| Author | Liu, Liwen |
| Call Number | AIT Thesis no. ST-98-24 |
| Subject(s) | Concrete--Expansion and contraction
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of
Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | Expansive concrete is a kind of concrete which hardens accompanied by expansion. The aim of using expansive agent is to produce shrinkage-compensate and self-stress concrete. The use of expansive concrete in RC structures result in a significant reduction in crack formation and width of cracks caused by drying shrinkage compared to the use of ordinary concrete, so it is an effective method for improving the durability of structure. In addition, expansive agents also bring other properties for concrete, such as time dependent deformability and re-expansion after cracking under wet conditions. Because re-expansion after cracking can improve the capability of resistance to corrosion of concrete and prolong the lift span of concrete, thus the re-expansion of expansive concrete significantly increases durability of concrete. This thesis studied deformability of expansive reinforced concrete after cracking in terms of hydration process. From microstructure of concrete, it is known that the internal structure of concrete is looser after cracking. The ettringite is provided with space to grow, so re-expansion takes place. The capacity of re-expansion is determined by early degree of hydration. Several factors that influence hydration and expansion were investigated, such as water/cement ratio, reinforcement ratio, and the age of the specimen. Because shrinkage generally takes place throughout the concrete life span, the release of shrinkage and deformation with time were also studied. Results indicated that water/cement ratio, the method of curing at an early stage and reinforcement ratio are three fundamental factors determining capacity of re-expansion. However water cement ratio is the key factor to influence the capability of re-expansion. The lower the water/cement ratio, the more the re-expansion after cracking. All of these results mean that lower water/cement ratio expansive concrete can enhance the property of concrete structure in aspects of both structure and durability. |
| Year | 1998 |
| Type | Thesis |
| School | School of Civil Engineering |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Kishi, Toshiharu; |
| Examination Committee(s) | Pichai Nimityongskul;Pennung Warnitchai; |
| Scholarship Donor(s) | Government of Japan; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1998 |