Experimental Performance Studies on the Improved Expansive Subgrade Soil Formation by Using Mechanical Stabilization with Natural Gravel Around Jimma Quarry Sites

Abstract

Expansive soil refers to a particular type of soils -almost clayey soils in property -that expand as they absorb water and shrink when they dry out. The process of swelling generates pressures that can cause lifting, or heaving of structures whilst shrinkage process can cause differential settlement on civil structure. A large number of buildings and roads are placed on such type of soil and exposed to the danger from this swelling and shrinkage processes. In order to avoid the previous mentioned risk from the expansive soil, a technique of soil stabilization should be made for this type of soil to enhance some of its properties. In this study, the experimental investigations have been made to study the suitability of natural gravel from jiren quarry site to improve properties of expansive soil. The important parameters to be determine the geo-technical properties such as Specific gravity, Liquid limit, Plastic limit, Plasticity index, dry density and California Bearing (CBR) ratio values. According to ERA 2002 this type of soils is poor for subgrade for road construction. In order to realize the desired objective, a purposive sampling technique which is non -probability method was adopted in order to collect disturbed soil samples at depth of 1.5m and natural gravel from jiren quarry site used for the preparation of different laboratory tests. The laboratory work involved sieve analysis along with consistence test to classify the soil sample. The preliminary investigation of the soil shows that it belongs to A-7-5 class of soil in AASHTO and CH in USCS soil classification system. Soils under this class are generally of poor for subgrade road construction. Atterberg limits, compaction and CBR tests were used to evaluate properties of stabilized soil. The soil was stabilized with natural gravel in stepped concentration of 5%, 10%, 15%, 20% and 25% by dry weight of the soil. Analysis of the results shows the addition of natural gravel improve the geotechnical properties of the expansive black cotton soil. The addition of natural gravel reduces plasticity index, swelling and OMC with an increase in MDD and CBR with all increased natural gravel contents. The addition of 20% and 25% of natural gravel established an increased CBR value by 670% and 958% respectively, indicating the subgrade class falling under S4 and S5 respectively. From this study it was found out that natural gravel stabilized with soil do meet the minimum requirement of ERA pavement manual specification for use as a sub-grade material in road construction.

Investigating Causes of Flexible Pavement Failure: A Case Study of the Bako to Nekemte Road, Oromia, Ethiopia

“…𝑚 𝑖=1 ai)+PCIa(∑ A 𝑚 𝑖=1 ai) A (4) Where: PCIa = area-weighted PCI of additional sample units, PCIr = area-weighted PCI of randomly surveyed sample units Aai = area of additional sample unit i, A = area of the section, m = number of additional sample units surveyed, and PCIs = area-weighted PCI of the pavement section.…”

“…Maintenance and repair expenditures can easily exceed the cost of the road itself, putting a financial strain on developing countries. In most cases, these damages result in economic losses for the entire country [4][5][6]. Inadequate drainage, a lack of acceptable pavement design, and an excessive amount of water in the sub-grade contribute to sub-grade failure, poor subgrade soil, and a lack of normal maintenance by the responsible body [7,8].…”

A study on the applicability of scoria gravel an alternative base course material through blending with marble waste aggregate

“…Through connections with airports, railway stations, and ports, roads play an essential part in the development of intermodal transportation. Road construction is a crucial concern in civil engineering practice for any country's to initiate a rapid industrial development, increases socio-economic intractions [ 1 , 2 , 3 ]. This is because transportation infrastructures allow people and supplies to move quickly and easily from one location to another at required time, enhancing social mutual interaction.…”

Potential Use of 'Enset' Fiber Ash as Partial Replacement of Conventional Filler Material in Hot Mix Asphalt

“…In Ethiopian road construction and maintenance work require a huge amount of high-quality materials due to the rapid growth of uncontrolled heavy traffic axle load necessitate a higher quality of paving materials during the construction of pavement [1]. The improvement of construction materials which was locally available material, by using stabilizing techniques to improve the engineering property that satisfies the standard specification to attain the intended purpose for road construction [2][3][4][5][6]. There are currently different Bitumen modification strategies utilized to improve the performance, reducing thermal susceptibility and enhanced rutting and fatigue resistance.…”