Hybrid Binders Research Articles

Beneficial effect of green water-soluble binders on SiOx/graphite anode for lithium-ion batteries

The electrochemical performance of SiOx/graphite anode have been improved by using water-soluble binder. When using sodium carboxymethyl (CMC) as binder, the initial Coulombic efficiency, rate capability and charge transfer impedance have been improved. The first discharge specific capacity of SiOx/graphite can reach to 686.2 mAh g−1 when using guar gum (GG) as binder. In addition, various hybrid binders of CMC/GG are investigated to improve the cycle stability and reversible specific capacity synchronously. The results reveal that mixing two water-soluble binders in an appropriate proportion can give play to the respective advantages of the two components.

Technological approaches to increase the quality of lightweight concrete based on hybrid binders

The processes of structure formation of hardening compositions based on hybrid binders as well as the controlled change of these processes allow obtaining concretes with increased strength and durability, for example, lightweight structural concretes on porous aggregates. Control of the structure formation of such concretes allows improving the quality and operational reliability of buildings and structures, saving binders, expanding the kinds of raw materials and solving environmental and economic issues. The results of the experiments have showed that the fineness of the hybrid binder effect the properties of the contact zone between the expanded clay aggregates and the cement matrix including the formation of calcium hydrosilicates on the surface of expanded clay gravel, which increases the adhesive strength. This leads to the increase of the quality of lightweight concrete based on expanded clay gravel.

Effect of industrial by-products incorporated in composites on strength and leaching parameters due to microbiologically induced corrosion

The durability of cement-based materials is an increasingly important characteristic for civil engineering structures due to the growing demand for their long service life and minimal maintenance. Mortars and concrete with high acid resistance are required for the construction and the repair of sewer structures, in which biogenic sulphuric acid attack is the major degradation mechanism. Important progress has been achieved in this regard with hybrid binders and materials known as supplementary cementitious materials (blast furnace slag, silica fume, fly ash etc.). These mainly industrial wastes and by-products increase many important properties of concrete structures such as acid resistance, permeability, strength and many more. This study investigates the effect of industrial by-products such as blast furnace slag and fly ash on strength and leaching parameters of composites exposed to bacterial influence. The medium with bacteria A. thiooxidans was used for microbiologically induced corrosion and the experiments were conducted during the period of 9 months. The sample with 95 wt. % of slag was found more resistible in bacterial environment compared to the sample with hybrid binder.

In-service performance of hybrid geopolymer binders based class F fly ash

Production of high-performance construction materials, meeting the requirements of construction process when development of up-to-date buildings and structures is very relevant and requires the usage of effective polycomponent binding systems, including geopolymers This work studied mechanical performance, as well as strength, water absorption and water resistance of portland cement – Class F fly ash – NaOH hybrid geopolymer binding system. The bench scale testing was conducted on different mixes, including regular portland cement-based and Class F fly ash-NaOH geopolymer binders used as reference compositions. The developed hybrid binders demonstrated, that incorporation of portland cement up to 40% as a modifying agent, reduces the formation of water soluble mineral phases such as sodium carbonates and hydroxycarbonates in low reactive class F fly ash geopolymer binders. It was found, that the presence of portland cement in the system positively affects strength development and noticeably reduces water absorption and improves water resistance of the developed binders, which is related to formation of water resistant and stable calcium hydrosilicate phases (C-S-H)

Insight into the dependence of dirt adsorption/desorption on the surface wetting behavior of TiO2–based nanocomposite coatings

TiO2–based nanocomposite coatings were fabricated using two silicon-oxo hybrid binders and further treated with UV-irradiation to acquire coatings with a wide range of static water contact angles (SWCA) (from 5° to 118.6°) and different dynamic surface wetting behaviors. The dirt adsorption and desorption behavior of these coatings were measured after applying modified rice-straw ash and washing with a water-spray. The results were correlated with static surface wettability and dynamic surface wettability values. It was found that the coatings with an SWCA of about 75° displayed the highest dirt adsorption regardless of the type of binder used. Lower SWCA and receding water contact angles (RWCA) allowed for better dirt desorption and hence better dirt pickup resistance. The coatings with RWCA values close to 0° exhibited self-cleaning performance even when the surface was not superhydrophilic. In addition, the amount of dirt removed from the surface of the coatings by dirt desorption tests was evaluated and used as an indicator of the ability of the coating to remove dirt from polluted air. Specific SWCA and low RWCA values seem to be critical to the coating’s ability to remove dirt from the air. In addition, the dependence of the dirt removal ability on the hysteresis of water contact angle (HWCA) was different for the two silicon-oxo hybrid binders.

Characterization of Dense-Graded Asphalt Containing Virgin, Postconsumer, or Blended Polymer Systems

Abstract This paper contains data related to ground tire rubber (GTR), and binder and mixture performance information is presented that validates some aspects of current practice yet shows that other areas could be improved. While GTR has been utilized in asphalt paving since the 1960s and use in dense-graded mixes began in the late 1980s to early 1990s, proper formulations (including understanding GTR’s functional polymer content) have been lacking a considerable portion of the time. This paper’s primary objective was to review, evaluate, and suggest enhancements to GTR modified binder characterization. One finding was that parallel plate (PP) testing at a 2-mm gap is adequate for binders with 30 mesh (0.595 mm) and finer GTR particles, while cup and bob testing is more suitable for binders with coarser GTR particles. Enhancements were suggested for GTR’s use in modified binder systems related to incorporating hybrid binders containing styrene-butadiene-styrene (SBS) and GTR. Discussion is provided regarding specifying GTR based on virgin polymer replacement.

An overview and experimental study on hybrid binders containing date palm ash, fly ash, OPC and activator composites

Global warming due to high greenhouse gasses emission coupled with excessive energy involved in concrete manufacturing process is indeed an alarming threat. To overcome the problem, numerous researches have been carried out to partially replace ordinary Portland cement (OPC) with supplementary cementitious materials (SCMs) that includes agricultural or industrial solid wastes, development of alternative binder known as geopolymer concrete made of one or more pure SCMs using alkaline activators and elevated temperature curing or by development of hybrid cement system that incorporates alkaline activation of OPC-based SCMs. This study aims to: (1) carry out an overview on: CO2 emission by construction industry; alternate cement systems such as partial replacement, geopolymers and most importantly hybrid binders; as well as identification of date palm ash (DPA) as a potential waste material and (2) develop novel hybrid alkali activated binders with a combination of agro-industrial waste to form binary and ternary mortar binders cured under water up to 28-days. The utilized SCMs include fly ash (FA), ground date palm ash (GDPA) i.e. alkali activated or raw DPA i.e. non-activated. These hybrid and non-hybrid binders were compared through physical properties such as strength and workability along with microstructural properties by hydration products and pore volume. X-ray diffraction (XRD) technique was employed to get the mineral composition; phase decomposition of unreacted water, C-S-H/C-A-S-H gel and Ca(OH)2 had been studied by Thermogravimetric analysis (TGA) while nitrogen adsorption test determined surface area of particles as well as pore volume of the paste. The results revealed potential use of DPA as a strong and sustainable material in ternary blend with FA and OPC in conventional non-hybrid binder that can efficiently maximize clinker replacement without energy utilization in alkaline activation.

Quantification in frame semantics with binders and nominals of hybrid logic

This paper aims to integrate logical operators into frame-based semantics. Frames are semantic graphs that allow lexical meaning to be captured in a fine-grained way but that do not come with a natural way to integrate logical operators such as quantifiers. The approach we propose stems from the observation that modal logic is a powerful tool for describing relational structures, including frames. We use its hybrid logic extension in order to incorporate quantification and thereby allow for inference and reasoning. We integrate our approach into a type theoretic compositional semantics, formulated within Abstract Categorial Grammars. We also show how the key ingredients of hybrid logic, nominals and binders, can be used to model semantic coercion, such as the one induced by the "begin" predicate. In order to illustrate the effectiveness of the proposed syntax-semantics interface, all the examples can be run and tested with the Abstract Categorial Grammar development toolkit.

Rheological characterisation of terminal blend rubberised asphalt binder containing polymeric additive and sulphur

The materials composition has an important effect on rheological properties of Terminal Blend (TB) hybrid asphalt binder. In this study, TB hybrid asphalt binders containing crumb rubber modifier, styrene–butadiene–styrene (SBS) and sulphur at different percentages were prepared. Storage stability test, Superpave performance grading test and multiple stress creep and recovery test, and bending beam rheometer test were conducted to investigate rheological behaviours of TB hybrid binders. Rheological master curve constructed at 25°C was used to characterise the rheological behaviour of TB hybrid binders over wide frequencies. The results indicated that SBS and sulphur help to improve the high-temperature properties and elastic behaviour of TB rubberised asphalt binders, especially when critical sulphur amount is used. The increase in sulphur amount could produce less m-controlled TB hybrid binders. According to the laboratory investigations, 0.2–0.3% amount is recommended to produce TB hybrid binders with reasonable storage stability, allowable viscosity and balanced high-temperature and low-temperature performance.

Hydration of Hybrid Alkaline Cement Containing a Very Large Proportion of Fly Ash: A Descriptive Model.

In hybrid alkaline fly ash cements, a new generation of binders, hydration, is characterized by features found in both ordinary portland cement (OPC) hydration and the alkali activation of fly ash (AAFA). Hybrid alkaline fly ash cements typically have a high fly ash (70 wt % to 80 wt %) and low clinker (20 wt % to 30 wt %) content. The clinker component favors curing at ambient temperature. A hydration mechanism is proposed based on the authors’ research on these hybrid binders over the last five years. The mechanisms for OPC hydration and FA alkaline activation are summarized by way of reference. In hybrid systems, fly ash activity is visible at very early ages, when two types of gel are formed: C–S–H from the OPC and N–A–S–H from the fly ash. In their mutual presence, these gels tend to evolve, respectively, into C–A–S–H and (N,C)–A–S–H. The use of activators with different degrees of alkalinity has a direct impact on reaction kinetics but does not modify the main final products, a mixture of C–A–S–H and (N,C)–A–S–H gels. The proportion of each gel in the mix does, however, depend on the alkalinity generated in the medium.

Chemical activation of hybrid binders based on siliceous fly ash and Portland cement

The hydration of Portland cement (PC) blended with a high amount of a siliceous fly ash (70% fly ash, 30% PC) has been examined. The fly ash contributes significantly to the long-term strength development, when compared to a reference sample with quartz powder. However the long setting time and the poor early strength prevent the use of such binders. Therefore the effect of different activators (sodium carbonate, potassium sodium silicate, potassium citrate and sodium oxalate) on the setting, the hydration kinetics and the strength development of the fly ash-PC blend has been investigated.The addition of the activators increases the pH and decreases thus the calcium concentrations in the pore solution, which leads to a faster reaction of alite and thus to early setting and increased early strength. On the long term, the high alkali concentrations lower the compressive strength and lead to a (partial) destabilization of ettringite.Sodium oxalate and potassium sodium silicate accelerate both the setting of the fly ash-PC blend and increase the early compressive strength. Furthermore, they show better compressive strengths at later ages compared to the other activators. Based on these findings, they can be considered as the most suitable accelerators among the investigated activators.

Fabrication of Al2O3 Coatings on Metal Substrates by Electrophoretic Deposition by the Addition of Polydimethylsiloxane-Based Organic-Inorganic Hybrid Materials as Binders

Polydimethylsiloxane (PDMS)-based organic-inorganic hybrids have been studied because of their high dielectric strength, heat resistivity, and flexibility. In this study, we fabricated Al2O3 coatings on metal substrates with sufficient electrical insulation, heat conductivity, and thermal stability by electrophoretic deposition (EPD) using PDMS-based hybrid binders. The scratch hardness, thermal conductivity, and electrical breakdown strength of the Al2O3 coating before and after heat treatment at 300 °C for 500 h were 2.0 N, 3.1 W/mK, and 60 kV/mm, respectively. These results demonstrate the usefulness of EPD using PDMS-based hybrid binders for fabricating flexible heat dissipative substrates used in high-temperature environments.

Effect of metakaolin substitution on physical, mechanical and hydration process of White Portland cement

In this study characterizations of cementitious composites containing metakaolin were examined via spectroscopic methods (XRD, DTA, TGA, FT-IR and SEM). Hybrid binders were obtained by replacing cement with metakaolin (5, 10, 15, 20, 25 and 30% by weight). In addition to spectroscopic methods, the bending and compressive strengths of the prepared samples were measured at the 2nd, 7th, 28th, 56th and 90th days. In conclusion it was determined that while the metakaolin replacement ratio increases the strength values on the 28th day decrease, yet due to the pozzolanic effect significant increases in strength are obtained on the 56th and 90th days.

Full-Scale Demonstration of a Hybrid Hydrolyzed Collagen-Alkali Silicate Core Binder

A novel core binder system has been devised that is comprised of hydrolyzed collagen and alkali silicates. Cores that employ this hybrid binder were tested in a full-scale demonstration at a partner foundry. Among the 244 iron castings manufactured at this facility while using these hybrid binders, none of the iron castings were rejected as scrap due to core-related defects. The core regions of these iron castings exhibited no deformation, veining, or erosion from molten iron exposure. Moreover, these hybrid silicate-collagen cores demonstrated satisfactory shakeout during full-scale demonstrations. This hydrolyzed collagen-alkali silicate binder yielded cores that achieved a higher tensile strength and less hot distortion than conventional phenolic urethane binders.

Flexible binders, their degradation and impact on cement substrate

Abstract Compared to the traditional inorganic binders based on mortar or plaster, cementing clefts and cracks with polymer fl exible binders is effective in terms of better adhesion and fl exibility. Nevertheless, in order to be applicable in restoration practice they must comply with the condition of a minimum impact on the substrate, which frequently is a porous material. Silicon-based binders, synthetic rubber and hybrid binders based on silicone modifi ed with polyurethane and polyether were tested in this study. The binders were artifi cially aged under various conditions. At the same time, the study also focused on the extent of infl uencing of the porous cement substrate by the application of binders. The silicone binders showed the best resistance to artifi cial aging, however, the originally hydrophilic substrate became hydrophobic. Hybrid binders showed better resistance to moist rather than dry atmosphere. Testing in the QUV panel caused cracking and incoherence of all hybrid bonders. Various categories of binders showed similar properties in terms of resistance to aging and the extent of infl uencing of the porous substrate. The porous cement substrate was reported to be substantially infl uenced by all tested binders. Therefore, none of the tested binders can be unambiguously recommended for application in restoration practice.

Acrylic polyol/silicone coating corrosion protection analysis using electrochemical impedance spectroscopy

Purpose – The purpose of this paper is to develop different combinations of acrylic polyol and silicone resins with various weight ratios and to test the coating properties using electrochemical impedance spectroscopy (EIS). Design/methodology/approach – The performance properties such as coating resistance, capacitance, dielectric constant, water uptake and diffusion coefficient were evaluated using EIS with exposure to 3.5 per cent NaCl solution for 60 days. Findings – The binders developed in this study were coated on cold rolled steel plates. The dry film thickness was found to be in the range of 50 microns. From EIS results, it was found that Acrylic polyol sample with 30 weight per cent of silicone exhibits the best properties, as it has high coating resistance in the range of 109 Ohms for the full period of exposure, whereas all other samples showed poor performance with the exposure time. For these samples, the parameters measured such as the coating resistance of the samples decreased while the coating capacitance, percentage of water uptake and diffusion coefficient of the samples increased after being exposed to corrosive solution for 60 days. The coatings developed by 0, 10 and 60 weight per cent silicone showed high coating capacitance on the first day of exposure, and these systems failed early during the exposure. The water uptake percentage and diffusion coefficient of all samples were found to be less than 50 per cent and below 10-11 cm2 s−1, respectively. An optimum cross-linking between the resins is considered as the main contribution for the best performance shown by the sample that consists of 30 weight per cent of silicone in acrylic matrix that provides maximum barrier properties of the coating. Originality/value – Developing coatings using hybrid binders (silicone resin and acrylic polyol resin) is new area of research. This will explore more research in the formulation of novel coatings.

Hyperbranched β-Cyclodextrin Polymer as an Effective Multidimensional Binder for Silicon Anodes in Lithium Rechargeable Batteries

Polymeric binders play an important role in electrochemical performance of high-capacity silicon (Si) anodes that usually suffer from severe capacity fading due to unparalleled volume change of Si during cycling. In an effort to find efficient polymeric binders that could mitigate such capacity fading, herein, we introduce polymerized β-cyclodextrin (β-CDp) binder for Si nanoparticle anodes. Unlike one-dimensional binders, hyperbranched network structure of β-CDp presents multidimensional hydrogen-bonding interactions with Si particles and therefore offers robust contacts between both components. Even the Si nanoparticles that lost the original contacts with the binder during cycling recover within the multidimensional binder network, thus creating a self-healing effect. Utilizing these advantageous features, β-CDp-based Si electrode shows markedly improved cycling performance compared to those of other well-known binder cases, especially when combined with linear polymers at an appropriate ratio to form hybrid binders.

Hydration kinetics in hybrid binders: Early reaction stages

Activated blends of Portland cement and fly ash with a high ash content (>70%) are a new alternative to traditional OPCs. A number of papers have been published on C–S–H and N–A–S–H, the two gels that constitute the main cementitious products generated by the alkaline activation of these cements, and the elements that may be taken up into their structure. Very little is known about the kinetics of these systems, however, particularly during the early stages of the reaction. The present study used isothermal conduction calorimetry to explore hydration kinetics during the first 72h in a cement containing 30% OPC and 70% fly ash. Two activating solutions were used: a mix of NaOH+Na2SiO3 and a Na2CO3 solution. The findings showed that hydration kinetics were substantially modified by the type of alkaline activator used, particularly with respect to the secondary phases generated. In both cases the main reaction product appeared to be a mix of C–A–S–H and (N,C)–A–S–H gels, whose proportions were clearly impacted by the type of activator used.

Evaluation of the tensile strength of foundry cores made with hybridized binder composed of Neem oil and Nigerian gum arabic.

Defined quantities of the vegetable oil extracted from the seed of Neem tree were mixed with each of four commercial grades of Nigerian gum arabic exudates as hybrid binders for foundry sand cores. The cores which were made with silica sand were classified and oven baked at 200°C for 1 - 3 h, oven cooled and then tested for tensile strength using standard universal strength machine to ascertain their level of suitability for industrial casting. The specimens for tensile strength were shaped like figure eight. The result showed that grade 2 gum arabic hybrids with Neem oil offered best economic advantage as it attained required tensile strength after the shortest period of baking. It was followed by the grade 4, grade 1 and then grade 3 gum arabic based hybrids with Neem oil in that order. The benefit of hybridizing Nigerian gum arabic exudates with Neem oil was more pronounced when cores were baked at about the melting temperature of the grade of gum arabic involved. Baking cores below the melting point marginally improved bond strength while baking them at temperatures well above melting point depressed tensile strength. Key words: Neem oil, gum Arabic, hybrid binder, tensile strength.

Synthesis and performance of alkyd–acrylic hybrid binders

Preparation and properties of alkyd–acrylic hybrids have been studied. Hybrids with different alkyd–acrylic ratios and acrylic parts were prepared via free radical polymerization of acrylic monomers in a presence of an unsaturated alkyd resin using emulsion polymerization technique. The binders were characterized according to their solid content, conversion, viscosity, pH and particle size. Evidence on formation of true copolymer was obtained via NMR spectroscopy and molecular weight and glass transition temperature measurements, as well as via performance studies. The performance evaluation was focused on investigation of drying, penetration and water repellency ability, as well as on film formation and surface topography studies. The binders were compared to references of an alkyd emulsion, acrylic latex and a blend made of them. The results showed that alkyd–acrylic hybrids with synergistic and improved properties can be prepared.