Analisis Hubungan Karakteristik Konvensional dan Reologi Dinamis Aspal Modifikasi High-Density Polyethylene

Abstract

Kerusakan perkerasan lentur akibat deformasi permanen (rutting) menjadi salah satu permasalahan pada perkerasan jalan di wilayah beriklim tropis. Modifikasi binder menggunakan High-Density Polyethylene (HDPE) berpotensi meningkatkan ketahanan terhadap deformasi permanen melalui perubahan karakteristik konvensional dan reologi dinamis, tetapi hubungan antara kedua karakteristik tersebut pada aspal modifikasi HDPE masih perlu dikaji. Penelitian ini bertujuan menganalisis karakteristik konvensional dan reologi dinamis aspal modifikasi HDPE serta hubungan antara parameter konvensional, proses modifikasi, dan nilai rutting factor. Aspal penetrasi 60/70 dimodifikasi dengan HDPE sebesar 3% hingga 8% menggunakan low shear mixing pada 500 rpm, 180°C, selama 90 dan 120 menit, kemudian dikarakterisasi melalui pengujian penetrasi, titik lembek, dan frequency sweep. Analisis hubungan antarparameter dilakukan menggunakan Random Forest dan Multiple Linear Regression (MLR), sedangkan data frequency sweep dianalisis melalui master curve dan Black diagram. Hasil penelitian menunjukkan bahwa penambahan HDPE menurunkan penetrasi hingga 74%, meningkatkan titik lembek hingga 67%, dan meningkatkan rutting factor hingga 256 kali dibandingkan aspal murni. Peningkatan HDPE juga meningkatkan modulus kompleks (|G*|) dan menurunkan sudut fase (d), yang menunjukkan peningkatan kekakuan dan dominasi respons elastis binder. Hasil pemodelan menunjukkan bahwa kombinasi titik lembek dan proporsi HDPE memberikan representasi terbaik terhadap variasi rutting factor, sedangkan MLR menunjukkan hubungan antara peningkatan proporsi HDPE dengan peningkatan titik lembek dan penurunan penetrasi serta hubungan negatif antara penetrasi dan rutting factor. Temuan tersebut menunjukkan adanya keterkaitan antara perubahan karakteristik konvensional akibat modifikasi HDPE dan respons reologi binder pada suhu tinggi, sehingga parameter konvensional berpotensi digunakan sebagai indikator awal kecenderungan ketahanan terhadap deformasi permanen.

Damage to flexible pavement caused by permanent deformation (rutting) remains one of the major concerns in road pavements in tropical climates. Modifying asphalt binder with High-Density Polyethylene (HDPE) has the potential to improve resistance to permanent deformation by altering its conventional and dynamic rheological characteristics; however, the relationships among these characteristics in HDPE-modified asphalt require further investigation. This study aims to analyze the conventional and dynamic rheological characteristics of HDPE-modified asphalt binder and the relationships among conventional parameters, modification conditions, and rutting factor. Penetration grade 60/70 asphalt binder was modified with 3% to 8% HDPE using low shear mixing at 500 rpm and 180°C for 90 and 120 minutes, followed by penetration, softening point, and frequency sweep tests. Relationships among the parameters were analyzed using Random Forest and Multiple Linear Regression (MLR), while the frequency sweep data were analyzed through master curve and Black diagram. The results showed that adding HDPE decreased penetration by up to 74%, increased the softening point by up to 67%, and increased the rutting factor by up to 256 times compared with the unmodified binder. Increasing HDPE content also increased the complex modulus (|G*|) and decreased the phase angle (d), indicating increased binder stiffness and a greater dominance of elastic response. The modeling results showed that the combination of softening point and HDPE content provided the best representation of variations in rutting factor. At the same time, MLR indicated a relationship between increasing HDPE content and increasing softening point and decreasing penetration, as well as a negative relationship between penetration and rutting factor. These findings demonstrate a relationship between changes in conventional characteristics resulting from HDPE modification and the high-temperature rheological response of the binder, indicating that conventional parameters have the potential to serve as preliminary indicators of the binder's tendency to resist permanent deformation.