Surface Free Energy Tests Research Articles

Diffuse plasma surface modification of natural rubber-based composite

The article investigates the effect of diffusion plasma exposure time (30 s, 60 s) on the physicochemical properties of the surface of a natural rubber-based composite. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) with dispersive X-ray spectroscopy (EDS) were used to assess the properties. Wettability and surface free energy tests were also performed. The application of plasma leads to surface oxidation (EDS). The obtained properties did not change for 21 days, and the plasma exposure time had no significant effect on the physicochemical changes of the composite surface.

Reducing the moisture susceptibility of recycled hot‐mix asphalt mixture with composite modification technology

AbstractStyrene–butadiene–styrene block copolymer (SBS)‐modified asphalt is a key material for constructing recycled hot‐mix asphalt mixtures (RHMAs). However, these mixtures still risk insufficient moisture stability. To this end, this study investigates the feasibility of asphalt composite modification technology to enhance RHMA performance. SBS, high‐viscosity agent (HVA) and crumb‐rubber materials (CRM) were used to prepare SBS‐HVA‐ and SBS‐CRM‐modified asphalt, with SBS‐modified asphalt as the control group, and the adhesion properties of the asphalt were evaluated using surface free energy tests. RHMAs with 50% reclaimed asphalt pavement were then prepared with each type of modified asphalt. The moisture susceptibility of these mixtures was analyzed using moisture‐induced sensitivity, freeze–thaw splitting and immersion Marshall tests. It was found that HVA significantly enhanced the adhesion of SBS‐modified asphalt under dry conditions, while CRM had a minimal effect. Compared to RHMA with SBS‐modified asphalt, HVA and CRM additives are crucial for enhancing the moisture stability of RHMA in the immersion Marshall test. However, CRM does not improve the moisture stability of RHMA in the moisture‐induced sensitivity and freezing–thaw splitting tests. From the conducted study, it can be proposed that SBS and HVA composite‐modified asphalt can be utilized in RHMAs to achieve higher moisture stability. © 2024 Society of Chemical Industry.

Using surface free energy and mechanical methods to investigate the effect of aging on the fatigue cracking potential of UHMWPE-modified HMA

Aging due to environmental conditions significantly affects the occurrence of fatigue cracking in hot-mix asphalt (HMA). Previous analyses showed that aging reduces mastic resistance and bitumen-aggregate adhesion, but these experiments were usually performed on HMA samples, and failure mechanisms were not reflected in the results. Accordingly, via the surface free energy (SFE) theory, this study examined the impact of aging on the fatigue cracking mechanism of HMA. Dynamic methods, including indirect tensile fatigue test (ITFT) and Pull-Off tensile strength (POTS), were applied to HMA samples at 5 and 20 ˚C to study the association between the results of SFE tests. Two performance-graded bitumens (PG 58–22 and PG 64–16), two aggregates with different mineralogical properties (limestone and siliceous), and a polymeric additive (ultra-high-molecular-weight polyethylene-UHMWPE) as a bitumen modifier were also used. Based on the results, aging decreased and increased the polar (28.6%) and non-polar (15.14%) properties of bitumens, respectively. A decline in polar properties lowered the bitumen-aggregate adhesion (8.11%), which was generally because of polar bonds. The rise in cohesion free energy (CFE) by up to 9.5% and non-polar properties due to aging decreased the failure probability in the bitumen film of the aged specimens. UHMWPE improved the non-polar properties of the asphalt (by up to 15.09%), providing greater resistance against aging and reduced adhesion with mineral aggregates. According to the POTS test results at the state of cohesive failure, aging enhanced the POTS of cohesion, especially in UHMWPE-modified bitumen-aggregate by up to 12.12%. POTS in the state of cohesive failure was independent of adhesion free energy (AFE), yet CFE influenced POTS at the state of adhesive failure. Based on the fatigue life of HMA, even though aging increased the CFE and stiffness of HMA, the decline in the AFE parameters and flexibility reduced the fatigue life of the aged HMA in comparison to similar non-aged specimens (by up to 5.17%). The polymer additive significantly improved the resistance of asphalt mixtures to cohesion (by up to 23.16%), adhesion (by up to 16.78%), and fatigue life (by up to 12.8%). Additionally, in aged samples, there was a noticeable reduction in the parameters of cohesion, adhesion, and fatigue life in the modified samples compared to the base samples.

Influence of Light-Curing Glaze and Chlorhexidine Gluconate in the Acrylic Resin Properties: An in situ Study.

This in-situ study aimed to evaluate the chromatic stability, microhardness, and surfacefree energy of chemically activated acrylic resin (CAAR) samples. Eighty CAAR samples were made and each volunteer (n = 20) received two palatal plates with two sides of groups (without and with glaze application). The samples were exposed to two conditions: the control condition (sucrose 30%) and the test condition (sucrose 30% and 0.12% chlorhexidine). The volunteers used the first palatal device (control condition) for seven days and the second palatal device (test condition) for another seven days, with a seven-day break between them. Then, the ΔΕ00, microhardness, and surface-free energy tests were performed. Analysis of Variance and the Tukey test were used (α = 0.05). The control group with glaze showed higher ΔΕ00 compared to the group without the glaze. The test group with glaze had less ΔΕ00 than their respective controls. In both periods, when the glaze was applied, higher microhardness values were found for all groups. Groups with glaze showed lower roughness and higher surface-free energy than groups without the glaze. The values obtained in this study were satisfactory, showing the clinical efficacy of glaze and the use of 0.12% CH for maintaining the physical and mechanical properties of CAAR.

Free surface energy evaluation in the laser texturing of a carbon steel s275

Currently, the manufacture of hybrid structures of dissimilar materials is generating great interest. These allow to combine mechanical properties of different materials to achieve a higher functional performance. To obtain these structures, different joining technologies are used, especially the use of adhesives. Nevertheless, for the correct application of an adhesive, the surface of the metal to be bonded must be prepared. Laser texturing has become a widely studied technology for this purpose because it allows very defined textures to be obtained. This technology allows to activate the surface and improve the application of the adhesive afterwards. In that sense, hydrophilic surfaces are generated and evaluated by wettability tests to know the surface free energy obtained in the texturing.In order to improve the bonding of dissimilar materials in the form of hybrid structure, a study has been carried out on the laser texturing of a carbon steel S275 and the relationship between the texturing parameters with its surface activation through wettability and surface free energy tests. Thus, the energy density obtained by the combination of power and scanning speed allows the generation of very defined textures that increase the surface activation of the steel. This has made it possible to establish a mathematical relationship between the texturing parameters and the results obtained.

Effect of polymer modified bitumen emulsion production method on the durability of recycled asphalt mixture in the presence of deicing agents

This study investigated the effects of polymer modified bitumen emulsion production methods on the microstructural properties of modified binders and the mechanical properties of cold recycled mixtures with a more emphasis on durability. Modified bitumen emulsions containing styrene butadiene rubber (SBR) produced using three methods, including soap pre-batching, post-blending and co-milling. Surface free energy (SFE) and atomic force microscopy (AFM) tests have been used to inquire into the fundamental and microstructure properties of samples. Indirect tensile strength and dynamic modulus tests were used to investigate the mechanical properties of cold recycled mixtures. Mechanical properties of mixtures were investigated in dry state, after saturation and placement in the freeze-thaw (F-T) cycles with and without deicing agents including calcium magnesium acetate (CMA) and calcium chloride (CaCl2). Accordingly, the soap pre-batching method had the most suitable performance in terms of dynamic modulus at high temperatures and superior durability under F-T cycles. The samples made by soap pre-batching method showed the lowest surface roughness, maximum adhesion and the highest cohesive energy and surface free energy based on the results of AFM and SFE tests, which were effective in improving the mixture performance. Overall, the post-blending and co-milling methods can be rated as the second and third ranks in terms of both mechanical and nano-mechanical properties, respectively. Finally, in comparison with CaCl2, CMA salt significantly reduced the destructive effects of F-T cycles on the mechanical properties of recycled mixture.

Influence of Bio-oil Modification on Moisture-Induced Damage Potential of Asphalt Binder and Mix

Abstract Bio-oil (BO) derived from waste wood has the potential to be the modifier for asphalt binders. This study attempts to evaluate the effect of BO on the moisture damage potential of asphalt binder and mix by blending BO at two dosages (2 % and 4 %, by weight) in AC30. BO was obtained by fast pyrolysis of waste wood. To achieve this objective, surface free energy (SFE), bitumen bond strength, and indirect tensile strength tests were conducted for evaluating the cohesive and adhesive bond strength, the work of debonding, energy ratios (ERs), pull off tensile strength (POTS), and tensile strength ratio (TSR). The test results indicated that the addition of BO improves the cohesive and adhesive bond strength. Also, an increase in the work of debonding was observed by conducting the SFE test. Thereafter, ERs indicated that BO has compromised the moisture damage resistivity of AC30. A reduction in POTS was also observed on inclusion of BO. TSR of mixes reduced consistently on BO addition, thereby indicating that BO has compromised the moisture-induced damage resistivity of mixes. However, all mixes resulted in more than 80% TSR value, which is the minimum requirement to counter the moisture-induced damage. A “good” correlation was observed between ERs and TSR. This study concludes that although the inclusion of BO is a promising prospect, BO has the propensity to compromise the moisture-induced damage resistivity of the asphalt mix.

Mechanical evaluation and mechanism analysis of the stripping resistance and healing performance of modified asphalt-basalt aggregate combinations

Asphalt modifications can contribute to the moisture susceptibility and fatigue resistance of asphalt mixtures. This study investigated the effects of various asphalt modifications on the bond and healing properties of modified asphalt binders and the mechanism of changes caused by the modification. Five modified asphalt binders were prepared in the laboratory for this study, including SBS-modified asphalt, crumb rubber-modified asphalt, terminal blend (TB) rubberized asphalt, high-density polyethylene (HDPE)-modified asphalt, and gilsonite-modified asphalt. A modified binder bond strength (BBS) test was applied to evaluate the bond and healing performance of five modified binders at both dry and wet conditions. The surface free energy (SFE) test was conducted on the modified binders to investigate the cohesion/adhesion energy variation due to the binder modification. In addition, the ravelling resistance, moisture susceptibility, and fatigue life of the asphalt mixtures prepared using the modified binders and basalt (which is widely used in China) were measured using the Cantabro test, Hamburg wheel-tracking test, and four-point beam fatigue test, respectively. The performance results of the asphalt mixtures are employed to verify the findings of BBS and SFE tests for the modified binders. It is found that the modified BBS test provides a promising tool for evaluating the bond and healing properties of modified asphalt binders, and the SFE could help to explain the mechanism of binder modification. The testing results indicate that gilsonite enhanced the bond strength and surface energy of asphalt, and high-density polyethylene significantly improve the healing performance.

Surface Characterization and Corrosion Resistance of Biomedical AZ31 Mg Alloy Treated by Microarc Fluorination.

The application prospect of biodegradable materials is being studied extensively. However, the high corrosion rate and its alloys in body fluids have been major limitations of the application of pure Mg (magnesium). To improve corrosion resistance of biodegradable AZ31 Mg alloy, we adopted microarc fluorination within a voltage range of 100-300 V in 46% hydrofluoric acid. To obtain morphologies, chemical compositions, and structural characteristics, field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were performed, respectively. Results showed that the coating was mainly composed of MgF2. Electrochemical corrosion and immersion tests proved that the corrosion resistance of MAF-treated AZ31 Mg alloy was significantly improved compared with untreated AZ31 Mg alloy in HBSS (Hank's Balanced Salt Solution). Current densities of AZ31, MAF100, MAF150, MAF200, MAF250, and MAF300 were 342.4, 0.295, 0.228, 0.177, 0.199, and 0.212 μA/cm2, respectively. The roughness test indicated that samples under MAF treatment of 200 V, 250 V, and 300 V had large surface roughness. Meanwhile, the contact angle measurement and surface free energy test suggested that those samples had smaller contact angle and higher SFE than Ti. Thus, MAF-treated AZ31 Mg alloy might have promising application in various fields.

Investigation of the chemical, strength, adhesion and morphological properties of fly ash based geopolymer-modified bitumen

The current study seeks to investigate the chemical, strength, adhesion and morphological properties of fly-ash based geopolymer-modified bitumen (GMB). The geopolymer was prepared by mixing class F fly ash with alkaline solution (sodium silicate and sodium hydroxide), and was then mixed with an 80/100 penetration grade bitumen at different concentrations of 3, 5, 7 and 9% (by weight of bitumen) to produce the GMB. The chemical and strength properties of the binders were determined using the Fourier Transform Infrared Spectroscopy (FTIR) and Impact tests, respectively. The Surface Free Energy (SFE) and Atomic Force Microscope (AFM) tests were conducted to establish the adhesion and morphology of the binders. The modification of base bitumen with geopolymer resulting the improvement in structural chain mobility properties and improved storage stability compared to those of the control sample. The result of FTIR analysis showed that the incorporation of geopolymer into base bitumen did not cause any change in the functional groups, where the peaks of aromatic CC stretching is at around 1600 cm−1 (stretch), 1475 cm−1 (stretch) and 900–600 cm−1 (out-of-plane bend). The peak at around 1390 cm−1 clearly shows the stretch of the C-N amine group. The result of SFE test shows that GMB has better resistance to moisture damage. Finally, the AFM analysis revealed morphological changes in all GMB samples. In general, the addition of 5% geopolymer can be considered as is the optimum concentration for bitumen modification.

The effect of water solution erosion on rheological, cohesion and adhesion properties of asphalt

Asphalt pavement will be damaged under the action of asphalt aging and moisture damage. Water solution erosion degree is closely related to the aging of asphalt and degradation of the adhesive strength between asphalt and aggregate. In view of this, this paper investigated the effect of water solution erosion on rheological, cohesion and adhesion properties of virgin and aged asphalt. The experiment was performed by immersing asphalt into five different water solutions (includes distilled water, acid solution, alkali solution, sodium chloride solution and sodium sulfate solution) for different time, which was considered to be fully reflect the real service condition within an asphalt pavement in different areas. The rheological properties were evaluated by dynamic shear rheometer (DSR), the cohesion and adhesion properties based on the surface free energy test were got by sessile drop method. Meanwhile, the relationships between asphalt rheological, cohesion and adhesion properties with aqueous solute and water solution erosion time were studied. The effects of water solution erosion on virgin asphalt and its PAV aged asphalt were compared. It was observed that water solution erosion resulted in the increased of asphalt elastic component and stiffness, decreased of asphalt fatigue life and the cohesive force and adhesion to aggregates. This trend was reduced to some extent with the presence of acid, alkali, and salt solutes. Under the action of water solution erosion, PAV aged asphalt showed a worse resistance to water solution erosion. And unlike heat-aging and ultraviolet-aging, the development trends of rheological, cohesion and adhesion properties of asphalt were more complex and variable with the change of asphalt surface component.

Effect of different viscous rejuvenators on chemical and mechanical behavior of aged and recovered bitumen from RAP

Due to scarcity of virgin natural materials, the use of reclaimed asphalt pavement (RAP) has been promoted and encouraged in pavement engineering. However, note that the bituminous binder in RAP has been seriously aged due to long-term service exposure to the atmosphere. It is thus paramount to effectively restore properties of the RAP by adding proper rejuvenators. In this study, five rejuvenators were designed with different viscosities and applied to rejuvenate the aged binder. The changes in chemical compositions of bitumen caused by ageing and rejuvenating were evaluated by a SARA (Saturate, Aromatic, Resin and Asphaltene) analysis method. Brookfield viscosity, Dynamic Shear Rheometer (DSR) and Direct Tension (DT) were further conducted to evaluate the physical and mechanical properties of bituminous binders. Surface Free Energy test was applied to characterize the adhesion and moisture damage behavior of aged and rejuvenated binders. The experimental results showed that the ageing process increased resins and asphaltenes, which in turn improved the colloidal stability of the aged binder. The five rejuvenators designed in this research had a similar effect in restoring the rheological properties and stiffness of the aged bitumen to a similar level as that of the virgin binder. However, the viscosity level of rejuvenator has different impacts on tensile elongation at break, brittle fracture stress, adhesion property and moisture resistance of rejuvenated binders, in which the rejuvenator with an optimal viscosity may obtain the best rejuvenating performance.

Epoxy‐functionalized polysiloxane reinforced epoxy resin for cryogenic application

ABSTRACTThe poor cryogenic mechanical properties of epoxy resins restrict their extensive application in cryogenic engineering fields. In this study, a newly synthesized epoxy‐functionalized polysiloxane (PSE) is used to improve the cryogenic mechanical properties of bisphenol‐F epoxy resin. The Fourier transform infrared spectra and nuclear magnetic resonance confirm the formation of epoxy‐functionalized –Si–O–Si– molecular chain. The surface free energy test results show that the PSE has a better compatibility with epoxy resin. The mechanical test results show that the cryogenic tensile strength, failure strain, fracture toughness, and impact strength of epoxy resin is improved significantly by adding the suitable amounts of PSE. Compared to the neat epoxy resin, the maximum tensile strength (196.92 MPa, an improvement of 11.2%), failure strain (2.97%, an improvement of 33.8%), fracture toughness (3.05 MPa·m1/2, an improvement of 30.7%) and impact strength (40.55 kJ m−2, an improvement of 14.8%) at cryogenic temperature (90 K) is obtained by incorporating 10 wt % PSE into the neat epoxy resin. Moreover, the results also indicated that the tensile strength, Young's modulus, and fracture toughness of epoxy resin with the same PSE content at 90 K are higher than that at room temperature (RT). © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2019,136, 46930.

Effects of Asphalt Binder Modifying with Polypropylene on Moisture Susceptibility of Asphalt Mixtures with Thermodynamically Concepts

In this study, the effect of using Polypropylene (PP) as an antistripping additive of asphalt mixtures is investigated. Here, the moisture susceptibility of asphalt mixtures is evaluated by determining the micro-mechanisms using the surface free energy (SFE) concept. The adhesion bond between the aggregate and asphalt binder and the cohesion strength of the asphalt binder are considered as the main factors that affect moisture damage of asphalt mixtures. Test results indicate that the use of PP improves the resistance of asphalt mixtures in both wet and dry conditions. Also, the results of the SFE tests showed that the modifying asphalt binder with PP increases free energy of adhesion that will improve adhesion resistance between asphalt binder-aggregates. The amount of debonding energy in the samples which are modified with PP is lower than the control samples. This shows that by modifying asphalt binders, the tendency of asphalt binder-aggregate stripping can be reduced. The results show the total SFE of the asphalt binders of the modified samples have more free energy rather than the control samples. This phenomenon shows that failure in the asphalt binder film and cohesion failure will be happened more rarely.

Determining the water damage resistance of nano-clay modified bitumens using the indirect tensile strength and surface free energy methods

Water infiltration into asphalt mixtures is one the serious distresses which lowers the performance of the top layer of road pavements. This problem is even worse in tropical countries which experience high temperature and heavy rainfalls. Therefore, this study aims to evaluate the effects of water infiltration on a 60/70 penetration grade bitumen vis-a-vis bitumen modified with 2 and 4% nano-clay. The Fourier Transform InfraRed (FTIR) test was done to identify any chemical changes that might occur in the nano-clay and the bitumen. The loose and compacted mixtures of the nano-clay modified bitumen were tested to determine their resistance to water damage. The loose mixture was tested by conducting the boiling water, the Vialit adhesion, and surface free energy (SFE) tests, while the compacted mixture was tested using the indirect tensile strength (ITS) test. Aging simulation was done for samples tested using SFE and ITS. The results of the tests show that adding nano-clay alters the mixtures’ ability to resist water damage. The improvement in the samples varies depending on the type of binder as well as its aging stage. Unaged bitumen modified with 2% nano-clay show better ability to resist water damage compared to both the unmodified bitumen and the bitumen modified with 4% nano-clay. However, after being subjected to short-term aging (STA) and long-term aging (LTA), the results of both the ITS and SFE tests show that the addition of 4% nano-clay enhance the bitumen’s resistance to water damage in comparison with the unmodified bitumen and the bitumen modified with 2% nano-clay. The addition of nano-clay reduces water’s effect on the binder, hence indicating the benefit of using nano-clay as an additive to mitigate water effect.

Effects of Polymeric Coating the Aggregate Surface on Reducing Moisture Sensitivity of Asphalt Mixtures

This paper presents the theoretical and experimental concepts of predicting moisture damage in asphalt concrete mixes using the surface free energy (SFE) concept and laboratory dynamic test, respectively. The SFE characteristics of aggregates and asphalt binders have been evaluated using a Universal Sorption Device (USD) and Wilhelmy Plate (WP) methods, respectively. To validate the results of SFE tests, a dynamic modulus test was conducted on the asphalt mixtures in a controlled stress mode under dry and wet conditions. The results of this study show that the polyvinyl chloride (PVC) coating decreases significantly the total SFE and polar SFE, and leads to an increase in the non-polar SFE of the aggregates, which make aggregates be hydrophobic. This occurrence increases the coating ability of aggregates by the asphalt binder. Comparison between the results of dynamic modulus test in dry and wet conditions confirms the results obtained from the SFE method. P index, which is the percentage of the aggregate surface that experiences stripping in different cycles of loading in wet condition, is obtained by the relation between the concepts of two investigated methods in this study.

Evaluation of the degradation of fine asphalt-aggregate mixtures containing high reclaimed asphalt pavement contents

This paper evaluates the mechanical properties and performance of the fine aggregate matrix (FAM) existing within full reclaimed asphalt pavement (RAP) asphalt mixtures, in terms of their rheological and fatigue deterioration properties. The RAP material was produced in the laboratory to control its properties and to reduce the effects of variability associated with these materials. Four FAM mixtures were analysed, including a virgin hot mix asphalt, a 100%RAP, and two mixtures containing 50% RAP in combination with virgin materials using different penetration grade virgin binders. The analysis of the deterioration properties was based on the application of a fracture model that incorporates the viscoelastic properties of the material, the quality of the adhesive bonds developed between the aggregates and the corresponding bitumen present in each mixture, and the rate at which the material dissipates energy when subjected to cycling loading. The input parameters for this model include the results obtained from dynamic mechanical analysis and surface free energy tests. In general, the results showed that the incorporation of 50% RAP content increased the stiffness of the final mixtures, as expected. However, this hardening effect did not result in mixtures with inferior fatigue performance of the FAM present in the full mixtures, at the applied strain level.

Investigation to test potential stereolithography materials for development of an in vitro root canal model.

The aims were to compare the physico-chemical properties (zeta-potential, wettability, surface free energy) of stereolithography materials (STL) (Photopolymer, Accura) to dentine and to evaluate the potential of each material to develop Enterococcus faecalis biofilm on their respective surfaces. Eighteen samples of each test material (Photopolymer, Accura, dentine) were employed (total n = 54) and sectioned to 1 mm squares (5 mm x 5 mm) (n = 15) or ground into a powder to measure zeta-potential (n = 3). The zeta-potential of the powder was measured using the Nano-Zetasizer technique. The contact angle (wettability, surface free energy tests) were measured on nine samples using goniometer. The biofilm attachment onto the substrate was assessed on the samples of each material using microscope and image processing software. The data were compared using one-way ANOVA with Dunnett post-hoc tests at a level of significance P ≤ 0.05. Both STL materials showed similar physico-chemical properties to dentine. The materials and dentine had negative charge (Accura: -23.7 mv, Photopolymer: -18.8 mv, dentine: -9.11 mv). The wettability test showed that all test materials were hydrophilic with a contact angle of 47.5°, 39.8°, 36.1° for Accura, Photopolymer and dentine respectively, and a surface free energy of 46.6, 57.7, 59.6 mN/m for Accura, Photopolymer and dentine, respectively. The materials and dentine proved suitable for attachment and growth of E. faecalis biofilm with no statistical differences (P > 0.05). Stereolithography materials show similar physico-chemical properties and growth of E. faecalis biofilm to dentine. Therefore, they may be an alternative to tests requiring dentine.

Moisture susceptibility of hot mix asphalt containing asphalt binder modified with nanocomposite

There are several methods to improve moisture susceptibility of asphalt mixtures that using additives or modifiers is the most common method in this regard. In this research, a new nanocomposite material was used for improving the moisture susceptibility of the asphalt mixtures. The experimental design included one base asphalt binder, two types of aggregates (granite and limestone) and 2% of nanocomposite (polypropylene/nanoclay). Indirect tensile strength and surface free energy tests were conducted to evaluate the moisture susceptibility of the asphalt mixtures. The surface free energy components of the aggregates and asphalt binders were obtained using universal sorption device and Wilhelmy plate methods, respectively. The test results showed that the tensile-strength-ratio values of the asphalt mixtures containing nanocomposite had improved. In addition, the results of surface free energy test indicated that the nanocomposite could be used to improve the moisture susceptibility of the asphalt mixtures.

Use of Surface Free Energy method to evaluate the moisture susceptibility of sulfur extended asphalts modified with antistripping agents

Aggregate–asphalt binder adhesion bond is a vital factor that affects the resistance of asphalt mixtures against moisture damages. Since, moisture damages are the main defects of sulfur extended asphalts (SEAs), this study aims to improve it by reinforcing the adhesion between asphalt binder and aggregate. An antistripping additive named nanotechnology Zycotherm (NZ) was used to achieve this goal. Surface Free Energy (SFE) method was applied to examine the effectiveness of NZ additive in improving the moisture susceptibility of SEA. The research team utilized two common mechanical tests (indirect tensile strength, and dynamic modulus) to evaluate the validation of SFE method. All samples were constructed with two different aggregates, limestone and granite. In the SFE method, the measured surface energy components of constitutive materials were used to calculate the bond strength between them in dry and wet conditions. The findings showed that adding NZ was a successful technique to compensate the deteriorated adhesion due to using sulfur. Also it was demonstrated that SFE test results were so compatible with the common mechanical tests in predicting moisture damages.