International Journal of Engineering Research and Technology. ISSN 0974-3154, Volume 13, Number 12 (2020), pp. 4156-4162 © International Research Publication House. http://www.irphouse.com 4156 Dynamic Shear Rheometer to Measure the Improvement of Asphalt Properties with the Addition of Buton Natural Asphalt-Rubber (BNA-R) Sigit Pranowo Hadiwardoyo 1,* , R. Jachrizal Sumabrata 2 , Nurul Wahjuningsih 3 Department of Civil Engineering, Faculty of Engineering, Universitas Indonesia, Depok 16242, Indonesia. ORCID: 1) 0000-0001-8734-4794; 2) 0000-0003-3668-4734, 3) 0000-0003-4587-7490 Abstract The characteristic of asphalt was influenced from temperature and load. Modifications of the characteristics of asphalt can improve their performance. Changes to the complex shear modulus will affect the stiffness modulus of asphalt. Indonesia has considerable deposits of natural asphalt, namely Buton natural asphalt, which has the potential to be used as an asphalt modifier. Buton natural asphalt-rubber (BNA-R) is one of the products of Buton natural asphalt mixed with rubber. This study uses a dynamic shear rheometer (DSR) to examine the effects of BNA-R on the rheology of virgin asphalt. Tests were carried out on samples before and after aging. The added quantity of BNA-R was varied from 2.5 % to 20 % with respect to Pen 64.2 virgin asphalt. The addition of BNA-R increased the hardness and improved the rheological properties of asphalt by increasing its performance grade (PG) and complex shear modulus (G*). The black diagram and master curve analysis show that the phase angle value (δ) decreases with the addition of BNA-R and increases the resistance to temperature. Keywords: Modified Asphalt, Stiffness Modulus, Complex Shear Modulus, Buton Asphalt Rubber, Temperature I. INTRODUCTION Asphalt or bitumen is one of the oldest building materials and has been used extensively since ancient times. Initially, natural asphalt was processed at high temperatures to remove oil fractions and maintain high molar mass. Asphalt materials show thermoplastic properties and because of their superiority to water and their adhesive properties, they are used in various applications. Currently, asphalt is produced from crude oil via distillation, where an increase in temperature reduces the volatile-component content. Bitumen is a complex hydrocarbon which is regarded as a colloidal system consisting of high molecular weight asphaltenes dispersed in a lower molecular weight maltenes [1], [2]. Deposits of natural rock asphalt in Indonesia is found on Buton Island; the material is also known as Asbuton. There is a massive reserve of natural rock asphalt with a 5-30 % asphalt content and the estimated deposit amount is up to 677 million tons [3]. Asbuton has a great chance of being used partially or completely as a substitute for asphalt oil in asphalt mixtures. Asbuton is produced by extracting Buton rock asphalt and is more widely used as a modifier or added material because its penetration is extremely low [4]. Buton natural asphalt-rubber (BNA-R) is a mixture of Buton rock asphalt and crumb rubber. BNA-R contains 60 % asphalt as a result of semi-extraction from Buton rock asphalt and 40 % crumb rubber and has several advantages such as high stickiness, high softening point, high stiffness modulus, high resistance to fracture, and a durable and economical value [5], [6]. A mixture of asphalt and aggregates produces a heterogeneous material, generally consisting of original or used aggregates (recycled from industrial processes or otherwise), an asphalt binder, and air cavities. The mechanical properties of aggregate asphalt mixtures are mainly influenced by the nature of the asphalt. In general, aggregate asphalt mixtures show a time-dependent behavior with a characteristic nonlinear visco elastic stress-strain response (except under very low stresses or strains) [7]. As a thermoplastic material, asphalt has visco elastic properties under the conditions of most pavement operations. These properties determine the behavior of asphalt mixtures, usually measured by the relationship between stress and strain. The rheological properties of asphalt are usually presented in the form of complex shear modulus curves (G*) and phase angles (δ). G* is defined as the ratio of maximum stress (shear) to maximum strain when experiencing shear loads. δ is the phase difference between the voltage and strain in harmonic oscillation. Furthermore, the master curve helps to understand the behavior of asphalt binders for various loading frequencies under different temperature conditions. The main laboratory equipment for obtaining these parameters is a dynamic shear rheometer (DSR). Even at low temperature, the DSR still suitable to investigate the rheological properties of bitumen [8]–[13]. One of the most common flexible pavement damage in high- temperature countries such as Indonesia is rutting. The Superpave rutting factor (G*/Sin δ) has been used to evaluat e the potential resistance to rutting of asphalt at high temperatures [11]. Other researchers call this value an anti- rutting factor [8], [14]–[18]. G*/Sin δ is derived from the dissipation energy concept (ΔU) (AASHTO T315-15). The ΔU value for the loading cycle can be calculated using Eq. (1) [11]. ∆ =       (1) where ε max is the maximum shear strain, σ max is the maximum shear stress, and δ is the phase angle. Under stress