Analysis of Carbon Emission during Hot In-Place Recycling Asphalt Pavement Construction

In recent decades, economic development and population growth in the world has led to the expansion of road networks. Therefore the use of optimum methods for repairing and maintenance of these roads is considered as an important value. Today one of the options in this regard, is the use of asphalt recycling technology. The present study which took place in the summer of 2015 in Iran, Lorestan province, is in line with this target with the goal to compare the recycling of asphalt with the common methods as well as the qualitative assessment of each method. In this study which was based on the analysis of asphalt samples from the Khorramabad-boroujerd route and samples from Arak-Qoms hot in-place recycling project, 9 laboratory samples were made using recycled asphalt pavements in accordance with the regulations of hot asphalt recycling of Iran. These samples were made using 80% recycled asphalt pavements which were collected from 3 different locations from lorestan province, as well as 20% raw and new materials. After conducting the quality control tests for asphalt on the 9 samples, one of the 9 samples that had higher technical specifications and was more in accordance with the Arak-Qoms recycling project mix design, was chosen as the optimal sample. The optimum samples test results were analyzed, compared and evaluated with the two projects mentioned above. The results showed that although both methods were in range with the minimum and maximum technical quality specifications, the recycling method had higher quality and technical specifications.

The aged asphalt film transfer between new and old aggregate during hot in-place recycling of asphalt pavement was investigated in this paper. The mechanism of asphalt film transfer between new and old mixture was analyzed by connective mass transfer theory. Based on the theoretical analysis, influence factors for asphalt film transfer during hot in-place recycling were summarized. Then laboratory tests simulating the file hot in-place recycling process were conducted to investigated the asphalt film transfer between new and old aggregate based on different influence factors design. The test results indicated that preheating temperature, mixing time and recycling agent are the key influence factors during hot in-place recycling process. Suggestions to guarantee the quality of hot in-place recycling asphalt mixture were given in this paper.

Strategy for improving the effect of hot in-place recycling of asphalt pavement

Performance evaluation of temperature effect on hot in-place recycling asphalt mixtures

PURPOSES : The objective of this study is to investigate the current state of the practice, examining the steps in the process recommended by various agencies and the Asphalt Recycling and Reclaiming Association (ARRA)-namely mix design, structural design, structural capacity evaluation, and material characterization-in order to better understand the implications of hot in-place recycling (HIR). METHODS : In addition, the current practice of state departments of transportation (DOTs) is here reviewed with the purpose of learning from successful past experiences so as to forestall any difficulties that may emerge under similar circumstances. Also, HIR benefits, including reduced costs, improved construction processes, and environmental friendliness are presented, as well as advantages and disadvantages of HIR application. RESULTS : Most of the United States highway system is now deteriorating so that rehabilitation or reconstruction techniques are required for the most distressed roads, taking into account ways to increase the effectiveness of existing budgets. Several options are available in rehabilitating distressed roads, and the choice among these depends on many factors, including pavement distress condition, funding, and design life. Among these techniques, Hot In-Place Recycling (HIR) has emerged as a cost-effective treatment for deteriorated pavements, and has been proven an effective long-term strategy for pavement rehabilitation.

The substantial accumulation of reclaimed asphalt pavement (RAP) poses a pressing issue in road construction. The hot in-place recycling (HIR) technique has garnered widespread attention due to its high recycling rates of RAP and minimal environmental hazards. This study focuses on the RAP analysis, compaction characteristics, and field evaluation of hot in-place recycled asphalt pavements (HIRAP). Firstly, a novel test method of RAP analysis was proposed to evaluate the suitability of RAP. Subsequently, compaction tests reveal the compaction characteristics of hot in-place recycled asphalt mixture (HIRAM). Finally, the field performance of HIRAP was assessed. The research findings indicate that the RAP analysis method can accurately characterize the status of RAP. Increasing the RAP temperature improves the compaction characteristics of HIRAM. The field tests show that using HIR technology improves the performance of the pavement, in particular with a compaction of 99.7%. This study will establish a theoretical foundation for further promoting the HIR technique.

Study on microstructure of rubberized recycled hot mix asphalt based X-ray CT technology

Comparative eco-efficiency analysis on asphalt pavement rehabilitation alternatives: Hot in-place recycling and milling-and-filling

Heating effects of asphalt pavement during hot in-place recycling using DEM

Heavy traffic loads require the replacement of damaged pavements, so a huge amount of reclaimed asphalt pavement (RAP) material is now available and must be recycled in order to avoid landfill and to achieve both environmental and economic benefits. The most common and profitable solution to reuse RAP is associated with the hot recycling technique, as it allows recovering both solid and binding components of RAP. Several factors influence the performance of hot recycled mix asphalt (HRMA). Among those, this paper focuses on the role played by the origin of the virgin bitumen, i.e. the oil-distillation process, and by the mixing temperature adopted during HRMA production. The objective was to evaluate the rheological properties of mixtures produced using a high amount of RAP (50%), two different rejuvenators, two mixing temperatures (140 °C or 170 °C) and two neat bitumen types derived from different distillation processes (visbreaker and straight-run). The results showed that the addition of RAP led to an increase in the dynamic modulus and a decrease in the phase angle, while the use of rejuvenators partly tended to rebalance these characteristics. The visbreaker bitumen showed a higher sensitivity to short-term aging than the straight-run, determining higher mix stiffness and lower viscous features. The higher mixing temperature also determined an increase in the complex modulus and a reduction in the phase angle as a result of the higher mobilization of the aged bitumen from the RAP.

Influence of mobilized RAP content on the effective binder quality and performance of 100% hot in-place recycled asphalt mixtures

Effects of preheating conditions on performance and workability of hot in-place recycled asphalt mixtures

Rehabilitation of asphalt concrete layers of road pavements using HIR technologies enables effective elimination of surface defects (rutting, cracking, raveling, bleeding (flushing)) including defects caused by the non-conformity of asphalt concrete to the standard specifications. Due to the economical and ecological advantages, HIR technologies belong to the present-day effective alternative methods of rehabilitation of asphalt concrete pavements. In Ukraine, HIR technologies were first applied on intermediate repair works on an area of the international road I-01 “Kyiv-Chernihiv-Novyye Yarylovichi” in the 2013. Now, HIR technologies have been applied on repair works on numerical objects including areas on such state motor roads as I-01, I-06, N-09, R-10, R-67. The presented paper analyzes the results of monitoring of materials and technologies which was aimed on HIR performance investigation supported by State Road Agency of Ukraine (Ukravtodor) throughout 2014-2018. The results of monitoring of HIR technologies including laboratory evaluation of materials and also field testing of the rehabilitated pavements led to the conclusions fitted by the world-wide experience on implementation of HIR technologies. 1. Being applied to the structurally sound pavements, HIR provides effective elimination of surface defects of flexible pavement to a depth of (50-60) mm including defects caused by the non-conformity of asphalt concrete to the standard specifications. However, HIR is not suitable for existing asphalt pavements which have too much variation in asphalt concrete composition and thickness within the project limits. 2. The efficiency of asphalt pavement rehabilitation using HIR technologies largely depends on precise engineering consideration which determines the efficiency of preparatory (repair) works including some special works such as: – correction of cracks in case of cracking that extends below the depth of hot recycling; – re-compaction of an unbound base layer(s) in case of the insufficient compaction causing “alligatored” network-like cracking of asphalt pavement. 3. Proper technical and working conditions of the rehabilitated pavement during the nominal life cycle could be maintained by overlaying the surface treatment using bituminous emulsion materials or by single-pass overlaying a new hot-mixed asphalt concrete layer. Investigations accomplished during the implementation of HIR technologies allow enhance quality of recycled materials and also promote the entire adaptation of HIR technologies to the Ukrainian standards. Keywords: asphalt pavement rehabilitation, hot in-place recycling, recycled asphalt concrete, field testing, road pavement strength measurement, rutting measurement.

In the context of green and low-carbon development, energy saving, and emission reduction, hot recycling technology (RT) has been researched, which is divided into hot central plant RT and hot in-place RT. However, due to the aged asphalt binders, the shortcomings of hot recycled asphalt mixtures have become apparent, as in comparison to new asphalt mixtures, their resistance to cracking was inferior and the cracking resistance deteriorated more rapidly. Therefore, it was very necessary to focus on the improvement of crack resistance of hot recycled asphalt mixtures. Basalt fiber has been proved to be able to effectively improve the comprehensive road performance of new asphalt mixtures. Therefore, this paper introduced basalt fiber to hot central plant recycled and hot in-place recycled asphalt mixtures, in order to improve the crack resistance of asphalt as a new type of fiber stabilizer. Firstly, six types of SMA-13 fiber asphalt mixtures were designed and prepared, i.e., hot mixtures with basalt fiber or lignin fiber, hot central plant recycled mixtures with basalt fiber or lignin fiber, and hot in-place recycled mixtures with basalt fiber or lignin fiber. Secondly, the trabecular bending test, low-temperature creep test, semi-circular bending test, and IDEAL-CT were used to comparatively study the changing patterns of low and intermediate temperature cracking resistance of hot recycled mixtures with conventional lignin fibers or basalt fibers. Finally, Pearson's correlation coefficient was used to analyze the correlation of the different cracking resistance indicators. The results show that the low and intermediate temperature cracking resistance of hot central plant recycled mixtures increased by 45.6% (dissipative energy ratio, Wd/Ws) and 74.8% (flexibility index, FI), respectively. And the corresponding cracking resistance of hot in-place recycled mixture increased by 105.4% (Wd/Ws) and 55.7% (FI). The trabecular bending test was more suitable for testing the low-temperature cracking resistance of hot recycled asphalt mixtures, while the IDEAL-CT was more suitable for testing the intermediate-temperature cracking resistance. The results can provide useful references for the utilization of basalt fiber in the hot recycling of SMA-13 asphalt mixtures.

In this paper, the influence of RAP content on pavement performance of hot plant recycling asphalt mixture is experimentally studied. The pavement performances contain high temperature stability, low temperature stability, water stability and fatigue resistance. Recovered asphalt was firstly extracted from RAP, and the properties of recovered asphalt was then tested and compared to normal 70# pavement asphalt. The gradation of recovered aggregate and new aggregate was then tested, and the mine material mixture gradation was determined. Marshall Test was adopted to determine the optimal asphalt content. The pavement performances show that the dynamic stability increases with RAP content increasing. The blending strain and fatigue life decreases while the stiffness modulus increases with the RAP content increasing. However, the residual stability and TSR show no obviously change with RAP content increasing.