Settlement Analysis of a Sandy Clay Soil Reinforced with Stone Columns

Mahdi

et al. 2023

Self Cite

Nowadays, the use of recycled waste materials in road pavement is regarded not only as a positive option in terms of sustainability but also as an appealing option in terms of providing improved service performance. The current study aimed at evaluating the performance of crumb rubber and polyethylene terephthalate plastic polymer in asphalt mixture in modifying the mechanical properties of asphalt pavement. Experimental tests were carried out both for asphalt binder and asphalt mixture. Different proportions of mix for crumb rubber and polyethylene terephthalate plastic polymer were used to systematically investigate the effect of mix ratio on performance of the asphalt material. The experimental analysis reveals that the combined application of 10% by weight of crumb rubber chips and 2% polyethylene terephthalate plastic polymer are the ideal mix ratios found effective in modifying properties of the asphalt mixture. The asphalt binder test results indicate that adding 10% crumb rubber to asphalt binder reduced penetration by 1.56% along with increment of the softening point by 4.33%. Furthermore, the indicated optimum mix amount resulted in 0.17% rise, 20.07% drop, and 20.71% increase in Marshal stability, flow, and stiffness, respectively. Besides, tensile strength of the asphalt mixture was enhanced with addition of the filler and binder materials. It was witnessed that the combined application of the additives performs better than their separate use in modifying properties of the asphalt mix.

Section: Materials Usedmentioning

confidence: 99%

Combined Performance of Polyethylene Terephthalate Waste Plastic Polymer and Crumb Rubber in Modifying Properties of Hot Mix Asphalt

Alemu

Mahdi

et al. 2023

Self Cite

“…Upon placement of external loading, the excess pore pressure begins to rise which is a typical characteristic of clayey foundations [2]. Clay soil is typically known for its poor workability, in which embankment loads result in bearing failure and excessive deformation after construction [3]. In many practical cases, the removal of massive clay deposits down to larger depths is technically and economically not feasible.…”

Section: Introductionmentioning

confidence: 99%

Consolidation Attributes and Deformation Response of Soft Clay Reinforced with Vertical Scoria Drains under Road Embankment

Gebretsadik

Negesa

2023

Self Cite

Application of vertical drains in soft clay soils is a common practice widely known to facilitate the consolidation rate. To overcome the adverse impact of a long-lasting consolidation process, highly permeable materials such as sand and crushed aggregates are used as drains. However, limited information exists regarding the applicability of scoria gravel as a vertical drain that no concisely documented information is observed in the literature. This study hence aimed at investigating suitability of scoria as a vertical drain in perpetuating the consolidation process of soft clay under highway embankment. Finite element-based numerical simulation was used to model the drain. The model was carried out by using 3D version of Plaxis software. In order to incorporate the effect of gradual load increment on the consolidation rate, the staged construction approach was employed. Both the square and triangular installation patterns were considered in the model in order to explore the critical effects of the drain installation pattern on the rate of consolidation. The numerical analysis also included varying dimensions of the vertical drain so as to investigate the effects of the dimension parameters of the vertically installed scoria drains. The conducted numerical analysis revealed that the rate of consolidation was considerably accelerated with provision of a group of scoria drains. With increase in the diameter of the drain, the consolidation rate increases, whereas the consolidation rate is inversely related to increase in drain spacing. For the drain installed at a spacing of 2 m, a diameter of 0.4 m, and a length of 8 m any arbitrary settlement magnitude is achieved 25 days earlier than the case without drains. Besides, incorporation of scoria drains lessens the pore pressure developed. The comparative analysis conducted on the effect of drain arrangement revealed that no considerable difference was witnessed in the performance of the square and triangular installation patterns even though the consolidation rate remains slightly faster in the case of the triangular installation pattern.

Evaluating the Effectiveness of Nonwoven Geotextile-Encased Cinder Gravel Column in Improving Load-Bearing and Deformation Characteristics of Soft Clay

Tefera

Bafena

et al. 2023

Self Cite

Application of vertically installed columnar materials made of natural gravels or crushed aggregate is one of the commonly implemented practices to improve the performance of soft clay grounds under footing load. Alternative materials like cinder gravel also plays a reinforcing role when blended with soft clay. However, information on the precise extent to which a vertically installed cinder gravel column is effective in improving the properties of a clay foundation and its potential response to the permanently applied footing load has not been well documented in the literature. Hence, the current study specifically aimed at evaluating the effectiveness of geotextile-encased cinder gravel column in improving deformation and bearing capacity of soft clay ground. The experimental model which considered installation of a single geotextile-encased cinder gravel column into soft clay was considered. A cylindrical steel container was used in designing the experimental test. The container was filled with clay soil and the cinder gravel column was vertically installed through a replacement method. Finding of the study revealed that ultimate load-bearing capacity of the soft clay foundation after being reinforced with conventional cinder gravel was 1.85 times that of the untreated soft clay soil. The load-carrying capacity of the clay soil decreased with increment in diameter of the column whereas it is directly related to the volume replacement ratio. With regard to directional improvement, the vertical reinforcement performs better than the horizontal geotextile strips in cinder gravel column from bearing capacity improvement view point. In lessening settlement, however, application of horizontal geotextile discs at spacing ranging between half- and full-column diameter overweighs performance of the vertical encasement. In summary, application of geotextile encasement to the top 75% of the clay thickness is sufficient to come up with optimum improvement in bearing capacity and encasing the entire thickness is not necessarily required.