Boiling Water Test Research Articles

Adhesion performance and enhancement mechanism of FA/GGBFS based geopolymer modified bitumen and acidic aggregate

The primary challenge in utilizing acidic aggregates in bitumen mixtures lies in enhancing the adhesive bond between the bitumen and the acidic aggregates. In this manuscript, to investigate the adhesion of different geopolymer modified bitumen with acidic aggregates, fly ash geopolymer (FG), fly ash- ground granulated blast furnace geopolymer (SFG), and ground granulated blast furnace (SG) were prepared by fly ash (FA), ground granulated blast furnace (GGBFS) with alkali activator. The different geopolymers were characterized with SEM, XRD, FTIR. Different geopolymer modified bitumen was prepared by adding geopolymers into virginal bitumen. The conventional properties, viscosity, and rheological properties of modified bitumen were measured and analysed. The adhesion of bitumen to acidic aggregates was tested by Zeta potential test, the improved boiling water test and pull-off test. The results showed that the electronegativity of bitumen and acidic aggregates were weakened significantly by Na+ in skeletal structure of fly ash geopolymer. The high temperature stability of fly ash geopolymer modified bitumen was improved and the bond strength of bitumen with acidic aggregates increased remarkably with the addition of 9 % fly ash geopolymer.

Performance evaluation of surface treatment waste glass as aggregate in asphalt mixture

Surface modification is a crucial strategy for enhancing the pavement performance of waste glass hot mix asphalt (HMA) mixtures. This study conducts a comparative analysis of various surface modification techniques to pinpoint the key factors that influence the interfacial interaction between waste glass and asphalt. To assess the performance of asphalt mixtures containing surface-treated waste glass, the study employed methods such as Energy Dispersive X-ray Spectroscopy (EDS), boiling water tests, and contact angle measurements, which helped to quantify surface morphology and the effectiveness of different treatments. The evaluation also included assessments of water stability, dynamic stability, small beam bending, and anti-skid properties. Findings revealed that applying a silane coupling agent to the waste glass significantly enhanced adhesion with asphalt, resulting in markedly improved pavement performance. The study identified that incorporating surface-treated waste glass at an optimal proportion of 6 % within the asphalt mixture led to a 42.3 % increase in dynamic stability and a 38.6 % enhancement in anti-skid performance compared to standard mixtures. This research offers a comprehensive evaluation framework for surface modification techniques of waste glass, underscoring its potential to considerably improve road performance.

Mechanism of reinforced interfacial adhesion between steel slag and highly devulcanized waste rubber modified asphalt and its influence on the volume stability in steel slag asphalt mixture

The volume expansion risk of steel slag is a predominant challenge hindering its usage as an alternative aggregate in road pavements. In this study, the interfacial adhesion properties of base asphalt-basalt, base asphalt-steel slag, rubber modified asphalt (RMA) -basalt and RMA-steel slag were compared employing both experiment and molecular dynamics simulation. The volume stability and road performance of the asphalt mixture was also explored. The results showed that the residue rate of the RMA asphalt mixed with steel slag aggregates showed an increase from 87.5 % to 95.7 % compared to base asphalt after 100°C boiling water test. The interfacial adhesion between steel slag and asphalt surpasses that of basalt and asphalt, with the use of rubber modified asphalt further enhancing the adhesion with steel slag aggregates, as investigated through quantitative evaluation of interface adhesive work. The enhanced interaction between steel slag and RMA was primarily due to the integration of acidic functional groups from rubber chain with the alkaline active constituents (f-CaO) of steel slag aggregates, as confirmed by molecular dynamics simulations and accurate density functional theory calculations. Furthermore, the volume stability and road performance of the steel slag stone mastic asphalt were also greatly improved compared with basalt asphalt mixture. The dynamic average stability of RMA steel slag mixture was 9218 cycles/mm and the expansion rate of steel slag asphalt mixture under did not exceed 1.2 % after 216 hours water immersion. Therefore, this study provides an alternative aggregate for road pavement and a sustainable recycling strategy for the steel slag waste.

Self-Neutralizing Melamine-Urea-Formaldehyde-Citric Acid Resins for Wood Panel Adhesives.

In this study, we used a self-neutralizing system to counteract too acidic a pH, unsuitable for wood adhesives, and tested it on MUF resins augmented by the addition of citric acid or other organic acids, based on the addition of small percentages of hexamine or another suitable organic base to form an acid-base buffer. In this manner, the pH of the adhesive was maintained above the minimum allowed value of 4, and the strength results of wood particleboard and plywood bonded with this adhesive system increased due to the additional cross-linking imparted by the citric acid. Thus, the wood constituents at the wood/adhesive interface were not damaged/degraded by too low a pH, thus avoiding longer-term service failure of the bonded joints. The addition of the buffering system increased the strength of the bondline in both the plywood and particleboard, both when dry and after hot water and boiling water tests. The IB strength of the particleboard was then increased by 15-17% when dry but by 82% after boiling. For the plywood, the shear strengths when dry and after 3 h in hot water at 63 °C were, respectively, 37% and 90% higher than for the control. The improvement in the bonded panel strength is ascribed to multiple reasons: (i) the slower, more regular cross-linking rate due to the action of the buffer; (ii) the shift in the polycondensation-degradation equilibrium to the left induced by the higher pH and the long-term stability of the organic buffer; (iii) the additional cross-linking by citric acid of some of the MUF resin amine groups; (iv) the already known direct linking of citric acid with the carbohydrates and lignin constituents at the interface of the wood substrate; and (v) the likely covalent linking to the interfacial wood constituents of the prelinked MUF-citric acid resin by some of the unreacted citric acid carboxyl groups.

Mathematical formulation for predicting moisture damage indices of asphalt mixtures treated with sustainable waste plastic modifiers using gene expression programming

Flexible pavements are susceptible to rutting, fatigue, and moisture damage failures. As a sustainable approach, waste plastic modifiers have been used to improve the moisture damage resistance of asphalt mixtures. However, assessing moisture damage indices such as tensile strength ratio (TSR), rut depth (RD), and loss in Marshal stability (LI) for waste plastic modified asphalt mixtures (WPMAM) via traditional lab methods is time-consuming and resource intensive. As a solution, this study suggests a gene expression programming (GEP) approach for predicting moisture damage indices of WPMAM. The models were constructed based on the outcomes from qualitative lab tests on loose coated asphalt specimens, including the static water immersion test (SWIT), rolling bottle test (RBT), and boiling water test (BWT). The proposed models demonstrated robust performance with high R values and favorable low error metrics. TSR achieved 0.99 (training) and 0.98 (testing) R values, while RD and LI displayed strong predictive accuracy with 0.95, 0.93 (training), and 0.94, 0.77 (testing) R values. Notably, lower root means square error (RMSE), mean absolute error (MAE), and relatively squared error (RSE) values reinforce the models' reliability. Sensitivity analysis identified RBT as the most influential factor for TSR, RD, and LI of WPMAM. Finally, parametric analysis verified the alignment of proposed models with underlying physical processes. Thus, these models can be successfully implemented for predicting moisture damage indices of WPMAM, offering a streamlined alternatives to labor-intensive laboratory procedures, making them valuable for optimizing material choices and implementing preventive measures in construction.

Fabrication of an Ultrastrong Formaldehyde-Free Wood Adhesive with an Organic-Inorganic Cross-Linking Network.

The wood industry faces challenges in producing eco-friendly, high-performance, and formaldehyde-free adhesives. In this study, carboxylated styrene-butadiene rubber (XSBR) was blended with polyamidoamine-epichlorohydrin (PAE) resin, and a controlled amount of CaCO3 powder was incorporated to create an adhesive with exceptional strength. The resulting three-layer plywood demonstrated remarkable dry and wet shear strengths of 3.09 and 2.36 MPa, respectively, and of 2.27 MPa after boiling water tests, comparable to that of phenolic resins. Additionally, the adhesive exhibited strong adhesion across various materials including glass, metal, etc. This exceptional performance was due to two primary factors: (1) the high-density chemical cross-linking reaction and the physical entanglement between XSBR and PAE; (2) the organic-inorganic hybrid involving metal ion complexation developed by CaCO3, which fostered molecular chain connections and enhanced the adhesive-material interface. These findings offer valuable references for further research in the field of wood adhesives.

Evaluation for water stability of bitumen mixture with multi-scale method

The interaction forces were investigated between matrix bitumen and four kinds of aggregates, including basalt, granite, limestone A, and limestone B in various pH solutions. The aim was to accurately evaluate the water damage resistance of bitumen mixtures at macroscopic and microscopic levels with a conjunctive method of boiling water tests, atomic force microscopy (AFM) colloidal probe technique, zeta potential measurements, and molecular dynamics simulation. Macroscopic evaluation was conducted through indoor water-boiled flaking rate tests to analyze the flaking rate and adhesion class of bitumen and aggregate. The microscopic forces were measured by AFM probe technique between bitumen and aggregate, zeta potential measurements were carried out and the extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory was employed to interpret the bitumen–aggregate interaction behaviors. Molecular dynamics simulations were considered to explain the interface binding tendency between bitumen and aggregate. The AFM force measurements showed that the long-range repulsion forces changed to attractive forces and high adhesive forces with the pH change from 4 to 6. However, the strong long-range repulsive forces were decreased, compounded with a relative low adhesion in the alkaline solution. The long-range force between granite and bitumen was a strong attraction, and adhesion was strong when the solution pH was 4, which is a more special phenomenon. It may be due to the electrostatic attraction between the positive charge on the granite surface and the negative charge on the bitumen surface. Zeta potential values of bitumen droplets and aggregate particles exhibited an overall decreasing trend with increasing solution pH, and the variation of surface potential value is consistent with the variation trend of long-range force between aggregate and bitumen. The microscopic forces between bitumen and aggregate measured by AFM were validated by molecular dynamics simulations, revealing a strong correlation between debonding work and interfacial forces. The results indicate that the adhesion between aggregates and bitumen in aqueous solution followed the order: limestone A > limestone B > basalt > granite, and alkaline conditions are not conducive to preventing water damage in bitumen mixtures. It provides insights into the water stability mechanism of bitumen-aggregate at macroscopic and microscopic scales, offering theoretical support for preventing water damage in bitumen pavements.

Interfacial adhesion between recycled aggregate and asphalt mastic filled with recycled concrete powder

Recycled aggregate (RA) and recycled concrete powder (RCP) hold significant potential as environmentally sustainable raw materials for asphalt mixtures. In this study, a comprehensive investigation was conducted on the bonding properties between RA and RCP-filled asphalt mastic (RCPAM). This investigation utilized an image processing-assisted modified water boiling test, binder bond strength (BBS) tests, and the surface free energy (SFE) method. The results indicate that the boiling water test method, even with the assistance of 2D image processing analysis, cannot adequately evaluate the adhesive characteristics of the RA-RCPAM interface. This limitation could be attributed to the relatively small number of samples tested and the significant variation in surface properties of RA. Increasing both the filler-to-asphalt (F/A) ratio and RCP replacement ratio adversely affected the interfacial bond strength of the RA-RCPAM interface. On the other hand, an increase in RA surface roughness contributed to a higher bond strength. Based on the experimental results, a best-fit multivariate mixed model was proposed to predict the interfacial bond strength between RCP-filled asphalt mastic and recycled aggregate within a given range of RCP replacement ratio, surface roughness, and filler-to-asphalt (F/A) ratios. The analysis of SFE suggested that moisture damage to RCPAM was caused by both cohesive and adhesive failure. Additionally, the minimal impact of adhesion work in wet condition with increasing RCP content suggested that adhesion failure energy was only marginally affected by the inclusion of RCP, even in the presence of moisture. These findings are expected to enhance the understanding of interfacial adhesion characteristics and moisture susceptibility of the RA-RCPAM interface.

Study on the Properties and Mechanism of Recycled Aggregate/Asphalt Interface Modified by Silane Coupling Agent

The use of recycled concrete aggregates (RCA) instead of natural aggregates in hot-mix asphalt mixtures is one of the ways to achieve energy savings and reduce carbon emissions in road engineering. However, the cement mortar on the surface of RCA adversely affects the adhesion properties between asphalt and aggregates, leading to a reduction in the performance characteristics of asphalt mixtures. In this study, a silane coupling agent (SCA) was employed to improve the adhesion properties of the RCA/asphalt interface. The enhancement mechanism of SCA on the RCA/asphalt interface was investigated from multiple perspectives, including macroscopic properties, interfacial microstructure, and nanoscale interfacial interactions. Firstly, the adhesion behavior and tensile strength of the interface between RCA and asphalt were determined through a boiling water test and direct tensile test, both before and after SCA modification. Secondly, scanning electron microscopy (SEM) was employed to observe the surface microstructure of RCA and the microstructure of the RCA/asphalt interface. Finally, the main component of mortar, calcium silicate hydrate (C-S-H), was taken as the research subject of investigation to examine the hydrogen bonding, interaction energy, and interface transition zone of the C-S-H/asphalt interface system using the molecular dynamics methodology. The results demonstrate a two-level enhancement in the adhesion performance of the interface at the macroscopic scale following SCA modification. The interface tensile strength increased by 72.2% and 119.7% under dry and wet conditions, respectively. At the microscopic scale, it was observed that the surface pores of RCA were repaired after SCA modification, resulting in a more tightly bonded interface between the RCA and asphalt. At the nanoscale, SCA modification reduces the hydrophilicity of the C-S-H surface, increases the interaction energy and water resistance of the C-S-H/asphalt interface, and enhances the weak interface transition zone between C-S-H and asphalt. This study provides a theoretical basis for using SCA to enhance the bond strength of the RCA/asphalt interface and lays the foundation for the application of RCA asphalt mixtures on highways.

Evaluation of the Adhesion between Aggregate and Asphalt Binder Based on Image Processing Techniques Considering Aggregate Characteristics.

Aggregate-asphalt adhesion plays an important role in the water stability of asphalt concrete. In various test standards of different countries, it is evaluated via the subjective judgment of testers using the boiling water test. The subjective judgment in the test method is detrimental to the accuracy of the adhesion evaluation. However, there is no quantitative evaluation method for the aggregate-asphalt adhesion in existing studies. Moreover, the effects of aggregate shape on adhesion are also not discussed and stipulated. Hence, an innovative method based on the Chinese boiling water test and image processing technique is put forward to quantificationally evaluate the aggregate-asphalt adhesion. Moreover, the effects of aggregate shapes on adhesion are also investigated via the proposed method from a view of aspect ratio and homogeneity. Results show that the peeling of the asphalt membrane on the aggregate surface is more serious as the complexity of the aggregate shape increases after the boiling water tests, while the effect degree gradually decreases. The effect of aspect ratio on the peeling status of asphalt membrane is lower than that of aggregate homogeneity.

Moisture sensitivity and heavy metal leaching potentials of asphalt mixtures incorporating rubber modifiers and wax-based admixture

Moisture damage is one of the most frequent damages that occurs on asphalt pavements. The application of rubberized materials for asphalt is widely acceptable due to cost saving and environmentally friendly. The purpose of this study is to assess the performance of rubberized asphalt mixtures containing wax-based admixture, namely Tough Fix Hyper (TFH), in terms of moisture sensitivity and hazardous compound leaching potential. The moisture absorption, chemical immersion, and boiling water tests were used to assess the resistance to moisture damage on aggregate-binder bonding characteristics. Following that, the trend of moisture sensitivity was evaluated through an image analysis procedure. To simulate the environmental impact of leaching, the toxicity characterization leaching procedure (TCLP) test was adopted. The results showed that interaction between the crumb rubber or latex with TFH decreases the stripping value of the mixes significantly based on the chemical immersion test. Furthermore, the image analysis of the samples subjected to boiling water conditioning showed that pixels of asphalt samples without TFH, ranging from 524,949 to 472,346, decrease from 520,870 to 289,070, indicating that the asphalt remained coated area improved by 67.70–91.39%. The analysis of the leachate test revealed that the heavy metals, including arsenic (As), nickel (Ni), copper (Cu), chromium (Cr), vanadium (V), and cadmium (Cd), were not detected. However, zinc (Zn) was detected in the modified mixture, ranging from 0.05 to 0.114 mg/L, which lies within the allowable norm. In conclusion, the incorporation of crumb rubber and TFH in asphalt mixtures poses no environmental risk.

Mosses on Geopolymers: Preliminary Durability Study and Chemical Characterization of Metakaolin-Based Geopolymers Filled with Wood Ash.

Burning wood is estimated to produce about 6-10% of ash. Despite the possibility of recycling wood ash (WA), approximately 70% of the wood ash generated is landfilled, causing costs as well as environmental pollution. This study aims to recycle WA in an alternative way by inserting it as filler in geopolymeric materials. Here, metakaolin, NaOH, sodium silicate, and WA are used to realize geopolymers. Geopolymers without and with 10, 20 and 30% of WA are synthesized and characterized after 7, 14, 28 and 56 days. The article's study methods are related to geopolymers' chemical, biological and mechanical properties. The geopolymers synthesized are compact and solid. The pH and conductivity tests and the integrity and weight loss tests have demonstrated the stability of materials. The FT-IR study and boiling water test have confirmed the successful geopolymerization in all samples. The antibacterial analysis, the moss growing test and the compressive strength test have given a first idea about the durability of the materials synthesized. Furthermore, the compressive strength test result has allowed the comparison from the literature of the specimens obtained with the Portland cement (PC). The results obtained bode well for the future of this material.

Chemical upcycling of waste PET into sustainable asphalt pavement containing recycled concrete aggregates: Insight into moisture-induced damage

Waste polyethylene terephthalate (PET) plastic and construction and demolition waste are main municipal solid wastes. If they are not properly disposed of, they will cause continuous damage to the ecological environment. Previous studies have shown that recycled concrete aggregate (RCA) can be successfully adopted to replace natural aggregate (NA) for asphalt pavement construction. However, the moisture-induced damage, as one of the pavement engineering performances, is very prominent for asphalt concrete containing RCA (RCA-AC), due to the high absorption of RCA and the weakness of the adhered mortar. Given this, PET additive, derived from waste bottle bodies, is considered to improve the resistance of RCA-AC to moisture-induced damage in this study, which has been previously identified effective to enhance the anti-stripping characteristics of asphalt mixtures containing NA. To achieve this goal, this study applied a series of tests including contact angle, image recognition, boiling water test, immersed Marshall test, freeze–thaw (F-T) splitting test, wheel tracking test, and field emission scanning electron microscope (FESEM) to evaluate the moisture-induced damage of RCA-AC containing PET additive. The results showed that PET additive has a significant ability to improve the bonding strength and adhesion of asphalt binder to RCA and reduce the stripping percentage and moisture-induced susceptibility of RCA-AC, especially under the F-T cycles. In addition, the 60 °C rut deformation resistance of RCA-AC after immersion can be improved as the PET additive is used. Furthermore, the interfacial bonding layers (IBL) of PET additive modified asphalt binder between RCA particles are still existent and its width is not significantly increased after immersion and F-T cycles by contrast to that of virgin binder. In general, the appropriate use of PET additive is a good approach to promote the high-quality recycling of RCA into sustainable asphalt pavement.

Optimization of surface free energy parameters for asphalt binder-aggregate system based on RBF neural network model

Asphalt pavement is subject to water damage frequently, which reduces the level of service that it provides and contributes to many road diseases. The surface free energy (SFE) theory has proven to be a trustworthy approach to assess water damage in asphalt mixtures. The goal of this investigation was to optimize the SFE parameters of asphalt binder-aggregate systems using an RBF neural network model. In this research, the SFE parameters of asphalt binder-aggregate systems were calculated firstly. Then, the modified boiling water test and the immersion Marshall test, as well as the freeze–thaw splitting test were then used to assess the asphalt mixtures’ adhesive properties and water stability. Thereafter, the comprehensive analysis method of entropy weight was used to conduct a thorough evaluation of the asphalt mixtures’ resistance to water damage. Next, the comprehensive evaluation index, Wi, of the asphalt mixtures’ resistance to water damage was used as the output layer of the RBF neural network model to optimize the SFE parameters. Finally, the feasibility of the optimized the SFE parameters using RBF neural network model was verified by establishing the connection between the optimized SFE parameters and the asphalt mixtures’ resistance to water damage by the entropy weight comprehensive analysis method. The results showed that among the SFE parameters of asphalt binder-aggregate systems optimized using the RBF neural network model, the Lewis base component and the Lifshitz nonpolar component of the aggregate played a dominant role in the ability to resist water damage, followed by the VDW adhesion work and the VDW de-bonding work formed by van der Waals forces. Furthermore, the asphalt binder-aggregate system composed of limestone had the best adhesion properties among all aggregates.

Measuring moisture damage of hot-mix asphalt (HMA) by digital imaging-assisted modified boiling test (ASTM D3625): Recent advancements and further investigation

Boiling water test (ASTM D3626) has been utilized to investigate the moisture susceptibility of asphalt mixture for decades. It was originally intended to compare the relative moisture resistance of a few mixtures, and the degree of stripping after the boiling was recorded based on visual observations. In recent years, several digital imaging-assisted modified boiling tests have been proposed, which significantly improved the accuracy of test results. This paper reviewed the recent advancements (2009–2022) in different test methods by digital imaging. The limitations and challenges of each method were also discussed and compared to each other. In addition, further experiments were performed to investigate the effect of aging, boiling time and water quality on the coating ratios. The boiling test results of sixty loose mixtures were compared to the tensile strength ratios (TSRs). Based on the results, the boiling water test with enhanced accuracy by image processing can be potentially developed as a measure of field performance. More importantly, the test should be conducted immediately after the mixing of asphalt and aggregate, and the aging of asphalt mixtures could significantly increase the results of coating ratios up to 100%, which made the boiling test unable to identify moisture susceptibility. It was found that the boiling water could not strip asphalt from aggregate after a long time of aging even though the moisture damage occurred and weakened the bond between asphalt and aggregate. In addition, the water quality could considerably influence the boiling test results, and the use of distilled water might underestimate the moisture damage of asphalt mixtures subjected to acid rain.

Moisture Damage Assessment of Asphalt Mixture using Eatons Reagent

Abstract: The main purpose of this research work was to create a correlation model called a moisture damage index, that could predict moisture damage probability in both qualitative and quantitative test regimes. To determine the effect on moisture damage of asphalt mixture, chemical-based modifiers and single aggregate sources, such as calcium carbonate, were selected. Eaton's Reagent, i.e., Phosphorous Pentoxide in Methane Sulphonic Acid, is used to make modified bitumen in this research. Eaton's Reagent is made in a laboratory with a 1:10 synthesis formula and a unique technique. Base binders are changed with varied amounts of Phosphorus Methyl Compound (PMC) by weight of optimum binder content i-e 0.25%, 0.50%, 0.75% & 1.00%. To establish a moisture damage index, the dosage of Eaton's Reagent was optimised using both qualitative and quantitative measurements. This reagent interacts strongly with the asphaltene fraction of bitumen rather than the maltenes portion, resulting in a higher service temperature than the base binder. Asphalt mixtures were prepared and tested using performance testing to verify the effect of phosphorous methyl compound on their performance. The boiling water test was simple to administer and took less time, while the rolling bottle test was found to be more reliable than other qualitative tests. Although Marshal stability was easy to perform in quantitative tests, while the Hamburg wheel track test were shown to be more effective in determining moisture susceptibility with a reasonable level of confidence. A testing regime compromises of qualitative as well as quantitative tests to ascertain relative accuracy of each test on moisture damage. Keywords: Eaton’s Reagent; Asphalt mixtures; Loss of adhesion; moisture damage; limestone

Influence of novel long-chain active composite rejuvenators on interfacial adhesion between aged SBS modified asphalt and aggregate

In this study, the novel long-chain active composite rejuvenators (NLCACRs) were composed of long-chain active rejuvenators (LCARs) and aromatic hydrocarbon oil (ArO). Surface free energy method (SFE method), boiling water test method (BWT method) and related parameters were used to evaluate the effect of NLCACRs on interfacial adhesion between aged SBS modified asphalt (ASBS-MA) and granite, and preliminarily predict the moisture sensitivity of asphalt-aggregate system. The results indicated that NLCACRs could increase the surface free energy of ASBS-MA, and the increased range varied with the composition and structure of NLCACRs. The NLCACRs could not only supplement the light components lost by asphalt during aging, but also reconstruct the damaged structure of aged SBS, so they were more effective for the recovery of cohesion work of ASBS-MA. NLCACRs could significantly increase the interfacial adhesion between ASBS-MA and acid granite, and decrease the moisture sensitivity of rejuvenated SBS modified asphalt (RSBS-MA)-granite system. And the results of the BWT method indicated that long-term aging decreased the adhesion grade between SBS modified asphalt and granite from G4 to G2. NLCACRs could restore the adhesion grade of ASBS-MA and granite to the level of original SBS modified asphalt. The comprehensive analysis of the influence of NLCACRs on the interfacial adhesion between ASBS-MA and aggregate showed that the theoretical law (SFE method) was consistent with that of the actual (BWT method). This study could help to explore the influence of NLCACRs on the moisture stability of aged SBS modified asphalt mixture and provide the theoretical basis for its application in practical engineering.

Lignin-Glyoxal: A Fully Biobased Formaldehyde-Free Wood Adhesive for Interior Engineered Wood Products

In this study, a biobased phenolic adhesive was successfully developed by entirely substituting both petroleum-based phenol and formaldehyde with an unmodified corn stover biorefinery lignin and glyoxal (a biobased dialdehyde), respectively. Lignin-glyoxal resins were synthesized using an alkaline catalyst with a molar ratio of lignin to glyoxal of 1:2. Chemical, thermal, and mechanical properties of the lignin, lignin-based resins, and final adhesives were assessed following appropriate standard test methods. The analysis of lignins and lignin-based resin molar mass was performed using gel permeation chromatography. The lignin-glyoxal resin was found to have a 3-fold higher average molecular weight than the starting lignin, demonstrating the successful integration of lignin into the polymeric resin network. The curing of the formulated adhesives was studied using differential scanning calorimetry and dynamic mechanical analysis. Although the lignin-glyoxal resin had a higher curing temperature (167 °C) than a conventional phenol-formaldehyde resin (142 °C) and the formulated lignin-formaldehyde resin (146 °C), the rate and degree of cure were similar or better than the other two resins. The adhesion strengths of the formulated adhesives were determined using single-lap-joint veneer samples cured according to recommended press parameters for commercial adhesives. The lignin-glyoxal adhesive had a relatively high dry adhesion strength (3.9 MPa), with over 90% wood failure, but failed the wet adhesion test (boiling water test). Although the formulated lignin-glyoxal adhesive failed the boiling water test, it had excellent stability at room temperature water, remaining intact after 1 week during the water immersion test. The high dry adhesion strength makes this class of lignin-based formaldehyde-free adhesives a unique biobased glue for the production of interior grade plywood and oriented strand boards.

Evaluation of engineering properties of Fiber-reinforced Usual-temperature Synthetic Pitch (USP) modified cold mix patching asphalt

As a common-used pothole repairing material, cold mix patching asphalt (CMA) has been widely used in practice. This article aims to develop a novel CMA with good overall performance and better environmental-friendliness. A few environmental-friendly ingredients, including a modifier named Usual-temperature Synthetic Pitch (USP), polyester-basalt composite fibers, a commercial anti-stripping agent, a commercial tackifier and biodiesel, were utilized for preparing Fiber-reinforced USP modified CMAs (FUAs). Laboratory tests, including workability assessment tests, Marshall stability tests, boiling water tests, rolling sieve cohesion tests, freeze-thaw splitting tests, wheel tracking tests and three-point bending tests, etc. were conducted to evaluate the workability, Marshall stability, adhesion, moisture susceptibility, rutting resistance, bending resistance and storage stability. Two mix designs of the cutback (termed as Scheme 1 and 2) with weight ratios of 100:6:18:0.3:0.6 and 100:6:20:0.4:0.8 for binder: USP: biodiesel: anti-stripping agent: tackifier were considered. Effect of fiber content (0.2%, 0.3%, 0.4% and 0.5% by aggregate weight) was also investigated considering an optimal polyester to basalt fiber weight ratio of 3:2. The results show that the optimal fiber content is 0.4%. The engineering properties of FUAs meet the construction requirements, and they also present good storage stability. Scheme 2-based cutback shows better workability, smaller penetration and better binder-aggregate adhesion than the Scheme 1-based cutback; consequently, the Scheme 2-based FUA presents advantages over Marshall stability, rutting resistance and bending resistance. Compared with Styrene-Butadiene-Styrene (SBS) modified CMAs, FUAs possess better overall performance and advantages over environmental conservation. The FUAs, therefore, have good application prospects in pavement repair.

Effect of Cement and Fly Ash Dosages on the Characteristics and Performance of Microsurfacing Mix

In this study, the role of mineral fillers on the microsurfacing mix characteristics and performance was assessed for 10 different combinations of mineral filler type (cement and fly ash) and dosages (0%–3%). The mixes were initially characterized in terms of compatibility, cohesion, and adhesion using Schulze-Breuer and Ruck test, cohesion test, and boiling water test, respectively. Subsequently, the performance of microsurfacing mixes, that is, raveling and rutting resistance, was determined using wet track abrasion test and loaded wheel test, respectively. Results indicated that the filler–emulsion system’s compatibility improved significantly with the addition of cement at the proper dosage. In contrast, mixes with only fly ash as mineral filler had inferior filler–emulsion compatibility. Also, the rate of strength development and adhesion was higher with cement than fly ash. The performance, that is, raveling and rutting resistance, positively correlates with the 60-min cohesion, adhesion, and compatibility (abrasion loss). Interestingly, the combination with 2% cement and 1% fly ash as mineral filler had the best mix characteristic and performance, indicating that the careful selection of the type and the dosage of mineral filler could maximize the durability of the microsurfacing mix.