Use of Ahlat stone powder for expansive subgrade stabilization

Abstract

Expansive subgrades pose significant challenges to road pavements due to their inherent high volume change potentials and poor load-bearing capacities. This paper focused on the stabilization of the expansive subgrade with Ahlat stone powder (ASP). For this purpose, the soil was replaced with ASP in ratios of 3%, 6%, 9% and 12% by dry weight and a series of physical and mechanical laboratory tests consisting Atterberg limits, swelling/shrinkage, compaction, unconfined compressive strength (UCS) and California bearing ratio (CBR) were performed on specimens with/out ASP. Additionally, scanning electron microscope (SEM) analysis was conducted to monitor the microstructural changes through stabilization. The test results indicated that liquid limit (LL), plasticity index (PI) and swell/shrink potential of soil was reduced consistently with increasing ASP content. The maximum dry density (MDD) of the soil increased, while optimum moisture content (OMC) was reduced steadily with ASP. The UCS and CBR values of soil with a 9% ASP content increased by 55% and 39%, respectively. Considering the CBR values, a reduction of approximately 24% in the required subbase thickness can be achieved with a 9% ASP ratio. The SEM analyses revealed a more compact with less porous microstructure of soil after stabilization.

Keywords

• Expansive subgrade
• Ahlat stone powder
• Stabilization
• CBR
• UCS

Genleşen yol taban zeminleri stabilizasyonunda Ahlat taşı tozunun kullanımı

Abstract

Genleşen taban zeminleri, doğal yüksek hacim değişim potansiyelleri ve düşük yük taşıma kapasiteleri nedeniyle yol kaplamaları için önemli zorluklar oluşturmaktadır. Bu çalışma, genleşen taban zeminlerin Ahlat taşı tozu (ASP) ile stabilizasyonuna odaklanmıştır. Bu amaçla, taban zemini %3, %6, %9 ve %12 oranlarında ASP ile kuru ağırlıkça ikame edilmiş ve Atterberg limitleri, şişme/büzülme, kompaksiyon, serbest basınç dayanımı (UCS) ve Kaliforniya taşıma oranı (CBR) deneylerini içeren bir dizi fiziksel ve mekanik laboratuvar testleri ASP'li/ASP'siz zemin numuneleri üzerinde gerçekleştirilmiştir. Ayrıca, stabilizasyon yoluyla zemin yapısında meydana gelen mikro yapısal değişimleri izlemek amacıyla taramalı elektron mikroskobu (SEM) analizi gerçekleştirilmiştir. Deney sonuçları, zeminin likit limiti (LL), plastisite indeksi (PI) ve şişme/büzülme potansiyelinin ASP içeriğinin artmasıyla tutarlı bir şekilde azaldığını göstermiştir. Zeminin ASP içeriğiyle maksimum kuru yoğunluğu (MDD) artarken, optimum nem içeriği (OMC) istikrarlı bir şekilde azalmıştır. %9 ASP içeriğine sahip toprağın UCS ve CBR değerleri sırasıyla %55 ve %39 oranında artmıştır. CBR değerleri dikkate alındığında, %9 ASP oranıyla gerekli alt taban kalınlığında yaklaşık %24'lük bir azalma elde edilebileceği ortaya koyulmuştur. SEM analizleri, stabilizasyon sonucu sonra zeminin daha az gözenekli ve daha kompakt bir mikro yapıya sahip olduğunu ortaya koymuştur.

Keywords

• Genleşen taban zemini
• Stabilizasyon
• Ahlat taşı tozu
• CBR
• UCS

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