http://nopr.niscpr.res.in/handle/123456789/66744 2026-10-09T17:14:28Z 2026-10-09T17:14:28Z Mudgal, Manish Nageshwar, Akash Chouhan, Ramesh Kumar Mudgal, Vedansh Chauhan, Janardan Singh Srivastava, Avanish Kumar http://nopr.niscpr.res.in/handle/123456789/66754 2025-11-11T10:11:19Z 2025-08-01T00:00:00Z

Title: Effect of quick lime addition for improving compressive strength of fly ash based (cement free) geopolymer concrete Authors: Mudgal, Manish; Nageshwar, Akash; Chouhan, Ramesh Kumar; Mudgal, Vedansh; Chauhan, Janardan Singh; Srivastava, Avanish Kumar Abstract: In this current investigation, a comprehensive exploration has been undertaken to advance the development of “Class F” fly ash-based Geopolymeric mortar and concrete, utilizing fly ash that has been sourced from the Satpura Thermal Power Station in Sarni, District Betul, Madhya Pradesh, India. The study has systematically investigated the influence of Quick Lime addition in the formulation of fly ash-based Geopolymeric mortar and concrete, with a particular focus on enhancing compressive strength within the constraints of ambient atmosphere conditions. The Geopolymeric binder has been meticulously crafted using sodium hydroxide and sodium silicate as alkaline activators. Systematic variations of Quick Lime dosages (ranging from 0% to 10% by weight of fly ash) have been introduced, and the ensuing specimens have undergone scrutiny for standard consistency and setting time under ambient temperature curing. The outcomes have underscored a discernible trend wherein the judicious addition of 7 to 9 wt.% calcium oxide (Quick Lime) to the fly ash matrix has precipitated a noteworthy reduction in setting time at room temperature, concurrently manifesting a substantial enhancement in compressive strength for Geopolymeric mortar and concrete formulations. The elucidation of the binder's microstructural phases and their chemical characteristics has been pursued through rigorous analytical methodologies, encompassing X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), and field emission scanning electron microscopy (FE-SEM). Cost analysis has also been conducted for 1m³ of concrete, comparing conventional concrete (M25) and fly ash-based Geopolymer concrete Page(s): 417-424

2025-08-01T00:00:00Z Verma, Rinki Agrahari, Ravinder Kumar Pathak, Krishna Kant Pathak, Virendra http://nopr.niscpr.res.in/handle/123456789/66753 2025-11-11T10:04:11Z 2025-08-01T00:00:00Z

Title: Seismic acceleration amplification factor under fixed and pin supported RC frame building Authors: Verma, Rinki; Agrahari, Ravinder Kumar; Pathak, Krishna Kant; Pathak, Virendra Abstract: Assessing non-structural elements' vulnerability to acceleration has relied on peak horizontal floor acceleration. Given the dynamic nature of structures, estimates for forces acting on elements like mechanical, electrical, or architectural components have been crucial. The amplification factor for these non-structural components has been affected not just by building height but also by the structural support conditions. This study has examined five distinct building models spanning 2, 4, 6, 8, and 10 stories. The models have been analysed using the nonlinear time history analysis method under various near-field Chi-chi earthquake scenarios (ranging from 0.01g to 0.067g, 0.067g to 0.2g, and 0.2g to 0.32g). This analysis has aimed to determine the acceleration amplification factor (Ω), defined as the ratio of peak floor acceleration to peak ground acceleration (PGA), for both fixed and pinned support conditions. A disparity has emerged after comparing the actual acceleration amplification values under fixed and pinned support conditions with those from previous models. While some models have performed adequately under fixed support conditions, others have yielded accurate results under pinned support conditions. Consequently, there has been no singular formula capable of effectively accommodating both support conditions across the varying ranges of ground motion. Page(s): 425-437

2025-08-01T00:00:00Z Athar, Humaira Kadaba, Raghunandan Singh, Lok Pratap Rawat, Pradeep http://nopr.niscpr.res.in/handle/123456789/66752 2025-11-11T10:01:02Z 2025-08-01T00:00:00Z

Title: Enhanced mechanical and durability performance of dry mix concrete made with silica-coated aggregates Authors: Athar, Humaira; Kadaba, Raghunandan; Singh, Lok Pratap; Rawat, Pradeep Abstract: This research work has focused on enhancing the mechanical and durability properties of M40 grade concrete by replacing natural granite coarse aggregates with silica-coated granite aggregates. The mix has been further improved by changing the order of mixing ingredients and by using a mechanically modifying binder. Improvement in the fresh state properties of all the mixes has been observed due to the formation of a lubricating layer over the aggregates as a result of the slurry coating, compared to control concrete. Around 48% increase in 28 days’ compressive strength, 47% enhancement in flexural strength, and 36% in tensile strength have been observed with the modified formulations. Furthermore, the enhanced formulation has lowered the chloride penetration by 20% and water penetration by 80%. The dense interfacial transition zone of scanning electron microscopic images has shown that the use of silica-coated aggregates, along with mechanically modifying the binder and changing the order of mixing, has imparted superior mechanical and durability properties to the concrete compared to conventional methods. Page(s): 438-446

2025-08-01T00:00:00Z Mohan, Keerthana Harikrishna, Pabbisetty http://nopr.niscpr.res.in/handle/123456789/66751 2025-11-11T09:57:27Z 2025-08-01T00:00:00Z

Title: Fully coupled analysis of a floating offshore wind turbine under wind and wave loading Authors: Mohan, Keerthana; Harikrishna, Pabbisetty Abstract: Floating Offshore Wind Turbines (FOWTs) have been exposed to a multi-hazard scenario of wind and wave conditions, which have acted simultaneously. To assess their combined effect on the FOWT and to ensure the safety and stability of the supporting structure, numerous complex loading conditions such as wind-induced aerodynamic loads, wave-induced hydrodynamic loads, and the dynamics of the supporting structure have been considered. In this study, a comprehensive time-domain analysis of the NREL 5 MW Reference Wind Turbine (RWT) supported on the OC4 DeepCwind semi-submersible has been carried out under both operating and parked conditions using the aero-hydroservo- elastic tool OpenFAST. The operating condition of the FOWT has included simulations at various wind speeds from cut-in to cut-out wind speed, with co-existing wave parameters for each wind speed. Based on the fully coupled analysis of the FOWT under simultaneously acting wind and wave conditions, the principal parameters required for the structural design of the rotor and supporting structure such as blade-root moments and tower fore-aft/overturning moments have been presented, alongside the key aspects of environment-structure interactions Page(s): 447-461

2025-08-01T00:00:00Z