Asfalt campuran suam (WMA) adalah teknologi asfalt lestari yang telah dimajukan
sejak kebelakangan ini. Ia bertujuan mengurangkan kos penghasilan asfalt,
penggunaan tenaga serta pelepasan gas toksik. Beberapa isu yang berkaitan dengan
pelaksanaan asfalt campuran suam meliputi pengaruhnya kepada kelembapan dan ubah
bentuk kekal. Justeru, kajian yang lebih mendalam diperlukan untuk menilai ciricirinya.
Kajian ini menilai kesan gabungan penuaan dan kelembapan ke atas HMA dan
WMA dengan gabungan 0.3% bahan tambah suam yang dinamai Cecabase. Spesimen
WMA dicampur pada suhu 140oC dan 120oC. Spesimen kemudiannya didedahkan
kepada dua jam pelaziman suhu manakala separuh daripada jumlah bilangan spesimen
kemudiannya melalui proses penuaan secara jangka panjang. Spesimen tanpa penuaan
dan penuaan didedahkan kepada tiga pelaziman kelembapan yang berbeza iaitu kering,
satu kitaran beku-cair dan tiga kitaran beku-cair. Selepas itu, ujian ricih Leutner dan
ujian separuh lenturan bulat dijalankan ke atas spesimen. Selepas ujian, imej
permukaan pecah spesimen diambil dan kemudian analisis imej dijalankan
menggunakan perisian ERDAS IMAGINE versi 9.1. Daripada analisis imej, spesimen
yang melalui proses penuaan dan pelaziman mempamerkan peratus kegagalan
pelekatan yang paling tinggi, manakala spesimen yang tidak didedahkan kepada
penuaan dan pelaziman mempamerkan peratus kegagalan pelekatan yang paling
rendah. Ini bermakna kegagalan pelekatan meningkat dengan bilangan kitaran
pembekuan dan pencairan yang berganda. Proses penuaan meningkatkan kekuatan
tegangan dan daya ricih campuran asfalt manakala proses pembekuan dan pencairan
menghasilkan keputusan sebaliknya. Juga didapati, HMA mempamerkan rintangan
kelembapan yang lebih tinggi berbanding dengan WMA. Peratus pemecahan agregat
tiada bergantung kepada proses penuaan dan kaedah pelaziman.
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Warm Mix Asphalt (WMA) is a sustainable asphalt technology that has been developed
recently. It is aimed to reduce asphalt production cost, energy consumption as well as
toxic gas emissions. Some issues associated with the implementation of WMA
includes its susceptibility to moisture and rutting. Hence, a detailed study is required to
assess its properties. This study evaluated the combined effects of ageing and moisture
on HMA and WMA incorporating 0.3% warm additive named Cecabase. The WMA
specimens were mixed at 140oC and 120oC. Compacted specimens were then subjected
to two hours of temperature conditioning, while half of the specimens were then
subjected to long term ageing. Three different moisture conditioning namely dry, one
freeze-thaw cycle and three freeze-thaw cycles were induced on the unaged and aged
specimens. Upon conditioning, specimens were then tested for Leutner shear and semicircular
bending (SCB). After the test, images of fractured asphalt specimen surfaces
were captured and image analysis was carried out using ERDAS IMAGINE version
9.1. From the image analysis, the results showed that aged and conditioned specimens
exhibited the highest adhesive failure while unaged and unconditioned specimens
exhibited the lowest adhesive failure. The magnitude of adhesive failure increases with
multiple cycles of freezing and thawing. The ageing process increased specimen
tensile strength and shear force, while the freezing and thawing process resulted in the
opposite. It was also found that HMA exhibits higher moisture damage resistance
compared to WMA. The percentage broken aggregates was independent of ageing and
moisture conditioning.
Evaluation of the combined effects of ageing and moisture on asphalt mixtures using image analysis / Chew Bean Guan