Conference Papers

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    Performance of concrete structures in the marine environment of Karnataka, India
    (2003) Devadas Bhat, S.; Samaga, B.R.
    Well-made concrete often survives better than might otherwise be expected, simply because of its impermeability and its ability to withstand the ingress of corrosive materials. The less the surplus voids the greater is the resistance to deterioration. Corrosion of steel is a multibillion-dollar problem worldwide. However, there are many structures, which show early deterioration, namely those exposed to aggressive environments. In the past and even at present times, too much emphasis is placed on concrete compressive strength rather than on environmental factors, which are known to affect concrete durability. This is one of the main reasons for serious deterioration of concrete structures that is prevalent today. The long-term behaviour of concrete structures has shown that their main cause of distress is reinforcement corrosion. One of the most aggressive exposure conditions for concrete is the marine environment In these condition chloride penetration and chloride induced reinforcement corrosion rates can be very high, often leading to a reduced service life. This paper describes a series of case studies of different types of concrete structures, subjected to marine environment in the West-Coast of Karnataka (INDIA), that have suffered extensive deterioration due to corrosion.
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    Performance Evaluation of Fly-ash based Self-compacting geopolymer concrete mixes
    (Institute of Physics Publishing helen.craven@iop.org, 2019) Manjunath, R.; Ranganath, R.V.
    In this paper, an attempt has been made to develop Fly ash based self- compacting geopolymer concrete mixes with varying volume of pastes using conventionally available river sand as fine aggregate and crushed granite chips as coarse aggregate. These mixes were developed usingFly ash as the only major source material in the production of SCC mixes. Different amounts of Sodium silicate solutions, with specified amounts of Sodium Hydroxide flakes dissolved in them, are used as alkaline solutions. The total of four mixes were developed with varying volume of pastes in the range of 0.40 - 0.52 (within an interval of 0.04). These mixes were evaluated for their flow ability characteristics as per the relevant EFNARC guidelines. Further the mixes were evaluated for their mechanical properties in terms of compressive strength, splitting tensile strength and water absorption characteristics. Durability tests by means of subjecting to acidic and sulphate environments, along with their resistances to sustained elevated temperatures for a sustained period of 2 hours upto 800° C were carried out for all these mixes. The test results indicate better flow ability characteristics, along with their mechanical and durability properties. © 2019 IOP Publishing Ltd. All rights reserved.
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    Experimental Studies on Lateritic Soil Stabilized with Cement, Coir and Aggregate
    (Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2021) Ravi Shankar, A.U.R.; Priyanka, B.A.; Avinash
    The characteristics of subgrade soil play a vital role in designing the pavement structure so that the pavement has required support from the bottom layer. During adverse weather conditions and higher traffic loads moving on any pavement, it should be able to withstand the impact and perform well for longer duration. Load is transmitted from pavement to the subgrade layer and distributed evenly through the soil particles. All types of soil are not capable of handling such impacts by their own and needs additional stabilization processes. Several stabilization processes are available in which the best one has to be taken into consideration. Fibers such as coconut coir are important in giving extra stability to the soil particles. Cement is well-known material in construction sector along with aggregates. Lateritic soil is available abundantly in coastal areas of southern parts of India which has porous structure and demands stabilization when the intended purpose is specific and requires higher strength and durability. In this study, coconut coir along with cement and aggregate are taken as stabilization materials to stabilize lateritic soil. Initially, basic properties of soil like plastic limit, liquid limit and plasticity index are determined. Grain size analysis is done and modified Proctor test is conducted to determine the optimum moisture content (OMC) and maximum dry density (MDD) of the soil. Unconfined compression test (UCS), California bearing ratio test (CBR), flexural fatigue analysis, durability properties with respect to wet-dry cycles and freeze–thaw cycles are evaluated for untreated and treated soil specimen. As per UCS values, cement can be taken at an optimum dosage of 6%. The coir fibers from natural husk of coconut and aggregates of 10 mm below size were added to the soil–cement mixes and an optimum dosage of coir and aggregate is determined. The study showed positive results in terms of CBR values of cement-aggregate treated soil. © 2021, Springer Nature Singapore Pte Ltd.
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    Predicting the Service Life of Reinforced Concrete by Incorporating the Experimentally Determined Properties of Steel–Concrete Interface and Corrosion
    (Springer Science and Business Media Deutschland GmbH, 2021) Sumukh, E.P.; Goudar, S.K.; Das, B.B.
    Service life of a reinforced concrete structure depends on its durability in aggressive exposure conditions. In the case of reinforced concrete structures, the phenomenon that directly affects its durability is corrosion of rebar, which has direct influence on the residual service life. Corrosion in reinforced concrete basically initiates at its weakest zone called steel–concrete interface due to its porous nature. The extent of this porous zone is being represented in terms of Porous zone thickness which has been extensively reported by various researchers. This porous zone thickness is one of the key influencing factors in the prediction of residual service life of the reinforced concrete structure. Several mathematical models were proposed by various researchers to estimate the time required for cover cracking of concrete due to rebar corrosion by assuming different values of porous zone thickness (PZT) without any systematic experimental investigation. Assuming a steady value of PZT for all kinds of concrete without any practical justification will misinterpret the predicted residual service life. In the present work, an effort has been made to evaluate an existing analytical model to predict the time to concrete cover cracking by incorporating the experimentally obtained and published data on porous zone thickness. It was found that the porous zone thickness and rate of corrosion have a major role in evaluating the residual service life of reinforced concrete structures. © 2021, Springer Nature Singapore Pte Ltd.
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    Influence of Incorporating Phase Change Materials on Cementitious System—A Review
    (Springer Science and Business Media Deutschland GmbH, 2021) Snehal, K.; Das, B.B.
    Phase change materials (PCMs) are gaining more attention in achieving the sustainability and are being widely adopted as a green building material because of their exclusive ability to store latent heat of thermal energy. PCMs have a capacity to minimize the energy loads and to provide thermal comforts in building infrastructures by its iterative cycle of absorbing and releasing the heat energy. The potential need for manipulating the heating and cooling effect in buildings is significantly increasing especially in temperature fluctuating and varied climatic regions. It is for this one of the significant reasons, PCMs are getting pronounced interest by the research fraternity in the development of a thermally effective PCM-based construction material. In this paper, attempts were made to compile the data reported by the previous researchers on the influence of incorporating PCMs in the engineering properties of cementitious system such as slump, compressive strength, flexural strength, density, porosity, water absorption, shrinkage, durability, heat of hydration, specific heat capacity and thermal conductivity. This paper also discusses the most favorable content of PCM addition and effective methods of incorporating PCMs in the cementitious system. © 2021, Springer Nature Singapore Pte Ltd.
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    Impact of Phase Change Materials on the Durability Properties of Cementitious Composites—A Review
    (Springer Science and Business Media Deutschland GmbH, 2023) Vismaya, K.; Snehal, K.; Das, B.B.
    Phase change materials (PCMs) are the novel thermal storage materials which have an ability to engross and dispel heat during the process of phase transition from solid to liquid and vice versa. Utilization of PCMs in cementitious composites has gained a lot of attention from the research fraternity to minimize the energy loadings used for space conditioning and heating in building. Impact of PCM’s presence in cementitious composites on the durability parameters is the need for its better usage. This paper gives the state of review on the influence of inclusion of phase change materials in the cementitious system on its various durability aspects. Durability properties such as porosity, water absorption, shrinkage, chloride ingression, and chemical attacks are compiled in this article. It is stated that the integration of PCM in cement composites enhances the porosity of cementitious system. Major hindrance described by the researchers is the interruption of hydration activity of cementitious system by the addition of PCM. Literature also signified that the micro/nano encapsulates PCMs and the use of highly reactive Pozzolans such as silica fume or nano-silica in conjunction with PCMs has the ability to lock up the limitations of PCMs. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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    Laboratory Investigation of Lateritic Soil Stabilized with Arecanut Coir Along with Cement and Its Suitability as a Modified Subgrade
    (Springer Science and Business Media Deutschland GmbH, 2023) Chethan, B.A.; Lekha, B.M.; Ravi Shankar, A.U.
    If a pavement is constructed on weak soil, its lifespan drastically reduces due to the low strength induced by moisture-induced destresses. Such soils may undergo considerable changes in volume. In order to modify these properties, soil stabilization can be done. By stabilizing the soil along with the improvement in strength, its durability can be increased. Stabilization may be of chemical or mechanical type. In this investigation, lateritic soil was stabilized using 0.2–1% arecanut coir, and its compaction characteristics were evaluated. The lateritic soil is found to be nondurable. The reinforcement alone could not improve the strength and durability effectively. Therefore, 3% binding agent ordinary Portland cement (43 grade) was added to the mix. Due to cement stabilization, UCS and CBR values were improved, and the optimum values were observed at 0.6% arecanut coir dosage. The addition of cement has resulted in a change in silica, alumina, and calcium oxide contents, thereby contributing to the formation of hydration products. The samples with 1% coir and cement have completed 12 wet–dry cycles, but the weight loss observed was >14%. All the specimens showed low soil loss under freeze–thaw cycles. The performance of cured specimens under fatigue loading was satisfactory. Since the specimens could not pass wet–dry durability criteria, they can be considered for modified subgrade. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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    Alkali Activated Black Cotton Soil with Partial Replacement of Class F Fly Ash and Areca Nut Fiber Reinforcement
    (Springer Science and Business Media Deutschland GmbH, 2023) Chethan, B.A.; Ravi Shankar, A.U.; Chinnabhandar, R.K.; Kumar, D.H.
    Alkali activation has received great attention for improving the soil properties with suitable precursor materials. Industrial byproduct class F fly ash was suitably utilized to improve Black Cotton (BC) soil properties along with ordinary Portland cement by various researchers. However, the CO2 emission associated with cement production has enforced the evaluation of alternative binders. Laboratory investigations were conducted on BC soil by admixing various fly ash dosages (0–50%) and reinforcing the mix with 0.5% areca nut fiber. Alkali activator solution prepared using 8 molar sodium hydroxide solution (SH) and sodium silicate solution (SS) at 1.5 SS/SH ratio showed significant improvement in Unconfined Compressive Strength (UCS) of stabilized BC soil on 7 and 28 days curing. The reinforcement was effective in improving the flexural strength of stabilized mixes. Exorbitant unsoaked California Bearing Ratio (CBR) values were observed on 28 days of curing. However, the samples could retain low soaked CBR values despite reinforcement. Scanning Electron Microscope (SEM) images showed the reduction of shrinkage cracks and strong bonding of fibers in the stabilized mix. X-Ray Diffraction (XRD) patterns evidenced the formation of various hydration products due to the alkali reaction, which resulted in the high strength gain of mixes at ambient temperature curing. The leaching of mineral constituents from the set mix lead to the failure of durability samples. Due to nondurability, the alkali activation with a selected precursor cannot suit pavement materials requirements. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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    Recent Advances in Structural Engineering—An Introduction
    (Springer Science and Business Media Deutschland GmbH, 2024) Sreekeshava, K.S.; Kolathayar, S.; Vinod Chandra Menon, N.; Bhargavi, C.
    This comprehensive overview explores recent advances in structural engineering with a focus on sustainability, resilience and performance evaluation of structural members. In the contemporary construction landscape, where environmental concerns and resource limitations significantly influence design practices, the integration of sustainability principles into structural engineering has become imperative. The introductory section emphasizes the multifaceted nature of structural engineering, highlighting the critical elements contributing to sustainable and resilient designs. The analysis of design aspects is crucial, considering strength criteria, energy efficiency, occupant comfort, and minimal environmental impact. Modern structural engineers employ a diverse range of tools and techniques to create environmentally responsible designs, addressing challenges posed by evolving expectations and resource constraints. The strength criteria of structural members, such as ultimate capacity, energy absorption, axial stiffness and durability, are explored through experimental investigations on innovative materials. Studies include the combined use of metakaolin and ground granulated blast-furnace slag in concrete for marine environments, the comparison of alkali-activated concrete with conventional mortar against sulfuric acid attack and the utilization of coconut coir fibre in limestone calcined clay cement concrete. Advancements in reinforcing techniques, including glass fibre-reinforced polymers, carbon fibres and bamboo as alternative construction materials, contribute to the pursuit of sustainable building practices. The exploration extends to seismic performance, wind load analysis and the use of base isolation systems to enhance the resilience of structures. Performance evaluation of structural members encompasses diverse studies, including the behaviour of cold-formed steel tubular columns, stainless steel-reinforced concrete and the seismic response of buildings in different terrain categories. The impact of external factors such as wind, fire and temperature on structural elements is also discussed. Analysis and design aspects cover a range of topics, from the use of finite element modelling to evaluate the behaviour of hybrid composite laminates to the seismic analysis of reinforced concrete frames. The volume emphasizes the importance of progressive collapse analysis, base isolation systems and the evaluation of masonry wall safety. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
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    Recent Advances in Building Materials and Technologies–An Introduction
    (Springer Science and Business Media Deutschland GmbH, 2024) Kolathayar, S.; Sreekeshava, K.S.; Vinod Chandra Menon, N.; Shekhawat, P.; Bhargavi, C.
    This volume underscores the critical influence of building materials on construction projects, emphasizing their role in progress, quality, and operational durability. The construction industry's explosive growth, aligning with economic development, is noted as a positive force for industrialization and modernization. Amidst climate change considerations, the imperative for sustainable and resilient building materials is highlighted. Alternative materials, whether fully or partially replacing aggregates or cement, emerge as vital for sustainable and resilient construction. These include diverse industrial wastes (e.g., plastics, construction by-products) and fibers/ashes (e.g., jute, steel, sugarcane bagasse). A notable innovation is the geopolymer, an alkali-activated binder offering superior durability and mechanical strength with lower energy consumption and CO2 emissions than traditional cement. In waste material utilization, studies explore plastic, waste tea, scrap ceramic tiles, and construction waste in concrete, addressing both sustainable waste management and high-performance structures. Ash applications consider wood ash, palm oil fuel ash, and agricultural waste ashes as sustainable alternatives to traditional cement. Geopolymer advancements encompass mechanical behavior, heat conditions, and novel applications like using iron ore tailings. Durability assessment explores nanotechnology to enhance concrete properties and reduce energy consumption. Fiber-reinforced materials and compressed stabilized earth blocks reinforced with coconut fiber aim for enhanced mechanical properties and reduced carbon emissions. The volume also touches on construction project investigations, addressing safety, progress tracking, and construction delay analysis techniques. In essence, this synthesis offers a panoramic view of recent advances in building materials and technologies, contributing to a holistic understanding of sustainable and resilient construction practices. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.