Sains Malaysiana 41(12)(2012): 1595–1603

 

Aging Properties of HMB15 with Varying Binder Film Thicknesses

(Sifat Penuaan HMB15 dengan Ketebalan Filem Perekat yang Berubah)

 

 

Wu Jiantao, Chen Jun & Liu Yun

College of Civil and Transportation Engineering, Hohai University, 1 Xikang Road, Nanjing, Jiangsu Province 210098, China

 

Nur Izzi Md. Yusoff*

Department of Civil and Structural Engineering, Universiti Kebangsaan Malaysia

43600 Bangi, Selangor, Malaysia

 

Mohd. Rosli Hainin

Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310, Skudai, Johor, Malaysia

 

Gordon D. Airey

NTEC, University of Nottingham, University Park, Nottingham

NG7 2RD, United Kingdom

 

Diserahkan: 15 Mei 2012  / Diterima: 20 Julai 2012

 

 

ABSTRACT

In order to cope with the ever-increasing traffic loading and to minimise the cost of road construction and maintenance, several road trials of high modulus base (HMB) materials containing a 15 penetration grade bitumen (known as HMB15) have been carried out in the UK since 1990s. It has been showed that, although HMB15 behaved in a similar way to conventional dense bitumen Macadam with a cost saving of approximately 25%, its long-term durability (aging and moisture damage) is still a major concern of researchers as considerable deteriorations have been commonly observed during the ongoing investigations on cored samples from the sites (either with or without traffic loading). The aim of this paper was to quantitatively show the relationship between aging properties of HMB15 and its binder film thickness (binder content), so that an optimum binder content could be determined. In order to achieve this, 5 groups of cylindrical HMB15 specimens with different binder contents (3.5%, 4%, 4.5%, 5% and 5.5%) were fabricated and subjected to SHRP long-term oven aging test (at 85^oC for 5 days), their mechanical properties both before and after aging simulation were tested using indirect tensile stiffness modulus (ITSM) tests. In addition, binders were recovered at different aging stages and their rheological characteristics were investigated with dynamic shear rheometer (DSR) tests. Based on these, aging indices of different groups were calculated and their mathematical relationship with binder film thicknesses was regressed. The results showed that the aging properties of HMB15 mixtures were significantly affected by their binder film thicknesses. However, regression analysis between aging indices and binder film thicknesses indicated that, as the binder film becomes thicker than 9.5 μm, the change of aging indices with film thicknesses becomes minor and therefore, a film thickness of approximately 9.5 μm was recommended for HMB15 mixtures.

 

Keywords: Aging; DSR; film thickness; HMB15; ITSM

 

ABSTRAK

 

Dalam usaha untuk berdepan dengan beban trafik yang semakin meningkat dan mengurangkan kos pembinaan jalan serta penyelenggaraan, beberapa percubaan pembinaan jalan raya daripada bahan tapak modulus tinggi (HMB) yang mengandungi bitumen bergred penembusan 15 (dikenali sebagai HMB15) telah dijalankan di UK sejak tahun 1990-an. Ia telah menunjukkan bahawa, walaupun HMB15 mempunyai ciri yang sama dengan jalan konvensional asfalt berbitumen padat dengan penjimatan kos kira-kira 25%, ketahanan jangka panjang (jangka hayat dan kerosakan akibat kelembapan) masih membimbangkan penyelidik kerana kerosakan yang agak besar telah biasa dilihat semasa siasatan dijalankan ke atas sampel yang dibuang dari tapak kerja (dengan atau tanpa muatan lalu lintas). Tujuan kajian ini dijalankan adalah untuk mengkaji hubungan kuantitatif antara sifat penuaan HMB15 dan ketebalan filem pengikat (pengikat kandungan), supaya kandungan bitumen yang optimum dapat ditentukan. Bagi mencapai matlamat ini, lima kumpulan HMB15 spesimen silinder dengan kandungan pengikat yang berbeza (3.5%, 4%, 4.5%, 5% dan 5.5%) telah direka dan tertakluk kepada SHRP ujian ketuhar penuaan jangka panjang (pada 85^oC selama 5 hari), sifat-sifat mekanik mereka sebelum dan selepas simulasi penuaan telah diuji dengan menggunakan ujian kekukuhan tegangan tidak langsung modulus (ITSM). Di samping itu, pengikat pulih pada peringkat usia yang berbeza dan ciri-ciri reologi mereka dikaji dengan reometer ricih dinamik (DSR). Berdasarkan ini, penuaan indeks kumpulan-kumpulan yang berbeza telah dikira dan hubungan matematik dengan filem pengikat ketebalan telah mengurang. Keputusan menunjukkan bahawa sifat penuaan HMB15 campuran ini secara ketara dipengaruhi oleh ketebalan filem pengikat. Walau bagaimanapun, analisis regresi antara indeks penuaan dan ketebalan filem pengikat menunjukkan bahawa, apabila filem pengikat menjadi tebal daripada 9.5 μm, perubahan penuaan indeks dengan ketebalan filem menjadi kecil dan dengan itu, ketebalan filem kira-kira 9.5 μm disyorkan untuk HMB15 campuran.

 

Kata kunci: DSR; HMB15; ITSM; ketebalan filem; penuaan

RUJUKAN

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*Pengarang untuk surat-menyurat;  email: izzi@eng.ukm.my