Investigation of the Effects of Aggregate Segregation on Asphalt Mixture Compactability

Öz

The compactablility of asphalt mixtures refers to how easily these mixtures can be compacted to reach the target density. Proper compaction of asphalt mixtures is crucial for achieving the expected performance from the mixture. Aggregate segregation is defined as the concentration of coarse aggregates within the mixture in specific areas, and it is an important factor that affects the internal structure of the mixture. In this study, the effects of aggregate segregation on the volumetric properties and compactability of asphalt mixtures were investigated. To simulate different conditions, two groups of specimens were produced, applying the same compaction effort and targeting the same density. Unbiased-homogenous and segregated specimens at two levels were fabricated for each group using the Superpave gyratory compactor. To produce segregated samples, the mixtures prepared by combining the coarse and fine aggregates in the design gradation in different proportions and then placed in the mold in two layers before compaction. The volumetric properties of the produced samples were determined, and the compactability indices of the samples were calculated using the compaction curves. The results show that aggregate segregation significantly affects the volumetric properties and compactability of asphalt mixtures. It was also observed that the compactability of asphalt mixtures decreases with the increasing segregation level, and much more compaction effort is required to produce samples with the same target density.

Anahtar Kelimeler

• Asphalt mixture
• Aggregate segregation
• Compactability
• Superpave
• Compaction energy index

Agrega Segregasyonunun Asfalt Karışımlarının Sıkıştırılabilirliğine Etkilerinin İncelenmesi

Öz

Asfalt karışımlarının sıkıştırılabilirliği, karışımların hedef yoğunluğa sıkıştırılmasının ne ölçüde kolay olduğunu tanımlamak için kullanılmaktadır. Asfalt karışımlarının sorunsuz şekilde sıkıştırılması, karışımdan beklenen performansı elde etmek için çok kritiktir. Agrega segregasyonu karışımdaki kaba agregaların belirli alanlarda kümelenmesi olarak tanımlanmakta olup, karışımın içyapısını etkileyen önemli bir durumdur. Bu çalışmada, agrega segregasyonunun asfalt karışımlarının hacimsel özelliklerine ve sıkıştırılabilirliğine etkileri incelenmiştir. Farklı koşulları simüle etmek için aynı sıkıştırma eforu uygulanarak ve aynı hedef yoğunlukta olmak üzere iki grup numune hazırlanmıştır. Her grup için ön koşulsuz-homojen ve iki seviyede segregasyona uğramış asfalt karışımı numuneleri Superpave yoğurmalı pres kullanılarak üretilmiştir. Segregasyona uğramış numuneler üretmek için tasarım gradasyonundaki kaba ve ince agregalar farklı oranlarda birleştirilerek hazırlanan karışımlar kalıba iki tabaka olarak yerleştirilip sıkıştırılmıştır. Üretilen numunelerin hacimsel özellikleri belirlenmiş ve numunelerin sıkışma eğrileri kullanılarak sıkıştırılabilirlik indeksleri hesaplanmıştır. Sonuçlar, agrega segregasyonunun, asfalt karışımlarının hacimsel özelliklerini ve sıkıştırılabilirliğini önemli ölçüde etkilediğini göstermektedir. Artan segregasyon seviyesi ile asfalt karışımlarının sıkıştırılabilirliğinin düştüğü ve aynı hedef yoğunlukta numune üretebilmek için çok daha fazla sıkıştırma eforu harcanması gerektiği belirlenmiştir.

Anahtar Kelimeler

• Asfalt karışımı
• Agrega segregasyonu
• Sıkıştırılabilirlik
• Superpave
• Sıkışma enerjisi indeksi

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