Journal of Advanced Concrete Technology
Online ISSN : 1347-3913
ISSN-L : 1346-8014
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Invited paper
  • Toshiki Ayano, Takashi Fujii
    2021 Volume 19 Issue 2 Pages 118-132
    Published: February 19, 2021
    Released: February 19, 2021

    A high volume of ground granulated blast furnace slag (GGBS) or granulated blast furnace slag (BFS) can enhance the resistance of concrete to freezing and thawing without the use of air-entraining (AE) agents. Furthermore, it can also enhance the resistance of concrete to chloride ion penetration and sulfuric acid attack, although the mechanism of improvement differs. In particular, BFS can reduce time-dependent strains, such as drying shrinkage strain and creep strain. The use of granulated blast furnace slag, either GGBS or BFS, promotes the durability of concrete structures by improving the mechanical properties of cementitious materials. Some of the concrete properties that are improved by the incorporation of BFS are presented in this paper. The detailed improvement mechanism of BFS has not yet been clarified. However, it is clear that it depends on the chemical reactions involving BFS and thus a critical time is required for BFS to hydrate in order to improve concrete properties. It takes four weeks to achieve high resistance to freezing and thawing by using BFS without the addition of an AE agent; use of a thickening agent can further shorten this curing period to one week. This paper is an English translation from a previous work by the authors [Ayano et al., (2014). “Resistance to freezing and thawing attack of concrete with blast furnace slag fine aggregate.” Journal of Japan Society of Civil Engineers, Ser. E2 (Materials and Concrete Structures), 70(4), 417-427 (in Japanese)] and [Jariyathitipong et al., (2013). “Improvement of resistance to sulfuric acid attack of concrete by use of blast furnace slag sand.” Journal of Japan Society of Civil Engineers, Ser. E2 (Materials and Concrete Structures), 69(4), 337-347 (in Japanese)].

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Technical report
  • Keitai Iwama, Yushi Kato, Shigeaki Baba, Kazuaki Higuchi, Koichi Maeka ...
    2021 Volume 19 Issue 2 Pages 106-117
    Published: February 09, 2021
    Released: February 09, 2021

    Spilling out of condensed liquid water from needle-like holes in high-strength concrete was experimentally observed under fire attack. The presence of these holes was found to prevent explosive spalling effectively in the vicinity of the holes during fire exposure tests. This spilling out occurred at about 10 to 30 minutes after the start of high temperature heating. These needle-like holes are defined herein as local weaknesses that may act as rapid paths of water permeation to reduce the risk of explosive spalling of cover concrete. The phase change of moisture from CSH solids to condensed liquid as well as free water in micro-pores was simulated by a multi-phase chemo-physics analysis of ultra-high-strength concrete. The prediction of the high-rate phenomena was experimentally proved by using embedded moisture sensor, and the high-rate discharge of condensed water though local weaknesses was analytically simulated.

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Scientific paper
  • Sanjay R. Salla, Chetankumar D. Modhera, Uppara Raghu Babu
    2021 Volume 19 Issue 2 Pages 133-148
    Published: February 25, 2021
    Released: February 25, 2021

    The current era shows that innovation and reuse of industrial by-products are necessary to protect the environment and sustainable development. The production of cement highly harms the environment in terms of CO2 emissions. Cement production contributes to nearly 5.0% of the global pollution that is induced by CO2 emissions. The present study shows the role of supplementary cementitious materials (SCMs) in construction industries. The two different SCMs, namely cinder and processed granulated ground blast furnace slag (GGBS), were used to replace cement. Different blends were prepared by replacing ordinary Portland cement (OPC) with cinder up to 70% intervals of 10% and up to 50% of processed GGBS at 5% intervals. The different tests were conducted like specific gravity, setting time, fineness, and compressive strength of different prepared blends to ensure the pozzolanic reactivity of SCMs. X-ray fluorescence (XRF) test results showed that available oxides like calcium, silica, aluminum, and iron oxides are suitable for replacing cement with cinder and processed GGBS. In addition to these, to find out possible optimum among the various prepared blends, techniques for order performance by similarity to ideal solution method was adopted. Cost analysis shows that the overall cost of material can be reduced by 16%. Energy analysis shows that cinder and processed GGBS could reduce energy consumption by 24.56% and 3.6%, respectively.

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  • Christa E. Torrence, Alain B. Giorl, Yujie Li, Elena Tajuelo Rodrigue ...
    2021 Volume 19 Issue 2 Pages 149-167
    Published: February 27, 2021
    Released: February 27, 2021

    As the nuclear fleet in the United States ages and subsequent license renewal applications grow, the prediction of concrete durability at extended operation becomes more important. To address this issue, a Fast-Fourier Transform (FFT) method is utilized to simulate aging-related degradation of concrete within the Microstructure Oriented Scientific Analysis of Irradiated Concrete (MOSAIC) software. MOSAIC utilizes compositional phase maps to simulate damage from radiation-induced volumetric expansion (RIVE), applied force, creep, and thermal expansion. This compositional detail allows each mineral in the microstructure to be assigned specific material properties, allowing the simulation to be as accurate and representative as possible. The principal goal of MOSAIC is to simulate the effects of nonlinear aging mechanisms occurring in nuclear concrete on the macroscopic mechanical properties, using only the aggregate microstructure compositional information as a starting point. Several realistic example simulations are shown to demonstrate the utility and uniqueness of the MOSAIC software.

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