Remediation of Clayey Soil Using Silica Fume

Predicting soaked CBR of SC subgrade from dry density for light and heavy compaction

This review paper presents the current research state of the relationship between geotechnical soil properties and the California bearing ratio (CBR) value. Geotechnical considerations are pivotal in civil engineering projects to prevent collapse and settlement failures, underscoring the importance of understanding detailed soil properties. A CBR test used for assessing stiffness modulus and shear strength guides the overlaying layer-thickness calculation during pavement design. Although expensive and complex, researchers have explored correlations and machine-learning algorithms for CBR prediction from soil properties. This study delves into the varying influence of properties such as compaction (optimum moisture content and maximum dry density) and index (liquid, plastic, and shrinkage limits) properties. The relevance of such properties to CBR is explored, examining their significance and potential interactions. This review highlights the multi-faceted effects of soil properties on CBRvalue, enabling informed pavement engineering decisions.

Some clay soils classified as extended soils threaten the structures resting on them. Many additives are available to improve the properties of expanded soils. This study tries to investigate the consequences of wetting-drying cycles on the swelling behavior of modified expansive clayey soils under laboratory conditions by modifying expansive clayey soil samples using emulsified asphalt. Five different percentages of emulsified asphalt were used: (2, 4, 6, 8, and 10) %. The natural and treatment soils were tested for classification, specific gravity, compaction characteristics, free swell and swell pressure, consolidation, and compressive strength. The liquid limit and plasticity index have been lowered by adding Emulsified Asphalt. After that, the effects of Emulsified Asphalt on undrained shear strength characteristics (cohesion and friction angle) have been studied. The results revealed that when the emulsified asphalt content was increased to 10%, the swelling pressure and swelling potential decreased by 58 and 78 %, respectively. The swell and shrink improvement factor for the 10% emulsified asphalt addition is always larger than 75%. As the duration of wetting-drying cycles increased, the swelling pressure and swelling potential values were also reduced. The plastic limit, on the other hand, increased as the Emulsified Asphalt content increased. Increasing the amount of Emulsified Asphalt increased the maximum dry unit weight values, whereas the optimum water contents increased. It was concluded that emulsified asphalt stabilization may be useful for expansive clay as it improves compressive shear strength.

Among the different layers of the pavement, subgrade is the bottom most layer, and this layer plays a very important role in the design of pavements. However proper characterization of the said layer involves different types of test data like maximum dry density (MDD), optimum moisture content (OMC), plasticity index, and California bearing ratio (CBR). Among which, CBR is the most important parameter used effectively for assessment of the strength parameter of the subgrade soil. For proper characterization of the subgrade, a large number of CBR tests are required. The CBR tests are elaborative, costly and also time consuming which may delay the progress of constructional activity of the road. In such situation, the value of soaked CBR may be predicted with the help of artificial neural network (ANN), which may help to run the project smoothly. The word “network” in ANN refers to the interconnections between the neurons in the different layers of each system. Those preliminary testing data i.e. percent fines, MDD, OMC, LL, PL, PI etc., are required to find out the regression value and mean square error of the training, validation, and test data to create a model by using neural network algorithm. The tested data are taken during testing the model. The method is based on ANN is found to be reliable, cost-effective, and a quick tool for reasonably accurate estimation of CBR from the basic soil properties.

Effect of silica fume on engineering properties of expansive soil

In highway constructions, sub-grade and sub-base soil stabilization has been used as one of the prime and major process for many years in order to improve the engineering properties of soil. The strength of theses layers is indicated by their California bearing ratio (CBR) value which is quite expensive and time consuming. In order to overcome this situation, this study presents a methodology for predicting soaked California Bearing Ration (CBR) value of Black Cotton Soil Stabilized with Cement and Waste Glass Admixture using Multiple Regression Analysis (MRA). Experimental test results such Atterberg limit (Liquid limit (LL), Plastic limit (PL) and Plasticity index (PI)), Compaction characteristics of two compactive efforts namely standard proctor (SP) and modified proctor (MP) (maximum dry density (MDD) and optimum moisture content (OMC)), CBR, Waste glass (WG) content and Cement content (Cm), obtained from a laboratory at Abubakar Tafawa Balewa University Bauchi, Nigeria, have been employed in developing multiple regression models. California Bearing Ration was taken as the dependent variables while Liquid limit, Plastic limit, maximum dry density, optimum moisture content, waste glass content and Cement content were taken as independent variables. The regression analysis calculated the error mean square (MSE) for each possible model, and models with large MSE were not selected for the best regression equations. The best models have a minimum value of MSE occurring for the six-variable model (Cm, WG, LL, PL, OMCsp, MDDsp) and (Cm, WG, PL, LL, OMCmp, MDDmp) with a corresponding higher value of coefficient of multiple determination R2 = 0.98 and 0.94. The performance evaluation of the fitted regression models indicates a strong correlation (R2 = 0.89 - 0.98) between the mentioned variables, and the model equations developed from this work provided a very good prediction of the response, as the equations can be employed for making estimates of soaked CBR of other black cotton soils having similar geotechnical properties.

In India, expansive soils cover about 20% of total land area, these soils increase in volume (swell) during winter season and decrease in volume (shrink) during summer season. Due to this contradiction behaviour many civil engineering structures constructed on expansive soils get damaged severely, out of which pavement is the most because they are lightweight and extend over large areas. Stabilization of Expansive soil is of most importance, since to increase the strength of soil and to reduce the construction cost by making best use of locally available materials. The effects of Cement Kiln Dust (CKD) and Ceramic Dust (CD) on expansive soil by conducting the laboratory tests like Atterberg’s limit, Compaction characteristics, Unconfined Compressive Strength, California Bearing Ratio, and Free Swell Index etc were studied. Locally collected Black Cotton (BC) soil was mixed with addition of industrial waste materials such as; CKD and CD from 0 to 6% with an increment of 2%. From the analysis of test results, it was found that Liquid Limit (LL), Plasticity Index (PI), Optimum Moisture Content (OMC) and Free Swell Index (FSI) were decreased with an increment of CKD and CD percentage. Plastic Limit (PL), Maximum dry density (MDD), Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR) were increased with an increment of CKD and CD percentage. From this study we have concluded that CKD has very high lime (CaO) content up to 60% and CD has very high Silicon dioxide (SiO 2 ) because of these characteristics, they can be used as effective utilization in roads, embankment and soil treatment for foundation. Keywords : Expansive Soil, BC soil, soil stabilization, CKD, CD

The reutilization of waste plastic represents a significant concern due to its substantial economic and environmental impact. This article aimed to investigate the strength characteristics of clay soil stabilized by plastic bottles. We investigated the potential use of waste plastic bottles as sustainable soil stabilizers to enhance the geotechnical properties of clay soils. The experimental study involved collecting soil samples from the Wallaweyn District and performing laboratory tests, including unconfined compressive strength (UCS), California Bearing Ratio (CBR), Atterberg limits, and standard Proctor compaction tests, to determine the geotechnical properties of the clay soil. We added varying amounts of shredded plastic bottles (0.5%, 2%, 4%, and 6%) to soil samples to examine their effects on the geotechnical properties of clay soils. The addition of plastic bottles as reinforcement significantly increased the UCS and CBR values. The CBR and UCS test results indicate a direct correlation with the percentage of plastic bottles, up to 6%. The study findings demonstrated that the plastic content increased by 0.5%, representing the lowest of the observed percentages - 5% at shallower depths and 11% at greater depths - as reflected in the California Bearing Ratio. In terms of unconfined compressive strength, cohesion increased by 33.9% and 31.3% at QU. Moreover, the analysis identified that plastic content of 6% yielded the highest rate among all calculated percentages for both the California Bearing Ratio and unconfined compressive strength.

This study examined the effects of using bagasse ash in replacement of ordinary Portland cement (OPC) in the treatment of expansive soils. The study concentrated on the compaction characteristics, volume change, compressive strength, splitting tensile strength, microstructure, California bearing ratio (CBR) value, and shear wave velocity of expansive soils treated with cement. Different bagasse ash replacement ratios were used to create soil samples. At varying curing times of 7, 14, and 28 days, standard compaction tests, unconfined compressive strength tests, CBR tests, Brazilian split tensile testing, and bender element (BE) tests were carried out. According to X-ray diffraction (XRD) investigations, quartz and crystobalite make up the majority of the minerals in bagasse ash. Bagasse ash contains a variety of grain sizes, including numerous fiber-shaped particles, according to a scanning electronic microscope (SEM) test. For all of the treated specimens with various replacement ratios, the overall additive content has not changed. The results of the Brazilian split tensile tests demonstrate improved tensile strength for all specimens with various replacement proportions. A lower maximum dry density and a greater optimal water content would result from the substitution of bagasse ash. When the replacement ratio is not more than 20%, the CBR values of the parts replaced specimens are even higher than the cement treatments. The results of BE testing on the treated soils show that there is significant stiffness anisotropy but that it steadily diminishes with curing time and replacement ratio. According to the study, bagasse ash is a useful mineral additive, and the best replacement ratio (CBA20) is 20%.

Expansive soil is one among the problematic soils that has a high potential for shrinking when it is dried and swelling due to change of moisture content. Expansive soils (clays) popularly known as black cotton soils in India. Due to alternate swell-shrink behavior of expansive soils causes, distress in the foundation structures such as buildings, pavements of earth retaining walls etc. Understanding the behavior of expansive soil and adopting the appropriate control measures have been great task for the geotechnical engineers. Extensive research is going on to find the solutions for black cotton Soils. In this study, Nylon Fiber has been used in the form of fibers. The effect of the stabilisation was evaluated through carrying out standard laboratory tests. The tests included the standard compaction test, unconfined compressive strength (UCS) test, California Bearing Ratio (CBR) test. The main motive of this research is to investigate the optimal combination of Nano-Silica and Nylon Fiber with clay soil. The engineering properties such as liquid limit, plastic limit, maximum dry density and unconfined compressive Strength (UCS) are analyzed with virgin soil, the soil with Nano-Silica and combination of soil with Nano- Silica and Nylon Fiber. Three different combinations of Nano-Silica at different percentages 2%, 4% & 6% are used in integration with Nylon Fiber is used in different percentages such as 2.0%, 3.0% and 4%. From these experiments, it has been analyzed that with the increase of Nylon Fiber content in addition to Nano-Silica, the UCS increases and maximum value of UCS is obtained at 6% of Nano-Silica with 2.5% of Nylon Fiber. The intermixing of Nylon Fiber with the soil acts as a reinforcing material in binding the soil particles and the ‘bridge effect’ of fiber reinforcement in soil impedes the further development of tension cracks. Key Words: Compaction test, CBR, UCS, Nano Silica, Nylon Fiber

The geotechnical properties of lateritic soils from Ibienafe, South Ibie, Edo State, Nigeria, were assessed for pavement construction using both untreated and stabilized samples obtained from Locations A, B, and C. Due to similar geotechnical characteristics across sites, Location B was selected for stabilization. Laboratory analyses were performed in accordance with BS 1377: Parts 2 and 4 (1990), comprising specific gravity determination, particle size distribution, Atterberg limits, compaction characteristics, and California Bearing Ratio (CBR). Untreated soils, with a CBR of 36.35%, suited low-traffic subgrades but required stabilization. The results showed consistent specific gravity (2.54–2.56), fine-grained composition (84.36–85.13% passing 0.075 mm, classified as lean clay, CL), moderate plasticity (PI 11.58–12.02%), and compaction (MDD 1.85–1.90 g/cm³, OMC 11.03–14.16%). Stabilization with 2.5% and 5.0% Plantain Peel Ash (PPA) reduced CBR (31.05–34.09%), compaction (MDD 1.82–1.83 g/cm³, OMC 15.39–18.54%), and specific gravity (2.45), indicating limited benefits. Conversely, 2.5% and 5.0% Nano-Silica (NS) improved CBR (36.21–39.47%), reduced plasticity (PI 4.71–6.61%), and increased density (Gs 2.53–2.60). The 5.0% PPA and 2.5% NS combination yielded the highest CBR (48.55%), optimal compaction (MDD 1.79 g/cm³, OMC 18.13%), and low plasticity (PI 6.73%), ideal for subbase in light-traffic roads, highlighting NS’s superior stabilization and PPA-NS eco-efficiency.

The objective of this research is to improve dredged marine sediments with lime for potential use in earthfill works. Dredging work is usually necessary for coastal construction work and this material should be removed in an economical way. Marine clay samples used in the study were dredged in Gemlik Bay near Bursa, in Turkey. Geotechnical tests were conducted to determine the properties of the natural clay samples, including classification tests, unconfined compression (UC) and California bearing ratio (CBR) tests. The optimum lime content by weight was determined as 5 % using the Eades and Grim pH method, Atterberg limits and unconfined compression strength tests. Standard and modified Proctor tests were conducted to determine optimum water content and maximum dry density of the soil. Maximum dry density values decreased, optimum water content values increased, and Proctor curves becomes flatter with the addition of lime. Because the natural water content of the clay is around 40 % and the optimum water content of the samples with lime is around 16 %, not only hydrated lime but also quicklime is used for the improvement and drying of the marine clay soil. The original unconfined compressive strength and CBR value of the dredging soil were close to zero because of high water content. One month after improvement by lime, the unconfined compressive strength value reached 550 kPa and soaked CBR value was 35 without swelling. Unconfined compressive tests and CBR test results demonstrate that this type of marine clay can be improved with lime and can be economically utilized as a fill material in earthfill works.

CBR value research on soil stabilization with cement in the Budi Utomo UNIB Depan for influence soil properties and soil CBR original value after stabilisation with cement. Geotechnical Lab Testing was conducted at the Faculty of Engineering UNIB. Test laboratory soil properties include: density, water content, sieve analysis, Proctor standard test, Atterberg limits, and experimental value of CBR (California Bearing Ratio) laboratory. Stabilization soft soil made with cement with the addition of cement content of 0%, 2%, 4%, 8% and 12%. Based on test results propeties soil and the value of laboratory CBR. CBR maximum value at additioning cement content of 12%, the CBR value an increase of 144.21%, of the original soil conditions, dry density increase 3.85%, of the original soil, optimum moisture content decrease 13.75% of the original soil, PI value decresel 50.42% of the original soil, the value of specific gravity (Gs) increse 1.93% of the original soil. Stabilization with cement increasing the value of CBR, which means it will also boost the stability of the soil and will also increase the soil bearing capacity (qu). The increase in soil stabilization and soil bearing capacity proportional to the increase in the value of CBR amounted to 144.21%, this is due to the presence of silica, clay and limestone contained in the hydraulic cement is a binder.

The California Bearing Ratio (CBR) value is a crucial soil parameter in road construction and design. Obtaining representative CBR values is challenging, requiring time-consuming and expensive testing procedures. To address this issue, regression equations were developed to establish correlations between CBR and soil index properties. Laboratory tests were conducted to determine the soaked CBR, Liquid Limit (LL), Plastic Limit (PL), Plasticity Index (PI), Maximum Dry Density (MDD), and Optimum Moisture Content (OMC) of soil samples. Regression models were then created between CBR and different sets of soil index properties using Microsoft Excel 2007. Strong correlations were observed between soaked CBR, PL, PI, OMC, and MDD (R2 = 0.744); CBR, LL, PL, OMC, and MDD (R2 = 0.702); CBR, PI, OMC, and MDD (R2 = 0.643); CBR, LL, OMC, and MDD (R2 = 0.621); and CBR, OMC, and MDD (R2 = 0.602). Among all equations, the relation CBR = 0.72 PL – 1.22 PI + 2.34 OMC + 106.97 MDD – 222.46 exhibited the strongest correlation with a P-value of 0.005 and R2 of 0.744.

Effect of nano-silica on physio-mechanical properties and microstructure of soil: A comprehensive review