Browsing by Author "Raghuram, K.C."

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    Alkali Activated Concrete Mixes with Processed Reclaimed Asphalt Pavement
    (Springer, 2025) Talkeri, H.T.; Sagar, M.H.; Raghuram, K.C.; Hemanth, D.; Kondeti, C.; Preethi, S.
    This study evaluates the feasibility of using processed reclaimed asphalt pavement for alkali-activated slag concrete (AASC) mixes. A novel alkali and alkali-abrasive method is developed to remove the stiff asphalt layer and puncture the asphalt film engulfed in the Reclaimed Asphalt Pavement (RAP) material. The hydrophobic layer of asphaltic aggregate exhibits poor bond characteristics, significantly affecting concrete strength properties. The influence of processing methods on concrete characteristics was investigated and compared with control mixes. Incorporating processed RAP improved the workability properties and cohesiveness of mixes at different sodium hydroxide concentrations. Beneficiation of processed RAP by alkali and alkali-abrasive techniques increased strength characteristics by 20% and 42% respectively compared to control mixes. Processing RAP using the alkali technique improved workability properties slightly, while the alkali-abrasive technique significantly improved fresh and hardened characteristics due to the removal of the stiff asphalt layer. Fatigue test data were analyzed using a two-parametric Weibull distribution for survival probability. The analysis established that fatigue life at various stress levels for AASC with processed RAP can be described using Weibull distribution. Goodness-of-fit tests validated the distribution model for the statistical description of the fatigue life of various mixes. Based on laboratory tests, alkali-activated mixes developed with processed RAP satisfy requirements for pavement-quality concrete. © The Author(s), under exclusive licence to Chinese Society of Pavement Engineering 2025.
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    Soil Stabilization Using Spent Coffee Residue with Geopolymerization Technique
    (Springer Science and Business Media Deutschland GmbH, 2024) Lalfakzual; I Talkeri, H.T.; Raghuram, K.C.; Chiranjeevi, K.
    Spent coffee residue contains a significant amount of biodegradable material and is extremely organic. This study aims to assess the feasibility of blending the soil with spent coffee residue and industrial by-products such as fly ash and slag through a sustainable approach using the geopolymerization technique. Geopolymerization was induced using fly ash (FA) and slag as precursors with sodium hydroxide and sodium silicate as alkaline activators. Modified compaction was investigated to determine the optimum moisture content and bearing strength of the mixes produced. The Taguchi's L-9 orthogonal array served as the foundation for the formulation of all nine geopolymer mixes created herein. In an initial calibration phase, the durability and unconfined compressive strength (UCS) characteristics of a set of nine mixes were utilized for performance evaluation. On the basis of these findings, strength and durability prediction equations were developed. In the prediction phase, the accuracy of the developed model is evaluated with actual test results from trials on the nine mixes. Partial replacement of slag by 20 and 30% with the desired sodium oxide content range between 3 and 5% complied with the standard for subgrade material. Test results indicate stabilized coffee residue might be used as subgrade material rather than being dumped in landfills. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.