Possibility of making Al-Pb alloy plate with Pb dispersed uniformly by LDC (Liquid Dynamic Compact) technology has been studied in the present paper. The relationship among the distance between nozzle and cooled base ...Possibility of making Al-Pb alloy plate with Pb dispersed uniformly by LDC (Liquid Dynamic Compact) technology has been studied in the present paper. The relationship among the distance between nozzle and cooled base plate and the atomization pressure as well as the density of the Al-Pb alloy slab is measured. The relative density of the LDC Al-Pb alloy slab can reach 90% under condition of the present experiment. Microstructure of the slab consist of equal axial grains with 15 approximately 25 μm in diameter and Pb dispersed uniformly in them. After cold or hot rolling of the slab with reduction of 50 approximately 60%, the microstructure can be densified. The rolled Al-Pb alloy plate can be compacted together with pure Al plate very well.展开更多
The paper studies the probability of industrial application of vibration liquefaction of bulk solid from the opposite point of view, and proposing turning its harmful effects into benefits. Utilizing a new device of v...The paper studies the probability of industrial application of vibration liquefaction of bulk solid from the opposite point of view, and proposing turning its harmful effects into benefits. Utilizing a new device of vibration liquefaction and by compacting saturated bulk solid, a set of additional device for experiment was designed. These experiments examined the problems related to vibration liquefaction of fine ores and tailings on the basis of DSA 1 type direct shear apparatus, including models of straight tubes, curved tubes and a sandbox. The changing properties of tailings under vibration and the mechanism of vibration liquefaction and compacting of tailings were studied, and future application of the technique to mines has been put forward.展开更多
In the present scenario,computational modeling has gained much importance for the prediction of the properties of concrete.This paper depicts that how computational intelligence can be applied for the prediction of co...In the present scenario,computational modeling has gained much importance for the prediction of the properties of concrete.This paper depicts that how computational intelligence can be applied for the prediction of compressive strength of Self Compacting Concrete(SCC).Three models,namely,Extreme Learning Machine(ELM),Adaptive Neuro Fuzzy Inference System(ANFIS)and Multi Adaptive Regression Spline(MARS)have been employed in the present study for the prediction of compressive strength of self compacting concrete.The contents of cement(c),sand(s),coarse aggregate(a),fly ash(f),water/powder(w/p)ratio and superplasticizer(sp)dosage have been taken as inputs and 28 days compressive strength(fck)as output for ELM,ANFIS and MARS models.A relatively large set of data including 80 normalized data available in the literature has been taken for the study.A comparison is made between the results obtained from all the above-mentioned models and the model which provides best fit is established.The experimental results demonstrate that proposed models are robust for determination of compressive strength of self-compacting concrete.展开更多
This study examined the relationship between selected physico-mechanical properties, compacting pressure and mixing proportion of briquettes produced from combination of maize cob particles and sawdust of low, medium ...This study examined the relationship between selected physico-mechanical properties, compacting pressure and mixing proportion of briquettes produced from combination of maize cob particles and sawdust of low, medium and high density timber species. Particle sizes of maize cobs and sawdust used for the study were ≤1 mm. The two materials were combined at mixing percentages of 90:10, 70:30 and 50:50 (Sawdust:maize cobs). Briquettes were produced at room temperature (28°C) using compacting pressures 20, 30, 40 and 50 MPa. The results suggested that combining maize cob particles with sawdust of low, medium and high density wood species could significantly enhance the relaxed density, compressive strength in cleft and impact resistance index of briquettes produced from agricultural biomass residue like maize cobs. The results further indicated that the physical and mechanical characteristics of briquettes produced from combinations of sawdust of low density species and maize cobs were exceptionally higher than that produced from combinations of maize cob particles, and medium density and high density timber species. The R2 values for the regression model between the independent variables (mixing percentage and compacting pressure) and relaxed density, compressive strength in cleft and impact resistance index of briquettes produced from combinations of maize cob particles and sawdust of low density species (Ceiba pentandra) were 0.966, 0.932 and 0.710 respectively. This study provides a hope for briquetting maize cobs at room temperature using a low compacting pressure.展开更多
A short term field mesocosm experiment was performed in semi-deciduous forest areas of Ivory Coast to assess the impact of a decompacting （Hyperiodrilus africanus, Eudrilidae） and two compacting （Millsonia omodeoi ...A short term field mesocosm experiment was performed in semi-deciduous forest areas of Ivory Coast to assess the impact of a decompacting （Hyperiodrilus africanus, Eudrilidae） and two compacting （Millsonia omodeoi and Dichogaster terrae nigrae, Acanthodrilidae） earthworm species on soil properties. These species have been selected for their predominance in the re- gion and their contrasting impact on soil structure. The experimental design consisted of a treatment without worms （control）, and treatments with one, two or three species of earthworms. Both compacting and decompacting earthworms increased water infil- tration rate in all treatments, with marked impact in H. africanus and M. omodeoi＋D, terraenigrae treatments. Interactions be- tween compacting and decompacting species resulted in more large aggregates in comparison to when the compacting species D. terraenigrae was alone. This may be accounted for by their compacting attribute as compacting earthworms are responsible for producing the highest number of large aggregates. The low values of mean weight diameter in treatments combining decompact-ing and compacting earthworms compared with compacting ＂M. omodeoi＂ one also confirmed the trend of decline in soil com-paction in the presence of the decompacting species. These results showed positive impact of species richness on soil structure regulation, which is crucial in ecosystem productivity and support consequently the insurance hypothesis. In fact, this study showed that the preservation of earthworm species belonging to these two contrasting functional groups is essential for the main-tenance of stable soil structure regulation in agro-tropical ecosystems.展开更多
Most of the construction materials research now concerns on investigation of construction materials that is locally produced at a rate and cost compatible with the pace of construction. The present paper is concerned ...Most of the construction materials research now concerns on investigation of construction materials that is locally produced at a rate and cost compatible with the pace of construction. The present paper is concerned with investigation of fresh and hardened properties of self-compacting concrete (SCC) produced from local available materials in JORDAN. The produced SCC contains the local stone cut waste powder which is called Al-KHAMKHA in JORDAN with different replacement of (0%, 10%, and 25%) of fine silica aggregate;?the study also investigatesthe effects of SP33 super?plasticizer which is used by different doses (1%, 1.5% and 2%) for cement. The slump flow and the compressive strength of SCC were studied and the experimental results indicate the possibility of using Al-KHAMKHA in the production of SCC as the results showed that the compressive strength of the SCC with 10 % replacement by al-khamkha together with 1% SP33?super plasticizer was higher compared to pure SCC without al-khamkha;?the results also showed that as al-khamkha content increased the slump flow decreased.展开更多
The technology of concrete has significantly increased in recent years through the use of super plasticizer and availability of mineral additions. One of the most recent materials used as an additive, replacing a port...The technology of concrete has significantly increased in recent years through the use of super plasticizer and availability of mineral additions. One of the most recent materials used as an additive, replacing a portion of cement in concrete, is fine clay fired at a temperature of 800℃ to 900℃. This research is based on trials that complied with artificial pozzolan (waste crushed brick), and their effect on the rheological and mechanical behavior of mortar. The addition of 5% of a waste crushed brick has helped not only to improve the strength (tensile and compression), but also to foster a better rheological behavior in terms of fluidity and stability, with a low heat of hydration compared to control. However, tests of optimizing the content of self-compacting concrete (SCC) in coarse aggregates, sand and binder, led us to confirm that the combined mass of more optimal (better workability and stability) is that based on low in volumetric percentage of sand/paste with a granular skeleton richest gravel low dimensions (2/3 of G 3/8 and 1/3 of G 8/15).展开更多
This paper presents the results of experimental investigations on mechanical properties of self compacting concrete made with local materials. The used materials were cement, aggregate and super plasticizer. Limestone...This paper presents the results of experimental investigations on mechanical properties of self compacting concrete made with local materials. The used materials were cement, aggregate and super plasticizer. Limestone powder, silica fume and blast furnace slag have been used as adjuvant in self compacting concrete (SCC). Self compacting concrete properties in fresh and hardened state are characterized and analyzed. The test results indicate the possibility to manufacture SCC with good rheological and mechanical properties using local materials.展开更多
This study proposed a new way to formulate a low energy super-sulfated cement (SSC) which can be used to produce self-compacting concrete (SCC) with high compressive strength and durability in terms of chloride penetr...This study proposed a new way to formulate a low energy super-sulfated cement (SSC) which can be used to produce self-compacting concrete (SCC) with high compressive strength and durability in terms of chloride penetration resistance. This innovative SSC, different from the traditional SSC, was purely produced with a ternary mixture of three industrial by-products of ground granulated blast furnace slag, low calcium Class F fly ash and circulating fluidized bed combustion (CFBC) fly ash and was denoted as SFC-SSC (super-sulfated cement made by mixture of slag, Class F fly ash and CFBC fly ash). Experimental results showed that the combination of a fixed amount of 15 wt.% of CFBC fly ash with various ratios of Class F fly ash to slag could be used to produce the hardened SCCs with high 28-day compressive strengths (41.8 - 65.6 MPa). Addition of Class F fly ash led to the resulting SCCs with lowered price and preferable engineering properties, and thus it was considered as state-of-the-art method to drive such type of concrete towards sustainable construction materials.展开更多
Wood and fly ash were observed to have significant qualities that could improve the strength of self compacting concrete.The material was applied to increase the compressive strength of concrete strength.This material...Wood and fly ash were observed to have significant qualities that could improve the strength of self compacting concrete.The material was applied to increase the compressive strength of concrete strength.This material could be the demanding material for partial replacement for cement.The study observed the behaviour of the material from experts that applied these material through experimental investigation,but the study monitored the behaviour of this material by applied modeling and simulation to determine other effect that could influence the behaviour of these materials in compressive strength.This was to determine the significant effect on the addictive applied as partial replacement for cement.Lots of experts have done works on fly ash through experiment concept,but the application of predictive concept has not been carried out.The adoption of this concept has expressed other parameters that contributed to the efficiency of wood and fly ash as partial replacement for cement on self compacting concrete.The study adopting modeling and simulation observed 10 and 20%by weight of cement as it is reflected on its performance in the simulation,from the simulation wood recorded 10%as it was observed from the growth rate of this self compacting concrete reflected from the trend.The simulation for model validation was compared with the works of the studies carried out[20].And both values developed best fits correlation.展开更多
The engineering characteristics of weathered soft rock are important contents of soft rock mechanics. They also play a significant role in compacting deformation, which has been known to exert a significant amount of ...The engineering characteristics of weathered soft rock are important contents of soft rock mechanics. They also play a significant role in compacting deformation, which has been known to exert a significant amount of influence on the stability of highway filling subgrade engineering. In an effort to investigate this aspect of the problem, compacting tests and unconfined compressive strength tests have been carried out on weathered argillaceous slate and pelitic siltstone rocks, which are broken and graded before the test. The testing results indicate that the relationships of both between stress and strain and between axial strain and tangent modulus are exponential relationships; the size of the grain plays some influence on the deformation modulus, whereas the water content impacts the compressive strength greatly, which shows quadratic function; the unconfined compressive strength is linear with the dry density of loose soft rock mixtures. Therefore, the water content must be controlled in both the design and the construction of subgrade engineering of soft rock filling, and at the same time some effective measures should be taken to reach the requirement of compaction.展开更多
A new automatic rotary compactor and its abilities in compacting stone mastic asphalt （SMA） are presented. Following an overview of the rotary compactor and the compaction procedure, it is demonstrated that the rota...A new automatic rotary compactor and its abilities in compacting stone mastic asphalt （SMA） are presented. Following an overview of the rotary compactor and the compaction procedure, it is demonstrated that the rotary compactor is able to produce uniform slabs with the desired thickness of 65 mm all over around. Furthermore, 132 cored samples from the rotary compactor had been compacted uniformly with approximately 4% optimum air void content. In addition, performance tests results indicate that the rotary compactor produces asphalt mixturures with the requirements of resilient modulus, Marshall stability and flow. A weight factor was introduced for each fraction of aggregates in the degradation analysis to compensate the crushing effect of aggregates during mixing and compacting.展开更多
It is well known that the properties of material are determined by its structure and the interior atomic state. Nanosolid material is no exception either. Many unusual properties of nanosolid are indeed due to its par...It is well known that the properties of material are determined by its structure and the interior atomic state. Nanosolid material is no exception either. Many unusual properties of nanosolid are indeed due to its particular interfacial structuret. There are a large number of unsaturated coordination atoms located at the interface of nanosolids, and these atoms form a special interfacial structure with different types of bonds. As an展开更多
Parallel loops account for the greatest amount of parallelism in numerical programs.Executing nested loops in parallel with low run-time overhead is thus very important for achieving high performance in parallel proce...Parallel loops account for the greatest amount of parallelism in numerical programs.Executing nested loops in parallel with low run-time overhead is thus very important for achieving high performance in parallel processing systems.However,in parallel processing systems with caches or local memories in memory hierarchies,“thrashing problem”may arise when data move back and forth frequently between the caches or local memories in different processors.The techniques associated with parallel compiler to solve the problem are not completely developed.In this paper,we present two restructuring techniques called loop staggering,loop staggering and compacting,with which we can not only eliminate the cache or local memory thrashing phenomena significantly,but also exploit the potential parallelism existing in outer serial loop.Loop staggering benefits the dynamic loop scheduling strategies,whereas loop staggering and compacting is good for static loop scheduling strategies,Our method especially benefits parallel programs,in which a parallel loop is enclosed by a serial loop and array elements are repeatedly used in the different iterations of the parallel loop.展开更多
With increasing environmental pressure to reduce solid waste and to recycle as much as possible,the concrete industry has adopted a number of methods to achieve this goal by replacement of waste glass with concrete co...With increasing environmental pressure to reduce solid waste and to recycle as much as possible,the concrete industry has adopted a number of methods to achieve this goal by replacement of waste glass with concrete composition materials.Due to differences in mixture design,placement and consolidation techniques,the strength and durability of Self Compacting Concrete(SCC)may be different than those of conventional concrete.Therefore,replacement of waste glass with fine aggregate in SCC should deeply be investigated compared to conventional concretes.The aim of the present study is to investigate the effect of glass replacement with fine aggregate on the SCC properties.In present study,fine aggregate has been replaced with waste glass in six different weight ratios ranging from 0%to 50%.Fresh results indicate that the flow-ability characteristics have been increased as the waste glass incorporated to paste volume.Nevertheless,compressive,flexural and splitting strengths of concrete containing waste glass have been shown to decrease when the content of waste glass is increased.The strength reduction of concrete in different glass replacement ratios is not remarkable,thus it can be produced SCC with waste glass as fine aggregate in a standard manner.展开更多
In situ density and moisture content of asphalt pavement are essential controlling parameters that require accurate measurement for quality control and quality assurance purposes.The ground-penetrating radar(GPR)techn...In situ density and moisture content of asphalt pavement are essential controlling parameters that require accurate measurement for quality control and quality assurance purposes.The ground-penetrating radar(GPR)technique could provide non-destructive,non-contact,and full-coverage estimations of pavement density and moisture content.However,the technical readiness and drawbacks,including prediction models,signal processing algorithms,and testing hardware,remain unclear for agencies and construction practitioners,impeding large-scale implementations.This paper aims to provide a thorough review of the theoretical background and current practices of using GPR for non-destructive measurements of asphalt pavement density and moisture content during construction,thereby allowing for real-time correction of over-or under-compaction on site.The principles and applications of GPR-based density and moisture content prediction models were comprehensively summarized.Their strengths and limitations were discussed.Cutting-edge GPR equipment suitable for such applications was introduced,including their system components,application scenarios,and inherent limitations.Factors affecting prediction accuracy were analyzed.Advanced signal processing algorithms were discussed in the end,along with the in-place calibration procedure for aggregate dielectric constants.The reviewed technique could be a guiding tool for real-time monitoring of asphalt pavement density and moisture content using GPR,offering practical insights for future development and standardized deployment in construction quality management.展开更多
Soil compaction often imposes stress on root development and plant survival.However,root anatomical responses that enable persistent root growth and functioning under soil compaction remain unclear.We grew 10 herbaceo...Soil compaction often imposes stress on root development and plant survival.However,root anatomical responses that enable persistent root growth and functioning under soil compaction remain unclear.We grew 10 herbaceous species differing substantially in lateral root diameter,in soils with low(1.0 g cm^(-3))and high(1.4 g cm^(-3))bulk density,and assessed root traits including root biomass,anatomical structures,and respiration rates.Greater root thickening upon soil compaction was found in species with thicker first-order lateral roots,mainly due to larger cortical cell size.Both xylem vessel diameter and wall thickness increased more in compacted soils in these species.Despite these anatomical shifts,root respiration rate responded little to soil compaction across most species,likely due to the opposite investment in cortical cells and xylem vessels.Notably,root biomass,independent of root respiration rate and anatomical structures,determined whole-plant growth under soil compaction.Our study reveals two independent strategies of root response to soil compaction:anatomical remodeling for mechanical and metabolic maintenance,and root biomass investment for resource acquisition.These findings offer new insights for breeding and selecting species tolerant to soil compaction and highlight multidimensional strategies of plant adaptation to physical stress.展开更多
This paper represents experimental work on the mechanical and durability parameters of self-compacting concrete(SCC)with copper slag(CS)and fly ash(FA).In the first phase of the experiment,certain SCC mixes are prepar...This paper represents experimental work on the mechanical and durability parameters of self-compacting concrete(SCC)with copper slag(CS)and fly ash(FA).In the first phase of the experiment,certain SCC mixes are prepared with six percentages of FA replacing the cement ranging from 5%to 30%.In the second phase,copper slag replaces fine aggregate at an interval of 20%to 100%by taking the optimum percentage value of FA.The performance of SCC mixes containing FA and copper slag is measured with fresh properties,compressive,split tensile and flexural strengths.SCC durability metrics,such as resistance against chloride and voids in the concrete matrix,is measured with rapid chloride ion penetration test(RCPT)and sorptivity techniques.The microstructure of the SCC is analyzed by using SEM and various phases available in the concrete matrix identified with XRD analysis.It is found that when replacing cement with 20%of FA and replacing fine aggregate with 40%of copper slag in SCC,higher mechanical strengths will be delivered.Resistance of chloride and voids in the concrete matrix reaches the optimum value at 40%;and with the increase of dosage,the quality of SCC will be improved.Therefore,it is recommended that copper slag be used as a sustainable material for replacement of fine aggregate.展开更多
Ground penetrating radar(GPR)offers a rapid and non-destructive approach to evaluating asphalt mixtures by capturing variations in their dielectric constant.As a critical electromagnetic parameter,the dielectric const...Ground penetrating radar(GPR)offers a rapid and non-destructive approach to evaluating asphalt mixtures by capturing variations in their dielectric constant.As a critical electromagnetic parameter,the dielectric constant demonstrates significant potential for assessing the material composition and mechanical properties of asphalt mixtures.However,the relationship between the dielectric constant and mechanical properties remains unclear.To investigate the factors affecting the dielectric constant and its correlation with the mechanical properties of asphalt mixtures,a systematic analysis of the influencing parameters was conducted.Fitting equations were established to quantify the relationships between the dielectric constant and mechanical properties.Firstly,the effects of compaction state,testing frequency,and testing temperature on the dielectric constant were evaluated.Subsequently,forward simulations of GPR were executed on asphalt pavements with diverse air voids and detection frequencies.Finally,a fitting analysis was performed to determine the correlation between the dielectric constant and the dynamic modulus,compressive strength,and splitting tensile strength.The results indicated that the dielectric constant increased with the compaction state,decreased with increasing testing frequency until stabilized,and was insignificantly affected by changes in testing temperature.The change of air void in asphalt pavement has significantly affected the amplitude and timing of electromagnetic wave reflection.A linear positive correlation was identified between the dielectric constant and dynamic modulus as well as compressive strength,while a quadratic positive correlation existed with splitting tensile strength.This study provided theoretical and practical foundations for enhancing the reliability and accuracy of non-destructive testing in asphalt pavement.展开更多
Quantitative detection of sleeve grouting compactness is a technical challenge in civil engineering testing.This study explores a novel quantitative detection method based on ultrasonic time-frequency dual-domain anal...Quantitative detection of sleeve grouting compactness is a technical challenge in civil engineering testing.This study explores a novel quantitative detection method based on ultrasonic time-frequency dual-domain analysis.It establishes a mapping relationship between sleeve grouting compactness and characteristic parameters.First,this study made samples with gradient defects for two types of grouting sleeves,G18 and G20.These included four cases:2D,4D,6D defects(where D is the diameter of the grouting sleeve),and no-defect.Then,an ultrasonic input/output data acquisition system was established.Three-dimensional sound field distribution data were obtained through an orthogonal detection layout and pulse reflection principles.Finally,a novel quantification detection with a comprehensive defect index(DI)was established by comprehensively considering eight feature parameters,such as time-frequency domain Kurtosis factor(KU),Skewness factor(SK),Formfactor(FF),Crest factor(CF),Impulse factor(IF),Clearance factor(CLF),Wavelet packet energy entropy(WPEE),and Hilbert energy peak(HEP).Construct a DI index by quantifying the difference between defect signals and defect free signals in the time-frequency domain.Experimental results show that,under no-defect conditions,the values of feature parameters are significantly lower than those under defect conditions.Among these,the KU,FF,CF,WPEE and HEP exhibit strong correlations with grout sleeve compactness.The proposed DI index in both types of grout sleeves showed good universality with a linear fit goodness of 0.847–0.962.However,G20 the larger inner diameter and length of the sleeve result in a more complex medium effect during ultrasonic propagation,making its DI index more sensitive to defects than the G18 sleeve.Therefore,the presented method is effective for quantitative detection and analysis of the compactness of grouting sleeves.展开更多
文摘Possibility of making Al-Pb alloy plate with Pb dispersed uniformly by LDC (Liquid Dynamic Compact) technology has been studied in the present paper. The relationship among the distance between nozzle and cooled base plate and the atomization pressure as well as the density of the Al-Pb alloy slab is measured. The relative density of the LDC Al-Pb alloy slab can reach 90% under condition of the present experiment. Microstructure of the slab consist of equal axial grains with 15 approximately 25 μm in diameter and Pb dispersed uniformly in them. After cold or hot rolling of the slab with reduction of 50 approximately 60%, the microstructure can be densified. The rolled Al-Pb alloy plate can be compacted together with pure Al plate very well.
文摘The paper studies the probability of industrial application of vibration liquefaction of bulk solid from the opposite point of view, and proposing turning its harmful effects into benefits. Utilizing a new device of vibration liquefaction and by compacting saturated bulk solid, a set of additional device for experiment was designed. These experiments examined the problems related to vibration liquefaction of fine ores and tailings on the basis of DSA 1 type direct shear apparatus, including models of straight tubes, curved tubes and a sandbox. The changing properties of tailings under vibration and the mechanism of vibration liquefaction and compacting of tailings were studied, and future application of the technique to mines has been put forward.
文摘In the present scenario,computational modeling has gained much importance for the prediction of the properties of concrete.This paper depicts that how computational intelligence can be applied for the prediction of compressive strength of Self Compacting Concrete(SCC).Three models,namely,Extreme Learning Machine(ELM),Adaptive Neuro Fuzzy Inference System(ANFIS)and Multi Adaptive Regression Spline(MARS)have been employed in the present study for the prediction of compressive strength of self compacting concrete.The contents of cement(c),sand(s),coarse aggregate(a),fly ash(f),water/powder(w/p)ratio and superplasticizer(sp)dosage have been taken as inputs and 28 days compressive strength(fck)as output for ELM,ANFIS and MARS models.A relatively large set of data including 80 normalized data available in the literature has been taken for the study.A comparison is made between the results obtained from all the above-mentioned models and the model which provides best fit is established.The experimental results demonstrate that proposed models are robust for determination of compressive strength of self-compacting concrete.
文摘This study examined the relationship between selected physico-mechanical properties, compacting pressure and mixing proportion of briquettes produced from combination of maize cob particles and sawdust of low, medium and high density timber species. Particle sizes of maize cobs and sawdust used for the study were ≤1 mm. The two materials were combined at mixing percentages of 90:10, 70:30 and 50:50 (Sawdust:maize cobs). Briquettes were produced at room temperature (28°C) using compacting pressures 20, 30, 40 and 50 MPa. The results suggested that combining maize cob particles with sawdust of low, medium and high density wood species could significantly enhance the relaxed density, compressive strength in cleft and impact resistance index of briquettes produced from agricultural biomass residue like maize cobs. The results further indicated that the physical and mechanical characteristics of briquettes produced from combinations of sawdust of low density species and maize cobs were exceptionally higher than that produced from combinations of maize cob particles, and medium density and high density timber species. The R2 values for the regression model between the independent variables (mixing percentage and compacting pressure) and relaxed density, compressive strength in cleft and impact resistance index of briquettes produced from combinations of maize cob particles and sawdust of low density species (Ceiba pentandra) were 0.966, 0.932 and 0.710 respectively. This study provides a hope for briquetting maize cobs at room temperature using a low compacting pressure.
文摘A short term field mesocosm experiment was performed in semi-deciduous forest areas of Ivory Coast to assess the impact of a decompacting （Hyperiodrilus africanus, Eudrilidae） and two compacting （Millsonia omodeoi and Dichogaster terrae nigrae, Acanthodrilidae） earthworm species on soil properties. These species have been selected for their predominance in the re- gion and their contrasting impact on soil structure. The experimental design consisted of a treatment without worms （control）, and treatments with one, two or three species of earthworms. Both compacting and decompacting earthworms increased water infil- tration rate in all treatments, with marked impact in H. africanus and M. omodeoi＋D, terraenigrae treatments. Interactions be- tween compacting and decompacting species resulted in more large aggregates in comparison to when the compacting species D. terraenigrae was alone. This may be accounted for by their compacting attribute as compacting earthworms are responsible for producing the highest number of large aggregates. The low values of mean weight diameter in treatments combining decompact-ing and compacting earthworms compared with compacting ＂M. omodeoi＂ one also confirmed the trend of decline in soil com-paction in the presence of the decompacting species. These results showed positive impact of species richness on soil structure regulation, which is crucial in ecosystem productivity and support consequently the insurance hypothesis. In fact, this study showed that the preservation of earthworm species belonging to these two contrasting functional groups is essential for the main-tenance of stable soil structure regulation in agro-tropical ecosystems.
文摘Most of the construction materials research now concerns on investigation of construction materials that is locally produced at a rate and cost compatible with the pace of construction. The present paper is concerned with investigation of fresh and hardened properties of self-compacting concrete (SCC) produced from local available materials in JORDAN. The produced SCC contains the local stone cut waste powder which is called Al-KHAMKHA in JORDAN with different replacement of (0%, 10%, and 25%) of fine silica aggregate;?the study also investigatesthe effects of SP33 super?plasticizer which is used by different doses (1%, 1.5% and 2%) for cement. The slump flow and the compressive strength of SCC were studied and the experimental results indicate the possibility of using Al-KHAMKHA in the production of SCC as the results showed that the compressive strength of the SCC with 10 % replacement by al-khamkha together with 1% SP33?super plasticizer was higher compared to pure SCC without al-khamkha;?the results also showed that as al-khamkha content increased the slump flow decreased.
文摘The technology of concrete has significantly increased in recent years through the use of super plasticizer and availability of mineral additions. One of the most recent materials used as an additive, replacing a portion of cement in concrete, is fine clay fired at a temperature of 800℃ to 900℃. This research is based on trials that complied with artificial pozzolan (waste crushed brick), and their effect on the rheological and mechanical behavior of mortar. The addition of 5% of a waste crushed brick has helped not only to improve the strength (tensile and compression), but also to foster a better rheological behavior in terms of fluidity and stability, with a low heat of hydration compared to control. However, tests of optimizing the content of self-compacting concrete (SCC) in coarse aggregates, sand and binder, led us to confirm that the combined mass of more optimal (better workability and stability) is that based on low in volumetric percentage of sand/paste with a granular skeleton richest gravel low dimensions (2/3 of G 3/8 and 1/3 of G 8/15).
文摘This paper presents the results of experimental investigations on mechanical properties of self compacting concrete made with local materials. The used materials were cement, aggregate and super plasticizer. Limestone powder, silica fume and blast furnace slag have been used as adjuvant in self compacting concrete (SCC). Self compacting concrete properties in fresh and hardened state are characterized and analyzed. The test results indicate the possibility to manufacture SCC with good rheological and mechanical properties using local materials.
文摘This study proposed a new way to formulate a low energy super-sulfated cement (SSC) which can be used to produce self-compacting concrete (SCC) with high compressive strength and durability in terms of chloride penetration resistance. This innovative SSC, different from the traditional SSC, was purely produced with a ternary mixture of three industrial by-products of ground granulated blast furnace slag, low calcium Class F fly ash and circulating fluidized bed combustion (CFBC) fly ash and was denoted as SFC-SSC (super-sulfated cement made by mixture of slag, Class F fly ash and CFBC fly ash). Experimental results showed that the combination of a fixed amount of 15 wt.% of CFBC fly ash with various ratios of Class F fly ash to slag could be used to produce the hardened SCCs with high 28-day compressive strengths (41.8 - 65.6 MPa). Addition of Class F fly ash led to the resulting SCCs with lowered price and preferable engineering properties, and thus it was considered as state-of-the-art method to drive such type of concrete towards sustainable construction materials.
文摘Wood and fly ash were observed to have significant qualities that could improve the strength of self compacting concrete.The material was applied to increase the compressive strength of concrete strength.This material could be the demanding material for partial replacement for cement.The study observed the behaviour of the material from experts that applied these material through experimental investigation,but the study monitored the behaviour of this material by applied modeling and simulation to determine other effect that could influence the behaviour of these materials in compressive strength.This was to determine the significant effect on the addictive applied as partial replacement for cement.Lots of experts have done works on fly ash through experiment concept,but the application of predictive concept has not been carried out.The adoption of this concept has expressed other parameters that contributed to the efficiency of wood and fly ash as partial replacement for cement on self compacting concrete.The study adopting modeling and simulation observed 10 and 20%by weight of cement as it is reflected on its performance in the simulation,from the simulation wood recorded 10%as it was observed from the growth rate of this self compacting concrete reflected from the trend.The simulation for model validation was compared with the works of the studies carried out[20].And both values developed best fits correlation.
基金Key Science and Technology Planning Project by Science & Technology Department of Hubei Province (No. 2004AA101C92).
文摘The engineering characteristics of weathered soft rock are important contents of soft rock mechanics. They also play a significant role in compacting deformation, which has been known to exert a significant amount of influence on the stability of highway filling subgrade engineering. In an effort to investigate this aspect of the problem, compacting tests and unconfined compressive strength tests have been carried out on weathered argillaceous slate and pelitic siltstone rocks, which are broken and graded before the test. The testing results indicate that the relationships of both between stress and strain and between axial strain and tangent modulus are exponential relationships; the size of the grain plays some influence on the deformation modulus, whereas the water content impacts the compressive strength greatly, which shows quadratic function; the unconfined compressive strength is linear with the dry density of loose soft rock mixtures. Therefore, the water content must be controlled in both the design and the construction of subgrade engineering of soft rock filling, and at the same time some effective measures should be taken to reach the requirement of compaction.
基金the Ministry of Higher Education for funding this research
文摘A new automatic rotary compactor and its abilities in compacting stone mastic asphalt （SMA） are presented. Following an overview of the rotary compactor and the compaction procedure, it is demonstrated that the rotary compactor is able to produce uniform slabs with the desired thickness of 65 mm all over around. Furthermore, 132 cored samples from the rotary compactor had been compacted uniformly with approximately 4% optimum air void content. In addition, performance tests results indicate that the rotary compactor produces asphalt mixturures with the requirements of resilient modulus, Marshall stability and flow. A weight factor was introduced for each fraction of aggregates in the degradation analysis to compensate the crushing effect of aggregates during mixing and compacting.
基金the National Natural Science Foundation of China.
文摘It is well known that the properties of material are determined by its structure and the interior atomic state. Nanosolid material is no exception either. Many unusual properties of nanosolid are indeed due to its particular interfacial structuret. There are a large number of unsaturated coordination atoms located at the interface of nanosolids, and these atoms form a special interfacial structure with different types of bonds. As an
文摘Parallel loops account for the greatest amount of parallelism in numerical programs.Executing nested loops in parallel with low run-time overhead is thus very important for achieving high performance in parallel processing systems.However,in parallel processing systems with caches or local memories in memory hierarchies,“thrashing problem”may arise when data move back and forth frequently between the caches or local memories in different processors.The techniques associated with parallel compiler to solve the problem are not completely developed.In this paper,we present two restructuring techniques called loop staggering,loop staggering and compacting,with which we can not only eliminate the cache or local memory thrashing phenomena significantly,but also exploit the potential parallelism existing in outer serial loop.Loop staggering benefits the dynamic loop scheduling strategies,whereas loop staggering and compacting is good for static loop scheduling strategies,Our method especially benefits parallel programs,in which a parallel loop is enclosed by a serial loop and array elements are repeatedly used in the different iterations of the parallel loop.
基金The experimental work of the present study was undertaken at the Concrete Laboratory of Rafsanjan University,IranThe authors are pleased to acknowledge the Vali-e-Asr University of Rafsanjan support.
文摘With increasing environmental pressure to reduce solid waste and to recycle as much as possible,the concrete industry has adopted a number of methods to achieve this goal by replacement of waste glass with concrete composition materials.Due to differences in mixture design,placement and consolidation techniques,the strength and durability of Self Compacting Concrete(SCC)may be different than those of conventional concrete.Therefore,replacement of waste glass with fine aggregate in SCC should deeply be investigated compared to conventional concretes.The aim of the present study is to investigate the effect of glass replacement with fine aggregate on the SCC properties.In present study,fine aggregate has been replaced with waste glass in six different weight ratios ranging from 0%to 50%.Fresh results indicate that the flow-ability characteristics have been increased as the waste glass incorporated to paste volume.Nevertheless,compressive,flexural and splitting strengths of concrete containing waste glass have been shown to decrease when the content of waste glass is increased.The strength reduction of concrete in different glass replacement ratios is not remarkable,thus it can be produced SCC with waste glass as fine aggregate in a standard manner.
基金supported by the National Key R&D Program of China(2024YFB2605500)the National Natural Science Foundation of China(52308444)the Fundamental Research Funds for the Central Universities(2242024K40036).
文摘In situ density and moisture content of asphalt pavement are essential controlling parameters that require accurate measurement for quality control and quality assurance purposes.The ground-penetrating radar(GPR)technique could provide non-destructive,non-contact,and full-coverage estimations of pavement density and moisture content.However,the technical readiness and drawbacks,including prediction models,signal processing algorithms,and testing hardware,remain unclear for agencies and construction practitioners,impeding large-scale implementations.This paper aims to provide a thorough review of the theoretical background and current practices of using GPR for non-destructive measurements of asphalt pavement density and moisture content during construction,thereby allowing for real-time correction of over-or under-compaction on site.The principles and applications of GPR-based density and moisture content prediction models were comprehensively summarized.Their strengths and limitations were discussed.Cutting-edge GPR equipment suitable for such applications was introduced,including their system components,application scenarios,and inherent limitations.Factors affecting prediction accuracy were analyzed.Advanced signal processing algorithms were discussed in the end,along with the in-place calibration procedure for aggregate dielectric constants.The reviewed technique could be a guiding tool for real-time monitoring of asphalt pavement density and moisture content using GPR,offering practical insights for future development and standardized deployment in construction quality management.
基金funded by the National Natural Science Foundation of China(32471824,32171746,31870522,42477227,and 32560282)the leading talents of basic research in Henan Province(24XM0375)+6 种基金Excellent Youth Creative Research Group Project in Henan Province(252300421002)Foreign Scientists Studio in Henan Province(GZS2025011)MOHRSS National Foreign Expert Individual Projectsand(110000264820258001)Natural Science Foundation of Henan(242300420604)supported by the Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control(2023B1212060002)the High-level University Special Fund(G03050K001)the China Postdoctoral Science Foundation(No.2021M690922).
文摘Soil compaction often imposes stress on root development and plant survival.However,root anatomical responses that enable persistent root growth and functioning under soil compaction remain unclear.We grew 10 herbaceous species differing substantially in lateral root diameter,in soils with low(1.0 g cm^(-3))and high(1.4 g cm^(-3))bulk density,and assessed root traits including root biomass,anatomical structures,and respiration rates.Greater root thickening upon soil compaction was found in species with thicker first-order lateral roots,mainly due to larger cortical cell size.Both xylem vessel diameter and wall thickness increased more in compacted soils in these species.Despite these anatomical shifts,root respiration rate responded little to soil compaction across most species,likely due to the opposite investment in cortical cells and xylem vessels.Notably,root biomass,independent of root respiration rate and anatomical structures,determined whole-plant growth under soil compaction.Our study reveals two independent strategies of root response to soil compaction:anatomical remodeling for mechanical and metabolic maintenance,and root biomass investment for resource acquisition.These findings offer new insights for breeding and selecting species tolerant to soil compaction and highlight multidimensional strategies of plant adaptation to physical stress.
文摘This paper represents experimental work on the mechanical and durability parameters of self-compacting concrete(SCC)with copper slag(CS)and fly ash(FA).In the first phase of the experiment,certain SCC mixes are prepared with six percentages of FA replacing the cement ranging from 5%to 30%.In the second phase,copper slag replaces fine aggregate at an interval of 20%to 100%by taking the optimum percentage value of FA.The performance of SCC mixes containing FA and copper slag is measured with fresh properties,compressive,split tensile and flexural strengths.SCC durability metrics,such as resistance against chloride and voids in the concrete matrix,is measured with rapid chloride ion penetration test(RCPT)and sorptivity techniques.The microstructure of the SCC is analyzed by using SEM and various phases available in the concrete matrix identified with XRD analysis.It is found that when replacing cement with 20%of FA and replacing fine aggregate with 40%of copper slag in SCC,higher mechanical strengths will be delivered.Resistance of chloride and voids in the concrete matrix reaches the optimum value at 40%;and with the increase of dosage,the quality of SCC will be improved.Therefore,it is recommended that copper slag be used as a sustainable material for replacement of fine aggregate.
基金supported by the Major Program of Xiangjiang Laboratory(No.22XJ01009)National Natural Science Foundation of China(Grant Nos.52227815,52078065,and 52178414)the Postgraduate Scientific Research Innovation Project of Hunan Province(Nos.CX20230852 and CX20230848).
文摘Ground penetrating radar(GPR)offers a rapid and non-destructive approach to evaluating asphalt mixtures by capturing variations in their dielectric constant.As a critical electromagnetic parameter,the dielectric constant demonstrates significant potential for assessing the material composition and mechanical properties of asphalt mixtures.However,the relationship between the dielectric constant and mechanical properties remains unclear.To investigate the factors affecting the dielectric constant and its correlation with the mechanical properties of asphalt mixtures,a systematic analysis of the influencing parameters was conducted.Fitting equations were established to quantify the relationships between the dielectric constant and mechanical properties.Firstly,the effects of compaction state,testing frequency,and testing temperature on the dielectric constant were evaluated.Subsequently,forward simulations of GPR were executed on asphalt pavements with diverse air voids and detection frequencies.Finally,a fitting analysis was performed to determine the correlation between the dielectric constant and the dynamic modulus,compressive strength,and splitting tensile strength.The results indicated that the dielectric constant increased with the compaction state,decreased with increasing testing frequency until stabilized,and was insignificantly affected by changes in testing temperature.The change of air void in asphalt pavement has significantly affected the amplitude and timing of electromagnetic wave reflection.A linear positive correlation was identified between the dielectric constant and dynamic modulus as well as compressive strength,while a quadratic positive correlation existed with splitting tensile strength.This study provided theoretical and practical foundations for enhancing the reliability and accuracy of non-destructive testing in asphalt pavement.
基金supported in part by the National Natural Science Foundation of China Grant 11962006the Natural Science Foundation of Jiangxi Province of China Grant 20232BAB204067.
文摘Quantitative detection of sleeve grouting compactness is a technical challenge in civil engineering testing.This study explores a novel quantitative detection method based on ultrasonic time-frequency dual-domain analysis.It establishes a mapping relationship between sleeve grouting compactness and characteristic parameters.First,this study made samples with gradient defects for two types of grouting sleeves,G18 and G20.These included four cases:2D,4D,6D defects(where D is the diameter of the grouting sleeve),and no-defect.Then,an ultrasonic input/output data acquisition system was established.Three-dimensional sound field distribution data were obtained through an orthogonal detection layout and pulse reflection principles.Finally,a novel quantification detection with a comprehensive defect index(DI)was established by comprehensively considering eight feature parameters,such as time-frequency domain Kurtosis factor(KU),Skewness factor(SK),Formfactor(FF),Crest factor(CF),Impulse factor(IF),Clearance factor(CLF),Wavelet packet energy entropy(WPEE),and Hilbert energy peak(HEP).Construct a DI index by quantifying the difference between defect signals and defect free signals in the time-frequency domain.Experimental results show that,under no-defect conditions,the values of feature parameters are significantly lower than those under defect conditions.Among these,the KU,FF,CF,WPEE and HEP exhibit strong correlations with grout sleeve compactness.The proposed DI index in both types of grout sleeves showed good universality with a linear fit goodness of 0.847–0.962.However,G20 the larger inner diameter and length of the sleeve result in a more complex medium effect during ultrasonic propagation,making its DI index more sensitive to defects than the G18 sleeve.Therefore,the presented method is effective for quantitative detection and analysis of the compactness of grouting sleeves.
