The Effect of Technical Natural Rubber Mastication with Wet Process Mixing on the Characteristics of Asphalt-Rubber Blend

Abstract The modification of asphalt with natural rubber is believed to enhance asphalt penetration grade (Pen Grade) 60/70. Natural rubber-type technical natural rubber with standard Indonesian rubber (SIR) 20 was chosen as an asphalt additive. However, SIR 20 as an asphalt additive directly has the rubber distribution problem in asphalt, which tends to accumulate in certain parts of the asphalt mixture. Also, the use of SIR 20 requires a very long time in the mixing process to reach homogeneity. This study aims to determine the effect of adding technical natural rubber, Standard Indonesian Rubber (SIR) 20, both with and without mastication, on the characteristics of asphalt-rubber blends. The asphalt-rubber blend was developed by melting the SIR 20 at 200 °C before mixing it with asphalt under the melting point (170 °C). Evaluation of asphalt-rubber performance is measured using tests on penetration, softening point, and Marshall stability. While the asphalt rheological characteristics reviewed are complex modulus (G*), phase angle (δ), rutting factor (G* / Sin δ) before and after short-term aging. The results showed that the mastication process of SIR 20 could accelerate the asphalt-rubber mixture's homogenization process and produce asphalt with increased performance at high temperatures. The results show the addition of 10% MSIR has the best performance with a penetration value of 58.5 dmm, a softening point of 59.1 °C, Marshall stability of 1710 kg, and rutting factor of 5.46 kPa.