3. Book Chapters
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Item Characterization of Mechanical and Microstructural Properties of FA and GGBS-Based Geopolymer Mortar Cured in Ambient Condition(2021) Prasanna K.M.; Tamboli S.; Das B.B.Fly ash-based geopolymer mortars require heat curing to achieve its properties, which limits its practical application at ambient conditions. The present study was aimed to accomplish the need for application of fly ash-based geopolymers for practical viability without any heat curing by inclusion of ground-granulated blast furnace slag (GGBS). The results revealed that inclusion of GGBS as a partial replacement to fly ash (FA) in geopolymer mortar, which is cured in ambient curing condition, can be able to achieve required setting time and compressive strength. Amalgamation of GGBS with class FA as binder in geopolymerization lend a hand to attain compressive strength as well as setting time which is analogous to ordinary Portland cement (OPC). Microstructural properties were studied using scanning electron microscopy. © 2021, Springer Nature Singapore Pte Ltd.Item Application of Andreassen and Modified Andreassen Model on Cementitious Mixture Design: A Review(2021) Snehal K.; Das B.B.Cement is a widely used construction material and its consumption on large-scale causes environmental degradation; thus, more emphasis is being given on industrial by-products as alternative materials to cement for their sustainable usage. It is necessary that varying particle size of supplementary cementitious particles is to be used for filling the voids to form a dense particle-packed concrete. The selection of right combination of material is tedious job by trials involving different replacement materials and the resultant concrete may show unexpected results; thus, a more suitable method is the selection of materials based on optimum packing of particles. To select the optimum size of replacement materials particle packing models are essential, so that a low-cement concrete can be prepared which will be ecological as well as economical with improved density, low porosity and high compressive strength. It is found that there are different models have been developed to achieve optimal packing. However, application of Andreassen and modified Andreassen models for the particle packing of multiple ingredients of cementitious matrix found to be largely being accepted by the researchers. This paper reviews the application of Andreassen and modified Andreassen models for the effective particle packing investigations on cementitious particles. It also reviews the software’s employed for designing various cementitious mixtures based on Andreassen and modified Andreassen models. © 2021, Springer Nature Singapore Pte Ltd.Item A Review on Mechanical and Microstructure Properties of Reinforced Concrete Exposed to High Temperatures(2021) Goudar S.K.; Gedela S.K.; Das B.B.This paper presents the recent research progress on the response of concrete exposed to fire or high temperatures. The main highlight of this review paper is a compilation of previously reported data regarding the variations in mechanical properties and microstructure properties of concrete when exposed to high temperatures. The concrete structures get deteriorated at the macro- and microscopic levels due to high-temperature exposure. The macro-level damages can be measured with degradation in mechanical properties such as the reduction in compressive strength, weight loss, changes in elastic properties, reduction of bond strength in reinforced concrete, etc. The macro-cracks on the surface of concrete causes spalling which can be observed after exposing the concrete samples to more than 300 ℃. The compressive strength of the concrete reduces slightly till 400 ℃, and when the temperature increased to 600 ℃, there was an exponential reduction in the compressive strength of concrete. Another important parameter is bond strength degradation, which plays a crucial role in durability issues. To understand the deterioration phenomenon and changes in mechanical properties, the changes at the level of the microstructure of concrete need to be understood. Dehydration of products causes deterioration of mechanical properties and weight loss of concrete when exposed to high temperatures. At different temperatures, the microstructure changes and the response of hydration products such as calcium hydroxide (CH), CSH gel, unhydrated cement and capillary water reported by previous researchers are compiled and discussed. © 2021, Springer Nature Singapore Pte Ltd.Item Fast Setting Steel Fibre Geopolymer Mortar Cured Under Ambient Temperature(2021) Prasanna K.M.; Theodose I.; Shivaprasad K.N.; Das B.B.Cement and cementitious materials are being used worldwide as the most popular multipurpose construction materials but the greenhouse gas such as carbon dioxide (CO2) produced during its manufacturing process creating a huge environmental hazard, thus efforts have been made for alternative binders. Geopolymer binder is new age binder alternative to ordinary Portland cement in infrastructure projects because it is produced from eco-friendly and industrial waste materials. This study was aimed to produce fast setting with ground-granulated blast-furnace slag (GGBS) in fly ash-based geopolymer mortar incorporated with steel fibres cured under ambient temperature. In this research, alkaline to binder ratio was varied from 0.5 to 0.8, crimped steel fibre are varied from 0.5 to 1.5% by total volume of binder and combination of fly ash (FA) and GGBS (100%:0%, 90%:10%, 80%:20%, 70%:30%, 60%:40% and 50%:50%) as binder were used for preparation of fibre geopolymer mortar. The tests conducted include stetting time and flowability of geopolymer mortar, compressive strength and microstructural characterisation of steel fibre geopolymer mortar. The tests for compressive strength were carried out on standard size of mortar samples at curing period of 3, 7 and 28 days. It is noted from the test results that increase in GGBS content setting times were decreased; however, the compressive strength of fly ash-based geopolymer mortar increased. The highest compressive strength at 28 days of curing period was found to be 69.5 MPa, which is obtained with content of 1% of steel fibres and alkaline to binder ratio of 0.6 with 50%:50% binder’s proportions. Further, it is observed that the incorporation of steel fibres in plain geopolymer mortar have enhanced the compressive strength and optimum dosage of fibres was found to be 1%. © 2021, Springer Nature Singapore Pte Ltd.Item Optimization of resources by real-time correlation study for maximizing the productivity(2019) Agrawal A.; Das B.B.; Malik S.K.Time and cost are two of the most important factors to consider in each construction project. In order to maximize performance, both the client and the contractor will work to optimize both the duration of the project and its cost. The fundamental beginning is to support the same production for the different equipment to achieve the maximum efficiency in each period of time. With the limited availability of resources, the work must be continuous and the period of time between operations and final must be kept. This paper aims to minimize the project total time and cost by means of the assignment of equipment of work to the different production lines of the activities. Construction project refers to a high-stake endeavor aiming at time-bound predetermined performance objective. Matching resources are planned and procured so that all activities can be executed according to a prefixed time schedule. Result shows that the optimization of resources is highly dependent on proper planning mechanism and efficient monitoring of its execution. © Springer Nature Singapore Pte Ltd. 2019.Item Methods to monitor resources and logistic planning at project sites(2019) Challa P.R.; Das B.B.Construction projects are unique and complex in nature. Various resources such as men, material, plant and machinery, capital, information, space, time, and above all local infrastructure are involved in the construction activity. Hence, controlling and monitoring the flow of resources plays a vital role in the timely completion of the project contributing to reduced delays leading to time and cost optimization. Productivity analysis of transit mixer, workmen have been done through data collected from a commercial project and suggestions to improve the same have been proposed. Logistics of two different sites one with onsite storage and other with offsite storage have been studied and recommendations to improve the logistics are provided. Some of the methods to monitor the resources on site have been proposed, which can be used without any hindrances at the construction project sites. Further, based on planned resources, a simplified logistics planning template and labour productivity monitoring data sheet which can be updated based on project’s progress is developed that can be used with ease at project site considering all the necessary factors. © Springer Nature Singapore Pte Ltd. 2019.Item Mechanical properties of fiber-reinforced concrete using coal-bottom ash as replacement of fine aggregate(2019) Goudar S.K.; Shivaprasad K.N.; Das B.B.The present investigation aims to study the significance of coal coal-bottom ash as a partial replacement to natural river sand in fiber-reinforced concrete (FRC). Hooked-end steel fibers were used to produce fiber-reinforced concrete at a fiber content of 1.5% by volume concrete. About 30% of natural sand was replaced with coal coal-bottom ash to produce M30 grade concrete with a water–cement ratio of 0.45. The prolonged curing period has a positive effect on the coal, coal-bottom ash replaced concretes. There was a slight increment in the compressive strength of FRC because of inclusion of steel fibers. However, significant improvements were observed in flexural and split tensile strength of FRC due to the inclusion of steel fibers. The optimum content of coal, coal-bottom ash replacement to natural sand was found to be 20%. © Springer Nature Singapore Pte Ltd. 2019.Item Mineralogical study of concretes prepared using carbonated flyash as part replacement of cement(2019) Sahoo S.; Das B.B.Cement production is excessive energy intensive, responsible for depletion of natural layers and high carbon foot print. Thus search for an environmentally benign cement substitute still is an on-going process. Fly ash is a well-established concrete admixture enhancing the strength, durability and micro-structural properties. As well as it is a good reagent to sequester atmospheric carbon dioxide. Concretes prepared through part replacement of cement by carbonated fly ash demonstrate good resistance against chloride, acid and sulfate attack. In the present research mineralogical study of CFC (Carbonated Fly ash concrete) has been conducted through XRD analysis. XRD of control concrete (CC) and fly ash concrete (FC) have also been carried out to study the comparative distributions of mineral crystallites present in concretes. The tests have been conducted in the concrete specimens cured in water for 28 days and 90 days to study the effect of hydration and extent of pozzolanic reaction on the mineralogical composition. Two replacement levels of 25 and 40% were considered for experimentation. The qualitative XRD investigation yielded a higher intensity of CaCO3 in the concretes prepared using Carbonated Fly ash. The presence of CaCO3 helped the concretes in developed chemical resistances dense and improved microstructure. The thermogravimetric analysis further confirmed the presence of higher Carbonates in the CFC specimens. © Springer Nature Singapore Pte Ltd. 2019.Item Implication of concrete with chemical admixture cured in low temperature on strength, chloride permeability and microstructure(2019) Ghosh A.H.; Das B.B.Concrete does not gain complete strength when cured in low temperature as the hydration of cement does not take place completely. The concrete cured in cold weather does not gain early strength and leads to improper setting and uneven strength gain due to the freezing of the water mixed with the cement. Hence, there are many strength-related problems faced at site due to cold weather particularly in parts of north India where the temperature reaches below freezing point of water during the winter season. The study focused on the effect of combination of accelerator, superplasticizer and air-entraining admixture on microstructure, compressive strength and chloride ion penetration of concrete cured at +5 °C and a comparative study with normal cured concrete with chemical admixture. Five different mixes were used containing varying amount of accelerators, superplasticizers and air-entraining admixture of a manufacturer which are available for use in India. The results for compression strength show that the concrete mix with higher dosage of accelerator had higher strength. The strength results were nearly the value of normal cured concrete with chemical admixture. Rapid chloride permeability test showed very low permeability for all of specimens of last mix, and results were nearly comparable to normal cured concrete. The microstructure study of concrete with admixture ensures a dense structure formation resulting in higher strength at low temperature. © Springer Nature Singapore Pte Ltd. 2019.Item Durability studies of steel fibre reinforced concrete(2019) Yadav S.; Das B.B.; Goudar S.K.In the present investigation, the effect of different dosage of steel fibres on bond strength between steel and concrete in reinforced concrete was investigated. As a part of durability study, the combined effect of marine environment and varying levels of pH on the ultimate bond strength retention and compressive strength retention of steel fibre reinforced concrete was also investigated. Durability studies were carried out by exposing the 28 days cured cubical specimens into marine environment having different pH levels (1, 4, 7, 10 and 13). The marine environment was simulated in the laboratory by adding 3.5% NaCl to the tap water. Designed quantity of sulphuric acid was added to salt solution to maintain pH of 1 and 4 in marine environment. Similarly, designed quantity of sodium hydroxide was added to the salt solution to maintain pH of 10 and 13 in marine environment. The specimens were exposed for the durations of 60 and 90 days. The resistance of concrete to marine environment with varying pH was measured through compressive strength retention and ultimate bond strength retention in steel fibre reinforced concrete. The addition steel fibres reduced workability of concrete, especially 1.5% of steel fibres yielded considerably low slump value. The ultimate bond strength and compressive strength values increased due to the addition of steel fibres. The pH of the marine environment has a significant influence on the compressive strength retention and bond strength retention. Exposure to marine environment with pH 1 underwent severe loss in compressive strength and ultimate bond strength with very low strength retention values. However, exposure to marine environment with pH 10 and 13 had minimal strength losses with higher values of compressive strength and ultimate bond strength retention. The alkaline nature of marine environment was not susceptible to strength reduction when compared to neutral (pH 7) and acidic (pH 1) marine environment. The steel fibre reinforced concrete performed better in acidic marine environment compared to control concrete without steel fibres. © Springer Nature Singapore Pte Ltd. 2019.