Increase In Reclaimed Asphalt Pavement Content Research Articles

Experimental and predictive study of self-compacting concrete containing reclaimed asphalt pavement

This work focuses on the reuse of reclaimed asphalt pavement (RAP) in the production of self-compacting concrete (SCC) for usage in the construction of rigid pavements. The article first describes an experimental study where five SCC mixtures incorporating 0%, 20%, 40%, 60% and 100% volumetric substitutions of natural aggregates by RAP were formulated. Several characterisation tests in the fresh and hardened states were then performed. The results of all performed tests showed that RAP has a slight negative effect on SCC performance in the fresh state. The most significant reduction observed does not exceed 18% for slump-flow and 10% for L-shaped box values when total substitution is applied. Furthermore, the mechanical properties noticeably decrease with an increase in RAP content, with reductions of up to 37% in 28-d compressive strength and 23% in 28-d indirect tensile (IDT) strength observed in the case of full replacement. However, it is possible to formulate SCC mixtures even with 100% RAP substitutions and meet specifications for rigid pavement construction. In addition, modelling of the various mechanical characteristics made it possible to find out the reason behind the reduction in these properties with RAP content. In fact, the thin bitumen film around RAP particles weakens their surface adhesion with the hydrated cement paste. With the intrinsic RAP properties found, the hardened-state characteristics of any other SCC mixture incorporating RAP could be predicted.

Study on low temperature crack resistance of warm-mixed recycled SBS modified asphalt mixtures

In view of the cold winter in northern China and the large temperature difference between day and night, the asphalt pavement has been in low temperature service for a long time, in addition to experiencing the aging effect of water and salt erosion, jointly leading to a particularly serious pavement cracking phenomenon. Therefore, a quantity of Reclaimed Asphalt Pavement (RAP) is produced for the repair and renovation of old roads. Faced with the problems of inadequate reuse rate of RAP and high energy consumption of thermal regeneration, it is of great practical significance to explore the technology of warm mix regeneration. In order to study the adaptability of recycled SBS modified asphalt mixtures to low temperature after complex environmental erosion (long-term aging, water freeze-thaw cycle, and salt freeze-thaw cycle), two mixing methods, including hot mixing and warm mixing, were selected, and a Semi-Circular Bending Test was performed. SCB and Digital Image Correlation (DIC) techniques were used to evaluate the low temperature properties of recycled asphalt mixtures by fracture toughness, fracture energy and horizontal strain density damage. Combined with an Atomic Force Microscope (AFM) test, the microscopic analysis of recycled asphalt was carried out to verify the mechanism of low temperature cracking. The results showed that the low temperature cracking resistance of the reclaimed asphalt mixtures with warm mix was slightly worse than that with hot mix. The overall low temperature cracking resistance of the reclaimed SBS modified asphalt mixtures decreased with the increase in RAP content. The low temperature performance of the warm-mixed reclaimed asphalt mixtures deteriorated greatly when the RAP content was 80 %. The influencing factors of environmental conditions on the low temperature cracking resistance of the warm-mixed recycled SBS modified asphalt mixtures were listed as below: long-term aging > salt freeze-thaw cycle > water freeze-thaw cycle. The influence of salt on the stress field of crack tip and the microstructure of recycled asphalt after freeze-thaw was greater than that of water erosion. The changes of the microscopic adhesion were in good agreement with the macroscopic test results, which could be employed as the index evaluating the low temperature crack resistance of the warm-mixed SBS modified asphalt mixtures. The addition of warm mixing agent would play a positive role in the low temperature crack resistance of recycled asphalt mixtures with a RAP content of less than 60 % to a certain extent, so warm-mixed recycled asphalt mixtures were more suitable for the application in northern areas.

Low-temperature fracture resistance of plant-mixed heat recycled asphalt mixture based on SCB

To investigate the low-temperature crack resistance of plant-mixed heated recycled asphalt mixture, we conducted a semi-circular bending (SCB) test to analyze the effects of the reclaimed asphalt pavement (RAP) content, salt concentration, and loading rate on the crack resistance at −15 °C. The experimental results show that the fracture energy (G f) of the recycled asphalt mixture decreases with an increase in RAP content and salt concentration but increases with an increase in loading rate. When the RAP content is 0%, the Gf of the specimen reaches its maximum value, while when the RAP content is 50%, Gf reaches its minimum value. When the loading rate is 10 mm s−1, the destruction of coarse aggregates in the specimen is much greater than the destruction mode at a loading rate of 2 mm s−1. Meanwhile, as the RAP content increases, the influence of chloride salt on the low-temperature crack resistance of the recycled asphalt mixture fluctuates. According to the quadratic fitting of RAP content and G f, it can be concluded that a lower loading rate is more helpful in analyzing the degradation mechanism of reclaimed asphalt mixture by salt, and a loading rate of 5 mm s−1 ha−1s−1 a significant impact on the degradation trend of the recycled asphalt mixture. Finally, by establishing the relationship between the Mohr-Coulomb expression and the ultimate tensile stress, we obtained the cohesive force (c) and further analyzed the degradation mechanism of the recycled asphalt mixture under the loading rate and chloride salt. However, the effect of RAP content on c is influenced by various factors, which should be considered comprehensively. These research results enrich the mechanism analysis of the low-temperature cracking performance of plant-mixed heated asphalt mixture and provide theoretical guidance for enhancing the low-temperature cracking resistance design of asphalt pavement.

Performance Evaluation of Reclaimed Asphalt Pavement (RAP) Incorporated Concrete for Rigid Pavements

Abstract: The production of Reclaimed Asphalt Pavement (RAP) has seen a recent increase, and Pakistan's road network spans almost 100,000 kilometers, with almost 30% of RAP able to be produced from it. This study aimed to explore the use of RAP as an aggregate in rigid pavements. Virgin coarse aggregate (VCA) was partially or completely replaced with RAP at ratios of 0, 25, 50, 75, and 100%. A mix design was carried out to achieve 4000psi, and fresh concrete specimens were cast and tested for slump, temperature, and unit weight. After 28 days of curing, some of the hardened concrete specimens were tested for compression and tensile strength using a Universal Testing Machine (UTM) machine, while flexural tests were conducted on beams. The modulus of adaptability was calculated using UCAM programming with the help of a data logger. The results indicated that compressive, flexural, and splitting tensile strength reduced with an increase in RAP content. However, the modulus of elasticity plots shows that while the stiffness decreased with an increase in RAP content, ductility shows a slight improvement. Based on the findings, replacing up to 25% of VCA with RAP was considered the best permissible replacement in rigid pavement, offering maximum performance. Additionally, a cost analysis of RAP showed a 71% cost saving in VCA and 3% overall section cost saving by replacing just 25% of RAP.

Evaluation of High-Temperature and Antireflection Cracking Performance of Warm Mixed Recycled Asphalt Mixture

To study the influence of temperature and reclaimed asphalt pavement (RAP) content (0%, 30%, 50%, and 70%) on the high-temperature performance and anti-reflection cracking performance of warm-mix recycled asphalt mixture, triaxial repeated creep tests and overlay tests (OT) based on digital image correlation technology (DIC) were used to analyze the high temperature and anti-reflection cracking performance of recycled asphalt mixtures. Based on the improved Burgers model, a permanent deformation (PD) model was established to evaluate the high-temperature performance of recycled asphalt mixtures. The anti-reflection cracking performance of recycled asphalt was quantitatively analyzed from macro and meso perspectives by using a macro index (load loss rate) and a meso index (vertical strain density DE). In addition, a reflection cracking damage model was developed by cumulative load loss rate relative change rate, and the fractal characteristics of reflection cracks were studied according to the fractal theory. The results show that with an increase in RAP content, the anti-deformation ability of a recycled asphalt mixture is enhanced, and the anti-reflection cracking performance becomes worse. However, with an increase in temperature, the anti-deformation ability of recycled asphalt mixture is weakened, and the anti-reflection cracking performance is enhanced. A PD mechanical model can well describe the high-temperature deformation resistance of recycled asphalt mixtures. The established reflection cracking damage model has high fitting accuracy and accurately describes the reflection cracking damage evolution process of recycled asphalt mixture. In addition, the analysis of the fractal characteristics of reflection cracks shows that the reflection cracks of a recycled asphalt mixture have fractal characteristics of statistical significance. DIC technology can be used to evaluate the anti-reflection cracking performance of recycled asphalt mixtures qualitatively and quantitatively from the mesoscopic perspective, which makes up for the current deficiency in macroscopic evaluation.

Mechanical properties evaluation of asphalt mixtures with variable contents of reclaimed asphalt pavement (RAP)

This research paper aims to evaluate the performance of hot asphalt mixes containing reclaimed asphalt pavement (RAP) at different percentages. The usage of RAP as a recycled construction material has become a common practice in many countries nowadays. To achieve this objective, experimental tests were conducted on a total of 15 asphalt mixtures prepared with five different contents of asphalt cement, including 3.5, 4, 4.5, 5, and 5.5%. Three Marshall mixes were made for each asphalt content. Following the ASTM standards, Marshall stability and flow tests were performed to determine the optimum asphalt content of each mix tested (i.e., control, 25% RAP, 50% RAP, and 75% RAP mixes, respectively). The results showed an improvement in the stability and flow values with the increase in RAP content. Maximum stability of 15.11 kN was obtained with a 75% RAP mix at 4% asphalt cement content. Notably, as the asphalt content increases, lower air voids values and vice versa, higher voids filled with asphalt were observed for the four tested mixes.

Rutting and moisture-induced damage potential of foamed warm mix asphalt (WMA) containing RAP

Despite significant economic and environmental benefits, performance of warm mix asphalt (WMA) containing reclaimed asphalt pavement (RAP) remains a matter of concern. Among the current WMA technologies, the plant foaming technique (called “foamed WMA” in this study) has gained the most attention, since it eliminates the need for chemical additives. In the present study, the laboratory performance, namely rutting and moisture-induced damage potential of foamed WMA containing RAP were evaluated and compared with those of similar hot mix asphalt (HMA) containing identical amount of RAP. Dynamic modulus, Hamburg wheel tracking (HWT) and flow number tests were performed to assess the rutting resistance of the mixes. Also, stripping inflection point from HWT tests and tensile strength ratio after AASHTO T 283 and moisture induced sensitivity test (MIST) conditioning were used to evaluate the moisture-induced damage of asphalt mixes. It was found that MIST conditioning effectively simulates the moisture-induced damage and can capture the propensity of asphalt mixes to moisture damage more distinctly compared to AASHTO T 283 method due to application of cyclic loadings. The foamed WMA was found to exhibit higher rutting and moisture-induced damage potential due to lower mixing and compaction temperatures compared to HMA. However, the increase in RAP content was found to reduce rutting and moisture-induced damage potential for WMA. Therefore, the lower stiffness of foamed WMA may be compensated with the addition of stiffer binder from RAP.

Pore Structure Characteristics of RAP-Inclusive Cement Mortar and Cement Concrete Using Mercury Intrusion Porosimetry Technique

Abstract The pore structure characteristics of cement mortar and concrete incorporating reclaimed asphalt pavement (RAP) fine aggregates as part replacements of natural fine aggregates (NAs) were studied using mercury intrusion porosimetry (MIP) technique. NAs were replaced by RAP at 25, 50, 75, and 100 % by volume of total fine aggregates. Mineral admixtures, namely silica fume and activated sugarcane bagasse ash, were incorporated as part replacements of cement as well. MIP technique could identify the mesopores and macropores in the cementitious mixture. Porosity increases with an increase in RAP content in cementitious mixture, owing to larger and porous interfacial transition zone. Total intrusion pore volume increases with an increase in RAP content and is greater than the control mix irrespective of RAP content and mineral admixture. Mesopores and macropores follow a similar trend as total intrusion pore volume, suggesting finer and larger pores in RAP-inclusive cementitious mixtures. Threshold diameters were observed to initially decrease until 50 % RAP content and to increase thereafter for RAP-inclusive cement mortar, suggesting easy penetration of chemical species for higher RAP content mixes. From pore classification studies, entrained air, large capillaries, medium capillaries, and small capillaries were also analyzed. Large capillaries follow a similar trend to threshold diameter, in which the former affects the transport processes in cementitious mixture. RAP-inclusive cementitious mixtures have the ability to resist freeze as well as thaw and salt decay; this is concluded indirectly from pore structure studies. The pore-mass fractal dimension has the ability to describe the pore-solid structure, whereas the pore-surface fractal dimension failed to do so for RAP-inclusive cementitious mixtures.

Effect of freeze-thaw cycles on the resilient moduli and permanent deformation of RAP/natural aggregate unbound base mixtures

Abstract This paper presents an experimental study to evaluate the effect of freeze-thaw cycles on the resilient modulus and permanent deformation of reclaimed asphalt pavement (RAP)/natural aggregate mixtures for the construction of unbound base layers. A repeated load triaxial test was carried out on RAP and crushed limestone mixtures with varying RAP content (0%, 20%, 35%, and 50% of dry mass), on both standard samples and samples exposed to fourteen freeze-thaw cycles. Freeze-thaw conditioning resulted in a decrease of resilient modulus values and an increase of permanent deformation. This trend was most pronounced on the mixture with 0% RAP. Mixtures with 35% RAP exhibited stable resilient behavior and lowest change in accumulation of permanent deformation after freeze-thaw conditioning. With an increase in RAP content, the sensitivity of the mixtures to freeze-thaw cycling in regards to resilient and permanent deformation behavior is reduced, but only up to a certain RAP content.

Effect of reclaimed asphalt pavement on performance of rubberised asphalt mixtures

The utilisation of crumb rubber (CR) and reclaimed asphalt pavement (RAP) has proven to be an economical, environmentally sound and effective way of increasing the performance of asphalt mixtures. The objective of this study was to evaluate the use of CR in high RAP content asphalt mixtures. The RAP content was 0%, 20%, 40% or 60% and CR (0%, 10% and 20% by weight of bitumen) was blended with the unmodified binder using a wet process. The performance characteristics of these modified asphalt mixtures were investigated through a series of laboratory tests such as the indirect tensile strength, moisture susceptibility, resilient modulus, rutting resistance and fatigue behaviour. The results of the experiments indicated that the fatigue life of the mixtures decreased with an increase in RAP content. The addition of CR led to an increase in the fatigue life of the mixtures. Also, as the percentage of RAP in the mixtures was increased, the rut resistance of the CR-modified mixtures substantially increased. Statistical analysis showed that the addition of RAP and CR had a significant effect on reducing the permanent deformation of the mixtures. According to the results, 10% CR and 40% RAP could be used without a significant reduction in the performance of the mixture.

Strength and permeation characteristics of cement mortar with Reclaimed Asphalt Pavement Aggregates

In order to assess the effect of fine fraction of Reclaimed Asphalt Pavement (RAP) aggregates as an alternative to natural fine aggregates (NA), cement mortar samples were prepared with 25%, 50%, 75% and 100% replacement of natural aggregates. The influence of grading of fine aggregates was also studied. Even though the compressive strength, flexural strength and splitting tensile strength were decreasing with increase in RAP content, the mortar mixes possessed minimum strength requirement providing the potential of fine RAP aggregate as an alternative. The trend of sorptivity characteristics of RAP cement mortar were in contradiction to the porosity nature of the same which suggests that the conventional methodology to determine the former will not cater for concrete or mortar mixes with RAP aggregates.

Comparison of moisture and fracture damage resistance of hot and warm asphalt mixes containing reclaimed pavement materials

The present study evaluates moisture and fracture resistance performance of Hot Mix Asphalt (HMA) and Warm Mix Asphalt (WMA) containing different percentages of Reclaimed Asphalt Pavement (RAP) materials. The HMA and WMA mixes with different percentages of RAP (i.e., 0%, 10%, 20%, 30% and 40%) were designed using Marshall mix design. The warm mixes were prepared by adding 2% wax. Overall, 10 mixes (five HMA-RAP mixes, and five WMA-RAP mixes) were prepared in the laboratory. The moisture damage potential of different mixes was determined using Tensile Strength Ratio (TSR) test. Furthermore, fracture resistance of HMA-RAP and WMA-RAP mixes were evaluated using a Semi Circular Bending (SCB) test based on fracture mechanics principles. The analyses of results showed that addition of RAP increased TSR value of the mix, indicating that RAP may help in enhancing moisture damage potential of a mix. The TSR value of HMA-RAP mixes was found to be higher compared to WMA-RAP mixes for all RAP percentages, showing that WMA mixes are more prone to moisture damage compared to HMA mixes. The fracture resistance was found to be increasing with increase in RAP content in this research work. However, it is to be noted that improvement in fracture property with increase in RAP content may not be theoretically correct due to increase in stiffness characteristics. Such trend in the present research work may be attributed to absence of relaxation time in SCB testing protocol, unaccountability of post peak behaviour in the present research work and variability in material properties. Therefore, further investigation is needed in this direction to develop more understanding for such change before making further recommendation. Furthermore, the fracture resistance of HMA-RAP mixes was found to be better compared to WMA-RAP mixes. Overall moisture and fracture resistance performance of HMA-RAP mixes were observed to be better compared to WMA-RAP mixes. Moreover, Literature showed that asphaltic mixture containing RAP and WMA additive is highly influenced by amount of RAP and WMA added to HMA, type of WMA additive, source and nature of collected RAP etc. Therefore considering finding of current research work and reported literature in this area, inclusion of RAP in WMA mixes should be evaluated carefully before making further recommendation.

Cracking Resistance Characterization of Asphalt Concrete Containing Reclaimed Asphalt Pavement at Intermediate Temperatures

The cracking resistance of asphalt concrete (AC) that contains reclaimed asphalt pavement (RAP) was evaluated in this study with a fracture energy approach. Monotonic and cyclic semicircular bending (SCB) tests were performed with the digital image correlation to correlate crack length with fracture energy. Five types of AC that contained various RAP content (0%, 15%, 30%, 40%, 50%) were evaluated at two intermediate temperatures (15°C and 25°C). On the basis of the relationship between fracture energy and crack extension length, several performance indicators for cracking were proposed: fracture energy and crack initiation energy in monotonic and cyclic SCB tests, an energy cumulative rate in monotonic SCB tests, a fatigue accumulation index (FAI), a fracture energy index, and the slope of the crack steady propagation stage (SOCSP) in cyclic SCB tests. The effects of the RAP content on these indicators were investigated. It was observed from the test results that RAP reduced the fracture energy and crack initiation energy in the monotonic and the cyclic SCB tests. RAP led to a lower energy cumulative rate than an AC mix without RAP in the monotonic SCB tests. Similarly, the FAI and SOCSP values were found to decrease with an increase in RAP content in the cyclic SCB tests. These results indicated that, in general, the addition of RAP reduced the cracking resistance at intermediate temperatures.

Fatigue life and endurance limit prediction of asphalt mixtures using energy-based failure criterion

Fatigue cracking is one of the major types of distress in asphalt mixtures and is caused by the accumulation of damage in pavement sections under repeated load applications. The fatigue endurance limit (EL) concept assumes a specific strain level, below which the damage in hot mix asphalt (HMA) is not cumulative. In other words, if the asphalt layer depth is controlled in a way that keeps the critical HMA flexural strain level below the EL, the fatigue life of the mixture can be extended significantly. This paper uses two common failure criteria, the traditional beam fatigue criterion and the simplified viscoelastic continuum damage model energy-based failure criterion (the so-called GR method), to evaluate the effect of different parameters, such as reclaimed asphalt pavement (RAP) content, binder content, binder modification and warm mix asphalt (WMA) additives, on the EL value. In addition, both failure criteria are employed to investigate the impacts of these parameters in terms of the fatigue life of the study mixtures. According to the findings, unlike an increase in RAP content, which has a negative effect on the mixtures’ fatigue resistance, a higher binder content and/or binder modification can significantly increase the EL value and extend the fatigue life as was proved before by other researchers, whereas WMA additives do not significantly affect the mixtures’ fatigue behaviour. A comparison of the model simulation results with the field observations indicates that the GR method predicts the field performance more accurately than the traditional method.

Evaluation of moisture susceptibility of asphalt mixes containing RAP and different types of aggregates and asphalt binders using the surface free energy method

The surface free energy (SFE) measurement of asphalt binder and aggregate is considered a reliable mechanistic framework for evaluating the moisture-induced damage potential of asphalt mixes. In the present study, the SFE method was used to evaluate the effects of asphalt binder type, Reclaimed Asphalt Pavement (RAP) and its amount, and aggregate type on the moisture-induced damage potential of asphalt mixes. The SFE components (non-polar, acid and base) of a PG 64-22 and a PG 76-28 (polymer-modified) asphalt binders, blended with different amounts of RAP binder (0%, 10%, 25% and 40%) were measured in the laboratory using a Dynamic Contact Angle (DCA) analyzer. Also, the SFE components of six types of aggregates, namely limestone, rhyolite, sandstone, granite, gravel, and basalt were used in this study. The SFE components of limestone and rhyolite aggregates were measured using a Universal Sorption Device (USD), while those of the sandstone, granite, gravel, and basalt aggregates were obtained from the literature. The energy ratio parameters estimated based on the spreading coefficient, the work of adhesion, and the work of debonding were used to assess the moisture-induced damage potential of different combinations of asphalt binders and different RAP binder contents and aggregates. The SFE test results indicated that the acid SFE component of PG 64-22 and PG 76-28 asphalt binders increase with the addition of RAP binder, while the base SFE component remains almost unchanged. Also, the wettability and the work of adhesion of both PG 64-22 and PG 76-28 asphalt binders over different types of aggregates increased with an increase in RAP content (by 25% and more). Based on the energy ratio parameters, it was found that the resistance to moisture-induced damage increased with an increase in RAP content for both PG 64-22 and PG 76-28 asphalt binders and all types of aggregates, specifically when higher RAP contents were used. Moreover, it was found that the higher the total SFE of the aggregates, the lower the energy ratio parameter values. Therefore, a high total SFE component of aggregate may result in a high moisture-induced damage potential of the mix. The results presented herein are expected to be helpful in mechanistically assessing the moisture-induced damage potential of asphalt mixes, produced with polymer-modified and non-polymer-modified asphalt binders, containing RAP.

Laboratory Investigation of Cement-Treated Reclaimed Asphalt Pavement Material

Cold in-place recycling is considered as a pavement rehabilitation technique that is more environmentally friendly than the common practice of simply constructing a new hot-mix asphalt (HMA) overlay on the existing wearing surface. This paper describes a laboratory experimental study for the formulation and mechanical characterization of cement-treated reclaimed asphalt pavement (RAP) material to be used as a base layer during the rehabilitation of pavements. RAP content was varied between 0 and 100% in order to study the effects of this parameter on the mechanical properties. Portland cement content was kept constant at 6% by weight of dry constituents. Results have shown that an increase in RAP content results in a decrease in compressive strength, flexural strength, indirect tensile strength, and elastic modulus. However, for any RAP content of 60% or less, acceptable mechanical properties for a pavement base layer were achieved. Unrestrained shrinkage testing showed statistically insignificant change in shrinkage strain with RAP content.

Hybrid life cycle assessment for asphalt mixtures with high RAP content

With the pavement industry adopting sustainable practices to align itself with the global notion of habitable environments, there has been growing use of life-cycle assessment (LCA). A hybrid LCA was used to analyze the environmental footprint of using a reclaimed asphalt pavement (RAP) content in asphalt binder mixtures. The analysis took into consideration the material, construction, and maintenance and rehabilitation phases of the pavement life cycle. The results showed significant reductions in energy consumption and greenhouse gas (GHG) emissions with an increase in RAP content. The contribution of the construction phase to the GHGs and energy consumption throughout pavement life cycle is minimal. Feedstock energy, though not consequential when comparing asphalt mixtures only, has a significant impact on total energy. Based on LCA analysis performed for various performance scenarios, breakeven performance levels were identified for mixtures with RAP. The study highlighted the importance of achieving equivalent field performance for mixtures with RAP and virgin mixtures.

STRENGTH ASSESSMENT OF CEMENT TREATED SOIL-RECLAIMED ASPHALT PAVEMENT (RAP) MIXTURE

The article attempts to present the influence of reclaimed asphalt pavement (RAP) content on the compaction behavior and unconfined compressive strength of cement treated soil-RAP mixture. The laboratory compaction and unconfined compression tests on cement treated soil-RAP mixture were carried out with various RAP and cement contents. The porosity was adopted as a state parameter for assessing the strength of the mixed materials. The results show that with an increase in RAP content, the OMC tends to decrease, up to the optimum of soil/RAP ratio of 50/50. The asphalt fixation point is designated as a transitional point where less change in strength turns to a larger change. An asphalt content of 3.5% (50/50 soil/RAP ratio) is found to be the asphalt fixation point. The strengths, where the asphalt content is lower than the asphalt fixation point, can be predicted by the proposed generalized form of strength. This proposed equation can assess the laboratory strength of cement treated soil-RAP mixture under various mixed proportions, cement contents, water contents, and curing times.

Asphalt Pavements with High Reclaimed Asphalt Pavement Content

Today's sustainability-driven systems require a product or process to be environmentally beneficial as well as cost-effective. This study used life-cycle cost analysis (LCCA) and life-cycle assessment (LCA) to consider the economic and environmental feasibility of using a high content of reclaimed asphalt pavement (RAP) in asphalt mixtures. The LCCA conducted in the study incorporated agency cost as well as the costs incurred by the user in the construction work zone. Initial construction as well as future maintenance and rehabilitation activities were considered in the analysis. The hybrid LCA took into account the material, construction, and maintenance and rehabilitation phases of the pavement life cycle. The results showed savings in terms of costs and energy use and reduction in greenhouse gas emissions with an increase in RAP content. On the basis of the LCCA and LCA performed under various performance scenarios, break-even performance levels were identified for mixtures with up to 50% RAP content. Break-even performance levels underscored the importance of achieving field performance for recycled mixtures equivalent to that for control virgin mixtures.

LABORATORY STUDIES OF DENSE BITUMINOUS MIXES-II WITH RECLAIMED ASPHALT MATERIALS

The issue of growing demand on our nation’s roadway s over that past couple of decades, decreasing budg etary funds, and the need to provide a safe, efficient, and cost effective roadw ay system has led to a dramatic increase in the nee d to rehabilitate our existing pavements and the issue of building sustainable roa d infrastructure in India. With these emergency of the mentioned needs and this are today’s burning issue and has become the purpos e of the study. In the present study, the samples of existing bitum inous layer materials were collected from NH-48(Dev ahalli to Hassan) site.The mixtures were designed by Marshall Method as per As phalt institute (MS-II) at 20% and 30% Reclaimed As phalt Pavement (RAP). RAP material was blended with virgin aggregate such that all specimens tested for the, Dense Bituminou s Macadam-II (DBM-II) gradation as per Ministry of Roads, Transport, and Highways (MoRT&H) and cost analysis were carried ou t to know the economics. Laboratory results and analysis showed the use of rmaterials showed significant variability in Marshall Stability, and the variability increased with the increase in RAP cont ent. The saving can be realized from utilization of recycled materials as per the methodology, the reduction in the total cost is 19% , 30%, comparing with the virgin mixes.