The life of the pavement affected by several factors that play a main role in the performance of asphalt pavement, one of these factors the failure modes, can be represented the important factors that reduced the service life of flexible pavements. Fatigue cracking failure of all the types of failures modes, it is still considered the most common failure mode in recent years. Improvement the performance of pavement by good field works or by enhancing the properties of HMA mixtures represents the essential target by engineers to reduce the maintenance cost and to mitigate potential safety problems. Therefore, this study aims to assess the effect of polymer modified asphalt (PMA); waste material namely crumb rubber with low density polyethylene (LDPE) were used as a combined admixture or as single additive as a sustainable material to enhance the fatigue properties of thin overlay asphalt mixture. 15% of 250-micron crumb rubber was added, while 2.5, 5, 7.5, and 10 % LDPE were added to produce PMA. The flexural beam fatigue test was performed at temperature of (20 °C) to describe the fatigue life of modified thin overlay asphalt mixtures. Results exhibit the vital role of crumb rubber in increase the fatigue life of the mix as compared to conventional mixtures, while LDPE showed a significant role in increase fatigue life of thin overlay asphalt mixture. Fatigue life increase when the 15% of Crum Rubber Modifiers added to the binder. Also fatigue life increase when low density polyethylene (LDPE) added for a high percentage; from the analysis of the result that asphalt mixtures contain (7.5% and 10%) low density polyethylene (LDPE) in addition of 15% of Crumb Rubber Modifier (CRM) achieved the best fatigue life because of the effect of modifiers properties such as flexibility, elasticity, as well as laboratory conditions. Thus, this emphasis the ability of waste material to enhance the asphalt mixture and upgrade such mixture in a sustainable approach.
Permanent deformation (rutting) of asphalt pavements has a major impact on the service life of pavements. Rutting reduces the performance of the pavement and produces serious hazards for highway users. Due to the axle loads incensement, and high local summer temperature, rutting became the major distress in flexible pavements for many countries. Recently, thin asphalt overlay (TAO) is recommended as a significant remedy technique for deteriorated pavements. Aggregates are one of the main structure materials asphalt paving mixtures, whereas, aggregate properties remarkably effected on the asphalt pavements performance. Aggregate gradation is representing the significant feature of aggregates that affecting permanent deformation of traditional hot mix asphalt (HMA) thick pavement layers. The aim of this study is to examine the influence of aggregate gradation differences on rutting features of modified TAO mixtures that comprising waste polymers. The evaluation process included the preparation of polymer modified asphalt (PMA) comprising two types of additives, namely, Crumb Rubber Modifier (CRM) and Low-Density Polyethylene (LDPE). CRM and LDPE in the form of fines that have a particle size under 250 um were used as additives to liquid neat asphalt, individually and collectively by weight of virgin asphalt; i.e., PMA included 15.0% of CRM and (2.5. %, 5.0%, 7.5% and 10.0% of LDPE. Three types of aggregate gradations were used, i.e. 12.5, 9.5 and 4.75mm, Nominal maximum aggregate size, (NMAS). The Superpave mix design system was adopted in volumetric proportioning of prepared mixtures, while Wheel Tracking (WT) test was used to determine the rut depth characteristics for prepared mixtures. about 30 asphalt concrete specimens were prepared to forecast the TAO behavior concerning permanent deformation for wearing course type III A and B according to State Corporation of Roads and Bridges in Iraq, while for 4.75mm, NMAS (sand asphalt layer) an abroad specification was used. Results demonstrated that the aggregate gradation plays a vital role in increasing permanent deformation for several type of TAO mixtures. Also, the addition of CRM by 15% to the neat asphalt led to an increase in the resistance of the mixture to permanent deformation. Moreover, PMA with LDPE became hardener (higher viscosity) which led to increase binder stiffness, whereas a consequent is stiffening the mixture. Therefore, optimizing aggregate gradation with PMA including waste polymers can limited the rutting occurrence distinguishably
Nowadays, Polymer Modified Binder (PMB) is necessary due to its valuable characteristics on asphalt pavement layers with increase in traffic volume and loads. However, current trend in asphalt modification is prefer the waste and by product materials for ensuring the sustainability and cost effectiveness. Therefore, to analyze the effect of waste Crumb Rubber Modifier (CRM) and waste Low-Density Polyethylene (LDPE) on the asphalt binders’ physical properties, CRM/LDPE modified asphalts with different contents were prepared and investigated in this study. Measured physical characteristics were softening point, penetration, ductility and viscosity tests. Conversions of CRM and waste LDPE to functional materials have been introduced in this research study as a practical approach to improve the asphalt binder’s physical properties. CRM and LDPE in the form of fine having a particle size under 250 µm were used as additives to liquid asphalt, individually and collectively by weight of virgin asphalt, i.e., (5.0%, 15.0% and 25.0% of CRM) and (2.5. %, 5.0%, 7.5% and 10.0% of LDPE), after mixed with CRM and LDPE, the asphalts showed decrease in penetration, increase in softening point and rotational viscosity. This referring that both intermediate and high temperature rheological characteristics of the asphalts have been improved by the modification of waste CRM and LDPE, because that mean the stiffness of asphalt binder increases when changing these characteristics and Thus, the asphalt mixture will become more stiff and resistant to possible failures, the Physical properties of the CRM or LDPE modified asphalts are largely dependent on the waste CRM or LDPE content, and many other enhanced characteristics of the mechanical aspect can be targeted using the composite of both CRM and LDPE. However, such result confirms the validity of waste polymer in modifying the asphalt binder.
As the climate temperature decreases, the flexible pavement will be subjected to high tensile stresses which exceeding to the movement resistance of asphalt binder leading to low temperature cracking. SHRP identified a Bending Beam Rheometer (BBR) for measuring the value of flexural-creep stiffness of asphalt binder at low temperatures which consider this value a good indicator for resistance of low-temperature cracking. This study developed a method for measuring the flexural-creep stiffness of asphalt binder by modification of an apparatus instead of Bending Beam Rheometer due to its expensive cost and unavailable in most research laboratories. A (40-50) penetration grade of asphalt binder used in this study at different test temperatures (-5, 0, 5)°C. The experimental results indicate to the modified apparatus and developed test is suitable for testing an asphalt binder at different temperature and loading time.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.