Structure Of Binders Research Articles

Mechanism exploration of the modified asphalt binders with sustainable rapeseed-based derivatives using multi-scale evaluation method

Due to the concerns of sustainability, environment, and economy that are associated with non-renewable petroleum-based additives, there has been a growing interest in bio-additives derived from renewable feedstocks. This study aims to reveal the modification mechanism of three bio-additives derived from rapeseed on the base asphalt. The exploration of modification mechanism helped to explain the distinct rheological properties of bio-modified asphalt binders presented in a previous study. The effect of three bio-additives on the surface morphology, micro-mechanical properties, adhesivity, and chemical structure of base asphalt binders were investigated via Atomic Force Microscopy (AFM) and Fourier Transform Infrared spectrometer (FTIR) tests. The Electrostatic potential distribution and the orbital energy was analyzed via density functional theory (DFT) calculation to explore the inherit polarity of both the three bio-additives and asphalt components. Furthermore, molecular dynamic (MD) methods were used to evaluate the compatibility mechanism and aggregation tendency of asphalt components and bio-additives. The results showed that the electrostatic potential and the orbital energy of three bio-additives predominantly centered around the polar group. Specifically, AERO exhibited highest electrostatic potential distribution and lowest energy gap, indicating its heightened polarity. Moreover, the solution parameter difference value of bio-modified asphalt fell within 0.2 (J/m3)0.5, indicating great compatibility between asphalt and bio-additives, especially for ERO. Additionally, three bio-additives mitigated the aggregation of asphaltene within the asphalt due to their electrostatic interaction, especially notable in the cases of ERO and AERO. Furthermore, a cross-link network was formed within AERO-modified asphalt binders owing to its heightened polarity, fostering hydrogen bonding interactions internally and promoting the aggregation of saturate and resin factions around it. Consequently, this led to enhanced modulus and elasticity in the AERO-modified asphalt binders. Rapeseed derivatives as asphalt additives would be a sustainable and durable material for pavement construction and maintenance. It provides a theoretical basis for advancing the practical application of renewable vegetable oils in road engineering, which has exceptional economic and social benefits.

Towards 3D Pore Structure of Porous Gypsum Cement Pozzolan Ternary Binder by Micro-Computed Tomography

A sophisticated characterisation of a porous material structure has been challenging in material science. Three-dimensional (3D) structure analysis allows the evaluation of a material’s homogeneity, pore size distribution and pore wall properties. Micro-computed tomography (micro-CT) offers a non-destructive test method for material evaluation. This paper characterises a novel ternary binder’s porous structure using micro-CT. Gypsum–cement–pozzolan (GCP) ternary binders are low-carbon footprint binders. Both natural and industrial gypsum were evaluated as a major components of GCP binders. Porous GCP binder was obtained by a foaming admixture, and the bulk density of the material characterised ranged from 387 to 700 kg/m3. Micro-CT results indicate that pores in the range from 0.017 to 3.0 mm can be effectively detected and described for porous GCP binders. The GCP binder structure proved to be dominant by 0.1 to 0.2 mm micropores. For GCP binders produced with natural gypsum, macropores from 2.2 to 2.9 mm are formed, while GCP binders with phosphogypsum possess pores from 0.2 to 0.6 mm. Micro-CT proved to be an effective instrument for characterising the homogeneity and hierarchical pore structure of porous ternary binders.

Investigation of Surface Modification of Bagasse Fibers: Performance of Asphalt Binders/Mixtures with Bagasse Fibers

The influence of surface modification on the properties of bagasse fibers and asphalt binders/mixtures was investigated. Bagasse fibers were modified by single, binary, and ternary methods with hydrochloric acid, sodium hydroxide, and sodium chlorite, respectively. The physical and chemical properties of bagasse fibers were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, and an adsorption test, respectively. The rheological properties of asphalt binders with bagasse fibers or lignin fibers were analyzed by the dynamic shear rheometer test and bending beam rheometer test. In addition, the performance of asphalt mixtures with bagasse fibers or lignin fibers were evaluated by a wheel rutting test, bending test at a low temperature, and water stability test, respectively. In conclusion, the hydrophilic functional groups on the fiber surface were partially eliminated by modification, facilitating the degradation of different fiber components. Furthermore, the degree of fibrillation was improved, and more interfaces with asphalt components were formed, thus enhancing the high-temperature deformation resistance of asphalt binders, but slightly impairing its low-temperature performance. Among all modification methods, the ternary composite modification exerted important influences on fiber structure, oil absorption, and rheological properties of asphalt binders, significantly enhancing the performance of asphalt mixtures. Combined with surface modification methods, bagasse fibers would be promising reinforced pavement materials.

Comparison of the Structure and Thermal Properties of Energetic Binders for Application in Propulsion

Comparison of the Structure and Thermal Properties of Energetic Binders for Application in Propulsion

Carbonate binders: Historic developments and perspectives

This paper reviews the historic developments and provides some perspectives of carbonate binders. Various carbonatable materials have been used to produce carbonate binders using different carbonation techniques. The carbonate binders are mainly composed of calcium/magnesium carbonate and silica/alumina gels. Three crystalline polymorphs, namely calcite, aragonite and vaterite can be formed. The properties of carbonate binders are strongly affected by the crystalline polymorphs and also the polymerization degree of amorphous silica gel. During the past 4 years, physical, chemical and biological methods have been proposed to control the polymorphous of calcium carbonate. Some industrial demonstration and applications have already been successfully implemented. The production and application of carbonate binders can use up to several hundred million tons of CO2. However, there is an urgent need to increase the carbonation degree and to regulate the composition and structure of carbonate binders so to achieve better performance of carbonated construction products.

Bitumen improvement with bio-oil and natural or organomodified montmorillonite: Structure, rheology, and adhesion of composite asphalt binders

The use of nanoscale particles and modifiers from renewable raw materials are modern approaches to improving the properties of existing materials. This paper examines the combined application of montmorillonite nanoparticles (10–30%) and bio-oil (5–20%) to improve the properties of bitumen binder. A study of the rheological and wetting properties of bitumen has shown that the addition of 10% bio-oil alone maximizes the adhesion of bitumen to silicate surface without a noticeable deterioration in the fluidity of its melt. Due to bitumen’s hydrophobicity and bio-oil’s hydrophilicity, montmorillonite was considered in two variants: hydrophilic (natural) and hydrophobic (organomodified). Hydrophilic particles form submillimeter aggregates in the bitumen medium, reduce its viscosity at low content and high temperatures, and shift the solid–liquid transition point towards lower temperatures. In addition, these particles increase the bitumen’s stiffness upon cooling, its cohesion and adhesion, but slightly worsen the low-frequency elasticity. Hydrophobic clay affects the bitumen’s properties more strongly, which is due to its exfoliation to nanoscale particles. This clay causes the gelling of bitumen binder at high concentrations over a wide temperature range, significantly improving its elasticity, stiffness, cohesion, and adhesion. Hydrophobic particles are better suited to produce a high-quality binder but make it highly viscous.

Rheological, chemical and short-term aging properties of waste polyurethane particles modified asphalt binder with or without SBS

In order to effectively dispose of waste polyurethane (WPU) and obtain modified asphalt binders with excellent properties, WPU particles are used to modify asphalt binder. Conventional properties and thermal storage stability of asphalt binders are analyzed, their rheological properties and creep recovery properties are tested by the dynamic shear rheological (DSR). Microstructure, molecular weight and chemical structure of the asphalt binders are analyzed by fluorescence microscopy (FM), gel permeation chromatography (GPC) and fourier transform infrared spectroscopy (FTIR) respectively. Results show that low temperature crack resistance of base asphalt binder is improved due to WPU particles addition, which impairs the property of SBS modified asphalt binder. After short-term aging, the Jnr at 3.2 kPa (Jnr3.2) of modified asphalt binder with WPU particles is less than 2.0 kPa−1. And Jnr3.2 of base asphalt binder decreases by 52.4 % due to WPU particles addition, it is 25.5 % for SBS modified asphalt binder. The thermal storage stability of WPU particles modified asphalt binder is poor and improved by 42.3 % due to the SBS use. The rod-shaped WPU particles are found in modified asphalt binder without SBS, and their structure is destroyed during aging, forming numerous small particles and small molecular products, which improve rutting resistance of asphalt binder. When aged at 150 °C, 163 °C and 180 °C, addition of WPU particles makes aging resistance of base asphalt binder increase by 0.9 %, 1.5 % and 1.2 % respectively, which impairs the aging resistance of SBS modified asphalt binder by 0.9 %, 5 % and 5.3 % respectively. FTIR results manifest decomposition reaction presented in WPU during preparation and aging, forming products with CO.

Molecular dynamics simulation on the rejuvenation effects of waste cooking oil on aged asphalt binder

Waste cooking oil (WCO) has received attention on rejuvenating aged asphalt binder widely in recent years. This study evaluated the rejuvenation effects of WCO on aged asphalt binder on the micro-scale using molecular dynamics (MD) simulation. First, the representative molecules of WCO and asphalt binders were selected. The molecular mixture model was then developed. The thermodynamic properties were investigated, including density, cohesive energy density, solubility parameter, and surface free energy. The results show that WCO can restore the thermodynamic properties of aged asphalt binder to some extent and WCO has different influences on electrostatic interactions and van der Waals effects. From the diffusion behavior and molecular structure of asphalt binder, WCO can improve the molecular mobility and restore the colloidal structure. Besides, the adhesion work and moisture susceptibility of asphalt binder-aggregate interfaces (calcite and quartz) were evaluated. The results show that WCO can improve adhesion work between asphalt binder and aggregates since WCO can change molecular structure of asphalt binders and certain adhesion work exists between WCO and aggregates. Also, it can mitigate the moisture susceptibility of asphalt binder-aggregate interfaces (calcite and quartz). The study demonstrates that the MD simulation can help to understand the rejuvenation effects of WCO on aged asphalt binder on the micro-scale. • WCO can improve the mobility of the saturates best of aged asphalt binder. • WCO can weaken both the self-aggregation of asphaltenes and interactions between asphaltenes and saturates. • WCO can change the molecular structure of asphalt binders.

Mechanical and durability characteristics of GGBS-based self-healing geopolymer mortar produced using by an endospore-forming bacterium

Healing process of the gaps and cracks in the structure of geopolymer binders, which have emerged as greener alternatives compared to their traditional Portland cement counterparts, is of great importance in terms of a long economic life. The application of the microbial induced carbonate precipitation (MICP) method, which is the most striking of the various healing techniques applied to building materials, on geopolymer composites has been limited to a few successful studies. At this point, it is considered to be an important step to examine the effects of addition of bacteria on the mechanical and durability characteristics of geopolymer composites in detail. Therefore, this paper was designed to examine the effect of the usage of Bacillus subtilis on the mechanical and durability performance of ground blast furnace slag (GBFS)-based geopolymer mortar (GPM) specimens. In the GPM specimens activated with Na2SiO3, the total liquid/binder ratio as 0.55 and the binder/fine aggregate ratio as 1:2 was kept constant. Bacterial cultures in liquid form prepared at different concentrations (109 and 107 CFU/mL) were added directly to the Na2SiO3 at 0, 1, 2 and 3% by weight of GBFS. GPM samples, which were prepared in seven different groups in total, were kept in three different curing mediums (precipitation medium, water and ambient conditions) from 7th day to the 28th day. After the curing period was over, the compressive strength, electrical resistivity, sulfate and acid resistance, capillary water absorption, splitting tensile strength and permeability properties were investigated on the GPM samples. In addition, the above-mentioned test results were confirmed by the microstructural analyzes performed. Experimental findings revealed that the optimum bacterial concentration and bacterial dosage values were 107 CFU/mL and 3%, respectively, in terms of both mechanical properties and durability performances. On the other hand, it was observed that all of the GPM specimens cured in precipitation medium (PM) and produced using bacteria had superior performances compared to their counterparts cured in water and ambient conditions. This situation clearly demonstrated that an effective self-healing process that will occur in GPM samples produced with the addition of bacteria directly could only be possible by creating a curing environment containing urea and calcium.

Engineering Pore Network Structure of Binders for Improved Catalytic Performance of Zeolite Pellets Using a Multiscale Model

Engineering Pore Network Structure of Binders for Improved Catalytic Performance of Zeolite Pellets Using a Multiscale Model

Optical and Electronic Microscope for Minero-Petrographic and Microchemical Studies of Lime Binders of Ancient Mortars

In this paper, the advances in the use of optical and electronic microscope for study of the minero-petrographic and microchemical features of lime binders of ancient mortars are discussed for various case studies. Mortars belonging to several historic periods and with different functions in building structures and archaeological sites were selected in order to verify the complementarity of optical and electronic microscope analyses applied to these artificial materials. The data obtained with the application of optical and microscope analyses were able to provide detailed and more precise information on the composition, structure, and texture of lime binders, highlighting the features of air hardening calcitic lime binder, air hardening magnesian lime binder, natural hydraulic lime binder, and air hardening binders with materials providing hydraulic characteristics added. Furthermore, a complete analysis and classification of the lime lumps was determined.

Four-component high-strength polymineral binders

The use of composite binders instead of cement with the use of highly effective types of mineral raw materials, which has gone through the path of multi-stage natural activation due to deep geological processes, is a promising direction of modern construction materials science. The paper is devoted to the development of a resource-saving technology for obtaining high-strength composite binders for energy-efficient construction. The significance of this study is to focus on expanding the raw material base of polymineral binders at the expense of technogenic and substandard materials. The work is aimed at studying the nature of the joint interaction of alumina, silicate and carbonate components from natural and technogenic raw materials, taking into account its genesis in the processes of structure formation of multicomponent hardening systems. The novelty of the work lies in the establishment of regularities for the regulation of the structure and properties of the composite binders with powdered mineral modifiers. Comprehensive researches of natural raw materials included the study of its energy performance and particle sizes parameters after grinding. The synthesized polymineral binders were compared in terms of heat of hydration, rheological and physical–mechanical properties, as well as their microstructure. The developed modified cementitious pastes have a water-binding ratio of no more than 0.3; compressive strength of 81 MPa, flexural strength of 12 MPa. Accordingly, the cement composites have great potential for use in civil engineering.

Coarse grained modeling of nanostructure and asphaltene aggregation in asphalt binder using dissipative particle dynamics

This study aims to develop coarse grained models of asphalt binders and study nanostructure and aggregation behavior of asphalt binders using Dissipative Particle Dynamics (DPD). The coarse-grained models of asphalt binders with different SARA (asphaltene, aromatic, resin and saturate) fractions were built with the mapping of bead groups and the calculation of forcefield parameters. The simulation results were validated through the calculated molecular structure parameters including interlayer distance and diffusion coefficient of asphaltene. The ordered stacking structures (T shape, face–face, and offset face–face stacking) were observed and the aggregation patterns of asphaltene was more obvious between the same type of asphaltene molecules due to self-similarity. The aggregation rates of asphaltene of three asphalt binders were found positively correlated with the mass fractions of asphaltene, which can be used to better predict relative viscosity of asphalt binders. The colloid structure of coarse-grained asphalt binders was observed on the mesoscale platform with small variations of localized nanostructure in three asphalt models. On the other hand, asphaltene showed the lowest diffusion coefficient that was similar among different asphalt binders. The analysis findings indicated that coarse grained modeling with DPD enables large-size model asphalt systems for observation of morphology and aggregation of asphaltene, providing foundation to study complex molecular interaction in polymer modified asphalt binder.

Use of Linear Viscoelastic Functions to Estimate the Aging Resistance and Internal Structure of Bituminous Binders

Rheology is the most widely used technique to evaluate the performance and aging of bituminous binders. Since there are many available rheological tests, there is also a wide range of aging indexes and it is not easy to choose the most appropriate one, because a single value may hardly be adequate for different properties or operating conditions. In order to generalize the usefulness of an index, a good starting point is deriving it from a set of data, such as the master curves of linear viscoelastic functions. Then, the problem is the quantification of aging in a single numerical value from continuous curves, covering a wide range of frequencies/temperatures. In this work, a summary of the aging indexes derived from the master curves is reported and discussed. The indexes are applied to a bituminous binder either with or without the addition of an organo-modified layered silicate. The apparent molecular weight distributions and relaxation spectra were also calculated from the master curves and used to characterize the effect of aging on the binder properties and structure. In this way, an interesting parallelism was observed between the SARA fractions and the populations derived from a deconvolution analysis of the apparent molecular weight distributions.

Generating aptamers towards human sperm cells using massively parallel sequencing

Determining the presence of sperm cells on an item or swab is often a crucial component of sexual offence investigation. However, traditional histological staining techniques used for the morphological identification of spermatozoa lack both specificity and sensitivity, making analysis a complex and time-consuming process. New methods for the detection of sperm cells based on aptamer recognition may be able to overcome these issues. In this work, we present the selection of ssDNA aptamers against human sperm cells using Cell-SELEX and massively parallel sequencing technologies. A total of 14 rounds of selection were performed following a modified Cell-SELEX protocol, which included additional steps for the isolation of spermatozoa from seminal fluid. Massively parallel sequencing using the Illumina Miseq platform was conducted on enriched aptamer pools to elucidate the structure of potential binders. A custom bioinformatics pipeline was also developed using Galaxy for the automated processing of sequencing datasets. This data revealed several promising aptamer candidates, which were shown to selectively bind sperm cells through both microscale thermophoresis and enzyme-linked oligonucleotide assays. These aptamers have the potential to increase the efficiency of sexual offence casework by facilitating sperm detection.Graphical abstract

Impact of the molecular structure of cationic binders on the rheological and adhesive properties of carboxymethyl cellulose-based coacervate hydrogels

Impact of the molecular structure of cationic binders on the rheological and adhesive properties of carboxymethyl cellulose-based coacervate hydrogels

Influence of hard segment content and soft segment length on the microphase structure and mechanical performance of polyurethane-based polymer concrete

Understanding the structure–property relationship of polyurethane (PU) binders is of critical importance in the construction engineering applications. A series of rapid room temperature-curable PU binders were prepared using polyoxypropylene glycol as the soft segments, along with polymethylene polyphenylene isocyanate and 4,4′-methylene-bis(2-chlorobenzenamine) as the hard segments. This work investigated the influence of the hard segment content (40 wt%, 45 wt%, and 50 wt%) and the soft segment molecular weight (1000 g/mol, 2000 g/mol, 3000 g/mol, and 4000 g/mol) on the microphase structure of the PU binders. Their influence on the compressive behaviors, flexural behaviors, impact strengths, and slant shear strengths of the PU-based polymer concretes was also investigated. Structural characterization revealed that increasing either the hard segment content or the larger soft segment molecular weight effectively enhanced hydrogen bonding as well as microphase separation. Our results also demonstrated that a higher hard segment content resulted in better mechanical performance and shorter pot life. In addition, the PU-based polymer concrete using 2000 g/mol polyoxypropylene glycol reached optimal mechanical performance when the hard segment was held constant. Hence, varying the hard segment content and soft segment length can be an effective method to adjust the engineering performance of PU-based polymer concrete.

Effects of Aging on Physicomechanical and Chemical Properties of Chemically Modified Binders

Abstract Asphalt binders and their chemical compositions vary widely based on their crude sources. Chemical modifications are often implemented to attain certain rheological and chemical superiorities over neat (unmodified) binders. These modifications involve complex chemistries. The crude specific behavior of asphalt binders keeps pavement professionals from perceiving the underlying concept of binder modifications. This study was intended to predict the effects of aging on physicomechanical and chemical properties of chemically modified asphalt binders and thereby determine the dosages that would yield optimal benefits of chemical modifications. Asphalt binders from two crude sources (Canadian and Arabian) were primarily modified with Polyphosphoric Acid (PPA). A commonly used polymer, styrene butadiene styrene, was also investigated to compare the results of PPA-modified binders. These binders were analyzed using a column chromatography technique to observe any significant changes in chemical fractions (saturates, aromatics, resins, and asphaltenes) along with colloidal stability. One of the crude sources was also evaluated after its modification with different percentages of a Reclaimed Asphalt Pavement (RAP) binder containing PPA. There were two different optimum levels of chemical modification for two different crude binders. Binders were tested at unaged, short-term, and long-term aging conditions in the laboratory. Two binders demonstrated two different patterns of aging escalation; the Arabian crude binder was found to be more colloidally stable that the Canadian crude binder. Finally, an effort was made to find any correlation between selected physicomechanical properties and chemical compositions of the tested asphalt binders. Some of the mechanical properties were found to be linearly correlated with binders’ chemical compositions. A high amount (over 40 %) of RAP binder modification in neat binders induced some instability in the colloidal structure of the Canadian crude binders.

Development of bio-based stabilizers and their effects on the performance of SBS-modified asphalt

Polymer-modified asphalt has been widely used in pavement engineering thanks to its excellent road performance. However, differences in the molecular structure, molecular weight, and density of polymer modifiers and base asphalt binders make modified asphalts prone to phase separate into the modifier and the base asphalt binder during static processes, such as transportation and storage. To ensure the storage stability of polymer-modified asphalt, stabilizers are usually added in the polymer-modified asphalt preparation process. Sulfur powder is a commonly used stabilizer with a good stabilizing effect for the preparation of modified asphalt but faces the problems of fire hazard and environmental pollution. In this study, based on the compounding process, three environmentally friendly and safe bio-based sulfur stabilizers were developed. Based on the preparation and performance evaluation of styrene-butadienestyrene block copolymer–modified asphalt under the same conditions, the effects of bio-based stabilizers on the performance of the modified asphalt were investigated. A comparative evaluation of the physical properties of modified asphalts was used to infer the high-temperature performance from the rutting factor measured by a dynamic shear rheological test. The low-temperature performance was inferred from the stiffness S and the m value measured by the bending beam rheological test. The elastic recovery performance of asphalt was characterized in terms of the average percent recovery R and the nonrecoverable creep compliance Jnr, as measured by a multiple stress creep recovery test. The microscopic morphology of the modified asphalt was observed under a fluorescence microscope. The results showed that the modified asphalts prepared with bio-based stabilizers all had low 135 °C viscosity and good high- and low-temperature performance. The best rheological parameters were found for modified asphalt prepared with Stabilizer A, followed by that prepared with Stabilizer C and then Stabilizer B. Both the original and the short-term-aged modified asphalt containing Stabilizer A showed good network structure under the fluorescence microscope. In addition, the costs of bio-based stabilizers were similar to that of traditional sulfur powder.

The Latest Research Progress of New Self‐Repairing Energetic Composites†

This review summarizes research progress in self‐repairing energetic composites based on the design of chemical structure of binders and the introduction of self‐repairing properties between composite interfaces. Researchers have prepared the polyurethane‐urea binder and the GAP self‐repairing binder based on the disulfide bond, the polyurethane binder and FTPB‐PDMI binder based on the Diels‐Alder reaction, and the polyurethane binder based on dynamic photocrosslinking reaction. In addition, PVDF‐co‐HFP/EMIOTf/graphene achieves the self‐repairing behavior of the polymer bonded explosive (PBX). The future development of self‐repairing energetic composites is proposed. It is pointed out that the mechanical properties, processing properties and energy properties should be improved together with the introduction of self‐repairing properties, and the energetic composites which can be repaired in various ways should be prepared.