International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 02 | Feb -2017
p-ISSN: 2395-0072
www.irjet.net
Rutting Assessment of Crumb Rubber Modifier Modified Warm Mix Asphalt Incorporating Warm Asphalt Additive Ahmad Batari*1, Mohamad Y. Aman2, Saeed M. Saeed1, T. Y. Ahmed1 , A. U. Chinade1 1Lecturer,
Department of Civil Engineering, Abubakar Tafawa Balewa University, PMB 0248, Bauchi, Nigeria. Professor, Faculty of Civil and Environmental Engineering, University Tunn Hussein Onn Malaysia, 86400 Parit Raja, Johor Malaysia ---------------------------------------------------------------------***--------------------------------------------------------------------2Associate
Abstract - Warm Mix Asphalt (WMA) as a green
technology, permits production of asphalt mixtures at lower temperatures compared to conventional HMA; emissions and energy consumption reduction, were among the key success of this technology, thus, enhancing social, economic, and environmental sustainability. But due to the reduced production temperature, WMA are more prone to rutting, to improve the rutting resistance of WMA mixtures and minimize pollution resulting from waste rubber tire. Therefore, the effect of wet processed Crumb Rubber Modifier (CRM) on rutting depth of WMA mixtures incorporating 2.5% Sasobit by weight of base binders were assessed in the laboratory. In this study, the asphalt mixtures were fabricated in accordance with Superpave, using; crush granite aggregate of 9.5mm NMAS and the four binders that were produced by blending the PG 64 binder with different contents of 40 mesh size CRM (0%, 5%, 10%, and 15%, by weight of the base binder). Rutting depths of the mixtures were assessed on 150mm diameter and 70mm thick cylindrical samples using wheel tracker, the wheel tracking test were carried out at 45oC and 60oC, in accordance with BS 598 Part 110 (1998). Based on the results of wheel tracking tests, CRM could improve the resistance of the WMA mixtures to rutting. It was also found from statistical Analysis of Variance (ANOVA), that the two influence factors; CRM, and the test temperature both having p-values less than the assumed significance at 95% confidence level, therefore they have significant effect on rutting in WMA. Key Words: Rutting, Crumb Rubber, Warm Mix Asphalt, Sasobit, Wheel Tracking 1. INTRODUCTION Conventional Hot Mix Asphalt (HMA) production at higher temperatures results in intolerable high energy consumption, emissions of greenhouse gasses; exhaust, and odors [1], consequently, Warm Mix Asphalt (WMA) technology was introduced to cut down the production (mixing and compaction) temperatures of asphalt mixtures, to improve working conditions at site, and reduce its impact on the environment. The WMA technology allows asphalt production at 20°C to 30°C temperatures lower than conventional HMA [2]. The WMA is achieved through a variety of different warm asphalt technologies developed to lower the viscosity of the asphalt binder and allow proper © 2017, IRJET
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mixing and compaction at these reduced temperatures. One of the most commonly used additives is a Fischer-Tropsch (FT) wax [3], named Sasobit. Sasobit is completely soluble in asphalt binders at temperatures above 115°C. At temperatures below its melting point Sasobit forms a lattice structure in asphalt binders that is a basis for the stability of asphalts modified with Sasobit [4, 5]. However, some issues arose regarding the performance and durability of WMA mixtures, because at lower production temperatures these mixtures are more susceptible to rutting [6], because the lower production temperature results in reduced aging of the WMA mixtures and increase their rutting potential [5]. Rutting is regarded as one of the major distress in asphalt pavement; it is the accumulation of permanent deformation in asphalt caused by repeated loads at high working temperatures [7]. Rutting affects the pavement ride quality and leads to serious safety issues to road users, rutting in the pavement can cause uncontrollable vehicle sliding with a high potential for traffic accidents [8]. According to Brown et al., [9], rutting is the permanent deformation of asphalt pavement and or the underlying base or sub base caused by repeated traffic loads. This failure mode appears as a depression in the wheel path or as uplift along the sides of the rut. Basically, there are two forms of rutting, the first which is known as surface rutting which is restricted to the uppermost asphalt surfacing layers, this does not adversely affects the structural integrity of the pavement unless it becomes excessive, while the second type which is the main component of rutting arise from the subgrade and is termed structural rutting. Also, the rutting resistance of asphalt mixtures depends on the binder rheology, road temperatures as well as traffic loads [8]. To offset this effect, the selection or use of modifiers to obtain stiffer asphalt binder is recommended [9]. There are a great number of modifiers that are used to improve some properties of asphalt mixtures or to reduce cost, CRM is one of such. Some technical reasons for their use include the following; to improve the overall performance of asphalt mixtures, to reduce life cycle cost of asphalt pavements and to obtain stiffer mixtures at high service temperatures to minimize rutting [8, 10]. On the other hand, the traditional method of waste tires management have been stockpiling or illegally dumping or landfilling, which is short term solution. Annually, about one billion, equivalent 9 million tons waste tires are produced in ISO 9001:2008 Certified Journal
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