocks to meet specific construction and programmatic needs without compromising environmental sustainability and cyclicality of the building material. Ultimately, this material and structural exploration could lead to the development of environmentally conscious practices that anticipate building lifecycle through controlled decay, expanding on traditional knowledge while enhancing efficiency in terms of materials, labor, and time. The sample-informed study that is the basis for this exploration combines the vernacular wisdom and craftsmanship of existing cyclical architectural typologies with contemporary technologies, resulting in sustainable and culturally rich architectural proposals. These vernacular heritage precedents show a resourceful attitude in response to specific environmental conditions of their context through tectonics, materiality, and functionality.
Infill walls are essential in all types of buildings as they reduce the effect of lateral forces. Many materials, such as bricks, stones, hollow core blocks, precast blocks, and fly ash bricks, are used in infill walls. This study aims to develop an eco-friendly, sustainable, and durable interlocking brick. Geopolymer bricks were preferred in this regard to impart the eco-friendly effect, as geopolymers have low embodied carbon. Industrial wastes such as ground Granulated Blast Furnace Slag (GGBS) and coir fibers were used to induce sustainability. The geopolymer binder was made using GGBS and activator solutions: sodium hydroxide (NaOH) and Sodium Silicate (NaSi2O3). Geopolymer interlocking earth blocks of size 9″ × 8″ × 5″ were made, and the GIEB mix's proportions consisted replacement of red soil with GGBS at 0%, 5%, 10%, 15%, 20%, 25%, with constant fiber addition of 0.5% in the soil. The tests conducted for interlocking blocks include dry and wet compressive strength, water absorption, and ultrasonic pulse velocity tests. From the experimental investigation results, it was observed that the strength gains of about 20% were obtained by GGBS and fiber additions. Mix with 20% GGBS and 0.5% coir fiber showed higher strengths of 28.03 MPa and 19.02 MPa in the dry and wet states, respectively. It was also found that the embodied carbon and embodied energy values were lower for the GIEB compared with the conventional blocks.
The present study aimed to investigate the feasibility of recycled soil for manufacturing burnt clay bricks by replacement of natural soil (NS). Recycled soil (RS) is the by-product generated during the processing of construction and demolition waste. The physicochemical properties of raw clay soil and recycled soil were examined using various laboratory procedures such as chemical analysis, index properties of soil, compaction etc. Six different NS+RS mixtures (0, 10, 20, 30, 40 and 50% by weight) were combined with clay soil. In this study, fly ash and lime were utilized to improve the performance of the mix as well as the firmness and density of the combined material. Bricks were cast in three separate groups. (1) NA+RS free of additives (2) NA+RS with 10% fly ash; (3) NA+RS with 5% fly ash and 5% lime. After casting and drying, controlled and uncontrolled methods were chosen for the burning of bricks. Further, the laboratory evaluation of bricks was done by performing compressive strength, water absorption, efflorescence, and thermal conductivity tests. Results of uncontrolled temperatures burnt bricks showed a maximum 20% replacement of NS having 4.23Mpa compressive strength. While controlled burning allows for 4.09 Mpa compressive strength with 40% soil replacement and 17.13% water absorption. Thus, using RS in clay brick construction is an efficient way to create a porous and lighter brick that meets structural and environmental standards.
The characteristics of the fired bricks change as the firing temperature changes, and this tendency is specific to each clay. In order to understand this trend for clays from the Bhaktapur area of Nepal, test specimens were prepared at different firing temperatures and various properties were measured. The results showed a relationship between firing temperature and density, strength, water absorption, and color, and the possibility that color measurement could be useful in diagnosing brick quality.
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.
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