Different Types Of Aggregates Research Articles

Relative Compatibility Analysis of Aggregate-Binder Systems in Arkansas against Stripping

Compatibility holds great importance because it can predict the overall performance of asphalt mixtures. Incompatible aggregate-binder duos can result in a weak and friable mix as well as increase mixtures’ stripping potential. Being unaware, local agencies and contractors often struggle with premature pavement failure, which consequently places unexpected strain on the budget. Thus, this study assessed the compatibility among 18 asphalt binders with a performance grade (PG) of PG 64-22, PG 70-22, and PG 76-22, each collected from six different refineries; and eight different types of aggregates (sandstone, novaculite, limestone, and dolomite, each collected from two different quarries). Viscosity, penetration, pH, and work of cohesion values of binders were used to develop a binder ranking system. Similarly, the aggregates were ranked based on physical (specific gravity and absorption), durability (abrasion resistance and soundness), and chemical (pH and surface free energy) properties. Overall relative rankings of aggregates and binders were also provided by assigning weight factors to different tested parameters. A total of 144 aggregate-binder mixture systems were ranked based on their dry and wet work of adhesion values as well as Texas boiling test results. The compatibility ratio (CR) was also computed, and each of the systems was designated A, B, C, or D based on their relative CR values. Upon analysis, three binders (S2B2, S3B1, and S4B1) and three aggregates (DM2, LS2, and DM1) were designated as the most preferable construction materials. CR values predicted LS2, DM1, and DM2 mixtures as the most compatible mixtures. SS2, LS1, and DM2 mixtures showed the highest stripping resistance in the Texas boiling test. These databases are expected to help the agency and asphalt producers to select compatible binders and aggregates for producing durable asphalt concrete.Practical ApplicationsThis study covered a wide variety of aggregates and asphalt binders prevalent in but not limited to Arkansas. A database developed under this project was based on observed individual aggregates’ and binders’ performances as well as their combined performances. The information provided in this study will help contractors and agencies to choose the most appropriate aggregate-binder system within their reach for producing quality asphalt mixtures. By knowing the rankings, state agencies can adjust project budgets and assign timely rehabilitation due to the usage of less compatible aggregate-binder systems. Contractors can tweak the existing mix design if they must use local but inferior materials. This ranking will also help them to select project-specific materials depending on the project’s significance. The refineries as well will have the opportunity to improve their products to be more compatible with local materials.

Construction of Amphiphilic Indocyanine–Green–Based Langmuir Film and Drop–Casting Film with Photoelectric Conversion Properties

Molecular self–assembly is the automatic formation of functional assemblies of different structural components through weak, reversible, non–covalent interactions on the basis of molecular recognition. Amphiphilic molecules have a natural advantage in self–assembly at the gas/liquid interface. In this work, two amphiphilic molecules with a special molecular structure, indocyanine green (ICG) and a derivative of indocyanine green (CCS), were combined with two dye molecules (tetraphenylporphyrin tetrasulfonic acid hydrate (TPPS) and nickel (II) phthalocyanine–tetrasulfonic acid tetrasodium salt (TsNiPc) for self–assembly through the Langmuir–Blodgett (LB) technique. The nanostructure and assembly behavior in ordered self–assembled films are effectively regulated by inducing dye molecules to form different types of aggregates (H– and J–aggregates). In addition, we prepared composite films containing the same functional components using the conventional drop–casting technique and performed a series of comparative experiments with LB films. The degree of hydrophilicity was found to be related to roughness, with LB composite films being flatter and denser, with the lowest roughness and the best hydrophobicity compared to drop–casting films. Notably, the LB films showed better optoelectronic properties under the same conditions, providing new clues for the application of optoelectronic functional ultrathin film devices.

The Influence of Road Pavement Materials on Surface Texture and Friction

This article’s primary goal was to analyze the effect of texture on skid resistance. Surface texture was recorded with a revolutionary device designed to create 3D surface scans, the Static Road Scanner. The skid resistance was represented by a pendulum test value. Measurements were made on three different groups of surfaces. Reference surfaces with known standard grain sizes represented the first group. The second group consisted of specimens made from a different type of aggregate. The last group of surfaces consisted of asphalt specimens made from different sizes and types of aggregates used in a mixture. The test results shed some more light on understanding texture’s effect on surface friction. Although some results were expected, not all of them were proven. For instance, a high level of texture doesn’t necessarily mean high friction. A relatively strong relationship was found between friction and microtexture on the reference surfaces with grain sizes up to 125 µm. However, the relationships between texture and skid resistance on the aggregate and asphalt specimens turned out to be shallow for the investigated samples. For this reason, it was recommended to expand the number of investigated surfaces in further research to ensure sufficiently different levels of texture.

Image-based indices of aggregates for predicting the initial skid resistance of bituminous pavements

The objective of this study is to propose image-based indicators of microtexture and macrotexture for pavement surfaces that can predict the initial skid resistance. To achieve this objective, images of different types of aggregates that were collected from quarries were processed. Based on the outcome of the image processing, suitable indicators of shape, angularity, and surface texture of coarse aggregates were proposed. Skid resistance data were collected from pavements constructed with the aggregates used in the image processing, as well as with different surface course mixes commonly used in India, such as Bituminous Concrete (BC), Stone Matrix Asphalt (SMA), and Gap-Graded Rubberized Bituminous mix (GGRB).Through a detailed investigation of the image processing outcome and field data, this study introduces the Aggregate Surface Texture Index (STI) as a means of quantifying microtexture, which can be obtained by processing images of the aggregate using wavelet decomposition technique. Additionally, the study proposes Shape Index (SI) and Angularity Index (AI) as indicators for macrotexture, which can be obtained from the processing of digital images of aggregates. For determining the skid resistance of newly constructed pavements, the study suggests using the Surface Macrotexture Index (SMI), which can be obtained by processing digital images of the pavement surface. Furthermore, this study proposes statistical models for predicting the initial skid resistance of pavement based on these indicators. Overall, the proposed image-based indicators of microtexture and macrotexture have the potential to provide valuable insights for designing and maintaining safe and durable pavement surfaces.

Laboratory evaluation of environmentally friendly alternative mineral powders for micro-surfacing treatments manufacture

The effectiveness of using alternative environmentally friendly and cost-effective mineral powders to manufacture micro-surfacing treatments is examined. Four mineral powders (calcium carbonate, dolomite, PAVAL, and mineral dust from the recycling of used toner) as well as Portland cement (control) were used. The use of two of them, the PAVAL and the toner, is the main novelty of the present research. Their granulometry by means of an air jet sieve, their density, and their chemical composition by means of X-ray fluorescence (XRF) were obtained. To generalise the findings, two different types of aggregate (siliceous and porphyritic) have been used to manufacture the micro-surfacing treatment. The mixing time, setting and curing characteristics, and workability were analyzed. Additionally, the resistance to the loss of particles by the wet track abrasion was also studied. Likewise, the consistency assessment was done. Finally, the cohesion also was attained. The micro-surfacing treatments manufactured with all the alternative mineral powders comply with the technical requirements. Moreover, they improve the loss of particles, particularly the toner, with a loss of particles between 87% and 280% lower than the control micro-surfacing. Also, they are less hardening-controlling additive demanding. Particularly the PAVAL needs 0.2% of additive while the control micro-surfacing needs 0.6%. These findings are supported by statistical analysis of variance (ANOVA).

Properties of pervious concrete made with different types of waste aggregate-A literature review

Pervious concrete, also known as porous concrete, contains interconnected pores that allow water from various sources to pass through. This type of concrete is generally used for pavement construction to protect the environment. Pervious concrete contains only coarse aggregate and sometime very small amount of fine aggregate. Many researches were conducted to develop an efficient type of pervious concrete with different types and combination of aggregates. In many studies, along with natural stone aggregate, other types of waste materials were also tried to use as a coarse aggregate in the mix design of pervious concrete. Some of waste materials showed very promising characteristics which can be effectively used in the mix design of pervious concrete with double environmental benefits. This review article provides an overview of some of the earlier investigations on pervious concrete made from waste and industrial by-product materials. The relationships between crushing strength, porosity and water permeability of the pervious concrete with different types of aggregate are presented in this paper. Steel slag, recycled aggregate, and palm oil clicker were among the waste materials utilized as aggregate in pervious concrete, showed comparable performance; even in some instances, better performance was achieved than pervious concrete made with conventional natural aggregate. The shape of waste aggregate, described by the elongation and flakiness indices, greatly affects the strength properties and water infiltration rate of pervious concrete. If these indices are high, the strength properties of the pervious concrete are significantly reduced, but the water permeability is significantly increased.

The Effect of Different Types of Aggregate and Additives on the Properties of Self-Compacting Lightweight Concrete

The major aim of this research is study the effect of the type of lightweight aggregate (Porcelinite and Thermostone), type and ratio of the pozzolanic material(SF and HRM) and the use of different ratios of w/cm ratio(0.32 and 0.35) on the properties of SCLWC in the fresh and hardened state. SF and HRM are used in three percentage 5%,10%, and 15% as a partial replacement by weight of cement for all types of SCLWC. The requirements of self-compatibility for SCC are fulfilled by using the high performance superplasticizer (G51) at 1.2liter per 100 kg of cement. The values of air dry density and compressive strength at age of 28 days within the limits of structural lightweight concrete. The air dry density and compressive strength at age of 28 days for w/cm ratio(0.32) for SCLWC of Porcelinit aggregate are 1964 kg/m3 and 29.57 MPa, respectively. The corresponding values for the SCLWC of Thermostone aggregate are 1820 kg/m3 and 25.75 MPa, respectively. The results show that the HRM performance which is locally available is better than SF in production of SCLWC.

Railway ballast aggregate characterization through a new strength index: Preliminary suitability evaluation of an industrial by-product for a railway application

Ballast is a layer of the railway infrastructure that ensures the correct geometric position of track equipment, distributing vertical loads on the underlying layers. Ballast is composed by aggregate grains of adequate grading, containing a consistent number of voids and a medium–low fine content.The aggregates of ballast must be tested in the laboratory to ascertain the suitability for their use under construction or maintenance. In this work, the physical–mechanical characteristics of different types of aggregate (natural and “artificial”) were evaluated to verify their acceptability as ballast under the Italian specifications. All the aggregates came from Italian production plants. One “artificial” aggregate (steel slag) was used to assess if it can be used instead of the natural aggregate on a railway line in Italy. A mixture of natural and artificial aggregates was also tested for comparison purposes. An index from Point Load Test was also assessed to predict the main physical–mechanical characteristics provided by the laboratory tests.The artificial aggregate shows excellent physical–mechanical properties, compared to the natural one, indicating that the tested by-product can replace the natural aggregate. The mixture of natural and artificial aggregates can guarantee the preservation of natural resources and solve supply difficulties of by-products, maintaining very good physical–mechanical characteristics.In general, the Los Angeles index (both before and after the freeze-thawing cycles) shows a good correlation with the Point Load Strength Index for the tested ballast aggregates. Starting from this result, the Point Load Test could be used to characterize ballast aggregates. A statistical analysis was also performed on the other physical–mechanical parameters: a good correlation was found in some cases, indicating that the Point Load Strength Index can provide a first indication of the other physical–mechanical characteristics of ballast aggregates.

Age influence on compressive strength for concrete made with different types of aggregates after exposed to high temperatures

This study investigates the influence of concrete age and the type of coarse aggregate on compressive strength after exposure to high temperatures. Three coarse aggregates were used: crushed clay bricks as recycled aggregates, expanded glass as lightweight aggregates, and normal quartz aggregates. Specimens were initially cured in water for seven days, and then kept in laboratory conditions for different durations (28 days, 120 days, and 240 days). On the age of 120 and 240 days, specimens were exposed to high temperatures ranging from 200 °C to 1000 °C, and their residual compressive strength was determined.Results indicate that the compressive strength tests for the unheated specimens revealed an increase in strength with age, which can be attributed to the hydration of cement and the formation of a denser microstructure. The results of the residual compressive strength tests for concrete with quartz aggregates (M1-QZ) at 120 and 240 days showed a decline with increasing temperature and age. At 120 days, the strength ranged from 74.3% to 16.9%, and at 240 days, it ranged from 83.5% to 23.8%. Similarly, concrete with expanded glass aggregates (M2-EG) demonstrated decreased compressive strength with increasing temperature and age. The strength ranged from 94.3% to 8.6%, and 88.9% to 10.3% at 120 and 240 days, respectively. In contrast, concrete with crushed clay bricks (M3-CB) exhibited more favourable resistance to high temperatures, with a lower compressive strength reduction. The values ranged from 97.9% to 23.1% at 120 days and from 98.7% to 22.2% at 240 days. The reduced compressive strength after exposure to high temperatures can be attributed to the differences in thermal expansion and aggregates and the moisture loss.These findings demonstrate that the coarse aggregate type significantly influences the concrete's residual compressive strength after exposure to high temperatures.

Mesoscopic Mechanical Properties of Aggregate Structure in Asphalt Mixtures and Gradation Optimization.

Particle media are widely used in engineering and greatly influence the performance of engineering materials. Asphalt mixtures are multi-phase composite materials, of which coarse aggregates account for more than 60%. These coarse aggregates form a stable structure to transfer and disperse traffic loads. Therefore, knowing how to adjust the structural composition of coarse aggregates to optimize their performance is the key to optimize the performance of asphalt mixtures. In this study, the effects of different roughness and different sizes on the interlocking force and contact force of coarse aggregates were investigated through means of simulation (DEM), and then the formation-evolution mechanism of the coarse aggregate structure and the role of different sizes of aggregates in the coarse aggregate structure were analyzed. Subsequently, the optimal ratio of coarse aggregates was explored through indoor tests, and finally, the gradation of asphalt mixture based on the optimization of fine structure was formed and verified through indoor tests. The results showed that the major model can effectively reveal the role of different types of aggregates in the fine structure and the relationship between the strength of contact forces between them and clarify that the strength of the fine structure increases with the increase in aggregate roughness. Hence, the coarse aggregate structure can be regarded as a contact force transmission system composed of some strong and sub-strong contact forces. Their formation-evolution mechanism can be regarded as a process of the formation of strong and sub-strong contact forces and the transformation from sub-strong contact force to strong contact force. Moreover, the dynamic stability of the optimized graded asphalt mixture was increased by 30%, and the fracture toughness was increased by 26%.

Single point mutations at the S129 residue of α-synuclein and their effect on structure, aggregation, and neurotoxicity.

Parkinson's disease is an age-related neurological disorder, and the pathology of the disease is linked to different types of aggregates of α-synuclein or alpha-synuclein (aS), which is an intrinsically disordered protein. The C-terminal domain (residues 96-140) of the protein is highly fluctuating and possesses random/disordered coil conformation. Thus, the region plays a significant role in the protein's solubility and stability by an interaction with other parts of the protein. In the current investigation, we examined the structure and aggregation behavior of two artificial single point mutations at a C-terminal residue at position 129 that represent a serine residue in the wild-type human aS (wt aS). Circular Dichroism (CD) and Raman spectroscopy were performed to analyse the secondary structure of the mutated proteins and compare it to the wt aS. Thioflavin T assay and atomic force microscopy imaging helped in understanding the aggregation kinetics and type of aggregates formed. Finally, the cytotoxicity assay gave an idea about the toxicity of the aggregates formed at different stages of incubation due to mutations. Compared to wt aS, the mutants S129A and S129W imparted structural stability and showed enhanced propensity toward the α-helical secondary structure. CD analysis showed proclivity of the mutant proteins toward α-helical conformation. The enhancement of α-helical propensity lengthened the lag phase of fibril formation. The growth rate of β-sheet-rich fibrillation was also reduced. Cytotoxicity tests on SH-SY5Y neuronal cell lines established that the S129A and S129W mutants and their aggregates were potentially less toxic than wt aS. The average survivability rate was ∼40% for cells treated with oligomers (presumably formed after 24h of incubation of the freshly prepared monomeric protein solution) produced from wt aS and ∼80% for cells treated with oligomers obtained from mutant proteins. The relative structural stability with α-helical propensity of the mutants could be a plausible reason for their slow rate of oligomerization and fibrillation, and this was also the possible reason for reduced toxicity to neuronal cells.

Aggregates of Cyanine Dyes: When Molecular Vibrations and Electrostatic Screening Make the Difference.

Aggregates of cyanine dyes are currently investigated as promising materials for advanced electronic and photonic applications. The spectral properties of aggregates of cyanine dyes can be tuned by altering the supramolecular packing, which is affected by the length of the dye, the presence of alkyl chains, or the nature of the counterions. In this work, we present a joint experimental and theoretical study of a family of cyanine dyes forming aggregates of different types according to the length of the polymethinic chain. Linear and nonlinear optical spectra of aggregates are rationalized here in terms of an essential-state model accounting for intermolecular interactions together with the molecular polarizability and vibronic coupling. A strategy is implemented to properly account for screening effects, distinguishing between electrostatic intermolecular interactions relevant to the ground state (mean-field effect) and the interactions relevant to the excited states (excitonic effects). To the best of our knowledge, this is the first attempt to simulate nonlinear spectral properties of aggregates of symmetric dyes accounting for molecular vibrations.

Integration and calibration of UBCSAND model for drained monotonic and cyclic triaxial compression of aggregates

We report on results from triaxial drained monotonic and cyclic compression tests for four different aggregates (gabbro, limestone, demolished concrete, steel slag), and discuss the applicability of UBCSAND model for simulating the relevant non-linear stress-strain curves. First, UBCSAND is integrated analytically for the elastic and plastic volumetric and deviatoric strains, leading to a pair of novel closed-form solutions expressed in terms of hypergeometric functions. These solutions are inherently free of numerical errors and can be used for the evaluation of results from numerical integration. Second, three calibration techniques for the model parameters are presented and compared: (1) a graphical “chart” solution based on results from forward numerical simulations; (2) a numerical approach based on minimization of residuals; and (3) an informed trial-and-error approach based on the analytical solution. Errors in numerical integration of the model are explored by comparing the analytical solution against results from an Euler integration. Variations in the calibrated parameters are discussed for drained monotonic and cyclic triaxial loading considering different types of aggregates.

Photophysical Properties of Anthracene Derivatives

In this tutorial review, we intend to provide the reader with a comprehensive introduction to the photophysical properties of organic compounds with a specific focus on anthracene and its derivatives. Anthracene-based building blocks have attracted the attention of chemists due to their intrinsic luminescent properties. A deep understanding of their interaction with light, including the mechanisms of emission (luminescence, i.e., fluorescence or phosphorescence) and quenching, is crucial to design and generate compounds with precise properties for further applications. Thus, the photophysical properties of different types of aggregates, both in the ground state (J- and H-type) and in the exited state (e.g., excimer, exciplex) will be discussed, finishing with a few examples of dyads and triads.

Prediction of diffusion properties of cement-based materials incorporating recycled rubber aggregates: Effect of microstructure on macro diffusion properties

In recent years, significant progress has been made in the development of new, eco-friendly, cement-based materials. However, predicting their durability from the new material composition is still a challenging task. There have been very few studies of micromechanical models based on micro-geometric features on cement-based materials incorporating recycled rubber aggregates. In this context, a multiscale model using the microstructural characteristics is proposed to predict their diffusion properties. After the description of the physically-based approach, its accuracy is evaluated by comparing the model predictions with experimental results from mortars with different types of aggregates (natural sand and rubber). In the study, it is assumed that diffusion of ionic species occurs primarily through the porous network of the cement matrix, but also takes place at the matrix-aggregate interface transition zone (ITZ). The method used for modelling is based on homogenization schemes and the spherical n-phase inclusion model which allow the ITZ to be taken into account.

Geotechnical and petrographic properties of carbonate sedimentary rocks from Sasaj region (Ionian Zone) and their use as aggregates for road pavement

This paper is a part of the master’s thesis with the title “Geotechnical and petrographic properties of carbonate sedimentary rocks from different zones of Albania regarding their use as aggregates for road pavement” where this topic presents a particular method of study of limestones and dolomite aggregates from the point of view of their petrographic characteristics, the petrography being an important working tool which proves to be indispensable alongside the classical geotechnical study currently used in Albania. Our work was born from the need to demonstrate that the studies carried out by engineering, geotechnics and geomechanics should not lack synthetic reports on the different types of aggregates used in Albania, especially those of carbonate origin. Moreover, our goal was to take a step forward to fill this gap by accurately correlating the general geological knowledge and the lithological and petrographic characteristics of carbonate rocks with the engineering properties of the aggregates produced from these types of rocks. It is well known that petrography is focusing on details invisible to the naked eye, and therefore, for rock materials selected for the production of aggregates, this microscopic analysis is also necessary, as well as other laboratory analyses, if necessary to verify the stability of these aggregates. Concretely, in this paper we will present a part of our results which show the methods which we used in the analysis of materials from samples of carbonate rocks coming from Sasaj region, one of the four carbonate rock formations that we studied in our master thesis, these formations belonging to four different geological tectonic zones of Albania: Mirdita, Albanian Alpes, Kruja and the Ionian zones. The complete material will be the subject of a more detailed paper for a high impact international journal.

Influence of Elevated Temperatures on the Compressive Strength of Concrete Made with Different Types of Aggregate

Influence of Elevated Temperatures on the Compressive Strength of Concrete Made with Different Types of Aggregate

Investigation of thermal performance of newly multilayer wall/roof constructions for low-carbon buildings

Increasing concerns about energy consumption for heating and cooling of buildings have made it necessary to improve the thermal performance of building materials. However, in addition to using materials with high insulation characteristics, an accurate calculation of the capacities of the heating and cooling systems is also an important factor in ensuring high energy efficiency for low-carbon buildings. The devices will not be selected at capacities larger than the capacities that should be on this point and energy wastage will be prevented. To achieve this goal, in this study, investigations are carried out to produce new concrete types with high thermal insulating characteristics. Besides, many new concrete wall and roof samples were produced with different types of aggregates at different volume ratios and their thermophysical characteristics are tested in accordance with ASTM and EN standards. To estimate the thermal performance of produced samples, a periodic solution method, the Complex Finite Fourier Transform technique, is developed by using thermophysical characteristics data of those structures. The results showed that the daily heat gain values were calculated as 65.909 W/m2 for the EPC50 wall and 11.324 W/m2 for the PC40-EPC60 wall with 20 cm thicknesses.

Surface Modification of Steel Slag Aggregate for Engineering Application in Asphalt Mixture

The proper disposal of steel slag has always been a great challenge for the metallurgical industry in China and around the world. In this work, the steel slag aggregate (SSA) was surface pretreated (PSSA) and applied into asphalt mixture. The adhesive behavior between the bitumen and five different types of aggregates (i.e., limestone, diorite, diabase, SSA, PSSA) were evaluated based on the contact angle and binder bond strength tests. The pavement performance of three asphalt mixtures which contain normal aggregate, SSA and PSSA respectively, was analyzed by Marshall stability test, wheel-tracking rutting test, low-temperature bending creep test and water sensitivity test. The results showed that surface modification can improve the surface properties of SSA, reduce its contact angle with bitumen, and eventually lead to the improvement of adhesion between them. In addition to the satisfied low-temperature properties, PSSA was found to significantly improve the anti-rutting property and reduce the water sensitivity of asphalt mixture. This work is expected to promote an alternative application for recycling of SSA in pavement engineering.

Forecasting for lead-time period by temporal aggregation: Whether to combine and how

Temporal aggregation (TA) refers to transforming a time series from higher to lower frequencies (e.g. monthly to quarterly). There are two different types of aggregation: overlapping and non-overlapping; which, when added to the option of using original time series, present the forecaster with three approaches to produce required forecasts over the lead-time period: (i) non-overlapping aggregation (NOA) (ii) overlapping aggregation (OA); and (iii) bottom-up to aggregate forecast (BU). Forecasters may then need to decide which approach to use or alternatively combine the forecasts generated by the three approaches, instead. In this study, we design and execute an experiment using the M4 competition dataset, to explore the effect of different initial frequencies (i.e. daily, monthly, and quarterly), data aggregation levels and combination methods on forecast accuracy. We are surprised to find that neither temporal aggregation strategies have an overall gain on forecasting accuracy. Equally concerning is the fact that straight (average) combinations of these forecasts are similarly of no benefit to the accuracy. To extract the benefits of both well-supported individual forecasting practices of temporal aggregation and combination, we propose a framework that aims to combine temporal aggregation and forecasting combinations using a polynomially weighted average with multiple learning rates. We find considerable overall improvement in forecasting accuracy by using the proposed combination, especially for longer lead-times. We discuss areas where the framework is expected to perform best in the future and conclude that further research is required in this area. We note that our method can work in parallel of others and close with an agenda for further research on forecasting by temporal aggregation.