Influence of Lime for Enhancing Characteristics of Expansive Soils in Road Works

Expansive soils are found in black cotton soils, which swell or shrink in volume when presented to changes in moisture content. Lime treatment is exhaustively used to increment the properties of sensitive and fragile soils. One of the hugest clarifications behind using lime is to decline the developing presentation of the earth soil. The arrangement of extra safeguards improves the reaction of quicklime (CaO) with water, structures hydrated (slaked) lime (Ca (OH)2), and thus earth characteristics. The vast inadequacy of employing lime is growing the deficiency of lime offset earth. Following that, the goal of this study is to see how re-establishing time affects the geotechnical qualities of settled Black cotton soils with lime. These discoveries recommend that adding Lime as a stabilizer works on the strength of black cotton soil. Some of the characteristics of the soil likely to be increased by using stabilizer in this work are UCS (Unconfined Compressive Strength) at different curing periods (7,14,28 and 56 days), CBR (California Bearing Ratio) value at unsoaked and soaked and MDD (Maximum Dry Density) decrease at different lime percentages(%) like 2.4.6.8 and 10. The result showed here untreated soil got stabilized by using the stabilizer in certain extent In this adjustment various rates of cementitious material is added to black cotton soil and directed tests like plasticity, compaction, swell pressure, free swell index(FSI), Coefficient of permeability (k) and CBR(soaked and unsoaked) at various conditions like OMC,OMC+2% water and OMC+5% water, UCS (Unconfined Compressive Strength) was performed. From the test results, it is identified that the stabilization agent decreases plasticity and improves strength characteristics. Addition of stabilizing agent makes the black cotton soil to non-plastic, non-swelling and attains increase CBR values which are greater than 25% for a dosage of 10% lime at OMC but remaining OMC+2%water & OMC+5%water CBR values are not various much difference as per test results. With the addition of lime, the black cotton soil becomes non-plastic, non-swelling, and has high strengths. Treated soils are used as a development material, for example, a subgrade layer in the development of adaptable asphalt pavements for roads.

Stabilization of B.C. Soil by Using Chemicals and Fly Ash

Black cotton soils are very susceptible to detrimental volumetric changes with changes in moisture. This behaviour of soil is attributed to the presence of mineral montmorillonite which has an expanding lattice. Black cotton soils because of their specific physical and chemical make are subjected to volume changes. In many countries including India, these soils are so extensive that alteration of highway routes to avoid the material is virtually impossible. Various remedial measures like soil replacement, prewetting, moisture control, lime stabilization etc. have been practiced with varied degrees of success. Extensive research is going on to find the solutions to Black cotton soils. Recent investigations on chemical stabilisation revealed that electrolytes like Calcium Sulphate, Calcium Carbonate, Zinc Chloride can be used in place of conventionally used lime, due to their ability to supply adequate cations. Fly ash is a waste by product from thermal power plants consuming thousands hectors of precious land for its disposal and also causing severe health and environmental hazards. This work presents the results of an experimental program undertaken to investigate the effect of Calcium Sulphate, Calcium Carbonate, Zinc Chloride and fly ash at different percentages on properties of black cotton soil. Atterbergs Limit of subgrade soil effect of addition of Fly Ash and Chemicals on CBR ,MDD ,OMC, From the results it is observed that 2% of Zinc Chloride and 12% of Fly ash improves the properties of black cotton soil as compared to Calcium sulphate & Calcium Carbonate. The conclusion drawn from this investigation is that a combination of 2% of chemicals and 12% of fly ash is more effective in improving the properties of black cotton soil.

Alternanthera sessilis (sessile joyweed).

A. sessilis is a pioneer species typically growing on disturbed areas and in wetland habitats, and regarded as a fast-growing highly invasive weed. It is adapted to grow on a range of soil types ranging from poor sandy or alkaline soils, to loam or black cotton soils. It is also able to grow in seasonally-waterlogged areas as well as in areas with extreme dry conditions (Holm et al., 1997). A. sessilis can be found invading floodplain wetlands, margins of rivers, streams, canals, ditches, ponds, reservoirs, tanks, marshes, swamps, wet low-lying ground, ephemeral pools, seasonal pans and damp forest. This species is also a weed in fields with sorghum, millet, Eleusine spp., maize, cotton, cassava, cereal crops, pastures, and vegetable farms (Gupta, 2014). Consequently, this species has been listed as invasive in India, South Africa, Namibia, Spain, Hawaii and many other islands in the Pacific Ocean (see distribution table for details). It is also listed as a noxious weed in the United States (USDA-NRCS, 2014).

Stabilization of Black Cotton Soil using Lime and Phosphogypsum

Expansive soils are problematic soils for Civil Engineers. Black cotton (BC) soils possess low strength and high compressibility, due to these properties black cotton soils are considered to be challenging one for analysis. To achieve desired properties of soil for construction purpose these black cotton soil must be enhanced to meet its requirement. To modify the properties of black cotton soils, many treatment methods are there. In this paper an attempt has been made to improve the properties of black cotton soil by using industrial waste through stabilization method. By stabilizing the soil properties are enhanced and make it suitable for subgrade construction. In this work, the combined effect of Lime and Phosphogypsum (PG) on compaction characteristics, Atterberg’s Limit, Unconfined Compressive Strength (UCS) for original soil, California Bearing Ratio (CBR) and direct shear Test of a black cotton soil with percentage varying of Lime and Phosphogypsum was carried out. The soil samples were tested for tri-axial compression test and CBR tests were carried out after 4 days curing period. From the results, it has been inferred that the black cotton soil treated with Lime and Phosphogypsum in the percentages of (4:4) has better strength characteristics. Hence, it may be concluded that Lime and Phosphogypsum can be used for stabilization of black cotton soils for pavement subgrade

Effect of Water Regimes on the Growth of and Yield of Rabi / Summer Groundnut Genotypes in Northern Transition Zone of Karnataka

Background: Groundnut crop grown during Rabi / summer experiences moisture stress, thus irrigation is must. However, water for irrigation gets scarce during summer month hence it becomes important to choose stress tolerant varieties and optimize irrigation schedule without compromising the yield.Methods: A field experiment with four rabi / summer groundnut genotypes (G1: Dh-86, G2: Dh-101, G3: K-9 and G4: G2-52) exposed to four irrigation regimes (I1: 7 irrigations at 15 days interval from sowing to 105 DAS as control, I2: withdrawal of one irrigation between 45 - 60 DAS i.e., pegging stage, I3: withdrawal of two irrigations between 45-75 DAS i.e., at pegging and pod filling stage, I4: withdrawal of four irrigations from 45-105 DAS i.e., at pegging, pod filling and kernel development stage) was carried out from December to April of 2016-17 on black cotton soils at AICRP on Groundnut UAS, Dharwad.Result: Among the genotypes tested, Dh-86 recorded significantly higher pod yield (2,376 kg ha-1) followed by Dh-101 (2,215 kg ha-1) and K-9 (2,048 kg ha-1), whereas G2-52 gave the lowest yield (1,880kg ha-1) and all of them performed well at I1 and I2 irrigation regimes. Among different water regimes, I1 (i.e., control) recorded significantly taller plants, higher LAI, more branches and higher dry matter at harvest as compared to other irrigation regimes, hence it also recorded significantly higher pod yield and haulm yield (2,870 and 4,691 kg ha-1, respectively), but was found at par with I2, i.e., crop stressed only at pegging stage (2,858 and 4,648 kg ha-1, respectively). This suggests that, at the most, one irrigation can be skipped at pegging stage without compromising on yield.

Stabilization of Black cotton soil using Fly ash

Expansive Black cotton clay soils are widely distributed worldwide, and are a significant damage to infrastructure and buildigs.It is a common practice around the world to stabilize black cotton soil using fly ash to improve the strength of stabilized sub- base and sub grade soil. Soil stabilization is the improvement of strength or bearing capacity of soil by controlled compaction, proportioning or addition of suitable admixtures or stabilizers. The Black cotton soils are extremely hard when dry, but lose its strength fully when in wet condition. In monsoon they guzzle water and swell and in summer they shrink on evaporation of water from there. Because of its high Swelling and shrinkage characteristics the black cotton soils has been a challenge to the highway engineers.So in this research paper fly ash has been used to improve the various strength properties of natural black cotton soil.The objective of this research paper is to improve the engineering properties of black cotton soil by adding different percentage of fly ash by the weight of soil and make it suitable for construction. A series of standard Proctor tests (for calculation of MDD and OMC) and California Bearing Ratio (C.B.R) tests are conducted on both raw Black cotton soil and mixed soil with different percentages of fly ash (5%, 10%, 20%, 30%) by weight. A comparison between properties of raw black cotton soil, black cotton soil mixed with fly ash are performed .It is found that the properties of black cotton soil mixed with fly ash are suitably enhanced.