Department of Civil Engineering

Permanent URI for this collectionhttp://localhost:4000/handle/123456789/1927

Browse

Has files: NoSubject: search.filters.subject.Concrete

Search Results

Now showing 1 - 10 of 26
  • No Thumbnail Available
    Item
    Temperature, porosity and strength relationship for fire affected concrete
    (Springer, 2022-02) Barai, Sudhir Kumar
    In a fire incident, structural members are mostly unevenly exposed to temperatures and consequently suffer uneven damage. To rehabilitate and restore these for future usage, it is essential to correctly map the temperature field that the structural elements were subjected to during fire events. The majority of the existing relationships for temperature prediction apply to reinforced concrete beams only. In the present study, a material-porosity-based approach is proposed. Normal and high strength concrete structural elements were exposed to a range of elevated temperatures, and reserved compressive strength was evaluated. Another set of the same specimens were used to determine porosity using four techniques. Based on the observations, correlations among temperature, strength, and porosity for normal and high strength concrete are proposed. The suggested methodology and expressions may be used to predict the reserved strength and temperature field that the structural elements may have been exposed to, based on the evaluated porosity of concrete. Back-scattered electron Imaging was found to be the most fitting method for porosity evaluation.
  • No Thumbnail Available
    Item
    Methodology for Predicting the Structural Response of FRP-Concrete Composite Beams Using Abaqus/CAE Software Package
    (Springer, 2022-07) Singh, Shamsher Bahadur
    A Fiber Reinforced Polymer (FRP)-Concrete composite beam system comprises of several contact interactions, sub-components with varying geometries, and complex material behavior. Evaluating the flexural response of such structures through experimental campaigns is highly expensive and time-consuming as obtaining the desired output variables requires the specimens to be heavily and precisely instrumented. A numerical simulation could provide a much better alternative in this case as it can simulate the complete mechanical response of the physical system with relatively much ease and economy. However, the complexities involved with the problem regarding contact interactions and complex material behavior, make such analysis suffer from several convergence difficulties. The chapter is an attempt to overcome these difficulties by establishing a methodology that can be followed for modeling and analyzing such structures.
  • No Thumbnail Available
    Item
    Reliability-based mix design of marble dust incorporated concrete and its assessment using the concept of performance index
    (Wiley, 2022-03) Srivastava, Anshuman
    Concrete is one of the most important and versatile construction materials and variation in its properties is inevitable. Mix design of concrete is done in such a way that the design compressive strength is typically higher than the actual values specified by the structural engineer. The concept of reliability has not been explicitly used in regard of calculation of compressive strength using mix design and demands attention. A design procedure based on the reliability-based index is presented. The design procedure is developed for the concrete mix with partial replacement of cement by marble dust. The mechanical property which is the compressive strength of the concrete mix design is considered as a random variable, assumed to be lognormally distributed. The present study makes an effort to design a concrete mix in accordance to theory of confidence level for various levels of reliability. Mix design guidelines and graphs for various levels of replacement of cement by marble dust have also been presented in the study. Also, the cost analysis of various design mix proportions used has been calculated and compared. Four different cases to illustrate the performance rating in accordance with replacement levels of Marble dust have been formulated. The concrete mixes with marble dust induced in concrete had lower partial safety factors than those without inclusion. The characteristics of Marble dust incorporated concrete have been assigned numerical performance index values. These values may constitute a reliable means for concrete producers in finding the rate of cement replacement by other cementitious materials. The compressive strength of most of mixes with marble dust had a coefficient of variation and within-test coefficient of variation value ranging between 2% and 3% and less than 1.5%, respectively. This indicates toward improvement in quality of concrete with cement partially replaced by marble dust.
  • No Thumbnail Available
    Item
    Experimental investigation on paver blocks of fly ash-based geopolymer concrete containing silica fume
    (Taylor & Francis, 2021-12) Srivastava, Anshuman
    Utilisation of geopolymer may reduce the global warming potential of concrete. This study examines geopolymer concrete as interlocking paver blocks. Three concretes are compared: conventional cement, fly ash-geopolymer and fly ash–silica fume geopolymer. Sodium hydroxide solution is used in both geopolymer concretes, and sodium silicate solution is used in fly ash-based geopolymer concrete only. Rectangle and uni shape blocks are tested for compressive strength, flexural strength, abrasion resistance and freeze–thaw resistance. Dynamic drop loading test is conducted on block pavement with herringbone laying pattern . Results revealed that resistance to abrasion and water absorption of geopolymeris improved by adding silica fume . Freeze–thaw resistance is the lowest for cement concrete paver blocks. Lowest deflection occurred in block pavement of uni shape. Geopolymer concrete provides uniform load distribution than cement concrete. Cement concrete is slightly costlier than geopolymer concrete. This study concluded the geopolymer as suitable option for paver block applications
  • No Thumbnail Available
    Item
    Bioconcrete-Enabled Resilient Construction: a Review
    (Springer, 2023-03) Lahoti, Mukund; Srivastava, Anshuman
    Concrete, the ubiquitous cementitious composite though immensely versatile, is crack-susceptible. Cracks let in deleterious substances causing durability issues. Superseding conventional crack-repair methods, the innovative application of microbially induced calcium carbonate precipitation (MICCP) stands prominent, being based on the natural phenomenon of carbonate precipitation. It is eco-friendly, self-activated, economical, and simplistic. Bacteria inside concrete get activated by contacting the environment upon the crack opening and filling the cracks with calcium carbonate—their metabolic waste. This work systematizes MICCP’s intricacies and reviews state-of-the-art literature on practical technicalities in its materialization and testing. Explored are the latest advances in various aspects of MICCP, such as bacteria species, calcium sources, encapsulations, aggregates, and the techniques of bio-calcification and curing. Furthermore, methodologies for crack formation, crack observation, property analysis of healed test subject, and present techno-economic limitations are examined. The work serves as a succinct, implementation-ready, and latest review for MICCP’s application, giving tailorable control over the enormous variations in this bio-mimetic technique.
  • No Thumbnail Available
    Item
    Design and Performance Criteria for Fire-Resistant Design of Structures – An Overview
    (Springer, 2020-09) Muthukumar, G.
    Concrete, despite being inherently fire resistant, cannot be considered as a fire-proof material. It undergoes substantial variation in its characteristics during exposure to elevated temperatures. These variations may become hazardous for structural stability and serviceability depending upon the type and extent of exposure. Moreover, high-strength concrete, which is commonly used in tall buildings, may perform poorly against fire due to its high binder content and very low permeability. Despite all the aforementioned factors, fire resistance design of structural members has been given very restricted consideration in the current Indian practice. Although several standards provide guidelines to achieve fire safety in structures, the provisions for high-strength concrete and spalling prevention are not specifically available in the major international and national standards. This paper attempts to compare the provisions corresponding to fire-resistant design in Indian standard with the respective provisions of other country standards, e.g., ACI 216 [3], NZS 3101 [4], EN 1992–2 [8], etc. Comparison parameters primarily include the design requirements for various structural members to improve their fire resistance. Furthermore, suitable recommendations for Indian Codal provisions are attempted in the latter part of the paper to achieve superior performance under elevated temperatures.
  • No Thumbnail Available
    Item
    Recycled Aggregate Concrete: Particle Packing Method (PPM) of Mix Design Approach
    (Springer, 2019) Pradhan, Subhasis; Barai, Sudhir Kumar
    The reuse of old concrete as a source of aggregate is a reliable alternative to Natural Aggregate (NA) in concrete construction. Because of poor quality of Recycled Aggregate (RA), the performance of Recycled Aggregate Concrete (RAC) is not up to the mark in fresh stage and hardened stage as compared to Natural Aggregate Concrete (NAC). In this work, Recycled Coarse Aggregate (RCA) is replaced 100% to produce RAC. The Particle Packing Method (PPM) is proposed for the mix proportioning of concrete. In PPM, the smaller particles are selected to fill up the voids between large particles and so on. PPM is found out to be cost-effective than IS code method of mix design because of the requirement of lesser quantity of cement. The 7 and 28 days compressive strength of conventional concrete and RAC using PPM design mix are very similar. But, the increment in compressive strength from 28 to 90 days curing is higher for NAC than RAC
  • No Thumbnail Available
    Item
    Use of machine learning based technique to X-ray microtomographic images of concrete for phase segmentation at meso-scale
    (Elsevier, 2020-07) Barai, Sudhir Kumar; Pradhan, Subhasis
    The paper discusses the technical limitation of the gray value thresholding technique to detect the voids, aggregate and mortar phases. A two-stage image processing methodology is proposed for the segmentation of the three phases of concrete using the X-ray microtomographic images. In the first stage, the gray value thresholding technique is used to detect the voids. A machine learning based technique is proposed in the second stage for the segmentation of aggregate and mortar. The training data is used to model a planar decision boundary using the logistic regression method. For this, the radial distance from the centre of the image, gray value, and gray value of the filtered embossed image features are considered. The accuracy of the model to quantify the voids is validated with the commercial software. The machine learning model based on logistic regression method exhibits very good accuracy () in detecting the aggregate.
  • No Thumbnail Available
    Item
    Failure criteria of concrete- A review
    (TechnoPress, 2014-11) Muthukumar, G .; Kumar, Manoj
     Concrete is a versatile construction material used in many engineering structures. The design of concrete structures requires a thorough understanding of their material properties under various loading conditions. Several experimental investigations have been carried out to examine the behavior of concrete. This paper is an attempt to summarize the behavioral aspects of concrete under different loading conditions. Failure models developed out of these experimental investigations are reported in this paper with their merits and demerits.
  • No Thumbnail Available
    Item
    EFFECT OF SAND REPLACEMENT BY MILL SCALE ON THE PROPERTIES OF CONCRETE
    (International Journal of Engineering Technology Science and Research, 2015-03) Bhunia, Dipendu; Singhal, Anupam
    Concrete is the most widely used construction material in the world. This popularity of concrete carries with it an immense environmental cost. Billions of tons of natural materials are mined and processed each year to be used in concrete, which leaves a substantial mark on the environment. Efforts to use suitable recycled materials as substitutes for concrete aggregate are gaining in importance, such as recycled concrete aggregate, post-consumer glass, tires, etc. But one waste material which has not been extensively tested yet is mill scale. Mill scale is a flaky hazardous solid waste formed on the steel’s surface during the steel manufacturing processes. This work aims to evaluate the use of mill scale in Portland cement concrete, as a replacement for natural fine aggregates. Cement mortars with mix proportioning 1:3 were prepared varying the mill scale content of fine aggregate form 0% to 100%, for determination of compressive and tensile strength. The water/cement ratio used was 0.5 for all mix proportions. The compressive strength at different proportions did not give a general trend and two peaks were obtained at 60% replacement and 100% replacement. Maximum tensile strength was observed at 60% replacement of standard sand. A mix design was also done for M35 grade of concrete by the IS method. OPC of 43 grade was selected and sand replacement was done with mill scale varying from 0% to 80% with a suitable water cement ratio of 0.40. The compressive strength was measured after 28 days of completion of curing. Maximum strength was obtained for 40% sand replacement. Moreover, concrete with mill scale has demanded greater water content to maintain the workability.