Different Types Of Aggregates Research Articles

FEATURES OF CREATION OF THE SMART MONITORING SYSTEMS FOR MICROGRIDS

In this paper, an analysis of the main requirements for control systems in Microgrid is conducted. The main objectives of the implementation of Microgrid systems were determined and, based on the performed analysis, the requirements for Smart-monitoring systems were systematized. The components of Smart-monitoring systems, which include: communication software platform, hardware communication platform and types of equipment of DG sources for Microgrid systems were analyzed. It is proposed to build Smart-monitoring systems for Microgrid systems on the basis of the SGAM model, taking into account various models of aggregation of different types of DG sources within the framework of Microgrid systems. The proposed structure of the Smart-monitoring system for Microgrid systems with various DG sources makes it possible to effectively aggregate DG sources and prosumers and to carry out effective dispatching of generating capacities based on market mechanisms of their interaction with consumers and among themselves.

Candida auris undergoes adhesin-dependent and -independent cellular aggregation.

Candida auris is a fungal pathogen of humans responsible for nosocomial infections with high mortality rates. High levels of resistance to antifungal drugs and environmental persistence mean these infections are difficult to treat and eradicate from a healthcare setting. Understanding the life cycle and the genetics of this fungus underpinning clinically relevant traits, such as antifungal resistance and virulence, is of the utmost importance to develop novel treatments and therapies. Epidemiological and genomic studies have identified five geographical clades (I-V), which display phenotypic and genomic differences. Aggregation of cells, a phenotype primarily of clade III strains, has been linked to reduced virulence in some infection models. The aggregation phenotype has thus been associated with conferring an advantage for (skin) colonisation rather than for systemic infection. However, strains with different clade affiliations were compared to infer the effects of different morphologies on virulence. This makes it difficult to distinguish morphology-dependent causes from clade-specific or even strain-specific genetic factors. Here, we identify two different types of aggregation: one induced by antifungal treatment which is a result of a cell separation defect; and a second which is controlled by growth conditions and only occurs in strains with the ability to aggregate. The latter aggregation type depends on an ALS-family adhesin which is differentially expressed during aggregation in an aggregative C. auris strain. Finally, we demonstrate that macrophages cannot clear aggregates, suggesting that aggregation might after all provide a benefit during systemic infection and could facilitate long-term persistence in the host.

PROPERTIES OF CONCRETE AND FIBER-REINFORCED CONCRETE FOR BASES OF ROAD CLOTHES BASED ON SECONDARY AGGREGATES WITH HETEROGENEOUS COMPOSITION

The problem of disposal of concrete scrap of dismantled building structures is relevant for most countries of the world. For Ukraine, this problem is even more acute due to the significant amount of destruction caused by hostilities and rocket attacks. In current research the properties of concrete and fibre-reinforced concrete for the bases of road clothes based on natural and secondary aggregates were compared: granite river gravel, secondary crushed stone with a heterogeneous composition, quartz sand and secondary sand from recycled reinforced concrete structures. CEM III/A slag Portland cement with a blast furnace slag content of 65% and a polycarboxylate type superplasticizer were used. Three series of samples were studied: without fibre; with glass fibre ANTI-CRAK HP 12 (length 12 mm, diameter 0.017 mm, equivalent thread diameter 0.3 mm) in the amount of 1 kg/m3; with polypropylene fibre BeneSteel 55 (length 55 mm, equivalent thread diameter 0.48 mm) in the amount of 4 kg/m3. In each series, concrete on granite gravel and quartz sand, concrete on secondary crushed stone and quartz sand, concrete on secondary crushed stone and secondary sand were studied. The workability of all mixtures was equal to S1. Due to the use of different types of aggregates and fibres, the W/C of concrete mixtures differed significantly. Concretes on secondary aggregates had a higher W/C than on natural aggregates. When using the Anti-Crak HP 12 fibre, the mobility of mixtures with equal W/C increased by 5.5 – 6.9 %. When using BeneSteel 55 fibre, W/C increased by 10.6 – 15.5 %. The type of aggregate had a significant effect on the average density of concrete. When using secondary crushed stone and quartz sand, the average density decreased by 3.8 – 4.6 %. When using secondary crushed stone simultaneously with secondary sand, the average density of concrete decreased by 5.2 – 8.5 %. When using Anti-Crak HP 12 fiber, the average density of concrete decreases by 2 %, when using BeneSteel 55 fibre – up to 4.1 %. Concretes on secondary crushed stone with heterogeneous composition and quartz sand had 4 % higher compressive strength and 2 % higher tensile strength in bending than concretes on granite gravel and similar sand (29.8 MPa and 3.18 MPa, respectively). When secondary crushed stone is used simultaneously with secondary sand, the compressive strength of concrete is only 1.1 % lower than the strength of concrete on natural aggregates, and the tensile strength in bending is 10 % lower. This confirms the possibility of effective use of these concretes for arranging of bases of road clothes. The high-quality performance of secondary aggregates in concrete explains due to their better adhesion to the cement-sand matrix. Dispersed fibre reinforcement with Anti-Crak HP 12 has a positive effect on the compressive strength of concrete on all types of aggregate and increases the tensile strength of concrete on natural aggregates. The use of BeneSteel 55 fibre was not effective due to a significant increase in the W/C of the mixture when it was introduced. In general, taking into account the economic factor, dispersion reinforcement of concrete on secondary aggregates with the types of fibres used in the research is not advisable.

Using tribological approach to assess production temperatures of asphalt binders

In this study, ball on three plates (BOTP) experiment has been used to propose an approach for evaluating the mixing and compaction temperatures of asphalt binder. The results are compared and correlated with equi-viscous- and workability- based methods to arrive at the proposed criterion. A viscosity grade binder, VG30, was modified with varying dosages of Sasobit and Rediset, and the study was executed considering two different types of aggregates (Granite and Dolerite). It was found that warm mix asphalt (WMA) binders can reduce the production temperatures of VG30, irrespective of the test methodology. Equi-viscous method was found to be inappropriate in the quantification of the production temperatures of WMA binders. Workability test results indicated that reduction in mixing and compaction temperatures is a function of the type of warm mix additive, dosages used, and aggregate source. Based on the variability of test parameters in BOTP test, a normal load of “1 N” and a sliding speed of “0.3 m/s” were found to give consistent results of coefficient of friction (CoF). The effect of plate type (Granite, Dolerite, and steel) on the values of CoF was found to be insignificant, and the use of steel plates was recommended. The results of BOTP and workability were in good agreement with each other. Temperature ranges corresponding to the CoF of “0.255–0.282” and “0.317–0.350” are proposed for assessing the mixing and compaction temperatures, respectively.

Prediction model of the mortar’s yield stress based on the aggregate’s volume fraction and properties

Yield stress is an important performance parameter for cement-based materials. Nonetheless, the prediction and regulation of the yield stress using current models still requires the execution of the rheological tests at the corresponding scales (mortar or concrete), which is time-consuming and costly. This paper proposes a model for cement-based materials' (at the mortar scale) yield stress based on theoretical analysis and a multi-scale approach. This model demonstrates that mortar's yield stress can be expressed as a function of the aggregate's properties (specific surface area, volume fraction, size, and packing density) and the yield stress of a cement paste with the same water-to-cement ratio as the mortar. In addition, the model's fitting parameters are fixed for different types of aggregates. Validation tests revealed that the proposed model can accurately predict the mortar's yield stress. Finally, a relationship between relative yield stress and relative plastic viscosity is established, providing useful information for regulating the rheological properties of a given mortar.

The Influence of Different Aggregates on the Physico-Mechanical Performance of Alkali-Activated Geopolymer Composites Produced Using Romanian Fly Ash.

In light of the urgent need to develop environmentally friendly materials that, at some point, will allow the reduction of concrete and, consequently, cement consumption-while at the same time allowing the reuse of waste and industrial by-products-alkali-activated fly ash (AAFA) geopolymer composite emerges as a material of great interest. The aim of this study was to investigate the physico-mechanical performance of composites based on AAFA binders and the effect of different types of aggregates on these properties. The experimental results indicate variations in flexural and compressive strength, which are influenced both by the nature and particle size distribution of aggregates and the binder-to-aggregate ratio. The analysis of the samples highlighted changes in porosity, both in distribution and pore size, depending on the nature of the aggregates. This supports the evolution of physico-mechanical performance indicators.

Preparation and Performance Investigation of Epoxy Resin-Based Permeable Concrete Containing Ceramsite.

Permeable concrete is an innovative type of concrete that provides a sustainable solution for stormwater management by allowing water to seep through and be filtered naturally. This study focuses on the preparation and performance investigation of an epoxy resin-based permeable concrete containing ceramsite. In this study, ceramsite, a lightweight aggregate, is used as a substitute for conventional aggregates in the concrete mixture. The epoxy resin is then added to improve the strength and durability of the concrete. A series of tests, including compressive strength, water permeability, and freeze-thaw resistance tests, are conducted to evaluate the performance of the epoxy resin-based permeable concrete. The results show that with an increasing epoxy resin binder-aggregate ratio, the compressive strength of the epoxy resin-based permeable concrete significantly increases while the permeability coefficient decreases. Different types of aggregates have varying effects on the compressive strength and permeability coefficient of epoxy resin-based permeable concrete, with high-strength clay ceramsite providing the highest compressive strength and lightweight ceramsite having the highest permeability coefficient. In addition, the discrete element simulation method effectively and feasibly determines the ultimate load and accurately simulates the compressive strength of the permeable cement-based mixture, consistent with the measured compressive strength. A quadratic polynomial regression analysis yielded an R2 value of around 0.93, showing a strong relationship between durability and freeze-thaw cycles. The findings contribute to the development of sustainable construction materials for stormwater management and offer potential applications in various infrastructure projects.

Infliximab aggregates produced in severe and mild elevated temperature stress conditions induce an extended specific CD4 T-cell response

Aggregation has been widely described as a factor contributing to therapeutic antibody immunogenicity. Although production of high-affinity anti-drug antibodies depends on the activation of CD4 T lymphocytes, little is known about the T-cell response induced by antibody aggregates, especially for aggregates produced in mild conditions resulting from minor handling errors of vials. Large insoluble infliximab (IFX) aggregates produced in severe elevated temperature stress conditions have been previously shown to induce human monocyte-derived dendritic cell (moDC) maturation. We here showed that large IFX aggregates recruit in vitro a significantly higher number of CD4 T-cells compared to native IFX. Moreover, a larger array of T-cell epitopes encompassing the entire variable regions was evidenced compared to the native antibody. We then compared the responses of moDCs to different types of aggregates generated by submitting IFX to mild conditions of various times of incubation at an elevated temperature. Decreasing stress duration reduced aggregate size and quantity, and subsequently altered moDC activation. Of importance, IFX aggregates generated in mild conditions and not altering moDC phenotype generated an in vitro T-cell response with a higher frequency of CD4 T cells compared to native IFX. Moreover, cross-reactivity studies of aggregate-specific T cells showed that some T cells could recognize both native and aggregated IFX, while others responded only to IFX aggregates. Taken together, our results suggest that aggregation of antibodies in mild elevated temperature stress conditions is sufficient to alter moDC phenotype in a dose-dependent manner and to increase T-cell response.

Toward the flow-centric detection of browser fingerprinting

Browser fingerprinting has become a prevalent technique employed by websites for advertising and analytics. It utilizes JavaScript objects and APIs to gather traditional and non-traditional browser attributes and creates unique identifiers for online user tracking. While previous research has examined the invocation of the browser's built-in JavaScript objects and APIs to retrieve browser attribute values, it overlooks the use and flow of those values within scripts.In this paper, we define browser fingerprinting behavior as the aggregation of different types of browser attributes, and reduce the detection of browser fingerprinting to a joint analysis of the data flows of browser attribute values in JavaScript code. FProbe, our proposed framework for the flow-centric detection of browser fingerprinting, performs context-sensitive static data flow analysis on JavaScript code. Given the complexity and dynamic features of the JavaScript language, achieving soundness in static analysis of JavaScript code is extremely challenging or even impossible. Consequently, FProbe aims to be a practical and accurate tool for detecting browser fingerprinting. We implemented FProbe in Java and evaluated its performance using 4,296 fingerprinting scripts from recent work and 2,335,317 pieces of JavaScript code on 988,220 websites. FProbe achieved F-measures of 97.81% and 96.31% on these datasets, respectively. It identified browser fingerprinting behavior on 0.78% of the 988,220 websites, with the use of the toDataURL method observed in 4.26% of the fingerprinting scripts. Notably, only 72 fingerprinting scripts and 10 fingerprinting providers identified by FProbe were reported in previous work. These results highlight the effectiveness of FProbe in detecting browser fingerprinting and its complementarity to existing detection tools. Additionally, our comprehensive study demonstrates that fingerprinting with traditional browser attributes can achieve a 96.6% F-measure.

α-Synuclein Drives Tau's Cytotoxic Aggregates Formation through Hydrophobic Interactions.

Tau and α-synuclein are proteins involved in pathologies known as tauopathies and synucleinopathies, respectively. Moreover, evidence shows that there is a crosstalk between them as is seen in the brains of individuals with sporadic neurodegenerative disorders. Based on that, we present data showing that the hydrophobic α-peptide 71 VTGVTAVAQKTV82 induces the aggregation of the full-length tau fragment in the absence of heparin assessed by ThT. Moreover, AFM images reveal the presence of straight filaments and amorphous aggregates of full-length tau in the presence of the α-peptide. Additionally, ITC experiments showed the interaction of the α-peptide with tau full-length (441 amino acids),4R (amino acids from 244 to 369), and both hexapeptides 275 VQIINK280 and 306 VQIVYK311 through hydrophobic interactions. The Raman spectroscopy spectra showed conformational changes in the Amide region in the aggregates formed with full-length tau and α-syn peptide. Furthermore, the incubation of extracellular aggregates with N2a cells showed morphological differences in the cellular body and the nucleus suggesting cell death. Moreover,, the incubation of different types of aggregates in cell culture provokes the release of Lactate dehydrogenase (LDH). Altogether, we found that α-synuclein peptide can drive the aggregation of full-length tau-provoking morphological and structural changes evoking cytotoxic effects.

Impact of internal structure on aggregate collisions

ABSTRACT Granular-mechanics simulations are used to study collisions between granular aggregates. We compare the collision outcomes for three different types of aggregate: (i) aggregates constructed by a ballistic particle–cluster aggregation (BPCA) process, and two homogeneous spherical aggregates which differ by their grain coordination. All aggregates contain the same number of grains and (central) filling factor. We find that BPCA aggregates have a slightly decreased growth velocity for central impacts. After scaling the collision velocities to the growth velocity for central impact and the impact parameter to the gyration radius, our collision results show a remarkable degree of agreement for the aggregates studied. Also, the collision-induced compaction as well as the size of fluctuations during the collision process are identical for all aggregate types. Even at glancing collisions, the larger extension and rough surface of BPCA aggregates do not cause major changes as compared to homogeneous aggregates with a well-defined and smooth surface. However, monomer ejection during the collision is enhanced for BPCA aggregates. This study thus shows that details of the internal aggregate structure are of little importance in collisions of granular aggregates, except for grain ejection.

Renewable Energy Community with distributed storage optimization to provide energy sharing and additional ancillary services

Renewable energy community represents a new market paradigm adopted to increase the penetration of distributed renewable energy sources and to value the flexibility potentials of customers in presence of behind the meter storage system. Different types of storage systems allow to manage power on different time scale from seconds time basis, f.i. battery, to month, f.i. hydrogen. For this reason, the aggregation of different types of distributed small-scale storage systems may be the solution to maximize the self-consumption of the community and to deliver appropriate ancillary services to the power system. In this context, the paper proposes a day-ahead optimization model for the management of a local energy distributed storage community in order to provide self-consumption benefits and ancillary services to the power system. A detailed analysis with simulation results on a relevant real-life test case are reported and discussed in details.

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.