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Item Influence of sample preparation techniques on microstructure and nano-mechanical properties of steel-concrete interface(2020) Goudar S.K.; Das B.B.; Arya S.B.; Shivaprasad K.N.Interface between steel and concrete is characterized as highly porous and weakest region which influences both mechanical properties and durability of a reinforced concrete structure. The properties of the steel-concrete interface (SCI), especially the porous zone thickness are prime factors in predicting the time for corrosion initiation to corrosion cracking in service life prediction models. Measurement of porous zone thickness of reinforced concrete samples is sensitive to the sample preparation technique for microscopic observations. It is observed that there are hardly any research articles are available in the literature regarding the sample preparation technique of reinforced concrete sample for SCI analysis. In the present study, a detailed and stepwise sample preparation technique is proposed where there is minimal damage found to be observed to SCI. The major focus is on the speed of cutting tool that is being used for obtaining a relatively small size of sample from the bulk reinforced concrete member. The properties such as porous zone thickness and nano mechanical properties around the SCI were determined through scanning electron microscopy and nano-indentation, respectively. A significant variation in porous zone thickness around SCI was observed and measured value of average porous zone thickness is found to be approximately 1.8 times higher from high-speed cutting to low-speed. A similar kind of observation was noticed for nano mechanical properties. In addition to speed of cutting, there found to be other factors such as pressing force for specimen, duration of polishing and heating temperature has significant influence on interfacial properties. © 2020 Elsevier LtdItem Influence of Integration of Phase Change Materials on Hydration and Microstructure Properties of Nanosilica Admixed Cementitious Mortar(2020) Snehal K.; Das B.B.; Kumar S.The present study demonstrates the influence of integrating phase change materials (PCMs) on hydration and microstructure properties of nanosilica admixed cementitious mortar. First, the optimized dosage of nanosilica in correspondence to compressive strength was determined. Subsequently, the desired proportion of PCMs was identified pertaining to a designated compressive strength of 35 MPa at the curing age of 28 days. The hydration and microstructure studies were carried out through thermo gravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM), respectively. Further, thermal properties were determined by means of differential scanning calorimetry (DSC). Incorporation of nanosilica into the cementitious mortar was found to have a positive influence on early strength development and durability, however, there was found to be an increase in chemical shrinkage as compared to the control mixture. PCMs integrated cementitious mortar improved the thermal efficiency as well as reduced the chemical shrinkage, but adversely affected the mechanical, hydration, and durability properties. With respect to development of compressive strength of the cementitious mortar, it is found that n-octadecane PCMs performed better amidst other PCMs, such as paraffin and sodium carbonate hydrates. Further, studies were carried out on cementitious mortar having both nanosilica (optimized proportion) and PCMs (the best performing). From the results, it is found that cementitious mortar comprising of both nanosilica and PCMs have compensated the drawbacks of one another. Blended mortar (having both nanosilica and PCMs) showed superior strength gain at early age, better durability resistance, low chemical shrinkage, and superior thermal performance. © 2020 American Society of Civil Engineers.Item Automation of Curing Using Prefabricated Sensors(2021) Agarwalla A.; Das B.B.Curing is one of the universal phenomena followed after casting and finishing of concrete over an extended period of time, which helps to develop the compressive strength and durability by maintaining an optimum moisture and temperature condition. It keeps the concrete hydrated, restricts volumetric shrinkage, provides resistance to abrasion, freezing and thawing. There are many ways to cure concrete but, in this article, discussion will be on automation of curing using IoT and moisture sensors and relays which will likely replicate the lab condition on site by maintaining constant moisture content in concrete by supplying required amount of water. Generally, on site the curing process is carried out for 6–7 days once or twice a day at a large interval as a result of which the free moisture content falls and the rate of hydration decreases. It results in poor compressive strength and durability compared with laboratory samples because the 7 days compressive strength is not achieved which is more important than that of 28 days compressive strength which is successfully achieved in the lab. Various technologies used in this article will help in real-time monitoring of concrete condition with ease which will further be beneficial for the construction industry. This paper will cover how these technologies are integrated to automate the whole process, and its effect on compressive strength of concrete for which a consistent mix of M20, M25, M30 was prepared to compare the result of strength of concrete at 3, 7 and 28 days of curing in three different conditions, giving the strength of in-situ automatically cured concrete sample similar to that of laboratory cured concrete sample and an increase in 16.09% of compressive strength was observed with respect to concrete cured manually in site conditions. © 2021, Springer Nature Singapore Pte Ltd.Item Safety Stock in Inventory Management and Wastage Analysis at Construction Sites(2021) Paul B.; Tondihal S.; Das B.B.Inventory control in construction projects is a key function to the project success. Inventory serves as a link between planning and execution of a project. In construction industry, majority of the cost is involved in inventories so it is important to keep the inventories under strict control otherwise it may lead to cost and time overrun. As construction industry consumes large part of inventories, so it produces huge amount of wastes. It is established that the wastages have a significant negative impact on cost and time of a project. So, it is of utmost importance to know the impact of these causes of wastages on cost and time so that a proper mitigation plan can be prepared and impact of these causes of wastage be reduced or eliminated. This paper mainly put emphasis on safety stock analysis aiming to determine the safety stock of inventories after calculation of average lead time, actual lead time, average demand per day, standard deviation and service factor from the set of data obtained from the site. It also aims to provide a model for automation of safety stocks to prevent stock-outs using PYTHON software. Apart from that, it involves a questionnaire survey to analyze the impact of various causes of wastage in construction on the basis of cost and time. © 2021, Springer Nature Singapore Pte Ltd.Item Resource Buffers in Construction Projects(2021) Hegde A.L.; Jain A.; Das B.B.Critical Chain Project Management (CCPM) is created on techniques and procedures taken from the Theory of Constraints (TOC). CCPM was presented in late 90s (1997) in a book named Critical Chain from several studies by Standish Group and others for customary project management methods, only half of the projects normally finish on time, projects generally take twice the duration originally planned, twice of the original planned cost, around 70% of projects fall short of their planned scope, and round about 30% of the projects are shut down in midway. CCPM can be used to avoid these customary statistics. Usually, CCPM case studies report greater than 95% on-time and on-budget completion when CCPM is applied in the approved manner. Initially, the CCPM guidelines and prescriptions and discovers its differences with customary project scheduling methods like Program Evaluation and Review Technique (PERT) and Critical Path Method (CPM). Then the Critical Chain Project Management solution has been outlined, which covers all the proposed steps—the elements of the Critical Chain Project Management solution. Thereafter, the methodology used for data collection and analysis has been explained. Further, it explains the application of CCPM in a Transmission Line Project undertaken by Larsen and Toubro Power Transmission and Distribution. Further, the results of the analysis and discussions about the same have been written. © 2021, Springer Nature Singapore Pte Ltd.Item Pre-Engineered Building Design of Gas-Insulated Substation Housed Under Pressurized Ventilation(2021) Roopesh N.; Swamy K.A.; Das B.B.Building construction in India is carried out using conventional materials like concrete but it has limitation of span and size of components. As a result, large span areas that are essentially required for housing Electrical Extra High Voltage Gas Insulated Switchgears could not be covered by simple frames and required complex frame arrangements thereby increasing the required completion time. For design, steel has been the preferred material because of its ductile, strength, flexible, recyclability nature and low cost. With technology transfers, entrepreneurs had established steel centres where entire design to production is carried under one roof and the product is erected at site. These factories had given advantage of fabricating components either ahead or parallel to the civil works at site, thus saving time. Introducing the concept of Pre-Engineered building (PEB) into structural design resulted in design optimization and many advantages, including economy and easier fabrication when compared with the Conventional Steel building (CSB). PEB construction is widely gaining popularity over regular conventional buildings in India due to its sheer advantage in time saving. However, there is a challenge of proper and optimized design suiting to the Electrical Substation requirements such as pressurized atmospheric environment, Maintenance walkways, entry of electrical Bus ducts at various levels and locations. Any overlooking of the above may lead to overall failure of the electrical system. This would make it unique from the normal conventional PEB buildings done for Ware houses, Factories, etc. © 2021, Springer Nature Singapore Pte Ltd.Item Productivity Analysis of Shuttering Works for Sewage Treatment Plant(2021) Pandey A.; Chaudhary P.K.; Das B.B.Formwork is considered as important element of construction projects like in traditional reinforced concrete infrastructure projects. It is labor-intensive work that requires highly skilled workers such as carpenters, bar benders, etc., to execute the work more accurately and efficiently. In view of the fact that it is difficult to find high-skilled workers for formwork process and hence it is important to find the ways or methods of formwork construction that is less labor dependent or in other words methods that are highly productive with minimum number of workers. The quality of formwork exerts a direct influence on the surface of concrete and on its dimensions. Since reinforced concrete work is involved in majority of the buildings, the level of workmanship of the construction project can be identified by seeing the quality of formwork. In order to improve the productivity of the formwork process and its quality then it is necessary to improve its working methodology by identifying the bottlenecks using scientific management. And as we very well know that money is always the center of discussion in our construction projects. To complete the project within its expected, designed cost of the project is one of the major requirements of the project to become a successful project. That’s why the topic ‘Productivity analysis in shuttering for Sewer Treatment Plant Project’ is a great tool to analyze the shortcomings in the present methodology of formwork erection and to mechanize a highly effective model for formwork and this can be achieved by the productivity analysis. © 2021, Springer Nature Singapore Pte Ltd.Item Production of Artificial Aggregates Using Industrial By-Products Admixed with Mine Tailings—A Sustainable Solution(2021) Sharath B.P.; Das B.B.This experimental cum research exploration is focused on the production of artificial aggregates with an adoption of pelletization technique. The influential factors for ascertaining the efficiency of the production process are nature of binding agent, required moisture content, process duration and dosage of alkali binder. Aggregates were produced in various combinations including the industrial by-products replaced partially by mine tailings with the addition of some percentages of lime. These produced aggregates were analysed for their engineering properties. It was observed that with the utilization of these mine tailings in this production of artificial aggregates have given an enhancement in the basic characteristic properties of the produced aggregates which are nearly comparable to that of natural aggregates. © 2021, Springer Nature Singapore Pte Ltd.Item Predicting the Service Life of Reinforced Concrete by Incorporating the Experimentally Determined Properties of Steel–Concrete Interface and Corrosion(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.Item A Review on the Properties of Steel-Concrete Interface and Characterization Methods(2021) Sumukh E.P.; Goudar S.K.; Das B.B.The Steel-Concrete interface (SCI) is usually regarded as the weakest region, which influences both mechanical properties and durability of reinforced concrete structures. Several researchers have well explored and defined the importance of SCI on the service life of the reinforced concrete structures as it directly affects the durability. The primary objective of this paper is to report and compare a variety of published findings and microstructural analysis on the SCI in one place which appears in reinforced concrete. The information available on the occurrence, formation, properties, various characterizing and analysing techniques of SCI are reviewed for a better understanding of microstructural properties of SCI on the hardened and durability properties of reinforced concrete. It was found that the SCI exhibits significant spatial inhomogeneity along and around as well as perpendicular to the reinforcing steel. Significant factors like quantification of porosity, porous zone thickness and actions that affect the properties of SCI like wall effect, bleeding, settlement and segregation of fresh concrete which were favourable to both initiation and propagation of corrosion are described in this paper. The influence of w/c ratio, hydration age, steel orientation and mineral admixtures on the distribution profiles of hydration products and Engineering properties of SCI is also discussed. © 2021, Springer Nature Singapore Pte Ltd.