Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
7 results
Search Results
Item Utilization of Ferrochrome and Recycled Concrete Aggregates for Sustainable Pavement Base Layers—A Laboratory Study(Springer Science and Business Media Deutschland GmbH, 2025) Chiranjeevi, K.; Kumar, D.H.; Yatish, R.G.; Talkeri, H.T.; Mulangi, R.H.; Ravi Shankar, A.U.The paramount importance of incorporating alternative aggregates cannot be overstated, as it plays a pivotal role in resource conservation, sustainability promotion, and efficient waste management. This study focuses on the utilization of ferrochrome aggregate (FCA) and recycled concrete aggregate (RCA) within cement-treated base layers, aiming to entirely substitute natural coarse aggregate (NCA). The research meticulously fabricated cement-treated recycled and ferrochrome aggregate (CTRFA) samples with cement contents of 3, 5, and 7%. These specimens incorporated varying blends of RCA and FCA, ranging from 0 to 100%. In this investigation, strength properties such as unconfined compressive strength (UCS), flexural strength, elastic modulus, and indirect tensile strength (ITS) were performed alongside durability. The experimental results indicated that the cement content exerted a more pronounced influence on both strength and durability. The CTRFA mixes containing 50% RCA, 50% FCA, and 5% cement meet IRC 37 2018 strength and durability standards and can be used as a base layer for flexible pavement instead of conventional cement-treated base (CTB). © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.Item Strength and shrinkage properties of heat-cured fly ash-based geopolymer mortars containing fine recycled concrete aggregate(ASTM International, 2020) Saha, S.; C, C.Geopolymer has obtained significant importance as an alternative eco-friendly binder material for ordinary portland cement (OPC) as it can be produced from the reaction between the industrial by-product materials rich in alumina, silica, and alkaline solutions. Therefore, usage of geopolymer effectively in the construction industry will help to reduce the consumption of a huge quantity of natural resources for the energy processes required for the production of OPC. It is also one of important solution to control carbon dioxides emission by the usage of OPC. On the other hand, using construction and demolition waste (C&DW) as the source of recycled aggregates in construction industry helps to reduce the huge consumption of natural aggregates and protect the environment from the disturbances caused by the unorganized dumping of C&DW. In this study, an attempt has been madeto produce fly ash (FA)-based geopolymer mortar mixes using C&DW effectively as fine aggregates partially. The effects of recycled fine aggregates (RFA), the ratio of alkaline liquid (AL) to FA, and duration of heat curing on the properties of the produced geo-polymer mortar mixes have been discussed in this article. To determine the influence of RFA on the strength and volume change behavior of mixes, natural fine aggregates were replaced by RFA at 0, 10, 20, 30, 40, and 50 % by mass. The AL/FA ratio was adopted as 0.4 and 0.6. Higher compressive strength was observed for most of the mortar mixes having RFA up to 20 %, and higher drying shrinkage value was found for the mixes with higher RFA content. Scanning electron microscopy (SEM) images were also studied for knowledge about the signature of the formed structures in the mortar mixes, which were observed having higher strength. © © 2019 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.Item Optimisation of recycled concrete aggregates for cement-treated bases by response surface method(Taylor and Francis Ltd., 2023) Chiranjeevi, K.; Kumar, D.H.; Srinivasa, A.S.; Ravi Shankar, A.U.Sustainability is a primary concern that needs to be addressed since infrastructure development requires significant natural resources. Using Recycled Concrete Aggregates (RCA) for road construction has numerous benefits in saving natural resources and the environment. In the present investigation, the demolition waste is being used for road construction, partially/fully replacing natural aggregates. The Cement Treated Recycled Concrete Aggregate (CTRCA) specimens were prepared at 3%, 5%, and 7% cement with various blends of RCA and Natural Coarse Aggregates (NCA) ranging from 0 to 100%. The strength characteristics in terms of Unconfined Compressive Strength (UCS), Flexural Strength (FS), Elastic Modulus, Indirect Tensile Strength (ITS) and durability tests were conducted on cured samples. Microstructural analysis using Scanning Electronic Microscope (SEM) revealed that the pores and cracks in the old mortar have a detrimental influence on the mechanical properties of CTRCA mixes. However, Energy Dispersive Spectroscopy (EDS) and durability tests have shown positive results. The Response Surface Method (RSM) was utilised to optimise the RCA and cement content in CTRCA mixes. The research resulted in the maximum possible RCA of up to 70% with a cement content of 5.8%, which met the Indian Road Congress (IRC) specifications for Cement Treated Bases (CTB). © 2023 Informa UK Limited, trading as Taylor & Francis Group.Item Laboratory investigation on cement-treated recycled concrete aggregate bases for flexible pavements(Elsevier Ltd, 2023) Chiranjeevi, K.; Hemanth Kumar, D.; Yathish, R.G.; Ravi Shankar, A.U.India's economy is progressing fast, and many infrastructure development programs are going on. Especially the road network expansion is going on many folds. As a result, natural coarse aggregates are getting depleted, which has an impact on environmental sustainability. Utilizing the resources from the many aged and demolished structures will be cost-effective and solve the disposal problem of these wastes. India's government insists on using marginal material, demolished waste, or recycled aggregates as alternative materials for road construction. New codes developed by IRC and MoRTH recommend Cement Treated Bases (CTB) and Cement Treated Sub-Bases for pavement lower layers. In light of this, the present study attempts to utilize Recycled Concrete Aggregates (RCA) obtained from construction and demolition (C&D) waste in the CTB. The efficiency of RCA was checked at various replacement levels ranging from 0% to 100% with cement stabilization of 3%, 5%, and 7%. The strength properties like Unconfined Compressive Strength (UCS), Flexural Strength and durability were evaluated. The microstructural characteristics and elemental analysis of the cement treated recycled concrete aggregate mixtures were examined. The research yielded the highest potential RCA of up to 50% with a cement content of 5%, meeting the Indian Road Congress (IRC) criteria for CTB. © 2023Item Utilization of recycled concrete aggregates for pavement base courses – A detailed laboratory study(Elsevier Ltd, 2024) Chiranjeevi, K.; R G, Y.; Kumar, D.H.; Mulangi, R.H.; Ravi Shankar, A.U.R.Pavement construction and maintenance have become prevalent globally due to increasing traffic volumes and higher vehicular axle weights, driven by population growth and technological advancements. However, the extensive reliance on natural resources raises concerns about their long-term availability and sustainability. An emerging trend in construction involves the application of alternative materials, such as demolished waste and industrial by-products, as substitutes for natural materials like aggregates. This study examined strength properties, including unconfined compressive strength (UCS), flexural strength, elastic modulus, indirect tensile strength (ITS) and the performance aspects of durability, shrinkage, and fatigue. Cement stabilized recycled concrete aggregate (CSRCA) mixes were prepared by varying the percentage of natural coarse aggregate (NCA) and recycled concrete aggregate (RCA) from 0% to 100% and cement content from 3% to 7%. The experimental findings demonstrated that the cement content had a more significant impact on the strength and performance characteristics of CSRCA mixes than RCA content. The mixes with RCA replacement up to 50% and a cement content of 5% satisfy the strength and durability criteria recommended by IRC 37. A higher proportion of RCA was found to have a detrimental effect on mechanical properties and fatigue characteristics. It was found that the CSRCA mixes with 50% RCA replacement to NCA can be used as a base layer instead of a conventional cement-treated base (CTB) for flexible pavement. © 2023 Elsevier LtdItem Assessment of fly ash and ceramic powder incorporated concrete with steam-treated recycled concrete aggregates prioritising nano-silica(Springer Nature, 2024) Rao, A.U.; Shetty, P.P.; Bhandary, R.; Tantri, A.; S., S.; Yaragal, S.C.Present research involves determining the effects of a proposed novel nano-silica prioritized-steam-treated recycled concrete aggregate (RCA) on microstructural, mechanical, and durability aspects of concrete incorporated with waste ceramic powder (WCP). The study on novel nano-silica prioritized-steam-treated recycled concrete aggregate revealed that 3% nano-silica induction with 3-h steam treatment for 50% adhered mortar bonded RCA performed optimally. The physical characterization of treated RCA showed improvement compared to untreated RCA, which was confirmed by microstructure study indicating the formation of additional calcium silicate hydrates in the bonded adhered mortar of treated RCA. Furthermore, as WCP has significant contents of alumina and silica, an optimum ternary binder mix was developed with cement, fly ash, and WCP. Later, a study was performed to analyse the performance of treated RCA incorporated in WCP prioritized concrete mix. The mechanical performance of WCP prioritized concrete with treated RCA was investigated through compressive strength, flexural strength, split tensile strength, and modulus of elasticity. The quality was ensured through ultrasonic pulse velocity, water absorption, and density characterization. The durability of concrete was studied with 5% concentrated hydrochloric acid attack and sea water (pH = 8.3 to 8.7) exposure conditions for a duration of 148 days (including 28 days of portable water curing period). Overall, 30% of the ternary mixture based on WCP prioritization, 50% adhere mortar-based RCA, and 3% of nano-silica prioritization steam treatment (3 h) demonstrated the best performance in terms of both mechanical and durability aspects. The study concluded that due to its improved performance, the innovative nano-silica priority steam treatment approach could replace 100% of RCA in concrete. Furthermore, treated RCA being advantageous because of easy adoptable technique for real-time practices as well as maintaining consistency regards RCA characteristics throughout concrete mixture be the challenge. © The Author(s) 2024.Item Optimization and Characterization of Ferrochrome and Recycled Concrete Aggregate Mixes for Pavement Base Layers(American Society of Civil Engineers (ASCE), 2025) Chiranjeevi, K.; Kumar, D.H.; Yatish, R.G.; Mulangi, R.H.; Ravi Shankar, A.U.Utilizing alternate aggregates is crucial for conserving resources, promoting sustainability, and managing waste effectively. The focus of the current study was the utilization of ferrochrome aggregate (FCA) and recycled concrete aggregate (RCA) in cement-treated base layers with the objective of entirely replacing natural coarse aggregate (NCA). The study meticulously prepared cement treated recycled and ferrochrome aggregate (CTRFA) specimens with 3%, 5%, and 7% cement content. These specimens incorporated varying blends of RCA and FCA, ranging from 0% to 100%. Response surface method (RSM) was used to optimize the mixes by considering strength and durability criteria for cement treated bases (CTB). Microstructural characterization was aimed to explore aggregate surface roughness, mortar hardness, mineral phases, cracks, and elements within the matrix. The outcomes of optimization revealed that the optimal mixture, meeting the specifications of the Indian Road Congress, could be achieved by substituting 61% RCA and 39% FCA with 4.8% cement content. © 2024 American Society of Civil Engineers.