Marshall Stability Research Articles

Study on the Combined Effect of Municipal Solid Waste Incineration Bottom Ash and Waste Shingle in Hot Mix Asphalt.

This study investigated the positive effect of the combined use of recycled asphalt shingles (RASs) and municipal solid waste incineration (MSWI) bottom ash (B.A.) in asphalt concrete, which contributes to enhanced sustainability in pavement engineering. In addition, unlike traditional approaches that employ individual recycling material in hot mix asphalt (HMA), the combined use of the two waste materials maximizes the mechanical performance of the asphalt mixture. The addition of RAS (with 30-40% aged binder) as an additive generally enhances the strength/stiffness of the asphalt mixture. The high porosity/absorption of MSWI BA results in an additional amount of liquid asphalt binder in the mixture. As an admixture, RAS could supply the additional asphalt binder in the mixture when MSWI BA is used as an aggregate replacement. This research was conducted in two phases: (1) to examine the effect of MSWI BA alone and its optimal asphalt content (OAC), and (2) to assess the combined effect of B.A. and RAS in HMA. Multiple laboratory testing methods were employed for the mechanical performance investigation, including the Marshall stability test, rutting test, and indirect tensile test. The testing results show that the 20% B.A. replacement exhibits the best performance and that it requires an additional asphalt binder of 1.1%. For the combined use of MSWI BA and RAS, 5% RAS shows the best mechanical performance. All mixtures that contain the B.A. and RAS show greater strength than the control specimen (regular HMA).

Innovative Integration of Recycled Plastics for Flexible Pavement Design

Plastic waste is a major problem due to its non-biodegradable nature. Incorporating recycled plastic in road construction enhances mechanical properties effectively. This paper encompasses methods to solve two major issues in Nepal, largely focused in major cities of Nepal: primarily, the management of solid waste, specifically with consideration of used plastics which have engulfed main cities; secondarily, the development of potholes on roads due to heavy traffic weight and some environmental factors such as excessive precipitation and infiltration, flooding conditions. This study inspects the effect of combining waste thermoplastic polymers like High-density polyethylene (HDPE), Polyethylene Terephthalate (PET), and Polypropylene (PP) in flexible pavement design, at various plastic compositions. The plastics were grinded and mixed with the bitumen at a temperature range of 160 °C–170 °C. Various tests such as the Marshall Stability test, Penetration test, Ductility test, and, Softening Point test were carried out to find the resulting modifications from base bitumen. It was observed that the plastic mixed sample upto 10% by weight shows sufficient mechanical properties of pavements. Being a cheap and effective way of improving the capacity of flexible pavement, It is one of the alternative ways to use plastic waste.

Study of Crumb Rubber as Binder Material in Asphalt

Asphalt is a mixture of aggregates, bitumen, quarry dust, and cement. As an addition in hot mix asphalt mixtures, recycled tire rubber known as "crumb rubber" is regarded as an environmentally friendly building practice. The laboratory hot mix asphalt design tests were conducted according to Marshall method procedure. In this study, three different crumb rubber contents (10%, 15%, and 20% by weight of bitumen), and three different bitumen contents (4%, 5%, and 6%) with a penetration grade 60/70 were investigated. The Marshall stability value and durability properties were taken into account in a comparison study between the standard and modified asphalt concrete mixtures. The strength and performance of asphalt mixtures tended to improve with the addition of crumb rubber. As some of the test results were within the acceptable range, the findings indicated that crumb rubber is advised for use as an addition in asphalt mixtures. Besides, the durability of asphalt mixtures also needed to be concerned.

Exploring waste marble dust as an additive in cementitious grouts for semi-flexible pavement applications: Analysis and optimization using RSM

This research aims to explore the potential utilization of waste marble dust (MD) within cementitious grouts for applications in semi-flexible pavements, a hybrid pavement type combining the benefits of both flexible and rigid pavements. MD was used to replace cement (ranging from 0 to 25%), combined with w/c ratios of 0.35 to 0.50, in the formulation of cementitious grouts. The assessment of grout characteristics encompassed evaluations of flowability and compressive strength (7d and 28d curing). Moreover, the microstructural characteristics of cement grouts incorporating MD were scrutinized through Scanning electron microscope-SEM and Energy dispersive X-Ray spectroscopy-EDS analyses. Additionally, response surface methodology (RSM) was used for experimental design, analysis, and the optimization of the factors (MD and w/c ratio). The significance of the model was examined through various statistical indicators. The optimal composition of cementitious grouts was determined using optimization technique within the RSM framework. Furthermore, optimal grout combinations were employed in fabricating semi-flexible mixtures and evaluated for Marshall stability, moisture susceptibility, indirect tensile stiffness modulus, dynamic modulus, compressive strength, and resistance to fuel spillage. The results indicated that an optimal combination of 15% waste marble dust and a 0.40 w/c ratio was identified through optimization techniques within the RSM methodology. Furthermore, Analysis of variance formula-ANOVA outcomes exhibiting a higher R² value (>0.80) and higher adequate precision (>4.0) underscore the significance of the proposed models, revealing a robust correlation between experimental and predicted data. The semi-flexible mixtures also showcase superior performance in terms of Marshall stability, stiffness, dynamic modulus, moisture resistance, and resistance to fuel spillage. Moreover, the integration of waste marble dust in cementitious grouts for constructing semi-flexible pavements not only addresses disposal concerns but also contributes to environmental sustainability.

Marshall Asphalt Mix and Superior Performance Asphalt Mix in Oman: A Comparative Study

The mix design procedure used in Superior Performance Asphalt Pavements (Super-pave) was created by the Strategic Highway Research Program (SHRP) in response to the limitations and empirical approach of Marshall methodology. This study aims to compare the Marshall asphalt mixture design method with the Super-pave asphalt mixture design procedures. Locally available aggregates commonly used in asphalt concrete mixtures in Oman were used. The asphalt mixtures were made with aggregate and asphalt-binder with a penetration grade of 60/70 and PG 64-10. Samples from two mixes were made accordingly. Volumetric properties analysis, flow, Marshall stability, and loss of Marshall stability tests were carried out. According to the study findings, the optimum asphalt composition was 4.5% when utilizing the Marshall methodology and 5.5% when using the Super-pave approach. Furthermore, the Super-pave specimens showed less loss of Marshall stability (22.22%) than the Marshall specimen (30.09%).

Investigation on strength characteristics and mechanism of cold mix based on geopolymerization reaction

Cold mix asphalt is an energy-efficient and eco-friendly pavement material, yet its early strength is deficient. This study investigated the strength augment of cold mix asphalt through modification with geopolymer additives. Macro-strength was assessed via Marshall stability testing under varied geopolymer contents, curing durations, and water immersion conditions. Microscale analysis encompassed fluorescence microscopy to discern geopolymer-asphalt interactions and discrete element modeling to simulate the compression process. Results showed that stability rose and then fell as geopolymer content increased, with an optimal ratio of 4:3 between base asphalt and additive. Stability increased rapidly in the first 3 days of curing and accumulated at a slower rate afterwards. Fluorescence microscopy revealed that geopolymer bonded the asphalt to the aggregate surfaces. Modeling exhibited geopolymer resisted vertical loads and confined the aggregate. In summation, geopolymerization enhances cold mix strength by improving adhesion and generating a rigid 3D network encompassing aggregate particles. The discoveries provide guidance on formulating durable cold mix asphalt utilizing geopolymer additives.

Evaluation of the Stability and Flow of Asphalt Concrete Produced with Waste Brick Tile Powder as a Filler

The utilization of recycled brick tile powder as a replacement for conventional filler in the asphalt concrete mix has been studied in this research. This research evaluates the effectiveness of recycled brick tile powder and determines its optimum replacement level. Using recycled brick tile powder is significant from an environmental standpoint as it is a waste product from construction activities. Sixteen asphalt concrete samples were produced, and eight were soaked for a day. Samples contained 5% Bitumen, 2% to 5% brick tile powder, and conventional stone dust filler. The properties of samples were evaluated using the Marshall test. It was observed that the resistance to stiffness and deformation of asphalt concrete was increased by 99% when the conventional filler was replaced with brick tile powder. The resistance to deformation decreases as the percentage of brick tile powder increases while Marshall stability values increase significantly. At an optimum content of 4% recycled brick tile powder as filler, the Marshall stability is increased by 123%. Based on this investigation, it is established that brick tile powder can be effectively used in asphaltic concrete as a filler. This presents a sustainable solution to waste utilization and pavement performance.

Experimental Investigation of Mechanical and Electromagnetic Performance of Asphalt Concrete Containing Different Ratios of Graphite Powder as a Filler to be Potentially Used as Part of Wireless Electric Roads

This study experimentally investigates the usability of asphalt concrete pavement containing five different ratios of graphite powder (0%, 1.25%, 2.5%, 3.75% and 5% by weight of the aggregate blend or 0%, 25%, 50%, 75% and 100% of the filler content) as a filler to be potentially used as part of wireless electric roads (ER). As part of the study, first, optimum asphalt binder content for the asphalt mixes without graphite powder was determined as 5%. Then, using the determined optimum asphalt binder content, asphalt mixes containing five different ratios of graphite powder as a filler were prepared and their mechanical and volumetric properties based on Marshall mix design methodology were evaluated. As graphite powder ratios in the asphalt mixes increased, their Marshall stability, flow, voids filled with asphalt and unit weight test results mostly decreased but their air content and voids in mineral aggregate test results increased. Possible reasons for this could be: (1) lower bulk specific gravity of graphite powder, (2) higher asphalt absorbance, (3) having greater surface area compared to that of limestone filler, and (4) weak bonds between sheet-like graphite layers. Furthermore, another batch of asphalt mixes containing five different ratios of graphite powder were prepared and tested in the frequency range of 3–18 GHz for their electromagnetic permittivity properties. It was observed in this study that, except for the specimens with 100% graphite powder ratios, transmission magnitudes of all specimens were above 50% up to 8 GHz, indicating that they had comparably high transmission magnitudes so as comparably low tangent loss values. In the frequency range of 3–13 GHz, transmission magnitudes of the specimens with 25% and 50% graphite powder ratios were consistently higher than that having no graphite powder, the ones with 25% powder ratios had the highest transmission magnitudes in most of the cases in this frequency range. Considering the mechanical, volumetric and electromagnetic property test results of the asphalt mixes with five different ratios of graphite powder, it can be concluded that the use of 25% graphite powder ratio (corresponding to 1.25% of the aggregate blend used in the mixes), has a comparably lower negative effect on mechanical and volumetric properties of asphalt mixes and has a positive effect on electromagnetic permittivity properties of asphalt mixes. Asphalt mixes produced with this graphite powder ratio can be considered to be used as part of wireless ER.

Investigation on the Performance of Limestone as Filler on Various Pavement Mixtures

Abstract Additives added to the flexible pavement mixture aim to increase the strength of the pavement. Limestone which is a sedimentary rock consists of the mineral calcium carbonate (calcite) or the double carbonate of calcium and magnesium (dolomite). The use of limestone in pavement mixtures is expected to increase the performance of Marshall parameters. This study aims to determine the suitability of limestone as a filler for 3 types of pavement mixtures, namely Asphalt Concrete Wearing Course, Hot Rolled Sheet and Split Mastic Asphalt. In this study, the limestone used was sourced from Jorong Durian, Nagari Kamang Mudiak, Kamang Magek District, Agam Regency, West Sumatra Province. The tests were carried out using following variations of limestone; 0%, 25%, 50%, 75%, 100% of the total amount of filler in the mixture. The results of the study using limestone as filler obtained at an optimum content of 29% for AC-WC, 22% for HRS, and 82.5% for SMA. In addition, AC-WC pavement was found to the best increase in Marshall stability performance. Therefore, it can be concluded that limestone from Kamang Mudiak is most suitable to be added to AC-WC pavement mixtures.

Evaluation of Bituminous Moisture Damage of High Silica Aggregate

Abstract Moisture damage (Stripping) in Hot Mix Asphalt (HMA) is the loss of adhesive bond between aggregate particles and bitumen due to water action. Most urban roads in Iraq have been exposed to moisture damage failure because of the high silica content in aggregate, this phenomenon led to a decrease in the service life of roads and an increase in maintenance cost. This study used two anti-stripping agents: hydrated lime and Wetfix-BE. Lime was added as a powder to the aggregate in a dosage of 2.0 % of the aggregate weight and Wetfix-BE, a liquid chemical adhesion promoter for hot and warm mix asphalt, was added to asphalt at in dosage of 0.5 % from the total weight of asphalt. The retained Marshall stability, tensile strength ratio, Texas boiling test, and static immersion test are calculated to determine the resistance to moisture damage. The results indicated that both Wetfix-BE and lime could increase Marshall retained stability, tensile strength, and resistance to moisture damage of mixtures, especially at higher condition temperatures. The bitumen modified with Wetfix-BE had better results than bitumen modified with lime for all tests at different temperatures.

A novel approach to warm mix asphalt additive production from polypropylene waste plastic via pyrolysis

The utilization of waste plastics as an additive in warm mix asphalt (WMA), which is an environmentally friendly technology, by pyrolysis method is an emerging concept. In this study, WMA additive was synthesized from char (C) and wax (W) products obtained from the pyrolysis of polypropylene (PP) type waste plastics. Seven different pyrolysis modified bitumen were prepared as PP 6%C, PP 6%C-3%W, PP 6%C-6%W, PP 6%C-10%W, PP 3%C-6%W, PP 1%C-6%W and PP 6%W. Base bitumen and Sasobit® 3% (by weight of bitumen) modified bitumen were used as control groups. The rheological properties of the binders were investigated by Rolling Thin Film Oven, Pressure Aging Vessel, Rotational Viscometer, Dynamic Shear Rheometer and Bending Beam Rheometer tests, and the morphological properties were analyzed by Scanning Electron Microscope, Fourier Transformed Infrared Spectroscopy and Zeta Potential analysis. Asphalt mixture performance characteristics were evaluated by Marshall Design, Hamburg Wheel Tracking and Thermal Stress Restrained Specimen Tests. Binder test results demonstrated that with the addition of PP 6%C-6%W and Sasobit® 3%, the viscosity of bitumen decreased significantly and accordingly the plant temperature reduced by 14ºC and 9ºC. Besides, PP 6%C-6%W modified bitumen performed better than base bitumen at low, medium and high temperatures. Sasobit® 3% improved the high temperature performance of the bitumen. The additive-bitumen modification mechanism involved physical process. Furthermore, the additives were well distributed in bitumen and no agglomeration was observed. WMA-1 (PP 6%C-6%W) and WMA-2 (Sasobit® 3%) have 5% and 9% higher Marshall stability than hot mix asphalt (HMA), respectively. Moreover, the addition of PP 6%C-6%W and Sasobit® 3% increased the rutting resistance of the mixture by 9% and 21%, respectively. Moreover, PP 6%C-6%W improved the low temperature performance of the mixture by decreasing fracture temperature by 3ºC and increasing the fracture strength by 15%. All in all, PP pyrolysis products have strong indicators to become a WMA additive.

Performance of Hybrid Asphalt Mixture through the Stability and Tensile Strength

Introduction: The stability and tensile strength of asphalt mixtures play a crucial role in pavement durability, primarily due to the challenges associated with cracking. This study investigates the utilization of a hybrid asphalt mixture comprising hybrid materials: Palm Oil Fuel Ash (POFA), garnet waste and sawdust to enhance the modified asphalt performance. Aims: The objective is to examine the hybrid materials’ influence towards the mechanical properties of the hybrid asphalt mixture, specifically focusing on the Indirect Tensile Strength (ITS) as well as the Marshall stability test. Methods: To achieve this, hybrid materials were finely ground and sieved to 25µm before being incorporated into the mixture. The Marshall mix design procedure was conducted, utilizing hybrid binders at concentrations of 0% (control), 3% 6%, and 9%. The effects of the hybrid asphalt mixture on stability, flow, stiffness, and ITS were assessed at the optimal binder content. Results: The findings indicate that the hybrid asphalt mixture reveals enhanced Marshall stability, stiffness, flow, and ITS values compared to conventional asphalt mixtures. Notably, hybrid asphalt mixtures with 6% binder concentration demonstrate the most significant enhancement in terms of Marshall stability and ITS. Conclusion: This correlation suggests that the incorporation of POFA, garnet waste, and sawdust as hybrid materials in the hybrid asphalt mixture possesses a positive effect on the overall mechanical properties of the pavement. Highlights: • POFA, garnet waste, and sawdust increased the stability of the hybrid asphalt mixture. • POFA, garnet waste, and sawdust increased the tensile strength of the hybrid asphalt mixture. • Hybrid asphalt mixture performs positively towards flow and stiffness.

Evaluating the Rutting Potential of Asphalt Mixtures with Simple and Practical Tests

The objective of this study was to explore the use of monotonic loading tests (“monotonic tests”) as screening tools to assess the rutting potential of dense-graded asphalt surface mixtures in Virginia. To that end, three monotonic tests—the indirect tensile at high temperature (IDT-HT) test, the rapid rutting (RR) test, and the Marshall stability and flow (MS) test—identified from the literature, were evaluated using 16 plant-produced asphalt mixtures with “A” and “D” designations. The scope of the work also included performing the multiple stress creep and recovery test on the extracted and recovered binders. The results were applied to assess the monotonic tests and the asphalt pavement analyzer (APA) test relative to each other using several performance metrics. The results were also employed to develop performance threshold criteria for the tests being considered. The results showed that the IDT-HT and RR tests can be used to screen the rutting potential of asphalt mixtures meeting the Virginia Department of Transportation (VDOT) mixture volumetric and gradation requirements for A and D mixtures. The initial performance criteria for the IDT-HT and RR tests were established for these mixtures. Based on the results, the IDT-HT test was found to be the most suitable alternative test to the APA test.

Laboratory Evaluation of Porous Asphalt Mixtures with Cellulose Ash or Combustion Soot as a Filler Replacement

Porous asphalt (PA) mixtures have become a common and very useful pavement technology for preventing dangerous driving conditions in wet weather and as a permeable surface in permeable pavement systems due to their capacity to filter water. The increased social awareness of sustainability matters has expanded the interest in reducing the impact of construction materials on the environment, mainly by using recycled materials in their composition and, hence, reducing the depletion of raw materials. In this research, two innovative recycled filler materials, namely, cellulose ash (CA) and combustion soot (CS), have been used as a total filler replacement in PA mixtures to look for improved mechanical strengths and characteristics. Four different filler dosages were assessed for each filler material, and the produced PA mixtures were tested for their particle loss, water sensitivity, freeze–thaw durability, Marshall stability, resilient modulus and permeability in order to obtain a full picture of their performance. The obtained results showed that both filler materials, adequately dosed, can generate PA mixtures that significantly overcome reference mechanical values for PA mixtures that maintain adequate infiltration capacities to satisfy the main international standards, proving to be suitable replacements for conventional filler materials commonly used in asphalt mixture production.

Utilization of Micronized Polyethylene Terephthalate (MPET) as a Filler in Asphalt Pavement

Nowadays, plastic pollution is one of the most critical issues related to sustainability development that need to be solved. Studies indicated that addition of certain amount of recycled plastic from Polyethylene Terephthalate (PET) in asphalt mixture has improved the engineering properties such as marshall stability, moisture resistance, rutting and fatigue resistance. However,the main challenge of direct incorporation of recycled plastic in binder is the thermal incompatibility of two phases which are glass transition and melting temperature.Previous research findings indicated that reduction in particles diameter to micro scale would decrease the PET melting point. Hence, this study investigates the potential of micronized PET from recycled plastic bottle as filler in asphalt pavement. Micronization process at laboratory was carried out to determine the appropriate method prior incorporating it into asphalt mixture. The micronized size of PET incorporated at 0%, 4%, 8%, and 12% by weight of filler is then evaluated for its volumetric properties,mechanical, and adhesion properties. The results showed that the volumetric properties of the asphalt were affected by the presence of micronized PET. The mechanical properties in terms of Resilient Modulus and Indirect Tensile Strength showed increment with addition of micronized PET. Similar trend also observed on adhesion properties. Hence, the findings indicated the potential of utilizing the recycled MPET for local road construction.

Study on the Performance of Phase-Change Self-Regulating Permeable Asphalt Pavement

Under low-temperature conditions in winter, asphalt pavement is prone to cracking, icing and other distresses, which affect its safety and comfort. Therefore, by incorporating phase-change materials into asphalt and conducting relevant performance studies, the aim is to alleviate low-temperature distress and regulate road surface temperature and expand the application of phase-change materials in asphalt pavement. We mixed the selected phase-change materials with different dosages into the matrix asphalt to prepare phase-change temperature-regulating asphalt and tested the four basic indicators: road performance, latent heat characteristics, temperature-regulating performance, and rheological properties of phase-change asphalt and its mixture. The research results indicate that with the increase in phase-change material content, the penetration, softening point, ductility, and dynamic viscosity of phase-change high-viscosity asphalt gradually increase. Under the constant temperature test conditions of −2.5 °C and −5 °C, the surface icing speed of asphalt binder specimens mixed with phase-change materials is slower than that of specimens without phase-change materials. Adding phase-change materials can improve the high-temperature and low-temperature PG grading of high-viscosity asphalt, effectively improving its high-temperature rutting resistance and low-temperature cracking performance. According to the temperature regulation test results, phase-change temperature-regulating asphalt has a certain regulating effect on temperature under low-temperature conditions, which can slow down the cooling rate of asphalt, reduce the thermal conductivity of permeable asphalt mixture by more than 50%, increase the temperature regulation rate by more than 30%, and improve the ice-melting and snow-melting ability by more than 20%. Phase-change materials have almost no effect on the porosity of permeable asphalt mixtures and can effectively improve the water stability, low-temperature crack resistance, and antiflying performance of permeable asphalt mixtures. Their Marshall stability and rutting stability decrease, but still meet the requirements of the specifications. Applying phase-change materials to permeable asphalt pavement can automatically adjust the temperature of the pavement, reduce the cooling rate of the asphalt pavement during cooling, alleviate the problem of snow and ice accumulation on the asphalt pavement in winter, and thereby improve the performance of permeable asphalt pavement against freeze–thaw cycles.

Penggunaan Kapur Palupuh dan Kapur Rao-Rao pada Asphalt Concrete - Wearing Course

Indonesia has the many area of the lime production including in the West Sumatra Province. The use of lime as a filler in asphalt mixtures is expected to improve the performance of asphalt mixtures. There are two types of lime used, namely Palupuh and Rao-Rao limestone. This study aims to see the effect of using these 2 types of lime as a filler on Asphalt Concrete-Wearing Course (AC-WC) pavements mixture. The bitumen used is Pen 60/70. Marshall testing was carried out to see the characteristics of the pavement mixture. From Marshall's testing on a pavement without lime, has an optimum asphalt content of 6.015%. Furthermore, with a variation of lime 0%, 25%, 50%, 75%, 100% by weight of filler for both types of lime gave an optimum lime content yield of 50% with an increase in stability of 12.024% and flow of 19.375% for Palupuh lime. Meanwhile, the use of Rao-Rao lime cannot improve the Marshall stability of the AC-WC pavement mixture

Comparative performance of DG mixes and SMA mixes with waste crumb rubber as aggregate replacement

This research paper presents a comparative study on the performance of asphalt mixes containing waste crumb rubber as an aggregate replacement. Two different mixes namely Dense Graded (DG) and Stone Matrix Asphalt (SMA) with different ratios of waste crumb rubber WCR (0.5%, 1.0%, 1.5%, and 2.0% by weight of aggregate) were produced. The performance tests including, Marshall stability, Marshall Quotient (MQ), tensile strength, tensile strength ratio, and deformation strength in Kim test were carried out on DG and SMA asphalt mixtures. The analyses of test results show that the performance of DG-mixtures is better than SMA-mixtures in term of Marshall stability, and Marshall Quotient and lower indirect tensile strength, and Deformation Strength than SMA mixes. The moisture susceptibility and temperature susceptibility can be reduced by the inclusion of waste crumb rubber in the DG asphalt mixture. A waste crumb rubber content of 0–1.0% by weight of aggregate is recommended for the aggregate replacement of the performance of asphalt concrete mixtures similar to that investigated in this study.

Performance-related methods for the characterization of cold mix patching materials used in asphalt pavements maintenance

Cold mix patching materials (CMPMs) are commonly used as an alternative to hot mix asphalt (HMA) for repairing road pavement potholes, especially in cold and wet seasons. Currently, the acceptance criteria and expectations for the mechanical strength and durability of CMPMs are often compared or related to those adopted for traditional HMA pavements without considering the specific performance characteristics of CMPMs required to ensure their effectiveness. In response to this, the authors proposed innovative solutions derived from pre-existing methodologies to evaluate CMPMs. Several parameters, indicative of CMPMs' structural and functional performance, were measured to optimize the mix design and systematize the quality assurance/quality control (QA/QC) process at various service life stages and under different boundary conditions. Besides the standard Marshall stability and indirect tensile strength (ITS), which were chosen as references, Hubbard-Field and indentation stability tests were reintroduced, suggesting modified procedures specifically tailored to CMPM stability evaluation. Similarly, brush, Leutner, and locking point test methods were customized for analyzing the raveling potential, bonding properties, and workability of the patching materials. The research outcome showed that Hubbard-Field and indentation stability tests provided more accurate stability assessments, even for materials unsuitable for testing using Marshall stability and ITS methods. Modified brush and Leutner tests effectively replicated real-world conditions, enhancing the relevance of laboratory findings to practical applications. Furthermore, the locking point method enabled mixture workability classification. These findings contribute to a better understanding of CMPM performance and can inform more targeted and effective road repair strategies.

Effect of differently treated recycled concrete aggregates on Marshall properties and cost-benefit of asphalt mixtures

Marshall properties are one of the major requirements for designing hot asphalt mixtures. These properties need to be evaluated to make sure that asphalt pavement performs well over its service life. The evaluation of the Marshall properties of asphalt mixtures containing coarse recycled concrete aggregates (RCA) was the study's main target. RCA properties differ from virgin aggregate in the presence of cement mortar. To improve RCA properties, two methods were adopted. The first, termed pre-soak treatment, consisted of soaking RCA in acetic acid for 24 hours at a concentration of 0.1 M. The second one, termed mechanical treatment, involved placing RCA inside the Los Angeles machine with balls and running it for 500 cycles. RCA was incorporated into asphalt mixtures at percentages 20, 40, 60, 80, and 100% of coarse virgin aggregate. The results of the study showed that replacing virgin aggregate with RCA led to economic feasibility. Despite the amount of asphalt binder increasing as coarse RCA content increased, the characteristics of HMA were not significantly altered except for Marshall stability. The maximum increase in Marshall stability happened in the mixture containing 60% untreated RCA; it was 14.78% greater than the control mixture.