PENGARUH BAHAN TAMBAH GILSONITE PADA ASPHALT CONCRETE WEARING COURSE (ACWCI) TERHADAP NILAI PROPERTIES MARSHALL DAN MODULUS KEKAKUAN

Abstract

ABSTRACT Aggregate super pave gradation, which is used on upper layer of mixed asphalt aggregate, is aimed to increase its performance by controlling permanent deformation (rutting), low temperature cracking and fatigue cracking. Super pave gradation identified by control points and restricted area. Gilsonite material, which is mine product in United State and it is sold on market, is used to improve mixed asphalt to aggregate performance. Application of gilsonite in Pen 60/70 is aimed to reduce its sensitivity to temperature decreasing, as Indonesia is located on tropical Climate. This research is carried out on mixed surface layer of ACWCI aggregate with maximum size 19 mm by using PRD. Variation of gilsonite increment are 0%, 2%, 4%, 6%, 8% to total asphalt content and variation of temperature are 20° C, 40° C, and 60° C. The result of Marshall experiment is used to analyses modulus stiffness of mixed by Brown and Brunton method (1984). The effect of gilsonite on ACWC I is proved statistically by using correlation and regression at significant level a — 0,05. Marshall experiments on ACWCI obtained the optimum asphalt content of 5,9% to total mixed. Additional of 0%, 2%, 4%, 6%, 8% gilsonite cause increasing density till 2,390 gr/cc at 8% gilsonite, reducing VIM value till the lowest at 2,74% for 8% gilsonite, reducing VMA with the lowest at 14,32%, increasing VFA with the highest at 80,86%, the highest stability at 1.922,40 kg., reducing flow with the lowest at 2,04 mm and Marshall Quotient increasing with the highest at 875 kg/mm. The increment of modulus :stiffness ratio, between additional 2%, 4%, 6%, 8% gilsonite and 0% gilsonite at temperature 20° C are 0,998; 1,199; 1,306; 1,556; and at temperature 40° C are 1,202; 1,729; 2,305; 3,148. Modulus stiffness at 60° C could not be identified by Brown and Burton Method as the mixed is unelastic condition. Significant level of one side correlation coefficient for probability side of temperature is -0,000, gilsonite is 0,005 which mean there is correlation and have the real quality . For f (calculated) = 248,495 > f(table) = 3,905, significant level 0,00 < 0,05 indicates that gilsonite and temperature together give effects on modulus sinless. Additional of gilsonite material on ACWCi can be used to increase its performance and its suitable for heavy traffic and hot climate. The amount of gilsonite used have to be considered so that ACWCI still in flexible condition. A BSTRA KSI Agregat bergradasi superpave yang digunakan pada lapis permukaan campuran agregrat aspal bertujuan untuk meningkatkan kinerja campuran tesebut dengan mengontrol deformasi permanen (runing),retak pada temperatur rendal(/ow temperaittre cracking),dan keretakan akibat kelelahan (fatigue cracking). Gradasi superpave ditandai dengan adanya titik-titik kontrol dan dadrah penolakan. Bahan gilsonite merupakan hash! tambang di Amerika Serikat dan banyak dijual dipasaran, dengan maksud untuk memperbaiki kinerja campuran, pengunaan bahan tambang gilsonite pada aspal pen 60/70 agar kepekaan terhadap temperatur berkurang mengingat iklim tropic di Indonesia. Penelitian dilakukan terhadap campuran lapis permukaan ACWCI ukuran agregrat maksimum 19 mm dengan metode kepadatan mutlak. Variasi penambahan gilsonite adalah 0%, 2 910, 4 %, 6 %, 8 % terhadap total kadar aspal dengan variasi temperatur 20° C, 40° C, 60° C. Hasil uji Marshall digunakan untuk menganalisis modulus kekakuan campuran metode Brown dan Bruton (1984). Untuk membuktikan pengaruh gilsonite terhadap ACWCI dilakukan pendekatim statistik dengan uji korelasi dan regresi tingkat signifikansi oc = 0,05. Hasil penelitian percobaan Marshall pada kadar optimum 5,9% terhadap total campuran, penambahan 0%, 2%, 4%, 6%, 8% gilsonite mengakibatkan kenaikan density hingga 2,390 grain/cc pada 8% kadar gilsonite. Nilai 1//Ail mengalami penurunan dan terendah adalah 2,74% pada 8% gilsonite. VMA mengalami penurunan terendah 14,32%, mengalami kenaikkan tertinggi 80,86%, stabilitas tertinggi 1922,40 kg, flow mengalami penurunan terendah 2,04 mm, Marshall Quotient mengalami kenaikkan tertinggi 875 kg per mm. Terjadi peningkatan rasio modulus kekakuan dengan penambahan 2%, 4%, 6%, 8% gilsonite terhadap 0% gilsonite pada temperatur 20°C adalah 0,998; 1,199; 1,306; 1,556; dan pada temperatur 40° C adalah 1,202; 1,729; 2,305; 3,148. Untuk temperatur 60° C nilai modulus kekakuan tidak dapat dihasilkan oleh metode Brown dan Brunton (1984) karena campuran sudah tidak berada dalam kondisi elastis. Tingkat signifikansi koefisien korelasi satu sisi dart segi probabilitas untuk temperatur = - 0,000 , gilsonite = 0,005 berarti mempunyai hubungan dan bersifat nyata. Untuk f(hitung) = 248,495 > f (tabel) = 3.905 tingkat signifikansi 0.00 < 0.05 menandakan bahwa gilsonite dan temperatur bersama-sama memberikan pengaruh terhadap modulus kekakuan. Sehingga bahan tambah gilsonite dapat digunakan untuk meningkatkan kinerja campuran ACWCI dan cocok untuk lalu lintas berat dan iklim panas. Perlu diperhatikan jumlah gilsonite yang dipergunakan agar ACWCI masih tetap dalam kondisi fleksibel.