High Expansive Soil Research Articles

Stablisation of Expansive Soils by Fly-ash & Wool Waste

In the current study, an effort has been made to stabilise the local expansionary soils using the appropriate mix of locally accessible industrial waste with or without lime. In this study, a sample of high expansive soils was employed taken from Rajpura (PB) and a sample of low expansion soils. Industrial waste like fly ash and wool from local businesses are utilised as additions to stabilise soil both. Fly ash and wool waste are individually added to soils with varying quantities (from 5 to 30 percent) and the weight of a dry soil blend increases by 5 percent. The geotechnical qualities of solar mixes are examined by a range of experiments such as CBR, unconfined compression, triaxial compression and consolidation tests. After 9 days of water treatment, the uncontained compression and triaxial compressive tests are performed on the soil-fly ash and soil-wool waste samples. The samples of soil-fly ash and soil-wool waste are shown to reduce the plasticity, swelling and compressibility by increasing additives and increasing matching CBR, shear strength and permeability.

Shrinkage Parameters of Modified Compacted Clayey Soil for Sustainable Earthworks

The shrinkage limit is one of the Atterberg limits and is a fundamental geotechnical parameter used to assess the settlement and other volume change parameters of engineering soils containing clays. This paper describes shrinkage limits and index tests results on expansive soil treated with rice husk ash (RHA) and 5%, 10% and 15% quicklime activated rice husk ash (QARHA) obtained using laboratory testing procedure. The representative soil was subjected to classification tests and it was found to be high expansive soil, an A-7-6 soil according to American Association of States Highway and Transportation Officials (AASHTO) and poorly graded according to Universal Soil Classification System (USCS). It was classified as highly plastic soil. The soil was subjected to treatment exercise at the rate of 0% (reference), 2%, 4%, 6%, 8% and 10% addition of RHA, 5%-QARHA, 10%-QARHA and 15%-QARHA by weight of dry soil. The RHA addition improved the shrinkage properties; shrinkage limit at varying rates ranging from 5.7%, to 27.9% for 2%, and 10% RHA addition respectively with reference to the control experiment. And for the shrinkage index, the improvement rate was also substantial i.e. 7.8% to 55.7% at 2% and 10% RHA addition respectively with reference to the control experiment. The effect of rice husk ash activated with 5% quicklime lime (5%-QARHA) showed improvement rate of 6.6% and 34.4% at 2% and 10% 5%-QARHA addition respectively with reference to the control experiment. Also, the effect of rice husk ash activated by 10% and 15% quicklime (10%-QARHA and 15%-QARHA) on the shrinkage properties was presented with the rates of improvement which shows that the higher the rate of activation of rice husk ash with quicklime, the higher the pozzolanic performance Finally, rice husk ash and its composites achieved by quicklime activation process have shown to be alternative cementing materials for use as binders in the modification of expansive soils utilized as subgrade materials.

Using Fine Silica Sand and Granite Powder Waste to Control Free Swelling Behavior of High Expansive Soil

Many researchers have been interested in studying the effect of adding local natural materials or construction waste on the properties of poor subgrade soil. However, changes in size and strength of expansive soils can cause extensive damage to the geotechnical infrastructure. This damage is often repeatable and latent in the long term, and is a critical issue in highway subgrade engineering. This paper examines the effect of adding both Fine Silica Sand (FSS) and Granite Cutting Powder Waste (GPW) materials on the welling characteristics of expansive soils. Atterberg limits, free swell index, and rate of swell of the mixtures were used as a key to assess properties of a group of expansive soil samples after adding different percentages of the mentioned materials. The rates of additions were 10%, 20%, 30%, 40%, 50%, 60 and 70% of the weight of the soil samples. The test results showed that FSS and GPW significantly affect the expansive soil properties. However, adding 70% of both FSS and GPW reduced the swelling index from 58.3% to 6.6% and from 58.3% to 11% after 7 days of curing, respectively. This study suggests that the Fine Silica Sand and Granite Powder Waste can be used as stabilizers for expansive highly plastic soils.

VOLUME CHANGE AND COMPRESSIVE STRENGTH OF COMPACTED LATERITIC SOIL UNDER DRYING-WETTING CYCLE REPETITION

This study was conducted to investigate volume changes and compressive strength behavior of compacted high expansive soils from lateritic soils (60%) and bentonite (40%) mixture under drying-wetting cycle repetition as a construction materials alternatives. Lateritic soil obtained from waste Nickel mining site in East Halmahera, North Maluku, Indonesia. Laboratory tests of physical properties using ASTM standard test were conducted to lateritic soil, bentonite, and mixture soil, while SEM test for lateritic and mixture soil. The soil samples have optimum moisture content based on Proctor standard compaction test results (28%). Then, samples were treated drying-wetting cycle and repeating four cycles with 25, 50, 75, and 100% series path. The soil suction measurement used the Whatman #42 filter paper placed at the top, middle, and bottom of each sample, and after that, the unconfined compression strength test was performed based on the ASTM standard. The experimental results showed that the drying-wetting cycle repetition has a significant effect on volume change, suction, and compressive strength of the soil. The increasing number of cycle causing void ratio decrease and degree of saturation increase, and soil suction tend to decrease at the certain void ratio; likewise, soil compressive strength decreases at particular water content. Decreasing soil compressive strength causes a decrease in elastic modulus so that soil failure behavior is more brittle and work-softening. Therefore, the study results provide important geotechnical characteristics data of lateritic soil with high swell-shrink potential. Henceforth, some soil improvement innovations can perform to generate high-quality construction materials more effectively and efficiently.

Influence of Energy on Compaction Characteristics of High Expansive Soils

Each soil type has different behavior with regard to determination of maximum dry density and optimum moisture content and therefore any soil type has its own compaction requirements for experimental purposes and for control the compaction in the field. The general purpose of this study is to a better understanding of the compaction characteristics of high expansive soils, with emphasis on the relationships of moisture content and dry density of high expansive soils at a range of compaction energy levels. To achieve this purpose, high expansive soils samples were subjected to Atterberg limit and a set of laboratory compaction tests to find compaction characteristics namely; maximum dry unit weight and optimum water content of high expansive soils at different compaction energy (compaction effort) for different number of hammer blows per each layer range from 10 to 50, which varied the energy per unit volume from 356 KN/m3 to 1188 KN/m3.Rather than single peak compaction curves, the most achieved compaction curves are an irregular one and half peak compaction curves. According to the comparison results of different compaction energy, it was concluded that the maximum dry unit weight of high expansive soil was not highly affected by gradually increase of applied energy. The results showed that, the maximum dry density of tested expansive soils sample increased from 1.48g/cm3 to 1.6g/cm3 with increase of compaction energy from 356 KN/m3 to 1188 KN/m3.

GIS as A Tool for Expansive Soil Detection at Sulaymaniyah City

Geotechnical engineering like any other engineering field has to develop and cope with new technologies. This article intends to investigate the spatial relationships between soil’s liquid limit (LL), plasticity index (PI) and Liquidity index (LI) for particular zones of Sulaymaniyah City. The main objective is to study the ability to produce digital soil maps for the study area and determine regions of high expansive soil. Inverse Distance Weighting (IDW) interpolation tool within the GIS (Geographic Information System) program was used to produce the maps. Data from 592 boreholes for LL and PI and 245 boreholes for LI were used for this study. Layers were allocated into three depth ranges (1 to 2, 2 to 4 and 4 to 6) m. A total of 1396 observations were used for producing the maps for both LL and PI, and 371 data for LI. Based on the results, the IDW method gives reasonable predictions depending on the results of R2 and RMSE. The results also showed that the study area has relatively large zones of high expansive soil that must be taken into considerations before performing any construction activity. These maps are essential for helping geotechnical engineers in making decisions and visualizing soils’ behaviors.

Stabilization of highly expansive soils containing sulfate using metakaolin and fly ash based geopolymer modified with lime and gypsum

Abstract High sulfate expansive soils present special challenges during stabilization. Traditional stabilizers such as lime and cement which are rich in calcium are ineffective in controlling shrink/swell behavior of these soils due to formation of the expansive mineral, ettringite. In this study, two geopolymers synthesized from aluminosilicate sources, fly ash and metakaolin, were investigated to determine their effectiveness in stabilizing shrink-swell behavior of high sulfate expansive soil. Geopolymers were modified with lime and gypsum to improve their efficacy as stabilization agents for sulfate bearing soil. Modifier contents were optimized to achieve maximum reduction in swell potential and at the same time prevent ettringite formation. Microstructural analyses were performed on lime and gypsum added geopolymer to determine the mechanism of modification. Swell tests were conducted on high sulfate soil treated with modified geopolymer at different concentrations and optimum concentration of modified geopolymer required to achieve minimum swell was established.

Load sharing and behavior of single pile embedded in unsaturated swelling soil

This study presents a series of model experiments conducted on single pile embedded in saturated and unsaturated expansive soil. A soil composed of 70% bentonite and 30% sand which represents a very high expansive soil is employed in this study. Soil suction (total and matric) was measured using the filter paper technique and calibrated electrical resistance gauges to study the behavior of the soil water retention curve (SWRC) and initial suction and their influence on the results. The results showed that the ultimate skin resistance is increased about 49% when the initial degree of saturation decreases from 90 to 70%. However, the adhesion factor (α, used in calculating the skin friction) increases as the unconsolidated undrained cohesion decreases and as the initial matric suction decreases. The adhesion factor reached a value of 1.3 when the undrained cohesion is 36 kPa, initial degree of saturation of 100% and initial matric suction of 10 kPa. The sharing ratio of the ultimate shaft capacity to the ultimate pile capacity of a single pile changes from 91 to 81% when the degree of saturation decreases from 100 to 70%.

The impact of natural ornamental limestone dust on swelling characteristics of high expansive soils

Expansive soils are considered as a potential natural hazard if they are not adequately treated. Expansive soils have high potential for shrinking and swelling under changing moisture conditions and cause extensive damages to engineering infrastructures. This study is concerned with the suitability of natural ornamental limestone dust to reduce the swelling characteristics of high expansive soils. The results are revealed that the swelling pressure and percent of heave are greatly decreased with increasing the inserted core diameters and mixing percentages of limestone dust. The average reduction percent values of swelling pressure and percent of heave are increased from 2.21% to 43.09% and from 2.56% to 45.64%, respectively, for treated soil samples with increase in limestone dust core diameters from 5 mm to 20 mm (1% to 16% of total soil area). The average reduction percent values of swelling pressure and heave percent are increased from 10.29% to 70.73% and from 22.29% to 82.90%, respectively, for treated soil samples with increase in limestone dust mixing percentages from 10% to 30%. The results are revealed that the enhancement in swelling characteristics of high expansive soils that are treated by ornamental limestone dust is mostly attributed to the replacement of high expansive fine clay particles by non-expansive and non-plastic coarse limestone dust particles, and to the presence of a considerable amount of free lime in limestone dust (4.97% as [Ca(OH)2]) that is responsible for converting the high expansive soils to less expansive soils by pozzolanic reaction. The mixing treatment method is more suitable for surficial and shallow foundation high expansive soil beds, while the compacted limestone dust piles “inserted limestone dust core method” are more suitable for deep foundation high expansive soil beds.

Volumetric Shrinkage Strain Measurements in Expansive Soils Using Digital Imaging Technology

Abstract Expansive soils undergo large volumetric shrinkage strains, which eventually lead to high heave movements upon hydration of these soils. Current test methods to determine shrinkage strain potentials of soils are restricted by several limitations including small specimen sizes, molds with rigid walls that restrain shrinkage strains in lateral directions, and manual measurement errors. In this paper, a novel methodology to conduct volumetric shrinkage strain test on cylindrical soil specimens and a digital imaging technique to analyze and determine volumetric shrinkage strains of the test are described. As part of the evaluations of this methodology, volumetric shrinkage strains of four types of medium to high expansive soils were researched. Shrinkage tests were conducted on all four soils at three different moisture contents. Volumetric shrinkage strains were then measured using both digital and conventional manual approaches. Test results showed that the test and the developed measurement methodology provided repeatable and realistic shrinkage strain measurements. Digital measurements provided more accurate results than manual measurements by accounting for even minor shrinkage cracks in the soils. The significance of the digital measurements in relation to the current shrinkage strain characterizations is discussed. Potential geotechnical application areas where these test results could be used are also described.