著者

柴山 淳 西山 峰広

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.86, no.786, pp.1202-1212, 2021-08-30 (Released:2021-08-30)

参考文献数

24

被引用文献数

4

---

Geopolymer concrete has the potential to be an eco-friendly alternative to cement concrete because CO2 emissions in its production process can be reduced and industrial by-products such as fly-ash can be used effectively. The present study investigates flexural behavior of fly-ash based geopolymer concrete beams before yielding and its applicability as a flexural member. Eight beams consisting of four fly-ash based geopolymer concrete beams and four ordinary Portland cement concrete beams were cast and tested under four-point flexural loading. The experimental variables are combinations of reinforcing bar diameter and number of reinforcing bars, compressive strength and concrete types. In addition, non-linear three-dimensional finite element analyses were carried out. Bending moment-deflection behavior, crack width, crack space and number of cracks were examined. The experimental results were compared with the proposed equations provided by the AIJ design standard for reinforced concrete. The deflection and maximum crack width of the fly-ash based geopolymer concrete beams subjected to bending moment based on long/short-term allowable stress were similar to those of ordinary Portland cement concrete beams, and, therefore, they have an applicability as flexural members. The flexural behavior of fly-ash based geopolymer concrete beams prior to flexural yielding, except for the yielding deflection, could be predicted using the AIJ design standard. Making modifications to the coefficients related to the Young’s modulus ratio improved the accuracy of the prediction of yielding deflection. Although Young’s modulus of fly-ash based geopolymer concrete was lower than that of ordinary Portland cement concrete, the post-cracking stiffness of fly-ash based geopolymer concrete beams were not largely different from that of ordinary Portland cement concrete beams. The results suggested that the effect of tensile strength on the flexural behavior of the beams was greater than that of Young’s modulus of concrete. In addition, the crack width of the fly-ash based geopolymer concrete beams was similar to that of the ordinary Portland cement concrete beams, and could be predicted by the AIJ design standard for reinforced concrete.

著者

原田 和典 西山 峰広 山崎 雅弘 權 寧璡

出版者

京都大学

雑誌

挑戦的萌芽研究

巻号頁・発行日

2011

---

火災時の高強度コンクリートの爆裂は,発生機構が未解明の厄介な現象である。本研究では,空隙圧力と熱応力が複合して発生する応力が爆裂発生の原因であるとの仮説を立て,これを検証することを目的とした。外周圧縮実験と耐火加熱実験を行い,部分加熱時のように不均一な温度分布下で爆裂が起こりやすいこと、また爆裂に先立って亀裂が生じて空隙圧力が低下しても爆裂が生じることを示し、空隙圧力よりも熱応力の方が影響が大きいことを実験的に明らかにした。並行して熱伝導解析と弾性熱応力解析を行い、爆裂が生じた部分における熱応力の集中傾向を考察した。