Nominal Maximum Aggregate Size Research Articles

A multi-gradient analysis of microscopic void characteristics' influence on the mechanical properties of open-graded friction course bituminous pavement

The mechanical properties of the open-graded friction course (OGFC) bituminous pavement are tied to its microscopic void structure, but multiple void parameters influence void formation and distribution. Solely using air voids as an indicator of pavement stability is challenging. Thus, a multi-gradient analysis of void structure factors is vital for advancing OGFC pavement's mechanical property research. This study used computerized tomography (CT) and digital image processing (DIP) to gather data on void structure distribution, size, and complexity in OGFC bituminous mixtures. Mechanical experiments assessed high-temperature deformation, low-temperature cracking, and water damage resistance. Analysis of void parameters' influence led to a predictive model for mechanical property in OGFC mixtures. The study found that as air voids increase within the 18 %–24 % range, both equivalent void diameter and void fractal dimension increase, while void count decreases. Conversely, coarser gradation and a larger nominal maximum aggregate size (NMAS) lead to increased equivalent void diameter but decreased void fractal dimension, reducing void complexity. The mechanical properties of OGFC mixtures decline with rising air voids but improve with coarser gradation and larger NMAS. The predictive model highlights the void fractal dimension and NMAS as critical indicators, with other factors showing weaker influence or multicollinearity issues that are unfit for model fitting. The findings could provide useful references for the structural design, property evaluation, and quality control of OGFC bituminous pavements in actual road construction.

Influence of Specimen Geometries on the Viscoelastic Properties of Bituminous Mixtures in Torsion

A standard test method for determining the linear viscoelastic properties of bituminous mixtures in torsion prescribes the use of a dynamic shear rheometer. The method uses a prismoidal specimen (rectangular cross section) sliced from a Superpave gyratory compacted sample. However, the geometry utilized in the standard is a non-axisymmetric cross section, which leads to the development of warping stress when the specimen is tested in torsion using a dynamic shear rheometer. On the other hand, axisymmetric geometry, such as cylinder (circular cross section), does not warp when subjected to torsion. This study investigates the influence of the two specimen geometries, namely prismoidal and cylindrical, on the linear viscoelastic properties of bituminous mixtures in torsion. The specimens are obtained from a bituminous mixture with a nominal maximum aggregate size of 13.2 mm, and statistical analysis is carried out to determine whether the material constitution in the specimen geometries is identical. A frequency sweep experiment is conducted at 10, 20, and 30°C with a constant strain amplitude of 0.001% in the frequency range of 0.01 Hz to 20 Hz. The absolute shear modulus of the prismoidal specimens is found to be higher than that of cylindrical specimens because of warping stresses in prismoidal specimens. It was seen that the effect of warping stress is greater at higher temperatures and lower frequencies. Correction factors are used to correct the absolute shear modulus of prismoidal specimens. These findings highlight the importance of considering correction factors for warping when characterizing prismoidal bituminous mixtures in torsion.

Assessing the Viability of Waste Plastic Aggregate in Stone-Modified Asphalt Concrete Mix for Bus Rapid Transit Pavement Maintenance

This research takes on a scientific problem originating from the pervasive deterioration observed in the pavements of Bus Rapid Transit (BRT) systems, which presents formidable challenges to their durability and imposes significant financial burdens on BRT organizations. While wear and tear on BRT pavements is a widely recognized concern, there exists a pronounced deficiency in sustainable solutions to address this issue comprehensively. This study endeavored to bridge this scientific gap by exploring the option of incorporating waste plastic aggregate (WPA) and recycled asphalt pavement (RAP) into the pavement material. The series of comprehensive investigations commenced with an assessment of modified binders. We identified a 25% extracted RAP binder as the most suitable candidate. Our research next determined that a 4% WPA content offers optimal results when used as an aggregate replacement in a stone-modified asphalt concrete mix, which is further refined with a 13 mm nominal maximum aggregate size (NMAS) gradation, resulting in superior performance. Under double-load conditions of the Hamburg Wheel Tracking test, rutting in the 10 mm NMAS mixture rapidly increased to 9 mm after 12,400 HWT cycles, while the 13 mm NMAS mixture showed a more gradual ascent to the same critical rutting level after 20,000 HWT cycles (a 61% increase). Real-world application at a designated BRT station area in Seoul reinforced the findings, revealing that the use of 13 mm NMAS with 4% WPA and RAP significantly improved performance, reducing rutting to 75 µm and enhancing pavement resilience. This configuration increased Road Bearing Capacity (RBC) to 5400 MPa at the center zone, showcasing superior load-bearing capability. Conversely, the 10 mm NMAS mixture without RAP and WPA experienced severe rutting (220 µm) and a 76% reduction in RBC to 1300 MPa, indicating diminished pavement durability. In general, this research highlights the need for innovative solutions to address BRT pavement maintenance challenges and offers a novel, environmentally friendly, and high-performance alternative to traditional methods.

Macrotexture Prediction for Road Mixtures with Low Nominal Maximum Aggregate Size

Macrotexture Prediction for Road Mixtures with Low Nominal Maximum Aggregate Size

Life cycle assessment of energy consumption and carbon emissions of a green maintenance material for asphalt pavement: Warm mix OUFC-5

The warm mix (WM) 4.75 mm nominal maximum aggregate size (NMAS) Open-Graded Ultra-thin Friction Course (WM OUFC-5) represents an innovative green preventive maintenance material boasting commendable road performance. Its potential to address carbon peak and neutrality goals objectives has garnered significant interest. This study aims to quantify the energy-saving and carbon reduction benefits of WM OUFC-5. Three commonly used preventive maintenance materials, including thin overlay (TO), synchronous surface dressing (SSD), and micro-surfacing (MS) in Hubei province, China, were selected as a control group. Employing the process-based life cycle assessment (PLCA), an evaluation framework and computational model was devised to gauge the energy and carbon footprints of each maintenance material. A comparative analysis was then conducted to identify the primary energy and emission contributors of WM OUFC-5 across different life-cycle phases. The results indicate that WM OUFC-5 is a highly sustainable material with low energy consumption and carbon emissions, with its energy consumption being merely 47.2% of TO and 50.7% of MS. And its carbon emissions are 64.3% lower than TO, 26.9% lower than MS, and 49.8% lower than SSD. Throughout the maintenance life cycle, the raw materials production and processing phase and the mixture production phase emerged as the predominant contributors to energy consumption and carbon emissions. The study also provided actionable recommendations to curtail energy and carbon footprints across all phases of the asphalt pavement maintenance life cycle. This study provides support for the low-carbon development of asphalt pavement maintenance in China.

Microscopic void characteristics of OGFC in Sponge City and its effect on noise reduction performance using X-ray CT

This study aims to evaluate how material composition and microscopic void characteristics affect the noise reduction performance of open-graded friction courses (OGFC). X-ray computed tomography (CT) and image processing were employed to analyze the microscopic void characteristics of different OGFC mixtures. Sound absorption tests were conducted, revealing a direct link between OGFC's noise reduction performance and its microscopic void features, particularly connected air voids and void area. This relationship is linear, with every 1 % increase in air voids resulting in a 4.93 % average sound absorption coefficient increase. When air voids are similar, coarser gradations and larger nominal maximum aggregate sizes (NMAS) correspond to higher noise reduction levels, particularly for high-frequency noise. The most significant impact on microscopic void properties comes from the 9.5 mm and 4.75 mm mesh sizes, followed by 1.18 mm, while the 2.36 mm sieve exhibits a weaker correlation. These findings are crucial for enhancing OGFC pavement's noise-reduction capabilities, especially in Sponge Cities, and extending the acoustic lifespan of pavement.

Exploring potential of Marshall-RT as simple performance test to evaluate rutting resistance of asphalt mixtures

ABSTRACT This study explored a new simple monotonic Marshall rutting test (Marshall-RT) to evaluate the rutting resistance of asphalt mixtures. The Marshall-RT test setup combines the Marshall fixture (at the bottom) and the IDT fixture (at the top). The rutting resistance of asphalt mixtures was evaluated using peak load (Pmax) and work done for the deformation damage obtained from the load-displacement curve. Nine plant-produced asphalt mixtures having different types of binders (unmodified, crumb rubber modified binder (CRMB)), and polymer modified binder (PMB)) and gradations having different nominal maximum aggregate sizes (NMAS) were evaluated. The Marshall-RT test parameters (i.e. Pmax and W P m a x ) have shown a strong correlation with fundamental (i.e. Flow Number (FN)), simulative (i.e. Hamburg wheel tracking test (HWTT)), and simple monotonic (i.e. Ideal rutting test (IDEAL-RT)) rutting tests. Moreover, the Marshall-RT test has shown good repeatability, the highest differentiation potential, and consistent ranking with other rutting tests. Furthermore, for high traffic levels (i.e. 100 MSA (Million Standard Axle)), at 50°C preliminary minimum threshold criteria were proposed for Marshall-RT (Pmax and W P m a x ), and IDEAL-RT (RTIndex) as 5 kN, 14 kN-mm, and 90, respectively, to avoid premature rutting failure. Thus, the newly developed monotonic Marshall-RT test can also be used as a surrogate simple performance test to estimate the rutting potential of asphalt mixtures during the mix design and plant production phases as quality control (QC)/quality assurance (QA).

Evaluation of cracking resistance of asphalt concrete under long-term aging condition

Cracking is one of the primary distresses in asphalt pavements under traffic loading and climate. Asphalt cracking can be caused by aging asphalt binders in production, transportation, construction, and exploitation. Therefore, it is very necessary to study the influence of aging on cracking resistance for asphalt concrete. This paper initially evaluated the cracking resistance of asphalt concrete with a nominal maximum aggregate size of 12.5mm (AC 12.5) under long-term aging conditions. Based on the laboratory experiments, the study evaluated the required technical parameters of 60/70 binder, PMBIII binder, and AC 12.5 considering long-term aging conditions. Test results indicated that the aging of asphalt binder can significantly affect the cracking resistance of asphalt concrete.

Quantification of inhomogeneity and anisotropy of bituminous mixtures using biaxial experimental data

Most of the existing mechanical characterization test methods and the analytical models for bituminous mixtures are developed based on the assumption of homogenous and isotropic material properties. However, the extent to which such assumptions hold good for bituminous mixtures is not very clear. A biaxial testing scheme in indirect tension mode can come in handy to collect the experimental data at different test temperature regimes. In this study, a bituminous mixture with a nominal maximum aggregate size (NMAS) of 13.2 mm is used to fabricate cylindrical test specimens with 150 mm diameter and 63.5 mm thickness for conducting the repeated load indirect tension (IDT) test. The input load level is selected as 5 to 13 % of the indirect tensile (ITS) failure load in the form of a haversine pulse of 0.1 s loading and 0.9 s rest period. Such loading is applied on zero-degree and ninety-degree orientations of the specimen. The resulting deformations in different directions are measured using linear variable differential transducers (LVDT) attached to both diametral faces of the specimen. The response of the bituminous mixture specimen is captured at three different temperatures of 20, 25, and 30 °C using two different gauge length (half and quarter gauge of the total diameter). A new framework is introduced in this study to evaluate the extent of inhomogeneity and anisotropy of bituminous mixtures. The deformation response of the test specimen captured in the same orientation at different diametral faces is compared to evaluate the extent of inhomogeneity. The extent of anisotropy is evaluated by comparing the deformation response of the test specimen captured at different orientations within the same diametral face. A 15 % variation in the average peak deformation is chosen as the demarcation for determining the extent of inhomogeneity and anisotropy. From this investigation, it is observed that half gauge length experimental data exhibits homogenous and isotropic behavior for all three test temperatures. The quarter gauge length data exhibit similar behavior at 30 °C, whereas it is observed as homogenous and anisotropic at the other two test temperatures.

Study on the possibility of using steel slag in Ba Ria Vung Tau for the Stone Mastic Asphalt (SMA)

Currently, the source of materials using to construct transport infrastructure is increasingly scarce in Vietnam. Therefore, it is very necessary to study solutions for utilizing steel slag as aggregates for asphalt concrete. This paper evaluated initially the possibility of use of 50% and 75% steel slag in Ba Ria-Vung Tau replacement aggregates for stone mastic asphalt with a nominal maximum aggregate size of 12,5mm (SMA 12,5). Based on the laboratory experiments, the study evaluated the required technical parameters of SMA 12,5 in terms of drain down characteristic, Cantabro abrasion loss, Marshall stability, Marshall stability ratio, and rutting according to TCCS36:2021/TCDBVN. Test results indicated the possibility of use of 50% steel slag replacement aggregates for SMA 12,5 in pavement construction.

Sustainable and Cost-Effective Development of Pervious Paver Block made with RHA (Rice Husk Ash) and RAP (Recycled Asphalt Pavement)

Abstract: The study's goal is to create cost-effective and eco-friendly pervious paver blocks by reusing asphalt pavement at 0%, 50%, and 100% weight ratios. Building permeable paver blocks using RHA (Rice Husk Ash), an industrial waste product with a cementous ratio of 10% to 20% by weight, is a step toward a more eco-friendly and cost-effective future. Both recycled asphalt pavement (RAP) aggregates and newly quarried "fresh aggregates" (FA) were employed in this investigation. Bituminous concrete (BC) pavement that was 2 years old and Stored in dumping yard besides the Rahul ware house in Gwalior, Madhya Pradesh on Srinagar – Kanyakumari Highway yielded RAP with a nominal maximum aggregate size of 13 mm. The production of PCPB has been standardized. This technique is known as the "cement paste encapsulating aggregate blending method." “After adding all of the aggregate and 20–25% of the total calculated water content, the concrete mixer was operated for 15-20 seconds”. The RP overseas in Lohgarh (M.P.) provided the rice husk ash that was used in the project. Rice husk ash (RHA) has a high specific gravity of 2.10 and a low bulk density of 0.781 g/cc, making it highly reactive and pozzolanic. RHA is recommended for use in both plain and reinforced concrete by the IS 456-2000 Indian Standard code of practice. The results of the investigation demonstrated that G2 graded mixes had higher porosity than G1 graded mixes. The results showed that CL values were minimal at w-c ratios of 0.35. The cement paste at this water-to-cement ratio is strong enough to bind the aggregate particles together, which explains why this occurs. In comparison to the conventional approach, the optimal replacement level of RHA results in block costs that are reduced by 7.5% for 0 RAP and 10% RHA, 15% for 0 RAP and 20% RHA, 20% for 50% Rap and 10% RHA, 27% for 50% RAP and 20% RHA, 33.2% for 100% RAP and 10% RHA, and 40.62% for 100% RAP and 20% RHA. The conclusion is that RHA-made paver blocks are reliable and cost-effective. The conclusion is that paver blocks made by RHA are durable and affordable

Influence of aggregate source and size on the shear behavior of high strength reinforced concrete deep beams

This paper aims to examine the influence of coarse aggregate characteristics, including toughness and nominal maximum size of aggregate on the RC deep beams’ shear behavior made with and without shear reinforcement. Nine deep beams were prepared with three coarse aggregate types (i.e., limestone, steel slag, and quartzite) having different toughness properties and two nominal maximum aggregate (10 mm and 20 mm) sizes, which were examined under four-point bending. The experimental findings showed that the deep beams exhibited shear failure caused by diagonal shear cracks initiated between the supports and the loading point. Utilizing bigger coarse aggregate size has led to reducing the number of shear cracks. The deep beam stiffness was not impacted by the change in coarse aggregate toughness, aggregate size, or the use of shear reinforcement. For the beams without shear reinforcement, increasing the nominal maximum coarse aggregate size improved the deep beams normalized shear strength. This improvement depended on the coarse aggregate’s toughness with the toughest aggregate (steel slag) showing the greatest improvement. Moreover, using shear reinforcement has contributed to improving the deep beams’ normalized shear strength. The normalized shear strength increased from 6% to 16% compared to deep beams without shear reinforcement.

Improvement of Computational Efficiency and Accuracy by Firefly Algorithm and Random Forest for Compressive Strength Modeling of Recycled Concrete

It is an important direction for the sustainable development of pavement to mix the discarded concrete blocks with gradation according to a certain proportion after crushing, cleaning and other technological processes, partially or completely replace aggregate, and then add cement, water, and so on to make recycled concrete for pavement paving, but the traditional evaluation model for the compressive strength (CS) of recycled concrete cannot meet the requirements of efficient calculation. To address such issues, the present research proposed to apply the firefly algorithm (FA) to optimize the random forest (RF) model. The results were demonstrated by comparing the consistency of predicted and actual values, and also by analyzing the correlation coefficient (R) and root-mean-square error (RMSE). Higher R values (0.9756 and 0.9328) and lower RMSE values (3.0752 and 6.4369) for the training and test sets present the reliability of the FA and RF hybrid machine learning model. To understand the influence law of input indexes on the output index, the importance and sensitivity of variables are further analyzed. The results displayed that effective water-cement ratio (WC) and nominal maximum recycled concrete aggregate size (NMR) have the greatest impact on the output variable, with importance scores of 2.5947 and 2.4315, respectively, while the change in the recycled concrete aggregate replacement rate (RCA) has a weak influence, with an importance score of 0.4695. Introducing FA to RF for the compressive strength modeling of recycled concrete can significantly improve the computational efficiency and accuracy.

Laboratory Investigation of Open Graded Friction Courses with Different Binder Grades and Aggregate Gradations

This study investigates the effectiveness of the volumetric mix design procedure used by the New Mexico Department of Transportation based only on the tensile strength ratio (TSR) test for designing open graded friction course (OGFC) materials. It also evaluates the effects of different binders (or binder grades) and aggregate gradations on the performance of OGFC materials. Nine OGFC mixes were produced using three different binders (PG 64-28+, PG 70-28+, and PG 76-22+) and three different aggregate gradations (two of 9.5 mm nominal maximum aggregate size [NMAS] and one of 12.5 mm NMAS). Next, a thorough laboratory investigation was conducted to evaluate their various performances. This study found that the traditional volumetric mix design based solely on the TSR test cannot ensure adequate durability performance. The PG 64-28+ OGFCs, for example, met all the volumetric and TSR requirements during mix design but performed poorly in all performance tests. This suggests that additional performance testing for OGFCs is required to ensure adequate longevity. Cantabro abrasion and semi-circular bending tests are found to be useful in characterizing the durability and moisture conditioning, and the fracture performances of an OGFC, respectively. Furthermore, a new test is proposed for evaluating the durability performance of an OGFC in wet conditions using the Micro-Deval device. According to this study, OGFC's durability and fracture performance improves as the grade of binder used increases. The OGFCs prepared with aggregates of smaller NMAS outperformed the OGFCs prepared with larger NMAS aggregate in both durability and fracture tests despite having similar asphalt contents.

Experimental investigation of superpave mixtures for optimum and rich mixes

Population growth and economic status in the nation lead to improved infrastructure, and thereby, the number of commercial vehicles on the road increases, leading to the early deterioration of pavement layers. The structural failures of the pavement demand rehabilitation and reconstruction of the pavement layers, leading to significant construction costs. The distress in the pavement layers observed can be minimized by using superpave mixtures. This paper compares the volumetric and mechanical properties of optimum and rich superpave mixes using viscosity grade (VG) 40 as the binder. Nominal maximum aggregate sizes (NMAS) of 25 mm and 19 mm, abbreviated as G1 and G2, respectively, were used. The mechanical properties, including fatigue test, Indirect Tensile Strength (ITS), and moisture susceptibility, were performed on both optimum and rich mixes, and a comparative analysis of mixes was done. G1 graded mixes showed better performance in all aspects compared to G2. Rich mixes were observed to have more fatigue resistance than the optimum mixes, while optimum mixes have better ITS.

Stiffness evaluation of Forta Fibre Reinforced Asphalt Concrete (FRAC) mixture under different pulse repetition load

Pavement structure can be designed either as a flexible or a rigid pavement based on its structural behaviour, with flexible pavements being frequently favored due to its advantages. One of the major problems that normally occurred in road construction was pavement distresses due to the quality of the materials. Numerous studies were carried out to explore sustainable ways to improve the pavement performance especially on modification of the asphaltic concrete in construction phases. This paper investigates the effect of Forta-Fi fiber on stiffness performance of hot mix asphalt mixture (HMA). In this respect, conventional asphalt binder grade 60/70 and Nominal Maximum Aggregate Size (NMAS) 12.5mm were used in the preparation of asphalt mixture specimens as specified in Superpave mix design method. Performance of modified samples incorporating 0.3, 0.5 and 0.7% of total mixture were evaluated for resilient modulus accordance to ASTM D4123 using Universal Testing Machine (UTM). The samples were tested at 25°C and 40°C with pulse repetition period 1000ms, 2000ms and 3000ms to simulate low, medium and high volume of traffic. As a result, the resilient modulus values of modified asphalt mixture improved 38% with 0.3% additive of Forta-Fi at 25°C with 3000ms pulse repetition period, while at 40°C with 3000ms pulse repetition period improved 23% with 0.5% additive of Forta-Fi. Based on these studies, the addition of fibers reinforcement into the asphalt mixture has a significant effect on resilient modulus of fibers reinforced asphalt mixture.

A laboratory evaluation of factors affecting rutting resistance of asphalt mixtures using wheel tracking test

Rutting is one of the most common distresses in early damage to asphalt pavements. It can raise the risk of ride safety issues, accelerate pavement deterioration, and increase maintenance costs. To investigate the factors that affect the rutting resistance of asphalt mixtures, internal factors (such as aggregate gradation, asphalt content, and layer thickness), external factors (including temperature and traffic loading), and human factors (such as compaction degree) were tested using wheel tracking tests. The test results showed that the rutting resistance of asphalt mixtures can be improved by designing a tightly interlocked aggregate skeleton using the Bailey method's primary control sieve, using an optimal asphalt content, achieving sufficient compaction, maintaining a layer thickness of 2.5–3 times its nominal maximum aggregate size, using an asphalt softening point higher than the pavement temperature, and avoiding overloaded vehicles. In highly rutted areas, it is recommended to use a stone mastic asphalt with a stable aggregate skeleton matrix and styrene-butadiene-styrene modified asphalt with a softening point higher than the highest pavement temperature.

Balanced Mix Design Benchmarking of Asphalt Mixtures Produced in Vermont

Performance testing is an important tool to complement volumetric properties for improving asphalt pavement performance. Vermont Agency of Transportation (VTrans) began evaluating the Hamburg wheel-tracking test (HWTT) in 2015, the Illinois flexibility index test (I-FIT) in 2018, and the indirect tensile cracking test (IDEAL-CT) as another index-based test to investigate along with the I-FIT, as a step toward balanced mix design (BMD) implementation. An increase in the use of recycled materials in asphalt mixtures produced in Vermont was anticipated in their Standard Specifications for Construction. This study is an attempt in this direction. The tests were conducted on reheated plant mixtures sampled from paving projects in Vermont and the results were analyzed to (1) develop baseline rutting and cracking performance; (2) evaluate the effects of mixture properties on performance test results; (3) compare IDEAL-CT results and I-FIT results; and (4) compare performance test results with specification criteria proposed by VTrans for evaluating the rutting and cracking resistance of asphalt mixtures. Several mixture properties, viz., nominal maximum aggregate size (NMAS), binder grade, binder content, and recycled content, were found to have significant effects on mixture rutting and cracking resistance. The test results showed a direct correlation between FI and CTindex for the dataset of VTrans mixtures. The information from this research will help VTrans to achieve its goal to move beyond the use of volumetric properties for asphalt mixture design and acceptance and serve as an example for other agencies in exploring the implementation of BMD for improving asphalt pavement performance.

Fatigue and stiffness characteristics of asphalt mixtures made of recycled aggregates

This research studies the stiffness characteristics and fatigue life of several asphalt mixtures made of recycled glass, reclaimed asphalt pavement (RAP), and recycled concrete aggregate (RCA). Experiments were carried out at 5–35 °C, loading frequencies of 0.1–20 Hz, and at two microstrain levels of 200 and 400 µm/m. To date, the effect of extensive parametric combinations of loadings, microstrain levels, and temperatures on asphalt mixtures made entirely of recycled materials (RM) has not been undertaken. The findings exhibited superior stiffness characteristics and improved fatigue life of some RM mixtures compared to control mixtures. The next step of this study included the optimization of three existing fatigue life prediction models. In addition, a prediction model was developed based on nominal maximum aggregate size (NMAS), percentage of RCA, and percentage of RAP in the asphalt mixture. The optimized models resulted in a much higher coefficient of determination (R2) and P-value (likelihood) in the statistical T-test compared to the existing prediction models utilized in this study. The developed model yielded R2 values close to 0.99 between measured and predicted fatigue life, indicating an enhanced accuracy in the prediction. Comparison of the estimated dissipation energy of mixtures supported and validated the fatigue testing outcomes.

Compaction Effort Evaluation of Crumb Rubber Modified Hot Mix Asphalt

The primary goal of this study was to obtain the same performance from an asphalt mixture made using a Marshall impact hammer (MIH) as from asphalt made using a Superpave gyratory compactor (SGC). This was due to the expense of Superpave equipment compared with Marshall equipment. A wet process was used to blend the CR with PG 70-16 asphalt. A crushed stone aggregate was used with a 19 mm nominal maximum aggregate size, and the samples were prepared using an SGC and an MIH. The results show that nine percent CR was determined to be the optimum crumb-rubber content (OCRC). In addition, the SGC provided excellent performance in Marshall stability, density, tensile strength, and compressive strength at different numbers of blows and gyrations compared with the MIH. Moreover, the MIH required approximately 21, 21, 18, and 24 extra blows to obtain the same stability, density, tensile strength, and compressive strength, respectively, as the SGC at the design number of gyrations (Ndesign). Furthermore, modified mixtures at the OCRC increased the compressive strength in the range from 16 to 48 percent and had higher values on the index of retained strength than unmodified mixtures. As a result, they provided mixtures with less susceptibility to moisture damage. The significance of this study is that asphalt that performed the same as Superpave samples was obtained using only Marshall equipment.