An Experimental Study on the Effect of Micro-Metakaolin on the Strength and Swelling Characteristics of Expansive Soils

Expansive soils are found in many parts of the world, especially in arid areas and dry weather regions. Urbanization and development of new cities around the world resulted in construction in areas of challenging subsurface soil conditions. For example, in the Middle East, the Government of Egypt is building several new cities to accommodate the continuous increase in the country’s population. Most of these new cities are located in areas underlain by expansive soils. In this study, a series of laboratory tests were carried out to investigate the effect of introducing micro-metakaolin into the matrix of an expansive soil to improve the swelling potential as a new stabilizing material. Test results showed that micro-metakaolin can considerably decrease the free swell index of the soil by 37% and 54% at micro-metakaolin content of 15% and 25%, respectively. In addition, the shear strength of the soil was found to also increase as a result of the introduction of the micro-metakaolin material. Adding 25% micro-metakaolin content reduced the swelling pressure of the soil by about 33%. The results suggest that the proposed method is efficient in stabilizing and improving the properties of expansive soils found in arid areas. This is important to control excessive swelling and prevent possible damage to the supported structures.

Microbial-Facilitated Calcium Carbonate Precipitation as a Shallow Stabilization Alternative for Expansive Soil Treatment

Expansive soils generally recognized as swell-shrink soils have been a problem for civil infrastructure for a long time. Engineers are in search of sustainable stabilization alternatives to counter these problematic soils. Microbial-induced calcium carbonate precipitation (MICP) is a promising biocementation process that can improve the properties of expansive soil through calcium carbonate precipitation. Past research has shown promise for the use of MICP in mitigating swelling distress from expansive soils. In this research, MICP via biostimulation was attempted by mixing enrichment and cementation solutions with soils in an effort to develop a new alternative to shallow chemical stabilization. Three soils with varying clay contents (30%, 40%, and 70%) and plasticity characteristics were selected, and soils were treated by mixing with enrichment solutions followed by cementation solutions. Five different mellowing periods, three different curing periods, and two types of cementation solutions were studied to optimize the method. Treatment effectiveness was evaluated using unconfined compression tests, calcium carbonate tests, and free swell index tests. Results showed that an increase in the mellowing period beyond two days was not beneficial for any of the three soils tested in this research. It was determined that the best improvement was observed at two days of mellowing and seven days of curing.

Experimental Investigation on the Microstructural Properties of Black Cotton Soil Stabilized with Cinder (Scoria) Fines and Class-C Fly Ash

Black cotton soil is one of the significant problematic soil for any civil or geotechnical engineering application in the whole world. In the past several decades, different experimental studies have been carried out on the stabilization of expansive soil and different types of stabilizers like lime, Portland cement, cement fly ash, and lime fly ash were used and applied in highway and others construction. However, those traditional stabilizers are not environmentally friendly thus further scientific study is needed to minimize the percentage of carbon-based stabilizers. The fact that Ethiopia encountered major engineering problems due to these problematic soils many researchers have been conducted a vital study using traditional stabilizers for several years however there is no significant study on the microstructural properties of stabilized black cotton soil. In this study, a scoria fines and class c fly ash are used at different blended groups, for each group, the stabilizer content ranges from 10 to 30%. The liquid limit and plasticity index of the soil has been decreased with the increasing content of class c fly ash (FA) and cinder fines (CF). Especially after the soil treated with 25% of class c fly ash and 25% of cinder fines, the liquid limit has decreased by 51.61% and, the plasticity index by 78.61%, linear shrinkage by 66.58%, and the free swell index decreased by 78.9%. The CBR and UCS value has increased by 86.2% and 83.9%, respectively, and CBR swell reduced by 61.2% with increasing stabilizer content. The microstructural properties of Raw black cotton soil and samples that are selected based on strength and index properties (BCS+FA3, BCS+CF3, BCS+CF+FA3) were observed by Scanning electron microscopy (SEM) imagining device, and the result clearly shows the alteration in fabric and morphology of the sample. After treatment with class c fly ash and cinder fines, the laminated configuration of black cotton soil has changed to more flocculated and coherent mass. Also, the SEM image proves that cinder fines impart a mechanical bonding that forms well-developed floccules and a more porous nature. These types of particle arrangement and clay aggregation bring the improvement in index and strength properties.

EXPERIMENTAL STUDY OF STABILIZATION OF EXPANSIVE SOIL USING THE MIXTURE OF MARBLE DUST, RICE HUSK ASH AND CEMENT FOR SUB-GRADE ROAD CONSTRUCTION: A CASE STUDY OF WOLDIA TOWN

Understanding the behavior of expansive soil and adopting the appropriate control measures should be great for civil engineers. Extensive research has been going on to find the solutions associated with problems of expansive soils. There have been many methods available to control the expansiveness of these soils. The removal of expansive soils and replacement with suitable material has been widely practiced worldwide. Reasonable material is available within economic distances; however, suitable materials is not readily an available in urban areas for borrowing, which has to be hauled from a long distance. Instead of borrowing suitable soil from a long distance away, after stabilization with cost effective and readily available industrial and agricultural waste materials, it is economical to use locally available plastic soil. Such wastage products are also used to minimize environmental hazards such as CO2 in the atmosphere to minimize the percentage of industrial products used for stabilization, such as cement. Marble dust (MD), an industrial waste product, Rice husk ash (RHA), agricultural waste products, and cement are industrial products in this present study. The general objective of study was to examine the effects of poor subgrade soil stabilization using the mixture of MD, RHA and cement to enhance sub-standard soil engineering properties to be used as subgrade materials. Moisture content, Atterberg limits, grain size analysis, soil classification, free swell index, basic gravity, compaction (maximum dry density, optimum moisture content) and CBR value test have been calculated in this analysis. The design of the analysis followed by the experimental method of study were adopted, which started with sample selection. A disturbed samples was collected from the pit at a depth of 1.5 m to 2m from ground level in order to avoid the inclusion of organic matter by considering the free swell index value and observation was considered. The chemical analysis of MD and RHA was conducted in laboratory and the main oxides are (SiO2+Al2O3+Fe2O3) were 70.13% for RHA and 42.43% for MD. The RHA chemical properties satisfy the requirement, while MD did not meet the requirement of ASTM C 618. The Gomata Teachers’ Condominium (GTC) soil sample laboratory result have 42.72% plastic index (PI), 85% free swell index and its CBR value of 2.265%. The Millennium Secondary school (MSS) soil sample has a 48.79% PI, 87% free swell index and 2.121% CBR value. Therefore this soil samples are highly expansive were checked before any stabilizations process based on their plasticity index and CBR value based on standard specification requirement , then stabilization was achieved by stabilization by proposed (0,8MD,6MD+2C,4MD+4C,2MD+6C,8C,6MD+2RHA, 4MD+4RHA, 2MD+6RHA,8RHA,6RHA+2C,4RHA+4C,2RHA+6C,2MD+2RHA+4C,4MD+2RHA+2C, 2MD+4RHA+2C) proportion. Then LL, PI, OMC, and CBR decreased as the cement ratio increased, while PL, MDD and CBR value increases instead of MD and RHA increases, however, as MD and RHA increase, the quantity of cement decreases. The laboratory outcome was compared with the requirement of Ethiopian road authority standard, ASTM and AASHTO. Based on this study all mixing stabilizers (MD-cement, RHA-cement, MD-RHA, MD-RHA-cement) and 8% of RHA and cement fulfill the ERA standard specification requirements for its CBR swell value. However, 8% of marble dust alone does not fulfill the Ethiopia road authority requirements for CBR swell. The MD and RHA standalone does not improving some of the engineering properties of soil samples used for subgrade construction. However, they mixed with different percentages of cement can effectively stabilizer for this expansive soil for road sub-grade construction.

Experimental Investigations on Black Cotton Soil Stabilized with Sand and Cement

Has our Lands getting increasing of population and the reduction of available land, more and more construction of building sand other civil engineering structures has to be carried out on weak or soft soil. Owing to such soil of poor shear strength and high swelling & shrinkage, a great diversity of ground improvement techniques such as soil stabilization and reinforcement are employed to improve mechanical behavior ofsoil, thereby enhancing the reliability of construction. Black cotton soil is one of the major soil with this we are going to improve the soil by using sand and cement in deposits of India. The disappointments of asphalt in from of hurl dejection splitting and unevenness are brought about by the occasional dampness variety in subgrade soil. So, in this we using the various type of tests like plastic limit, liquid limit, California bearing ratio test, freewell index and specific gravity.Instead of cutting out and replacing the unstable soil,soil adjustment isthe only alternative asitsaveslot of time and ofmoneytoo.Theexhibithigh swelling and shrinking when exposed to changes in moisture content and hence have been found to be most troublesome from engineering considerations. Keyword: Black cotton soil, stabilization, CBR, sand and cement, sub- grade, Montmorinolite kaolinite, hydrated cations, Liquid Limit, Plastic Limit, Free swell index, Specific gravity.

Effect of Fly Ash and Cement on the Engineering Characteristic of Stabilized Subgrade Soil: An Experimental Study

The effectiveness of the use of waste fly ash (FA) and cement (OPC) in the stabilization of subgrade soils and the reasons likely to influence the degree of stabilization were investigated. Incorporating waste fly ash (FA) and cement (OPC) as additives leads to significant environmental and economic contributions to soil stabilization. This study involves laboratory tests to obtain the Atterberg limit, free swell index (FSI), the unconfined compressive strength (UCS), the California bearing ratio (CBR), and the scanning electron microscope (SEM). The test results for the subgrade soil illustrate that the Atterberg limit, plasticity index, and free swell index are decreasing with the addition of different proportions of fly ash and cement, i.e., 0%, 5%, 10%, 15%, and 20% and 0%, 2%, 4%, 6%, and 8%, respectively. The CBR value of untreated soil is 2.91%, while the best CBR value of fly ash and cement mixture treated soil is 10.12% (20% FA+8% OPC), which increases 71.34% from the initial value. The UCS of untreated soil is 86.88 kPa and treated soil with fly ash and cement attains a maximum value of 167.75 kPa (20% FA+8% OPC), i.e., increases by 48.20% from the initial value. The tests result show that the stability of a subgrade soil can be improved by adding fly ash and cement. While effectiveness and usability of waste FA and cement are cost-effective and environmentally friendly alternatives to expansive soil for pavement and any other foundation work in the future.

Determination of Geotechnical Properties and Stability of Expansive Soil using Fly Ash

This study was conducted to have a detailed analysis of the geotechnical properties of expansive soil and fly ash from Sipat thermal power plant. It reported the findings of laboratory studies on certain common physical and geotechnical properties. The chemical properties and morphology of the black cotton soil (BCS) and fly ash is also determined using scanning electron microscopy and X-ray diffraction test. The geotechnical test includes determining specific gravity, particle size distribution, moisture content, standard proctor test, free swell index, and Atterberg’s limit. The different compositions of expansive soil with fly ash, yellow soil, moorum, and sand are studied. BCS was evaluated with fly ash, fly ash and sand, BCS with yellow soil, and moorum and fly ash. The study also analyzed the details and results of different tests conducted on soil samples. The results showed that strength and fly ash are inversely proportional; as fly ash increases, strength decreases, and vice versa. Fly ash was added from 20 to 80 % by replacing expansive soil by weight. The results indicated that expansive soil can be stabilized by the addition of fly ash to a limit of 10 to 20 %. HIGHLIGHTS The XRD And SEM results shows the mineral present in the FlyAsh and Expansive soil The geotechnical properties of Flyash and expansive soil is determined The OMC increases with decrease in densities The Particle size distribution curve shows the soil is GW soil GRAPHICAL ABSTRACT

Mineralogical, Geochemical and Geotechnical Study of BCV 2017 Bentonite—The Initial State and the State following Thermal Treatment at 200 °C

Bentonites are considered to be the most suitable materials for the multibarrier system of high-level radioactive waste repositories. Since BCV bentonite has been proved to be an ideal representative of Czech Ca-Mg bentonites in this respect, it has been included in the Czech Radioactive Waste Repository Authority (SÚRAO) buffer and backfill R&D programme. Detailed knowledge of processes in the material induced by thermal loading provides invaluable assistance regarding the evolution of the material under repository conditions. Samples of both original BCV 2017 bentonite and the same material thermally treated at 200 °C were characterised by means of chemical analysis, powder X-ray diffraction, infrared spectroscopy, thermal analysis, cation exchange capacity, specific surface area (BET) measurements, the determination of the swell index, the liquid limit, the swelling pressure and water retention curves. The smectite in BCV 2017 bentonite comprises Ca-Mg montmorillonite with a significant degree of Fe3+ substitution in the octahedral sheet. Two main transformation processes were observed following heating at 200 °C over 27 months, the first of which comprised the dehydration of the montmorillonite and the subsequent reduction of the 001 basal distance from 14.5 Å (the original BCV 2017) to 9.8 Å, thus indicating the absence of water molecules in the interlayer space. The second concerned the dehydration and partial dehydroxylation of goethite. With the exception of the dehydration of the interlayer space, the PXRD and FTIR study revealed the crystallochemical stability of the montmorillonite in BCV 2017 bentonite under the selected experimental conditions. The geotechnical tests indicated no major changes in the mechanical properties of the thermally treated BCV 2017 bentonite, as demonstrated by the similar swelling pressure values. However, the variation in the swell index and the gradual increase in the liquid limit with the wetting time indicated a lower hydration rate. The retention curves consistently showed the lower retention capacity of the thermally treated samples, thus indicating the incomplete re-hydration of the thermally treated BCV 2017 exposed to air humidity and the difference in its behaviour compared to the material exposed to liquid water.

Impact of Multi-Branched Ionic Liquid on Shale Swelling and Hydration for High Temperature Drilling Applications

Shale swelling and hydration during the drilling operation have adverse effects on the stability of a wellbore. Hydrophilic interactions of shale results in swelling and disintegration of the shale formation. This paper discusses wettability changes and hydration characteristics of shale to improve the wellbore stability. The use of multibranched ionic liquid as drilling fluid for high temperature applications was investigated. The novel multibranched ionic liquid (Trihexyltetradecyl phosphonium bis (2,4,4-trimethyl pentyl) phosphinate, denoted as Tpb-P) water-based drilling fluid was prepared by mixing different concentrations of ionic liquid and other additives such as filtration controller, rheological modifier, and pH controller. The wettability of bentonite powder was determined using a contact angle in the presence of various concentrations of ionic liquids. Several other experimental techniques, such as linear swelling, hot rolling recovery, and bentonite swell index, were used to examine the inhibition performance of ionic liquid. The rheology and filtration properties of ionic liquid-based drilling fluid were also examined. Various concentrations of multibranched ionic liquid were used to formulate the drilling fluids ranging from (0.1 to 0.5 wt.%), and their performances were compared with the base drilling fluid prepared without ionic liquid. The hydrophobicity of the shale surface was determined by measuring the contact angle, and results showed that drilling fluid having 0.1 wt.% concentration of ionic liquid has a maximum contact angle indicating the highly hydrophobic shale surface. The hot rolling shale recovery experiment was conducted at 150°F, and it was observed that adding ionic liquid improved the shale recovery (24.4%) compared to the base fluid recovery (12.8%). The linear swelling was evaluated over the time of 24 hours, and the least swelling of bentonite was noticed with 0.1 wt.% ionic liquid (98.1%) compared to linear swelling in deionized water (125%). The results suggested that the ionic liquid in the drilling fluid chemically interacted with the clay surface and reduced the hydrophilicity of clay, which restricts the exchange of water onto the clay surface.

Effect of chemical stabilisation on index and engineering properties of a remoulded expansive soil

This note presents the effect of lime, cement, fly ash and ground granulated blast furnace slag (GGBS) on free swell index (FSI), liquid limit (LL), plasticity index (PI), compaction characteristics, hydraulic conductivity (k) and strength characteristics of an expansive soil. The effect of the above chemicals on California bearing ratio (CBR) was also presented. Lime content was varied as 0%, 1%, 2%, 4% and 6% and the amounts of other additives were varied as 0%, 5%, 10%, 15% and 20% by dry weight of the soil. FSI, LL and PI decreased significantly with increasing additive contents. Compaction characteristics also improved with increasing additive contents. Strength characteristics showed improvement at higher additive contents especially at higher curing periods. CBR (determined in soaked condition) also increased significantly with increasing additive contents.