This paper reports the modeling of residual compressive strength of fired clay bricks submitted to elevated temperature. Five formulations were used and the explored temperatures were 95˚C, 200˚C, 550˚C, 700˚C and 950...This paper reports the modeling of residual compressive strength of fired clay bricks submitted to elevated temperature. Five formulations were used and the explored temperatures were 95˚C, 200˚C, 550˚C, 700˚C and 950˚C. The stress–strain relationships and the mechanical properties (including Young’s modulus and compressive strength) were assessed using a uniaxial compressive strength machine. A proposed model equation was established and found satisfying. The elastic modulus was evaluated and tested with one existing model together with two proposed models. The proposed model was both satisfying and even more precise than the existing one. The overall results show that the effect of temperature on the mechanical properties of clays can be accurately described through the definition of thermal damage using elastic modulus.展开更多
This article deals with the characterization of local materials used in insulation building heat. These materials are bricks of earth compressed and stabilized with rice husks. Thermal conductivity, the specific heat ...This article deals with the characterization of local materials used in insulation building heat. These materials are bricks of earth compressed and stabilized with rice husks. Thermal conductivity, the specific heat and the thermal diffusivity of materials based on clay incorporating rate of 0, 2%, 4%, 6%, 8% and 10% are determined. The results showed that the clay blocks + rice balls had better thermal insulators than simple clay blocks. However, these composite materials used for the envelope of the building must have sufficient mechanical resistance when used in construction. The measurement of mechanical properties such as compressive strength showed an improvement of 6% and beyond, a drop in resistance when increasing rice husks in clay is observed. These results allow to specify the optimal conditions of use of these materials for the building envelope.展开更多
Clay brick masonry unit(CBMU) walls are widely used in building structures,and its damage and protection under explosion loads have been a matter of concern in the field of engineering protection.In this paper,a serie...Clay brick masonry unit(CBMU) walls are widely used in building structures,and its damage and protection under explosion loads have been a matter of concern in the field of engineering protection.In this paper,a series of full-scale experiments of the response characteristics of 24 cm CMBU walls unreinforced and reinforced with polyurea elastomer subjected to blast loading were carried out.Through setting 5.0 kg TNT charges at different stand-off distances,the damage characteristics of masonry walls at different scaled distances were obtained.The reinforcement effect of different polyurea coating thicknesses and methods on the blast resistance performance of masonry walls under single and repeated loads were also explored.Five failure grades were summarized according to the dynamic response features of masonry walls.Based on the stress wave propagation pattern in multi-media composite structures,the internal stress distribution of masonry walls were analyzed,and the division basis of the masonry walls’ failure grades was then quantified.Combined with Scanning Electron Microscope(SEM)images,the deformation characteristics of soft and hard segments of polyurea and effects of detonation products on microstructures were revealed respectively,which provides an important reference for the design and application of polyurea in the blast resistance of clay brick masonry walls.展开更多
Clay materials from Thicky in Thiès district (Senegal) are very abundant and could be used for the production of clay brick for the construction industry in Senegal and the surrounding countries. The geophysical,...Clay materials from Thicky in Thiès district (Senegal) are very abundant and could be used for the production of clay brick for the construction industry in Senegal and the surrounding countries. The geophysical, geotechnical, and thermal studies carried out did lead to a better comprehension of the potential of the area for clay production. It also allowed determining the physical and chemical characteristics of the clays for their use in order to make fired clay bricks. Different types of fired clay brick were produced with Thicky’s clays. The study of the physical, mechanical and thermal parameters of these raw materials and bricks has given very satisfactory results compared to the standards in use. It is noted a good ceramic behavior, and there is no deterioration observed after firing at 900°C until low residual moisture of about 3% (on a dry basis), a smooth texture with a beautiful appearance, a low loss on ignition, a low shrinkage value of less than 1% (dry), moderate water absorption and also good compressive strength. The study of thermal properties on a brick wall by the asymmetric lime plane method gives satisfactory effusivity and thermal conductivity values which are respectively equal to 746.48 J<span style="white-space:nowrap;"><span style="white-space:nowrap;">·</span></span>K<sup>-1</sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">·</span></span>m<sup>-2</sup><span style="white-space:nowrap;">·</span>s<sup>-1/2</sup> and 0.42 W<span style="white-space:nowrap;"><span style="white-space:nowrap;">·</span></span>m<sup>-1</sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">·</span></span>k<sup>-1</sup> with a thermal resistance of 0.0028 m<sup>2</sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">·</span></span>K<span style="white-space:nowrap;"><span style="white-space:nowrap;">·</span></span>W<sup>-1</sup>.展开更多
The cartography and characterization of an alluvial clay deposit from Ebebda (Central region of Cameroon) were carried out in order to assess its suitability for the production of fired clay bricks. The clayey area in...The cartography and characterization of an alluvial clay deposit from Ebebda (Central region of Cameroon) were carried out in order to assess its suitability for the production of fired clay bricks. The clayey area investigated is ~ 50,000 m2 with an average thickness of the exploitable layer of 2.2 m, suggesting a deposit of about ~2.2 × 105 tonnes of clay. Mineralogy, physico-chemical and thermal analyses as well as firing properties were performed on representative clay samples. Kaolinite and quartz are the major minerals associated to illite. Upon heating to 900℃ - 1200℃, the linear shrinkage varies from 1.5% to 15%, the water absorption from 1.5% to 24% and the bending strength from 2 to 12 MPa. The admixture of lateritic clays (widely available) at 50%, 60%, 70% and 80% allow to decrease the shrinkage and bending strength, and to increase the water absorption. Overall, properties were satisfying the requirement for fired brick with 70% of laterite in the mixture.展开更多
This work has presented the evaluation of the compressive strength of hybrid clay bricks from interlocking brick making machine. The mixture of clay and cement at varying proportions was loaded into the mould compartm...This work has presented the evaluation of the compressive strength of hybrid clay bricks from interlocking brick making machine. The mixture of clay and cement at varying proportions was loaded into the mould compartment, mechanically rammed and hydraulically controlled. The raw clay was sourced from Ilesa and Akure in the south-western part of Nigeria. The results showed that when the cement content was 6%, the highest compressive load and energy at break were obtained in hybrid bricks from both Ilesa and Akure samples. However, the optimum service performance under compressive loading was attained at 6% cement in Ilesa hybrid bricks. Ilesa hybrid bricks possess better reliability and workability under loading than the Akure bricks.展开更多
Particle size analysis, Atterberg limits, X-ray diffraction, X-ray fluorescence and firing tests were used to determine physico-chemical, mineralogical and technological characteristics of residual lateritic (K1M, Ma2...Particle size analysis, Atterberg limits, X-ray diffraction, X-ray fluorescence and firing tests were used to determine physico-chemical, mineralogical and technological characteristics of residual lateritic (K1M, Ma2) and alluvial (KB3, KG3) clays from Foumban (West-Cameroon). For technological properties, the samples were pressed and fired over a temperature range of 900°C - 1200°C to determine the open porosity, linear shrinkage, bulk density and compressive strength. Kaolinite (31% - 65%) and quartz (35% - 50%) are dominant in Foumban clays with accessory K-feldspar, plagioclase, illite, smectite, rutile, and goethite. But their proportion changes from one sample to another, having a significant effect on the behaviour of the clay materials: highest proportion of quartz (50%) in sample K1M;relative high feldspars (20%) and illite contents (10%) in KB3 and MA2;high smectite content in KG3 (up to 20%). Chemical analyses indicate high SiO2 (49% - 77%) and low Al2O3 (14% - 23%) contents in the four samples, with comparatively low contents of iron oxides (4% - 7% in samples KB3 and KG3, 2.5% in MA2 and ~1.5% in sample K1M). The particle size distribution of the alluvial clays (KG3 and KB3) differs considerably: 7% to 37% of clay fraction, 20% to 78% of silt, and 15% to 58% of sand, while residual clays (K1M and MA2) present on average 12% of clay, 51% of silt and 37% of sand. Two raw clays (KB3 and MA2) can be used for bricks/tiles production without beneficiation or addition. K1M requires some flux addition to decrease the sintering temperature while KG3 presents poor properties due to the combined occurrence of smectite and a high clayey fraction (37%). Such mineralogical composition is responsible for very high plasticity (PI: 50), high shrinkage (LS: 5% - 16%), low porosity (OP: up to 21%) and high flexural strength (FS: 16 - 23 N/mm2) above 1050°C. This last clay is therefore less appropriate for bricks and roofing tiles production since degreasers must be added to the raw material.展开更多
An experimental study was carried out on bricks using local materials in order to take into account the waste wood management to protect the environment and to reduce the cost of the habitat. Chips and sawdust were bu...An experimental study was carried out on bricks using local materials in order to take into account the waste wood management to protect the environment and to reduce the cost of the habitat. Chips and sawdust were built-in clay bricks in order to study their influence on the compressive strength, Young’s modulus and the speed for soundproofing. Testings in compressive strength were made on the parallelepiped clay bricks, stabilized with different percentages of cement, with incorporation to various percentages of sawdust or wood chips (Mahogany), using a universal press. Young’s modulus was measured from the speed of sound by the ultrasonic method. The results obtained show that the incorporation of mahogany tree chips in the stabilized brick at 8% of cement, does not have much effect on the compressive strength. It was found that the incorporation of chips or sawdust on the clay brick, does not improve the compressive strength. The Young’s modulus decreases with increasing content of sawdust and practically remains constant regardless of the content of chips at 4% and 6% of cement. The clay brick mixed with 8% of mahogany sawdust can be an acoustic barrier.展开更多
High cost has been pointed among factors that limit the promotion of geopolymers. To contribute to the reduction of the use of costly industrial sodium silicate in activators for geopolymers, a gel obtained with RHA a...High cost has been pointed among factors that limit the promotion of geopolymers. To contribute to the reduction of the use of costly industrial sodium silicate in activators for geopolymers, a gel obtained with RHA and concentrated sodium hydroxide was used in the present study to develop an alkaline activator with 8 M NaOH and to produce geopolymers with crushed fired clay bricks wastes (FCBW). Characteristics of the gel were compared to that of commercial sodium silicate which was also mixed with 8 M NaOH in the ratio 1:1 to produce geopolymers. Chemical and mineralogical analyses were done on raw materials. Fourier Transformed Infrared Spectroscopy (FTIR) was done on the gel, commercial sodium silicate and products. Biaxial four point flexural strength, bulk density, water absorption and scanning electron microscopy (SEM) tests were also done on products. Results showed that RHA-NaOH alkaline activator has good potential in consolidating FCBW powder through geopolymerization process which gave products that had characteristics not far from that when the commercial sodium silicate was used. The gel obtained by mixing RHA and NaOH can contribute to the reduction of the use of costly commercial sodium silicate in the production process of geopolymers. However, appropriate filtration process is needed for the RHA-NaOH gel to reduce its impurities as undissolved entities, which will consequently contribute to improve the flexural strength, the density and the microstructure of its products which were low compared to when commercial sodium silicate was used.展开更多
This study focuses on the valuation and optimization of local materials to meet the challenge of sustainable development. Faced with climate change and the preservation of the environment, research into eco-materials ...This study focuses on the valuation and optimization of local materials to meet the challenge of sustainable development. Faced with climate change and the preservation of the environment, research into eco-materials is necessary to reduce the energy bill while ensuring comfort and safety. The objective is to make a comparative characterization of the physico-mechanical properties of compressed earth bricks made from local materials: clay, laterite and sand. These are, on the one hand, bricks made from clay and laterite, reinforced with a percentage of sand varying between 20<span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">%</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> and 30% in steps of 5%., were made. On the other hand, these same mixtures stabilized with 5% cement (CEM II-32.5) are also used to produce bricks. A characte</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">rization of the raw materials was made before studying the physi</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">co-mechanical properties of the bricks themselves. This involved evaluating the water absorbency and compressive strength of stabilized and unstabilized bricks. The results show that the absorptivity of stabilized clay bricks is ac</span></span></span></span><span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">ceptable up to </span><span style="font-family:Verdana;">25% sand because it is less than </span></span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">the </span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">15% maximum value set by Cameroonian standard NC-104: 2002-06. However, that of stabilized laterite bricks is higher than the maximum value set by the standard. The compressive strengths, for clay bricks stabilized with 5% cement and for laterite bricks with 0% sand added, are all greater than 2 MPa and therefore are acceptable. In addition, clay bricks with 20% sand and stabilized with 5% cement are recommended because they have the most optimal physico-mechanical properties.</span></span></span></span>展开更多
Thatch fibres grow in large quantity in the Adamawa region of Cameroon. During the long dry season, these fibres cause numerous fire incidents, which not only devastate large areas of cash crops, but also contribute t...Thatch fibres grow in large quantity in the Adamawa region of Cameroon. During the long dry season, these fibres cause numerous fire incidents, which not only devastate large areas of cash crops, but also contribute to increase emissions of greenhouse gases into the atmosphere. This article aims to show how fibres could be used with compressed clay bricks to manufacture an insulating material used in building. Four fibre contents 1%, 2%, 3% and 4% made up the sample studied. The asymmetric hot plate methodology was used to determine the thermophysical properties of these composite materials. The volumetric heat capacity and the thermal effusivity of these materials were estimated. These two parametres were used to determine their apparent thermal conductivities. The results obtained show that the thermal conductivity decreases as the volume of fibres in the mixture increases. It is 0.689 W·m-1·K-1 for simple compressed clay bricks and 0.510 W·m-1·K-1 for a dosage at 3% of thatch fibres. In a bit to validate the results of the pilot study of the apparent thermal conductivity, the heat mass capacity of this composite material was achieved through the use of the dehydration method. The relative difference obtained with the results of the volumetric heat capacity carried out with these two methods was good. All results showed that the use of fibres in compressed laterite brick gives a more insulating composite material that respects Civil Engineering Norms.展开更多
The aim of this study is to search for a substitute for the natural coarse aggregate in various regions of the world, such as Amazon-Brazil, where this type of material is lacking. The asphalt binder AC 50/70 is mixed...The aim of this study is to search for a substitute for the natural coarse aggregate in various regions of the world, such as Amazon-Brazil, where this type of material is lacking. The asphalt binder AC 50/70 is mixed with an aggregate obtained from the sinterization of a calcined clay (SACC) as a possible alternative to coarse aggregate material for the construction of asphalt pavements in tropical zones. The dynamic modulus |E*| of this mixture was measured under strain control mode and in tension control mode. The results are compared with those obtained from AC 50/70 mixed with pebbles, which is currently used as the coarse aggregate in this region. For pavements that work at high temperatures, such as 40℃, and low frequencies, the mixture with SACC appears to be a viable alternative to coarse aggregate material for the construction of asphalt pavements in tropical zones.展开更多
Coal is used as a traditional fuel for firing of clay bricks in kilns. The cost of coal is high and is increasing continuously. This paper describes the effect of alternate fuels on compressive strength, water absorpt...Coal is used as a traditional fuel for firing of clay bricks in kilns. The cost of coal is high and is increasing continuously. This paper describes the effect of alternate fuels on compressive strength, water absorption and density of fired clay bricks. The alternate fuels used in this study were 1) rapeseed husk (Type I), 2) combination of sugarcane-bagasse, rice husk and used clothes (Type II) and 3) coal (Type III). The results show that compressive strength of bricks fired using Type I and Type II fuels was decreased to 11% and 7%, respectively, compared to those fired with coal. However, the values of water absorption and density of bricks fired with Type I and Type II fuels were almost same as exhibited by those baked with coal. This study shows that a saving of 25%, and 18% could be achieved when the bricks were fired using Type I and Type II fuels, respectively, compared to those fired with coal.展开更多
The current study deals Swith thermo-mechanical properties of stabilized soil small bricks with the help of organic binders of sugar cane molasses and cassava starch. Different formulations of soil concrete have been ...The current study deals Swith thermo-mechanical properties of stabilized soil small bricks with the help of organic binders of sugar cane molasses and cassava starch. Different formulations of soil concrete have been suggested after the geotechnical characterization of samples of soil was taken. From these, it arises that the studied soil is the most plastically clay (of type A<sub>3</sub>) according to GTR classification. Samples made of small bricks and measured out at 4%, 6% and 8% of binders (molasses, starch or molasses + starch) have been warmed up to different temperatures (100°C, 150°C, 200°C and 250°C) for the rising of the thermic behavior under different conditions and submitted to crushing testings for the estimation of characteristic resistances to the compression. According to the mechanical behavior, we note an improvement of resistances for small bricks measured 4%, 6% and 8%, of molasses respectively of 32.44%, 32.06% and 23.43% against the value of reference for small bricks without molasses. In the same way, the binder (molasses + starch) also reveals an improvement of resistance to the compression of 13.27%, 26.17% and 26.17%. On the contrary, the stabilization with the starch binder did not bring a significative improvement. According to the thermic influence, the heating at 100°C of stabilized small bricks at 4%, 6% and 8% of molasses, reveals a significative improvement of resistances. Moreover, the stabilization with the starch reveals on the contrary a good behavior for heatings at 150°C and 250°C. In short, for the binder (molasses + starch), it is the heating at 200°C that shows some improvements of remarkable resistances. Different analyses of realized statistics also show the effectivity of obtained results. For all realized formulations, the measuring out at 6% of binders (molasses, or molasses + starch) seems as optimal in front of the best thermo-mechanical revealed properties.展开更多
This paper presents an experimental study of the characterisation of local materials used in the construction and thermal insulation of buildings. These materials are compressed earth bricks stabilised with cement and...This paper presents an experimental study of the characterisation of local materials used in the construction and thermal insulation of buildings. These materials are compressed earth bricks stabilised with cement and sawdust. The thermal conductivity, diffusivity, effusivity, and specific heat of earth-based materials containing cement or sawdust have been determined. The results show that the blocks with earth + sawdust are better thermal insulators than the blocks with simple earth. We observe an improvement in thermal efficiency depending on the presence of sawdust or cement stabilisers. For cement stabilisation, the thermal conductivity increases (λ: 1.04 to 1.36 W·m<sup>-1</sup>·K<sup>-1</sup>), the diffusivity increases (from 4.32 × 10<sup>-7</sup> to 9.82 × 10<sup>-7</sup> m<sup>2</sup>·s<sup>-1</sup>), and the effusivity decreases (1404 - 1096 J·m<sup>-2</sup>·K<sup>-1</sup>·s<sup>-1/2</sup>). For sawdust stabilisation, the thermal conductivity decreases (λ: 1.04 to 0.64 W·m<sup>-1</sup>·K<sup>-1</sup>), the diffusivity increases (from 4.32 × 10<sup>-7</sup> to 5.9 × 10<sup>-7</sup> m<sup>2</sup>·s<sup>-1</sup>), and the effusivity decreases (1404 - 906 J·m<sup>-2</sup>·K<sup>-1</sup>·s<sup>-1/2</sup>). Improving the structural and thermal efficiency of BTC via stabilisation with derived binders or cement is beneficial for the load-bearing capacity and thermal performance of buildings.展开更多
文摘This paper reports the modeling of residual compressive strength of fired clay bricks submitted to elevated temperature. Five formulations were used and the explored temperatures were 95˚C, 200˚C, 550˚C, 700˚C and 950˚C. The stress–strain relationships and the mechanical properties (including Young’s modulus and compressive strength) were assessed using a uniaxial compressive strength machine. A proposed model equation was established and found satisfying. The elastic modulus was evaluated and tested with one existing model together with two proposed models. The proposed model was both satisfying and even more precise than the existing one. The overall results show that the effect of temperature on the mechanical properties of clays can be accurately described through the definition of thermal damage using elastic modulus.
文摘This article deals with the characterization of local materials used in insulation building heat. These materials are bricks of earth compressed and stabilized with rice husks. Thermal conductivity, the specific heat and the thermal diffusivity of materials based on clay incorporating rate of 0, 2%, 4%, 6%, 8% and 10% are determined. The results showed that the clay blocks + rice balls had better thermal insulators than simple clay blocks. However, these composite materials used for the envelope of the building must have sufficient mechanical resistance when used in construction. The measurement of mechanical properties such as compressive strength showed an improvement of 6% and beyond, a drop in resistance when increasing rice husks in clay is observed. These results allow to specify the optimal conditions of use of these materials for the building envelope.
基金supported by the National Natural Science Foundation of China nos.51978660。
文摘Clay brick masonry unit(CBMU) walls are widely used in building structures,and its damage and protection under explosion loads have been a matter of concern in the field of engineering protection.In this paper,a series of full-scale experiments of the response characteristics of 24 cm CMBU walls unreinforced and reinforced with polyurea elastomer subjected to blast loading were carried out.Through setting 5.0 kg TNT charges at different stand-off distances,the damage characteristics of masonry walls at different scaled distances were obtained.The reinforcement effect of different polyurea coating thicknesses and methods on the blast resistance performance of masonry walls under single and repeated loads were also explored.Five failure grades were summarized according to the dynamic response features of masonry walls.Based on the stress wave propagation pattern in multi-media composite structures,the internal stress distribution of masonry walls were analyzed,and the division basis of the masonry walls’ failure grades was then quantified.Combined with Scanning Electron Microscope(SEM)images,the deformation characteristics of soft and hard segments of polyurea and effects of detonation products on microstructures were revealed respectively,which provides an important reference for the design and application of polyurea in the blast resistance of clay brick masonry walls.
文摘Clay materials from Thicky in Thiès district (Senegal) are very abundant and could be used for the production of clay brick for the construction industry in Senegal and the surrounding countries. The geophysical, geotechnical, and thermal studies carried out did lead to a better comprehension of the potential of the area for clay production. It also allowed determining the physical and chemical characteristics of the clays for their use in order to make fired clay bricks. Different types of fired clay brick were produced with Thicky’s clays. The study of the physical, mechanical and thermal parameters of these raw materials and bricks has given very satisfactory results compared to the standards in use. It is noted a good ceramic behavior, and there is no deterioration observed after firing at 900°C until low residual moisture of about 3% (on a dry basis), a smooth texture with a beautiful appearance, a low loss on ignition, a low shrinkage value of less than 1% (dry), moderate water absorption and also good compressive strength. The study of thermal properties on a brick wall by the asymmetric lime plane method gives satisfactory effusivity and thermal conductivity values which are respectively equal to 746.48 J<span style="white-space:nowrap;"><span style="white-space:nowrap;">·</span></span>K<sup>-1</sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">·</span></span>m<sup>-2</sup><span style="white-space:nowrap;">·</span>s<sup>-1/2</sup> and 0.42 W<span style="white-space:nowrap;"><span style="white-space:nowrap;">·</span></span>m<sup>-1</sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">·</span></span>k<sup>-1</sup> with a thermal resistance of 0.0028 m<sup>2</sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">·</span></span>K<span style="white-space:nowrap;"><span style="white-space:nowrap;">·</span></span>W<sup>-1</sup>.
文摘The cartography and characterization of an alluvial clay deposit from Ebebda (Central region of Cameroon) were carried out in order to assess its suitability for the production of fired clay bricks. The clayey area investigated is ~ 50,000 m2 with an average thickness of the exploitable layer of 2.2 m, suggesting a deposit of about ~2.2 × 105 tonnes of clay. Mineralogy, physico-chemical and thermal analyses as well as firing properties were performed on representative clay samples. Kaolinite and quartz are the major minerals associated to illite. Upon heating to 900℃ - 1200℃, the linear shrinkage varies from 1.5% to 15%, the water absorption from 1.5% to 24% and the bending strength from 2 to 12 MPa. The admixture of lateritic clays (widely available) at 50%, 60%, 70% and 80% allow to decrease the shrinkage and bending strength, and to increase the water absorption. Overall, properties were satisfying the requirement for fired brick with 70% of laterite in the mixture.
文摘This work has presented the evaluation of the compressive strength of hybrid clay bricks from interlocking brick making machine. The mixture of clay and cement at varying proportions was loaded into the mould compartment, mechanically rammed and hydraulically controlled. The raw clay was sourced from Ilesa and Akure in the south-western part of Nigeria. The results showed that when the cement content was 6%, the highest compressive load and energy at break were obtained in hybrid bricks from both Ilesa and Akure samples. However, the optimum service performance under compressive loading was attained at 6% cement in Ilesa hybrid bricks. Ilesa hybrid bricks possess better reliability and workability under loading than the Akure bricks.
文摘Particle size analysis, Atterberg limits, X-ray diffraction, X-ray fluorescence and firing tests were used to determine physico-chemical, mineralogical and technological characteristics of residual lateritic (K1M, Ma2) and alluvial (KB3, KG3) clays from Foumban (West-Cameroon). For technological properties, the samples were pressed and fired over a temperature range of 900°C - 1200°C to determine the open porosity, linear shrinkage, bulk density and compressive strength. Kaolinite (31% - 65%) and quartz (35% - 50%) are dominant in Foumban clays with accessory K-feldspar, plagioclase, illite, smectite, rutile, and goethite. But their proportion changes from one sample to another, having a significant effect on the behaviour of the clay materials: highest proportion of quartz (50%) in sample K1M;relative high feldspars (20%) and illite contents (10%) in KB3 and MA2;high smectite content in KG3 (up to 20%). Chemical analyses indicate high SiO2 (49% - 77%) and low Al2O3 (14% - 23%) contents in the four samples, with comparatively low contents of iron oxides (4% - 7% in samples KB3 and KG3, 2.5% in MA2 and ~1.5% in sample K1M). The particle size distribution of the alluvial clays (KG3 and KB3) differs considerably: 7% to 37% of clay fraction, 20% to 78% of silt, and 15% to 58% of sand, while residual clays (K1M and MA2) present on average 12% of clay, 51% of silt and 37% of sand. Two raw clays (KB3 and MA2) can be used for bricks/tiles production without beneficiation or addition. K1M requires some flux addition to decrease the sintering temperature while KG3 presents poor properties due to the combined occurrence of smectite and a high clayey fraction (37%). Such mineralogical composition is responsible for very high plasticity (PI: 50), high shrinkage (LS: 5% - 16%), low porosity (OP: up to 21%) and high flexural strength (FS: 16 - 23 N/mm2) above 1050°C. This last clay is therefore less appropriate for bricks and roofing tiles production since degreasers must be added to the raw material.
文摘An experimental study was carried out on bricks using local materials in order to take into account the waste wood management to protect the environment and to reduce the cost of the habitat. Chips and sawdust were built-in clay bricks in order to study their influence on the compressive strength, Young’s modulus and the speed for soundproofing. Testings in compressive strength were made on the parallelepiped clay bricks, stabilized with different percentages of cement, with incorporation to various percentages of sawdust or wood chips (Mahogany), using a universal press. Young’s modulus was measured from the speed of sound by the ultrasonic method. The results obtained show that the incorporation of mahogany tree chips in the stabilized brick at 8% of cement, does not have much effect on the compressive strength. It was found that the incorporation of chips or sawdust on the clay brick, does not improve the compressive strength. The Young’s modulus decreases with increasing content of sawdust and practically remains constant regardless of the content of chips at 4% and 6% of cement. The clay brick mixed with 8% of mahogany sawdust can be an acoustic barrier.
文摘High cost has been pointed among factors that limit the promotion of geopolymers. To contribute to the reduction of the use of costly industrial sodium silicate in activators for geopolymers, a gel obtained with RHA and concentrated sodium hydroxide was used in the present study to develop an alkaline activator with 8 M NaOH and to produce geopolymers with crushed fired clay bricks wastes (FCBW). Characteristics of the gel were compared to that of commercial sodium silicate which was also mixed with 8 M NaOH in the ratio 1:1 to produce geopolymers. Chemical and mineralogical analyses were done on raw materials. Fourier Transformed Infrared Spectroscopy (FTIR) was done on the gel, commercial sodium silicate and products. Biaxial four point flexural strength, bulk density, water absorption and scanning electron microscopy (SEM) tests were also done on products. Results showed that RHA-NaOH alkaline activator has good potential in consolidating FCBW powder through geopolymerization process which gave products that had characteristics not far from that when the commercial sodium silicate was used. The gel obtained by mixing RHA and NaOH can contribute to the reduction of the use of costly commercial sodium silicate in the production process of geopolymers. However, appropriate filtration process is needed for the RHA-NaOH gel to reduce its impurities as undissolved entities, which will consequently contribute to improve the flexural strength, the density and the microstructure of its products which were low compared to when commercial sodium silicate was used.
文摘This study focuses on the valuation and optimization of local materials to meet the challenge of sustainable development. Faced with climate change and the preservation of the environment, research into eco-materials is necessary to reduce the energy bill while ensuring comfort and safety. The objective is to make a comparative characterization of the physico-mechanical properties of compressed earth bricks made from local materials: clay, laterite and sand. These are, on the one hand, bricks made from clay and laterite, reinforced with a percentage of sand varying between 20<span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">%</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> and 30% in steps of 5%., were made. On the other hand, these same mixtures stabilized with 5% cement (CEM II-32.5) are also used to produce bricks. A characte</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">rization of the raw materials was made before studying the physi</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">co-mechanical properties of the bricks themselves. This involved evaluating the water absorbency and compressive strength of stabilized and unstabilized bricks. The results show that the absorptivity of stabilized clay bricks is ac</span></span></span></span><span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">ceptable up to </span><span style="font-family:Verdana;">25% sand because it is less than </span></span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">the </span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">15% maximum value set by Cameroonian standard NC-104: 2002-06. However, that of stabilized laterite bricks is higher than the maximum value set by the standard. The compressive strengths, for clay bricks stabilized with 5% cement and for laterite bricks with 0% sand added, are all greater than 2 MPa and therefore are acceptable. In addition, clay bricks with 20% sand and stabilized with 5% cement are recommended because they have the most optimal physico-mechanical properties.</span></span></span></span>
文摘Thatch fibres grow in large quantity in the Adamawa region of Cameroon. During the long dry season, these fibres cause numerous fire incidents, which not only devastate large areas of cash crops, but also contribute to increase emissions of greenhouse gases into the atmosphere. This article aims to show how fibres could be used with compressed clay bricks to manufacture an insulating material used in building. Four fibre contents 1%, 2%, 3% and 4% made up the sample studied. The asymmetric hot plate methodology was used to determine the thermophysical properties of these composite materials. The volumetric heat capacity and the thermal effusivity of these materials were estimated. These two parametres were used to determine their apparent thermal conductivities. The results obtained show that the thermal conductivity decreases as the volume of fibres in the mixture increases. It is 0.689 W·m-1·K-1 for simple compressed clay bricks and 0.510 W·m-1·K-1 for a dosage at 3% of thatch fibres. In a bit to validate the results of the pilot study of the apparent thermal conductivity, the heat mass capacity of this composite material was achieved through the use of the dehydration method. The relative difference obtained with the results of the volumetric heat capacity carried out with these two methods was good. All results showed that the use of fibres in compressed laterite brick gives a more insulating composite material that respects Civil Engineering Norms.
文摘The aim of this study is to search for a substitute for the natural coarse aggregate in various regions of the world, such as Amazon-Brazil, where this type of material is lacking. The asphalt binder AC 50/70 is mixed with an aggregate obtained from the sinterization of a calcined clay (SACC) as a possible alternative to coarse aggregate material for the construction of asphalt pavements in tropical zones. The dynamic modulus |E*| of this mixture was measured under strain control mode and in tension control mode. The results are compared with those obtained from AC 50/70 mixed with pebbles, which is currently used as the coarse aggregate in this region. For pavements that work at high temperatures, such as 40℃, and low frequencies, the mixture with SACC appears to be a viable alternative to coarse aggregate material for the construction of asphalt pavements in tropical zones.
文摘Coal is used as a traditional fuel for firing of clay bricks in kilns. The cost of coal is high and is increasing continuously. This paper describes the effect of alternate fuels on compressive strength, water absorption and density of fired clay bricks. The alternate fuels used in this study were 1) rapeseed husk (Type I), 2) combination of sugarcane-bagasse, rice husk and used clothes (Type II) and 3) coal (Type III). The results show that compressive strength of bricks fired using Type I and Type II fuels was decreased to 11% and 7%, respectively, compared to those fired with coal. However, the values of water absorption and density of bricks fired with Type I and Type II fuels were almost same as exhibited by those baked with coal. This study shows that a saving of 25%, and 18% could be achieved when the bricks were fired using Type I and Type II fuels, respectively, compared to those fired with coal.
文摘The current study deals Swith thermo-mechanical properties of stabilized soil small bricks with the help of organic binders of sugar cane molasses and cassava starch. Different formulations of soil concrete have been suggested after the geotechnical characterization of samples of soil was taken. From these, it arises that the studied soil is the most plastically clay (of type A<sub>3</sub>) according to GTR classification. Samples made of small bricks and measured out at 4%, 6% and 8% of binders (molasses, starch or molasses + starch) have been warmed up to different temperatures (100°C, 150°C, 200°C and 250°C) for the rising of the thermic behavior under different conditions and submitted to crushing testings for the estimation of characteristic resistances to the compression. According to the mechanical behavior, we note an improvement of resistances for small bricks measured 4%, 6% and 8%, of molasses respectively of 32.44%, 32.06% and 23.43% against the value of reference for small bricks without molasses. In the same way, the binder (molasses + starch) also reveals an improvement of resistance to the compression of 13.27%, 26.17% and 26.17%. On the contrary, the stabilization with the starch binder did not bring a significative improvement. According to the thermic influence, the heating at 100°C of stabilized small bricks at 4%, 6% and 8% of molasses, reveals a significative improvement of resistances. Moreover, the stabilization with the starch reveals on the contrary a good behavior for heatings at 150°C and 250°C. In short, for the binder (molasses + starch), it is the heating at 200°C that shows some improvements of remarkable resistances. Different analyses of realized statistics also show the effectivity of obtained results. For all realized formulations, the measuring out at 6% of binders (molasses, or molasses + starch) seems as optimal in front of the best thermo-mechanical revealed properties.
文摘This paper presents an experimental study of the characterisation of local materials used in the construction and thermal insulation of buildings. These materials are compressed earth bricks stabilised with cement and sawdust. The thermal conductivity, diffusivity, effusivity, and specific heat of earth-based materials containing cement or sawdust have been determined. The results show that the blocks with earth + sawdust are better thermal insulators than the blocks with simple earth. We observe an improvement in thermal efficiency depending on the presence of sawdust or cement stabilisers. For cement stabilisation, the thermal conductivity increases (λ: 1.04 to 1.36 W·m<sup>-1</sup>·K<sup>-1</sup>), the diffusivity increases (from 4.32 × 10<sup>-7</sup> to 9.82 × 10<sup>-7</sup> m<sup>2</sup>·s<sup>-1</sup>), and the effusivity decreases (1404 - 1096 J·m<sup>-2</sup>·K<sup>-1</sup>·s<sup>-1/2</sup>). For sawdust stabilisation, the thermal conductivity decreases (λ: 1.04 to 0.64 W·m<sup>-1</sup>·K<sup>-1</sup>), the diffusivity increases (from 4.32 × 10<sup>-7</sup> to 5.9 × 10<sup>-7</sup> m<sup>2</sup>·s<sup>-1</sup>), and the effusivity decreases (1404 - 906 J·m<sup>-2</sup>·K<sup>-1</sup>·s<sup>-1/2</sup>). Improving the structural and thermal efficiency of BTC via stabilisation with derived binders or cement is beneficial for the load-bearing capacity and thermal performance of buildings.
