Permanent Deformation Resistance Research Articles

Mechanical strength of an hot-mix asphalt using recycled concrete aggregate: mass and volume proportioning

The generation of solid waste produced by the construction sector is considered a major problem worldwide. Several studies have been conducted to evaluate the use of construction and demolition wastes (CDW) in pavements. Within CDW, one material with great potential for use is recycled concrete aggregate (RCA). The present study evaluated the mechanical performance of a hot-mix asphalt (HMA) that used RCA as a partial substitute for the coarse fraction of the natural aggregate – Nag (particle size retained on 1/2” and 1/2"+3/8” sieves). The substitution was performed in a conventional way by mass and also by volume. To evaluate the performance under monotonic loading, the stability/flow ratio (S/F) of the Marshall test and the Indirect Tensile Strength (ITS) were measured on dry (ITSd) and conditioned (immersed in water, ITSw) samples. The tensile strength ratio (TSR) was calculated to evaluate the resistance to moisture damage. Under cyclic loading, tests of resilient modulus – RM (three temperatures and three loading frequencies), permanent deformation, and fatigue resistance under controlled-stress were performed. Cantabro tests were performed to measure the resistance to abrasive wear. Conventional characterization tests and imaging processing in a scanning electron microscope (SEM) were carried out on particles of RCA and Nag. A Life Cycle Cost Analysis (LCCA) was performed with the results obtained. The general conclusions were as follows: (i) RCA increases the asphalt content in the mixes, however, volume substitution could help to decrease it; (ii) the mixes with RCA met the volumetric and strength parameters established by the Colombian specification (especially for roads with low traffic volumes); (iii) mixes with RCA undergo better mechanical performance in all tests performed, however, resistance to moisture damage may be compromised when dosing by volume and asphalt content decreases; (iv) substitution by mass or volume did not generate clear trends in the results, but better overall performance is reported in mixes dosed by volume. It is recommended to carry out more studies where Nag is replaced by RCA in volume.

Performance Evaluation and Modification Mechanism Analysis of High-Viscosity Modified Asphalt

Abstract High-viscosity modified asphalt (HVMA) has important application potential in pavement engineering, such as porous asphalt pavements and ultrathin overlays. To comprehensively study and evaluate the overall performance of HVMA, five HVMA samples were prepared using modifier with dosages of 6 %, 9 %, 12 %, 15 %, and 18 %, respectively. The basic physical properties of HVMA were evaluated according to standard physical asphalt performance tests. The overall rheological properties of HVMA were assessed using temperature sweep tests, frequency sweep tests, and multiple stress creep recovery tests. Fluorescence microscopy was employed to analyze the microscopic characteristics and the modification mechanism of HVMA. The results show that the high-viscosity modifier could improve the overall rheological properties of HVMA at both high and low temperatures, with approximately 9 % determined as the optimal dosage. HVMA had better performance than matrix asphalt in high-temperature rutting resistance, permanent deformation resistance, temperature sensitivity, and elastic characteristics. At an appropriate dosage of the high-viscosity modifier, the modifier absorbed the light components in the asphalt, causing them to swell and dissolve. As a result, the modifier could be uniformly dispersed in the asphalt, thereby significantly improving the high-temperature stability of HVMA. The results of this paper may be helpful to the mechanism research and application of HVMA.

Research on Low-Cost High-Viscosity Asphalt and Its Performance for Porous Asphalt Pavement.

To develop a cost-effective, high-viscosity asphalt for porous asphalt pavement, we utilized SBS, tackifier, and solubilizer as the main raw materials, identified the optimal composition through an orthogonal experiment of three factors and three levels, and prepared a low-cost high-viscosity asphalt. We compared its conventional and rheological properties against those of rubber asphalt, SBS modified asphalt, and matrix asphalt, employing fluorescence microscopy and Fourier transform infrared spectroscopy for microstructural analysis. The results indicate that the optimal formula composition for high-viscosity asphalt was 4-5% styrene-butadiene-styrene (SBS) + 1-2% tackifier +0-3% solubilizer +0.15% stabilizer. The components evenly dispersed and the performances were enhanced with chemical and physical modification. Compared with SBS modified asphalt, rubber asphalt, and matrix asphalt, the softening point, 5 °C ductility, and 60 °C dynamic viscosity of high-viscosity asphalt were significantly improved, while the 175 °C Brookfield viscosity was equivalent to SBS modified asphalt. In particular, the 60 °C dynamic viscosity reaches 383,180 Pa·s. Rheological tests indicate that the high- and low-temperature grade of high-viscosity asphalt reaches 88-18 °C, and that high-viscosity asphalt has the best high-temperature resistance to permanent deformation and low-temperature resistance to cracking. It can save about 30% cost compared to commercially available high-viscosity asphalt, which is conducive to the promotion and application of porous asphalt pavement.

The Performance of Modified Asphalt Mixtures with Different Lengths of Glass Fiber

AbstractOne practical option for modifying an asphalt mixture’s performance is to use additives. This will help the mixture perform better against the damaging effects of traffic, loads, and climatic variations. In this regard, glass fiber (GF) has drawn much interest because of its positive effect. Therefore, this paper attempts to study the effect of glass fiber length and content on the performance and strength of asphalt mixtures. It also aims to determine the optimum glass fiber content and the best glass fiber length of modified asphalt mixtures. An experimental program is carried out, which includes the Marshall test, volumetric properties, freeze-thaw splitting test, immersion Marshall test, and wheel tracking test to characterize related properties of glass fiber incorporated in asphalt mixtures. Seven different percentages (0, 0.25, 0.5, 0.75, 1, 1.25, and 1.5) of glass fiber by total weight of aggregates in three various lengths are used to design 19 asphalt mixtures. Based on the results obtained, the performance of the asphalt mixture was enhanced remarkably after adding glass fiber. The use of various lengths of glass fiber led to a better-quality asphalt mixture in terms of volumetric properties, moisture damage resistance, and permanent deformation resistance. Specifically, asphalt mixtures made with (0.5%) glass fiber illustrated the highest quality, and adding (20 mm) length of glass fiber was better than (10 mm and 30 mm) glass fiber lengths. The results also show that adding (10 mm and 30 mm) lengths of glass fiber can improve the resistance of asphalt mixtures to water damage and permanent deformation compared with the control mixture (M0). The findings indicate the applicability of 20 mm glass fiber length in asphalt mixtures to achieve better resistance against moisture and reduce the chance of irreparable permanent deformation under growing traffic loads and hot climate changes. Although the inclusion of glass fiber in asphalt mixtures led to a modest increase (6%) in overall cost, the effective improvement in performance and extension of the service life of the asphalt pavement constitute a convincing argument for this approach, making it an attractive option. Finally, it was concluded that a higher amount of glass fiber (i.e., > 0.5%) and a length greater than (20 mm) could diminish the positive effect of glass fiber to improve the properties of glass fiber asphalt mixtures.

Tuning high- and low-temperature rheological properties of warm-mixing asphalt composites by functionalized waxes

Traditional asphalt road construction utilizes hot-mixing asphalt mixtures. High temperatures not only accelerate the aging of asphalt, but also produce large amounts of toxic and greenhouse gases. To alleviate these problems, wax-based warm-mixing agents are applied, and asphalt pavement construction temperatures can be efficiently lowered, resulting in lower energy and gas emissions. To systematically evaluate the effects of composition and structure of warm-mixing agents on rheological properties of asphalt at high and low temperatures, a series of functionalized waxes (i.e., oxygen-containing groups, amide groups, and long-chain aliphatic hydrocarbons) were designed in this work, followed by a melt-mixing process with asphalt. The findings demonstrated that warm-mixing agents with long-chain aliphatic hydrocarbons could significantly improve asphalt composites’ rheological properties at high temperatures, such as good viscosity-reducing effect and superior rutting resistance or permanent deformation resistance; warm-mixing agents with oxygen groups were able to improve the asphalt composites’ resistance to low-temperature cracking; amide group-containing warm-mixing agents could improve the surface roughness of asphalt composites. This work provides a practical guide for the selection of functionalized warm-mixing agents for asphalt pavement under multiple environmental factors.

Evaluation of asphalt binder and mixture properties utilizing fish scale powder as a biomodifier

Fish represents an abundant and underutilized waste product from the fishing industry. This study investigated the effects of incorporating fish scale powder (FSP) at various dosages (3%, 6%, 9%, and 12%) on the properties of asphalt binder and mixtures. Conventional tests, viscosity, storage stability, Fourier transform infrared spectroscopy, and multiple stress creep recovery tests were conducted on the binder. Mix design, wheel tracking, indirect tensile strength, fatigue, and ultrasonic pulse velocity tests were evaluated for the asphalt mixtures. The results showed that FSP increased the binder’s stiffness and reduced the temperature susceptibility but compromised the low-temperature performance and workability regardless of the dosages. The storage stability test results demonstrated the improved high-temperature storage stability. In the mixtures, the permanent deformation resistance enhanced with increasing the FSP content, decreasing the rut depth from 4.3 mm for the control sample to 2.9 mm at 12% FSP. The moisture damage resistance, indicated by the tensile strength ratio, increased from 90% for the control sample to 94.1% at 12% FSP. However, the fatigue life decreased from 14010 cycles for the control sample to 11190 cycles at 12% FSP. The dynamic and elastic modulus values before conditioning increased with higher FSP dosages, and this increasing trend was also observed after conditioning, signifying greater stiffness retention and moisture resistance of the asphalt mixtures containing higher amounts of FSP. Numerically, the 6–9% FSP range offered the optimum balance, improving the rutting resistance by 18% and the moisture resistance by 3.2% compared to those of the control sample, while limiting the fatigue life to 12% and maintaining the workability. Overall, FSP has potential for use as an asphalt biomodifier by transforming an environmental liability into a value-added sustainable paving material.

Full-scale experimental investigation on the performance of seamless asphalt plug joint through mixture design and structural enhancements

The seamless asphalt plug expansion joint integrates a traditional asphalt plug joint (APJ) with an overlying continuous asphalt concrete layer, preventing block failure of the asphalt plug joint and enhancing driving comfort. However, typical damages such as fatigue cracking, rutting, and permanent deformation often occur in the upper asphalt layer. This is attributed to the inadequate stiffness of the lower joint plug mastic, particularly under high temperatures and heavy loads. To extend the service life of asphalt plug expansion joints under such conditions and enhance their durability, efforts were made to bolster the performance of the lower asphalt plug joint mixture and improve anti-rutting performance. This study involved: (1) Qualifying APJ mixture requirements under high temperature and heavy load by focusing on two critical material properties: good rutting resistance and permanent deformation resistance. High temperature rheological properties of these binders were examined through temperature scanning tests and multi-stress creep recovery tests (MSCR). (2) Exploring the impact of binder-aggregate ratios and specimen molding methods (standard compaction, paving vibration and pre-mixing) on the bonding strength and rutting resistance of the APJ mixture. This analysis was conducted using pull-off tests and dynamic stability tests. (3) Development of a novel APJ featuring dowel bars to enhance vertical deflection resistance and joint horizontal movement. Comprehensive laboratory tests showcased the modified joint structure's resilience after numerous test cycles, demonstrating exceptional resistance to bending and vertical deformation. The significant findings from this research provide valuable insights for optimal material selection, appropriate joint design, and installation guidelines for seamless asphalt plug expansion joints.

The Effect of Nano-Hydrated Lime on the Durability of Hot Mix Asphalt

Recently, some of Iraq's newly constructed asphalt concrete pavements showed premature failures with significant negative impacts on roadway safety and the economy. Using Nano hydrated lime (NHL) in pavement construction could be one of the possible steps to improve pavement durability. This article discusses how NHL affects the durability of hot mix asphalt. NHL was added in two methods to the asphalt concrete mixture for the wearing course. The first is the dry method, i.e., on the aggregate, whereas the second is the wet addition method, i.e., to the bitumen. The percentages were tried for each additional method; 1, 2, and 3% by weight of aggregate for the dry method and 0.5, 1, and 1.5% by weight of asphalt concrete for the wet method. The optimum asphalt cement contents were evaluated using the Marshall procedure. Asphalt concrete mixes were prepared at their optimum asphalt content and then tested to evaluate their durability properties, including moisture damage and permanent deformation. These properties have been evaluated using indirect tensile strength and uniaxial repeated loading tests. The results show that the NHL has improved the permanent deformation characteristics and resistance to moisture susceptibility.

Self-healing performance and rheological properties of styrene-butadiene-styrene block copolymer modified asphalt promoted by polyurea elastomers containing disulfide bonds

Self-healing asphalt is considered as one of the desirable methods to extend the service life of asphalt pavement. This research prepared a polyurea elastomer containing dynamic disulfide bonds (PUA)/styrene butadiene styrene block copolymer (SBS) composite modified asphalt. Moreover, a new asphalt self-healing performance evaluation method based on the damage process and results has been proposed. Subsequently, the self-healing ability of PUA, the distribution of modifier, the functional group and molecular weight of composite modified asphalt were characterized by fluorescence microscope, Fourier transform infrared spectroscopy (FTIR) and Gel permeation chromatography (GPC). The self-healing potential and limits of PUA/SBS composite modified asphalt was investigated through the proposed healing linear amplitude scanning (HLAS) test. Results show that the SBS content and fatigue load level are the main factors affecting the self-healing promotion effect of PUA. The critical point of healing fatigue strain (HFS) can indirectly characterize the threshold at which healing promoters exert their effects. Next, the addition of fillers will reduce the self-healing performance of PUA/SBS composite modified asphalt, but it still improves by at least 61.318% compared with SBS modified asphalt. Finally, the addition of self-healing elastomers (PUA) improves the permanent deformation resistance at high temperature and low-temperature crack resistance of SBS modified asphalt. The dynamic recombination of disulfide bonds can increase the fatigue cycle number of 4%SBS modified asphalt by 93.52% at a 5% load strain level.

Uni- and tri-axial tests and property characterization for thermomechanical effect on hydrated lime modified asphalt concrete

Permanent deformation, fatigue and thermal cracking are the three typical distresses of flexible pavement. Using hydrated lime (HL) into the conventional limestone mineral additive has been widely practiced, including in Europe, to improve the mechanical properties of hot mix asphalt (HMA) concrete and as the result the durability of the constructed pavement. Large number of experimental studies have been reported to find the optimum addition of HL for the improvement on HMA concrete mechanical properties, moisture susceptibility and fatigue resistance. Pavement in service is under complex thermomechanical stress-strain conditions due to coupled atmospheric and surrounding environment temperature variation and the traffic loading. To predict and analyse the performance of pavement structures the data only from uniaxial compressive test for the resilient modulus and permanent deformation would be not enough. However, so far, the data of HL modified HMA concrete under complex loading conditions are still not well informatively complete. To contribute new knowledge, this paper reports an experimental study of both uni- and tri-axial tests for the asphalt concrete using HL into mineral additive for the mixes designed for the applications of wearing, levelling, and base layers, respectively. All the tests were conducted under three controlled temperatures and four stress deviations. The test results have showed that, for all three types of mixes, the permanent deformation of the HL mixes is less than the ones of no HL addition. The degree of the improvement on permanent deformation resistance using HL is much pronounced at high stress deviation states. The results have also showed that the resilient modulus strongly depends on the temperature and stress deviation while the mixes of HL addition demonstrate higher rigidity. At last, mathematical characterization models have been proposed for the measured material properties. A numerical simulation case study has been performed to test and demonstrate the application of the proposed unified property model.

Experimental Investigation of Polymer and Nanomaterial modified Asphalt Binder

Modifying the asphalt binder and mixture becomes one of the best ways to mitigate pavement distress and increase the service life of constructed road networks. This study aimed to evaluate the influence of modified asphalt binders with the best different percentages of polymer and nanoparticles. Typical asphalt binder (penetration, softening point, and viscosity) and frequency sweep tests were used to evaluate the physical and rheological properties of modified asphalt binders with 5% Acrylonitrile Styrene Acrylate (ASA), 5% aluminum oxide nanoparticles (Al2O3), and 5% calcium carbonate (CaCO3). The results showed that the physical properties of all modified blends improved compared to those of the base asphalt binder. The improvement in softening point was up to 19%, the penetration reduction was nearly 69%, and the sensitivity to elevated temperatures was reduced by up to 13%. Evaluation of the rheological properties showed that modified asphalt with 5% Al2O3 binder had the highest permanent deformation resistance, followed by 5% ASA. The 5% CaCO3 binder showed a small improvement compared to the other samples. The results showed that the 5% Al2O3 binder had the highest complex modulus and the lowest phase angle, which means that it has the best viscoelastic properties. Therefore, it can be recognized as the best asphalt binder among the modified binders in this study.

Experimental study on the effect of Coumarone resin on the performance of SBS-modified asphalt.

An inexpensive and high-performing solid Coumarone resin was added to Styrene-butadiene-styrene (SBS) copolymer-modified asphalt to enhance its storage stability and road performance. To assess the effect of Coumarone resin dosage on the SBS-modified asphalt, a series of laboratory tests were conducted. The composite modified asphalt's segregation test was used to evaluate its storage stability, Dynamic Shear Rheometer (DSR) and Multiple Stress Creep Recovery (MSCR) tests were employed to investigate its high-temperature performance and permanent deformation resistance, and the Bending Beam Rheology (BBR) test was utilized to measure its low-temperature performance. Fluorescence microscopy was used to observe the composite modified asphalt's microstructure, and Fourier Transform Infrared Spectroscopy (FTIR) was conducted to study the changes in chemical structure during the modification process. The results showed that Coumarone resin can improve the compatibility of SBS and asphalt, improve the high-temperature performance and deformation resistance of SBS-modified asphalt, and adding an appropriate amount of Coumarone resin can help enhance the low-temperature cracking resistance of modified asphalt. The optimal dosage of Coumarone resin recommended for SBS-modified asphalt performance enhancement is 2% under the test conditions, as determined by comparing the test results of samples with various dosages.

Effect of Replacement of Limestone Mineral Powder with Fly Ash and Direct Coal Liquefaction Residue on the Rheological Properties of Asphalt Mastic

Fly ash (FA) and direct coal liquefaction residue (DCLR) are coal-based industrial solid waste. Their unreasonable disposal has brought enormous economic, resource and environmental pressures. An effective treatment method is urgently needed. This study used FA and DCLR as fillers to replace limestone mineral powder (LP). The rheological properties of their corresponding asphalt mastics were evaluated by conventional performance tests and DSR tests. The effect of different properties of fillers on the rheological properties of mastic was revealed through finite element simulation. The test results show that FA and DCLR improve the viscosity, rutting resistance, elasticity and permanent deformation resistance of asphalt mastic, and reduce the temperature sensitivity. The improvement effect of FA is the most significant. The simulation results show that particle size and shape of filler affect the rheological properties and temperature sensitivity of asphalt mastic to different degrees respectively, and the filler particle size is the dominant factor.

Incorporating Environmental Impact Analysis into Louisiana’s Balanced Asphalt Mixture Design

To meet the asphalt pavement industry’s net zero carbon emission goals, increasing reclaimed asphalt pavement (RAP) levels to greater than 25% is considered a critical tactic. However, many state departments of transportation are cautious in adopting high RAP content into their designs because of durability issues resulting from aged RAP binders. This paper assesses the effectiveness of using the Lewis acid catalyst, FeCl3, in improving the cracking resistance of high-RAP asphalt mixtures to meet Louisiana’s balanced mixture design (BMD) criteria, and lower embodied carbon of asphalt mixtures. Four asphalt mixtures were designed and tested against permanent deformation, intermediate- and low-temperature cracking, and durability. Mixture 1 is conventional, which contains performance grade (PG) 76-22 polymer-modified asphalt binder with no RAP. Mixture 2 is unmodified PG 67-22 and 30% RAP without catalyst. Mixtures 3 and 4 incorporated an unmodified asphalt binder PG 67-22, a catalyst, and 30% and 50% RAP, respectively. A life cycle assessment (LCA) analysis was conducted on asphalt mixtures that complied with Louisiana’s BMD specifications to quantify global warming potential improvements. Because the performance of both mixtures is expected to be similar, the scope of the LCA analysis was limited to only those life cycle stages that are expected to be different, modules A1–A3 (i.e., cradle-to-gate stages). Results showed that the use of FeCl3 can improve asphalt mixtures’ cracking resistance containing high RAP contents, whilst it did not have a negative impact on permanent deformation resistance. Further, the addition of FeCl3 to asphalt mixtures with 30% and 50% RAP levels showed a reduction in greenhouse gas emissions by 28% and 43.4%, respectively.

Red mud application as filler in asphalt mixtures production

Red mud is the solid waste from bauxite processing during aluminium production. Its inadequate disposal causes social, economic and environmental prejudices. The industrial solid waste insertion evaluation in the production chain is beneficial and necessary. This work aims to evaluate the mechanical performance of asphalt mixtures produced with red mud as filling material. Asphalt mixtures with 5% and 7% red mud were produced, and permanent deformation and moisture-induced damage tests were carried out. A mixture without red mud addition (control) was produced for comparison. The results showed that the mixtures with red mud presented permanent deformation resistance greater than the control one, with more than 40% reduction in rutting deformation. The moisture damage did not significantly affect the mixtures tested. The red mud application as a filler in asphalt mixtures is viable and can be an alternative to reduce the damage such a waste can cause to the environment.

Evaluation of Properties of Asphalt Concrete Mixture Using Basalt Aggregate from Jeju Island

In this study, the engineering properties of basalt aggregate used for asphalt road pavement on Jeju Island were evaluated, and the characteristics of the asphalt mixtures used were evaluated to assess the suitability of Jeju Island basalt as road construction material. Chemical composition and surface morphology analysis of the basalt and granite aggregate, engineering characteristics analysis, and filler property evaluation were performed. Mix design was performed, and the basic properties of three asphalt mixtures for the surface, intermediate, and base layers were evaluated. Permanent deformation resistance was evaluated through a wheel tracking test, and moisture resistance was evaluated through a dynamic immersion test and a tensile strength ratio test. The optimum asphalt contents of the asphalt mixture using low-porosity basalt aggregate and high-porosity basalt aggregate were determined to be 5.7% and 5.9% in the surface layer, 5.3% and 5.4% in the intermediate layer, and 4.7% and 5.1% in the base layer, respectively. It was found that the basic properties of the asphalt mixtures satisfied Korean quality standards. The dynamic immersion test results of low-porosity basalt aggregate and high-porosity basalt aggregate were 20% and 10%, respectively, which fall far below the quality standard of 50%. The tensile strength ratios of the basalt asphalt mixtures for the intermediate layer were 0.69 and 0.40, and they were found to increase significantly to 0.87 and 0.80 after the application of a suitable anti-stripping agent. Therefore, it was concluded that in order to apply Jeju Island basalt to asphalt pavement, an appropriate anti-stripping material must be applied.

Life-cycle assessment of sustainable pavement based on the coordinated application of recycled asphalt pavement and solid waste: Environment and economy

To achieve efficient use of recycled asphalt pavement (RAP) produced during the maintenance and expansion of old roads and to solve the problem of low utilization of steel slag and desulfurization ash generated in the production process of the steel industry, this study designed a sustainable pavement using RAP and waste rubber powder-modified asphalt to form a matrix skeleton with large voids and injects grouting materials prepared with desulfurization ash and steel slag. It was found that the designed sustainable pavement has excellent high-temperature permanent deformation resistance and durability. Compared to traditional asphalt pavement, sustainable pavement's energy consumption and emissions can be reduced by about 45% within a single life cycle, while the economic benefits exceed about 500%. Moreover, sustainable pavement's excellent fatigue resistance will make its energy-saving, emission-reduction effects, and economic benefits more significant than traditional asphalt pavement during the same analysis period.

Performance Characterisation and Microscopic Characteristics of Rapeseed Heavy Oil–Diatomaceous Earth Composite-Modified Asphalt

In order to further improve the performance of bio-asphalt, because of its poor high-temperature performance, another biomass material, diatomaceous earth, was employed as a composite modifier, and a composite-modified asphalt was made to increase the high-temperature performance of bio-asphalt. The optimal preparation parameters of a rapeseed heavy oil–diatomaceous earth composite-modified asphalt were identified by employing an orthogonal test design. Based on the laboratory test, the physical properties, rheological properties, and microscopic properties of the asphalt were evaluated correspondingly by utilising matrix asphalt, rapeseed heavy oil-modified asphalt, and diatomaceous earth-modified asphalt as the control group. The results of the orthogonal test analysis showed that the optimum preparation parameters of the rapeseed heavy oil–diatomaceous earth composite-modified asphalt were 8% rapeseed heavy oil, 5% diatomaceous earth, a shear period of 35 min, and a shear rate of 2500 r/min. The addition of rapeseed heavy oil improved the fatigue resistance and low-temperature performance of the asphalt, but, at the same time, the asphalt penetration increased, the softening point and viscosity decreased, and the high-temperature rutting resistance decreased. Compared with the matrix asphalt, the viscosity of the rapeseed heavy oil–diatomaceous earth composite-modified asphalt at 135 °C rose by 23.2%. The rutting factor G*/sinδ increased by 45.5%, 15.6%, 17.6%, 29.8%, and 22.0%, while the fatigue factor G*·sinδ increased by 41.9%, 14.2%, 16.7%, 19.4%, and 23.1%, respectively, in the high-temperature rheological properties test temperature interval from 52 °C to 76 °C. The creep stiffness S fell by 16.2%, 36.1%, and 25.2%, while the creep rate m rose by 25.8%, 52.9%, and 13.4%, respectively, in the low-temperature rheological performance test temperature interval from −24 °C to −12 °C. Therefore, diatomaceous earth may effectively counteract the softening effect of the rapeseed heavy oil on the matrix asphalt and may raise the strength level and permanent deformation resistance of the composite-modified asphalt with only partial loss of fatigue resistance. The matrix asphalt, rapeseed oil, and diatomaceous earth exhibited high compatibility. The integration of rapeseed oil and diatomaceous earth largely did not modify the chemical properties of asphalt, and it was able to maintain the qualities of asphalt itself. Rapeseed heavy oil and diatomaceous earth on the thermal stability of the matrix asphalt has the opposite effect. The reorganisation component of diatomaceous earth on the colloidal structure of asphalt is conducive to the stabilisation of the nature of the asphalt, which can significantly improve the temperature stability of asphalt.

Laboratory evaluation of oak ash waste for use in hot mix asphalt modification

In this study, the effect of Oak Ash (OA), a biomass waste, on the mechanical properties of hot mix asphalt (HMA) was investigated and its usability in road engineering was evaluated. For this purpose, firstly, various physical and chemical properties of B70/100 penetration class pure asphalt, OA and crushed limestone aggregate were determined. Then, the optimum asphalt content (OAC) of the mixture was determined according to the Marshall mix design method using aggregate and pure asphalt. Based on this determined content, pure and OA added (1%, 2%, 4% and 6% by weight of asphalt) modified hot mix specimens were prepared. Pure and OA added modified mixture specimens were subjected to Marshall stability, indirect tensile strength (ITS), moisture damage, indirect tensile stiffness modulus (ITSM), static-dynamic creep and calorie tests. According to the results obtained, it has been determined that the OA additive has an improving effect on all mechanical properties of the mixtures, especially on the permanent deformation resistance at high temperatures. It is considered that the use of this additive at a rate of 2% in the hot mixture can increase the resistance of the pavement against deterioration and reduce the maintenance and repair costs of the road.

Approach for accurately characterizing nonlinear viscoelastic and nonrecoverable properties of asphalt binders based on MSCR test

The multiple stress creep and recovery (MSCR) test has been widely accepted as a more practical method for accessing the rutting performance of asphalt binders than the conventional Superpave rutting factor test. Nevertheless, there still exists a major concern that 9-s recovery time in each cycle may not guarantee a sufficient recovery of the recoverable viscoelastic strain, especially for modified asphalts, and this could result in a potential inaccuracy in characterizing rutting resistance of binders. To effectively separate the recoverable nonlinear viscoelastic (NLVE) and nonrecoverable responses in the MSCR test, this paper presents a new approach that adopts an additional one-cycle low-stress creep and recovery (LSCR) test and the Schapery’s NLVE model in analyzing the MSCR test data. The LSCR test, covering the entire duration of the MSCR test (200 s), can well determine the linear viscoelastic (LVE) recoverable properties that the Schapery’s model requires for NLVE analysis. The results show that with the recoverable and nonrecoverable responses accurately isolated, the proposed approach rigorously redefines the indicators of the percent recovery R and nonrecoverable creep compliance Jnr in the MSCR test, and therefore effectively eliminates the inaccuracy of the original indicators caused by incomplete recovery of the recoverable strain component in each cycle. Also, the developed method exactly characterizes stress dependence and permanent deformation resistance of asphalt binder, thus offering an effective and accurate approach for high-temperature performance evaluation of asphalt binders.