Faculty Publications

Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736

Publications by NITK Faculty

Browse

Subject: search.filters.subject.Portland cement

Search Results

Now showing 1 - 10 of 34
  • No Thumbnail Available
    Item
    Effect of addition of OPC on Performance characteristics of Self-compacting Alkali activated slag concrete mixes
    (Institute of Physics Publishing helen.craven@iop.org, 2019) Manjunath, R.; Narasimhan, M.C.
    An attempt has been made in the present research to develop construction friendly, self-compacting, alkali-activated slag concrete mixes with ground granulated blast furnace slag (GGBFS) as the major source of binder material. In an effort to make the concrete mixes more eco-friendly and sustainable, by-products from Iron and Steel Industry such as steel slag sand and Electric Arc Furnace (EAF) slag aggregates, were used as the fine and coarse aggregates respectively. While the total binder content has been varied in the range of 700 - 800 kg/m3 (in increments of 50 kg/m3), all the trial mixes had a constant w/b ratio of 0.40. Different amounts of sodium silicate solutions, with specified amounts of sodium hydroxide flakes dissolved in them, are used as alkaline solutions, with the combined Na2O percentage in them varying between 6% - 8%. Test specimens were cast with mixes which showed enhanced flow-properties as per relevant EFNARC guidelines and were tested for their mechanical strength and durability characteristics. Effect of admixing of ordinary Portland cement (OPC) in smaller percentages (2.5% - 10 %, in increments of 2.5%), on the performance characteristics of this novel class of AAC mixes is evaluated. Increased cement contents are found to lead to better flow ability properties and higher strengths values with lower sorptivity values in all the Cement-Admixed, Self-compacting, Alkali-Activated Slag Concrete mixes (CASAASC mixes) tested herein. Studies with a scanning electron microscope have shown more densified morphologies developed, accounting for better performances of these mixes. © 2019 IOP Publishing Ltd. All rights reserved.
  • No Thumbnail Available
    Item
    Experimental Studies on the Mechanical and Durability Properties of Mortar Containing Waste Glass Powder as Partial Replacement of Cement
    (Springer Science and Business Media Deutschland GmbH, 2024) Chopra, S.; Kuttagola, K.; Prashanth, M.H.
    It is well known that Portland cement production is an energy-intensive industry, being responsible for about 5% of the global anthropogenic carbondioxide emissions worldwide. An important contribution to the sustainability of concrete and cement industries consists of using pozzolanic additions, especially if obtained from waste such as waste glass. In the present study, crushed waste glass was used in mortar as a partial cement replacement (0, 5, 15, 25, 35, and 45%) material to ascertain applicability in concrete. Experimental studies were carried out to determine mechanical properties like compressive strength and split tensile strength and durability properties by immersing mortar in 5% sulphuric acid and hydrochloric acid solution. Experimental results indicate better mechanical properties of mortar with 15% replacement of cement by glass powder. Further, with 15% replacement of cement by glass powder has shown better resistance to sulphuric acid attack and weight loss is comparable to weight loss in normal mortar in sulphuric acid and thus 15% replacement of cement can be considered as optimum dosage of glass powder in concrete. Also, glass powder replacement above 35% have performed poorly in all tests except in tensile strength test. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
  • No Thumbnail Available
    Item
    Experimental studies on the effects of corrosion on the flexural strength of RC beams
    (CAFET INNOVA Technical Society cafetinnova@gmail.com 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2014) Pandit, P.; Venkataramana, K.; BabuNarayan, K.S.; Parla, B.; Kimura, Y.
    RC structures are generally very durable and are capable of withstanding a variety of adverse environmental conditions. However, failures of these structures still occur and reinforcement corrosion is one of the major causes. In the present research, corroded Ordinary Portland Cement (OPC) beams were tested in the laboratory to evaluate their flexural behavior. Accelerated corrosion technique was adopted to corrode the beams. The corrosion was measured using Applied Corrosion Monitoring (ACM) instrument. From the results, it is seen that, as the rate of corrosion increases, the load carrying capacity decreases. The deflection increases initially and then decreases. It is observed that the stiffness of the beams is reduced when rate of corrosion is increased due to changes in the modulus of elasticity of corroded steel. © 2014 CAFET-INNOVA TECHNICAL SOCIETY.
  • No Thumbnail Available
    Item
    Flexural bond strength behaviour in OPC concrete of NBS beam for various corrosion levels
    (Techno-Press, 2014) Shetty, A.; Venkataramana, K.; Babu Naraya, K.S.
    Corrosion is one of the primary reasons why structures have limited durability. The present investigation is carried out to study the behavior of RC (Reinforced Concrete) structural members subjected to corrosion. Experimental investigations were carried out on National Bureau of Standard (NBS), RC beam specimens made of Ordinary Portland Cement (OPC) concrete. Load versus deflection behaviour was studied for different levels of corrosion i.e., 2.5%, 5%, 7.5% and 10%. It is observed that for every percentage increase in corrosion level, there is about 1.6% decrease in load carrying capacity. Also as the amount of corrosion increases there is a reduction in bond stress. Copyright © 2014 Techno-Press, Ltd.
  • No Thumbnail Available
    Item
    Recuring studies on concretes subjected to elevated temperatures and suddenly cooled by water quenching
    (Multi-Science Publishing Co. Ltd, 2015) Yaragal, S.C.; Kittur, M.M.; Babu Narayan, K.S.
    Concrete is found to undergo degradation when subjected to elevated temperatures during an accidental event, such as fire and lose substantial amount of its original strength. The loss of strength in concrete is mainly attributed to the decomposition of Calcium Silicate Hydrate (C-S-H) and release of chemically bound water, which begins when the exposure temperature exceeds 500°C. When such a concrete is supplied with water and allowed to recure, it is found to recover substantial amount of its lost strength. This work is carried out to investigate the effect of recuring on strength recovery of un-blended and blended concrete specimen (100 mm cubes) subjected to elevated temperatures from 400°C to 700°C, in steps of 100°C, for a retention period of two hours at the designated temperatures. The concrete cubes immediately after exposure were subjected to thermal shock by quenching them in water, and then temperature of thermally shocked concrete is allowed to cool to room temperature. The cooled specimen were then recured in water for 1, 3, 7, 14, 21, 28, 56 days and tested for compressive strength recovery. These studies were carried out for Portland Cement (PC) based concrete and Portland & Granulated Blast Furnace Slag (70% PC + 30% GGBS) based concrete (blended concrete), and some interesting results are presented and discussed in this paper. © 2015, Multi-Science Publishing Co. Ltd. All rights reserved.
  • No Thumbnail Available
    Item
    Air-cured Alkali activated binders for concrete pavements
    (Chinese Society of Pavement Engineering, 2015) Palankar, N.; Ravi Shankar, A.U.; Mithun, B.M.
    The present study focuses on the possibility of use of alkali activatedbinders for use in concrete pavements. Alkali Activated Slag Concrete (AASC) and Alkali Activated Slag Fly ash Concrete (AASFC) are prepared and the properties are compared with Ordinary Portland Cement Concrete (OPCC). The Ground Granulated Blast FurnaceSlag (GGBFS) and Fly Ash (FA) are blended in the ratios 100:0, 75:25, 50:50 and 25:75 as binder and activated using strong alkaline solution. Trial mixes are carried out to identify the optimal Activator Modulus (Ms) for each combination of GGBFS and FA. The mix design for the optimal activator modulus is optimised to achieve sufficient strength for Pavement Quality Concrete (PQC) and the fresh and mechanical properties are studied in detail. The results indicate the properties of AASC and AASFC are similar or slightly better than conventional OPCC and satisfy the minimum strength requirements for concrete pavements. The application of alkali activated binders will minimise the environmental hazards occurring from augmented OPC production, along with effective utilisation of industrial waste materials and conservation of natural resources. © Chinese Society of Pavement Engineering.
  • No Thumbnail Available
    Item
    Performance of alkali activated slag concrete mixes incorporating copper slag as fine aggregate
    (Elsevier Ltd, 2016) Mithun, B.M.; Narasimhan, M.C.
    In this present study, copper slag (CS) is proposed as an alternative to river sand as fine aggregate in alkali-activated slag concrete (AASC) mixes. The relative performance of alkali activated slag concrete mixes with CS as fine aggregate is compared to conventional Ordinary Portland Cement concrete (OPCC) mix in terms of their workability, strength and durability parameters. The results indicate that, AASC mixes with CS, as a replacement to sand upto 100% (by volume), show no marked loss in strength characteristics. AASC mixes with either sand or CS possess similar modulus of elasticity, lower total porosity, lesser water absorption and reduced chloride ion penetration as compared to OPCC. Strength-retention characteristics of AASC mixes with sand/CS on exposure to sulphate and acid-rich environment are also studied. Use of AASC mixes for structural application reduces carbon footprint, decreases water consumption and cost. Use of CS as fine aggregate reduces river sand consumption as an added benefit. © 2015 Elsevier Ltd. All rights reserved.
  • No Thumbnail Available
    Item
    Durability studies on eco-friendly concrete mixes incorporating steel slag as coarse aggregates
    (Elsevier Ltd, 2016) Palankar, N.; Ravi Shankar, A.U.; Mithun, B.M.
    The present study discusses the durability performance of alkali activated concrete mixes containing steel slag as coarse aggregates. Steel slag aggregates, a waste product obtained from iron and steel industry are incorporated as coarse aggregates in alkali activated slag concrete (AASC) and alkali activated slag fly ash concrete (AASFC) by replacing traditional natural aggregates. The mix design for AASC and AASFC mixes are optimised to obtain sufficient strength for structural purposes and then steel slag coarse aggregates are incorporated at different replacement levels (0%, 50% and 100% by volume of total coarse aggregate content). Durability properties such as long term ageing performance, water absorption, volume of permeable voids, resistance to sulphuric acid attack and resistance to magnesium sulphate attack are studied in detail and compared with conventional Ordinary Portland Cement Concrete (OPCC). The ecological and economical analysis of concrete mixes is also carried out. It was found that the AASC and AASFC mixes displayed better durability performance as compared to OPCC. The inclusion of steel slag aggregates slightly reduced the durability performance of AASC and AASFC mixes. The AASC and AASFC with steel slag aggregates displayed lower energy requirement and lower production cost as compared to OPCC, thus proving it to be eco-friendly. © 2016 Elsevier Ltd. All rights reserved.
  • No Thumbnail Available
    Item
    Interface bond strength of ultra-thin whitetopping (UTW) and hot mix asphalt (HMA) composites by direct shear
    (ASTM International, 2017) Suresha, S.N.; Satish, D.
    Whitetopping is a portland cement concrete (PCC) overlay that is constructed on the top of existing bituminous or hot mix asphalt (HMA) pavement. The design and construction of UTW over HMA enables the composite to act as a monolithic layer. This article presents the findings of a laboratory study performed on interface shear strengths of UTW and HMA composites by direct shear approach. The objectives of the study were to evaluate the main effects of (i) different interface treatments, (ii) variation in the design binder content of HMA, and (iii) temperature conditioning and moisture conditioning on the interface shear strength. Based on the results of interface shear strength tests, the range of bond strength of UTW-HMA was found to be 0.22-1.29 MPa. Other factors like age of UTW, temperature conditioning, and moisture conditioning also had significant effects on the interface shear strengths of UTW-HMA composites. © Copyright 2017 by ASTM International.
  • No Thumbnail Available
    Item
    Enhancement of the properties of fly ash based geopolymer paste by incorporating ground granulated blast furnace slag
    (Elsevier Ltd, 2017) Saha, S.; C, C.
    Research efforts have been made continuously to establish fly ash based geopolymer as an alternative binder material for the production of fresh concrete because production of Ordinary Portland Cement degrades the environment by huge emissions of carbon-di-oxide and also by consuming lot of natural resources. But most of the study reveals, fly ash based geopolymer paste needs more time to get set when it is cured at ambient temperature. As a result, it is quite impractical to use fly ash based geopolymer paste as an alternative to Ordinary Portland Cement in faster construction. In this study, an effort has been made to enhance the properties of fly ash based geopolymer paste by incorporating ground granulated blast furnace slag at various percentage levels. Microstructure of the geopolymer paste is studied using Scanning Electron Microscopy. Result of this investigation shows that significant improvement on setting time and compressive strength can be obtained by adding ground granulated blast furnace slag in the mixes. © 2017 Elsevier Ltd