Hot Mix Asphalt Pavements Research Articles

Evaluation of Limestone from Cretaceous to Tertiary age in Kurdistan Region of Iraq for Heavy Duty Road Pavement

Aggregates have an important role in the development and quality of Hot Mix Asphalt pavement, Engineers prefer using different types of acidic aggregates as a dominant road pavement mixture. This study is focused on using a basic aggregate, for this purpose limestone is used as a replacement to sandstone and gravel in the Hot Mix Asphalt for base and binder course, due to its rough, tough, durable and stable properties, that adheres well with the binder due to its hydrophobic properties. A petrographic study and chemical analysis by XRF method was carried out for better determining the mineralogical and chemical contents. Los Angeles Abrasion test carried out for measuring abrasion of the limestone aggregates in Kurdistan Region Iraq from Cretaceous-Tertiary age in different sources of the Shiranish Formation in Pirat, Harir, and Safin, Aqra-Bekhme in Shakrok, the Pila Spi Formation in Pirmam, Khurmala Formation in Safin, the Euphrates Formation in North Qarachugh, and the Qamchuqa Formation in Bana Bawi, while the only last four formations selected for Marshal test depending on wear <45% according to Iraqi SORB, 2003 standards. The soundness test results showed that the selected four samples are within the required specifications. The aggregate-asphalt mixture molds were prepared with the optimum binder content of 4.7%, for the Marshall stability test, which revealed that all the selected four samples are suitable as a heavy-duty pavestone for the base and binder course, with BQ and Pm showed optimum stability results.

Comparison of Bond Strength Evaluation Methods Between Pavement Layers

Tack coats are generally used to facilitate a bonding between pavement layers in construction of hot-mix asphalt pavements and overlays. The goal of applying a tack coat material is to ensure the new or consecutive pavement layers respond monolithically under loading and avoid premature failure caused by debonding, mat slippage, or fatigue cracking. Multiple different in-situ and laboratory tests have been developed to evaluate bond strength of tack coat materials under tension, shear, and mixed-mode loading mechanisms. However, there is no universally accepted bond strength test method or performance criteria for tack coats within the United States. While some specifying agencies have gained familiarity and comfort with a particular bond strength test, a gap exists for many states that have not adopted a testing procedure. The objective of this paper is to compare current and newly developed tack coat bond strength tests to help determine which is most indicative in predicting field performance. Field cores from four different pavement sections with varying traffic loading conditions and early bond strength performance were sampled and tested in the laboratory using four different bond strength evaluation methods. Statistical analysis of bond strength testing results shows a strong linear correlation between pull-off and shear strength testing. Meanwhile, a novel approach to tack coat bond testing under cyclic tensile loading was explored and showed appreciable discrimination between sample locations and agreement with early field performance.

Laboratory evaluation on performance of emulsified asphalt modified by reclaimed ion exchange resin

The cold recycling technology using emulsified asphalt (EA) as the binder reduces the high pollution and high energy consumption of hot mix asphalt (HMA) pavement. However, the poor bonding ability and high temperature deformation resistance of EA limit its application. To improve the performance of EA and reduce the pollution of waste ion resin to the environment, this study used reclaimed ion exchanged resin (RIER) to modify EA and analyzed its performance through laboratory tests. Firstly, the ionic characteristics and basic properties of reclaimed ionic resin-modified emulsified asphalt (RIEA) were tested. In addition, the rheological properties of evaporation residues of reclaimed ionic resin-modified emulsified asphalt (RIEA) were tested by Dynamic Shear Rheometer (DSR). The interaction effect of RIER and evaporation residue of EA were analyzed by PalierneC model. After that, the adhesive properties and tensile properties of RIEA mixtures were characterized by boiling test and splitting test. Finally, the microscopic physical and chemical properties of RIEA evaporation residue were tested by Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectrometer (FTIR). The results showed that RIER improved the stability of RIEA. The conductivity of EA increased by 294 % and the Zeta potential increased by 36 % when the RIER content was 30 %. Meanwhile, the penetration degree and ductility of RIEA evaporation residue were decreased, the softening point of that were increased. The Brookfield viscosity of EA with 30 % RIER content increased by 181 %, the dynamic viscosity increased, and the adhesion performance was improved. In addition, the complex shear modulus (G*) and rutting coefficient (G*/sinδ) of RIEA evaporation residue increased, while its phase angle (δ)decreased. The PalierneC interaction model exhibited that the interaction of EA and RIER showed different temperature responses with the change of loading frequency. The indirect tensile strength (ITS) of RIEA mixture was improved by adding RIER, and its value reaches the maximum value when the amount of RIER added is 30 %. RIER and EA are tightly bound in microstructure, and they interweave to form a glue-linked structure. FTIR results show that, the RIEA evaporation residue exhibited new absorption peaks at 1793.4 cm−1, 1302.1 cm−1, 876.0 cm−1, 806.1 cm−1 wavenumbers indicating a chemical reaction between them.

Uncovering the Hidden Value of Waste Cow Bones Towards their Use as a Sustainable Biofiller for Hot-Mix Asphalt Paving Applications

This work is aimed at uncovering the hidden value of waste cow bones towards their use as a sustainable biofiller for hot-mix asphalt (HMA) paving applications. To do so, the effect of various contents of calcined cow bone powder (e.g., 5, 10, and 15 wt. % CBP) on the AP-5 bitumen performance was investigated. Numerous lab techniques were adopted to assess the physicochemical attributes of finished filler-asphalt mastics, namely: elemental analysis, Fourier transform-infrared spectroscopy (FT-IR), thin-layer chromatography-flame ionization detection (TLC-FID), needle penetration, ring and ball softening point, Brookfield viscometer, and ductility. Iatroscan analysis revealed that the CBP treatment did not alter the saturates but induced an increase in the fractions of aromatics/asphaltenes and a decrease in the resins. The FT-IR scan highlighted that the CBP–binder interactions were mainly governed by physical mechanisms rather than chemical ones. The empirical methods showed that the CBP incorporation enhanced the stiffness/hardness, the consistency, as well as the high-temperature performance of bituminous mixtures. Overall, the use of waste cow bones as a green biofiller is viable and profitable, and it has the potential to reduce the environmental pollution caused by the livestock industry while also improving the performance of hot-asphalt mixes and extending the pavement life at a low cost.

Feasibility Evaluation of Waste Palm Oil Clinker Powder as a Fillers Substitute for Eco-Friendly Hot Mix Asphalt Pavement

Feasibility Evaluation of Waste Palm Oil Clinker Powder as a Fillers Substitute for Eco-Friendly Hot Mix Asphalt Pavement

Evaluating the cost of collection, processing, and application of face masks in hot-mix asphalt (HMA) pavements

Human activities significantly contribution to the yearly generated plastic wastes. Moreover, the enormous increase in face masks and face shields caused by the emergence of the COVID-19 pandemic has doubled the generated plastic wastes. Although there is an added benefit of using plastic waste in construction, the cost associated with their application, specifically the face mask, has not been addressed. This paper presents a simplified and rapid estimation of the cost associated with the collection, processing, and application of face masks in hot-mix asphalt (HMA) pavements. Two scenarios, mask modified asphalt pavement and conventional asphalt pavement, are considered. The total cost is based on market price and prices from waste management facilities and plastic processing companies. Life Cycle Cost Analysis (LCCA) is used to evaluate the long-term costs of mask modified asphalt pavement and conventional asphalt pavement. Results show that no significant difference in initial total cost between the two scenarios for pavement sections with lengths less than 500m and the number of lanes less than 6. The difference in total cost begins with lengths greater than 500 m for 5 and 6 Lanes. Despite the higher initial costs for the mask modified asphalt pavement, the LCCA shows that there is a 29% maintenance cost reduction over the 40 years life cycle of the asphalt pavement. The use of LCCA shows the benefit of the selection of the most cost-effective strategy and how the use of mask modified asphalt pavement over the conventional asphalt pavement can save money over the life cycle of the asphalt and improve rutting and stiffens.

Technical and economic feasibility study of roller-compacted concrete (RCC) and stone mastic asphalt (SMA) with hot-mix asphalt (HMA) pavement

Technical and economic feasibility study of roller-compacted concrete (RCC) and stone mastic asphalt (SMA) with hot-mix asphalt (HMA) pavement

Rheological, Aging, and Microstructural Properties of Polycarbonate and Polytetrafluoroethylene Modified Bitumen.

Deterioration of asphalt pavements due to massive load of vehicles and climatic variation has demanded the use of pavements construction material with an excellent resilience characteristic, resistance to permanent deformation, and most importantly, a much longer service lifespan. The main structural distresses in pavement construction are permanent deformation at high temperatures and fatigue cracking under repetitive traffic loadings. To comprehensively investigate the performance of bitumen penetration grade (PG) 70 against rutting, fatigue, and high temperature cracking in hot mix asphalt (HMA) pavements, polycarbonate (PC) and polytetrafluoroethylene (PTFE) were used. The investigation of the internal structure, rheological, and physical properties of base and modified bitumen (MB) mixes with different percentages of modifiers (0%, 2.5%, and 5%) by weight were performed via scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) analysis, X-ray diffraction (XRD) pattern analysis, rolling thin-film oven test (RTFOT), pressurized aging vessel (PAV), dynamic shear rheometer (DSR), rotational viscosity (RV), and bending beam rheometer (BBR). The results of the RV test indicate that modification of neat bitumen with polycarbonate and polytetrafluoroethylene increased the viscosity for polycarbonate-modified bitumen (PCMB), polytetrafluoroethylene-modified bitumen (PTFEMB), and for a blend of PCMB-PTFEMB by 44%, 50%, and 55.75% at 135 °C and 111.10%, 127.80%, and 138.88% at 165 °C, accordingly. BBR test results revealed that modifiers increased the rigidity of neat bitumen by 74.8%, 75.8%, and 74.5% at −16 °C, −22 °C, and −28 °C, respectively.

EQUIVALENT THICKNESS COEFFICIENT OF COLD CENTRAL PLANT RECYCLING PAVEMENT STRUCTURE

This research focuses on the equivalent relationship between cold central plant recycling mixture and hot mix asphalt. In this paper, the pavement surface condition index (PCI) was calculated by the road surface conditions investigating, which was used as the evaluation standard. The unreasonable data were removed by SPSS software. The existing decay equation of pavement performance was simplified by MATLAB, and optimized by the Marquardt and global optimization methods. The survey data were fitted nonlinearly by 1stOpt software. Ultimately, the multivariate nonlinear regression optimization equation of the equivalent thickness coefficient was established. The results show that the cold central plant recycling with the emulsified asphalt (CREA) pavement equivalent thickness coefficient is 0.587. The cold central plant recycling with the foamed asphalt (CRFA) pavement equivalent thickness coefficient is 0.632. In addition, the performance of 10 cm cold central plant recycling pavement is equivalent to 6 cm the traditional hot mix asphalt pavement. The dispersion of the CREA is greater than that of the CRFA significantly.

THE EFFECT OF STEEL SLAG POWDER ON HMA STABILITY

The goal of the study is to evaluate the improvements of the stability of the hot mix asphalt (HMA) after the addition of ground steel slag. Steel slag was grounded into finer 75µm particles at Bangladesh Road Research Laboratory (BRRL). Then the ground steel slag powder was added to asphalt binder for penetration and softening point tests. Three modified HMA mixes were prepared with 20%, 30% and 40% of steel slag powder and 2% of cement for the Marshall test with a control mix containing 2% of cement only. The Marshall stability result shows increased stability and decreased flow. Marshall stability reached to maximum at the level of 30% of steel slag powder. The flow values obtained showed a slightly decreasing pattern with the increase in steel slag. The density of the mixes slightly decreases with the increase of steel slag content in the asphalt binder. It was found that the ground steel slag has a negligible effect on air voids (Va), voids in mineral aggregate (VMA), and voids filled with asphalt (VFA). A designed mix was also achieved the best possible result for all parameters in this experiment setup. Ground steel slag can be used in HMA and asphalt pavement construction, which can result in reduced maintenance work and minimize the frequency of rehabilitation and contributes to economic and environmental development.

Long-Term Performance of Flexible Pavements Constructed on Recycled Base Layers

There has been an increased interest in using reclaimed asphalt pavement (RAP) aggregates as a base course in Wisconsin for the offered economic and environmental benefits. Laboratory studies showed that RAP can have resilient modulus values higher than typical natural aggregates, and can also have higher durability, especially in freeze–thaw cycles. However, it is also recognized that RAP exhibits temperature sensitivity and larger permanent deformations than natural aggregates. How these characteristics manifest themselves in the northern U.S. climates can only be assessed by long-term observation of field performance. Wisconsin Department of Transportation (WisDOT) has been using RAP as a base course for over 30 years. The qualitative assessment of WisDOT roads constructed with RAP showed they are performing adequately. However, this impression has not yet been verified quantitatively. This paper presents a quantitative assessment and comparisons for field performance of pavement test sections constructed with RAP and natural crushed aggregate (CA) base course layers in Wisconsin. The performance was evaluated using pavement distress surveys of roadways containing RAP and CA, falling weight deflectometer (FWD), dynamic cone penetrometer (DCP) tests, and analysis of WisDOT’s available data. Based on the field evaluation, the performance of the hot mix asphalt (HMA) pavements with RAP was found adequate and comparable to those with CA base course layers. A recommendation was given that WisDOT shall continue the practice of using RAP in base course layers of HMA pavements, given proper quality checks for materials, and proper quality control/quality assurance measures being applied during construction.

Sustainable paving alternative for low-volume roads using cold recycled asphalt

Reclaimed asphalt pavement (RAP) is a waste generated by removing asphalt material from a pavement. If RAP is not recycled, the pavement will require new asphalt layers, typically formed by virgin materials (bitumen and aggregates). One way to recycle RAP is by applying the cold-asphalt technique with bitumen emulsion as an additive, which potentially has environmental benefits. This technique can be a cost-effective alternative for low-volume road (LVR) networks that connect to main asphalt-paved roads. The objective of this research is to analyse the alternative of paving with RAP using cold bitumen emulsion as a binder. This pavement structure was compared with a traditional hot-mix asphalt pavement as an alternative for LVRs. The environmental impact analysis, through a streamlined life-cycle analysis, showed that the cold recycled alternative typically generates 50% less impact than a traditional pavement. In terms of global warming, the hot-mix asphalt pavement generates three times more emissions than the cold recycled alternative. The most important factors in these differences are the in situ construction technique of the RAP alternative and, as is the case in Chile, the long distances to a hot-mix asphalt plant.

Performance evaluation of cold in-place recycling materials through a simple semi-circular bending test

Cold in-place recycling (CIR) is a method of recycling existing Hot Mix Asphalt (HMA) pavements. In this study, a new performance-based test method, called Fracture Index Value for Energy (FIVE), is developed to capture the fracture energy of the CIR materials. Furthermore, various stabilisation agents were used including engineered emulsion (EE), high float asphalt emulsion (HFMS-2s), commodity asphalt emulsion (CSS-1) and foamed asphalt. The FIVE test was first validated using disk-shaped compact tension (DCT) test and then was implemented on the study mixtures at their optimum stabilisation agent contents. The ranking of the mixtures and reproducibility of the FIVE test was proved to be true through inter-lab comparisons of the test results between two independent testing laboratories. The statistical testing results postulate that the FIVE test is a simple test method that is capable of characterising the cracking performance of the CIR mixtures.

A model for variation with time of flexiblepavement temperature

Abstract The bituminous material performance is affected basically by the prevailing temperatures. The mechanical properties of these materials can vary significantly with the changes in the temperature magnitude. Hot mix asphalt (HMA) is a visco-elastoplastic material, so the pavement structural capacity is affected by the temperature variations. To determine the characteristics of the strength of the flexible pavement rationally, the prediction of the distribution of temperature in HMA pavement layers is a must. Heavy loadings subjected to highways and roads can cause serious deterioration to the HMA pavements. In this research, the temperature for three thicknesses of asphalt pavement structure was measured, and the air temperature to predict a model explains the relationship between the temperature and the depth of the pavement structure. The suggested model was successfully validated utilizing the data from three depths of asphalt pavement structure and the temperature on the surface of the asphalt pavement. The developed model consists of two independent variables, which are the depth within the pavement and ambient air temperature. The predicted model will be useful for the pavement designers those in need to predict the temperature of the profile of pavement to determine the engineering characteristics of field pavement.

Research of indoor molding of cold recycled foamed asphalt mixture with secondary hot compaction process considered

Cold recycled mixture using foamed asphalt (CRMF) has been widely used as a base due to its environmental advantages. The hot-mix asphalt (HMA) paved on top of the CRMF can produce a secondary hot compaction effect on the CRMF layer. However this secondary compaction effect cannot be considered in the current compaction methods in laboratory. This paper investigates the effect of secondary hot compaction on the CRMF base and optimized indoor molding of cold recycled foamed asphalt mixture with a secondary hot compaction process considered. Two types of indoor molding (secondary large Marshall compaction and secondary vibro-compaction) and two curing temperarues (40 °C and 60 °C) were employed in this study. The indirect tensile strength (ITS) and air voids are used to evaluate mixtures properties before and after the hot-mix asphalt paved for determining which indoor molding method is more consistent with the actual construction. The results indicate that the secondary hot compaction process is beneficial for increasing the ITS and moisture resistance, and decreasing the freezing-thaw resistance. The influence depth of the secondary hot compaction is limited, which is about 5 cm. The traditional one-time large Marshall compaction can only simulate conditions before HMA paving. The secondary large Marshall compaction matches well with the cases in the field. The compaction and curing conditions (compaction-130 blows per side + 48 h curing at 60 °C + compaction-20 blows per side + 24 h curing at room temperature) are recommended to fabricate CRMF in the laboratory.

A Laboratory evaluation of RAP modified mixtures for moisture susceptibility

Preparation of Hot mix asphalt (HMA) pavement construction of pavement layers involves in release of harmful gases which affects the environment conditions. The use of natural aggregates for the preparation of HMA is also affecting the natural resources. WMA is one among the technologies for reduction in mixing and compaction temperature RAP has the advantages for the use in partial replacement with natural aggregates in preparation of modified bituminous mix. In this study, it was investigated on usage of polypropylene fibres of 6mm length in Warm mix asphalt with recycled aggregates. For modification of base binder, Sasobit wax compound was added so as to improve the reduce the overall energy consumption and reduction in toxic emission during construction of pavement. The specimens were prepared under analytical gradation method. The main objective of this paper is incorporate the principle of sustainability in pavement construction by the usage of RAP with the inclusion of fibre at four different percentages with an interval 0.1 to know the performance of RAP modified mixtures. In this study, physical properties as well as ageing properties were performed on virgin, modified and RAP binder, specimens were produced for Marshall, Indirect tensile strength (IDT) to determine the moisture susceptibility and volumetric properties. The modified rap mix of 3% WMA of 15% RAP with 0.2% PP fibre and 0.3% rejuvenator, the above mix combination values obtained results has displayed better performance evaluation for moisture resistance with the inclusion of fibre in modified RAP mixes. This study shall provide direction for achieving environmentally friendly pavement technologies.

Use of COVID-19 single-use face masks to improve the rutting resistance of asphalt pavement

Today, the world faces an enormous increase in plastic waste pollution caused by the emergence of the COVID-19 pandemic. Plastic pollution has been already one of the greatest threats to our planet before the Coronavirus outbreak. The disposal of millions of personal protective equipment (PPE) in the form of face masks has significantly contributed to the generation of plastic waste and has exacerbated plastic pollution. In an attempt to mitigate pollution caused by the excess PPE waste, an innovative way was developed in this research to reduce pandemic-generated wastes by using the shredded face mask (SFM) fibers as an additive to hot mix asphalt (HMA) to enhance rutting resistance. Rutting or permanent deformation is one of the major distresses of asphalt pavement. Since the SFM behaves as a semi-liquid between 115.5 and 160 °C, which is in the range of HMA mixing and paving temperature, it can function as a binding agent to glue the aggregates. When the pavement is cooled down to ambient temperature, the hardened SFM can provide stability and stiffness to HMA. Based on the results of this study, the modified mixes exhibited excellent resistance to permanent deformation under the Asphalt Pavement Analyzer (APA), as rutting depth values were reduced from 3.0 mm to 0.93 mm by increasing the SFM content from 0% to 1.5%. From the rutting test results and premature distress mechanism study, the appropriate addition of SFM modifiers could improve the high-temperature properties of HMA that can be used to strengthen high-compression and shearing zones in the pavement structure.

Sustainability Evaluation of Cold In-Place Recycling and Hot Mix Asphalt Pavements: A Case of Qassim, Saudi Arabia

The construction of conventional hot mix asphalt (HMA) pavements results in a number of economic and environmental issues, such as the cost of new overlays and associated impacts on natural resources. Although the cold recycling with an emulsified asphalt-recycling agent holds certain benefits over the HMA, its implementation on different road types, ranging from farm-to-market roads to expressways, is yet contentious due to the need for sophisticated equipment and trained workforce. The present research developed a methodology to evaluate all the three dimensions of sustainability, including economic (construction cost), environmental (natural resource depletion), and social (need for advanced equipment and skilled labor) of various scenarios of RAP and conventional asphalt pavements. The present study evaluated an equivalent thickness of the Cold In-place Recycling (CIR) pavement, which behaves similar to HMA pavement under the influence of different traffic loads. Fifty CIR and HMA scenarios for different traffic volumes and pavement layers thicknesses were developed. Finally, the sustainability of all the scenarios was evaluated for traffic designation in Saudi Arabia using fuzzy-based multicriteria analysis. Ranking of scenarios found CIR as a more sustainable overlay option for the feeders, collectors, main urban streets, expressways, and heavily trafficked highways in industrial areas where ESALs (Equivalent Single Axle Loads) range between 2,000,000 and >31,000,000. Considering the limited availability of advanced equipment and skilled labor for CIR pavements, HMA was found be a more sustainable option for farm-to-market roads with the “very light” traffic class. The methodology will help the pavement managers in decision making regarding the selection of sustainable pavement technologies for different road types in Saudi Arabia and the rest of the world.

Determining the Void Ratio in Hot-Mix Asphalt Pavements Using Different Methods According to EN 12697

Inaccurate air void ratio based on erroneous bulk density can seriously affect the performance of the roadway and its quality. Therefore, several methods were improved to measure bulk density by using different techniques in the developed countries, while the Saturated Surface Dry (SSD) traditional method has been used in Gaza strip till present days. This study aims at providing a better understanding of the effect of the selected bulk density measurement method on the percentage of voids using four methods namely; Dimensional Method, Dry Method, Surface-Saturated Dry Method, and Paraffin Sealing Method. At Laboratory, sixty-nine specimens were prepared, thirty-three of them were prepared in the Marshal Design System in order to determine the optimum bitumen content of the three different mix types, and thirty-six of the specimens were taken from mixtures design in order to determine bulk density. Laboratory results showed that the SSD method is the best choice for measuring bulk density in dense and mastic mixtures. In addition, there are no differences between SSD and dry methods in mastic mix. The experimental study shows that the dimensional method is the only method suitable for the determination of bulk density (Gmb) in porous mix despite it always gives underestimated results for Gmb in all asphalt mixes. As a result, the dimensional method can be used as an indicator for the upper limit of voids, while the dry method can be used as an indicator to the lowest limit, regardless the type of mix. The study recommended to use new techniques to determine Gmb in open graded mixtures with more accurate methods rather than traditional ones.

Improving flexible pavement performance through suitable aggregate gradation

The objective of this study was to improve the performance of flexible pavement through suitable aggregate gradation. Thus, initially, the dynamic modulus of asphalt mixtures |E*| for different aggregate gradations were predicted, and suitable aggregate gradation was determined. Then the performance of three different pavement structures for two aggregate gradations (Mid and Suitable), using AASHTOWare Pavement ME Design 2.5. 5, were evaluated for local conditions of Izmir, Turkey. The analysis result revealed that using suitable values compared to middle values increased the |E*| and improved the rutting and fatigue resistance of all pavement structures for any traffic levels. The output of this study can be used as a guide for hot mixed asphalt mix design and pavement design based on Mechanistic-Empirical Pavement Design Guide as well.