The use of soil as a construction material is limited due to climatic conditions such as rain and wind effects. The valorization of industrial and agricultural by-products in soil-material-based composites for constru...The use of soil as a construction material is limited due to climatic conditions such as rain and wind effects. The valorization of industrial and agricultural by-products in soil-material-based composites for construction materials is an alternative to producing eco-materials for building construction. This study evaluates the effect of Shea Butter residue (SBr) and hydrated lime (HL) as stabilizers on the performance of Compressed Earth Blocks (CEB). For the production of CEB specimens, firstly the dry mixtures were prepared using soil material and 5 wt% HL, 5% - 25% wt% SBr and secondly, the appropriate amount of water was thoroughly mixed with the dry mixtures using the result of the proctor compaction test. All the moistened mixtures were mechanically pressed into CEBs on mold size (29.5 cm × 14 cm × 9.5 cm), cured at ambient temperature in the lab for 0 - 45 days, and dried at 60˚C for 7 days before being tested. The results give for the accessible porosity, bulk density, maximum dry and wet compressive strength, the respective value 31.58%;1580 kg/cm2;3.26 MPa and 0.75 MPa for CEB stabilized with 5 wt% lime without SBr. Moreover, the abrasion coefficient (14.49 cm2/g), the mass lost (0.08%), the surface depth (3.25 mm/h), the eroded surface (9.12 cm2), the sorptivity (0.046 g/cm2·min1/2 the absorption by total immersion at 2 h and 24 h (4.06 and 11.94%) are best for the CEBs stabilized with 5/5 wt% HL/SSBr. However, the lower thermal properties were obtained with CEB stabilized with 25 wt% SSBr. We therefore observe the significant reaction between these industrial and agricultural by-products with the earth material, with effects particularly on the hydric, thermal and durability properties. The use of industrial and agricultural by-products such as lime and SBr at an appropriate rate of 5 wt% are suitable to improve CEBs performances.展开更多
Coral sand is a unique material developed in the tropical ocean environment, which is mainly composed of coral and other marine organism debris, with the CaCO3 content up to 96 %. It has special physical and mechanica...Coral sand is a unique material developed in the tropical ocean environment, which is mainly composed of coral and other marine organism debris, with the CaCO3 content up to 96 %. It has special physical and mechanical properties due to its composition, structure and sedimentary environment. In this contribution, we discuss its specific gravity, porosity ratio compressibility, crushing, shearing and intensity for coral sand samples from the Nansha islands based on laboratory mechanical tests. Our results show distinct high porosity ratio, high friction angle and low intensity as compared with the quartz sand. We believe that grain crushing is the main factor that influences the deformation and strength of coral sand. Comprehensive study on the physical and mechanical properties of coral sands is significant in providing reliable scientific parameters to construction on coral islet, and thus avoids accidents in construction.展开更多
We studied the effects of nanoparticles of organo-silane（NOS） compounds in the size range of20–80 nm on physical and mechanical properties in medium density fiberboard,and used NOS at four consumption levels of 0,5...We studied the effects of nanoparticles of organo-silane（NOS） compounds in the size range of20–80 nm on physical and mechanical properties in medium density fiberboard,and used NOS at four consumption levels of 0,50,100,and 150 g kg-1dry wood fibers.Density of all treatments was kept constant at 0.67 g cm-3.The water-repellent property of organo-silane significantly reduced water absorption（WA） and thickness swelling but mechanical properties declined due to the reduced proportion of wood-fiber as organo-silane was added to the matrix：the compression ratio of MDF panels and the integrity among wood-fibers both declined,resulting in reduced mechanical properties.We recommend use of 50 g of NOS/kg wood-fiber to improve WA and thickness swelling while retaining acceptable mechanical properties.展开更多
In deep-earth engineering,the high earth temperature can significantly affect the rock's mechanical properties,especially when the rock is cooled during the construction process.Accordingly,whether the cooling spe...In deep-earth engineering,the high earth temperature can significantly affect the rock's mechanical properties,especially when the rock is cooled during the construction process.Accordingly,whether the cooling speed affects the mechanical and physical properties of rocks is worth to be investigated.The present study explored the influence of the cooling rate on the physical and chemical properties of granite heated at 25–800°C.The mechanical and physical properties involved in this study included uniaxial compression strength,peak strain,modulus,P-wave velocity,mass and volume,the change of which could reflect the sensitivity of granite to the cooling rate.Acoustic emission(AE)monitoring,microscopic observation,and X-ray diffraction(XRD)are used to analyze the underlying damage mechanism.It is found that more AE signals and large-scale cracks are accounted for based on the b-value method when the specimens are cooled by water.Furthermore,the microscopic observation by polarized light microscopy indicates that the density,opening degree,and connectivity of the cracks under water cooling mode are higher than that under natural cooling mode.In addition,the XRD illustrates that there is no obvious change in mineral content and diffraction angle at different temperatures,which confirms that the change of mechanical properties is not related to the chemical properties.The present conclusion can provide a perspective to assess the damage caused by different cooling methods to hot rocks.展开更多
The objective of this investigation was to introduce a cement-based composite of higher quality. For this purpose new hybrid nanocomposite from bagasse fiber,glass fiber and multi-wall carbon nanotubes（MWCNTs）were m...The objective of this investigation was to introduce a cement-based composite of higher quality. For this purpose new hybrid nanocomposite from bagasse fiber,glass fiber and multi-wall carbon nanotubes（MWCNTs）were manufactured. The physical and mechanical properties of the manufactured composites were measured according to standard methods. The properties of the manufactured hybrid nanocomposites were dramatically better than traditional composites. Also all the reinforced composites with carbon nanotube, glass fiber or bagasse fiber exhibited better properties rather than neat cement.The results indicated that bagasse fiber proved suitable for substitution of glass fiber as a reinforcing agent in the cement composites. The hybrid nanocomposite containing10 % glass fiber, 10 % bagasse fiber and 1.5 % MWCNTs was selected as the best compound.展开更多
The artificial afforestation of precious Phoebe bournei has been carried out in China.During the cultivation process,thinning wood will be produced.The properties of thinning wood might vary greatly with matured wood ...The artificial afforestation of precious Phoebe bournei has been carried out in China.During the cultivation process,thinning wood will be produced.The properties of thinning wood might vary greatly with matured wood and require evaluation for better utilization.The objective of the present study aims to determine the wood structure,fiber morphology,and physical and mechanical properties of the Phoebe bournei thinning wood to help us understand the wood properties and improve its utility value.Three 14-year-old Phoebe bournei were cut from Jindong Forestry Farm of Hunan Province,China.The wood structure and fiber morphology were observed and analyzed with a light microscope and scanning electron microscope.The physical and mechanical properties were tested according to the Chinese national standards.The results showed as follows:(1)The Phoebe bournei thinning wood has a beautiful wood figure and fine texture,whereas the heartwood has not yet formed.(2)It is a diffuse-porous hardwood with small and less pores as well as fine wood rays.(3)The wood fiber is medium length and extremely thin wall thickness.(4)It is low in density and has excellent dimensionally stability.(5)The wood mechanical properties belong to the low to medium class and the comprehensive strength of wood belongs to the medium-strength class.It is concluded that Phoebe bournei thinning wood is suitable for wood carving,handicraft,high-end furniture,and decorative furniture parts.展开更多
The use of agricultural waste in construction is an advantage favorable to environmental sanitation, the preservation of non-renewable resources but also to the execution of an ecological work. The objective of this w...The use of agricultural waste in construction is an advantage favorable to environmental sanitation, the preservation of non-renewable resources but also to the execution of an ecological work. The objective of this work is to study the influence of the addition of palm nut cockles ash as an adjuvant on the physico-mechanical properties of concrete. For this study, ordinary concretes and ash concretes were made and subjected to physical and mechanical characterization tests at different maturation periods. The results of the tests carried out indicate that the presence of ash reduces the workability and porosity of the concrete and then increases the density of the concrete to 6.3%. In addition, we found that incorporating the ash improves the mechanical strength of the concrete compared to the control concrete. Thus, the compressive strength of ash concrete is 32.07 MPa and that of splitting is 2.76 MPa at 28 days, which is satisfactory vis-à-vis the threshold of construction projects for ready concrete for use, which recommends a minimum of 25 MPa (compression) and 2.6 MPa (splitting) at 28 days. This improvement in mechanical performance can be attributed to the pozzolanic effect of the constituents of the ash. Therefore, the ash from palm nut shells can be used to improve the mechanical properties of concrete.展开更多
In this paper, the physical and mechanical properties of laminated bamboo lumber were studied by testing moisture content, delamination ratio, horizontal shear strength, MOE and MOR of the structure-use material, in t...In this paper, the physical and mechanical properties of laminated bamboo lumber were studied by testing moisture content, delamination ratio, horizontal shear strength, MOE and MOR of the structure-use material, in the same time, these subjects of finger-joint were tested too. The results showed that, the horizontal shear strength, MOR, MOE of laminated bamboo were superior to the ordinary structure-use timber in architecture, such as Pinus. The performance of aging test was not extraordinary, although the physical and mechanical properties of laminated bamboo lumber decreased after aging test, these properties were beyond Pinus yet.展开更多
This experimental study assesses the effectiveness of traditional and nano-materials in enhancing the physical and mechanical properties of deteriorated sandstone from Ramesses III Temple, Karnak, Luxor, Egypt. Treatm...This experimental study assesses the effectiveness of traditional and nano-materials in enhancing the physical and mechanical properties of deteriorated sandstone from Ramesses III Temple, Karnak, Luxor, Egypt. Treatments included Nano Estel (5%), Paraloid B-72 (3%), Paraloid B-72/Nano Estel (3%/5%), and ethyl silicates. Treated samples underwent Scanning Electron Microscopy (SEM) and physical/mechanical testing. Results show that Paraloid B-72/Nano Estel (3%/5%) yielded optimal consolidation, significantly improving sandstone’s physical and mechanical properties.展开更多
With growing concerns for global warming and environmental issues,the research community has contributed significantly to green technology in the area of material science through the development of natural fiber-reinf...With growing concerns for global warming and environmental issues,the research community has contributed significantly to green technology in the area of material science through the development of natural fiber-reinforced polymer composites(NFRPC).Polymers serve as the matrix in NFRPC,while natural fibers serve as the reinforcing materials.Demand for high-performing materials made with natural resources is growing continuously.Natural fiber-reinforced polymer composites are sustainable biocomposites fabricated with natural fibers embedded with a polymer matrix.They offer a wide range of advantages,including a low weight-to-strength ratio,high flexural strength,damping properties,and resistance to corrosion,wear,and impact.Understanding the basic properties,characteristics,and processing techniques for natural fibers is important to consider their use as raw materials for high-quality biocomposite.Natural fibers come with low density and a high strengthto-weight ratio,allowing them to be a potential reinforcement for low-weight composites.This article attempts to present a comprehensive review of the available natural fibers,their classification,types,structures,physical properties,characteristics,and mechanical properties.Natural fibers are hydrophilic in nature and require physical and chemical treatment prior to their application as reinforcing material.This review will also cover the required physical and chemical treatments of natural fibers for fabricating biocomposites.展开更多
To study the damage mechanisms of anhydrite rock under freeze-thaw cycles, the physicalmechanical properties and the microcracking activities of anhydrite rock were investigated through mass variation, nuclear magneti...To study the damage mechanisms of anhydrite rock under freeze-thaw cycles, the physicalmechanical properties and the microcracking activities of anhydrite rock were investigated through mass variation, nuclear magnetic resonance, scanning electron microscope tests, and uniaxial compression combined with acoustic emission(AE) tests. Results show that with the increase of freeze-thaw processes,the mass, uniaxial compression strength, and elastic modulus of the anhydrite specimens decrease while the porosity and plasticity characteristics increase.For example, after 120 cycles, the uniaxial compression strength and elastic modulus decrease by 46.54% and 60.16%, and the porosity increase by 75%. Combined with the evolution trend of stressstrain curves and the detected events, three stages were labeled to investigate the AE characteristics in freeze-thaw weathered anhydrite rock. It is found that with the increase of freeze-thaw cycles, the proportions of AE counts in stage Ⅰ and stage Ⅱ show a decaying exponential trend. Contrarily, the proportion of AE counts in stage Ⅲ displays an exponential ascending trend. Meanwhile, as the freeze-thaw cycles increase, the low-frequency AE signals increase while the intermediate-frequency AE signals decrease. After 120 cycles, the proportion of low-frequency AE signals increases by 168.95%, and the proportion of intermediate-frequency AE signals reduces by 81.14%. It is concluded that the microtensile cracking events occupy a dominant position during the loading process. With the increase of freeze-thaw cycles, the b value of samples decreases.After 120 cycles, b value decreases by 27.2%, which means that the proportion of cracking events in rocks with small amplitude decreases. Finally, it is proposed that the freeze-thaw damage mechanism of anhydrite is also characterized by the water chemical softening effect.展开更多
Research into the fundamental properties of microcapsules and use of the results to develop a wide variety of products in industries such as printing, fast-moving consumer goods, construction, pharmaceuticals, and agr...Research into the fundamental properties of microcapsules and use of the results to develop a wide variety of products in industries such as printing, fast-moving consumer goods, construction, pharmaceuticals, and agrochemicals is a dynamic and ever-progressing field of study. For microcapsules to be effective in providing protection from harsh environments or delivering large payloads, it is essential to have a good understanding of their properties to enable quality control during formulation, storage, and applications. This review aims to outline the commonly used techniques for determining the physicochemical, struc- tural, and mechanical properties of microcapsules, and highlights the interlinked nature of these three areas with respect to the end-use industrial application. This review provides information on techniques that are well supported in the literature, and also examines microcapsule analytical techniques that will become more prevalent as a result of new technological developments or extensions from other areas of study.展开更多
This study assesses the reactivity of four (04) different types of clayey earthen materials (Kamboinsé, Pabré, Saaba, and Kossodo) with Ca(OH)<sub>2</sub>, analytical lime (AL) versus lime residu...This study assesses the reactivity of four (04) different types of clayey earthen materials (Kamboinsé, Pabré, Saaba, and Kossodo) with Ca(OH)<sub>2</sub>, analytical lime (AL) versus lime residu (LR), in ambient conditions. The effect of the stabilization of the earth with the LR was also studied on the performances of compressed earth blocks (CEB). The lime content varied from 0% to 20% with respect to the mass of dry earth material. The analysis of the reactivity and physico-mechanical properties were respectively carried out on the solutions of the mixtures (earth + LR and earth + AL) and CEB (earth + LR). The mixtures were cured between 0 and 60 days at the ambient temperature of laboratory (30<span style="white-space:nowrap;">℃</span> ± 5<span style="white-space:nowrap;">℃</span>). The results showed that the reactivity of the clayey earth materials with AL is comparable to that with the LR. At the same time, this reactivity improved the physical and mechanical properties of stabilized CEB depending on the type of earth material, lime content and curing time. The maximum values of the dry compressive strength, observed for each material stabilized with 20% LR, are 6 and 7 MPa (Kamboinsé), 8.8 and 9.3 MPa (Pabré), 6 and 6.5 MPa (Saaba), 8.8 and 9.7 MPa (Kossodo) respectively at curing time of 28 and 45 days. The structural efficiency of CEB was also improved which implies that, in the current conditions, the stabilization of earth materials using LR allows to produce the CEB for potential applications in wall masonry.展开更多
In this paper, the authors aim to propose the use of waste plastics as a binder in a coconut shell reinforcement for the development of an 8/6 size composite rafter to replace the natural 8/6 size backbone in construc...In this paper, the authors aim to propose the use of waste plastics as a binder in a coconut shell reinforcement for the development of an 8/6 size composite rafter to replace the natural 8/6 size backbone in construction. Following a study into the choice of the best proportions, a total of 30 size 8/6 composite rafters with different proportions of 20%, 25%, 30%, 35%, 40% and 50% plastic content were developed. All the 8/6 composite rafters were subjected to mechanical (3-point bending strength and Monnin hardness) and physical (bulk density and water absorption) characterization analyses. The results show that flexural strength increases from 27.56 MPa to 33.30 MPa for proportions ranging from 20% to 35% plastic content. Above 35% plastic, the strength drops to 19.60 MPa for a 50% plastic content. Similarly, the Monnin hardness drops from 9 mm to 5 mm when the plastic content varies from 20 to 50%. As for the results of the physical characterisation, the values obtained for apparent density vary from 0.89 to 1 for proportions varying from 20% to 35% plastic content and drop to 0.94 for 50% plastic content. As for water absorption, values drop from 6.82% to 2.45% when the plastic content increases from 20% to 50%. These mechanical strengths stabilise at 35% plastic content. The development of an 8/6 chevron composite material based on plastic and coconut shell could therefore be a way of recovering waste and solving the problem of deforestation.展开更多
Deep oil and gas reservoirs are under high-temperature conditions,but traditional coring methods do not consider temperature-preserved measures and ignore the influence of temperature on rock porosity and permeability...Deep oil and gas reservoirs are under high-temperature conditions,but traditional coring methods do not consider temperature-preserved measures and ignore the influence of temperature on rock porosity and permeability,resulting in distorted resource assessments.The development of in situ temperaturepreserved coring(ITP-Coring)technology for deep reservoir rock is urgent,and thermal insulation materials are key.Therefore,hollow glass microsphere/epoxy resin thermal insulation materials(HGM/EP materials)were proposed as thermal insulation materials.The materials properties under coupled hightemperature and high-pressure(HTHP)conditions were tested.The results indicated that high pressures led to HGM destruction and that the materials water absorption significantly increased;additionally,increasing temperature accelerated the process.High temperatures directly caused the thermal conductivity of the materials to increase;additionally,the thermal conduction and convection of water caused by high pressures led to an exponential increase in the thermal conductivity.High temperatures weakened the matrix,and high pressures destroyed the HGM,which resulted in a decrease in the tensile mechanical properties of the materials.The materials entered the high elastic state at 150℃,and the mechanical properties were weakened more obviously,while the pressure led to a significant effect when the water absorption was above 10%.Meanwhile,the tensile strength/strain were 13.62 MPa/1.3%and 6.09 MPa/0.86%at 100℃ and 100 MPa,respectively,which meet the application requirements of the self-designed coring device.Finally,K46-f40 and K46-f50 HGM/EP materials were proven to be suitable for ITP-Coring under coupled conditions below 100℃ and 100 MPa.To further improve the materials properties,the interface layer and EP matrix should be optimized.The results can provide references for the optimization and engineering application of materials and thus technical support for deep oil and gas resource development.展开更多
We investigated the hydration behavior and some physical/mechanical properties of cement-bonded particleboard （CBPB） containing particles of wheat straw and poplar wood at various usage ratios and bonded with Portla...We investigated the hydration behavior and some physical/mechanical properties of cement-bonded particleboard （CBPB） containing particles of wheat straw and poplar wood at various usage ratios and bonded with Portland cement mixed with different levels of inorganic additives. We determined the setting time and compression strength of cement pastes containing different additives and particles, and studied the effects of these additives and particles on thickness swelling, internal bond strength and modulus of rupture of CBPB by using RSM （Response Surface Methodology）. The mathematical model equations （second-order response functions） were derived to optimize properties of CBPB by computer simulation programming. Predicted values were in agreement with experimental values （R2 values of 0.93, 0.96 and 0.96 for TS, IB and MOR, respectively）. RSM can be efficiently applied to model panel properties. The variables can affect the properties of panels. The cement composites with bending strength 〉 12.5 MPa and internal bond strength 〉 0.28 MPa can be made by using wheat straw as a reinforcing material. Straw particle usage up to 11.5% in the mixture satisfies the minimum requirements of International Standard, EN 312 （2003） for IB and MOR. The dose of 4.95% calcium chloride, by weight of cement, can improve mechanical properties of the panels at the minimum requirement of EN 312. By increasing straw content from 0 to 30%, TS was reduced by increasing straw particle usage up to 1.5% and with 5.54% calcium chloride in the mixture, TS satisfied the EN 312 standard.展开更多
Eight complexes of rare earth with 2 mercaptobenthiazole, RELCl 2·RE(OH) 3· x H 2O (L=2 mercaptobenthiazole, RE= La～Gd, Y, except for Pm, x =0, 2～4), were synthesized in unhydrous ethanol and char...Eight complexes of rare earth with 2 mercaptobenthiazole, RELCl 2·RE(OH) 3· x H 2O (L=2 mercaptobenthiazole, RE= La～Gd, Y, except for Pm, x =0, 2～4), were synthesized in unhydrous ethanol and characterized by elemental analyses, IR spectra and thermal analyses. The results show that the ligand is coordinated to the RE ion through both the exocyclic sulfur and the thiazole nitrogen. The vulcanizing properties of the La complex as accelerator were studied in the traditional tire rubber, which indicate that the cross linked rubber accelerated by the rare earth complex has good physical and dynamic mechanical properties by comparison.展开更多
Under the condition of freeze-thaw cycles, two types of rocks （granite and andesite）, used as slope protection for the Qinghai-Tibet Railway, were tested according to the special climatic conditions in the Tibetan P...Under the condition of freeze-thaw cycles, two types of rocks （granite and andesite）, used as slope protection for the Qinghai-Tibet Railway, were tested according to the special climatic conditions in the Tibetan Plateau, and their various damage processes in ap- pearance were carefully observed. Observation results show that damage of andesite was more serious than that of granite. Using an acoustic instrument, ultrasonic velocity was tested. The changing trends of velocity with the number of freeze-thaw cycles were analyzed, and the freeze-thaw cycle damaging the physical and mechanical properties of rocks can be seen. According to the changing trends of ultrasonic velocity with the number of freeze-thaw cycles, mechanical parameters of rocks, such as dynamic elasticity modulus, Poisson＇s ratio, and dynamic bulk modulus were analyzed. It is found that they all have declining trends as the number of fi＇eeze-thaw cycles increases, and in particular, when the cycle number reaches a certain extent, the Poisson＇s ratio of rocks begins to become negative.展开更多
In China,especially in Xinjiang Region,mulch film remaining in the soil has severely jeopardized the safety of soil resources.To numerically simulate the residual film-soil-recovery implementation system,a virtual mul...In China,especially in Xinjiang Region,mulch film remaining in the soil has severely jeopardized the safety of soil resources.To numerically simulate the residual film-soil-recovery implementation system,a virtual mulch film model with consistent physical and mechanical properties with real mulch film needs to be established.In this study,a flexible deformable virtual mulch film model was constructed using YADE software based on the Minkowski Sum principle and the ball-ball force-displacement constitutive rule,as well as the contact failure rule were established.The deformation behaviors of cylinders and PFacet elements,such as stretching,bending,and torsion,were described.By splicing the basic PFacet elements,a virtual mulch model was established.The mechanical model of a virtual mulch film under tension was established and the axial tensile stiffness coefficient kn was determined to be 43.30 N·m.To verify the physical and mechanical properties of this virtual mulch film,both real and virtual stretching and tearing tests were conducted.The experimental results showed that:in the process of stretching and tearing of real and virtual films,the properties of morphological features of both are basically identical;however,they clearly differ in force-displacement.The viscoelastic constitutive model between balls and yield judgment conditions requires further study.展开更多
For manufacturing low-formaldehyde emission particleboard from wheat straw and urea-formaldehyde （UF） resins using urea treatment for indoor environments, we investigated the influence of urea treatment on the forma...For manufacturing low-formaldehyde emission particleboard from wheat straw and urea-formaldehyde （UF） resins using urea treatment for indoor environments, we investigated the influence of urea treatment on the formaldehyde emission, physical and mechanical properties of the manufactured particleboard. Wheat straws were treated at three levels of urea concentration （5%, 10%, 15%） and 95℃ as holding temperature. Wheat straw particleboards were manufactured using hot press at 180℃ and 3 MPa with two types of UF adhesive （UF-45, UF-91）. Then the formaldehyde emission values, physical properties and mechanical properties were considered. The results show that the for- maldehyde emission value was decreased by increasing urea concentration. Furthermore, the results indicate that the specimens under urea treatment have better mechanical and physical properties compared with control specimens. Also specimens under urea treatment at 10% concentration and UF-91 type adhesive have the most optimum physical and mechanical strength.展开更多
文摘The use of soil as a construction material is limited due to climatic conditions such as rain and wind effects. The valorization of industrial and agricultural by-products in soil-material-based composites for construction materials is an alternative to producing eco-materials for building construction. This study evaluates the effect of Shea Butter residue (SBr) and hydrated lime (HL) as stabilizers on the performance of Compressed Earth Blocks (CEB). For the production of CEB specimens, firstly the dry mixtures were prepared using soil material and 5 wt% HL, 5% - 25% wt% SBr and secondly, the appropriate amount of water was thoroughly mixed with the dry mixtures using the result of the proctor compaction test. All the moistened mixtures were mechanically pressed into CEBs on mold size (29.5 cm × 14 cm × 9.5 cm), cured at ambient temperature in the lab for 0 - 45 days, and dried at 60˚C for 7 days before being tested. The results give for the accessible porosity, bulk density, maximum dry and wet compressive strength, the respective value 31.58%;1580 kg/cm2;3.26 MPa and 0.75 MPa for CEB stabilized with 5 wt% lime without SBr. Moreover, the abrasion coefficient (14.49 cm2/g), the mass lost (0.08%), the surface depth (3.25 mm/h), the eroded surface (9.12 cm2), the sorptivity (0.046 g/cm2·min1/2 the absorption by total immersion at 2 h and 24 h (4.06 and 11.94%) are best for the CEBs stabilized with 5/5 wt% HL/SSBr. However, the lower thermal properties were obtained with CEB stabilized with 25 wt% SSBr. We therefore observe the significant reaction between these industrial and agricultural by-products with the earth material, with effects particularly on the hydric, thermal and durability properties. The use of industrial and agricultural by-products such as lime and SBr at an appropriate rate of 5 wt% are suitable to improve CEBs performances.
文摘Coral sand is a unique material developed in the tropical ocean environment, which is mainly composed of coral and other marine organism debris, with the CaCO3 content up to 96 %. It has special physical and mechanical properties due to its composition, structure and sedimentary environment. In this contribution, we discuss its specific gravity, porosity ratio compressibility, crushing, shearing and intensity for coral sand samples from the Nansha islands based on laboratory mechanical tests. Our results show distinct high porosity ratio, high friction angle and low intensity as compared with the quartz sand. We believe that grain crushing is the main factor that influences the deformation and strength of coral sand. Comprehensive study on the physical and mechanical properties of coral sands is significant in providing reliable scientific parameters to construction on coral islet, and thus avoids accidents in construction.
基金conducted as a joint research projectfinanced by SRTTU(Iran)UPM(Malaysia)
文摘We studied the effects of nanoparticles of organo-silane（NOS） compounds in the size range of20–80 nm on physical and mechanical properties in medium density fiberboard,and used NOS at four consumption levels of 0,50,100,and 150 g kg-1dry wood fibers.Density of all treatments was kept constant at 0.67 g cm-3.The water-repellent property of organo-silane significantly reduced water absorption（WA） and thickness swelling but mechanical properties declined due to the reduced proportion of wood-fiber as organo-silane was added to the matrix：the compression ratio of MDF panels and the integrity among wood-fibers both declined,resulting in reduced mechanical properties.We recommend use of 50 g of NOS/kg wood-fiber to improve WA and thickness swelling while retaining acceptable mechanical properties.
基金The National Natural Science Foundation of China,Grant/Award Number:41702326the Innovative Experts,Long-term Program of Jiangxi Province,Grant/Award Number:jxsq2018106049+1 种基金the Natural Science Foundation of Jiangxi Province,Grant/Award Number:20202ACB214006the Supported by Program of Qingjiang Excellent Young Talents,Jiangxi University of Science and Technology。
文摘In deep-earth engineering,the high earth temperature can significantly affect the rock's mechanical properties,especially when the rock is cooled during the construction process.Accordingly,whether the cooling speed affects the mechanical and physical properties of rocks is worth to be investigated.The present study explored the influence of the cooling rate on the physical and chemical properties of granite heated at 25–800°C.The mechanical and physical properties involved in this study included uniaxial compression strength,peak strain,modulus,P-wave velocity,mass and volume,the change of which could reflect the sensitivity of granite to the cooling rate.Acoustic emission(AE)monitoring,microscopic observation,and X-ray diffraction(XRD)are used to analyze the underlying damage mechanism.It is found that more AE signals and large-scale cracks are accounted for based on the b-value method when the specimens are cooled by water.Furthermore,the microscopic observation by polarized light microscopy indicates that the density,opening degree,and connectivity of the cracks under water cooling mode are higher than that under natural cooling mode.In addition,the XRD illustrates that there is no obvious change in mineral content and diffraction angle at different temperatures,which confirms that the change of mechanical properties is not related to the chemical properties.The present conclusion can provide a perspective to assess the damage caused by different cooling methods to hot rocks.
文摘The objective of this investigation was to introduce a cement-based composite of higher quality. For this purpose new hybrid nanocomposite from bagasse fiber,glass fiber and multi-wall carbon nanotubes（MWCNTs）were manufactured. The physical and mechanical properties of the manufactured composites were measured according to standard methods. The properties of the manufactured hybrid nanocomposites were dramatically better than traditional composites. Also all the reinforced composites with carbon nanotube, glass fiber or bagasse fiber exhibited better properties rather than neat cement.The results indicated that bagasse fiber proved suitable for substitution of glass fiber as a reinforcing agent in the cement composites. The hybrid nanocomposite containing10 % glass fiber, 10 % bagasse fiber and 1.5 % MWCNTs was selected as the best compound.
基金the Postgraduate Scientific Research Innovation Project of Hunan Province(No.CX20210867)the Scientific Innovation Fund for Postgraduates of Central South University of Forestry and Technology(No.CX202102030).
文摘The artificial afforestation of precious Phoebe bournei has been carried out in China.During the cultivation process,thinning wood will be produced.The properties of thinning wood might vary greatly with matured wood and require evaluation for better utilization.The objective of the present study aims to determine the wood structure,fiber morphology,and physical and mechanical properties of the Phoebe bournei thinning wood to help us understand the wood properties and improve its utility value.Three 14-year-old Phoebe bournei were cut from Jindong Forestry Farm of Hunan Province,China.The wood structure and fiber morphology were observed and analyzed with a light microscope and scanning electron microscope.The physical and mechanical properties were tested according to the Chinese national standards.The results showed as follows:(1)The Phoebe bournei thinning wood has a beautiful wood figure and fine texture,whereas the heartwood has not yet formed.(2)It is a diffuse-porous hardwood with small and less pores as well as fine wood rays.(3)The wood fiber is medium length and extremely thin wall thickness.(4)It is low in density and has excellent dimensionally stability.(5)The wood mechanical properties belong to the low to medium class and the comprehensive strength of wood belongs to the medium-strength class.It is concluded that Phoebe bournei thinning wood is suitable for wood carving,handicraft,high-end furniture,and decorative furniture parts.
文摘The use of agricultural waste in construction is an advantage favorable to environmental sanitation, the preservation of non-renewable resources but also to the execution of an ecological work. The objective of this work is to study the influence of the addition of palm nut cockles ash as an adjuvant on the physico-mechanical properties of concrete. For this study, ordinary concretes and ash concretes were made and subjected to physical and mechanical characterization tests at different maturation periods. The results of the tests carried out indicate that the presence of ash reduces the workability and porosity of the concrete and then increases the density of the concrete to 6.3%. In addition, we found that incorporating the ash improves the mechanical strength of the concrete compared to the control concrete. Thus, the compressive strength of ash concrete is 32.07 MPa and that of splitting is 2.76 MPa at 28 days, which is satisfactory vis-à-vis the threshold of construction projects for ready concrete for use, which recommends a minimum of 25 MPa (compression) and 2.6 MPa (splitting) at 28 days. This improvement in mechanical performance can be attributed to the pozzolanic effect of the constituents of the ash. Therefore, the ash from palm nut shells can be used to improve the mechanical properties of concrete.
文摘In this paper, the physical and mechanical properties of laminated bamboo lumber were studied by testing moisture content, delamination ratio, horizontal shear strength, MOE and MOR of the structure-use material, in the same time, these subjects of finger-joint were tested too. The results showed that, the horizontal shear strength, MOR, MOE of laminated bamboo were superior to the ordinary structure-use timber in architecture, such as Pinus. The performance of aging test was not extraordinary, although the physical and mechanical properties of laminated bamboo lumber decreased after aging test, these properties were beyond Pinus yet.
文摘This experimental study assesses the effectiveness of traditional and nano-materials in enhancing the physical and mechanical properties of deteriorated sandstone from Ramesses III Temple, Karnak, Luxor, Egypt. Treatments included Nano Estel (5%), Paraloid B-72 (3%), Paraloid B-72/Nano Estel (3%/5%), and ethyl silicates. Treated samples underwent Scanning Electron Microscopy (SEM) and physical/mechanical testing. Results show that Paraloid B-72/Nano Estel (3%/5%) yielded optimal consolidation, significantly improving sandstone’s physical and mechanical properties.
文摘With growing concerns for global warming and environmental issues,the research community has contributed significantly to green technology in the area of material science through the development of natural fiber-reinforced polymer composites(NFRPC).Polymers serve as the matrix in NFRPC,while natural fibers serve as the reinforcing materials.Demand for high-performing materials made with natural resources is growing continuously.Natural fiber-reinforced polymer composites are sustainable biocomposites fabricated with natural fibers embedded with a polymer matrix.They offer a wide range of advantages,including a low weight-to-strength ratio,high flexural strength,damping properties,and resistance to corrosion,wear,and impact.Understanding the basic properties,characteristics,and processing techniques for natural fibers is important to consider their use as raw materials for high-quality biocomposite.Natural fibers come with low density and a high strengthto-weight ratio,allowing them to be a potential reinforcement for low-weight composites.This article attempts to present a comprehensive review of the available natural fibers,their classification,types,structures,physical properties,characteristics,and mechanical properties.Natural fibers are hydrophilic in nature and require physical and chemical treatment prior to their application as reinforcing material.This review will also cover the required physical and chemical treatments of natural fibers for fabricating biocomposites.
基金the Fundamental Research Funds for the Central Universities(Project No.2022CDJKYJH037)the National Key R&D Program of China(Grant No.2021YFB3901402)。
文摘To study the damage mechanisms of anhydrite rock under freeze-thaw cycles, the physicalmechanical properties and the microcracking activities of anhydrite rock were investigated through mass variation, nuclear magnetic resonance, scanning electron microscope tests, and uniaxial compression combined with acoustic emission(AE) tests. Results show that with the increase of freeze-thaw processes,the mass, uniaxial compression strength, and elastic modulus of the anhydrite specimens decrease while the porosity and plasticity characteristics increase.For example, after 120 cycles, the uniaxial compression strength and elastic modulus decrease by 46.54% and 60.16%, and the porosity increase by 75%. Combined with the evolution trend of stressstrain curves and the detected events, three stages were labeled to investigate the AE characteristics in freeze-thaw weathered anhydrite rock. It is found that with the increase of freeze-thaw cycles, the proportions of AE counts in stage Ⅰ and stage Ⅱ show a decaying exponential trend. Contrarily, the proportion of AE counts in stage Ⅲ displays an exponential ascending trend. Meanwhile, as the freeze-thaw cycles increase, the low-frequency AE signals increase while the intermediate-frequency AE signals decrease. After 120 cycles, the proportion of low-frequency AE signals increases by 168.95%, and the proportion of intermediate-frequency AE signals reduces by 81.14%. It is concluded that the microtensile cracking events occupy a dominant position during the loading process. With the increase of freeze-thaw cycles, the b value of samples decreases.After 120 cycles, b value decreases by 27.2%, which means that the proportion of cracking events in rocks with small amplitude decreases. Finally, it is proposed that the freeze-thaw damage mechanism of anhydrite is also characterized by the water chemical softening effect.
文摘Research into the fundamental properties of microcapsules and use of the results to develop a wide variety of products in industries such as printing, fast-moving consumer goods, construction, pharmaceuticals, and agrochemicals is a dynamic and ever-progressing field of study. For microcapsules to be effective in providing protection from harsh environments or delivering large payloads, it is essential to have a good understanding of their properties to enable quality control during formulation, storage, and applications. This review aims to outline the commonly used techniques for determining the physicochemical, struc- tural, and mechanical properties of microcapsules, and highlights the interlinked nature of these three areas with respect to the end-use industrial application. This review provides information on techniques that are well supported in the literature, and also examines microcapsule analytical techniques that will become more prevalent as a result of new technological developments or extensions from other areas of study.
文摘This study assesses the reactivity of four (04) different types of clayey earthen materials (Kamboinsé, Pabré, Saaba, and Kossodo) with Ca(OH)<sub>2</sub>, analytical lime (AL) versus lime residu (LR), in ambient conditions. The effect of the stabilization of the earth with the LR was also studied on the performances of compressed earth blocks (CEB). The lime content varied from 0% to 20% with respect to the mass of dry earth material. The analysis of the reactivity and physico-mechanical properties were respectively carried out on the solutions of the mixtures (earth + LR and earth + AL) and CEB (earth + LR). The mixtures were cured between 0 and 60 days at the ambient temperature of laboratory (30<span style="white-space:nowrap;">℃</span> ± 5<span style="white-space:nowrap;">℃</span>). The results showed that the reactivity of the clayey earth materials with AL is comparable to that with the LR. At the same time, this reactivity improved the physical and mechanical properties of stabilized CEB depending on the type of earth material, lime content and curing time. The maximum values of the dry compressive strength, observed for each material stabilized with 20% LR, are 6 and 7 MPa (Kamboinsé), 8.8 and 9.3 MPa (Pabré), 6 and 6.5 MPa (Saaba), 8.8 and 9.7 MPa (Kossodo) respectively at curing time of 28 and 45 days. The structural efficiency of CEB was also improved which implies that, in the current conditions, the stabilization of earth materials using LR allows to produce the CEB for potential applications in wall masonry.
文摘In this paper, the authors aim to propose the use of waste plastics as a binder in a coconut shell reinforcement for the development of an 8/6 size composite rafter to replace the natural 8/6 size backbone in construction. Following a study into the choice of the best proportions, a total of 30 size 8/6 composite rafters with different proportions of 20%, 25%, 30%, 35%, 40% and 50% plastic content were developed. All the 8/6 composite rafters were subjected to mechanical (3-point bending strength and Monnin hardness) and physical (bulk density and water absorption) characterization analyses. The results show that flexural strength increases from 27.56 MPa to 33.30 MPa for proportions ranging from 20% to 35% plastic content. Above 35% plastic, the strength drops to 19.60 MPa for a 50% plastic content. Similarly, the Monnin hardness drops from 9 mm to 5 mm when the plastic content varies from 20 to 50%. As for the results of the physical characterisation, the values obtained for apparent density vary from 0.89 to 1 for proportions varying from 20% to 35% plastic content and drop to 0.94 for 50% plastic content. As for water absorption, values drop from 6.82% to 2.45% when the plastic content increases from 20% to 50%. These mechanical strengths stabilise at 35% plastic content. The development of an 8/6 chevron composite material based on plastic and coconut shell could therefore be a way of recovering waste and solving the problem of deforestation.
基金supported by the Sichuan Science and Technology Program (Grant Nos.2023NSFSC0004,2023NSFSC0790)the National Natural Science Foundation of China (Grant Nos.51827901,52304033)the Sichuan University Postdoctoral Fund (Grant No.2024SCU12093)。
文摘Deep oil and gas reservoirs are under high-temperature conditions,but traditional coring methods do not consider temperature-preserved measures and ignore the influence of temperature on rock porosity and permeability,resulting in distorted resource assessments.The development of in situ temperaturepreserved coring(ITP-Coring)technology for deep reservoir rock is urgent,and thermal insulation materials are key.Therefore,hollow glass microsphere/epoxy resin thermal insulation materials(HGM/EP materials)were proposed as thermal insulation materials.The materials properties under coupled hightemperature and high-pressure(HTHP)conditions were tested.The results indicated that high pressures led to HGM destruction and that the materials water absorption significantly increased;additionally,increasing temperature accelerated the process.High temperatures directly caused the thermal conductivity of the materials to increase;additionally,the thermal conduction and convection of water caused by high pressures led to an exponential increase in the thermal conductivity.High temperatures weakened the matrix,and high pressures destroyed the HGM,which resulted in a decrease in the tensile mechanical properties of the materials.The materials entered the high elastic state at 150℃,and the mechanical properties were weakened more obviously,while the pressure led to a significant effect when the water absorption was above 10%.Meanwhile,the tensile strength/strain were 13.62 MPa/1.3%and 6.09 MPa/0.86%at 100℃ and 100 MPa,respectively,which meet the application requirements of the self-designed coring device.Finally,K46-f40 and K46-f50 HGM/EP materials were proven to be suitable for ITP-Coring under coupled conditions below 100℃ and 100 MPa.To further improve the materials properties,the interface layer and EP matrix should be optimized.The results can provide references for the optimization and engineering application of materials and thus technical support for deep oil and gas resource development.
基金supported by Department of Wood and Paper Science and Technology,University of Zabol
文摘We investigated the hydration behavior and some physical/mechanical properties of cement-bonded particleboard （CBPB） containing particles of wheat straw and poplar wood at various usage ratios and bonded with Portland cement mixed with different levels of inorganic additives. We determined the setting time and compression strength of cement pastes containing different additives and particles, and studied the effects of these additives and particles on thickness swelling, internal bond strength and modulus of rupture of CBPB by using RSM （Response Surface Methodology）. The mathematical model equations （second-order response functions） were derived to optimize properties of CBPB by computer simulation programming. Predicted values were in agreement with experimental values （R2 values of 0.93, 0.96 and 0.96 for TS, IB and MOR, respectively）. RSM can be efficiently applied to model panel properties. The variables can affect the properties of panels. The cement composites with bending strength 〉 12.5 MPa and internal bond strength 〉 0.28 MPa can be made by using wheat straw as a reinforcing material. Straw particle usage up to 11.5% in the mixture satisfies the minimum requirements of International Standard, EN 312 （2003） for IB and MOR. The dose of 4.95% calcium chloride, by weight of cement, can improve mechanical properties of the panels at the minimum requirement of EN 312. By increasing straw content from 0 to 30%, TS was reduced by increasing straw particle usage up to 1.5% and with 5.54% calcium chloride in the mixture, TS satisfied the EN 312 standard.
文摘Eight complexes of rare earth with 2 mercaptobenthiazole, RELCl 2·RE(OH) 3· x H 2O (L=2 mercaptobenthiazole, RE= La～Gd, Y, except for Pm, x =0, 2～4), were synthesized in unhydrous ethanol and characterized by elemental analyses, IR spectra and thermal analyses. The results show that the ligand is coordinated to the RE ion through both the exocyclic sulfur and the thiazole nitrogen. The vulcanizing properties of the La complex as accelerator were studied in the traditional tire rubber, which indicate that the cross linked rubber accelerated by the rare earth complex has good physical and dynamic mechanical properties by comparison.
基金supported in part by the Important Orientation Projects of the CAS (KZCX2-YW-Q03-04)the Grant of the Western Project Program of the Chinese Academy of Sciences (KZCX2-XB2-10)Natural Science Foundation of China (Grant No. 40625004,40821001)
文摘Under the condition of freeze-thaw cycles, two types of rocks （granite and andesite）, used as slope protection for the Qinghai-Tibet Railway, were tested according to the special climatic conditions in the Tibetan Plateau, and their various damage processes in ap- pearance were carefully observed. Observation results show that damage of andesite was more serious than that of granite. Using an acoustic instrument, ultrasonic velocity was tested. The changing trends of velocity with the number of freeze-thaw cycles were analyzed, and the freeze-thaw cycle damaging the physical and mechanical properties of rocks can be seen. According to the changing trends of ultrasonic velocity with the number of freeze-thaw cycles, mechanical parameters of rocks, such as dynamic elasticity modulus, Poisson＇s ratio, and dynamic bulk modulus were analyzed. It is found that they all have declining trends as the number of fi＇eeze-thaw cycles increases, and in particular, when the cycle number reaches a certain extent, the Poisson＇s ratio of rocks begins to become negative.
基金This work was financially supported by the Xinjiang Production and Construction Corps Major Technology Project(2018AA001/03)the China 13th Five-Year Key Research and Development Plan(2017YFD0701102-1)+1 种基金the Corps Key R&D Projects(2019AB007)the China National Natural Science Foundation Project(11562019).
文摘In China,especially in Xinjiang Region,mulch film remaining in the soil has severely jeopardized the safety of soil resources.To numerically simulate the residual film-soil-recovery implementation system,a virtual mulch film model with consistent physical and mechanical properties with real mulch film needs to be established.In this study,a flexible deformable virtual mulch film model was constructed using YADE software based on the Minkowski Sum principle and the ball-ball force-displacement constitutive rule,as well as the contact failure rule were established.The deformation behaviors of cylinders and PFacet elements,such as stretching,bending,and torsion,were described.By splicing the basic PFacet elements,a virtual mulch model was established.The mechanical model of a virtual mulch film under tension was established and the axial tensile stiffness coefficient kn was determined to be 43.30 N·m.To verify the physical and mechanical properties of this virtual mulch film,both real and virtual stretching and tearing tests were conducted.The experimental results showed that:in the process of stretching and tearing of real and virtual films,the properties of morphological features of both are basically identical;however,they clearly differ in force-displacement.The viscoelastic constitutive model between balls and yield judgment conditions requires further study.
文摘For manufacturing low-formaldehyde emission particleboard from wheat straw and urea-formaldehyde （UF） resins using urea treatment for indoor environments, we investigated the influence of urea treatment on the formaldehyde emission, physical and mechanical properties of the manufactured particleboard. Wheat straws were treated at three levels of urea concentration （5%, 10%, 15%） and 95℃ as holding temperature. Wheat straw particleboards were manufactured using hot press at 180℃ and 3 MPa with two types of UF adhesive （UF-45, UF-91）. Then the formaldehyde emission values, physical properties and mechanical properties were considered. The results show that the for- maldehyde emission value was decreased by increasing urea concentration. Furthermore, the results indicate that the specimens under urea treatment have better mechanical and physical properties compared with control specimens. Also specimens under urea treatment at 10% concentration and UF-91 type adhesive have the most optimum physical and mechanical strength.
