Hydration heat model for concrete blended with limestone powder, and for high blast furnace slag content concrete | |
| Author | Dorjpalamyn, Saruul |
| Call Number | AIT Thesis no. ST-98-13 |
| Subject(s) | Hydration--Mathematical models Concrete--Research |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | Multi-component hydration heat model (COMH3) for Portland cement developed by Kishi et al. is practiced in this paper. The model describes hydration reaction of cement in terms of reaction of its individual components. This study is to expand the applicability of the model for concrete blended with limestone powder and for high blast furnace slag content concrete. Several semi-adiabatic temperature rise tests were conducted in a middle scale specimen in order to verify modeling of those powders. It is well known that the inert fines, such as limestone powder, promote an acceleration of cement hydration. Fines provide depositing sites for hydration products to precipitate. In this study it was found that the accelerating effect initiates from the stage of hydration when ions start to dissolve into the solution and supply of nuclei believed to stimulate formation of hydration products, especially C-S-H gel. The accelerating effect introduced in diffusion-controlled stage as well. Reduction of the outer product of cement grain due to its deposition onto filler makes water diffusion to the unhydrated core of the grain easier. So, the effect of limestone powder is introduced into the model by accelerating the referential heat rates of cement silicate constituents (C3S, C2S) at all stages of hydration process. Hydration of slag proceeds only in the presence of activator, such as Ca(OH)2 or other suitable alkali. Consumption of calcium hydroxide by unit weight of slag is stable when sufficient amount of the alkali is supplied. But due to shortage of activator, especially in high slag content concrete the active hydration of slag stagnates, but reaction still continues though in lower rate. So, in this study, the moderate reaction of slag in high replacements is expressed through the changing consumption ratio of calcium hydroxide by slag reaction according to concentration of the alkali in the solution. The accelerating effect of limestone powder as well as the function of consumption ratio of Ca(OH) 2 by slag were implemented in COMH3. Computational results showed good correlation with the thread of quasi-adiabatic test. |
| 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;Wijeyewickrema, Anil C.; |
| Scholarship Donor(s) | Government of Japan;ADB; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1998 |