Mechanical properties of fly ash aggregate concrete | |
| Author | Pakanai Khaonongbua |
| Call Number | AIT Thesis no.ST-98-03 |
| Subject(s) | Fly ash Aggregates (Building materials) |
| Note | A thesis submitted in partial fulfillment of the requirement for the degree of Master of Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | Fly ash is a by-product from electricity generation. In Thailand, there are approximately 3,000,000 tons/year and increasing rapidly as a result of the electricity demand. Fly ash in this study was obtained from Mae Moh electricity generating plant of EGAT which has pozzolanic property in accordance with ASTM C 618. Some applications of fly ash such as cement replacement, cement manufacture etc. is currently used but there are just a small amount. Artificial coarse aggregate produced from mixing of fly ash with 5-20% of cement and water so-called fly ash aggregate (FAA) for alternative substitution to natural coarse aggregate is one possible effective method for utilizing fly ash in large volume. Fly ash aggregate concrete or F AAC is concrete which uses FAA. Its mechanical properties are investigated here to assure safety of their applications. The peak strain assumption for two phase model application is verified. The assumption is satisfied with confinement effect of mortar on the FAA phase. The relationship between compressive and tensile strength of FAAC is also emphasis on since it is considered to affect to the other criteria such as shear strength and bond strength. This relationship can be obtained from experiments directly and two phase model application. Both yield almost identical relationship to ACI equation for conventional concrete. But some experimental data are below this line as well as some two phase model application get lower strength than calculation from test results. Hence the conservative relationship between compressive and tensile strength of FAAC is proposed to be approximately 80% of ACI equation. Shear strength of FAAC was investigated by third-point loading of beam without shear reinforcement. Effect of compressive strength of FAAC, %reinforcement of longitudinal steel and shear span to effective depth ratio (aid) was observed. These effects were supposed to be the same as those affecting shear strength of conventional concrete and finally ACI equation of shear strength for conventional concrete can be directly applied to use with FAAC. Bond strength of FAAC was investigated by pull-out tests. Effect of compressive and tensile strength of FAAC, shape of FAA, anchorage length, bar diameter and yield strength of bar were observed. Then empirical equation is proposed from the obtained results. Bond strength of F AAC is approximately 70% of ACI equation of bond strength for conventional concrete. Main reasons are considered to be spherical shape and weaker tensile strength of FAA than conventional aggregate. However, the advantages of FAAC are better workability, lighter weight, utilization of waste product (in large volume), substitution to rapidly depletion natural coarse aggregate and environmental treatment both from fly ash and natural coarse aggregate pollution. These satisfy not only engineering but also economical and environmental points of view. |
| 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) | Pichai Nimityongskul ;Somnuk Tangtermsirikul; |
| Examination Committee(s) | Kishi, Toshiharu ;Chotchai Charoenngam; |
| Scholarship Donor(s) | Royal Thai Government; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1998 |