Journal Articles

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    Effect of soil parameters on dynamic cone penetration indices of laterite sub-grade soils from India
    (2009) George, V.; Nageshwar Rao, Ch.; Shivashankar, R.
    The focus of this study was on correlating the effect of grain-size, maximum dry-density (MDD), field moisture content, and the void ratios on penetration measured using the dynamic cone penetrometer (DCP) for laterite soils blended with fines. Tests were performed on soil samples compacted to MDD for moulding water contents set to the optimum moisture content (OMC), dry of OMC, and wet of OMC un-soaked condition. The results indicated that an increase in the fines-content caused a decrease in the MDD, and an increase in the OMC and the DCP penetration. Regressions were developed correlating various parameters. © Springer Science+Business Media B.V. 2008.
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    A comparative study on properties of porous friction course mixes with neat bitumen and modified binders
    (2009) Suresha, S.N.; George, V.; Ravi Shankar, A.U.R.
    This paper summarises details of the laboratory investigation on the effect of various binders on the performance and durability of porous friction course (PFC) mixes. Three different modified binders and neat bitumen were investigated for three different aggregate gradations at two predetermined binder contents. The performance was evaluated in terms of stone-on-stone contact condition, air voids, and hydraulic-conductivity of compacted PFC mixes. The structural durability was investigated based on aged abrasion loss and moisture susceptibility. The findings provide a better understanding of the effect of each binder type on the performance and durability of PFC mixes. Crown Copyright © 2008.
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    PFWD, DCP and CBR correlations for evaluation of lateritic subgrades
    (2009) George, V.; Rao, N.C.; Shivashankar, R.
    The evaluation of subgrade strength plays a major role in pavement design. An understanding of subgrade properties enables the selection of road materials for sub-base and base courses. In developing countries like India, apart from the use of well-established traditional pavement evaluation techniques such as the California bearing ratio (CBR) test and the dynamic cone penetrometer (DCP) test, the use of non-destructive testing devices such as the portable falling weight deflectometers (PFWDs) has gained popularity in recent years. This is mainly because of the inherent capability of PFWDs in obtaining quick estimates of the modulus of subgrade in addition to their simplicity in design and portability. Thus, there exists a need to correlate the results obtained using PFWDs with those obtained using traditional approaches such as the CBR and the DCP for the benefit of road engineers. This work focuses on exploring the correlations between these approaches for lateritic soils in Dakshina Kannada district, India.
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    Characterization of porous friction course mixes for different Marshall compaction efforts
    (2009) Suresha, S.N.; George, V.; Ravi Shankar, A.U.R.
    Porous friction courses (PFCs) are mainly recommended as surface drainage layers on high-speed road-corridors and runway pavements. Permeability and sound attenuation characteristics are considered to be the indices for performance assessment of PFCs. One of the reasons for the loss of permeability in PFCs is densification under heavy traffic. But, resistance to ravelling too, is of main concern in the case of under-compacted PFCs. This paper summarises the details of laboratory investigation on the characterization of PFC mixes corresponding to four different gradations and two binder contents, for three levels of the Marshall compaction. The findings of the investigation suggest that the selection of the compaction level for PFC mix design should be based on the design traffic level, and the gradation selected. © 2009 Elsevier Ltd. All rights reserved.
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    Evaluation of properties of porous friction course mixes for different gyration levels
    (2009) Suresha, S.N.; George, V.; Shankar, A.U.R.
    Porous frictions courses (PFCs) are characterized by high percent air voids content, and are widely used as pavement surface drainage layers. This paper presents details on the laboratory investigation performed on evaluation of properties of PFC mixes using the Superpave gyratory compactor. It also, provides a brief review of the latest specifications related to standard practices for mix design and the uses of these mixes adopted by various agencies. Major differences were observed in the design gyrations (Ndesign) and the design aggregate gradations. In this study, six gradations (G) were investigated with binder contents (BCs) ranging between 4.0 and 5.0% by mass of the total mix, for various gyration levels (N). The effect of N, G, and BC on the volumetric properties, unaged abrasion loss, permeability, and the permanent deformation characteristics of PFC mixes were investigated. The experimental results were statistically analyzed to identify the major influencing factors and their significance. © 2009 ASCE.
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    Laboratory and theoretical evaluation of clogging behaviour of porous friction course mixes
    (2010) Suresha, S.N.; George, V.; Ravi Shankar, A.U.
    The clogging of porous friction courses (PFCs) plays a major role in their resulting performance. Clogging occurs due to deposition of external and internal materials, leading to the loss of permeability and drainage characteristics of PFCs. In this study, investigations were conducted to determine the effect of clogging and de-clogging on the permeability of PFC mixes. Tests were conducted to study the effect of three different clogging materials on PFC mixes prepared using four different aggregate gradations. Permeability tests were conducted using the falling-head concept on cylindrical PFC specimens. The influence of the particle size ratios and the effective air voids on the permeability of fresh, clogged and de-clogged PFC specimens was analysed. Experimental results on the permeability observed were compared with those predicted using theoretical models. Although, the theoretical models tend to overestimate the permeability values, statistical analyses indicate good correlations with the observed results.
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    Effect of aggregate gradations on properties of porous friction course mixes
    (2010) Suresha, S.N.; George, V.; Ravi Shankar, A.U.
    This paper presents the study on effect of aggregate gradation on the mix design and performance properties of porous friction course (PFC) mixes. Six aggregate gradations were tested with due consideration to gradations specified for PFC or similar mixes by different agencies around the world. The PFC mixes were characterized for volumetric properties, permeability, unaged and aged abrasion loss, moisture susceptibility, and rutting resistance. The results were statistically analysed to identify the factors that significantly influence the properties of PFC mixes. Findings of the study clearly indicate that the gradations specified by various agencies will have significant effect on the design properties of PFC mixes, thus they are different. It also, helps in framing the Master aggregate gradation band for PFC mixes. Generally, permeability property is considered to be an optional parameter in the design. However, the findings of the present study recommended considering the permeability as one of the prime parameters in the design of PFC mixes. © RILEM 2009.
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    Properties of cellulose fibres and waste plastic modified porous friction course mixes
    (2010) Suresha, S.N.; George, V.; Ravi Shankar, A.U.
    This paper summarises the laboratory investigation on porous friction course mixes that were modified with cellulose fibres and waste plastics. Porous friction course mixes of three different aggregate gradations were tested for predetermined binder content. The influence of each modifier on the volumetric properties, permeability, aged abrasion loss, and moisture susceptibility of porous friction course mixes were evaluated. In order to determine the significance level of effect of modifiers on the above properties, the tests for analysis of variance (ANOVA) and Tukey's multiple mean comparisons were performed. Results of statistical analyses indicate that the gradations are major source of variations in all response properties. However, modifiers too appreciably contributed in reducing the moisture-induced damages. The findings suggest that shredded waste plastics are potentially useful as modifiers to porous friction course mixes.
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    Traffic management proposals for Udupi city
    (CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2011) Mulangi, R.H.; Ravi Shankar, A.U.; George, V.
    Udupi is amongst the most prominent places of pilgrimage in India and is famous for its Lord Krishna and many other deities. It is having population of 1.476 lacks in the year 2002, with floating population 100000 to 200000 per day. In view of growing importance of the Udupi city in the region of Central Business District (CBD), this is an urgent need for a comprehensive approach to tackle the short range and long-range traffic and transportation problems. To study the existing traffic and transportation system and prepare traffic management plan various traffic surveys have been carried out, and alternate proposal have been made. The proposals have been analysed for Level of Service (LOS) along the urban roads and LOS of turning traffic at junctions for next ten years. In present study an attempt is made to provide traffic management for CBD area. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
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    Effects of soil parameters and moisture content on stiffness of unsaturated blended laterite using tri-axial tests for rural roads
    (2011) George, V.; Nageshwar Rao, C.; Shivashankar, R.
    Evaluation of subgrade strength and stiffness is essential in the design of pavements and construction of embankments for highways in order to ensure that roads perform their functions satisfactorily over a longer period. The grain size distribution and compaction moisture-content have an immense influence on the strength and stiffness of subgrades. Among the various laboratory tests for evaluation of shear strength parameters, and the modulus of elasticity of subgrades, the tri-axial test plays a major role in describing the geotechnical characteristics of the subgrade. This paper deals with an experimental investigation on unsaturated laterite soils blended with varying percentages of fines. It focuses on a study of the influence of various soil parameters on the stiffness and strength of soil samples compacted at optimum moisture content (OMC), at the drier side of OMC, and also at the wetter side of OMC, and the development of meaningful correlations. © 2011 CAFET-INNOVA TECHNICAL SOCIETY.