Variation In Gradation Research Articles

Investigations on the rheological properties of cement mortar based on fine aggregate characteristic and its extended prediction model

The rheological property of mortar is significantly influenced by its contained fine aggregate morphology characteristic and capable predictive models are limited. This work aims to expand the film thickness theory by developing an index that integrally represents variations in grain shape, gradation, and mix proportions, and elucidates the impact and the mechanism of these multifactorial differences on rheological performance. The quantitative analysis of the aggregate gradation and particle shape differences were performed, which was used to assess the impact of these variations and different mix ratios on the rheological performance of mortars. A correlation between aggregate differences and film thickness was established using specific surface area and void ratio. The result shows that variations in aggregates are accurately assessed by image analysis and consistently reflected in specific surface area and void ratio metrics. Since variations in rheological performance are predominantly governed by differences in film thickness, the disparities among aggregates can be quantified in terms of their impact on rheological properties by considering specific surface area and void ratio, thus translating into variations of film thickness. The differences in rheological properties due to variations in grain shape, gradation, and mix proportions can be comprehensively represented and controlled through an expansion of the film thickness model.

Effect of aggregate gradation variation on mechanical properties of bitumen concrete.

Effect of aggregate gradation variation on mechanical properties of bitumen concrete.

Effect of sand gradations on the fresh properties of 3D printable concrete

Sand is frequently used as a fine aggregate in concrete mixtures, but the performance of concrete can be considerably impacted by regional variations in sand gradation. In this work, the effect of sand gradations on the fresh properties of three-dimensionally printable concrete (3DPC) mixtures was systematically investigated. The binder combinations (cement, fly ash, silica fume, limestone powder, ground granulated blast-furnace slag) and the water/binder ratio were kept constant throughout the trials. The sands used in the mixtures were standard Ennore sand (ES) (grades I, II and III) and locally available river sand (RS). The mini-slump heights and flow values of mixes made with RS and with optimal packing of binary and ternary combinations of the standard ESs were evaluated and compared with those of the unary packing of ESs and RS. A correlation between the fineness modulus of different sand gradations and printable flow time was determined. The influence of sand gradations and fineness modulus on buildability, shape retention, open time and extrudability were evaluated. It was found that the performance of the fresh 3DPC was influenced by the aggregate's gradation and grain size in addition to its fineness. In conclusion, different fine aggregate specifications must be chosen depending on the various 3D printing building conditions and design requirements.

Effect of Gradation Variation on Mixture Properties in Stone Mastic Asphalt Mixtures with Carbon Fiber and Hybrid Aggregate

Due to advantages like abrasion resistance, increased operating and service life, high coarse aggregate content and high resistance to deformation, increased fatigue life, and others, stone mastic asphalt (SMA) mixtures have recently become a popular asphalt pavement type in road sections such as highways, tunnels, and bridges. There hasn't been much research on the topic, despite the fact that gradation significantly affects the performance of SMA combinations. In this study, the experimental findings of three distinct gradations of SMA mixtures with hybrid materials (basalt coarse aggregate, limestone fine aggregate) and carbon fiber were compared. As a result, it was concluded that the hybrid aggregate used with carbon fiber, maximum aggregate size, and coarse aggregate % had a positive impact SMA mixtures.

Thermal buckling in multi-directional porous plates: The effects of material grading and aspect ratio

In the present study, a trigonometric shear deformation plate theory was employed to perform a thermal buckling analysis of multi-directional functionally graded (FG) plates. During the manufacturing of the multi-directional graded plate, the formation of pores is abounded. Hence, the effect of porosity on the buckling performance was investigated by considering the variation of porosity in the plate for power law gradation variation of material properties. The adverse effect of porosity on the material properties was taken into account by employing the rule of mixture relation. Finite element results show that the thermal expansion coefficient is unaffected by the presence of porosity. For simply supported boundary conditions, the non-linear governing equations are solved for different thermal loads such as uniform, linear, and non-linear. A parametric study was performed in which the effect of grading parameters, aspect ratio, and side-to-thickness ratio under variable temperature change was studies. Critical material grading indices for multi-directional plates have been identified that help researchers and industry personnel in fabrication planning.

Construction Quality Control for Rutting Resistance of Asphalt Pavement Using BIM Technology

During the course of building asphalt pavement, a lack of quality control will lead to the abandonment of the asphalt mixtures. One of the most common problems with asphalt pavement is rutting. Improving the construction’s quality is an important measure to reduce rutting. The purpose is to ensure the high-temperature durability of asphalt mixtures during the construction workflow to reduce the waste of asphalt mixtures, as well as to provide a methodology for the current monitoring of the quality based on the building information modeling (BIM). Rutting resistance was appraised utilizing the static uniaxial creep examination. Oblique photography technology was used to obtain terrain data. The software of Revit 2016 was used to build the spatial model of highways and bridges. The results show that the size distribution of particles, the asphalt proportion, and the forming specimen’s temperature are the vital elements influencing the high-temperature behavior. The gradation was identified as the most important factor. The second was the asphalt binder content. Gradation variation should be given more consideration during paving using asphalt mixtures. Furthermore, the developed BIM platform can also monitor rutting resistance to reduce rework during construction.

Giving names to features in geology; the choice between subjective listing or researching objective natural divisions

In literature the English playwright Shakespeare proposed that “a rose by any other name would smell as sweet”. Many geologist are also flexible about the names they apply to features, and are tolerant of both over-simplification and even making mistakes in the naming of formations or other features. It appears that precision of a single noun is considered subservient to the essence of the narrative, such as evaluating a hydrocarbon prospect, or giving an interpretation of history. Here it is argued that naming is important because geology is so rich in nouns, and consequently compound errors in the use of multiple, poorly-defined nouns rapidly degrades overall meaning. It is proposed that without names that are both natural and consistently applied, but also continually improved, the scientific framework soon falls apart. By this we mean that the geological understanding of exploration risk, or geological history, rapidly become too easily accommodating of any new data and thus loses all rigour. Good, natural names are the results of tested concepts and are themselves open to further testing. From such testing comes recognition that in nature there are both gradational variation in series as well as discrete categories. A search for good names is inexorably linked to a better understanding of the features concerned.

Colonial green algae in the Cambrian plankton.

The fossil record indicates a major turnover in marine phytoplankton across the Ediacaran-Cambrian transition, coincident with the rise of animal-rich ecosystems. However, the diversity, affinities and ecologies of Cambrian phytoplankton are poorly understood, leaving unclear the role of animal interactions and the drivers of diversification. New exceptionally preserved acritarchs (problematic organic-walled microfossils) from the late early Cambrian (around 510 Ma) reveal colonial organization characterized by rings and plates of interconnected, geometrically arranged cells. The assemblage exhibits a wide but gradational variation in cell size, ornamentation and intercell connection, interpreted as representing one or more species with determinate (coenobial) colony formation via cell division, aggregation and growth by cell expansion. An equivalent strategy is known only among green algae, specifically chlorophycean chlorophytes. The fossils differ in detail from modern freshwater examples and apparently represent an earlier convergent radiation in marine settings. Known trade-offs between sinking risk and predator avoidance in colonial phytoplankton point to adaptations triggered by intensifying grazing pressure during a Cambrian metazoan invasion of the water column. The new fossils reveal that not all small acritarchs are unicellular resting cysts, and support an early Palaeozoic prominence of green algal phytoplankton as predicted by molecular biomarkers.

Effect of Cement Content and Aggregate Gradation on Compressive Strength, Flexural Strength, and Elastic Modulus of Cement-Treated Base

Cement-treated base (CTB) is an aggregate mixture with relatively low water and cement content for pavement base layers, which can provide a stronger and stiffer base layer and requires a lower thickness than using granular layers but has the potential to form reflective cracks in the surface layer. Therefore, CTB should not be too stiff and the compressive strength needs to be limited. The research was carried out to analyze the effect of variations in cement content, gradation, and mix density on compressive strength, flexural strength, and elastic modulus. This research also analyzed the resistance of flexible pavement structures with CTB to asphalt fatigue and permanent deformation failure using the AUSTROADS 2017 method and the CIRCLY 6.0 program. The stiffness of CTB with Bina Marga gradation is built by the aggregate material (initially stiff), while the stiffness of CTB with FAA gradation is built by cement and the aggregate material tends to give flexible behavior because it is easier to move. The results showed that CTB with FAA gradation and 5% cement content resulting in a 7-day compressive strength of 3,28 MPa was stated as the optimum mix combination because it provides better resistance to fatigue and permanent deformation failure.

Effect of Aggregate Gradation on Asphalt Concrete Properties

Economic expansion is a positive side effect of national highway construction initiatives. So, the plan is to construct these projects rapidly. This calls for premium asphalt. As a result of aggregate gradation variation, numerous asphalt mixes have been rejected and rebuilt on-site in recent decades, resulting in the waste of valuable resources and valuable time. Consequently, the goal of this study was to examine the durability of asphalt mixes where the aggregate gradation ranged from +4% above to 2% below the standard range. The aggregate gradation is inconsistent throughout HMA manufacture. The aggregate is graded at 2, 4, and 6 percent over and below the allowed range. Case in point: the gradation of the control mix design. Marshall There was a quantitative evaluation of mixed properties throughout the design phase. HMA mix performance was evaluated via high temperature and water cycles by vehicle pressure observation and Indirect Tensile Strength (ITS) testing. In hot climates, asphalt with gradations above +4% and 2% of both the higher and lower standard values showed the greatest resilience to water damage and the least rutting. In warm regions, asphalt mixture design will be constrained by the higher aggregate gradation limits.

Differential sex allocation strategies between females and facultative hermaphrodites of Chamaelirium hisauchianum (Melanthiaceae)

Species of Chamaelirium are known to be highly diversified in sexual characters, but there has been no detailed empirical approach to elucidate the mechanism and process of sexual diversification in the genus. This paper reports the results of population‐based analyses on various sexual aspects of C. hisauchianum endemic to Japan. Of the 20 populations surveyed, eight (40%) were composed of facultative hermaphrodites highly labile in sexual expression, exhibiting a wide range of gradational variation from hermaphroditism through andromonoecy to male. The remaining 12 populations (60%) consisted of females and facultative hermaphrodites. In them, 11.8–30.9% (mean 22.2%) of the individuals were female. With no reciprocal sex changes, females and facultative hermaphrodites were regarded as, plausibly genetically determined, discrete sex morphs. In contrast, sexual expression in both sex morphs appeared resource dependent. Besides the difference in floral sexual traits, the average ratio of ovuliferous flowers in females was higher than that in facultative hermaphrodites. The production of ovuliferous flowers by females was less susceptible to both field and cultivated conditions and tended to be significantly relatively higher under unfavorable growing conditions. Females were thus less plastic (or more persistent) in producing ovuliferous flowers (or female organs) than facultative hermaphrodites irrespective of internal and external conditions. In all populations, andromonoecious plants dominated (50.8–100%), which appeared to reflect the high plasticity in sex allocation of facultative hermaphrodites. The different modes of sex allocation were regarded as secondary sex characters and presumably stem from a difference in easiness or attainability of sexual reproduction between the two sex morphs.

Estimation of voids in a multi-sized mineral aggregate for asphalt mixture using the Theoretical Packing Density Model

The asphalt mixture durability and the rutting performance are related to the design parameter called Voids in Mineral Aggregate (VMA). The main objective of this research consists in estimating VMA according to gradation variation thanks to a non-linear packing density model: the Theoretical Packing Density Model (TPDM). The TPDM is derived from the Compressible Packing Model (CPM). Data are from Vavrik’s reference experiments. The TPDM requires only two parameters: the critical cavity size ratio x0 which characterizes the size of the voids in the coarse aggregate and the compaction index K. TPDM estimates are compared with those of another model, the linear-mixture packing model, thanks to the correlation coefficient, the mean absolute error, the root mean square error and the mean square error. These four statistical indicators are worth respectively 94%, 1.50%, 0.62%, 0.38% for the TPDM and 90%, 1.68%, 0.88%, 0.77% for the linear-mixture packing model: the TPDM therefore makes it possible to reduce the most significant deviations between measurements and estimates.

A portable test strip fabricated of luminescent lanthanide-functionalized metal-organic frameworks for rapid and visual detection of tetracycline antibiotics.

Tetracycline antibiotics (TCs) are commonly used antibiotics in the treatment of infections, but their overuse has a negative impact on human health and ecosystems. Thus, the development of a facile and on-site visualization method for TC detection is necessary. Here, we propose the potential of using lanthanide-functionalized metal-organic framework (MOF) composites (Ag+/Tb3+@UiO-66-(COOH)2, ATUC) as a probe for the rapid detection of tetracycline (TC), chlortetracycline (CTC), oxytetracycline (OTC), and doxycycline (DOX) residues, in which UiO-66-(COOH)2 (UC) could be utilized to provide an interaction microenvironment, Tb3+ as recognition units and Ag+ as a fluorescence enhancer. Upon exposure to TCs, significant luminescence quenching of ATUC excited at 255 nm was observed due to the inner filter effect (IFE) and photo-induced electron transfer (PET), and the established strategy has a detection limit (LOD) of 11.0, 20.1, 9.1, and 22.5 nM for TC, CTC, OTC, and DOX, respectively. More importantly, given its portability and conspicuous luminescence color gradation variation, a portable test strip based on ATUC was manufactured and the results could be distinguished immediately by the naked eye and smartphone analysis, allowing for on-site rapid quantitative assay of TCs, not only in the laboratory but also in a point-of-care setting.

Aggregate Gradation Variation on the Properties of Asphalt Mixtures

National highway projects present a crucial role in economic growth, as they have a great influence on the national income. Therefore, the decision makers plan to construct these projects at a rapid rate. To achieve the just aforesaid, the utilization of asphalt of adequate quality and gradation is essential. The key problem which lies in recent decades is that many types of asphalt mixtures are rejected and reconstructed in the site due to the gradation variation of aggregates in the asphalt mixture which waste raw materials, cost and time. Thus, this research seeks to assess the possibility of accepting asphalt mixes with aggregates gradation variation (within the range from +4% above the upper specification limit to −2% below the lower specification limit). A wearing surface mix with gradation 3B was prepared according to the Egyptian code. The gradation variation was presented as the aggregate gradation is out of the specification limits during Hot Mix Asphalt (HMA) production. The aggregate gradations lie above and below the upper and lower specification limits, respectively, by ±2%, ±4% and ±6%. The design gradation of the control mix was included as a reference case. The different mix properties were measured using the Marshall Mix design method. Then, the performance of HMA mixes was evaluated under the effects of high temperature and water cycles through applying wheel loading tracking and Indirect Tensile Strength (ITS) tests. The results show that the 3B mixes with a gradation within a range of +4% to −2% of the upper and lower specification limits recorded the lowest rutting depth and the highest water damage resistance in hot regions compared to ordinary asphalt mixes. In summary, the new aggregate gradation limits will provide a reference for the design of asphalt mixture in hot climate regions.

An investigation of the electrical conductivity of different stone mastic asphalt mixtures

In recent years, many studies on the prevention of icing on highways and airports through the use of electrically conductive asphalt pavements have been carried out. However, although electrical conductivity in asphalt mixtures has been extensively investigated, the gradation in conductive stone mastic asphalt (SMA) mixtures has not yet been studied in detail. The main purpose of this study was to investigate, for the first time, the effect of aggregate gradation variation on the electrical resistivity and temperature change of electrically conductive SMA. Samples of conductive SMA were produced using three different aggregate gradations (series 1A, 2A and 8S) and 5 mm long carbon fibres (0.2% by weight) as the conductive component. Marshall mix design was performed on series 1A, 2A and 8S. The samples were tested for volume resistivity, temperature change under constant electrical voltage and ultrasonic pulse velocity and the results were compared. The results showed that a change in aggregate gradation had a significant effect on the electrical conductivity properties of the conductive SMA, with a denser gradation of the SMA mixture leading to higher electrical conductivity.

A comprehensive particle packing-based design of bituminous mixtures and its mechanical characterisation

ABSTRACT The one-to-one contact of coarse aggregate is considered to be the main source for the resistance to permanent deformation and to an extent to fatigue damage. Therefore, it is imperative that the mixture is placed with an interlocked coarse-aggregate skeleton. The conventional mix design approaches generally follow dense graded aggregate gradations, which target for maximum density without accounting the one-to-one contact of coarse aggregates. The current study describes an approach for analysing particle packing in bituminous mixtures based on the compressible packing model (CPM), which provides an analytical expression for the estimation of aggregate packing density. Three mixtures with chosen particle packing indicators and a conventional dense graded mixture are subjected to repeated load haversine compression at temperatures between 25 ∘ and 55 ∘ for a frequency range of 0.01–25 Hz. Selection of binder content is carried out based on equivalent compactability criteria. The link between the packing density of aggregate gradation, dynamic modulus, phase angle, master curve parameters, and relaxation spectrum is evaluated in this study. It is observed that dynamic modulus at high temperature, and low frequency, the phase angle, master curve parameters and the relaxation spectrum exhibit sensitivity to the variation in aggregate gradation.

Effect of gradation variation on particle transport process in a generalized flash flood gully via CFD-DEM method

Effect of gradation variation on particle transport process in a generalized flash flood gully via CFD-DEM method

Characterizing and Predicting the Resilient Modulus of Recycled Aggregates from Building Demolition Waste with Breakage-Induced Gradation Variation.

Building demolition waste (BDW) has been massively stockpiled due to increasingly rapid urbanization and modernization. The use of recycled BDW as unbound granular base/subbase materials is among the sustainable, cost-effective, and environmentally friendly pavement construction alternatives. The resilient modulus is an important mechanical property of BDW-derived aggregates and mechanistic design input of pavements incorporating BDW. This paper presents the results of a comprehensive laboratory study on the shear strength and resilient modulus characteristics of BDW-derived aggregate materials. A series of monotonic triaxial compression tests and repeated-load triaxial (RLT) tests were conducted with five different gradations representing particle breakage and different stress paths. The apparent cohesion and internal friction angle of recycled BDW aggregates under consolidated drained conditions ranged from 35.3 to 57.5 kPa and from 30.2° to 54.3°, respectively. The apparent cohesion and internal friction angle also increased and decreased non-linearly with the increasing relative content of fine particles, respectively. The resilient modulus of recycled BDW aggregates gradually decreased with increasing relative content of fine particles at the same stress level. Both the deviator stress and confining pressure exhibited significant influences on the resilient modulus, while the effect of confining pressure was more profound. Based on laboratory testing data, a mechanistic-empirical model was developed to predict the resilient modulus of recycled BDW aggregates from gradation and stress-state variables. The findings could be useful for extended engineering applications of BDW in unbound granular pavement base/subbase construction.

Characterization of Properties of Soil–Rock Mixture Prepared by the Laboratory Vibration Compaction Method

This paper presents a study of the properties of soil–rock mixtures (SRM) prepared by the vibration compaction method. First, the results of laboratory experiments and field tests are compared to determine the reasonable parameters of the vibration compaction method (VCM) for soil–rock mixtures. The compaction characteristics, CBR, and resilient modulus of the laboratory-prepared soil–rock mixtures by the static pressure compaction method (SPCM) and vibration compaction method are compared. The effects of the soil to rock ratio and the maximum particle size and gradation on the compaction characteristic, resilient modulus and CBR of soil–rock mixtures prepared by the vibration compaction method are investigated. Finally, field measurements are subsequently conducted to validate the laboratory investigations. The results show that the reasonable vibration frequency, exciting force, and static surface pressure of the vibration compactor for soil–rock mixtures are recommended as 25 Hz, 5.3 kN, and 154.0~163.2 kPa, respectively. Soil–rock mixtures prepared by vibration compaction method has smaller optimum water content and gradation variation and larger density than specimens prepared by the static pressure compaction method, and the CBR and resilient modulus are 1.46 ± 0.02 and 1.16 ± 0.03 times those of specimens prepared by the static pressure compaction method, respectively. The ratio of soil to rock, followed by the maximum particle size, lead obvious influences on the properties of soil–rock mixtures. Moreover, the results show that the CBR and resilient modulus of soil–rock mixtures prepared by vibration compaction method have a correlation of 86.9% and 89.1% with the field tests, respectively, which is higher than the static pressure compaction method.

Variability evaluation of gradation for asphalt mixture in asphalt pavement construction

Variability of gradation for asphalt mixture is always the difficulty faced by the control of pavement construction, involving the pavement performance. The main purpose of this study is to improve the efficiency of detection for gradation variation and clarify the relationship between gradation variation and construction process. The variability of gradation for superpave asphalt mixtures was investigated with nominal maximum aggregate size (NMAS) of 13 mm, 20 mm, and 25 mm in construction. The correlation between the passing percentages at each sieve size and performance of asphalt mixture was first established by coupling grey relational analysis and entropy weight method. A digital image processing technology with multi-thresholds segmentation (DIP-MTS) was developed and verified through the experiment comparison. An approach to reversely calculate the gradation of cold aggregate was established. The mixture gradations during various construction stages were compared. Results illustrate that the passing percentages of sieves with NMAS, 4.75 mm, and 0.075 mm have a significant influence on the pavement performance and should be paid more attention during construction. The detection results of DIP-MTS are closer to the experimental value, and this technology is capable of detecting gradation for moving aggregate. The reverse calculation approach is proved feasible. Gradation variation in transportation is more severe than other construction processes.