| 種別 | paper |
| 主題 | The Influence of Medium and High Temperature Environments(20~50℃)on the Physical Properties of High Strength Concrete |
| 副題 | |
| 筆頭著者 | Huhammad Fauzi（Kyushu University） |
| 連名者1 | Yasunori MATSUFUJI（Kyushu University） |
| 連名者2 | Tomoyuki KOYAMA（Kyushu University） |
| 連名者3 | Mikio NAKATAKE（Kyushu University） |
| 連名者4 | |
| 連名者5 | |
| キーワード | |
| 巻 | 16 |
| 号 | 1 |
| 先頭ページ | 705 |
| 末尾ページ | 710 |
| 年度 | 1994 |
| 要旨 | 1. INTRODUCTION. Long-term high temperatures such as those found in power plants and chemical plants can increase the temperature on the surface of concrete member up to 50℃. In hot weather, where the temperature is almost around 35℃,the strength maintenance for outer layer of high-strength or high quality concrete is important both for theoretical and practical reasons. Firstly, the corrosion of steel reinforcement in concrete structures due to the carbonation is considered greater when the outer layer concrete cannot provide enough protection for early cracks after being exposed to those temperatures for certain time. Therefore, the effective means of protecting the steel reinforcement is to prepare an adequate cover and maintain the strength of that cover (outer layer concrete). Secondly, it will provide useful informations in maintaining the quality of high-strength concrete under medium and high temperature environments. This preliminary study deals with the influence of medium and high temperature, within the range of 20℃ to 50℃, on the properties of high-strength concrete made with four types of concrete mixes. 4. CONCLUSION The following preliminary conclusions seem reasonable based on the results of this study concerning the influence of medium and high temperature environments on the physical properties of high-strength concrete. 1) The compressive strength of wet-wrapped curing which has been assumed as inner concrete were usually greater than dry air curing (outer layer concrete). Comparing to the inner concrete, the loss of strength of the outer layer concrete from age of the 7 days, was around 70%. This may suggest that, in order to maintain the strength of outer layer concrete, sufficient curing method such as spraying with water or covering with wet sheet on the concrete member is necessary 2) The concrete specimens incorporated with mineral admixtures produced greater strength from the age of 7 days. This indicated that the significant accelaration pozzolanic reaction of those admixtures at medium and high temperatures will increase the strength. 3) For normal concrete, the static modulus of elasticity at compressive strength of 200kgf/cm2 was about 2.1×105kgf/cm2. However, as observed in this study, the static modulus of elasticity of high-strength concrete was between 3.2 to 4.8×105kgf/cm2. 4) The dynamic modulus of elasticity of all concrete mixes increased continuously with age under 20℃ of water and wet-wrapped curing but decreased from the age of 28 days under dry air curing. The ratios of dynamic modulus of elasticity from the age of 7 days were between 5.04 to 5.34×105kgf/cm2. |
| PDFファイル名 | 016-01-1116.pdf |