ANALYSIS OF LATERITE SOIL WITH PORTLAND CEMENT MIXED VARIATIONS AND THE EFFECT ON THE CBR UNSOAKED

Ketapang and Kayong Utara Regency have road construction that often suffers damage before the planned life age caused by the behavior of expansive clay. The subgrade is a fundamental structure in building road construction because the subgrade will support traffic loads or construction loads. The strength and durability of the pavement structure road will depend on the properties and bearing capacity of the subgrade. Practically soil stabilization is a reinforcement engineering against foundation or subgrade by using mixed materials. Therefore, different soil improvement variations are needed. Based on the test result, the CBR value of Sukadana initially gets a 2.95% point. The CBR value for the 6% and 10 % mixture, respectively, gets 17.14% and 25.02%. The CBR value of Sungai Melayu Rayak originally get 4.65% point. Then, for the 6% and 10% mixture, the CBR values increased by 13.78% and 18%. The value of the bearing capacity of the highway soil construction can be know from the results of CBR testing on each variation. The CBR also can measure the strength of the soil. The addition of cement to the earth tends to increase the bearing capacity of the ground. It is because cement can function as a binder between soil particles with chemical compounds contained in cement.

Analysis of soil characteristics on expansive clay stabilization using shell ash

Expansive clay is one of the problems in construction work. The soil has the characteristics of being easy to expand when exposed to water, causing a decrease in the strength value of the soil. The can be overcome by stabilizing the soil. The soil is formed from weathering and contains the mineral montmorillonite. The soil is very sensitive to moisture content, has a high shrinkage rate, thus interfering in construction work. Therefore, additional materials are needed to overcome the problem, one of which is soil stabilization. The study aimed to stabilize the expansive clay soil. This is done by analyzing the physical and mechanical properties of expansive clay with a shell ash mixture. Expansive clay is taken directly (undisturbed) or disturbed. Undisturbed soil is taken using a tube, so that the soil is not disturbed by outside air, while disturbed soil is taken using a shovel and then put into a sack container. Expansive clay stabilization method lies in adding the percentage of shell ash mixture (5 %, 10 %, 15 %, and 20 %). The soil, the initial moisture content (γd) of which has been determined, is mixed, then molded into a cylindrical shape. The mold was stored in a desiccator, then watered with 5 % water every day until the soil became saturated. Then, using a Proctor test, chemical tests (soil chemical test, soil mineral test), physical tests (soil moisture, Atterberg limit), and mechanical tests (unconfined compression test, compaction test, swelling test) were carried out. The results showed that the addition of an oyster shell ash stabilizing agent to expansive clay affected the physical and mechanical properties of the soil. The addition of shell ash can reduce soil moisture with various plasticity indexes. While the soil stress value decreased, the swelling of the soil increased significantly above the original soil.

Evaluation of the Curing Time Effect on the Swelling, Unconfined Strength and Resilient Modulus of an Expansive Soil Improved with Hydrated Lime

Soils with high plasticity and high swell potential undergo great volume changes in the presence of unstable water content changes. The resulting expansion leads to damage to pavements and/or lightweight structures with such a subsoil. Expansive soils can be improved by adding chemical stabilizers such as lime, fly ash and micro cement. To construct a highway on an expansive subgrade soil, the subgrade should be stabilized to satisfy the minimum requirements of the highway standards. In this research, expansive clay samples were collected from clay deposits in the Akyurt district of Ankara (Turkey), near Esenboğa Airport. The swelling, strength and resilient modulus properties of the soil samples were determined via laboratory tests. First, reference tests were carried out on natural soil samples. Then, the clay samples were mixed with lime agent at different percentages (1%, 3%, 5%, 7% and 9%) according to the dry weight of the soil. The index, swelling, strength and resilient modulus (Mr) properties of these samples were determined. The soil samples were tested at 7, 28, 56 and 90-day curing times for each percentage of lime agent considered. The changes in the abovementioned properties, especially with regard to the effect of curing time on improvement, were interpreted in this research. Designing for a 7% lime content and a 28-day curing time can be a sound solution for addressing the expansive clay studied in this research, since the criteria of the Turkish Highway Standards are satisfied under these conditions.

Blending Lime with Sugarcane Bagasse Ash for Stabilizing Expansive Clay Soils in Subgrade

Expansive soils constitute one of the most frequently encountered and challenging soils to geotechnical engineers. This study assessed the possibility of utilizing sugarcane bagasse ash (SCBA) by partially replacing slaked lime to stabilize expansive clay soils. The soil samples were picked from Muduuma area, Mpigi district, Central Uganda. Experimental tests of linear shrinkage (LS), plasticity index (PI), and California Bearing Ratio (CBR) were conducted on both unstabilized soil and SCBA-lime treated samples. The SCBA-lime mixture was prepared by partially replacing 5% lime with SCBA at 2, 4, 6, 8, and 10% by weight. Hence, SCBA was used in proportions of 0.1, 0.2, 0.3, 0.4, and 0.5% by dry weight of the soil. The addition of lime greatly lowered the PI and LS, which later increased with the addition of the SCBA. The maximum dry density was generally lowered with the addition of lime and SCBA, from 1.87 g/cm3 to 1.58%. The CBR increased with SCBA-lime addition from 12% for unstabilized soil up to 48% at 6% SCBA replacement. The optimum lime replacement was established as 6% SCBA lime replacement based on CBR criteria. At the 6% optimum, the optimum moisture content (OMC) was 1.7 Mg/m3, LS was 10%, and PI was 20%. This study demonstrated the potentiality of SCBA as a novel construction material, specifically by partially reducing the usage of the unsustainable, non-environmentally friendly lime. It is also expected to enable using currently unsuitable clays from the region.

Effect of Sand and Sand-Lime Piles on the Behavior of Expansive Clay Soil

Expansive clay soil causes serious problems to many structures due to its swelling and shrinkage during wet and dry seasons. With the existence of expansive soil in Ahkmim new city, Sohag governorate, Egypt, some light buildings, road pavements, and buried pipelines have shown some damage. To avoid such damage, prior to construction, expansive clay soils should be stabilized. Different methods are available to improve the engineering properties of these soils such as densification, chemical stabilization, reinforcement, and techniques of pore water pressure reduction. The chemical stabilization of clay using lime is one of the widespread methods that can be used to improve the behavior of expansive clay soil. This study aims to investigate the effect of both sand and sand-lime piles on the behavior of expansive clay soil. A series of laboratory tests were carried out using the conventional Oedometer apparatus. Sand piles with different replacement area ratios (RARs) (4.68%, 10.16%, 24.6%, 35.84%, and 56.9%) were used. Also, sand piles stabilized with different percentages of lime (3%, 6%, 9%, 12%, 15%, and 20%) and with a replacement area ratio of 35.84% were used. The experimental results showed there is a significant improvement in reducing the swelling potential of expansive clay soil reinforced with sand or sand-lime piles. This improvement increases with the increase of both replacement area ratio and lime content.

Analysis of shear strength of the expansive soil stabilized with kaolin at various soaking times

Expansive clay soils are high shrinkage soils that have low bearing capacity. So an effort is needed to reduce the nature of its swelling. One effort that can be done is the method of soil stabilization, where the soil is mixed with materials that can reduce soil swelling and increase the shear strength of the soil. One of the materials that can be used is kaolin powder. Kaolin is a stabilizing agent found in nature so it is easy to obtain. The purpose of this research is to analyse the decrease of expansive soil swelling and the value of its unconfined compression strength at various soaking times. The test was carried out by mixing 9% kaolin powder against dry soil weight. The stabilized soils were then compacted as samples to be soaked with time variations of 0 days, 3 days, 7 days, 10 days, and 14 days. The results of the test after soaking 14 days is a decrease of the stabilized soil swelling value up to 67.78%. The unconfined compression strength is increase up to 77.28% compared to its natural condition.