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Go to Editorial ManagerFlexible and rigid pavements are commonly built for airport pavements to support the moving loads of aircraft during the pavement design life. Airport pavements represent a cornerstone of the aviation world. Their condition profoundly impacts safety, operational efficiency, airport capacity, and financial well-being. These meticulously engineered surfaces must withstand the immense stresses generated by aircraft during takeoff, landing, and taxiing. At the planning stage, the pavement structure, materials, aircraft loads, environmental conditions, and pavement damage models should be evaluated. Comparing with road pavement design, airport pavement structural design is unique in terms of the traffic loads supported by pavements with high load magnitude, significant tire pressure, and dynamic traffic conditions. Over time, deterioration stemming from environmental exposure, aircraft loading, and other factors becomes inevitable. This study aims to explore the various factors influencing airport pavement performance, review the existing methodologies for pavement design and maintenance, and propose enhancements to current practices to ensure long-term durability and safety of airport pavements. This study aims to explore the various factors influencing airport pavement performance, review the existing methodologies for pavement design and maintenance, and propose enhancements to current practices to ensure long-term durability and safety of airport pavements.
Reclaimed (recycled) asphalt pavement (RAP), the most recycled material worldwide, is the mostly reclaimed material utilized in hot mix asphalt. Polymer (Crumb rubber) incorporation frequently leads to enhanced durability and resistance to heat cracking and rutting, two forms of permanent deformation. It also relieves stiffness and minimizes fatigue damage. This study aims to gather all previous RAP-related research and crumb rubber CR, so that the impact of using these materials on mechanical, physical properties of asphalt pavement, environmental effect and cost effective are clarify and explained. The finding of this research proved that the use of RAP and CR provide considerable structural and financial enhancements to the construction.
Real-life strategies are applied to assess pavement functionality, high-quality performance, and durability throughout its service life. Estimating pavement maintenance and sustainability is difficult. High-performance continuous reinforced concrete pavement (CRCP) structural design and Jordanian natural zeolite (JNZ) as a sustainable supplementary cementitious material (SCM) and unique mixed cement for green manufacturing are researched in this paper. The results obtained from this study showed that replacing cement with JNZ powder at 0%, 10%, 15%, and 20% improved concrete performance. Natural zeolite-mixed cement preserved concrete quality and reduced the need for ordinary Portland cement (OPC) and sulfate-resistant cement (SRC) clinker. After that, slab universal testing equipment and Jordanian zeolite-blended cement-reinforced concrete slabs were developed for CRCP performance. Therefore, fresh concrete was tested for partial cement substitution and standard mixture workability. Compressive, tensile, and flexural strength tests on 7 and 28 days and durability test (water absorption) were utilized to assess concrete strength and natural zeolite's potential to reduce resource consumption and carbon footprint while maintaining structural integrity using Open LCA. Sustainable CRCP structure development improved performance, resource conservation, and carbon footprint over the prior mix, according to EIA (Environmental Impact Assessment) software and chemical tests. This research improves materials and supports global sustainability goals.
Rigid pavement slabs are erected on a prepared subgrade or foundation layer, providing a hard and continuous surface. Transverse joints made of dowel bars connect them, and longitudinal joints made of tie bars join them longitudinally. This study is an investigation of the impact of soil strength and concrete parameters on the effectiveness of dowel bars in rigid pavements. Moreover, three parameters were examined; California Bearing Ratio (CBR), concrete compressive strength and slab thickness. The analysis was conducted using the Ever FE program and focused on several axle configurations applied to the joint. The results indicate inverse association between the pavement slab thickness and the concrete strength, under the assumption of consistent soil strength. Moreover, an assortment of reduced shear forces on the dowel bars is seen when the soil strength values increase. It indicates that soil strength has a greater impact on the shear load of dowel bars compared to the qualities of concrete. Additionally, the type of axles used and the magnitude of soil strength were shown to have a significant effect on the shear load.
The main objective of this study is to design the asphalt pavement structure for the Alkut-Mayssan highway in Iraq as a case study by using PCASE application to determine the necessary thickness of CR-modified asphaltic layers. Additionally, Marshall tests were used to investigate the effect of the dry process crumb rubber modifier on the thickness of the binder coarse layer based on various variables, such as the crumb rubber modifier with different content (1, 2, 3, 4, 5)% and sizes (0.3mm, 2.36mm , 4.75mm, and mix gradation). The test results show that while pavement thickness reduced as crumb rubber gradation increases, MR values increase. Additionally, as compared to the control mixture, the addition of 1% of CR in various gradations could decrease the thickness of the asphalt binder layer.
Reflective cracking is a serious issue that Adversely influences the performance and longevity of asphalt overlays over deteriorated pavements. This review Looks for the Technologies which used to reduce the reflection cracks propagation by insert a new Strategies and different design materials. This research dealt with many treatments such as: increasing the layer thickness of Hot Mix Asphalt (HMA), creating modified asphalt by adding polymers to asphalt, rubberizing asphalt, carbon black, sulfur and other different materials. Geosynthetic materials were studied and analyzed to evaluate their ability to increase the layer tensile strength and minimize the effect of reflection cracks such as geotextiles, geogrids, and Stress Absorbing Membrane Interlayers (SAMI). The research shows that the increasing of overlay asphalt layer thickness leads to durability development. On the other hand, using developed materials like Polymer-Modified Asphalt and Stress Absorbing Membrane Interlayers (SAMI) Strategies leads to increasing the service life of the repaired pavement. The conclusion indicated that the development of overlay asphalt layer thickness and layer reinforcement and applying advanced environmental systems can be improving the pavement performance. These Strategies can produce a perfect solution to prevent or reduce the reflection cracks in rigid and flexible pavement.
The present research aims to develop a sustainable, high-performance grout mix for semi-flexible pavement applications by partially replacing Ordinary Portland Cement (OPC) with Metakaolin (MK) and Ground Granulated Blast Furnace Slag (GGBS). The experiments were carried out in two steps: Portland cement was partially replaced with MK (10%, 20%, and 30%) to determine the optimum mix proportions for rheological and mechanical behavior. The selected optimal MK content was mixed with GGBS at 50%, 60%, and 70% replacement levels. Flowability was evaluated using flow time tests, and DIOs assessed mechanical performance through compressive, tensile, and flexural strength testing. The results showed that a 20% MK replacement level achieved a balance between workability and strength, with an optimum flow time of 14.03 s and a compressive strength of approximately 32.2 kN at 7 days of age. However, incorporating GGBS with a 20% MK blend enhanced the sustainability of these blended grouts without sacrificing their mechanical properties. The MK-GGBS grout-60% GGBS (60% GGBS) showed the highest compressive and flexural strengths, which can be considered for semi-flexible pavement applications. The incorporation of MK and GGBS reduces energy consumption during cement production, which is widely known as a significant contributor to global warming. It increases the durability of grouting materials under traffic loading.
Improving the ability of asphalt pavement to survive the heavily repeated axle loads and weathering challenges in Iraq has been the subject of research for many years. The critical need for such data in the design and construction of more durable flexible pavement in bridge deck material is paramount. One of new possible steps is the epoxy asphalt concrete, which is classified as a superior asphalt concrete in roads and greatly imparts the level of design and construction. This paper describes a study on 40-50 penetration graded asphalt cement mixed with epoxy to produce asphalt concrete mixtures. The tests carried out are the Marshall properties, permanent deformation, flexural fatigue cracking and moisture damage. Epoxy asphalt mixes performed better on resistance to fatigue and permanent deformation. They also performed significantly better on low-temperature properties and resistance to moisture damage. The addition of 30 percent of epoxy (by weight of asphalt cement) resulted in increase of Marshall stability by 39.8 percent, improve the tensile strength ratio by 22.9 percent, lowering both the rate of permanent deformation by 26.8 percent and the fatigue accumulation coefficient by 53.5 percent, in comparison with control HMA. Based on the above findings, it is recommended to use epoxy asphalt mixes as an optimal material for paving bridges deck in Iraq since it showed good prospects for this application due to the valuable performance and durability improvement.
Urban Heat Island (UHI) phenomena lead to elevated surface temperatures, increased energy consumption, and accelerated pavement degradation. This study aims to enhance the thermal and mechanical performance of asphalt mixtures by incorporating fly ash (FA), a byproduct of coal combustion, as a partial replacement for cement. Asphalt mixtures were prepared using various FA contents (0%, 2%, 4%, 6%) through the dry mixing method. Thermal conductivity was evaluated using the QTM-500 device, while Marshall tests assessed mechanical stability. Results showed that 6% FA reduced thermal conductivity by 20.13%, whereas 4% FA provided the best balance between thermal insulation and structural stability. A clear inverse relationship was observed between thermal conductivity and properties such as bulk density, Marshall stability, and air voids, indicating that FA can enhance insulation without compromising durability. The study focused on the surface asphalt layer, as it serves as the primary interface for solar radiation and heat exchange. Improving its thermal behavior reduces heat transfer to underlying layers, thereby extending pavement lifespan. Moreover, these improvements contribute to mitigating UHI effects, by lowering heat absorption during the day and minimizing heat retention at night supporting sustainable urban development.
Rutting is the most common distress that most Iraqi asphalt pavements suffer from it. Asphalt binders are modified by using additives and polymers to enhance their physical qualities and fulfill the performance demands. Polyphosphoric acid (PPA) has been used in many countries to enhance the physical and mechanical characteristics of asphalt binders and mixtures that can improve the performance of asphalt pavements. In this paper, evaluation of the Iraqi asphalt binder and mixtures performance by using three percentages of Polyphosphoric acid (PPA) (0.4, 0.8, and 1.2) percent by asphalt binder weight and added to (60-70) penetration grade asphalt binder to show the applicability and suitability of using PPA in asphalt pavement in Iraq. Original asphalt binder and modified are subjected to traditional tests which are penetration, ductility, softening point, and viscosity. Results show better performance and enhancement of the physical properties of the modified binder. Other tests are Marshall Stability and wheel track tests. The results of the addition of PPA to the asphalt mixture show increases in the Marshall Stability and enhance the performance of the asphalt pavement mixtures. The wheel track test is applied to the original and modified mixture at two test temperatures 40 ?C and 50 ?C and the results show a decrease in the rut depth when the percentages of PPA increase. It is concluded that %PPA addition will enhance the performance of the Iraqi asphalt pavement and the mixture will be more rutting resistant, especially in high-temperature weather.
Moisture-induced damage in asphalt pavements, is defined by adhesive failure at the binder-aggregate interface and decreased mechanical integrity, severely reduce pavement durability. The research examines the mechanical properties and moisture sensitivity of hot mix asphalt (HMA) enhanced with styrene-butadiene-styrene (SBS) polymer and including reclaimed asphalt pavement (RAP). Laboratory assessments, including indirect tensile strength (ITS) and tensile strength ratio (TSR) tests, were performed on conventional HMA, SBS-modified HMA (4% SBS), and SBS-modified HMA contained 20% RAP. The results indicated that SBS modification significantly improved mechanical and moisture resistance properties, where unconditioned ITS specimens increased by 37.1% and TSR value enhanced by 13.5%. The incorporation of RAP decreased ITS value by about 21 % relative to pure SBS-modified HMA; nevertheless, the SBS+RAP combination still show higher ITS and TSR values than conventional HMA.
The present investigation looked at whether the Bailey approach to aggregate gradation could be used to construct Superpave HMA blends. It also looked at how this approach influenced the rutting performance associated with these mixes and compared it to mixes of asphalt created by Superpave gradations. The current research included four aggregate gradations: both fine and coarse gradations for the Superpave and Bailey gradation procedures. The repeated loading test was utilized to assess the rutting performance. The findings indicated that temperature, stress level, and aggregate gradation all had a significant impact on rutting performance. In contrast to the other three gradations, the third mixture gradation exhibited the least amount of non-reversible deformation. It translates to pavement that is more resistant to rutting and less susceptible to it.
The use of polymers to modify asphalt binder properties in road paving has been increased over the past few decades, producing asphalt mixes that can withstand the growth in traffic load concurrent with development. Therefore, the use of modified asphalt binders has become increasingly popular in recent years to enhance the properties of pavement roads by incorporating various materials, including sustainable ones. This study was conducted as part of a larger study for enhancing asphalt binder properties by using 1%, 2%, 3%, and 4% of sasobit (S) as a warm mix asphalt additive and 1%, 2%, 3%, and 4% of low-density polyethylene (L) as sustainable materials and the mix combination (MC) of both of them. The performance of the treated bitumen was evaluated using conventional tests, including penetration, softening point, and ductility, to assess the physical properties of the mixtures. More advanced tests, including a dynamic shear rheometer (DSR) and a rolling thin film oven test (RTFOT), were conducted. The results show that 4% of Sasobit and 1% of LDPE achieved the optimal values, which significantly enhances the performance of asphalt binders, offering a synergistic blend of sustainability and functionality. LDPE improves the binder’s elasticity and resistance to deformation, while Sasobit lowers mixing and compaction temperatures, boosting workability and energy efficiency. Their combination increases the softening point and reduces penetration and ductility, indicating better high-temperature performance. Viscosity is notably reduced, facilitating easier handling and mixing. Moreover, Sasobit enhances the binder’s resistance to thermo-oxidative aging, with improved ductility retention and thermal stability. The study concluded that using Sasobit and LDPE results in high-performance and durable asphalt mixes that may be highly resistant to permanent deformation and temperature susceptibility.
In Iraq some pavements of the newly constructed highway appear precocious distresses with unfavorable implications especially on the safety and the frugality. Cracking and permanent deformation are main types of these failures. The filler is doubtful to be a master contributor to these failures where its content has a significance effect on the mixture stiffness, and thereby affect the HMA pavement performance. The main objective of this research is to appreciate the influence of different contents of filler on the volumetric properties of asphaltic mixtures thus performance of asphalt mixtures through Comparative Evaluation between conventional Marshall Method and Super pave system. The implementation of a detailed experimental work is carried out to achieve the study objectives through the preparation of asphalt concrete samples using aggregate from Al-Nebaie quarry, (40-50) asphalt cement from Dourah refinery and limestone dust filler with four different contents of (0%, 4%, 8%, and 12%) by weight of the total aggregate. The volumetric properties for each mix design method are evaluated using Marshall Test and the Super pave Gyratory Compacter. The influence of filler contents on the rendering of these mixtures was evaluated.
Hot mix asphalt embedded on "Reclaimed asphalt pavement"(RAP) has the advantages of high technology. Moisture damage is a concern in these mixtures at all service temperatures. Therefore, the performance of this mixture against moisture at all service temperatures was considered a target of this research study. In this way, the effects of humidity on the performance of varieties were investigated using experimental methods including tensile strength ratio (TSR). In the framework of this study, Four different ratios of RAP for each of the surface and bonding layers (10%, 15%, 20%, 25%) and (30,40,50,60)% were added to the hot asphalt mix (HMA) for the two layers respectively to study and find the content Optimal RAP for both layers RAP through Marshall stability and hygroscopic resistance of asphalt mixtures through moisture damage is examined. The ratio (TSR) of the mixtures containing the optimal RAP content is compared with the asphalt mixture without RAP for three fillers and for both layers. The results showed a slight decrease in the tensile strength of the (HMA) that does not contain RAP compared to the asphalt control mixtures containing the reclaimed pavement, where it was found that the percentages were slightly higher and still higher than 80%. The results indicate that in general, Although there are old materials in the hot asphalt mix (HMA) produced from RAP, which include aggregates and bitumen binder surrounding the aggregate particles, the performance of these mixtures and integrations against moisture damage. Because it contains this, it can have results with “hot asphalt mixtures” containing RAP for areas with damage without worry in addition to good natural curbs.
Quality control of riverbank roads is a vital part of the road construction and maintenance process and aims to ensure infrastructure quality, safety, and sustainability. This requires adherence to technical standards, constant auditing, and regular maintenance to maintain the condition of the roads and avoid potential problems. The first step in the quality control of roads is to test the efficiency of the subgrade soil. A geotechnical investigation of subgrade soil under river bank roads is carried out to evaluate the engineering properties of the soil and determine the soil’s ability to bear the loads resulting from vehicle movement and road traffic. This investigation includes analyzing soil samples and laboratory tests to determine soil properties and determine any improvements the soil needs to bear the loads. Soil samples were collected from Al-Kadhimiya Corniche Street. It was dried and subjected to laboratory tests, the soil in this study is classified as poorly graded sand (SP), GS 2.589, the shear strength parameters an internal friction angle of 33 degrees and cohesion of 0.5 kN/m2, and the results of the compaction test indicated that the optimal moisture content was 8.1%, with a maximum dry density was 18.24 kN/m3, CBR 26.04%, and chemical tests (SO3 0.222, pH 8.55, T.SS 0.891, CL 0.085). Software FAARFIELD was used to check pavement design, the thickness design was executed utilising a subgrade CBR value of 26.04%. The subgrade pavement thickness was determined to be 304mm in total. The results agree with the actual design of Al-Kadhimiya Corniche Street, which was recently maintained during the field investigation in 2023.
The properties related to Synthetic fibers such as significant strength, ductility, and durability lead the fibers to be adequate in enhancing the mechanical properties of asphalt concrete mixtures and that indicated by several studies. This paper aims to deliver an overview about the reinforcing influence of synthetic fibers on the mechanical and performance properties of asphalt concrete mixture. This paper surveys the literature on synthetic fibers and their applications in enhancing the mechanical features of asphaltic mixtures. It could serve as a reference for prospective modification and development of asphalt pavement by synthetic fibres. The characteristics of prevalent synthetic fibers are introduced, and their usage in asphalt mixtures is evaluated. A review of fiber surface treatment techniques demonstrates that they can enhance the performance of synthetic fibers in asphalt concrete mixtures, especially on the chemical surface. The article debates how synthetic fibre inclusion influences asphalt concrete mechanical performance, including rutting resistance, tensile strength, water susceptibility, and cracking resistance. The review indicates that using fibers such as aramid, glass, polyester, polyamide, and carbon improves asphalt pavement resistance to permanent deformation.
Soil’s characteristics are essential for the successful design of projects such as airports runway and flexible pavement. CBR (California Bering Ratio) is one of the significant soil characteristics for highways and airports projects. Thus, the CBR property can be used to determine the subgrade reaction of soil through correlations. Many of the soil geotechnical parameters such as compaction characteristics (Maximum Dry Density, MDD; Optimum Moisture Content, OMC), and consistency parameters (Liquid Limit, LL; Plastic Limit, PL; Plasticity Index, PI) can be in charge of changes that happen in soil CBR value. Soaked and/or non-soaked conditions of soils also affect CBR value. Hence, testing soils in a laboratory for CBR calculation is time-consuming that needs notable effort. Therefore, this study aims to generate some useful correlations for soil’s CBR with compaction and consistency parameters for 85 samples of fine-grained soils. The study trials were applied on natural soil samples of various places in Sulaimani Governorate, Northern Iraq. Statistical analysis has been carried out by using SPSS software (Version 28). Soaked CBR is counted, which is important for conditions such as rural roads that remain prone to water for few days. Based on the statistical analysis, there is a significant correlation between LL, PL, PI, MDD, and OMC with CBR as the dependent variable as a single variable equation with R2 of 0.7673, 0.5423, 0.5192, 0.6489, and 0.51, respectively. In addition, the highest value of R2 correlation was obtained between CBR value with consistency and compaction properties as a multiple regression equation with R2 of 0.82. The obtained equations for correlation purposes are successfully achieved and can be used, notably, to estimate CBR value.
This study implements the soft computing techniques such as Artificial Neural Network (ANN) and an adaptive Neuro-Fuzzy (ANFIS) approach. Thus to model the rutting prediction with the aid of experimental uniaxial creep test results for asphalt mixtures. Marshall samples, having Maximum Nominal Size of 12.5 mm, have been selected from previous studies. These samples have been prepared and tested under different conditions. They were also subjected to different loading stress (0.034, 0.069, 0.103) MPa, and tested at various temperature (10, 20, 40, and 55) °C. The modeling analysis revealed that both approaches are powerful tools for modeling creep behavior of pavement mixture in terms of Root Mean Square Error and Correlation Coefficient. The best results are obtained with the ANFIS model.
Chemical additives and polymeric materials, selected for their compatibility and ability to improve asphalt's performance in demanding environments. Key additives, including Polyphosphoric Acid (PPA), Polyvinyl Acetate (PVAC) beads, Maleic Anhydride (MA), and Ethylene Vinyl Acetate (EVA) resin, were mixed in precise ratios with the asphalt binder. These additives were chosen to evaluate their effects on crucial performance indicators, such as the Penetration Index (PI) and activation energy, which measure the material’s thermal stability, flexibility, and resistance to deformation. Results demonstrated that the addition of these materials significantly increased the asphalt’s activation energy by up to 45.44%, enhancing its resistance to temperature fluctuations and providing better stability under various environmental stresses. The Penetration Index (PI) also improved notably, indicating that modified asphalt exhibits greater durability and reduced susceptibility to cracking or deformation under thermal changes. These enhancements contribute to lower road maintenance requirements and support greater energy efficiency in asphalt production and application processes. Compared to neat asphalt, the modified asphalt exhibited superior thermal stability, mechanical resilience, and overall performance, making it suitable for use in diverse climatic conditions. This study provides valuable insights into sustainable asphalt modification techniques, emphasizing the role of polymer and chemical additives in extending pavement lifespan and reducing environmental impact through improved material properties.
Plastic pollution represents a significant global environmental challenge, with millions of tons of plastic waste accumulated annually in landfills and natural ecosystems. The COVID-19 pandemic intensified this issue due to the widespread use of single-use personal protective equipment. As a response to this problem, this study examines the use of recycled polyethylene terephthalate and single-use face masks as additives in porous asphalt mixtures to improve the mixtures’ properties and promote sustainability in pavement engineering. The research aimed to evaluate the combined effect of incorporating recycled polymers into a hybrid system, rather than separately modified mixtures of polyethylene terephthalate and single-use face mask fibers. Laboratory tests indicated that the hybrid mixture exhibited optimal performance, achieving a 34% increase in Marshall stability, a 19% decrease in flow, and a 20% reduction in air-void content. Additionally, permeability decreased by 36%, while remaining within the accepted limit, improving moisture susceptibility, and cantabro abrasion losses decreased by up to 11%, suggesting improvements in cohesion, structure, and durability. The findings demonstrate that hybrid polymer modification offers an environmentally sustainable and high-performance approach for future porous asphalt pavements.
Rutting is considered as the most generated distress in Iraqi roads as a result of the high temperature and excessive traffic load. So, it is essential to utilize polymer modified binder to increase the performance of pavements. The objective of this paper is to assess the effect of aggregate gradation and filler content on the rutting formation of Colored Hot Mix Asphalt CHMA. The HMA was colored by using iron oxide as filler to produce red HMA. Two blends were used: fine and coarse with two different types of filler iron oxide for CHMA and limestone for conventional HMA with two filler content 6% and 10%. Neat (AC 40-50) and modified asphalt (AC 40-50 + 4%SBS) were used. Tests are held on adding 4% Styrene Butadiene Styrene )SBS( by the weight of neat asphalt (AC 40-50) to raise the performance grade by two grades from PG (64-16) to PG (76-16) [1] and [2]. The wheel tracking test is used to assess the rut depth of the CHMA. The test results showed that the using iron oxide with neat asphalt increase the rut depth resistance by 200 and 400 failure load cycles than mixtures using limestone (cycles that mix reach 25 mm rut depth) for fine and coarse mix respectively. Also, the effect of gradation shows that the fine mixture fails at 4000 cycles while the coarse mixture fails at 1800 cycles for 6% limestone mixtures. Increasing the iron oxide content from 6% to 10% leads to increase the failure load cycles by 2200 and 1200 cycles for fine and coarse mixture respectively using modified asphalt. The fine mixture with 10% iron oxide using modified asphalt gives the best performance with 7000 cycles than the coarse mixture with 10% filler content and modified asphalt with 4000 cycles. irrespective the filler and type of binder, the dense mixtures using iron oxide as filler exhibit better resistance to rutting formation than coarse mixtures.
Moisture damage in terms of stripping; and aging surface in terms of raveling and abrasion are among the primary distresses that lead to the deterioration of asphalt pavement, diminishing the overall quality and functionality of road surfaces. This study investigates the impact of using low-cost and locally available waste aluminum scrape powder (WASP) with a particle size ranging from sieves No.8 to No.200. WASP exhibits a high bulk specific gravity and melting point temperature on HMA mixtures, which could also potentially enhance the density and stiffness of modified mixtures. Five quantities of additives 0.5, 1.0, 1.5, 2.0, and 2.5% have been used to enhance the mechanical-durability features. The aggregate sources of AlDoz and AlNibaa'e were chosen, and different mixtures were produced utilizing Marshall and Roller compaction methods. The study's findings indicated that WASP enhanced mechanical-durability characteristics and reduced the asphalt mixture's sensitivity to abrasion, moisture damage, and aging. The optimal amount of WASP was determined to be 1.5%. In addition, based on the influence of the aggregate source and compaction technique, it is visible that the AlNibaa'e source and roller compaction mode provide superior outcomes compared to the AlDoz aggregate source and the Marshall method.
The objective of this paper is find the effect of using iron oxide as a filler on the Marshall stability, flow and the volumetric properties of HMA and compared the results with conventional HMA using limestone dust. Three blends were used: coarse, mid and fine with neat bitumen (AC 40-50). One aggregate type (crushed) with two types of fillers: limestone and iron oxide III (?- ) with three different filler content 6%, 8% and 10%. The Marshall mix design was conducted on the three blends and the optimum binder content is computed for each blend. The Marshall stability test results and the volumetric properties analysis showed that increasing the iron oxide content from 6% to 10% increases the stability about 28%, 17% , 16% for the coarse , mid and fine mixtures respectively. This increment in stability of mixtures using iron oxide related to the increment in specific gravity of the mix (Gmb) by (1.3% to 1.5% about 30 to 50 kg/m3). On the other hand, the flow of mixtures is decreased about (5%) for mixes using iron oxide than the ones that used limestone as filler. The fine blend with 10% iron oxide exhibit the highest stability of 13.3 kN. While the coarse blend stability was 10 kN for the same filler type and content. Generally, the Marshall Test results of HMA using iron oxide as filler showed better resistance to plastic deformation, also produce denser HMA with higher stiffness. On the other hand, the volumetric properties analysis showed lesser values as compared with conventional mixture where the void in mineral aggregates and void filled with asphalt has decreased but within the acceptable limits.
A tack coat is a minimal coating of asphalt cement, cut-back asphalt, or asphalt emulsion to an existing pavement surface between layers to guarantee proper bonding between the two layers and longitudinal and transverse joints. Numerous researchers have assessed interlayer adhesion employing failure-mode behavior tests, such as pull-off, direct shear, and torsion testing. This study aims to quantify the best tensile resistance obtained using three types of cutback asphalt (RC70, RC800 modified with polymer 4.5% & MC70). All are applied on concrete surfaces at a rate of 0.5 L/m². The Proceq DYNA Z16 pull–off tester is used to measure the tensile strength at a rate of 0.25 kN/s. It is found that the average tensile strength of the tack coat materials is (0.319, 0.138, 0.028) MPa, respectively. It is concluded that RC70 has the maximum tensile strength. Also, the different types of solvent affect adhesion strengths; RC70 was Prepared using gasoline, while MC70 used petroleum. Gasoline has greater volatility and thus increased adhesion. Failure strength modes of interior bonding varied between cohesive failure adhesive and adhesive failure.