Role of Fly Ash on Strength Properties of Rejuvenated Soil Cement for Pavement Materials

Stabilization with cement is the most commonly used technique for the improvement of soil physical, mechanical, and engineering properties. This research reported on the properties of the rejuvenation for recycled soil cement with incorporation of fly ash (FA). The study showed that the specific gravity of Rejuvenated Soil Cement (RSC) decreased with increasing FA. The free swell ratio and linear shrinkage of RSC were significantly decreased with the increase in FA. The maximum dry unit weight of RSC increased with increasing FA up to the optimum FA content of 20 – 25 %. The optimum water content in compaction was relatively constant with the increase in FA. Particularly, the strength improvement in active zone of FA-RSC was influenced by several factors viz., compaction, packing, rehydration, and pozzolanic reaction. As a result, the unconfined compressive strength (UCS) of RSC increased with increase in FA and curing time. This research clearly showed that the rejuvenation of soil-cement with FA as additive was successful. It was also shown that the normalized UCSs of RSC at various curing times could be used to predict the UCSs at 7 and 28 days.

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.

Stabilization of Expansive Soil Using Biomedical Waste Incinerator Ash

Expansive soils undergo high volume change due to cyclic swelling and shrinkage behavior during the wet and dry seasons. Thus, such problematic soils should be completely avoided or properly treated when encountered as subgrade materials. In the present study, the biomedical waste incinerator ash and lime combination was proposed to stabilize expansive soil. Particle size analysis, Atterberg limits, free-swell, compaction, unconfined compression strength, and California bearing ratio tests were conducted on the natural soil and blended with 3%, 5%, 7%, 9%, and 11% biomedical waste incinerator ash (BWIA). The optimum content of BWIA was determined based on the free-swell test results. To further investigate the relative effectiveness of the stabilizer, 2% and 3% lime were also added to the optimum soil-BWIA mixture and UCS and CBR tests were also conducted. In addition, scanning electron microscopy (SEM) tests for representative stabilized samples were also conducted to examine the changes in microfabrics and structural arrangements due to bonding. The addition of BWIA has a promising effect on the index properties and strength of the expansive soil. The strength of the expansive soil significantly increased when it was blended with the optimum content of BWIA amended by 2% and 3% lime.

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.

Laboratory Study on Improvement of Expansive Soil by Chemically Induced Calcium Carbonate Precipitation

This paper proposes the use of calcium carbonate (CaCO3) precipitation induced by the addition of calcium chloride (CaCl2) and sodium carbonate (Na2CO3) solutions as a procedure to stabilize and improve expansive soil. A set of laboratory tests, including the free swell test, unloaded swelling ratio test, unconfined compression test, direct shear test, scanning electron microscopy (SEM) test, cyclic wetting–drying test and laboratory-scale precipitation model test, were performed under various curing periods to evaluate the performance of the CaCO3 stabilization. It is concluded from the free swell tests and unloaded swelling ratio tests that the addition of CaCl2 and Na2CO3 can profoundly decrease soil expansion potential. The reduction in expansion parameters is primarily attributed to the strong short-term reactions between clay and stabilizers. In addition, the formed cementation precipitation can decrease the water adsorption capacity of the clay surface and then consequently reduce the expansion potential. The results of unconfined compression tests and direct shear strength tests indicated that the addition of CaCl2 and Na2CO3 has a major effect on geotechnical behavior of expansive soils. Based on the SEM analyses, new cementing crystalline phases formatted by sequentially mixing CaCl2 and Na2CO3 solutions into expansive soil were found to appear in the pore space, which results in a much denser microstructure. A laboratory-scale model test was conducted, and results demonstrate the effectiveness of the CaCO3 precipitation technique in stabilizing the expansive soil procedure. The test results indicated that the concentration of CaCl2 higher than 22.0% and Na2CO3 higher than 21.2% are needed to satisfactorily stabilize expansive soil. It is proposed to implement the precipitation technique in the field by the sequential permeation of CaCl2 and Na2CO3 solutions into soils in situ.

Analysis Of The Residual Red Soil Shear Test With The Slurry Method In The Regency Of Semarang

Residual soil is found in most areas with mountainous, hilly, and undulating topography. This soil is marked by red or brown color. This study aims to determine the physical and mechanical properties of soil in the original soil and residual soil conditions using the slurry method. Research objects were taken from residual red soil of The East Ungaran District, Bergas District, and Bawen District. Analysis of the physical and mechanical properties test shows that the soil sample is a type of clay with kaolinite constituent minerals and moderate swelling ability, and direct shear testing from locations L1, L2, and L3 obtained residual peak shear angles using the slurry method of 29,249 °; 31,341 °; 31,964 ° and constant residual shear angle value of 8,082 °; 8,138 °; 7,294 °, the value of the original soil shear angle has a value of 32.82 °; 31.44 °; 31.98. The higher the value of the plasticity index, the higher the value of the free swell. The relationship between the plasticity index and the value of the residual peak shear angle shows that the results of the peak shear angle and the plasticity index are still within the scope of standard deviation. The value of the constant residual shear angle with the slurry method is much smaller than the test result graph.

Fluid Intake Capacity of Aloe Vera and Sea Cucumber Thin Film

Aloe Vera and sea cucumber are the natural material which has been used widely in bio-medical field in Malaysia, especially for wound healing purposes due to its therapeutic effects. Recently, thin films which can absorb acceptable amount of fluid has been gaining attentions in biomaterial wound dressing applications. Hence, the incorporation of these natural materials in the fabrication of the thin films were investigated regarding the fluid intake capacity under the condition of being in contact with deionized water and pseudo-wound exudate. Three types of films made of different compositions of Aloe Vera and sea cucumber were prepared and evaluated. The morphology of the films was analysed using the Scanning Electron Microscopy (SEM) evaluation and the fluid intake capacity through the Free Swell Absorptive Capacity test. Results showed the variety of fluid intake capacity of different type of the film after being immersed in both solutions. The morphological structure of each film also varied from one another. The result also indicated that the Aloe Vera film held the adequate fluid intake capacity without any degradation behaviour.

Multivariate Assessment of California Bearing Ratio with Contrasted Geotechnical Properties of Soils in Ilorin-Lokoja Highway

California Bearing Ratio (CBR) is an important parameter used in designing pavement layers in road construction but testing this parameter requires time, labor, and huge cost. The study therefore applies multivariate approach to evaluate CBR based on contrasted geotechnical parameters along Ilorin-Lokoja highway. The results obtained showed that the migmatite-gneiss-derived soils are slightly more fines (< 0.075 mm; 7.4–59.6%), more plastic (PI; 1.6–39%), and have low strength (MDD = 1.8 mg/m3; CBR = 29.0%) than the metasediments (11–57.7%, 2.0–30%, 1.6 mg/m3, 23.6%) and older granite soils (8.2–32.7%, 2.6–13.4%, 1.7 mg/m3, 27.8%), respectively. The principal component analysis (PCA) revealed three major components (eigenvalues >1) which accounted for 83.8% of the total variance at the rate of 33.4, 14.7, and 11.4%. Major contributing variables for the components were fines (R = 0.87), plasticity index (R = 0.7), and coarse sand (R = 0.67%). Spatial distribution of these groups established interplay of sediment-gradation and moisture-connection evident in hierarchical cluster analysis that revealed patterns of homogeneity and soil relationships. Regression analysis established five models from predictor variables such as fines, activity, free swell, liquid and plastic limits, weighted plasticity index, optimum moisture content, and maximum dry density with the coefficient of determination (R2 = 0.33) and root mean square error (RMSE) of 7.80.

Evaluation and Comparison of Structurally Different Cellulose-Based Hemostatic Agents in a Rat Kidney Model

Different topical hemostatic materials are used to achieve effective hemostasis. High hemostatic activity, biocompatibility, bioresorbability, and easy manipulation are to be expected in such a developed product. In the surgical world with these specific requirements, finding a proper hemostatic agent is very difficult. The study compared several materials of various construction properties, which were assessed for structural and related properties by morphological analyses and assessed in vivo for their efficiency and behaviour using a model of rat partial nephrectomy. New sodium salt of carboxymethyl cellulose (CMC) sponge with the lowest porosity and free swell absorptive capacity contained the highest amount of hydroxyl and carboxyl groups. Results revealed that this CMC material in the form of a bioresorbable sponge may ensure the necessary hemostatic effects, while also providing a positive influence on the reaction of the local tissue. The CMC material also needed significantly less time to achieve hemostasis (p < 0.001). Moreover, the sponge reached satisfactory results in the histopathological evaluation with the lowest destruction score and favorable healing reaction. This modified product proved itself to be a promising bioresorbable hemostat, which, according to its design, matches with its surgical applications. In general, the obtained data elucidated the dependency of the total effect on its structure and composition.