Modeling physical and chemical effects of fly ash on hydration-heat of concrete | |
| Author | Mom Mony |
| Call Number | AIT Thesis no. ST-99-12 |
| Subject(s) | Fly ash Hydration Fly ash Hydration |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering. |
| Publisher | Asian Institute of Technology |
| Abstract | This study is aimed to extend the applicability of a multi-component hydration heat model (COMH3) for blended cement developed by Kishi et al.(1996) for arbitrary types of fly ash by implementing micro-filler effect of fly ash into the model so that it can be used in wider range to predict temperature rise in concrete structures. Fly ash particles, which are prone to be inert at the early age, are reported to enhance the hydration of cement. It is possible that fly ash particles act as nucleation sites for Ca(OH)z and C-S-H formation resulting in a higher rate of cement hydration for all the cement minerals. So in the proposed model, the physical effect of fly ash accelerates the referential heat rate of all four main components of cement was adopted as the ratio of surface area of fly ash to cement. In addition to enhanced cement hydration, fly ash by itself has the ability to react typically with Ca(OH)2 acts as an activator released from the cement hydration to form C-S-H hydrates. Due to the shortage of Ca(OH)2 the hydration stagnates even if the reaction of fly ash still continues in lower rate. Hence the concentration of Ca(OH)2 in solution plays a crucial role. In the modified model this phenomenon was interpreted by consumption ratio of Ca(OH)z by fly ash based on the chemical composition of fly ash as a C/S molar ratio of C-SH gel and its variation during the heat hydration process. By incorporating the physical and chemical effect of fly ash, the current model can be used for any types of fly ash with overcoming fly ash replacement up to 60 percentage by weight. The proposed model was verified both adiabatic temperature rise and quasi-adiabatic temperature rise in comparison with tested data from previous researchers. Almost of all cases show a good agreement between the tested values and the predicted one. Accuracy of the proposed model was found in engineering point of view. |
| Year | 1999 |
| Type | Thesis |
| School | School of Engineering and Technology |
| 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.;Kishi, Toshiharu.; |
| Examination Committee(s) | Nii, Kazuyoshi;Pichai Nimityongskul;Somnuk Tangtermsirikul; |
| Scholarship Donor(s) | Prof. D.Severino Dianich, Italy; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1999 |