| 種別 | paper |
| 主題 | New Aspects Affecting the Mutual Relation between Strength and Permeability of Concrete |
| 副題 | |
| 筆頭著者 | Mohamed ANWAR（Constructions Research Institute） |
| 連名者1 | Hosny SOGHAIR（Assiut University） |
| 連名者2 | Megahed AHMED（Assiut University） |
| 連名者3 | Manabu FUJII（Kyoto University） |
| 連名者4 | |
| 連名者5 | |
| キーワード | |
| 巻 | 15 |
| 号 | 1 |
| 先頭ページ | 1229 |
| 末尾ページ | 1234 |
| 年度 | 1993 |
| 要旨 | INTRODUCTION It is essential that concrete should withstand the conditions for which it has been designed without deterioration, over a period of years. The permeability of concrete is influenced by the environment in which the concrete is exposed or internal factors within the concrete itself. The external factors can be physical, chemical or mechanical: they may be due to weathering, occurrence of extreme temperature, abrasion, electrolytic action, and attack by natural and industrial liquids and gases. The internal factors are alkali-aggregate reaction, volume change due to differences in thermal properties of aggregates and cement paste. The permeability of concrete largely determines the vulnerability of concrete to external agencies, so that in order to be durable concrete, the concrete must be relatively impervious. The higher permeability of mortar or concrete in actual structures is due to the following reasons: 1. Formation of micro-cracks due to long-term drying shrinkage.2.Rupture of interface bond between aggregate and paste due to unequal thermal stresses.3.Cracks generated through construction stresses.4.Due to volume changes caused in the concrete on account of various minor reasons.5.Existence of entrapped air due to insufficient compaction. In this paper the light is focused on the relation between permeability and strength of concrete by using local materials and using the water penetration depth method (input method) to measure the permeability of concrete. Also, the effect of Changing the mix proportions during mixing and casting on permeability and strength of concrete is highlighted. CONCLUSIONS On the basis of experimental work, this paper comprises the test results of 47 mixes for strength and permeability with different parameters. The following are the main findings: 1.Test results support the fact that the permeability of concrete is a function in its quality defined by its strength. 2.For practical consideration, a minimum permeability and hence high strength for concrete can be achieved by: a) Increasing the cement content and curing period. b) Proper adjusting the richness, S/G ratio and W/C ratio. c) Increasing the N.M.S.of gravel up to a certain limit. d) Good mixing and compaction leading to high graded concrete. e) Using certain and specific type with proper dose of admixtures. 3.Test results showed that strength admixture is more beneficial and effective rather than permeability admixture from both permeability and strength improvement point of view. So the preliminary tests should be carried out on any admixtures before using it. 4.The arbitrary acceptable limit of coefficient of permeability is 1.5×10-1l(m/s) for concrete which can be achieved by adding admixtures or changing the concrete mix proportions. |
| PDFファイル名 | 015-01-1209.pdf |