Faculty Publications
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Item 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.Item 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.Item 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.Item 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.Item Mechanical properties of pavement quality concrete with aluminium industry waste as a binder(Elsevier Ltd, 2023) Panditharadhya, B.J.; Mulangi, R.H.; Ravi Shankar, A.U.Utilizing industrial marginal materials in the production of concrete makes it economical by reducing the cost of cement and reduces the environmental risk associated with Ordinary Portland Cement (OPC) production. Aluminium Dross (AD) is an industrial by-product from aluminium industry obtained during resmelting of aluminium ore in the furnace at high temperatures. Dumping of this waste in landfill makes it difficult to facilitate large area required and causes nuisance to the surrounding environment. Also, it is required to minimize the use of Ordinary Portland Cement (OPC) due to higher energy consumption involved in its production. AD is pre-treated and tested by Toxicity Characteristic Leaching Procedure (TCLP) to check its leachability. In this study, mechanical properties of concrete along with flexural fatigue behaviour are discussed with respect to partial replacement of AD for OPC. Strength properties of concrete at 15% AD replacement is comparable with that of control concrete. Scanning Electron Microscope (SEM) image of the concrete mix with 15% AD is taken to observe minor voids in comparison with the SEM image of normal concrete mix. Flexural fatigue behaviour is evaluated at varying stress levels and found that the concrete with 15% AD is satisfying the requirements to be used as Pavement Quality Concrete. © 2023