著者

川瀬 翔太 大塚 秀三 赤谷 樹一郎 竹村 雅行 遠野 未来 荒巻 卓見

出版者

日本建築仕上学会

雑誌

日本建築仕上学会 大会学術講演会研究発表論文集 2012年大会学術講演会研究発表論文集

巻号頁・発行日

pp.54, 2012 (Released:2013-09-03)

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本報の目的は、伝統工法による版築壁の圧縮強度および形状変化に及ぼす調合および施工要因の影響を明らかにすることを目的とした。その結果、以下の結論が得られた。圧縮強度が最大になる構成割合は,荒木田土,細骨材および消石灰の質量比が1:0.5:0.15であり,体積変化率を考慮するとMgCl2水溶液の濃度が15%である。圧縮強度が最大となる施工要因は,ランマーの落下高さ30cm,締固め回数25回,脱型材齢7日および気中養生である。締固めエネルギーに伴う圧縮強度は,概ね200×103~300×103J/cm3の間で最大となり,それ以降は減少する。養生方法に伴う圧縮強度は,いずれの養生方法とも材齢の経過に伴い増加するが,封かん養生より気中養生の方が大きくなる。

著者

荒巻 卓見 中田 善久 大塚 秀三 宮田 敦典

出版者

一般社団法人 日本建築学会

雑誌

日本建築学会技術報告集 (ISSN:13419463)

巻号頁・発行日

vol.27, no.65, pp.58-63, 2021-02-20 (Released:2021-02-20)

参考文献数

11

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The purpose of study was to clarify the quality of plywood for concrete formwork with reuse of forms and the finish of concrete surface using reused plywood. In this study, an experiment on influence of reuse (up to 4 times) of plywood for conventional formwork at building construction site was carried out. Regarding the influence of reuse on the quality of plywood, bending strength, bending Young’s modulus, and surface roughness were investigated. In addition, the influence of reused plywood on gloss, color unevenness, and water absorption of the concrete surface was investigated. Moreover, in order to confirm the influence of reuse of plywood at construction site, the results of this experiment at building construction site were compared with the results of laboratory experiment conducted so far.

著者

荒巻 卓見 中田 善久 大塚 秀三 手島 基 宮田 敦典

出版者

一般社団法人 日本建築学会

雑誌

日本建築学会技術報告集 (ISSN:13419463)

巻号頁・発行日

vol.20, no.44, pp.13-18, 2014-02-20 (Released:2014-02-20)

参考文献数

14

被引用文献数

2 3

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This study purposed for prehension about the actual situation of work from the viewpoint of formwork contractors. In this paper, we conducted a questionnaire survey about concrete form plywood, strength and rigidity of form, and formwork based on the experience of formwork carpenters in Kanto region. As a result, it elucidated the actual situation of work, concrete form plywood, strength and rigidity of form, and formwork in the construction site.

著者

中田 善久 斉藤 丈士 梶田 秀幸 大塚 秀三 春山 信人

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.82, no.738, pp.1145-1154, 2017 (Released:2017-08-30)

参考文献数

17

被引用文献数

3 4

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The authors have carried out the experiments to identify the effects on fluidity, resistance to segregation, strength, Young's modulus, dry shrinkage and durability of high-strength concrete when unit water content was varied in high-strength concrete while unit bulk volume of coarse aggregate was fixed, or the volumetric ratios of cement paste and fine aggregate were varied. Three types of cement, ordinary Portland cement, moderate-heat Portland cement and low-heat Portland cement, were used. Limestones were adopted as coarse aggregate. Water-cement ratio was varied with 45, 35 and 25%. Analysis were carried out in concern with properties of fresh concrete, properties of concrete hardening, and properties of hardened concrete where unit water content was varied. When water-cement ratio was 35%, changes in the properties of high-strength concrete with hard sandstones used as coarse aggregate owing to the increase of unit water content were also examined. As a result of the experiments, it was found that increasing of the water content caused no segregation of materials, facilitation of handling, reducing of changes in the retention of slump and slump flow, increasing of flow velocity in L-box tests and increasing of bleeding only slightly. Few effects were observed on the initial properties and on the properties of hardened concrete. Based on the above, it is assumed that slightly increased unit water content in the range between 5 to 10 kg/m3 in high-strength concrete with fixed unit bulk volume of coarse aggregate will improve construction performance without great affection of the quality parameters while the deterioration of the parameters has been afraid when unit water content was increased.

著者

宮田 敦典 中田 善久 大塚 秀三

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.83, no.751, pp.1217-1227, 2018 (Released:2018-09-30)

参考文献数

38

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It is significant to accurately grasp the pressure loss per unit length of pipeline in calculating total pressure of pipeline. The standard value of pressure loss per unit length of pipeline is shown in recommendation for practice of placing concrete by pumping methods. The standard value of pressure loss per unit length of pipeline were obtained from pumping experiment conducted around 1970. But, mix-proportion and concrete materials has changed compared to the 1970s. Especially, design strength has risen compared to the 1970s, and high-range AE water reducing agent was developed and has spread. Therefore, concrete that has been used recently can't apply the standard value of pressure loss per unit length of pipeline. So this study aimed to reveal influence of mix-proportions on the pressure loss per unit length of pipeline by literature survey and pumping experiment. In the first, we studied the influence of water-cement ratio on the pressure loss per unit length of pipeline. Pressure loss per unit length of a pipe tended to be roughly proportional to the square of cement-water ratio. Next, we examined pressure loss per unit length of pipeline for each slump of concrete that more than W/C 45%, and we examined pressure loss per unit length of pipeline for each unit water content of concrete that less than or equal to W/C 45%. As a result, pressure loss per unit length of pipeline tended to increase when slump decrease and unit water content is low. And we derived the relational expression between pressure loss per unit length of pipeline and true output capacity. In additions, this paper proposed standard value of pressure loss per unit length of pipeline of concrete that more than W/C 45% on the basis of literature survey results. Finally, we confirmed the validity of the relational equation obtained from literature survey by pumping experiment. This paper shows a result of pressure loss per unit length of pipeline of concrete with normal portland cement. Therefore, we should does experiment of test pumping with reference to result of this paper when we use concrete with cement and materials other than normal portland cement.

著者

中田 善久 斉藤 丈士 梶田 秀幸 大塚 秀三 春山 信人

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.83, no.748, pp.751-761, 2018 (Released:2018-06-30)

参考文献数

14

被引用文献数

3

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The authors have carried out experiments to identify the effects on fluidity, separation resistance, strength, Young's modulus, drying shrinkage and durability of high-strength concrete when sand-total aggregate ratio was varied. In high-strength concrete while water-cement ratio and cement-paste volume was fixed, that is, volumetric ratios of coarse aggregate and fine aggregate were varied. Three types of cement, normal portland cement, moderate-heat portland cement and low-heat portland cement, were used. Limestones and sandstones were adopted as coarse aggregate. Water-cement ratio was fixed as 35%. Unit water content was fixed as 170kg/m3. Analysis were carried out in concern with properties of fresh concrete, properties of concrete hardening, and tendency of properties of concrete where sand-total aggregate ratio was varied. As a result of the experiments, If sand-total aggregate ratio is smaller than general range, impression of state of fresh concrete tends to be somewhat impaired, but even if sand-total aggregate ratio is somewhat larger than general range, impression of state of fresh concrete is it was not compromised. However, when sand-total aggregate ratio is large as addition rate of high-performance AE water-reducing agent is significantly large, impression of state is impaired due to separation of fresh concrete in addition to increase in bleeding and delay of settling-time. In hardened concrete, influence of sand-total aggregate ratio on compressive strength is small, As sand-total aggregate ratio is larger, tendency of young's modulus to slightly decrease, tendency of length change by drying to slightly increase, tendency of carbonation depth to slightly increase. Based on the above, high-strength concrete may possibly obtain hardened concrete of required quality even if sand-total aggregate ratio is increased somewhat within range where separation resistance is not impaired in consideration properties of fresh concrete.