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Item Mechanical properties of pavement quality concrete produced with reclaimed asphalt pavement aggregates(Springer, 2019) Panditharadhya, B.J.; Mulangi, R.H.; Ravi Shankar, A.U.; Kumar, S.Production of conventional coarse aggregates for concrete works is getting difficult because of depleting natural resources and environmental ill effects. Reclaimed Asphalt Pavement (RAP) aggregates, which are produced from asphalt waste generated during removal of flexible pavement. The disposal problems of asphalt waste generated is also addressed with this step. The properties of RAP aggregates may vary with the source of waste generation and the age of the asphalt. This study is taken up to determine the strength characteristics of pavement quality concrete produced with RAP aggregates produced with asphalt waste generated at local road construction site. Properties such as compression strength, elastic modulus, flexural strength, split tensile strength, and water absorption were determined for the specimen with varying percentage of RAP replacement. The asphalt waste was processed further with screening to obtain the required gradation. RAP aggregates were replaced with conventional aggregates by 20, 40, 60, 80, and 100%. Mix with 60% conventional granite aggregates and 40% RAP aggregates was found to satisfy the requirements of M30 grade concrete that can be used for producing concrete for constructing the roads with lower traffic volume. © Springer Nature Singapore Pte Ltd. 2019.Item SMA mixtures with modified asphalt and treated aggregates(American Society of Civil Engineers (ASCE) onlinejls@asce.org, 2014) Goutham, G.; Lekha, B.M.; Monisha, M.; Ravi Shankar, A.U.Stone Matrix Asphalt (SMA) is a gap-graded asphalt rich mix with a high concentration of coarse aggregates. In the present investigation, SMA mixtures were prepared with chemically treated aggregates and Crumb Rubber Modified Bitumen (CRMB), and were compared for various characteristics. SMA samples were prepared in conventional Marshall and Superpave Gyratory Compactor (SGC) methods. Volumetric and Marshall properties, Indirect Tensile Strength (ITS), rutting and moisture susceptibility, fatigue behaviour and permeability characteristics were determined for these mixtures. From the laboratory studies it is evident that, chemically treated aggregates with normal bitumen (Viscosity Graded (VG) 30) and CRMB with normal aggregates can be used in SMA to meet the drain down requirements. CRMB mixes were observed to be having an upper hand in performance, even though treated aggregates mixes showed better moisture resistance properties. © 2014 American Society of Civil Engineers.Item Laboratory Performance of Superpave Mixes for Perpetual Pavements(American Society of Civil Engineers (ASCE), 2017) Priyanka, B.A.; Goutham, G.; Lekha, B.M.; Ravi Shankar, A.U.Long life asphalt pavement, also known as "Perpetual Pavement", is a pavement with design life more than 50 years and needs only periodic surface renewal. It works on the concept of controlling horizontal tensile strain at the bottom of the asphalt layer and vertical compressive strain at the top of the subgrade to a particular limit. This can be achieved by increasing the binder content of the mix over the optimum binder content (OBC) and by increasing the overall pavement thickness. In the present study two Superpave mixes were prepared using conventional binder at OBC (optimum binder mixture [OBM]) and also at 0.5 % extra binder over OBC (rich binder mixture [RBM]) which can be used in Perpetual Pavements. The mixes were tested for indirect tensile (IDT) strength, moisture susceptibility, fatigue and rutting resistance. From the results it was observed that, OBM performed well as compared to RBM. However the fatigue life of RBM was more compared to the OBM and this helps in reducing the horizontal tensile strain at the bottom of the asphalt layer which in turn increases the life of the pavement. © ASCE.Item Experimental Investigation of Black Cotton Soil Stabilized with Lime and Coconut Coir(Springer, 2018) Ravi Shankar, A.U.; Panditharadhya, B.J.; Karishekki, S.; Amulya, S.Expansive soil occurring above the water table undergo volume changes with change in moisture content. In expansive soils, increase in water table causes swelling–shrink behaviour which leads to cracks and differential settlement resulting in several damages to the pavements, canal beds and linings, foundations, buildings, etc. An attempt is made in this paper to study the effect of adding lime-coir fiber on geotechnical properties of black cotton soil. In the present study an effort is made to obtain the optimum dosage of lime for stabilization of black cotton soil abundantly available in Karnataka state of India. The study incorporates investigation of basic geotechnical properties like grain size distribution, specific gravity, consistency limits and engineering properties like Maximum Dry Density (MDD), Optimum Moisture Content (OMC), Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR). Swelling properties have been determined by conducting Free Swell Index (FSI) test. Durability of the soil is studied by conducting wet-dry cycle and freeze-thaw cycles (WD and FT tests). Fatigue test has been conducted to determine the fatigue life of treated and original soil. Further chemical analysis was conducted to determine the chemical composition of untreated and treated soil. The optimum dosage of lime obtained was 4%. The investigations were carried out to study the effect of addition of coir fibers which are obtained from local market to evaluate the extent of modification on MDD, OMC, UCS and CBR of the soil. Maximum improvement in UCS and CBR values are observed when 1% of coir are mixed with the soil. Soil stabilized with Lime-Coir fiber has shown better results when compared to soil stabilized with lime alone. It is concluded that the proportion of 1% coir fiber in a soil is the optimum percentage of materials having maximum soaked CBR value. Hence, this proportion may be economically used in road pavement and embankments. © Springer Nature Singapore Pte Ltd. 2018.Item Investigation on the Effect of Anti Stripping Additives on the Moisture Sensitivity of Bituminous Concrete(Springer Science and Business Media B.V., 2018) Ravi Shankar, A.U.; Goutham, G.; Lekha, B.M.; Carlton-Carew, C.Moisture damage is one of the most common reasons for the premature deterioration of Hot Mix Asphalt (HMA) pavements. Over the years, extensive research has been carried out by scientists and engineers on this subject; however, pavements still succumb to early failure from infiltrating moisture. A very popular method of minimizing the moisture susceptibility of asphalt pavements is by the use of anti-stripping agents. These additives are chemical substances that alter the physicochemical properties of the asphalt by making it more hydrophobic. This study focuses on the effect of anti-stripping agents on the moisture susceptibility of Bituminous Concrete (BC) mixture. The anti-stripping agents used were hydrated lime and Zycosoil. Three mix types were studied, namely: BC mix without additive, BC mix with hydrated lime and BC mix with Zycosoil. Viscosity Grade (VG) 30 bitumen was used in all three groups of samples. Marshall mix design method was adopted and specimens were prepared at bitumen contents 4.5, 5.0, 5.5, 6.0, 6.5 and 7.0% by weight of mixture. Volumetric properties and Marshall characteristics were determined for each specimen, and using them, the Optimum Binder Content for each mixture was obtained. Moisture susceptibility of mixtures was assessed using Tensile Strength Ratio, Retained Stability and Stripping Value. From the experimental results, it is observed that the addition of anti-stripping agents had a significant positive influence on the results of the test properties being evaluated in each test. © 2018, Springer International Publishing AG.Item Mechanical properties of pavement quality concrete with secondary aluminium dross as partial replacement for ordinary portland cement(Institute of Physics Publishing helen.craven@iop.org, 2018) Panditharadhya, B.J.; Sampath, V.; Mulangi, R.H.; Ravi Shankar, A.U.Innovative method of waste disposal can be through utilizing them in concrete production as a filler material or pozzolana. Aluminium dross is a by-product obtained from the aluminium re-smelting process. Aluminium waste is processed in rotary kilns to recover the metal and residual salt cake is sent to landfills. The present study investigates the utilization of secondary aluminium dross as a binder in producing the concrete. It is observed that the initial setting time of the cement paste increases and final setting time decreases with varying percentages of Aluminium dross replacement. This property makes it suitable for hot weather conditions. It was replaced in 5, 10, 15 and 20% of the weight of the cement and optimum dosage is found to be 15 %. The mechanical properties like Compression strength, split tensile strength, flexural strength and water absorption of the M40 grade concrete were determined. It is observed that up to 15% replacement of cement by secondary aluminium dross is giving better results comparable with the conventional concrete. Results show that the Aluminium dross can be replaced as supplementary cementitious material in concrete with no compromise in the mechanical properties of the concrete. © Published under licence by IOP Publishing Ltd.Item Durability Studies on the Lateritic Soil Stabilized with GGBS and Alkali Solutions(American Society of Civil Engineers (ASCE) onlinejls@asce.org 1801 Alexander Bell DriveGEO Reston VA 20191 Alabama, 2019) Amulya, S.; Ravi Shankar, A.U.; Panditharadhya, B.J.In order to use the locally available lateritic soil as a base course for pavement construction, the engineering properties of the soil need to be enhanced. Hence, the experimental investigation of the lateritic soil stabilized with the ground granulated blast furnace slag (GGBS) and combination of alkali solutions such as sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) has been conducted. The various parameters which affect the properties of the soil like binder (GGBS) content, sodium oxide (Na2O) dosage, silica modulus (Ms), and water to binder ratio (w/b) are considered. In the present investigation, the GGBS content of 25%, Na2O of 6%, Ms of 0.5, and w/b of 0.25 are chosen. The Atterberg's limits, standard and modified proctor compaction tests, unconfined compressive strength (UCS), and durability tests were conducted on the stabilized soil. The UCS of 28 days cured and stabilized samples at standard and modified proctor densities is showing 775% and 580% increase with respect to natural soil and 98% and 142% increase with respect to 0 days cured samples respectively. The chosen combination of soil mixture passes all 12 cycles of wetting and drying (WD) and freeze and thaw (FT) with weight loss of 5.2% and 1% at standard proctor density and 8% and 2.5% at modified proctor density respectively after 7 days of curing. © 2019 American Society of Civil Engineers.Item Performance of Concrete Mix with Secondary Aluminium Dross as a Partial Replacement for Portland Pozzolana Cement(American Society of Civil Engineers (ASCE) onlinejls@asce.org 1801 Alexander Bell DriveGEO Reston VA 20191 Alabama, 2019) Panditharadhya, B.J.; Mulangi, R.H.; Ravi Shankar, A.U.; Amulya, S.The safety to our ecosystem can be assured by making use of many industrial wastes in a sustainable manner. Recycling and reutilisation of industrial waste and by-products is of high importance in cement and concrete industry. In view of rapid infrastructure growth, there is an emerging need for development of cementitious materials or fillers either to replace cement or fine aggregate for stable growth. One of such industrial wastes is secondary aluminium dross. In this paper, an attempt has been made to study the mechanical properties of concrete incorporated with secondary aluminium dross. Portland pozzolana cement has been partially replaced by secondary aluminium dross in various proportions like 5, 10, 15, and 20% to study the mechanical properties such as compressive strength, split tensile strength, flexural strength, water absorption. It is observed that up to 15% replacement of cement by secondary aluminium dross is giving better results comparable with the conventional concrete. Also, the increase in initial setting time is observed with increase in percentage replacement of aluminium dross in the concrete which can make it preferable in case of hot weather conditions wherein the concreting for the roads has to be done in an open environment. From the overall study, it can be concluded that the concrete incorporated with secondary aluminium dross can be used for making pavement quality concrete that can sustain low traffic volume or it can be considered for rural roads. © 2019 American Society of Civil Engineers.Item Assessment of Impact of Roadside Bus-Stops on Capacity of Urban Divided Roads Using Microscopic Simulation Model(Springer Science and Business Media Deutschland GmbH, 2022) Raj, P.; Asaithambi, G.; Ravi Shankar, A.U.In developing countries, traffic congestion is not only due to substantial vehicular growth but also due to many roadside activities which affects the performance of roads. Among the various roadside activities, the presence of bus-stops has a significant influence on capacity of roads as the demand of public transport buses in urban areas of developing countries is relatively high. Researchers have attempted to study the impact of bus-stops on traffic flow characteristics. However, limited attempts have been made to study the influence of bus-stops on capacity using simulation models under mixed traffic. Thus, this study aims to assess the impact of roadside bus-stops on capacity of roads using a microscopic simulation model developed specifically for urban divided roads. The validated model was then applied to study the impact of bus-stop on capacity of urban roads. The percentage reduction in capacity due to the influence of bus-stop was obtained by performing sensitivity analysis by varying bus proportion. This study finds interesting applications in developing standards related to capacity estimation and reduction due to side frictions in Indian traffic. © 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.