Browsing by Author "Hiremath, P.N."

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Eco-concrete for sustainability: utilizing aluminium dross and iron slag as partial replacement materials
(Springer Verlag, 2017) Javali, S.; Chandrashekar, A.R.; Naganna, S.R.; Manu, D.S.; Hiremath, P.N.; Preethi, H.G.; Vinod Kumar, N.
Emphasis on utilizing the industrial waste/discarded materials can be brought about by discovering innovative methods of disposal. One such a way of waste disposal can be through utilizing them in concrete production as a filler material or pozzolana. In this regard, the present study proposes to use the aluminium dross and granular iron slag as partial replacement materials for cement and natural sand, respectively, to develop eco-concrete. Nine mixes were produced with different proportions of cement, aluminium dross, sand and granular iron slag content. The aluminium dross was replaced at 5, 10, 15 and 20% of the weight of the cement. Initially, the optimal substitution percentage of aluminium dross was found without the substitution of iron slag based on the strength results. Later, by adopting the optimal aluminium dross percentage with cement, the granular iron slag was partially substituted at 10, 20, 30 and 40% of natural sand to find the overall optimal blend. The strength and durability properties of the M40 grade concrete employing these two admixture combinations were analysed. It was noticed that the strength and durability properties of the eco-concrete produced by incorporating aluminium dross ?5% and iron slag ?20% were comparable to that of conventional concrete. Furthermore, from the toxicity analysis, it was seen that the leaching of heavy and trace elements from the eco-concrete was negligibly small and within the limits. In near future, the cost-effective, eco-friendly materials and technologies can be opted as a perpetual strategy to overcome severe material shortages for resource conservation and economy. © 2017, Springer-Verlag GmbH Germany.
Effect of different curing regimes and durations on early strength development of reactive powder concrete
(2017) Hiremath, P.N.; Yaragal, S.C.
The early strength development of Reactive Powder Concrete (RPC) has been investigated under different curing regimes and compared with standard water curing condition. Four different curing regimes have been considered: ambient air curing, hot air curing, hot water bath curing and accelerated curing. The effect of hot air curing on strength development of RPC at different temperatures and durations are studied in detail. The present study is focused on the effect of combined curing regimes on the early strength development of RPC. Test results indicate that, among the four different curing regimes, hot water bath curing gives higher strength. The combined curing regime has considerably enhanced the compressive strength of RPC by about 63% as is evident by the rise in compressive strength from 110 MPa (standard curing) to 180 MPa (combined curing). Microstructure studies were also conducted to understand the arrangements of hydrated particles and development of other secondary hydrated products under different curing conditions using scanning electron microscope and X-ray diffraction spectroscopy respectively. 2017 Elsevier Ltd
Effect of different curing regimes and durations on early strength development of reactive powder concrete
(Elsevier Ltd, 2017) Hiremath, P.N.; Yaragal, S.C.
The early strength development of Reactive Powder Concrete (RPC) has been investigated under different curing regimes and compared with standard water curing condition. Four different curing regimes have been considered: ambient air curing, hot air curing, hot water bath curing and accelerated curing. The effect of hot air curing on strength development of RPC at different temperatures and durations are studied in detail. The present study is focused on the effect of combined curing regimes on the early strength development of RPC. Test results indicate that, among the four different curing regimes, hot water bath curing gives higher strength. The combined curing regime has considerably enhanced the compressive strength of RPC by about 63% as is evident by the rise in compressive strength from 110 MPa (standard curing) to 180 MPa (combined curing). Microstructure studies were also conducted to understand the arrangements of hydrated particles and development of other secondary hydrated products under different curing conditions using scanning electron microscope and X-ray diffraction spectroscopy respectively. © 2017 Elsevier Ltd
Experimental investigation on utilization of waste shredded rubber tire as a replacement to fine aggregate in concrete
(Springer, 2019) Hiremath, P.N.; Jayakesh, K.; Rai, R.; Naganna, N.S.; Yaragal, S.C.
Depletion of natural resources in the past few decades due to rapid construction activities all around the world has forced a threat to the availability of natural resources for future generation. The utilization of waste industrial by products, in the form of supplementary cementitious materials and waste tire rubber products replacing natural aggregates in production of concrete. In the present study performance of concrete mixes incorporating 2.5, 5, 7.5 and 10% Waste Shredded Rubber Tire (WSRT) as partial replacement of fine aggregate is investigated. Numerous research works have been conducted on replacement of aggregate by waste crumb rubber but data scarce on utilization of waste rubber in concrete directly. Hence to examine characteristics of shredded rubber tire based concretes, two sets of concrete specimen were produced. In the first set, shredded rubber tire is added directly without any pretreatment and in the second set the shredded rubber tire was immersed in NaOH solution for 24 h and then washed with water thoroughly and rubbed with sand paper to obtain the rough surface finish to facilitate improved bonding properties with cement matrix. To evaluate the performance of WSRT based concretes, fresh and hardened properties were determined by conducting slump tests on fresh mixes, and compression, flexural and impact tests on hardened concrete cubes and prisms. Proving results were obtained for potential use of WSRT in concretes for generalized applications. © Springer Nature Singapore Pte Ltd. 2019.
Influence of mixing method, speed and duration on the fresh and hardened properties of Reactive Powder Concrete
(2017) Hiremath, P.N.; Yaragal, S.C.
Production methodology of Reactive Powder Concrete (RPC) is not clearly established yet, as several parameters have a varied influence on the resulting fresh and hardened properties of RPC. Even for the same composition, the fresh and hardened properties differ significantly by changing mixing method, mixing speed and mixing time/duration. The present investigation is an attempt to study the effect of mixing method, speed and duration, on the fresh and hardened properties of RPC. The study also deals with the microstructure investigation of RPC mixes. Results indicate that improved mixing techniques prove beneficial in enhancing fresh and hardened properties of RPC. Mixing speed and duration also have significant effect on the fresh and hardened properties of RPC. Higher mixing speed and longer mixing duration decreases flow and strength characteristics of RPC. Microstructure analysis reveals that higher mixing speed and longer mixing duration increases percentage of pores in RPC, leading to reduced fresh and hardened properties. 2017 Elsevier Ltd
Influence of mixing method, speed and duration on the fresh and hardened properties of Reactive Powder Concrete
(Elsevier Ltd, 2017) Hiremath, P.N.; Yaragal, S.C.
Production methodology of Reactive Powder Concrete (RPC) is not clearly established yet, as several parameters have a varied influence on the resulting fresh and hardened properties of RPC. Even for the same composition, the fresh and hardened properties differ significantly by changing mixing method, mixing speed and mixing time/duration. The present investigation is an attempt to study the effect of mixing method, speed and duration, on the fresh and hardened properties of RPC. The study also deals with the microstructure investigation of RPC mixes. Results indicate that improved mixing techniques prove beneficial in enhancing fresh and hardened properties of RPC. Mixing speed and duration also have significant effect on the fresh and hardened properties of RPC. Higher mixing speed and longer mixing duration decreases flow and strength characteristics of RPC. Microstructure analysis reveals that higher mixing speed and longer mixing duration increases percentage of pores in RPC, leading to reduced fresh and hardened properties. © 2017 Elsevier Ltd
Investigation on Mechanical Properties of Reactive Powder Concrete under Different Curing Regimes
(Elsevier Ltd, 2017) Hiremath, P.N.; Yaragal, S.C.
Reactive Powder Concrete (RPC) is a form of Ultra High Performance Concrete (UHPC). The main constituents of RPC are cement, sand, silica fume, steel fiber and quartz powder with minimal water to binder ratio, without coarse aggregate. Due to its dense microstructure, RPC exhibit superior properties such as higher strength, durability and long term stability. Earlier researchers have produced RPC with Compressive strength up to 800 MPa and flexural strength of 75 MPa. In the present study, locally available materials are used to produce RPC of different mix proportions. The main objective is to study the effect of different curing regimes on the strength of RPC. The durability study is also carried out by way of accelerated corrosion test and acid test. Results have shown considerable enhancement in compressive strength when RPC specimen were subjected to hot air curing of different durations. RPC specimen cured under hot air curing and steam curing shown better performance compared to normal curing and air curing. Also RPC has shown better resistance to sulphate attack; further the rate of corrosion is low compared to high performance concrete. Â© 2017 Elsevier Ltd.
Performance evaluation of reactive powder concrete with polypropylene fibers at elevated temperatures
(2018) Hiremath, P.N.; Yaragal, S.C.
Reactive Powder Concrete (RPC) is a type of ultra-high strength concrete. Due to its dense microstructure, is vulnerable to explosive spalling at elevated temperatures. Remarkable application of RPC in special structures throughout the world has drawn the attention to understand the performance of RPC at elevated temperatures, which has not been investigated extensively yet. The main objective of this work was to evaluate the performance of RPC at elevated temperatures from 200 C to 800 C, by obtaining residual mechanical properties after exposure. The study aims to find an optimum fiber dosage for spalling protection of RPC. To improve the mechanical properties, RPC incorporating fiber dosage from 0.1% to 0.9% is studied. The thermal deterioration of RPC is assessed using ultrasonic pulse velocity, water absorption and sorptivity. Results shows that 0.1% fiber dosage is enough to control spalling of RPC up to 800 C. To enhance the residual properties of RPC exposed to elevated temperatures, it is recommended to use fiber dosage of 0.5%. The study also includes microstructural analysis of RPC subjected to elevated temperatures, to assess and evaluate the formation of pores and cracks. 2018 Elsevier Ltd
Performance evaluation of reactive powder concrete with polypropylene fibers at elevated temperatures
(Elsevier Ltd, 2018) Hiremath, P.N.; Yaragal, S.C.
Reactive Powder Concrete (RPC) is a type of ultra-high strength concrete. Due to its dense microstructure, is vulnerable to explosive spalling at elevated temperatures. Remarkable application of RPC in special structures throughout the world has drawn the attention to understand the performance of RPC at elevated temperatures, which has not been investigated extensively yet. The main objective of this work was to evaluate the performance of RPC at elevated temperatures from 200 °C to 800 °C, by obtaining residual mechanical properties after exposure. The study aims to find an optimum fiber dosage for spalling protection of RPC. To improve the mechanical properties, RPC incorporating fiber dosage from 0.1% to 0.9% is studied. The thermal deterioration of RPC is assessed using ultrasonic pulse velocity, water absorption and sorptivity. Results shows that 0.1% fiber dosage is enough to control spalling of RPC up to 800 °C. To enhance the residual properties of RPC exposed to elevated temperatures, it is recommended to use fiber dosage of 0.5%. The study also includes microstructural analysis of RPC subjected to elevated temperatures, to assess and evaluate the formation of pores and cracks. © 2018 Elsevier Ltd
Performance of Recycled Coarse Aggregate Concretes with Basalt Fibers at Elevated Temperatures
(Springer Science and Business Media Deutschland GmbH, 2022) Yaragal, S.C.; Hiremath, P.N.; Kalyan, M.M.; Kumar, D.; Shiji, P.P.
The utilization of Construction and Demolition waste (C&D) is gaining importance due to rapid depletion of natural aggregates, as well as due to increased awareness worldwide towards sustainable development. Water absorption characteristics of adhered mortar associated with C&D aggregates has to an extent hindered the potential of extensively using Recycled Coarse Aggregate (RCA) in concretes. The study examines the performance of concretes with replacement of natural coarse aggregates by RCA in different proportions. Attempts were made to enhance the compressive strength of RCA based concretes using basalt fibers. Results, show that possibility of using RCA based concretes (either 50 or 100% replacement) is possible without compromising strength, by incorporating 1.5% basalt fibers. Use of basalt fibers result in 13 and 19% enhanced strengths to concretes (for 50 and 100% replacement) apart from exhibiting superior elevated temperature endurance. Study also includes microstructural investigation of RCA based concretes with and without basalt fibers at elevated temperatures. Â© 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.