Journal of Research of the Taiheiyo Cement Corporation
Online ISSN : 2759-6826
Print ISSN : 1344-8773
ISSN-L : 1344-8773
Volume 2020, Issue 178
Displaying 1-8 of 8 articles from this issue
  • Takao OCHIAI, Hiroyuki HAYANO
    2020 Volume 2020 Issue 178 Pages 3-11
    Published: June 30, 2020
    Released on J-STAGE: January 24, 2025
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS
     The purpose of this study was to quantitatively evaluate the strain dispersion effect of alkali-resistant glass fiber net by using digital image correlation method. A full-scale test piece with an opening was exposed outdoors, digital images of the surface of the test piece were acquired with a line sensor type full-field strain measuring device, and the planar strain distribution was calculated by the digital image correlation method. By visualizing the planar tensile strain during the drying process, it was confirmed that the alkali-resistant glass fiber net was capable of dispersing the local strains induced at the corners of the opening and suppressing the occurrence of cracks. In addition, the strain dispersion effect was quantitatively expressed by the change in the frequency distribution of the maximum principal strain before crack initiation.
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  • Katsuya KONO, Ryota SONE, Yusuke KURIHASI, Masato KOMURO, Norimitsu KI ...
    2020 Volume 2020 Issue 178 Pages 12-23
    Published: June 30, 2020
    Released on J-STAGE: January 24, 2025
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS
     In order to investigate impact resistance behavior of steel fiber reinforced porosity free concrete (PFC), a newly developed ultra-high-strength concrete with a compressive strength of 400 N/mm2, falling-weight impact tests were conducted on PFC panels, taking the mixing ratio of steel fibers and the falling height of the weight as variables. The tests were also conducted using high-strength concrete (HC) panels with a compressive strength of 100 N/mm2 to investigate the effects of compressive strength on the impact resistance behavior of concrete panels. The following findings were obtained from this experimental study: 1) impact resistance capacity of the PFC panels with 2 vol.% of steel fibers was significantly higher than that of the HC panels with the same ratio of steel fibers; and, 2) the improved bonding between the dense PFC matrix and steel fibers contributed to improving the impact resistance.
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  • Toshio IMAI
    2020 Volume 2020 Issue 178 Pages 24-36
    Published: June 30, 2020
    Released on J-STAGE: January 24, 2025
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS
     Rotary kilns equipped with cyclone preheaters are very commonly used at modern cement plants. The system is excellent in energy efficiency, but has a problem of frequent clogging of the cyclones. With the increasing use of waste tires as alternative energy at the kiln inlet (the cool end), clogging of cyclones has become a crucial issue for stable kiln operation. In order to identify the clogging mechanism, the authors investigated the effects of alternative energy and raw meal used in the kiln inlet on the circulations of sulfur (S), chlorine (Cl) and potassium (K) and on the coating growth. It was found that, when combustible waste containing sulfur was directly fed to the kiln inlet, the volume of gaseous SOx passing through the kiln inlet increased as a result of direct combustion of the waste in addition to vaporization of sulfur from raw meal in a hot kiln due to enhanced reduction. This accelerated formation of low melting point minerals such as sulphate spurrite [2(2CaO・SiO2)・CaSO4] and the ellestadite group [Ca10(SiO4)3(SO4)3(OH,F,Cl)2], which led to increased clogging of the cyclones. It was also suggested that direct use of aluminum- containing alternative raw meal at the kiln inlet could be another cause of coating growth through formation of mayenite (Ca12Al14O33 ) and wadalite (Ca6Al5Si2O16Cl3).
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  • Akiya OKADA, Yasuhiro NAGASHIO
    2020 Volume 2020 Issue 178 Pages 37-45
    Published: June 30, 2020
    Released on J-STAGE: January 24, 2025
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS
     This paper deals with the durability of rapid hardening concrete made by adding a rapid hardening admixture to ordinary concrete with a different design strength. A five-year outdoor exposure test was carried out in Hokuto City, Hokkaido, for the evaluation of the durability. The rapid hardening concrete in this study after 5 years of outdoor exposure showed no deterioration attributable to frost damage. It was also found that, compared to plain concrete with an air content of about 5%, the rapid hardening concrete had a lower cumulative pore volume and a more densely packed microstructure, being superior in compressive strength, surface quality and resistance to carbonation and chloride ion penetration. The results also showed that the hydration products inside the concrete were in sound condition after 5 years of outdoor exposure.
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  • Atsushi NAKAMURA, Kenichi HONMA, Tomohisa YOSHIKAWA, Ryohei UESUGI, Ya ...
    2020 Volume 2020 Issue 178 Pages 46-53
    Published: June 30, 2020
    Released on J-STAGE: January 24, 2025
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS
     With the pervasion of next-generation vehicles and private solar power storage systems, there will be considerable amounts of spent lithium-ion batteries (LIBs) to be disposed of. Some rare and base metals can be recovered by dismantling and sorting, but with significant risks of fire and leakage of hazardous chemicals. To solve this issue, a safe and efficient recycling system must be established. The most essential technology in the system is the roasting. A pilot-scale roasting furnace was placed in a cement manufacturing plant under commercial operation, and test operations were conducted for verification. The results showed that roasting under low oxygen conditions at around 450℃ achieved highly efficient separation and recovery of useful metal resources, without melting aluminum used in LIBs. It was also confirmed that hydrogen fluoride contained in the exhaust gas from roasting could be detoxified by introducing the exhaust gas into the clinker cooler extraction air of the cement manufacturing facility. The proposed system was demonstrated to be capable of safely recycling difficult-to-handle spent LIBs in large quantities at low costs.
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