Adhesion Of Aggregates Research Articles

Blood-brain barrier permeable carbon nano-assemblies for amyloid-β clearance and neurotoxic attenuation

Abnormal amyloid β-protein (Aβ42) fibrillation is a key event in Alzheimer's disease (AD), and photodynamic therapy (PDT) possesses great potential in modulating Aβ42 self-assembly. However, the poor blood-brain barrier (BBB) penetration, low biocompatibility, and limited tissue penetration depth of existing photosensitizers limit the progress of photo-oxidation strategies. In this paper, novel indocyanine green-modified graphene quantum dot nano-assemblies (NBGQDs-ICGs) were synthesized based on a molecular assembly strategy of electrostatic interactions for PDT inhibition of Aβ42 self-assembly process and decomposition of preformed fibrils under near-infrared light. Combining the small-size structure of graphene quantum dots and the near-infrared light-responsive properties of ICGs, the NBGQDs-ICGs could achieve BBB penetration under 808 nm irradiation. More importantly, the neuroprotective mechanism of NBGQDs-ICG was studied for the first time by AFM, which effectively weakened the adhesion of Aβ42 aggregates to the cell surface by blocking the interaction between Aβ42 and the cell membrane, and restored the mechanical stability and adhesion of the neuron membrane. Meanwhile, NBGQDs-ICG promoted phagocytosis of Aβ42 by microglia. In addition, the good biocompatibility and stability ensured the biosafety of NBGQDs-ICG in future clinical applications. We anticipate that such multifunctional nanocomponents may provide promising avenues for the development of novel AD inhibitors.

Proposition of an aggregate-binder interface index based on the adhesiveness test assessed by digital image processing

Aggregate-binder adhesiveness impacts asphalt mixture performance. Evaluation of this interface within mixes typically involves visual assessment and digital image processing (DIP), often resulting in an average value for this complex property. Current computational simulations overlook the possibility of incomplete aggregate adhesion to the binder, a common occurrence in cases of adhesive/cohesive failure between materials. This study proposes an interface index determined from adhesiveness test results in order to improve computational simulations. For this purpose, twelve adhesiveness tests, following Brazilian standards, including mineral and steel-slag aggregates, and neat and modified binders, were conducted. Software with a graphical user interface (GUI) was developed to quantify the percentage of aggregate area coated by binder (%Coated) post-testing. Descriptive statistics and probability distributions were applied to %Coated values, in addition to the quality of measurements using DIP. The DIP values exhibited sensitivity across all examined covering scenarios, with statistical tests suggesting a high likelihood of accurately representing the %Coated parameter from the assessed probability distributions. In conclusion, the developed software enables satisfactory quantification of %Coated. Furthermore, this study indicates that the adhesion test results must be represented considering the data variability, with the Beta distribution being a good way to represent the behavior.

Interfacial adhesion features of high-viscosity asphalt and aggregate under water conditioning: Micro perspective and molecular simulation

Interface properties between asphalt and aggregate intimately affect the service performance and long-term durability of asphalt pavement. This study seeks to explore the interfacial adhesion features of high-viscosity asphalt (HVA)-aggregate under water conditioning to provide the understanding for the moisture damage of HVA-aggregate interface and asphalt pavement. To this end, the HVA was initially suffered from different durations of water conditioning, and atomic force microscopy (AFM) test was employed to gather the microscopic phase structure and adhesion force of water-conditioned HVA and aggregate, to analyze the adhesion variations of HVA-aggregate interface. Further, molecular dynamics method was used to simulate the changing process and influencing mechanism of adhesion effect at the HVA-aggregate interface under water immersion. The findings indicated that with the increasing water immersion, Catana phase of HVAs vanished, and concave and convex structures appeared on the surface, along with pit groove dispersion phase structures. Longer immersion time resulted in augmented surface roughness of HVA and a more dispersed height distribution in the area domain, most notably during the initial stages of water immersion. Aging increased sensitivity to immersion duration in terms of surface roughness, mechanical properties and adhesion ability of HVAs. Water immersion had a diminishing effect on the mechanical properties of HVA at different aging degrees, although it increased the micro-mechanical modulus of HVAs and impaired the interface adhesion with aggregates. Under water immersion, the phase structure and mechanical properties of HVAs and the interface adhesion indexes all distinguished a prominent negative Pearson correlation (correlation coefficient |R| > 0.7000), and these factors were critical for HVA-aggregate interface adhesion, as alterations in surface phase structure and micro-mechanical traits of HVAs triggered variations in the HVA-aggregate interface adhesion. In addition, water content in the interface layer, simulation temperature and mineral anisotropy significantly affected the interfacial adhesion of HVA and aggregate in water environment. The introduction of water and the rise of temperature considerably weakened the interfacial adhesion effect of asphalt-aggregate system, and the interface adhesion failure occurred once the water layer thickness surpassed 5 Å. Comparatively, the HVA-calcite system demonstrated better interfacial adhesion competence than the HVA-α-quartz system, and the HVA-calcite {1 0 4} system showed the optimal interfacial adhesion.

Variation of SARA fractions of crumb rubber modified asphalt binder-aggregate interface system and its correlation with adhesion properties

The incorporation of rubber powder leads to a high degree of complexity in the CRMA binder-aggregate interfacial properties, which directly affects the interfacial adhesion performance. The objective of this study is to investigate the variation of SARA fractions of CRMA binder during the adhesion process and to explore the intrinsic relationship between the components and the adhesion properties. To this end, the staged extraction tests were performed to extract CRMA binder layers on the aggregate surface. After each extraction, the binder layer was evaluated in terms of its SARA fraction contents and molecular weight distribution. Additionally, the pull-off tensile strength (POTS) was used to assess the adhesion of the binder-aggregate interface through the binder bond strength (BBS) test. Finally, the correlation between the SARA fractions of CRMA binder and interface adhesion of CRMA binder-aggregate system was analyzed. The results showed that the CR tends to absorb the lighter components of base asphalt, the variations in SARA fractions and molecular weight distribution during the aggregate adhesion to CRMA binders occurred mainly in the third and fourth elution layers. Pen 70 CRMA binder and limestone show the best adhesion properties among all the binder and aggregate types. The increase in CR size and the decrease in CR dosage are favorable for the adhesion of CRMA binders to aggregates. Furthermore, asphaltenes and resins are positively correlated with adhesion, while aromatics and saturants are negatively correlated with adhesion. The correlation between SARA content and adhesion varied depending on the aggregate type.

Influence of Hematocrit Level and Integrin αIIbβIII Function on vWF-Mediated Platelet Adhesion and Shear-Induced Platelet Aggregation in a Sudden Expansion.

Shear-mediated thrombosis is a clinically relevant phenomenon that underlies excessive arterial thrombosis and device-induced thrombosis. Red blood cells are known to mechanically contribute to physiological hemostasis through margination of platelets and vWF, facilitating the unfurling of vWF multimers, and increasing the fraction of thrombus-contacting platelets. Shear also plays a role in this phenomenon, increasing both the degree of margination and the near-wall forces experienced by vWF and platelets leading to unfurling and activation. Despite this, the contribution of red blood cells in shear-induced platelet aggregation has not been fully investigated-specifically the effect of elevated hematocrit has not yet been demonstrated. Here, a microfluidic model of a sudden expansion is presented as a platform for investigating platelet adhesion at hematocrits ranging from 0 to 60% and shear rates ranging from 1000 to 10,000 s-1. The sudden expansion geometry models nonphysiological flow separation characteristic to mechanical circulatory support devices, and the validatory framework of the FDA benchmark nozzle. PDMS microchannels were fabricated and coated with human collagen. Platelets were fluorescently tagged, and blood was reconstituted at variable hematocrit prior to perfusion experiments. Integrin function of selected blood samples was inhibited by a blocking antibody, and platelet adhesion and aggregation over the course of perfusion was monitored. Increasing shear rates at physiological and elevated hematocrit levels facilitate robust platelet adhesion and formation of large aggregates. Shear-induced platelet aggregation is demonstrated to be dependent on both αIIbβIII function and the presence of red blood cells. Inhibition of αIIbβIII results in an 86.4% reduction in overall platelet adhesion and an 85.7% reduction in thrombus size at 20-60% hematocrit. Hematocrit levels of 20% are inadequate for effective platelet margination and subsequent vWF tethering, resulting in notable decreases in platelet adhesion at 5000 and 10,000 s-1 compared to 40% and 60%. Inhibition of αIIbβIII triggered dramatic reductions in overall thrombus coverage and large aggregate formation. Stability of platelets tethered by vWF are demonstrated to be αIIbβIII-dependent, as adhesion of single platelets treated with A2A9, an anti-αIIbβIII blocking antibody, is transient and did not lead to sustained thrombus formation. This study highlights driving factors in vWF-mediated platelet adhesion that are relevant to clinical suppression of shear-induced thrombosis and in vitro assays of platelet adhesion. Primarily, increasing hematocrit promotes platelet margination, permitting shear-induced platelet aggregation through αIIbβIII-mediated adhesion at supraphysiological shear rates. The online version contains supplementary material available at 10.1007/s12195-024-00796-0.

Effect of aging on the low-temperature performance of fiber-reinforced asphalt mixtures

To study the effect of aging on the low-temperature crack resistance of fiber asphalt mixes, three kinds of fibers (lignin fiber, polyester fiber, and basalt fiber) were dry blended into AC-13 asphalt mixes to prepare unaged, asphalt aged (that is, the original asphalt material is subjected to aging treatment), short-term aged, and long-term aged fiber reinforced asphalt mixes. Semicircular bending (SCB) tests and scanning electron microscopy tests were used to analyze and study the effects of aging time and fiber type on the low-temperature properties of asphalt mixtures at an ambient temperature of −5 °C. The SCB test results indicated that: with the deepening of aging, the fracture toughness and fracture energy of the fiber asphalt mixture specimens will tend to decrease, and the aging of the original asphalt has a greater impact on the specimens without fiber; there was great variability in the effect of lignin fibers on the crack resistance of the mix, but it could be a good promoter in unaged asphalt mixes; polyester fiber is the material of choice for improving low-temperature crack resistance in long-term aging pavements; the incorporation of basalt fiber greatly enhances the crack resistance of asphalt mixes and is an excellent material for improving aging asphalt mixes. It is clearly seen by the scanning electron microscope test that with the deepening of aging, the adhesion of asphalt and aggregate gradually deteriorates, and even more so, there is the phenomenon of fine aggregate flaking, and the fiber cannot play an excellent role in reinforcement and crack resistance.

Effect of thickness on the behavior of aggregate-asphalt-aggregate film subjected to dynamic shearing and uniaxial tension

Although the asphalt-aggregate interface and its film thickness present important effect on performance of asphalt mixtures, there are no effective methods to accurately evaluate those factors. This study focuses on the effect of aggregate-asphalt-aggregate thickness on the shearing and tension mechanical properties of the asphalt-aggregate by using aggregate developed Dynamic Shearing Rheometer (DSR). Utilizing microscopic techniques to observe the surface morphology of different aggregates and the adhesion state of asphalt-aggregate micro-interface zone, and then carried out the dynamic shear rheological test and uniaxial tension test analysis of aggregate-asphalt-aggregate system under different interlayer thickness and different aggregate adhesion conditions. Results indicate that the developed DSR using aggregate plates is a helpful device to simulate the interface in asphalt mixtures. Differences in microscopic morphology and chemical adhesion have a significant impact on the shearing and tension behavior of aggregate-asphalt-aggregate system. The influence of microscopic interaction between aggregate and asphalt on the mechanical behavior of asphalt is dependent on temperature, frequency, interlayer thickness, and loading pattern. The thickness of the interlayer shows different modes subjected to loading, which is reflected as that film thinning means modulus softening during shearing loading and film thinning means modulus strengthening during tension loading.

Motive Characteristics and Adhesion-Rebound Mechanism of Single Aggregate Based on Shotcrete

The theory of viscoelastic collision mechanics is used to explore the rebound and adhesion mechanisms of single aggregates in shotcrete at the meso-level in this study. Abrasive balls with different radiuses were used, fully considering the characteristics of the aggregates and the sprayed wall, to build multifactor physical models for the shotcrete rebound of the aggregate. The movement trajectories, velocities, and energy dissipations of abrasive balls are analyzed, and the shotcrete-rebound mechanical model of a single aggregate based on wet-mix shotcrete is proposed. The results of the study show that there are obvious differences in the rebound velocity of the aggregate in different collision forms, and the viscoelastic properties of aggregates affect the jet stability of wet-mix shotcrete. According to the quantitative and qualitative analyses, the energy loss during the collision-rebound of the aggregate is inversely proportional to the rebound velocity and proportional to the rebound resistance. The functional relationship between the resistance F and the particle radius R during the rebound and adhesion of aggregate can be expressed as F=CR1/5, where C is a constant.

The Effect of Wetfix and Nanohydrated Lime Additives on Bitumen Aging and the Cohesion and Adhesion Failure Mechanisms of Hot Asphalt Mixtures

Aging due to sunlight and the passage of time is an effective element in the occurrence of moisture damage in hot asphalt mixtures. Still, the effects of this parameter are scarcely considered in the experiments examining the moisture damage potential. Accordingly, this study investigated the effect of aging on the performance of hot asphalt mixtures and examined the improvement of moisture damage performance by using antistripping additives via mechanism and functional tests. Two types of aggregates (limestone and granite) with different degrees of moisture sensitivity, two types of bitumen (PG64-16 and PG58-22) with different performances, and two additives (Wetfix liquid additive and nanohydrated lime) as bitumen modifiers were used. Bitumen samples and asphalt mixtures were subjected to short- and long-term aging. The pull-off test was performed to explore the aging effect on different failure mechanisms (cohesion and adhesion), and the indirect tensile stiffness modulus (ITSM) test was conducted to study the asphalt mixture’s performance against moisture damage. The results specify that aging, in terms of hot asphalt mixture hardening in dry and wet conditions, decreased the MSR (resilient modulus wet to resilient modulus dry ratio), and this decline was greater in long-term aging. The pull-off test results exhibited that aging, especially in the long term, decreased the asphalt mixture’s adhesive strength in dry and wet conditions; this decline in adhesion was greater in the wet than in the dry state, and this difference decreased the wet-to-dry adhesion strength ratio (the pull-off ratio). The additives relatively improved the yield modulus of the asphalt mixture, but their effect was greater in the wet state. A comparison of the pull-off test results in cohesion and adhesion failure demonstrated that Wetfix was more effective in improving bitumen–aggregate adhesion, whereas nanohydrated lime was more effective in enhancing bitumen adhesion. The resilient modulus (Mr) ratio in wet-to-dry conditions indicated that nanohydrated lime had better effects on the overall performance of the aged asphalt mixture against moisture damage. To investigate the effect of additives on the performance of asphalt mixtures, a t-test was performed in all modes of control, short-term aging, and long-term aging. The findings showed the effect of Wetfix and nanohydrated lime on increasing the modulus of elasticity of the samples.

Study of Factors Influencing Moisture Susceptibility of Warm-Mix Asphalt Using the Surface Free Energy Approach.

The application of warm-mixing technology brings considerable economical and environment benefits by decreasing the mixing temperature during warm asphalt mixture (WMA) production. However, the possible water residue also generates concerns for moisture susceptibility. For deep investigation on the influencing factors and mechanisms of the moisture susceptibility of WMA, surface free energy (SFE) tests and laboratory tests are applied in this research. A novel indicator based on SFE, namely, effective adhesion work, is proposed to assess the asphalt-aggregate adhesion with different moisture contents. Then, given the mixing procedure of the dry-mixing method, an advanced three-phase model as a form of asphalt-aggregate-warm mixing additive is introduced, improving the conventional two-phase asphalt-aggregate model for better reflecting the separate addition of warm-mixing additives during mixing. Afterwards, the influence of aggregate type, asphalt type, aggregate moisture content, warm-mixing agent type, and the warm-mixing process on the moisture susceptibility of WMA is analyzed utilizing the models and indicators proposed. Finally, the validity of the SFE indicator is verified by comparing the calculation of effective adhesion work with freeze-thaw splitting test results. The results show that all of the above factors impact the moisture susceptibility of WMA by influencing the interfacial adhesion, with the effect of moisture content being the most significant. Meanwhile, effective adhesion work and the three-phase model brought out in this research are proven to be feasible to characterize the adhesion properties of WMA, offering theoretical support to the research on warm-mixing technology.

Adsorption of pulmonary and exogeneous surfactants on SARS-CoV-2 spike protein

COVID-19 is transmitted by airborne particles containing virions of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Coronavirus virions represent nanoparticles enveloped by a lipid bilayer decorated by a “crown” of Spike protein protrusions. Virus transmission into the cells is induced by binding of Spike proteins with ACE2 receptors of alveolar epithelial cells. Active clinical search is ongoing for exogenous surfactants and biologically active chemicals capable of hindering virion-receptor binding. Here, we explore by using coarse-grained molecular dynamics simulations the physico-chemical mechanisms of adsorption of selected pulmonary surfactants, zwitterionic dipalmitoyl phosphatidyl choline and cholesterol, and exogeneous anionic surfactant, sodium dodecyl sulfate, on the S1-domain of the Spike protein. We show that surfactants form micellar aggregates that selectively adhere to the specific regions of the S1-domain that are responsible for binding with ACE2 receptors. We find distinctly higher cholesterol adsorption and stronger cholesterol-S1 interactions in comparison with other surfactants, that is consistent with the experimental observations of the effects of cholesterol on COVID-19 infection. Distribution of adsorbed surfactant along the protein residue chain is highly specific and inhomogeneous with preferential adsorption around specific amino acid sequences. We observe preferential adsorption of surfactants on cationic arginine and lysine residues in the receptor-binding domain (RBD) that play an important role in ACE2 binding and are present in higher amounts in Delta and Omicron variants, which may lead to blocking direct Spike-ACE2 interactions. Our findings of strong selective adhesion of surfactant aggregates to Spike proteins have important implications for informing clinical search for therapeutic surfactants for curing and preventing COVID-19 caused by SARS-CoV-2 and its variants.

Experimental investigation on the application of concrete produced with limestone and dolomitic limestone aggregates in building constructions

Concrete, which is frequently used in the production process of buildings; It is made by mixing cement, water, aggregate and additives in appropriate amounts. It is important that the physical, chemical, mineralogical and especially mechanical properties of the concrete are at the desired level in terms of strength and durability of the built structures. In this direction, the selection of aggregates, which are an important part of the concrete mix, is one of the important factors affecting the concrete properties. The use of limestone and dolomitic rocks, which are rocks of sedimentary origin, in the selection of aggregates, strengthens the adhesion of aggregates with cement and improves the properties of the concrete mixture. In this study, it was aimed to identify and classify the rocks in the Western Anatolian region of Turkey and to investigate the suitability of their use as aggregates in concrete. In this context, when the physical, chemical and mineralogical properties of the rock samples taken from the field area were examined, it was understood that the rock samples were limestone and dolomitic limestone samples. In order to compare the performance of concrete mixtures prepared using limestone and dolomitic limestone aggregates, a total of 18 concrete samples were prepared, including limestone crushed aggregate, dolomitic limestone, and limestone and dolomitic limestone aggregates used together. At the end of the 7 and 28 days curing period, the concrete compressive strengths of the prepared samples with the intention of being used as concrete in building structures were tested and compared.

Investigation of the adhesion and debonding behaviors of rubber asphalt and aggregates using molecular dynamics simulation

This paper investigates the interface property between rubber asphalt and aggregates using molecular dynamics simulations to address the adhesion and debonding properties. The effect of aggregate types and rubber contents on rubber asphalt-aggregate systems' adhesion and debonding properties were investigated. The work of adhesion characterized the adhesion property while debonding characteristics were evaluated by the work of debonding and energy ratio (ER). The results show that the impact of aggregate types on the adhesion and debonding between rubber asphalt and aggregates is much more significant than rubber contents. The work of adhesion between four aggregates and rubber asphalt is evaluated as follows: microcline > albite > quartz > calcite. The reason is that the electrostatic energy can considerably contribute to the adhesion at the interface for strong alkali aggregates (microcline, albite) and rubber asphalt, while the van der Waals energy can only contribute nearly 100 mJ/m2 energy for the adhesion. The work of debonding for the four aggregates with rubber asphalt follows the order: microcline > quartz > albite > calcite. Therefore, microcline presents extraordinary performance, while calcite shows the poorest response in moisture resistance.

INCREASING THE ADHESION OF BITUMEN
 IN ASPHALT CONCRETE ON STEELMAKING SLAGS
 MODIFICATION BY NANOADDITIVES

Previously, asphalt concrete mixtures based on metallurgical waste were
 developed, which have a number of valuable qualities and contribute to the disposal of these
 industrial wastes (RF Patent No. 2787268). Long-term tests of these materials revealed insufficient resistance to aging of the asphalt-resinous complex, therefore, additional
 studies were conducted to find ways to increase the adhesion of the slag aggregate in asphalt
 concrete. Modification of bitumen binder with nanoscale additives was proposed as one of
 the measures, which is positively noted by a number of researchers. The article presents the
 results of studying the effect of nano-additives in bitumen on the adhesive and other
 properties of asphalt concrete on steelmaking slags.

Evaluation of Moisture Susceptibility of Asphalt Mixtures: Influence of Aggregates, Visual Analysis, and Mechanical Tests

Asphalt pavement failure is directly related to the traffic and climate effects. Temperature and moisture severely impact pavement service life. It is known that moisture changes the stiffness and stress–strain distribution and all the mechanical behaviors of the mixture/structure. There is a huge interest in studying the impact of water on the behavior of flexible pavements, mainly on freeze–thaw regions under tropical climates with high rainfall levels. The scope of the present paper was to check the susceptibility to moisture-induced damage of dense asphalt mixes produced and applied on highways in Brazil’s southernmost region using different laboratory tests: visual adhesion of coarse aggregate; tensile strength ratio (TSR), and dynamic modulus ratio (DMR). Thus, this study evaluated the morphological, chemical, and mineralogical properties of aggregates from 11 quarries, as well as the interaction between aggregates and the respective bituminous binders. Rocks with high Si contents performed worse in visual adhesiveness tests; chemical ratios such as Fe/Si above 1 and Ca/K above 5, as well as the rougher texture of aggregates, considerably improved the coating, reducing the failures in adhesion. Results of TSR and DMR, after applying the induced moisture damage cycle, indicated greater susceptibility to conventional binders than mixtures containing modified binders in their composition. The action of moisture damage for most mixtures caused a reduction in strength and stiffness, warning of a decrease in the binder’s ability within the mixture, completely changing the distribution of efforts within the structure. Therefore, from this study, it is possible to suggest using DMR instead of TSR to assess susceptibility to moisture damage.

Molecular dynamics simulation of interfacial adhesion behavior between waterborne epoxy resin emulsified asphalt and aggregate

ABSTRACT Understanding the microscopic adhesion behaviour and mechanism of waterborne epoxy resin emulsified asphalt (WEREA) at the aggregate interface is quite significant for improving the service life of pavements. This work created an interface model of WEREA and aggregate using molecular dynamics (MD) simulation to examine the interface adhesion behavior. The interface model based on MD simulation was used to evaluate the distribution characteristics of asphalt components on the aggregate surfaces by calculating the thermodynamic properties, radial distribution function (RDF), relative concentration (RC) distribution and mean square displacement (MSD). The results show that WEREA has better thermodynamic characteristics than base asphalt and has components with much better self-polymerization behaviour. WEREA adheres more tightly to alkaline aggregates than acidic ones. Van der Waals forces dominate interfacial adhesion to acidic aggregates, while that to alkaline aggregates is dominated by electrostatic forces. Interfacial water damage is a spontaneous reaction. Moisture has a substantial influence on asphalt – aggregate adhesion, especially with alkaline aggregates. This work provides an effective method for exploring WEREA – aggregate adhesion.

Effect and mechanism of waste glass powder silane modification on water stability of asphalt mixture

The loss of adhesion is one of the primary mechanisms of water damage in asphalt mixes containing waste glass powders (WGPs), which is mainly attributed to the smooth surface of the glass may undermine the bitumen–aggregate adhesion and accelerate the stripping. In this study, the WGPs surface was roughened by different types and content of silane coupling agent (SCA), and the surface modification mechanism was illustrated based on the chemical reaction process. Then the adsorption capacity of WGPs on SCA was studied through UV–vis tests, and the effects of the SCA on the chemical composition of WGP and asphalt were investigated by FT-IR tests. At the same time, the adhesion performance between modified WGPs and asphalt was studied by the sessile drop test and column wicking test. Furthermore, the immersion Marshall tests were completed to study the water stability of the asphalt mixture after the replacement of filler with modified WGPs. Results show that the optimal modified time of WGPs is 75 min. During the modified process, a ≡Si-O-Si≡ skeleton structure is generated between the SCA and WGPs, and the amino group in SCA reacts with the carboxylic acid of the asphalt to form a new chemical bond. In addition, adding 10 % KH550 SCA to modify the WGPs will provide the most superior improvement for the adhesion work, stripping work and water stability.

Study of Anti-Stripping Measures to Improve the Adhesion of Asphalt to Granite Aggregates

Granite is very widely distributed in the world, but granite is an acidic aggregate with poor adhesion to asphalt. In untreated asphalt mixtures, asphalt pavement water damage and loose disease are more prominent, affecting the service life of the pavement and service level. Enhancing the road performance of granite asphalt mixture generally improves the adhesion properties of asphalt and granite. Qingchuan rock asphalt, anti-stripping agent KH5, aliphatic amine anti-stripping agent AJ-1 and two groups of the composite anti-stripping agents were used to modify the asphalt and analyze the effect of different anti-stripping agents on the improvement of asphalt-granite aggregate adhesion properties based on the surface free energy (SFE) theory. Second, the effect of anti-stripping agents on the rheological properties of asphalt were analyzed by rheological tests, and the modification effect of granite asphalt mixture road performance was evaluated by Marshall tests. The aging of asphalt and asphalt mixture was simulated by thermal oxygen aging, and the durability of different anti-stripping agents was investigated by comparing the performance of asphalt and asphalt mixtures before and after aging. The results showed that Qingchuan rock asphalt can effectively enhance the high-temperature stability and anti-aging properties of asphalt mixes, but the low temperature performance was relatively poor. KH5 and AJ-1 can make up for the lack of low temperature performance of rock asphalt, but the water stability of asphalt mixes decreases after aging. All five groups of anti-stripping agents improve the adhesion of granite-asphalt and the water stability of the asphalt mixture to some extent. Considering the aging effect, the order of granite-asphalt mixture water stability is: KH/RAMA > AJ/RAMA > RAMA > KHMA > AJMA.

Experimental investigation on the effects of a new anti-stripping additive on performance properties of asphalt and its mixtures

• A new compound anti-stripping additive called DMA-NSDD was developed. • The asphalt and its mixture performance was investigated by experiments. • A comparison was made of the performance of seven asphalts and their mixtures. • The performance of asphalt with DMA-NSDD and its mixtures was markedly improved. This study aims to investigate the effects of a new compound anti-stripping additive called DMA-NSDD, which comprised dopamine methacrylamide (DMA) that is a marine biomimetic material and nano-silicon dioxide dispersion (NSDD), on the performance properties of asphalt and its mixtures by experiments. The main steps of DMA synthesis were described. The test methods used in this study for asphalt and asphalt mixture performance were also introduced. The performance properties of asphalt with DMA-NSDD and its mixtures were investigated by comparing with those of virgin asphalt, styrene–butadienestyrene (SBS) modified asphalt, anti-stripping asphalts DMA, NSDD, LYKB™, and GLWS™, and their mixtures. Results showed that the marine biomimetic material DMA could be used in asphalt and its mixtures to increase their performance properties. Compared with SBS, DMA, NSDD, LYKB™, and GLWS™, the asphalt–aggregate adhesion and water stability of the asphalt mixtures with DMA-NSDD were the best and enhanced most significantly. The high- and low-temperature performance of the asphalt mixtures with DMA-NSDD was also notably improved, although it was second only to that of the SBS-modified asphalt mixtures. Overall, with DMA-NSDD, the performance properties of asphalt mixtures with granite aggregates improved more than those of asphalt mixtures with limestone aggregates.

Adhesion Characterization of Palm Oil Mill Sludge Modified Asphalt Binder

The adhesion of mineral aggregates to asphalt binder is an essential point that attributes to the quality and performance of the asphalt mixture. Moreover, the considerable problem to the asphalt pavement could come from the lack of bonding between the materials. Generally, adhesion of mineral aggregates depends on the source or type of aggregate and asphalt binder. This study investigated the adherence coverage of palm oil mill sludge (POMS) modified binder with granite aggregate. Base asphalt binder of penetration grade 60/70 was blended with 1%,2%,3%,4% and 5% of POMS to produce the modified asphalt binders, respectively. Consequently, POMS modified binders were mixed with the granite aggregate to produce loose mix samples. In this current study, boiling test procedure was used to reduce the adhesive bonding of the loose mix sample. Then, Image J software was used to evaluate the stripping area of the samples. The results from image analysis revealed that different stripping areas due to different amounts of POMS incorporated in the modified asphalt binder. Up to 4% POMS modified asphalt showed an acceptable resistance toward moisture compared to un-modified asphalt. Image J helped to produce a clear stripping result compared to visual observation. In conclusion, POMS could be used as an asphalt modifier with satisfactory adhesion properties.