Conference Papers
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Item Stabilization of lateritic soil using bio-enzyme(2008) Mithanthaya, I.R.; Ravishankar, A.U.Soil stabilization is a technique aimed at increasing or maintaining the stability of a soil mass, or otherwise improving its engineering properties. Various techniques are being used for stabilization of soil. Sub-base is an integral part of the road pavement structure. The main function of the sub-base is to provide a stress transmitting medium for spreading the surface wheel load in such a manner as to prevent shear and consolidated deformations. A number of researchers worked on characterizing variousus properties of the laterite soil and found that the following problems could be associated with the laterite: 1)In the majority of cases, the laterite doesn't satisfy conventional specifications for road construction materials especially road base. 2) The laterit undergoes property changes during construction; gradation being considered to be the most sensitive. To improve on the above deficiencies and consequently to improve on there field performance characteristics, laterites need to be stabilized. Bioenzyme - stabilization is a newer technique for strengthening the sub-base soil. The Bioenzyme alters the engineering properties of soil such as the capacity to bear loads. These enzymes are liquid additives, which act on the soil to reduce the voids between soil particles and minimize absorbed water in the soil for maximum compaction. The locally available laterite soil procured from the field is used to improve the strength and bearing capacity. One type of Bio-enzyme namely TerraZyme has been used for stabilization of laterite soil. In this study soil with variable enzyme dosages were tested for stabilization process and strength of the stabilized soil has been evaluated after curing period of one week, two weeks, three weeks and four weeks. The tests were carried out to determine the consistency limits, CBR, unconfined compressive strength and permeability of the soil specimens with and without enzyme for a curing period of one week to four weeks. The effect of enzyme on different percentages of sand blended laterite soil was also studied for the curing periods. The enzyme treated soil showed significant improvement in CBR (California bearing ratio) and UCS (Unconfined Compressive strength) with curing. © AES-Advanced Engineering Solutions.Item Experimental Studies on Lateritic Soil Stabilized with Cement, Coir and Aggregate(Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2021) Ravi Shankar, A.U.R.; Priyanka, B.A.; AvinashThe characteristics of subgrade soil play a vital role in designing the pavement structure so that the pavement has required support from the bottom layer. During adverse weather conditions and higher traffic loads moving on any pavement, it should be able to withstand the impact and perform well for longer duration. Load is transmitted from pavement to the subgrade layer and distributed evenly through the soil particles. All types of soil are not capable of handling such impacts by their own and needs additional stabilization processes. Several stabilization processes are available in which the best one has to be taken into consideration. Fibers such as coconut coir are important in giving extra stability to the soil particles. Cement is well-known material in construction sector along with aggregates. Lateritic soil is available abundantly in coastal areas of southern parts of India which has porous structure and demands stabilization when the intended purpose is specific and requires higher strength and durability. In this study, coconut coir along with cement and aggregate are taken as stabilization materials to stabilize lateritic soil. Initially, basic properties of soil like plastic limit, liquid limit and plasticity index are determined. Grain size analysis is done and modified Proctor test is conducted to determine the optimum moisture content (OMC) and maximum dry density (MDD) of the soil. Unconfined compression test (UCS), California bearing ratio test (CBR), flexural fatigue analysis, durability properties with respect to wet-dry cycles and freeze–thaw cycles are evaluated for untreated and treated soil specimen. As per UCS values, cement can be taken at an optimum dosage of 6%. The coir fibers from natural husk of coconut and aggregates of 10 mm below size were added to the soil–cement mixes and an optimum dosage of coir and aggregate is determined. The study showed positive results in terms of CBR values of cement-aggregate treated soil. © 2021, Springer Nature Singapore Pte Ltd.Item Improvement in the Properties of Red Soil Using Granulated Blast Furnace Slag(Springer Science and Business Media Deutschland GmbH, 2022) Preetham, H.K.; Nayak, S.; Jagapur, P.In the current study, an attempt is made to improve the geotechnical properties of red soil using industrial by-product: Granulated-Blast Furnace Slag (GBFS). Red soil is distributed over large part of the peninsular region in India. Red soil could be effectively stabilized to yield better strength characteristics. GBFS is the primary by-product of the iron and steel industry. Red soil was replaced with varying percentages of admixture (GBFS) by dry weight of soil (5, 10, 15, 20 and 30%). Basic geotechnical properties like specific gravity, Atterberg limits, compaction, unconfined compressive strength (UCS) and triaxial compression test, were performed on the red soil as well as on the mixes as per Indian Standard Codal provisions. From the UCS test results, the optimum percentage of replacement of 15% was found. It was observed that on replacement with admixtures, the liquid limit was found to decrease which reduces the compressibility. The presence of CaO in GBFS has improved the shear strength and shear strength parameters of soil. Thus utilization of granular industrial by-product (GBFS) has proven beneficial in geotechnical structures. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Assessment of the Geotechnical Properties of Red Earth Stabilized Using Quarry Dust and Cement(Springer Science and Business Media Deutschland GmbH, 2022) Nayak, S.; Preetham, H.K.; Prakash, S.D.The present investigation aims at improving the engineering properties of red earth by incorporating quarry dust (QD) and analyze the results thus obtained by conducting a comparative study with the basic soil. Red earth is widely spread over a large part of peninsular India. Red earth/red soil could yield better results by the addition of rough-textured granular quarry dust and a hydraulic binder like cement. QD is the output from the rubble crushing units. Red earth was replaced with different proportions of quarry dust by dry mass of the soil: QD (5–30%, with an increment of 5%) with cement (2–6%) for the optimum QD-soil mix. The geotechnical properties like specific gravity, consistency limits, compaction, unconfined compressive strength (UCS), and triaxial compression test were performed on the red earth as well as on the mixes as per Indian Standard Codal provisions. UCS test results conclude that an optimum percentage of replacement of red earth by QD is 10% which yielded maximum strength than other mixes. It was observed that on replacement of red earth by granular quarry dust and cement, the shear strength properties and other geotechnical properties were improved. Thus, the utilization of granular industrial by-products has proven to be socially and economically beneficial. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Laboratory Investigations on Lateritic Soil Stabilized with RBI Grade 81, Coconut Fiber and Aggregates(Springer Science and Business Media Deutschland GmbH, 2022) Chethan, B.A.; Ravi Shankar, A.U.Soil stabilization is an excellent old technique adopted to improve the properties of any weak soil. In the recent past, many chemical stabilizers came to the market. In this study, a commercial stabilizer-RBI Grade 81’s (dosage 2–8%) potential to improve lateritic soil properties was investigated. At 6% RBI Grade 81 dosage, the effect of reinforcement was evaluated by using 0.5 and 1.0% coconut fibers. Strength improvement of 6% RBI Grade 81 stabilized soil admixed with <12.5 mm size aggregates (5, 10, and 15%) was studied to know the effect of granular layer demolition waste incorporation. CBR and UCS tests were used for strength evaluation. Considerable improvement in mix strength was observed above 6% RBI Grade 81 dosage on 28 curing days for the soil incorporated with fibers and aggregates. A linear fit was established between UCS and soaked CBR, which shows a high correlation (>0.9), and Prob > F is <0.06 depicting high reliability for the estimation of soaked CBR from UCS. Further, fatigue and durability tests were carried out to understand stabilized soil’s behavior under dynamic load application and performance during monsoon to simulate the submerged condition of the pavement in dense rainfall areas (>3500 mm). Stabilized lateritic soil mixes sustained freeze–thaw cycles effectively with weight loss of <14%. However, even at an 8% RBI Grade 81 dosage, the mix has not satisfied the wetting–drying test requirement. Stabilized soil blends showed excellent fatigue performance under repeated loads. The 6% RBI Grade 81 treated soil mixes can be used for modified subgrade. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.Item Laboratory Investigation of Lateritic Soil Stabilized with Arecanut Coir Along with Cement and Its Suitability as a Modified Subgrade(Springer Science and Business Media Deutschland GmbH, 2023) Chethan, B.A.; Lekha, B.M.; Ravi Shankar, A.U.If a pavement is constructed on weak soil, its lifespan drastically reduces due to the low strength induced by moisture-induced destresses. Such soils may undergo considerable changes in volume. In order to modify these properties, soil stabilization can be done. By stabilizing the soil along with the improvement in strength, its durability can be increased. Stabilization may be of chemical or mechanical type. In this investigation, lateritic soil was stabilized using 0.2–1% arecanut coir, and its compaction characteristics were evaluated. The lateritic soil is found to be nondurable. The reinforcement alone could not improve the strength and durability effectively. Therefore, 3% binding agent ordinary Portland cement (43 grade) was added to the mix. Due to cement stabilization, UCS and CBR values were improved, and the optimum values were observed at 0.6% arecanut coir dosage. The addition of cement has resulted in a change in silica, alumina, and calcium oxide contents, thereby contributing to the formation of hydration products. The samples with 1% coir and cement have completed 12 wet–dry cycles, but the weight loss observed was >14%. All the specimens showed low soil loss under freeze–thaw cycles. The performance of cured specimens under fatigue loading was satisfactory. Since the specimens could not pass wet–dry durability criteria, they can be considered for modified subgrade. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.