Now days, reclaimed asphalt pavements are used in the production of asphalt mixtures. The use of this material has too many economic and environmental benefits. Beside, warm mix additives are materials that they reduce production temperature of asphalt mixtures and improve their workability in the constructed pavements. There is always a question that “, what are the effects of reclaimed asphalt pavement and warm additive on the mix design parameters of asphalt mixtures? ”,In this research, the simultaneous effects of reclaimed asphalt pavement and a warm additive named Sasobit on the technical properties of asphalt mixtures were evaluated. For this purpose, an experimental plan was designed based on the response surface method for reclaimed asphalt pavement (from 0 to 50%), asphalt binder content (from 4 to 6%) and Sasobit content (from 0 to 3%). Then, the volumetric and strength properties of these mixtures were determined and compared with the Iranian pavement code criteria. Obtained laboratory results showed that an optimum point for fabrication of asphalt mixtures containing reclaimed asphalt pavement is a mixture with 4. 6% asphalt binder, 12% reclaimed asphalt pavement and 3% Sasobit additive. Also, increasing the amount of the Sasobit showed that it increases the value of the Marshal strength, asphalt unit weight of mixtures and it reduces its air voids.

In this research, the effect of waste polybutadiene rubber (PBR) has been investigated in the performance evaluation of asphalt mixtures containing RAP. Different percentages of RAP, including 20, 30, and 50%, were selected to prepare the asphalt mixture. To prepare polymer-modified bitumen, bitumen 60/70 was mixed with 5% by weight of waste PBR polymer and then added to asphalt mixtures containing different percentages of RAP. In this study, four-point bending beam, modified Lottman and Hamburg Wheel-Track tests were performed to evaluate the fatigue behavior,   moisture susceptibility, and the rutting resistance of asphalt mixtures containing RAP, respectively. The results showed that the presence of utilized waste polymer significantly improved the fatigue behavior of asphalt mixtures containing 20 and 30% RAP compared to the control mixture. Also, the use of this polymer can be used in asphalt mixtures with a RAP percentage of less than 50% (about 40%) without any concern about reducing the fatigue resistance of asphalt. Furthermore, the results showed that by using waste PBR in asphalt mixtures containing RAP, the resistance of the mixtures against moisture susceptibility has increased significantly compared to the control mixture. The results of the Hamburg Wheel-track test also showed that the combination of RAP materials and used waste polymer could reduce the rut depth by 70% in comparison with the control mixture.

Half warm mix asphalt (H-WMA) is one of the alternatives to conventional asphalt due to its special production conditions.  Half warm mix asphalt (H-WMA) manufactured with high proportions of reclaimed asphalt pavement (RAP). Half warm mix asphalt (H-WMA) are produced and compacted at the temperature range of 60-100 ° C, which requires less temperature for production process of hot mix asphalt (HMA) for example cold mix asphalt (CMA) manufactured at a temperature lower than 60 ° C; (ii) half warm mix asphalt (H-WMA) manufactured at less than 100 ° C, normally at 60-100 ° C; (iii) warm mix asphalt (WMA) manufactured at temperatures of 100-140 ° C. The aim of this study is to investigate the effects of high percentages of reclaimed asphalt pavement (RAP) on the volumetric and mechanical properties of Half warm mix asphalt (H-WMA) mixtures. In this research, bitumen emulsion (CSS-1) and conventional bitumen 60/70 were used. The siliceous aggregates were obtained from a mine near Tehran and reclaimed asphalt pavement (RAP) were obtained from an asphalt plant and its granulation before and after extraction was done according to report number 234.  Generally speaking, in H-WMA, aggregates are heated to temperatures of 100-110 ° C and then mixed with emulsion, which has previously been heated to 60-80 ° C and RAP are heated to 90-100 ° C. To determine the most suitable mixing time in the tests, the coating was visually analyzed after mixing times of 1 and 2 min and the mixing temperature was 95-85 ° C. Thus, a laboratory analysis was carried out in which the behavior of half warm mix asphalt (H-WMA) manufactured with 100%, 70% and 0% reclaimed asphalt pavement (RAP) was compared with that of a control mix, Hot mix asphalt (HMA). Optimum bitumen content for hot asphalt mixture (HMA) and optimum bitumen emulsion content for half warm mix asphalt (H-WMA) were calculated. Then indirect tensile tests (IDT) (at 25° C), moisture damage (TSR) and Semi-Circular Bending (SCB) Tests (at 25° C and -20° C) were performed on half warm mix asphalt (H-WMA) and hot mix asphalt (HWA). indirect tensile tests (IDT) yielded acceptable results, the IDT resistance increased with increasing the reclaimed asphalt pavement (RAP) content. Following this, the moisture damage (TSR) of half warm mix asphalt (H-WMA) improves by increasing the reclaimed asphalt pavement (RAP) content, which can be due to the complete covering of the surface of the aggregates with aged bitumen and the high adhesion force between the aged bitumen and the aggregates and the lack of moisture penetration into the aggregates. emulsified bitumen exhibited proper volumetric (e.g., air voids and density) and mechanical behavior in terms of moisture damage and IDT. On the other hand, the results of SCB tests at medium and low temperatures showed that by increasing the RAP content the samples become brittle, which means that resistance to crack propagation reduced, and it may be the reason for fracture energy reduction. These findings encourage greater confidence in promoting the use of these sustainable asphalt mixes for their use in road pavements or urban streets.

Asphalt recycling not only is one of the effective approaches to increase the efficiency of the existing budget and capital which is used to protect and improve the road network but also leads to conserve natural resources and save expenses. However, the process of producing Hot Mix Asphalt (HMA) using Reclaimed Asphalt Pavement (RAP) leads to hardening of bitumen and quite a bit of environmental pollution which is derived by emission of toxic gases. Besides, reducing environmental pollution as well as saving energy, reducing the temperature in Warm Mix Asphalt (WMA) technology decreases aging and stiffness of bitumen caused by oxidation. Furthermore, by utilizing WMA technology, better working conditions regarding lower heat rate and emission of poisonous materials are provided. To reduce the costs and the environmental pollution caused by asphalt production as well as improve the performance of asphalt, this research evaluated two approaches, including WMA with Kaowax additive and RAP techniques. The additive of Para-fiber with different values was also used to improve the functional properties of the asphalt. Resilient modulus, dynamic creep, and fatigue tests were performed to compare and evaluate the performance of asphalt mixtures. Given the results, in addition to improvement of the resistance against permanent deformation, utilizing RAP causes an increase in resilient modulus of the mixture, the reason lies in increasing the stiffness of asphalt mixture because of adding RAP. According to the results of fatigue tests, by adding RAP, the fatigue life of the mixture is significantly decreased. On the contrary, by adding Para-fiber, the fatigue life is considerably improved. It seems that tensile resistance and high flexibility of Para-fiber can be considered as the reason for improving the fatigue function of asphalt mixture. Thus, the costs and environmental pollutions can be reduced,meanwhile, an asphalt with good function can be produced.

Today، the greenhouse gas emission from industry and transport is the most important factors in the destruction of ecosystems and natural resources. One of the main sources of pollution is industries related to construction، maintenance and improvement of transport infrastructure. The production of cleaner asphalt needs to reduction of temperature in the asphalt mixture، without a reduction in mechanical performance levels. The reuse of Reclaimed Asphalt Pavement (RAP) in the production of new asphalt preserves natural resources and reduces environmental pollution. In this study، the use of RAP in producing hot and warm mix asphalt mixtures and effects of two additives (Sasobit and Zycotherm) was evaluated. The amount of RAP in the mixture was 50، and 75% and percentage of Sasobit and Zycotherm were 2 and 0. 1% respectively. The addition of Sasobit improves the compressibility and strength of asphalt mixture effectively، so the sample containing 75% of RAP had better compressibility and strength، but Zycotherm caused improvement of compressibility and considerable decrease in air void range and increase stability of mixtures containing 75% RAP. Generally، partial strength values of WMA with 75% RAP is not very different from HMA. Finally، TSR test results have increased along with the increase in the percentage of sub-asphalt materials ratio which shows low sensitivity to moisture in the recycled mix.

The use of Reclaimed Asphalt Pavement (RAP) helps us save our natural resources and money. Of the different types of asphalt pavements that can be built, HMA pavements are considered the best in the terms of strength and durability. But the production temperature limits the amount of RAP used in the new mixture because this production`s high temperature requirement causes the deterioration of the aged binder of RAP and increases greemhouse gas emission. In the recent years there has been much focus on Warm Mix Asphalt (WMA) technology, because the aim of this approach is to reduce the production temperature by using additives which increase the workability of the binder at a lower temperature. The use of WMA additives helps us reduce the temperature while preserving the desired workability, thus enables HMA to contain higher percentages of RAP. The purpose of this experimental study was to evaluate the effect of production temperature reduction by using WMA additives on the performance properties of asphalt mixture containing 100% RAP. To reach this goal, five mixes were prepared and tested: a control mix (100% RAP-mixing temperature 150° C), three mixes with Sasobit, Rheofalt and without additives (mixing temperature of 130° C), and one virgin mix with extracted aggregate (mixing temperature of 160° C). The performance properties of the mixtures were evaluated based on indirect tensile strength, resilient module, four point beam fatigue test, and dynamic creep test etc. The results showed that the mixtures with WMA additives had better performance according to their moisture susceptibility and rutting potential, but the control mix had better performance in fatigue and low temperature cracking.

The non-renewability of natural materials and the prevention of environmental degradation for the production of stone materials, has increased the tendency to use waste materials in asphalt mixtures in recent decades. Several research studies were conducted to assess WMA mixtures' mechanical properties containing Reclaimed Asphalt Pavement (RAP), Electric Arc Furnace Slag (EAFS), and waste plastic (WP) separately. However, very scarce studies assessed the influence of the simultaneous presence of RAP, EAFS, and waste plastic on the mechanical properties and moisture susceptibility of WMA mixtures. This research investigates the effects of simultaneous recycling of RAP, EAFS, and waste plastic into the WMA mixtures to remove these barriers. Mechanical properties of WMA mixtures containing different percentages of RAP (0%, 35%, and 55%, fine aggregate replacement), EAFS (0%, 20%, and 40%, coarse aggregate replacement), and waste plastic (0%, and 10% bitumen weight) were evaluated using compressive strength, resilient modulus, static creep, Marshall quotient, and moisture susceptibility tests. Sasobit uses 1.5% of the total asphalt mass to prepared WMA mixtures. The results of this study were shown to improve the moisture sensitivity, rutting resistance, and resilient modulus by increasing the percentage of RAP and also reduce the resistance to moisture sensitivity and improve the compressive strength of mixtures by increasing the percentage of EAFS and decreasing the compressive strength and resilient modulus by increasing waste plastic. The simultaneous use of EAFS, RAP, and waste plastic seems to produce an environmentally-friendly mixture with minimum mechanical properties.

The demolishing of roads for repair and reconstruction produces an ample amount of Recycled Asphalt Pavement (RAP) which, if not utilized, may cause depletion of aggregate sources and pollution. The use of RAP in the plain cement concrete (PCC) is sustainable use of road waste material. However, the potential of incorporating RAP to replace natural aggregate needs to evaluate. This research targets the evaluation of mechanical properties of PCC made with extracted RAP materials through laboratory experiments and to achieve the optimized replacement of natural aggregate for rigid pavement composite design. The Virgin Coarse Aggregate (VCA) in PCC was replaced with RAP at 0:25:100 percent by weight. Results show that incorporating RAP in PCC causes a gradual decrease in mechanical properties. However, the decrease in compressive strength is more (57%) than the flexural and splitting tensile strength. RAP up to 25% was found as an optimum allowable replacement with VCA in the rigid pavement. From the Modulus Of Elasticity (MOE), it was detected that with the incorporation of RAP the ductility of PCC improved slightly.

Pavement quality significantly impacts road safety, serviceability, and maintenance costs. Recently, the use of reclaimed asphalt mixtures has gained attention due to their environmental and economic benefits. However, reheating these materials for reuse can lead to asphalt aging and embrittlement. Consequently, these mixtures are susceptible to low-temperature cracking. Therefore, despite environmental and economic advantages, the unstable performance and potential for increased stiffness and cracking in stone mastic asphalt (SMA) pavements must be carefully managed to ensure durability and service life. This study investigates the fracture properties of SMA mixtures at low temperature (-12 °C) and fatigue behavior at intermediate temperature (25 °C. Different percentages (0%, 15%, and 30%) of reclaimed asphalt pavement (RAP) were used as a substitute for aggregate in SMA mixtures to examine the effects of this substitution on mixture properties. Results indicated that the fracture energy of asphalt mixtures using rejuvenating oil was higher than those without rejuvenating oil. This increase in fracture energy was significantly observed at low temperatures. The flexibility index (FI) analysis showed that adding asphalt shingles without rejuvenating oil reduced flexibility by about 30% compared to the control sample. However, using rejuvenating oil increased the flexibility index by almost twofold compared to the control sample; with an 85% increase in the first mode of loading and a 113% increase in the second mode.

Reclaimed asphalt pavement (RAP) materials, which include aggregate and bitumen, can be used in recycled asphalt mixes and granular base layers. Recycling these materials helps conserve natural resources. It also reduces energy consumption and costs. However, due to the variety of sources as well as insufficient strength, RAP materials without stabilizing additive is not suitable as an alternative to virgin aggregates in granular base layers. Therefore, it is necessary to use a suitable chemical or mechanical stabilization method to use reclaimed asphalt pavement as a base material. In this paper, the properties of RAP materials and aggregates containing different percentages of RAP are reviewed. Then the results of recent studies on the mechanical properties of these materials are presented. The results show that with increasing the percentage of RAP material in mixtures containing RAP, the resilient modulus and the accumulated permanent deformation increase.