Browsing by Author "Ravi Shankar, A.U."

Now showing 1 - 20 of 62

A Study on Elastic Deformation Behavior of Steel Fiber-Reinforced Concrete for Pavements
(Springer, 2019) Chandrashekar, A.; Palankar, N.; Durga Prashanth, L.; Mithun, B.M.; Ravi Shankar, A.U.
The present study discusses the experimental investigation of steel fiber-reinforced concrete slabs on ground under wheel load with the objective of understanding the stress behavior when subjected to central and edge wheel loading. The steel fiber-reinforced fly ash concrete slabs of 900 mm × 900 mm, 150 mm thickness were investigated in this study. Strain gauges and data acquisition system were used to measure the strains at the center and the edge of the slab under the action of the load. The load versus strain relationship under central and edge loading for reference concrete and steel fiber fly ash concrete showed a linear variation even up to the pressure of 2.5 MPa, which is much beyond the conventional tyre inflation pressure of 0.8 MPa. The load versus strain graphs clearly signify the higher modulus of elasticity of fly ash steel fiber-reinforced concrete. The stresses were calculated using IITRIGID software and ANSYS software and were found matching significantly. The value of modulus of elasticity of fly ash steel fiber-reinforced concrete (FS) using ANSYS model for experimental values of load and strains measured was approximated to 34,000 N/mm2 and was found to closely match with the experimentally obtained modulus of elasticity. No significant effect of Poisson’s ratio of concrete on load–strain characteristics was observed within the range 0.15–0.2 of concrete. © 2019, The Institution of Engineers (India).
A study on initial setting time and the mechanical properties of AASC using the PS ball as fine aggregate
(Springer, 2019) Talkeri, A.H.; Ravi Shankar, A.U.
India is the second largest producer of cement in the world with an annual production of 455 Million Tonnes (MT) which is expected to reach up to 550MT by 2020. In India, the increased demand for cement in the construction industry is required to meet the needs of infrastructure development. However, the production of Portland cement releases significant amounts of CO2 to the atmosphere. Therefore, it is necessary to look for sustainable solutions for concrete production by the use of supplementary cementitious materials. The alternative replacement for Ordinary Portland Cement (OPC) can be Ground Granulated Blast Furnace Slag (GGBS), Fly-ash, Silica fume, Rice-husk ash, which is the various industrial by-products. In this present work, an attempt was made to develop Alkali Activated Slag Concrete (AASC) using Precious Slag (PS) ball as fine aggregate. The development of AASC was made with GGBS as the principal binder. Mixes were developed with binder content 443 kg/m3, Sodium Silicate (SS)/Sodium Hydroxide (SH) ratio of 1 and their performance when exposed to ambient temperature were studied. Alkali binder ratio (0.3) with 8, 10, 12 and 14M NaOH was selected for all the AASC mixes. The test results showed that the slump values for the different mixes satisfying the MoRTH guidelines for concrete pavements. The AASC mixes have higher compressive strength ranging between 41–64 MPa. The fatigue life of the AASC mix was has improved by the addition of PS ball, at the higher concentration of NaOH. © 2019, Chinese Society of Pavement Engineering. Production and hosting by Springer Nature.
A study on the effect of rejuvenators in reclaimed asphalt pavement based stone mastic asphalt mixes
(Springer, 2019) Durga Prashanth, L.; Palankar, N.; Ravi Shankar, A.U.
The present paper focuses on the behavior of Stone Mastic Asphalt (SMA) mixes incorporating rejuvenated Reclaimed Asphalt Pavement (RAP) materials. The RAP materials were tested for its physical properties and later were rejuvenated using various rejuvenators such as waste cooking oil, waste engine oil and shredded plastics. The rejuvenated RAP materials were incorporated in the SMA mixes at various replacement levels i.e. 0%, 30%, 50% and 70% (by weight). Various binder properties such as viscosity, rheological properties and chemical composition were evaluated for the aged and rejuvenated material. The rejuvenators were incorporated at different dosage levels i.e. 2%, 4% and 6% (by weight of binder). The optimal rejuvenation dosage for each type of rejuvenator was identified and mix design for the SMA was optimized for evaluating its physical and mechanical properties. Based on the results, the optimum rejuvenator dosage was identified at 6% for waste cooking oil and waste engine oil, while 2% for shredded plastics. It was observed that the addition of rejuvenators improved the performance of RAP based SMA mixes. © 2019, Chinese Society of Pavement Engineering. Production and hosting by Springer Nature.
Air-cured Alkali activated binders for concrete pavements
(Chinese Society of Pavement Engineering, 2015) Palankar, N.; Ravi Shankar, A.U.; Mithun, B.M.
The present study focuses on the possibility of use of alkali activatedbinders for use in concrete pavements. Alkali Activated Slag Concrete (AASC) and Alkali Activated Slag Fly ash Concrete (AASFC) are prepared and the properties are compared with Ordinary Portland Cement Concrete (OPCC). The Ground Granulated Blast FurnaceSlag (GGBFS) and Fly Ash (FA) are blended in the ratios 100:0, 75:25, 50:50 and 25:75 as binder and activated using strong alkaline solution. Trial mixes are carried out to identify the optimal Activator Modulus (Ms) for each combination of GGBFS and FA. The mix design for the optimal activator modulus is optimised to achieve sufficient strength for Pavement Quality Concrete (PQC) and the fresh and mechanical properties are studied in detail. The results indicate the properties of AASC and AASFC are similar or slightly better than conventional OPCC and satisfy the minimum strength requirements for concrete pavements. The application of alkali activated binders will minimise the environmental hazards occurring from augmented OPC production, along with effective utilisation of industrial waste materials and conservation of natural resources. © Chinese Society of Pavement Engineering.
Alkali Activated Black Cotton Soil with Partial Replacement of Class F Fly Ash and Areca Nut Fiber Reinforcement
(Springer Science and Business Media Deutschland GmbH, 2023) Chethan, B.A.; Ravi Shankar, A.U.; Chinnabhandar, R.K.; Kumar, D.H.
Alkali activation has received great attention for improving the soil properties with suitable precursor materials. Industrial byproduct class F fly ash was suitably utilized to improve Black Cotton (BC) soil properties along with ordinary Portland cement by various researchers. However, the CO2 emission associated with cement production has enforced the evaluation of alternative binders. Laboratory investigations were conducted on BC soil by admixing various fly ash dosages (0â€“50%) and reinforcing the mix with 0.5% areca nut fiber. Alkali activator solution prepared using 8 molar sodium hydroxide solution (SH) and sodium silicate solution (SS) at 1.5 SS/SH ratio showed significant improvement in Unconfined Compressive Strength (UCS) of stabilized BC soil on 7 and 28Â days curing. The reinforcement was effective in improving the flexural strength of stabilized mixes. Exorbitant unsoaked California Bearing Ratio (CBR) values were observed on 28Â days of curing. However, the samples could retain low soaked CBR values despite reinforcement. Scanning Electron Microscope (SEM) images showed the reduction of shrinkage cracks and strong bonding of fibers in the stabilized mix. X-Ray Diffraction (XRD) patterns evidenced the formation of various hydration products due to the alkali reaction, which resulted in the high strength gain of mixes at ambient temperature curing. The leaching of mineral constituents from the set mix lead to the failure of durability samples. Due to nondurability, the alkali activation with a selected precursor cannot suit pavement materials requirements. Â© 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Alkali activated slag-fly ash concrete incorporating precious slag as fine aggregate for rigid pavements
(Chang'an University, 2022) Talkeri, A.; Ravi Shankar, A.U.
This study aims to develop the alkali activated slag-fly ash concrete (AASFC) using precious slag (PS) ball as the fine aggregate. The slag-fly ash proportion, sodium silicate/sodium hydroxide (SS/SH) ratio and sodium hydroxide concentration are the prime variables. The fresh concrete properties like workability, setting time and the hardened concrete properties of AASFC developed under ambient curing were analyzed and similar way by replacing with fly ash (FA). The sodium hydroxide concentration of 8 M, 10 M and 12 M, SS/SH ratio of 1.0, 1.5 and 2.0, alkaline liquid to binder ratio of 0.35 and variation in slag-fly ash proportion as major inputs for mix design. The test results showed that, the fresh state of AASFC blend has a shorter setting time of 12–16 min, because of calcium mineral from the FA, the workability and setting time of AASFC mix was enhanced by the addition of the tri-sodium phosphate as a retarder. At the higher SS/SH extent, the workability and setting time exaggerated, whereas the increased FA content and sodium hydroxide concentration had a greater influence on the fresh state of concrete. Also, the sodium hydroxide concentration, SS/SH ratio and slag-fly ash proportion are the most inducing parameters on the workability, setting time and strength parameters of AASFC. © 2021 The Authors
Areca Fiber Reinforced Alkali-Activated Black Cotton Soil Using Class F Fly Ash and Limestone Powder for Pavements
(Springer Science and Business Media Deutschland GmbH, 2022) Chethan, B.A.; Ravi Shankar, A.U.
Alkali activation has gained importance in place of cement treatment in construction due to reduced CO2 emissions. The precursors that are rich in silica, alumina, and calcium can be used for soil stabilization with a suitable alkali solution. In this investigation, 0â€“45% class F fly ash with a constant 5% limestone powder was used to stabilize black cotton soil. These mixes were reinforced with 0.5% areca fibers and stabilized using the alkali solution. Alkali solution was prepared using 8 molar NaOH solution and Na2SiO3 solution with Na2SiO3/NaOH of 1.5. The use of limestone powder has favoured the quick UCS gain on 3Â days of room temperature curing. Fiber reinforcement has shown a significant influence on flexural strength and fatigue life improvement. Areca fibers reinforcement has resulted in enormous resistance to plunger penetration during the unsoaked CBR test. However, on further 4Â days of soaking, samples lost the bonding and exhibited low CBR. The SEM images showed the compact microstructure of the set mix. The formation of cementitious products is evident from the XRD micrograms due to the dissolution of silica, alumina, calcium, and other compounds by the alkali solution. When subjected to wettingâ€“drying and freezingâ€“thawing durability tests, the set mixes were failed due to leaching of mineral constituents and further breaking of soil structure. Even though stabilized specimens exhibited significant strength improvement in dry conditions, they are unsuitable in wet conditions. Â© 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.
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. Â© 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Comparison of Stone Matrix Asphalt mixtures with polymer-modified bitumen and shredded waste plastics
(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2016) Goutham, G.; Lekha, B.M.; Krishna, G.; Ravi Shankar, A.U.
Stone Matrix Asphalt (SMA) is a gap-graded bituminous mixture characterised with its improved rut resistance and durability. It has comparatively higher proportion of coarse aggregates and binder mastic with bituminous binder and mineral filler. Drain down of mastic content at various stages of construction is a common issue with SMA, and generally, some fibre additives are used to stabilise the mixture or a modified bitumen is used as the binder material. In this study, shredded waste plastics (SWP) are used instead of other stabilising additives, to prepare SMA mixtures with conventional viscosity graded (VG) 30 bitumen. Mixtures were prepared with four different levels of SWP content, and another mixture without any stabilisers was also prepared using polymer-modified bitumen (PMB). Specimens were prepared in superpave gyratory compactor (SGC) for all mixtures at different bitumen contents to determine volumetric and Marshall properties, and optimum bitumen content (OBC) was calculated for each mixture. Tensile strength, moisture susceptibility, rutting resistance and fatigue behaviour were also determined for all mixtures at corresponding OBC. From the available results, the optimum level of SWP in SMA mixture was determined as 8% by weight of bitumen. The study showed that even though mixture with PMB performed the best, SMA with 8% SWP provided comparable results. Based on the present investigation, waste plastic in suitable dosage can be recommended in SMA, instead of a stabilising additive. © 2015 Informa UK Limited, trading as Taylor & Francis Group.
Comparison of Volumetric Properties and Stability of Bituminous Mixes with Shredded Waste Plastic
(Springer Science and Business Media Deutschland GmbH, 2024) Otageri, S.; Kumar, D.H.; Mulangi, R.H.; Ravi Shankar, A.U.
Sustainable road construction has been increasingly gaining much recognition due to the unendurable conventional pavements. To avoid adverse effects on the environment, ecofriendly road construction is taking attention these days. Waste plastic generated will end up in landfills, incinerated, or recycled. However, in India per capita, plastic consumption is quite less in comparison to the global per capita consumption of plastic. So, the eco-design of asphalt mixture utilizing shredded waste plastic is adopted to recycle and reuse the shredded waste plastic in flexible pavements. This paper compared the volumetric properties and stability of asphalt mixes prepared with shredded waste plastic. Conventional bitumen such as VG30, VG40, and polymer-modified bitumen PMB40 for two aggregate gradations with a Nominal Maximum Aggregate Size (NMAS) of 25Â mm and 19Â mm abbreviated as G1 and G2, respectively, was used to prepare the mixes. Three dosages of waste plastic (4%, 6%, and 8%) to the weight of optimum binder content (OBC) were added, by dry mixing method, to VG30 bituminous mixes. A total of 12 different types of mixes were prepared and tested for volumetric properties and stability. It was observed that with the increase in dosage of waste plastic, volumetric properties such as air void (AV) and Voids in Mineral Aggregate (VMA) increased while the density decreased. The results showed that incorporating shredded waste plastic in the mix improved the Marshall Stability (MS) and stiffness of the mix which is also environmentally friendly. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
Determination of Factors Affecting the Willingness to Pay Elicited by the Contingent Valuation Payment Card Method Using Structural Equation Modelling
(Springer Science and Business Media Deutschland GmbH, 2024) Sumayya Naznin, P.H.S.; Katrawath, D.; Sabu, R.M.; Ravi Shankar, A.U.
The global road traffic accident statistics recall the urgent need for worldwide road safety improvement. The resource allocation towards the road safety infrastructures requires a cost-benefit analysis, which necessitates the road accident cost estimation. The willingness to pay (WTP) elicitation by contingent valuation using the pavement card format is a prominent approach to determine the value of statistical life (VSL) as well as the accident cost. The WTP of road users depends upon various factors like socio-economic characteristics, risk perception, and good driving behaviour. Even though the said factors seem to influence the WTP evidently, the extent to which each factor influence is ambiguous and is population dependent. Structural equation modelling (SEM) is a powerful tool to determine the factors affecting WTP. The study assesses the impact of above said factors on the WTP of the respondents of Ernakulam City, Kerala, India. The impact of all the factors was found to be positive and significant at 0.001 level. Among the socio-economic characteristics, the four-wheeler ownership (standard parameter estimate, Î²â€‰=â€‰0.63) is found to strongly influence the WTP followed by a high household income level (Î²â€‰=â€‰0.45). Among the good driving behaviour characteristics, never drink and drive behaviour (Î²â€‰=â€‰0.96) shows the highest influence followed by never overspeeding (Î²â€‰=â€‰0.88). Those who perceived their accident risk to be average or above average were willing to pay more for road safety than others. Considering the risk perception factors, respondents whose family or close friends had a previous experience with an accident had a magnitude parameter estimate (Î²â€‰=â€‰0.77) higher than a personally experienced accident. Though the socio-economic characteristics were found to be strongly influencing the WTP followed by risk perception and good driving behaviour, the individual parameter estimates show that never drink and drive behaviour influences the WTP to the maximum. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
Durability studies on eco-friendly concrete mixes incorporating steel slag as coarse aggregates
(Elsevier Ltd, 2016) Palankar, N.; Ravi Shankar, A.U.; Mithun, B.M.
The present study discusses the durability performance of alkali activated concrete mixes containing steel slag as coarse aggregates. Steel slag aggregates, a waste product obtained from iron and steel industry are incorporated as coarse aggregates in alkali activated slag concrete (AASC) and alkali activated slag fly ash concrete (AASFC) by replacing traditional natural aggregates. The mix design for AASC and AASFC mixes are optimised to obtain sufficient strength for structural purposes and then steel slag coarse aggregates are incorporated at different replacement levels (0%, 50% and 100% by volume of total coarse aggregate content). Durability properties such as long term ageing performance, water absorption, volume of permeable voids, resistance to sulphuric acid attack and resistance to magnesium sulphate attack are studied in detail and compared with conventional Ordinary Portland Cement Concrete (OPCC). The ecological and economical analysis of concrete mixes is also carried out. It was found that the AASC and AASFC mixes displayed better durability performance as compared to OPCC. The inclusion of steel slag aggregates slightly reduced the durability performance of AASC and AASFC mixes. The AASC and AASFC with steel slag aggregates displayed lower energy requirement and lower production cost as compared to OPCC, thus proving it to be eco-friendly. © 2016 Elsevier Ltd. All rights reserved.
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. Â© 2019 American Society of Civil Engineers.
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.
Effect of curbside bus stops on passenger car units and capacity in disordered traffic using simulation model
(Taylor and Francis Ltd., 2022) Raj, P.; Asaithambi, G.; Ravi Shankar, A.U.
Representation of traffic in terms of Passenger Car Unit (PCU) is imperative to estimate capacity in disordered traffic. Many studies have been conducted on investigation of impacts of traffic and geometric conditions on traffic characteristics and PCUs. However, the sensitivity of PCUs due to roadside frictions are not adequately studied. To address this gap, this study aims to estimate PCU values for vehicles under the influence of curbside bus stop, which is the most common roadside friction in developing countries. Lack of space for providing exclusive bus bays and higher demand for public transport buses in urban roads justify the need for this study. Methodology of this study involves development and validation of a microscopic simulation model to quantify the impact of curbside bus stop on PCU as well as capacity. The results indicate the significant differences in PCU values due to the presence of curbside bus stop with varying traffic volume and composition. © 2020 Informa UK Limited, trading as Taylor & Francis Group.
Effect of Electrolyte Lignin and Fly Ash in Stabilizing Black Cotton Soil
(Springer US, 2015) Lekha, B.M.; Goutham, G.; Ravi Shankar, A.U.
Subgrade is one of the important layers of any pavement. It must be able to support loads transmitted from pavement structure without excessive deformation under adverse climatic and traffic conditions. In this investigation, laboratory studies were carried out to evaluate the influence of a commercial electrolyte lignin stabilizer (ELS), fly ash (FA) and a combination of both, on black cotton (BC) soil procured from North Karnataka region in India. Basic geotechnical and engineering properties like unconfined compressive strength (UCS), California bearing ratio (CBR), etc. were determined for both untreated and treated soil. Dynamic repeated load test was conducted to examine the fatigue behaviour of the soil. Durability of the soil was checked by wet-dry (WD) and freeze-thaw (FT) cycle tests, and swelling properties by free swell index test. From the studies, it was observed that consistency limits, dry density, UCS and CBR values were improved for treated soil, with curing periods of 1, 7 and 28 days. Weight loss in FT test was less than 14 % for 12 cycles, which ensures that the stabilized soil has become durable. But none of the samples were observed to be withstanding above five cycles in wet-dry test. Soil stabilized with ELS and FA showed better results compared to soil with only ELS. Swelling was reduced to a great extent with 28 days curing period for the former one. From the experimental results, it can be concluded that this chemical can be used as a stabilizer for existing BC soil in site to enhance its subgrade strength. © 2015, Springer New York.
Effect of Flash Flood and Weather Changes on Unconfined Compressive Strength of Cement- and Fly Ash-Stabilized Black Cotton Soil Used as Road Materials
(Springer, 2023) Chethan, B.A.; Ravi Shankar, A.U.
Stabilized soil naturally undergoes variation in moisture content and temperature during seasonal weather changes. In this investigation, the influence of these weather changes on unconfined compressive strength (UCS) of black cotton (BC) soil stabilized with ordinary Portland cement (43 grade) and class F fly ash was studied. Cement dosage was varied from 3 to 10%, along with different combined dosages of (cement + fly ash) (where fly ash < 32%) for stabilizing various mixes. The UCS specimens were cured for 0 (immediately after preparation) 3, 7, 28, 60, and 90 days in a desiccator and subsequently submerged for 24 h in water to ensure saturation. The flash flood effect was evaluated in terms of strength reduction by correlating UCS of saturated specimens (UCSs) with UCS of desiccator-cured specimens. The stabilized materials’ resistance to wetting–drying (WD), freezing–thawing (FT) durability tests and subsequent UCS retained over time were determined. The UCS values increased substantially at higher cement and fly ash contents and with the curing period, whereas a notable reduction in UCSs values was observed for saturated samples. However, the samples with high cement and fly ash contents exhibited low moisture susceptibility with lesser strength reduction. The UCS and UCSs values are linearly correlated with R2 values > 0.9. All the specimens were intact with improved volume stability at higher cement and fly ash dosages during saturation and drying. Mixes with high cement and fly ash dosages shown improved resistance to WD cycles, whereas at a low dosage, most of the mixes failed during the second wetting cycle due to a drastic absorption of water after the first drying cycle. All FT specimens were intact with considerable strength retained after 12 cycles exhibiting a minimal mass loss. The formation of hydration products has justified the strength gain as observed from scanning electron microscope (SEM) images, energy dispersive X-Ray analysis (EDAX), and X-ray diffraction (XRD) plots. © 2021, The Author(s), under exclusive licence to Chinese Society of Pavement Engineering.
Effect of gradation and waste plastic on performance of stone matrix asphalt (SMA)
(IAEME Publication iaemedu@gmail.com, 2018) Mithanthaya, I.R.; Marathe, S.; Ravi Shankar, A.U.
Stone Matrix Asphalt (SMA) is a gap-graded blend which possesses a high deliberation coarse aggregate framework with stone-to-stone contact along with a high binder content which adds flexibility and durability of the mix. The SMA is associate with the drain down of binder during mixing, transporting and laying of the mix. In sequence to prevent this and to improve the mix characteristics, it was proposed to study the properties of SMA by modifying it by adding waste plastics. Hence, stability, flow value, percentage drain down, and rutting characteristics of SMA mixes having different proportions of waste plastic were studied. Initially, it was decided on the basis of highest value of bulk density i.e., Chinese and Indian gradation of aggregates were selected. The Marshall Tests were conducted to find out Optimum Bitumen Content (OBC) with different proportions of bitumen and plastic content. Further, the drain down tests and rutting test using Immersion Wheel Tracking Device were also conducted on the SMA specimens at Optimum Plastic Content (OPC). From Marshall Test, for the SMA of Chinese gradation, OPC was found to be 8.0%, and that for Indian gradation it was 6.0% plastic content, respectively. Addition of waste plastic to the SMA leads to a decrease in the drain down value and satisfies the condition for both the gradations. Also, the rutting intensity was observed to be 42 per-cent greater for Indian gradation, when contrasted to that of Chinese gradation. Overall, Chinese gradation has shown the better results than the Indian gradation. © IAEME Publication.
Estimation and Comparison of Saturation Flow at Signalized Intersection in Mixed Traffic Condition
(Springer Science and Business Media Deutschland GmbH, 2022) Mahapatra, M.J.; Advani, M.; Ravi Shankar, A.U.
Signalized intersections are the important part of urban road network. Capacity of signalized intersections has significant role in capacity of overall road network in an area. Accordingly, capacity estimation of signalized intersection and therefore the estimation of saturation flow values become an important aspect especially for Indian roads due to the presence of different types of vehicles and space sharing-based vehicular movement. This study extracts the saturation flow from the field data captured through videography and compares it with the saturation flow values estimated by various methods available in literature. Data have been collected at two signalized intersections; first one is a four-legged intersection, and other one is three-legged intersection. Approach width of all arms of both intersections ranges from 7.6 to 10.3Â m. Both intersections are located on the main arterial road of Delhi, India, and at the distance of 1.1Â km without any obstructions in-between. Saturation flow has been estimated through existing methods available in literature and compared with the developed model in this study. Proposed model indicates that with the increased width, saturation flow values also increase. Values estimated are closer to values obtained by Websterâ€™s method. Â© 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Evaluation of lateritic soil stabilized with Arecanut coir for low volume pavements
(Elsevier Ltd, 2015) Lekha, B.M.; Goutham, G.; Ravi Shankar, A.U.
Soil stabilization is a common method used by engineers and designers to enhance the properties of soil with different stabilizers. From ancient times, usage of natural fiber in soil as reinforcement is an effective technology adopted. This paper presents the effect of including randomly spaced Arecanut coir to the soil mix. The engineering properties and bearing capacity of a soil get enhanced by stabilizing it with Arecanut coir and a binding material (cement). The information available on experiments and research on the behavior of soil cement mixtures were collected and a few studies conducted on fiber reinforcement were referred. The current study mainly focuses on the durability test and physical evaluation of soil cement mixtures reinforced with Arecanut coir. Coir content was varied from 0.2% to 1% with an increment of 0.2%. For further improvement, a uniform dosage of 3% cement was added to soil. Laboratory tests including the Unconfined Compressive Strength (UCS), California Bearing Ratio (CBR), durability and fatigue behavior, were conducted as per standards. The test results indicated that the improvement in characteristics of the soil cement coir mixtures were functions of coir dosage, soil type and curing days. Durability test satisfied at 1% Arecanut coir with 3% cement. The stress-strain values were determined and damage analysis was conducted for the higher dosage of Arecanut coir using KENPAVE software. From the results it is observed that, the Arecanut coir reinforced cement soil mix can be used for low volume roads (traffic ?1 million standard axles) and few design cases have been discussed. © 2014 Elsevier Ltd.