| 種別 | paper |
| 主題 | Analytical Modelling for the Effect of Aggregates on Water Transport in Concrete |
| 副題 | |
| 筆頭著者 | Rajesh Prakash CHAUBE（The University of Tokyo） |
| 連名者1 | Takumi SHIMOMURA（The University of Tokyo） |
| 連名者2 | Koichi MAEKAWA（The University of Tokyo） |
| 連名者3 | |
| 連名者4 | |
| 連名者5 | |
| キーワード | |
| 巻 | 15 |
| 号 | 1 |
| 先頭ページ | 1217 |
| 末尾ページ | 1222 |
| 年度 | 1993 |
| 要旨 | INTRODUCTION Prediction of water movement in concrete as a partially saturated media is important both as a natural occurring process as well as for practical applications in engineering design.Most of the deterioration mechanisms occurring in the concrete like carbonation,corrosion of steel bars,possible sulfate attack and many others depend upon the moisture distribution inside the concrete pores.ln fact CEB design guide for durable concrete structures states that“The presence of water or moisture is the single most important factor controlling the various deterioration process apart from mechanical deterioration”.So far the analysis of moisture variation inside concrete in both the time and space domains is done using the well known Fick's second law of diffusion .It is usually assumed that concrete can be treated as a uniform homogenous porous media.However in reality concrete is a non-homogenous porous material and consists of both the aggregate and cement paste pores.In addition some other continuous paths formed due to aggregate to aggregate contact or bleeding might be present.Thus it becomes extremely important to take account of each of these additional components actually existing.ln the past,such effects were modelled by changing the bulk diffusivity of concrete.This approach helped very little to clarify the role and mechanism of individual component of concrete porous system towards the bulk moisture transfer. This study identifies three distinct mediums existing in concrete which Play a role in the overall moisture mass transfer in liquid and gaseous phases. Hereafter these three mediums would be referred to as components of concrete. These components are (a) cement paste pores; (b) aggregate pores (c) aggregate cement paste interface and continuous bleeding paths. Role of each of these components is clarified in the next section. The wetting process is analyzed as a verification target of the multi-component concept. CONCLUSIONS (a) Generally concrete consists of three distinct class of porous components which influence the moisture sorption behavior. (b)These three components can be classified as (1) Cement paste; (2) Channels; (3) Aggregate pores.(c) Low aggregate content induces decreased sorption rate whereas, high aggregate content increases the overall sorption rate under the condition of completely wet face due to channel action. (d) Under humid conditions sorption rate decreases with increasing aggregate content. (e) Sorption behavior of mortar specimens with water Shows a time dependent effect, where the specimen shows a tendency to reseal itself. (f) Analytically observed trends are comparable to the experimental results obtained with alcohol. Finally, from the viewpoint of durability low aggregate contents are desired for concretes subjected to saturated wet face whereas the opposite may be true for humid conditions. |
| PDFファイル名 | 015-01-1207.pdf |