Laboratory Performance Evaluation of Warm-Mix Asphalt Containing High Percentages of Reclaimed Asphalt Pavement (original) (raw)
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Journal of Cleaner Production, 2018
Warm-mix asphalt (WMA) technology and rejuvenator are widely used nowadays because of numerous environmental and economic benefits. This study evaluated the effects of warm-mix asphalt (WMA) technology and rejuvenator on the rutting resistance, cracking resistance, and moisture susceptibility of three types of asphalt mixtures. The three types of asphalt mixtures were (a) an asphalt mixture with 50% reclaimed asphalt pavement (RAP), (b) an asphalt mixture with 50% RAP and rejuvenator, (c) a warm mixture containing 50% RAP. The WMA mixtures were plant-produced with a foaming technology commonly used in the United States. Laboratory performance tests included the Superpave indirect tension (IDT) test, tensile strength ratio (TSR) test, asphalt pavement analyzer (APA) rutting test, Hamburg Wheel-tracking test (HWT) and semicircular bending (SCB) test. Research shows that the rejuvenator could improve the moisture and cracking resistance, but increase the rutting potentials and decrease the indirect tensile strength. In contrast with the mixture with 50% RAP, WMA technology showed promising results in the rutting resistance and moisture susceptibility. Besides, adoption of WMA technology was more cost-effective.
To evaluate the performance of Warm Mixture Asphalt (WMA) with varying amounts of recycled asphalt pavement (RAP) in comparison with Hot Mix Asphalt (HMA), comprehensive laboratory and field evaluations were conducted. Mix designs were performed for both WMA with a LEADCAP additive and HMA with large amounts of fractionated RAP materials. Hamburg Wheel Tracking (HWT) test was performed to evaluate the rutting and moisture susceptibility of both HMA and WMA laboratory mixtures. HMA mixtures with up to 50% RAP materials by binder replacement exhibited a better performance than WMA mixtures. However, when RAP materials were increased to 75% both WMA and HMA mixtures showed a superior performance. When a specially designed LEADCAP additive for a mixture with a high RAP content called “RAPCAP” was used, the performance was significantly improved. The existing Asphalt Bond Strength (ABS) test (AASHTO TP91-11) was modified to better evaluate the adhesion bond between asphalt binder and aggregate surface. Based on the modified ABS test results, it was found that the asphalt binder type significantly influenced the adhesion bond. To evaluate the performance of WMA mixtures in the field, test sections were constructed in Iowa, Minnesota and Ohio. The test sections were successfully constructed with less compaction effort than HMA and met the required field densities per each DOT’s specification. All HMA and WMA mixtures collected from the test sections passed the HWT and the modified Lottman tests, which indicates high resistance to rutting and moisture damage. The asphalt binders were then extracted and recovered from the field samples then re-graded following AASHTO M320 and AASHTO MP19-10. The recovered asphalt binder grades were found to be higher than the target grades due to the existence of RAP materials in the mixtures except for asphalt binders extracted from WMA mixtures produced using “RAPCAP” additive.
The Effects of Reclaimed Asphalt Pavement (RAP) on the Laboratory Performances of Hot Mix Asphalts
2009
The use of reclaimed asphalt pavement (RAP) in flexible pavement surface layer has been a major sensitive issue in the construction industry. Due to limited space available in landfills, the amount of high quality virgin aggregate declines, and the high price of oil, the use of RAP in new asphalt concrete mixtures has become very attractive. This research has been conducted to study the laboratory performances of HMA mixture containing RAP, in which thermal, fatigue, rutting, moisture sensitivity, and resilient modulus characteristic were evaluated. A Marshall mix design 19 mm mixture containing 0% RAP with binder grade of PG64-22 and PG64-28NV were used as the control mixtures for evaluating properties of mixtures containing 15% and 30% RAP for three different sources of RAP which include one fresh plant waste RAP material. The effects of RAP on the laboratory performances of RAP added HMA mixture depends on type of RAP, amount of RAP, target binder grade to be produced, mixture pe...
Transportation Research Record: Journal of the Transportation Research Board, 2018
Laboratory-based studies have been conducted considering the incorporation of warm mix asphalt (WMA) technologies in paving mixtures both excluding and including reclaimed asphalt pavement (RAP). However, little research has been conducted to date that further advances the knowledge of WMA technologies in combination with high RAP contents beyond experiments using laboratory fabricated mixtures. The objective of this study was to expand on the existing laboratory research by investigating the moisture susceptibility, fatigue cracking and thermal cracking performances of plant-produced mixtures incorporating various WMA technologies and RAP contents. Nine 12.5-mm superpave mixtures were produced in two drum plants using three WMA technologies and three RAP contents. The three WMA technologies used were wax-based SonneWarmix™, chemical-based Evotherm®, and the Stansteel ACCU-SHEAR™ foaming process. Post production moisture in each mixture was negligible, which means that moisture had ...
Performance evaluation of warm mix asphalt mixtures incorporating reclaimed asphalt pavement
Warm mix asphalt (WMA) technology provides not only the production of asphalt pavement at a lower temperature than the temperature maintained in Hot Mix Asphalt (HMA) but also encourages the utilization of Recycled Asphalt Pavement (RAP) and therefore saves energy and nonrenewable resources as well as reduces emissions and fuel consumption. This paper describes the feasibility of utilizing four different WMA additives (organic, chemical, synthetic zeolite and natural zeolite) with different rates of RAP. Following the determination of optimum RAP content corresponding to each WMA additive, Marshall analysis, indirect tensile stiffness modulus and fatigue behavior of HMA and WMA involving RAP were analyzed and compared with control specimens. Hamburg wheel tracking device was also utilized to evaluate the permanent deformation characteristics of mixtures containing optimum RAP content.
Fatigue and Stiffness Evaluations of Reclaimed Asphalt Pavement in Hot Mix Asphalt Mixtures
Journal of Testing and Evaluation, 2011
The recycling of existing asphalt pavement materials produces new pavements with considerable savings in material, money, and energy. Understanding the ability of an asphalt pavement containing reclaimed asphalt pavement (RAP) to resist fracture from repeated loads is essential for the design of hot mix asphalt (HMA) mixtures. However, reaching a better understanding of fatigue behaviors of these pavements continues to challenge researchers all over the world, particularly, as recycled materials with more complex properties are being used in HMA pavements. This study explores the utilization of the conventional fatigue analysis approach in investigating the fatigue life of asphalt mixtures containing RAP. The fatigue beams were made with two asphalt binders, two aggregate sources, four RAP contents (0 %, 15 %, 25 %, and 30 %), and tested at 5 and 20°C. A total of eight mixtures was evaluated and 64 fatigue beams were tested in this study. The test results indicated that the addition of RAP, as expected, increased the viscosity, G ء sin␦, and creep stiffness values while reducing the m-values. However, no obvious trends were found for stiffness and fatigue life of mixtures as the RAP content increased. Statistical analysis results indicated that for binders and mixtures containing 30 % RAP, the utilization of softer binder significantly decreased the viscosity, G ء sin␦, and creep stiffness values; however, there were no significant differences in the stiffness and fatigue life values of these mixtures.
Development of guidelines for usage of high percent RAP in warm-mix asphalt pavements
2011
Road construction using warm-mix asphalt (WMA) has been rapidly gaining popularity in the United States, in part because WMA is believed to be friendlier to the environment as compared to hot-mix asphalt (HMA). Parallel to this rapid growth in WMA construction is utilization of reclaimed asphalt pavement (RAP) in road construction. Research was conducted to develop guidelines for using high percentages of RAP in WMA. The laboratory work was focused on three WMA technologies: water foaming, a chemical additive (Evotherm™), and an organic additive (Sasobit™). The work included RAP characterization, mix design, moisture damage evaluation, and rutting evaluation using the Superpave Shear Tester and Model Mobile Load Simulator Third Scale. Accelerated load testing was conducted at a temperature range of approximately 42 to 50°C for 400,000 cycles of loading. Rutting resistance of the mixes was rated as fair to good. This research indicates that it is possible to produce WMA with high RAP...
To increase RAP materials by up to 75% by binder replacement, a fractionation method was applied to the RAP stockpile by discarding RAP materials passing No. 16 sieve. This fractionation method was effective in improving volumetric properties of the HMA mixture with high RAP contents. The mix designs were then performed for both HMA and WMA with varying fractionated RAP amounts accounting for a replacement of 20, 30, 40, 50 and 75% of the mixture’s optimum asphalt binder content. All mix designs met the Iowa DOT mix design requirements except the one with 75% RAP materials by binder replacement due to the excessive amount of dust content. Hamburg Wheel Tracking (HWT) test was used to evaluate the rutting and moisture susceptibility of both HMA and WMA mixtures with varying RAP amounts. Overall, HMA mixtures performed better than WMA mixtures and the mixes with higher RAP amounts performed better except the mix with 30% RAP materials by binder replacement. Both HMA and WMA mixes with...