Kompaksiyon enerjisi ve geofiber katkı malzemesinin taş ocağı artık malzemesinin mekanik davranışı üzerindeki etkisi
Effects of compaction energy and geofiber reinforcement on mechanical behavior of quarry residuals
Yazar: BEYZA ÖZULU
Danışman: DR. ÖĞR. ÜYESİ BERRAK TEYMÜR ; DR. GÖKHAN ÇEVİKBİLEN
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / İnşaat Mühendisliği Ana Bilim Dalı / Zemin Mekaniği ve Geoteknik Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2024
Konu: İnşaat Mühendisliği = Civil Engineering

Özet:
Tez kapsamında taş ocağı artık malzemelerinin inşaat ve geoteknik mühendisliği açısından yararlı kullanımı ele alınarak bu doğrultuda yürütülen deneyler ve iyileştirme yöntemleri üzerinde yapılan araştırmalara yer verilmiştir. İlgili artık malzemelerin mekanik davranışına ince dane oranlarının, farklı kompaksiyon enerjilerinin ve farklı boy ve oranlardaki geofiber katkı malzemelerinin etkisi İsatanbul Teknik Üniversitesi Zemin Mekaniği ve Geoteknik Mühendisliği Laboratuvarı'nda araştırılmıştır. Taş ocağından temin edilen numunelerin endeks özellikleri belirlendikten sonra yol inşaatı uygulamalarında faydalı kullanım olanakları araştırılmıştır. Bu kapsamda ham artık malzemeler üzerinde standart/modifiye Proctor, yaş CBR (California Bearing Ratio), kesme kutusu ve permeabilite deneyleri, geofiber katkılı artık malzemede de serbest basınç deneyleri gerçekleştirilmiştir.
İlk olarak taş ocağından temin edilen numuneler üzerinde endeks özelliklerini belirlemek üzere kıvam limit testleri ile elek analizi ve hidrometre deneyleri yapılmıştır. Malzemelerin ince dane oranının %25 ~ 49 arasında değişkenlik gösterdiği tespit edilmiştir. Bu çalışmada kullanılmak üzere ince dane oranına göre %49 (N1) ve %25 (N2) olarak iki numune seçilmiştir. Her iki numune için de yapılan standart kompaksiyon deneyleri sonucunda Karayolu Teknik Şartnamesi (KTŞ) göz önünde bulundurulduğunda %5' in altında yaş CBR değerine sahip olan N1 numunesinin (%9) dolgu malzemesi olarak kullanım kriterini sağlamakla birlikte N2 numunesinin de (%16) dolgu malzemesi olarak değerlendirilebileceği belirlenmiştir. Düşen seviyeli permeabilite deney sonuçlarına göre N1 (2,2 x 10-6 m/s) ve N2 (5 x 10-6 m/s) numunelerinin permeabilite katsayılarının 10-5 ve 10-7 m/s arasında yer almasından dolayı düşük geçirgenliğe sahip olduğu ve dolgu malzemesi olarak kullanılabileceği yorumlanmıştır. Kesme kutusu deney sonuçlarına göre ise ince dane oranının azalmasıyla birlikte kayma mukavemeti açısı (°' den 41°' ye yükselmiştir. Her iki numunenin kohezyon değerleri ise ihmal edilebilir mertebede olduğu belirlenmiştir. Elde edilen sonuçlara göre ince dane oranına bağlı olarak yol inşaatı uygulamalarında artık malzemenin faydalı kullanım alanlarının değişkenlik göstereceği sonucuna varılmaktadır.
Standart ve modifiye sıkıştırma enerjisi altındaki elde edilen mukavemet parametrelerinin karşılaştırılması amacıyla her iki artık malzeme üzerinde de yaş CBR, kesme kutusu deneyleri yürütülmüştür. Standart ve modifiye enerji sıkılığında elde edilen yaş CBR değerleri dikkate alındığında modifiye enerjide hazırlanan N1 ve N2 numuneleri için sırasıyla %45 ve %67 olmak üzere daha yüksek değerlere ulaşılmıştır. KTŞ'ye göre üst yapı taban malzemesi için gerekli olan CBR ≥ 20 şartını N1 numunesi sağlarken alt temel taban malzemesi için N2 numunesinin CBR ≥ 50 kriterini sağladığı tespit edilmiştir. Kesme kutusu deney sonuçlarından elde edilen sonuçlar doğrultusunda standart sıkılıktaki N1 ve N2 numuneleriyle ulaşılan ihmal edilebilir kohezyon değerlerinin modifiye sıkılıktaki numuneler için de geçerli olduğu belirlenmiştir. Kayma mukavemeti açısı değerleri N1 ve N2 numuneleri için sırasıyla 43° ve 47° olarak elde edilmiştir. Elde edilen deney sonuçlarına göre kompaksiyon enerjisinin artmasıyla birlikte her iki numunenin mukavemet parametrelerinde iyileşme gözlenmiştir. Ayrıca, yürütülen düşen seviyeli permeabilite deney sonuçlarına göre modifiye sıkılıkta hazırlanan N1 ve N2 numunelerinin sırasıyla 1,2 x 10-6 m/s ve 3,7 x 10-6 m/s katsayılarına sahip olduğu ve kompaksiyon enerjisinin artmasıyla birlikte zemin numunelerinin geçirimliliğinin azaldığı gözlenmektedir.
Önceki çalışmalarda maden artık malzemesinin geotekstil tüp ile susuzlaştırılması sonucunda %49 olan ince dane oranının %20'lere kadar inebildiği gözlenmiştir. Bu çalışmada, geotekstil tüp ile susuzlaştırma sonrası maden artığının taşınması sırasında bertaraf olacak geotekstilin geofiber katkısı olarak susuzlaştırılmış artık malzemede yeniden değerlendirilmesi araştırılmıştır. Bu kapsamda kesilerek hazırlanacak geofiber malzemesi ile maden artık malzemesinin mukavemet parametrelerindeki iyileştirmek amacıyla en uygun boy ve ağırlıkça katkı oranları belirlenmiştir. N2 numunesinin tercih edildiği çalışmada seçilen geofiber katkı ile karıştırılarak standart ve modifiye sıkılıkta hazırlanan numuneler üzerinde serbest basınç deneyleri yapılmıştır. Standart enerji ile sıkıştırılan numunelerde 2 cm ve 2,5 cm boylarında %0,1 geofiber oranı ile en yüksek serbest basınç dayanımını vermiştir. Modifiye enerji altında sıkıştırılan numunede ise 2,5 cm boyunda %0,2 geofiber oranında en yüksek serbest basınç dayanımına ulaşılmıştır. 
Çalışma laboratuvar koşullarındaki deneylerle sınırlı kaldığından saha uygulamaları açısından susuzlaştırılmamış veya susuzlaştırılmış maden artık malzemesinin faydalı kullanım projelerinde istenilen mekanik dayanımına göre bu deney sonuçlarının yorumlanması, kullanılacak geofiber malzemenin boy, katkı oranı ile sıkıştırma enerjisinin seçilmesi gerekecektir. İleriki çalışmalarda, alternatif iyileştirme yöntemleri ile maliyet karşılaştırması yapılması uygun olacaktır.

Abstract:
The process of industrialization and the rapid advancements in technology across the globe have instigated a substantial surge in the demand for both raw materials and energy, consequently setting in motion the quest for diverse and innovative resource exploration endeavors. A prominent and critical economic activity that has the potential to address the escalating energy requirements, influenced significantly by the relentless growth of the global population, is the mining industry. The mining sector assumes a paramount role in fulfilling the burgeoning demand for essential minerals and ores within the developing world. The extraction of vital non-renewable resources, such as minerals and ores, to meet the ever-expanding energy needs necessitates an approach that diligently incorporates principles of engineering and careful resource management. While the primary focus lies in securing a reliable supply of raw materials and energy to sustain economic growth and development, it is imperative not to overlook the inescapable environmental impact stemming from mining activities. Indeed, the implications on the environment call for meticulous consideration and responsible action. In light of heightened environmental awareness, the mining industry is now confronted with the pressing imperative of proactively mitigating the potential adverse effects arising from the utilization of various chemical substances during mining operations. Measures need to be adopted to curb the likelihood of harmful repercussions and to ensure the safeguarding of environmental integrity. To this end, stakeholders in the mining sector must be attuned to environmental sensitivity, and concerted efforts should be made to strike a balance between economic aspirations and ecological preservation. By prioritizing sustainable mining practices, implementing stringent regulations, investing in eco-friendly technologies, and embracing responsible resource utilization, the mining industry can strive to coexist harmoniously with nature while catering to the escalating energy demands of our dynamic world.
Throughout the course of mining operations, beyond the primary goal of raw material extraction, the generation of surplus materials in the form of soil materials and chemical substances may arise. It is crucial to recognize that the occurrence of chemical substance-related concerns is not universally applicable to all mining sites. For instance, in the context of quarry mining, the utilization of chemical substances is generally not a prevalent practice. Instead, the residue materials resulting from quarrying activities are often either stored in proximate mine tailing ponds or repurposed as construction materials for embankment dams, presenting a relatively practical approach. Notwithstanding the convenience of this disposal method for residuals, it is accompanied by several potential adverse consequences. These encompass substantial spatial requirements for storage, elevated construction costs, and engineering intricacies concerning the stability of embankment dams. The stability challenges, in particular, are of paramount concern as they can give rise to critical hazards, leading to potential loss of human life and property. Consequently, to address these concerns effectively and reduce the volume of quarry residue materials at mining sites, while simultaneously mitigating the identified negative impacts, the adoption of reutilization practices emerges as a more sustainable and judicious approach. Within the purview of construction and geotechnical engineering, a strategic exploration and evaluation of suitable filling materials for integration into road construction applications hold immense significance within the ambit of reutilization efforts. By incorporating reutilization strategies, the environmental footprint of mining activities can be notably curtailed, and the overall sustainability of mining operations can be considerably enhanced. The systematic investigation and incorporation of qualified filling materials in road construction applications, aligned with the principles of eco-friendliness and responsible resource management, play an instrumental role in achieving these objectives. In doing so, the management of residuals is optimized, offering an environmentally sound and conscientious approach to modern mining practices.
As part of the research undertaken in this thesis, the exploration of beneficial utilization opportunities for quarry residuals has been comprehensively investigated, with a particular focus on their potential applications in construction and geotechnical engineering. The study delved into a series of experiments and improvement methods to elucidate the feasibility of reusing these residue materials effectively and sustainably. Of significant interest were the influences of key factors, including fine particle content, compaction energy levels, and the incorporation of geofiber additives in varying proportions and ratios, on the strength parameters of the residuals. To rigorously examine these aspects, the research was meticulously conducted at the prestigious Soil Mechanics and Geotechnical Engineering Laboratory of Istanbul Technical University. Initially, the index properties of the samples sourced from the quarry were meticulously determined, providing the essential baseline data for further investigation. Subsequently, a battery of comprehensive tests was employed to analyze the mechanical behavior of the quarry residue materials in light of their potential beneficial utilization in geotechnical engineering applications. The conducted tests comprised the standard/modified Proctor tests, aimed at characterizing the compaction properties and establishing the relationship between water content and dry unit weight. To evaluate load-bearing capacity, soaked California Bearing Ratio (CBR) tests were conducted, providing essential insights into the potential performance of these materials under specific environmental conditions. The direct shear box tests were employed to assess the shear strength parameters, offering vital information for geotechnical engineering applications. Additionally, permeability tests were undertaken to ascertain the potential for water flow through these materials and understand their behavior in terms of fluid movement. Moreover, the research included a crucial examination of the impact of geofiber additives on the mechanical properties of the residuals. This investigation was accomplished through unconfined compression tests, allowing for a comprehensive evaluation of the materials' response to loading conditions when reinforced with geofiber additives. The primary objective of the research was to explore innovative and sustainable approaches to maximize the utilization of quarry residuals, considering their geotechnical properties and mechanical behavior. By generating comprehensive data through laboratory investigations and experimentation, this study aimed to contribute significantly to the development of sustainable civil engineering practices. Ultimately, the findings may foster the adoption of environmentally friendly and economically viable solutions for managing quarry residuals, promoting more efficient and environmentally conscious engineering practices in the industry.
At the outset of the study, meticulous investigations were conducted on the quarry residuals, procured in their pristine state without any incorporation of chemical additives. To elucidate their index properties, a series of tests including consistency limit tests, sieve analysis, and hydrometer tests were carried out. These investigations yielded significant insights into the composition of the materials, revealing that the fine particle content constituted 49% of Sample N1 and 25% of Sample N2. Furthermore, the consistency limit tests provided valuable information concerning the plasticity characteristics of the samples. It was ascertained that both Sample N1 and Sample N2 exhibited non-plastic behavior, indicating that these materials did not possess significant plasticity and were non-cohesive in nature. Subsequent to the determination of index properties, the surplus materials underwent standard compaction tests in adherence to the specifications stipulated in the Turkish National Technical Specification for Highways (TSH). The results unveiled that while Sample N1 attained a CBR value of 9%, above the required threshold of 5%, it is clear that this sample can be used according to the usage criteria for filling material. Besides, Sample N2 exhibited a CBR value of 16%, rendering it eligible for utilization as filling material, too. The permeability characteristics of the samples were thoroughly analyzed through permeability tests, providing crucial data on the permeability coefficients of Sample N1 (2.2 x 10-6 m/s) and Sample N2 (5 x 10-6 m/s). Both samples exhibited low permeability within the range of 10-5 to 10-7 m/s, implying their potential suitability as filling materials, particularly in scenarios that require materials with limited permeabilityThe mechanical properties of the materials were further scrutinized via direct shear box tests. The results revealed a noteworthy trend wherein, as the fine particle content decreased, the internal friction angle (𝜙) increased from 38° to 41°. It was also established that both samples exhibited minimal cohesion values, indicating negligible cohesive strength. Taking into account the comprehensive findings of the study, it is evident that the varying fine particle content may exert a discernible influence on the suitability of the quarry residuals for diverse filling material applications. Hence, when evaluating the potential beneficial utilization of these materials, due consideration should be given to the variation in fine particle content to assess their practical applicability as filling materials for distinct engineering purposes.
To comprehensively evaluate the mechanical properties of the quarry residuals with varying fine particle contents, thorough testing was carried out under both standard and modified compaction energies. The experiments encompassed soaked California Bearing Ratio (CBR), falling-head permeability, and direct shear box tests to assess the strength parameters of the materials. The CBR values obtained from the tests conducted under standard and modified compaction energies yielded notable differences for samples N1 and N2. Specifically, the samples prepared with modified energy exhibited significantly higher CBR values, registering at 45% for N1 and 67% for N2. These results underscore the influence of compaction energy on the strength characteristics of the materials. In accordance with the TSH, the CBR values obtained for sample N1 satisfied the requirement of CBR ≥ 20, rendering it suitable for use as upper base materials. Likewise, sample N2 fulfilled the criterion of CBR ≥ 50, signifying its potential application as lower sub-base materials. These findings highlight the appropriateness of these materials for specific engineering purposes based on their strength parameters. Analyzing the outcomes of the falling-head permeability tests conducted under modified compaction energy, it became evident that samples N1 and N2 exhibited different permeability coefficients. Sample N1 demonstrated a permeability coefficient of 1.2 x 10-6 m/s, while sample N2 exhibited a slightly higher value of 3.7 x 10-6 m/s. These results elucidate the role of compaction energy in influencing the permeability characteristics of the materials, with higher compaction energy correlating to decreased permeability. In addition, the direct shear box tests provided insights into the cohesive behavior of the materials. Both samples N1 and N2, prepared under standard compaction energy, displayed negligible cohesion values. These findings were confirmed for the samples prepared with modified compaction energy as well, suggesting that the cohesion values remained consistent regardless of the compaction method. Furthermore, the internal friction angles for samples N1 and N2 were determined to be 43° and 47°, respectively, based on the direct shear box test results. These results play a crucial role in understanding the shear behavior of the materials, which is vital in engineering applications. Overall, the experimental results revealed that an increase in compaction energy positively affected the strength parameters of both samples N1 and N2. This observation demonstrates the potential for improving the mechanical properties of the quarry residuals through appropriate compaction techniques, thereby enhancing their applicability in various engineering scenarios. With the objective of gaining a comprehensive understanding of the potential enhancement in the strength parameters of sample N2, various combinations of geofiber additives with different lengths and proportions were examined using unconfined compression tests. The samples were prepared under both standard and modified compaction energies to investigate the impact of these variables on the performance of the geofiber-reinforced materials. Upon analyzing the unconfined compression test results for the N2 samples compacted with standard energy, it was evident that the most favorable outcomes were achieved when utilizing a geofiber proportion of 0.1% combined with fiber lengths of 2 cm and 2.5 cm. These specific combinations demonstrated notable improvements in the strength properties of the material, indicating the potential effectiveness of geofiber additives in enhancing the mechanical characteristics of sample N2. Based on these encouraging findings, further investigations were conducted to evaluate the influence of geofiber additives on the unconfined compression strengths of sample N2 at different proportions and geofiber lengths. For this purpose, additional samples were prepared under both standard and modified compaction energies, incorporating various geofiber proportions and lengths. The analysis of the unconfined compressive strength of the N2 samples, taking into account the different geofiber lengths under standard and modified compaction energies, revealed that the most significant improvement was achieved when utilizing a 2.5 cm geofiber length under modified compaction energy. This combination resulted in enhanced strength parameters, indicating the potential for considerable improvement in the mechanical behavior of sample N2 through the appropriate use of geofiber additives. Furthermore, the investigation of the effect of geofiber proportion on the strength properties was examined separately for different compaction energies. Notably, it was observed that the optimal outcome was obtained with a geofiber proportion of 0.2% under standard compaction energy. Additionally, the highest unconfined compressive strength was attained when using a 2.5 cm sample with a 0.2% geofiber proportion under modified compaction energy. In conclusion, the interpretation of the unconfined compression test results highlights the critical importance of carefully considering the selection of geofiber length, proportion, and compaction energy to achieve optimal enhancement in the strength properties of sample N2. These findings underline the potential of geofiber additives as effective reinforcement materials and underscore the significance of comprehensive evaluations, considering various enhancement methods and cost considerations, to determine the most suitable and efficient utilization of geofiber additives in practical engineering applications.