Permanent Deformation Resistance Research Articles

Mechanical performance of sustainable asphalt mixtures manufactured with copper slag and high percentages of reclaimed asphalt pavement

The use of reclaimed asphalt pavement (RAP) in the construction of hot mix asphalt (HMA) pavements is a widely used alternative in the development of sustainable road infrastructure. For this reason, the use of higher RAP contents continues to be a topic of interest. This study evaluated the performance of semi-dense asphalt mixtures incorporating 50% to 70% RAP and 7.5% and 15% copper slag (CS) as partial replacement of aggregate, to determine the influence of CS on the effective increase of RAP in the design of sustainable asphalt mixtures. The mixtures were evaluated using macrotexture, fatigue strengths, water sensitivity, and the Hamburg wheel tracking test. The results show that the use of RAP improves the permanent deformation resistance (RD) and fatigue life of the mixtures, while the mean texture depth (MTD) and indirect tensile strength ratio (ITSR) decrease. The incorporation of CS in the mixtures with RAP improved MTD and ITSR compared to the mixtures including only RAP and allowed higher RAP contents in fatigue and Hamburg wheel tests without showing a negative influence.

Empirical correlation of the modified wheel tracker (MWT) and the dynamic creep test for evaluating the permanent deformation of hot mix asphalt (HMA)

The wheel tracking test (WTT) has been extensively used for laboratory characterization of permanent deformation of hot mix asphalt (HMA). However, the fully-confined setup of the device is unable to capture the tertiary zone where shear deformation takes place. This makes the permanent deformation resistance characteristics of HMA difficult to analyze. Hence, a modified wheel tracker (MWT), with unconfined lateral sides along the wheel tracking direction was utilized in this study, which can capture the tertiary flow (referred to as the flow number (FN)). The dynamic creep test, which yields FN, is a common laboratory test which has the ability to characterize permanent deformation considering the shear behavior. The study investigated the relationship of the MWT and the dynamic creep test utilizing the permanent deformation and permanent microstrain data from the respective tests. A novel parameter, FN-Index was explored. The permanent deformation parameters derived from the MWT were well correlated with the dynamic creep test. The MWT showed promising repeatability for the FNs.

Study of High-Temperature Properties of Asphalt Mixtures Used for Bridge Pavement with Concrete Deck.

The paper presents the issue of resistance to permanent deformations of bridge pavements placed upon concrete bridge decks. In Europe, bridge asphalt pavement usually consists of a wearing course and a protective layer, which are placed over the insulation (waterproofing). Protective layers of bridge pavement are commonly constructed using low air void content asphalt mixes as this provides the suitable tightness of such layers. Due to increased binder content, asphalt mixes for bridge pavement may have reduced resistance to permanent deformations. The article presents test results of resistance to permanent deformations of asphalt mixes for the protective layers. In order to determine the composition of mixtures with low air void content and resistance to permanent deformation, an experimental design was applied using a new concept of asphalt mix composition. Twenty-seven different asphalt mixture compositions were analyzed. The mixtures varied in terms of binder content, sand content and grit ratio. Resistance to permanent deformation was tested using the laboratory uniaxial cyclic compression method (dynamic load creep). On the basis of experimental results and statistical analysis, the functions of asphalt mixture permanent deformation resistance were established. This enabled a determination of suitable mixture compositions for protective layers for concrete bridge decks.

Effect of addition of pigments on thermal characteristics and the resulting performance enhancement of asphalt

Lower thermal conduction and higher specific heat of conventional black pavement result in extreme surface temperatures during summers. Asphalt being highly temperature-dependent and viscoelastic, is more vulnerable to damage under vehicular loading at these temperatures. It also contributes towards Urban Heat Island (UHI) effect, hence demanding for non-black pavement surfaces by use of coloring additives which could help in the surface temperature reduction. Iron oxide red and Titanium dioxide white pigments are used to decolor the black mixes. Asphalt and bitumen samples were thermally investigated in heat sinks at three different solar fluxes. Pigment dosage was kept at 4% by weight of total mix for all the types of pigments. Samples were heated and cooled for 3 and 2 h, respectively. The effect of change in temperature of pigmented samples was also verified through performance testing. Cooper wheel tracking and dynamic modulus tests were performed to assess the high-temperature performance while fatigue parameters were assessed with a four-point bending beam fatigue test. Rheology of binder was assessed using Dynamic Shear Rheometer (DSR). Moreover, Rolling Bottle Test and Bitumen Bond Strength Test were also performed to check moisture sensitivity. Results showed that pigmented binder remain 8–10 ⁰C cooler while pigmented asphalt mixtures remain 4–5 ⁰C cooler as compared to unmodified samples. Performance tests reflected higher permanent deformation resistance at higher temperatures without compromising the fatigue property at lower temperatures. Rheology also depicted an increase in stiffness of pigmented binder, indicating better performance at higher temperatures. Use of pigments also enhances the moisture resistance/adhesion of the binder.

Evaluation of Properties and Micro-Characteristics of Waste Polyurethane/Styrene-Butadiene-Styrene Composite Modified Asphalt.

In order to solve the problems caused by asphalt diseases and prolong the life cycle of asphalt pavement, many studies on the properties of modified asphalt have been conducted, especially polyurethane (PU) modified asphalt. This study is to replace part of the styrene-butadiene-styrene (SBS) modifier with waste polyurethane (WP), for preparing WP/SBS composite modified asphalt, as well as exploring its properties and microstructure. On this basis, this paper studied the basic performance of WP/SBS composite modified asphalt with a conventional performance test, to analyze the high- and low-temperature rheological properties, permanent deformation resistance and storage stability of WP/SBS composite modified asphalt by dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. The microstructure of WP/SBS composite modified asphalt was also observed by fluorescence microscope (FM) and Fourier transform infrared spectroscopy (FTIR), as well as the reaction between WP and asphalt. According to the results of this study, WP can replace SBS as a modifier to prepare WP/SBS composite modified asphalt with good low-temperature resistance, whose high-temperature performance will be lower than that of SBS modified asphalt. After comprehensive consideration, 4% SBS content and 15% WPU content (4 S/15 W) are determined as the suitable types of WPU/SBS composite modified asphalt.

Fabrication of urea formaldehyde–epoxy resin microcapsules for the preparation of high self‐healing ability containing SBS modified asphalt

AbstractAsphalt exhibits self‐healing ability, though at a lower rate. In this study, urea formaldehyde–epoxy resin (UFE) microcapsules were prepared using polyurea formaldehyde as the wall and epoxy resin as the core material, which were in turn applied to fabricate UFE–styrene butadiene styrene modified asphalt (abbreviated as UBS asphalt). Scanning electron microscopy and transmission electron microscopy analyses revealed well‐coated microcapsules have globular geometry with obvious folds in the wall. Ductility test showed 90% higher healing rate of UBS asphalt than pure styrene butadiene styrene (SBS) modified asphalt. Dynamic shear rheometer and multi‐stress creep recovery tests indicated that UFE microcapsule incorporation can improve the viscoelasticity, high temperature stability, and permanent deformation resistance of pure SBS modified asphalt attributed to the even distribution of UFE microcapsules in asphalt and their better mutual compatibility, which was confirmed by fluorescence microscopy. At 100 and 3200 Pa, the recovery rate of 0.4% UBS asphalt was 32.1% and 71.7% higher than that of the original SBS modified asphalt, respectively. UFE microcapsule and asphalt only physically interacted as confirmed by Fourier infrared spectroscopy analysis. This study provides a feasible alternative approach for the preparation of UBS asphalt with enhanced mechanical properties and thermal stability for applications in construction and highway industries.

A new approach to laboratory roller compaction method and its influence on surface texture and permanent deformation of asphalt mixtures

ABSTRACT Pavement structures must guarantee safety, trafficability and comfort to highways users during its service life. The quality of these parameters is related to distresses that may occur as surface distortions, that might be caused by mechanical behaviour problems and to surface texture, which also affect highway safety. The surface texture is evaluated by parameters such as microtexture and macrotexture, related to aggregate rugosity and mixture characteristics, respectively. Both mechanical behaviour and surface texture can be affected by the compaction method of the mixture, as it affects the internal structure and the internal friction between aggregate particles, resulting in alterations in the permanent deformation resistance and surface aspects of the mixture. Hence, this paper proposed a new laboratory compaction method, using roller compaction with vibration, considering three aggregate gradations. This study evaluated the effect of the laboratory compaction method in the permanent deformation resistance and the surface texture of samples, comparing to field mixtures. The proposed compaction method presented efficiency for dense-graded mixture. The mixture's performance regarding mechanical behaviour and surface texture according to the compaction method variation was also dependent on the aggregate gradation. Mixtures with a discontinuity on the gradation presented a negative impact due to the vibration process.

Effects of bamboo fiber on the mechanical properties of asphalt mixtures

Fiber addition could enhance the permanent deformation and crack resistance of the asphalt mixture. Previous research has found the effect of fibers on asphalt mixtures, while bamboo fibers have been overlooked. Bamboo fibers involve strength and toughness properties, and the addition of bamboo fibers is significant for studying the improvement of the mechanical performance in asphalt mixtures. In this paper, the reinforcing effects of bamboo fiber on the mechanical properties of asphalt binders and mixtures are investigated under various loading and temperature conditions. Bending beam rheometer tests and frequency sweep tests using dynamic shear rheometer were conducted in this study to characterize the relevant properties of asphalt binder with different fiber contents. A Superpave gyratory compactor was used to produce asphalt mixture specimens with 0.3% bamboo fiber. In addition, dynamic modulus, stress sweep rutting, and cyclic fatigue tests were conducted to investigate the mechanical properties of the test specimens. The results indicate that the high-temperature shear strength and low-temperature flexibility of the asphalt binders were improved by the inclusion of bamboo fiber. The inclusion of only 0.3% bamboo fiber improved the rutting resistance and fatigue life of the asphalt mixtures. In general, the dynamic modulus values of the asphalt mixtures increased and the phase angles decreased with the addition of bamboo fiber. The performance test results show that the inclusion of bamboo fiber enhances the stiffness and cracking performance of asphalt mixture at the intermediate temperature, but the improvements are not significant at high temperature. The research could evaluate the mechanical properties of bamboo fiber asphalt mixtures, and provide a reference for the engineering application of bamboo fiber in asphalt mixtures.

Performance Evaluation of WMA Containing Re-Refined Acidic Sludge and Amorphous Poly Alpha Olefin (APAO)

The use of waste materials has been increasingly conceived as a sustainable alternative to conventional materials in the road construction industry, as concerns have arisen from the uncontrolled exploitation of natural resources in recent years. Re-refined acidic sludge (RAS) obtained from a waste material—acidic sludge—is an alternative source for bitumen. This study’s primary purpose is to evaluate the resistance of warm mix asphalt (WMA) mixtures containing RAS and a polymeric additive against moisture damage and rutting. The modified bitumen studied in this research is a mixture of virgin bitumen 60/70, RAS (10, 20, and 30%), and amorphous poly alpha olefin (APAO) polymer. To this end, Marshall test, moisture susceptibility tests (i.e., tensile strength ratio (TSR), residual Marshall, and Texas boiling water), resilient modulus, and rutting assessment tests (i.e., dynamic creep, Marshall quotient, and Kim) were carried out. The results showed superior values for modified mixtures compared to the control mix considering the Marshall test. Moreover, the probability of a reduction in mixes’ moisture damage was proved by moisture sensitivity tests. The results showed that modified mixtures could improve asphalt mixtures’ permanent deformation resistance and its resilience modulus. Asphalt mixtures containing 20% RAS (substitute for bitumen) showed a better performance in all the experiments among the samples tested.

Studying the mechanical properties of improved cold emulsified asphalt mixtures containing cement and lime

Cold emulsified asphalt mixtures (CEAM) is a cost-effective and ecological technique for bituminous road pavements construction. This investigation evaluates the mechanical properties and durability of CEAM modified using cement and lime as filler replacement. The initial and long-term stiffness modulus, water damage resistance, permanent deformation and fatigue cracking resistance were investigated. To achieve this objective, different laboratory tests were carried out, including stiffness modulus, water damage resistance, wheel tracking and fatigue tests. The results show that incorporating cement and lime in cold emulsified mixtures have an optimistic impact on the mechanical properties and performance. In addition, accelerate the curing time was achieved using such modifiers that are capable of absorbing water.

Effect of Aggregate Gradation and Morphology on Porous Asphalt Mixture Performance

Previous studies have reported the effects of aggregate gradation and angularity on the pavement performance of hot asphalt mixtures, while little work has been done on the role of aggregate gradation and morphology related to porous asphalt (PA) mixture performance. The primary objective of this article was to evaluate the effects of aggregate gradation and morphology on the mechanical properties and volumetric characteristics of PA mixtures. Ten PA mixtures, prepared by regulating the percentages of aggregate passing 9.5-, 4.75-, 2.36-, and 1.18-mm sieves and using two types of aggregate sources, were compared by evaluating air voids, shear strength, Marshall stability, indirect tensile strength, and micromorphology. The analytic hierarchy process method was used to analyze the priority weights of various influencing factors on PA mixture performance. The results indicate that aggregate gradation had significant effects on the performance of the PA mixtures. There was an excellent linear relationship between the percentages of aggregate passing the 9.5-, 4.75-, and 2.36-mm sieves and the respective mixture air voids. Increasing the proportion of 4.75–9.5-mm aggregate particles in the PA mixes did not contribute to its moisture damage resistance. The percentage of 2.36–4.75-mm aggregate fractions was the most critical influencing factor for the PA mixtures’ mechanical properties and volumetric characteristics. Additionally, aggregate morphology does affect PA performance. The permanent deformation resistance and moisture resistance were notably improved as the aggregate sphericity value increased. Based on the test results, the mechanical properties and volumetric characteristics of PA mixtures can be optimized depending on engineering requirements by regulating the aggregate gradation and type.

Performance Assessment of Asphalt Mixture Produced with a Bio-Based Binder.

Nowadays, the growing energy costs and pressing worldwide demand for petroleum-based products create a strong need to develop alternative binders deriving from green and renewable sources. Bio-binders (or bitumen added to bio-based materials) can potentially be a viable alternative for the production of bituminous mixture, promoting the circular economy as well as environmental sustainability principles without reducing the overall performance of the mixture. In this context, the current study focuses on evaluation of the effects of a bio-binder on the mechanical response of asphalt concrete (AC) produced with it. In particular, a 10% bio-oil deriving from a by-product of the paper industry has been blended with a conventional 50/70 penetration grade bitumen to obtain the bio-binder. Moreover, plain bitumen having the same consistency was chosen to produce a reference AC. Two dense-graded AC wearing courses were prepared in the laboratory according to Italian technical specifications. A mechanical characterization in terms of indirect tensile strength, indirect tensile stiffness modulus, fatigue response and permanent deformation resistance was performed on gyratory compacted specimens using both conventional and performance tests. In addition, aging and water sensitivity of the AC specimens were evaluated. Overall results highlight that the AC produced with the bio-binder did not show reduced mechanical properties and it was comparable to the reference AC regardless of aging and water conditioning. This highly encourages the use of bio-binder as a viable alternative in asphalt technology.

Permanent Deformation and Rutting Resistance of Demolition Waste Triple Blends in Unbound Pavement Applications.

Virgin quarried materials are becoming increasingly scarce in our environment, and these materials are no longer a viable or economical solution for the construction industry. The construction industry is constantly seeking new markets for recycled waste in civil engineering applications. This research’s primary focus is the optimization of the usage of recycled materials such as recycled glass (RG), crushed brick (CB), and crushed concrete (CC), in pavement base/sub-base applications. Various percentages of RG, up to 40%, were blended with two types of CC in this research. The CC and CB, which were used as triple blends in this research, were utilized for the upper (100% CC) and lower sub-bases (up to 50% CB). This study sought to establish the maximum amount of RG that could be incorporated in the triple blends with CB and CC whilst maintaining an acceptable performance. Thus, a comprehensive series of fundamental and advanced geotechnical laboratory tests, including repeated load triaxial (RLT) and wheel-tracker (WT) tests, were performed to assess the engineering properties and permanent deformation characteristics of these triple blends. The particle-size distribution curve and California Bearing Ratio (CBR) values of all the blends met the minimum requirements. Results of RLT tests confirmed that all the nominated blends were found to provide the resilient modulus value required to be used as pavement materials. The WT results on the triple blend with 15% RG showed that the specimen performed exceptionally well during the test and comfortably met the requirements to be used in pavement applications. Based on the engineering properties and permanent deformation results, up to 15% RG can be suggested for incorporation as an accompanying material in unbound roadwork applications. Subject to the outcomes of future field testing, there might be potential to increase the percentage of RG added in the blends up to 30%.

Investigation of the performance properties of asphalt binders and mixtures modified by Crumb Rubber and Gilsonite

The mechanical performance properties of asphalt binders and mixtures can be enhanced by utilizing several modifiers, including Crumb Rubber (CR) and gilsonite. The current study evaluated the effects of CR and gilsonite additive on the rheological behavior of gilsonite and CR/gilsonite composite modified binders and Stone Matrix Asphalt (SMA) mixtures. In this research, to modify original binder, gilsonite (0%, 10%, 20%, 30% and 40% by weight of binder), and CR (5%, 10%, 15%, and 20% by weight of binder) were used. The modified binders were subjected to rotational viscosity (RV), dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), and linear amplitude sweep (LAS) tests. Also, the gilsonite and CR/gilsonite modified mixtures were subjected to four-point beam fatigue (FPBF), resilient modulus (Mr), indirect tensile strength (ITS), dynamic creep, and wheel track tests. The results revealed that the utilization of gilsonite reduced the low temperature cracking resistance of binders while adding CR to gilsonite modified binders, the low-temperature cracking of modified binders enhances. According to the results, utilization of gilsonite causes a decrease in the resistance of binders against fatigue cracking, while adding CR to gilsonite modified binders, the fatigue life of binders increases. Results revealed that both gilsonite and CR enhance the elasticity and recovery properties of binders, and consequently, the strength of binders versus permanent deformation improves. Mixture test results revealed that using gilsonite and CR increases the Mr, permanent deformation resistance, tensile strength, fracture energy, and intermediate temperature performance of specimens. It can be concluded from the results that CR has a positive impact on enhancing the gilsonite modified binders and mixtures performance.

Nano-Silica modifier asphalt concrete under rutting resistance and shape memory component

Permanent deformation is pavement distress that has been the root cause of failure of roads globally. With the formation of a rut, follows cracking which inevitably damages the asphalt and sub-base layers. To curb the rutting distress, this study investigates the use of nanosilica, miniaturized silica particles to the power of 10-9 to modify the binder of the asphalt concrete. The nano-silica was added at 4%, 6% and 15% by weight of bitumen into the asphalt mixture. Marshall Mix design method was used to prepare the forty-eight samples used in the study. Repeated Load Permanent Deformation (RLPD) test and Shape Memory (SM) were performed at two temperatures (25°C and 40°C). It was found that the rutting resistance and shape memory had the best performance with the addition of 15% nano-silica at 40°C. Addition of nano-silica at 15% by weight of bitumen had the best amelioration of not only permanent deformation resistance but also shape retention thus enhancing pavement performance.

Stress and Strain Characteristic of Stone Mastic Asphalt Incorporating Eggshell Powder

Stone mastic asphalt (SMA) is a type of gap graded asphalt mixture. Due to large difference between the gap of large and small size aggregate, this type of mixture suffers a few drawbacks such as low resistance towards permanent deformation. Thus, the usage of ecofriendly and sustainable additive is crucial in enhancing the performance of SMA. Thus, this study is utilizing various amount of eggshell powder as asphalt modifier. Among the tests involve to evaluate the stress-strain characteristic of modified SMA are Resilient Modulus Test and Dynamic Creep Test. From the test, it shows that the addition of 4% eggshell powder produces the highest value of resilient modulus and lowest value of dynamic creep for SMA. In conclusion, this study proves that the eggshell powder is capable in enhancing the performance of SMA especially in terms of permanent deformation resistance.

Machine Learning Approach to Develop a Novel Multi-Objective Optimization Method for Pavement Material Proportion

Asphalt mixture proportion design is one of the most important steps in asphalt pavement design and application. This study proposes a novel multi-objective particle swarm optimization (MOPSO) algorithm employing the Gaussian process regression (GPR)-based machine learning (ML) method for multi-variable, multi-level optimization problems with multiple constraints. First, the GPR-based ML method is proposed to model the objective and constraint functions without the explicit relationships between variables and objectives. In the optimization step, the metaheuristic algorithm based on adaptive weight multi-objective particle swarm optimization (AWMOPSO) is used to achieve the global optimal solution, which is very efficient for the objectives and constraints without mathematical relationships. The results showed that the optimal GPR model could describe the relationship between variables and objectives well in terms of root-mean-square error (RMSE) and R2. After the optimization by the proposed GPR-AWMOPSO algorithm, the comprehensive pavement performances were enhanced in terms of the permanent deformation resistance at high temperature, crack resistance at low temperature as well as moisture stability. Therefore, the proposed GPR-AWMOPSO algorithm is the best option and efficient for maximizing the performances of composite modified asphalt mixture. The GPR-AWMOPSO algorithm has advantages of less computational time and fewer samples, higher accuracy, etc. over traditional laboratory-based experimental methods, which can serve as guidance for the proportion optimization design of asphalt pavement.

Evaluation of Susceptibility of Asphalt Binders to Rutting through MSCR Test

Using modified asphalt binder is one of the most effective methods to solve the rutting problem of asphalt pavement, but the traditional G∗/sin δ parameter is not enough to characterize the rutting resistance of modified asphalt in field use. In order to accurately evaluate the high temperature performance of asphalt and establish the relationship between the rutting resistance of binder and mixture, two kinds of matrix asphalt and three kinds of modified asphalt were selected for DSR and MSCR tests. G∗/sin δ, nonrecoverable creep compliance Jnr, recovery rate R, and other parameters were used to characterize the permanent deformation resistance of the binder, and the correlation between these parameters and the results of rutting test was analyzed. The results show that Jnr3.2 can accurately characterize the permanent deformation resistance of asphalt, while the stress sensitivity index Jnrdiff is not applicable to all types of modified asphalt. In contrast, Jnrslope can better reflect the stress sensitivity of asphalt, and Jnrslope is significantly correlated with the results of rutting test.

Laboratory evaluation of the effect of kapok fibers on the rheological and fatigue properties of bitumen

In this paper, kapok fiber (KF) was used as a bio-reinforcement material to modify virgin bitumen, and the rheological properties of the modified bitumen were studied. During the research, the fiber surface was treated utilizing silane coupling agent (KH-550), and the surface microstructure was characterized by scanning electron microscope (SEM). To observe the change of KF on the rheological properties of bitumen, rotational viscosity test, dynamic shear rheometer test, multiple stress creep recovery test, bending beam rheometer test and linear amplitude sweep test were carried out. The results indicated that KH-550 improved fiber surface roughness and strengthened the mutual bonding ability of fiber and asphalt. After adding KF, the viscosity and permanent deformation resistance of bitumen were improved. However, KF had a slight negative effect on the low temperature crack resistance and fatigue resistance in bituminous binder, the effect was relatively less on the premise of no more than 6% fiber content.

Effect of Diatomite and Basalt Fibers on Pavement Performance and Vibration Attenuation of Waste Tires Rubber-Modified Asphalt Mixtures

As an eco-friendly pavement material, waste tires rubber-modified asphalt mixtures (WRMs) have been applied in pavement engineering widely. To further improve the performance and adaptability of WRM, diatomite and basalt fibers are, respectively, added to WRM. Subsequently, the Marshall tests, the rutting tests, the low-temperature splitting tests, the freeze-thaw splitting tests, and the vibration attenuation tests are conducted to study the effect of diatomite and basalt fibers on pavement properties of WRM. Furthermore, the correlation degree between the content of diatomite, basalt fibers, asphalt, and the pavement properties of WRM is analysed by the grey correlation grade analysis (GCGA). The results show that the addition of diatomite and basalt fibers can significantly improve the pavement and vibration attenuation properties of WRM. The improvement of high-temperature permanent deformation resistance, low-temperature cracking resistance, and water damage resistance of WRM is mainly attributed to diatomite, basalt fibers, and asphalt-aggregate ratio, respectively. The improvement of the vibration attenuation of WRM by diatomite and basalt fibers is mainly attributed to the increase of waste tires rubber-modified asphalt (WRA) content caused by adding diatomite and basalt fibers.