AI SearchCarbonation and corrosion of reinforcement bar in concrete with different ingredients
Call Number: AIT Thesis no.ST-00-10 Material type:
SeriesSeries: Asian Institute of Technology. Thesis ; no. ST-00-10Publication details: Bangkok : Asian Institute of Technology, 2000Description: 121 leavesSubject(s): Online resources: Dissertation note: Thesis (M. Eng.) - Asian Institute of Technology, 2000 Summary: This study is concerned with the effects of mortar composition on carbonation and corrosion rate. The following condition are selected in this study, 1: 0. 7: 4.5 of cementious: water: sand mix portion, 0%, 15% and 30% fly ash content as the replacement of OPC and 0%, 0.5% and 2% chloride ion by the addition of calcium chloride, 9 types of specimens are constituted according to the designed mix composition. The specimens with steel bar cured in control room are used for the corrosion experiment, and the specimens without steel bar curing water tank are used for the carbonation experiment. In addition, half numbers of specimens with steel bar are subjected to pre-carbonation in order to observe the difference of corrosion between carbonation and non-carbonation. The specimens were exposed at AIT in Thailand for two months and four months. The measurement of carbonation rate, weight loss, surface roughness and visual observation are conducted in this experiment. The results showed that high pressures carbon dioxide dramatically accelerates the carbonation process. Carbonation depth increases with time, it was bigger for the specimens with fly ash than without fly ash, and it increased with the increase of the addition of chloride ion in mortar. The morphology of corroded steel bar exhibited the black corrosion product Fe304.3H20 below the red-brown corrosion products Fe(OH)3, and the scale of corrosion product was founded in relative serious case. Weight loss is bigger for the specimens with fly ash than without fly ash, weight loss increases with the order from 0%, 0.5% to 2%, weight loss increases with exposure period. At 0% and 0.5% chloride ion level, the carbonated specimens have slightly bigger weight loss than non-carbonated ones, at the 2% chloride ion level, the serious corrosion occurs in non-pre-carbonation specimen containing 30% fly ash for two and four months exposure, 15% fly ash for four months exposure. The serious roughening of surface on the corroded steel bar takes place in higher chloride ion concentration, and higher fly ash content. These results show that very severe pitting corrosion occurs under coexistence of high fly ash content and high Cl- concentration.
| Cover image | Item type | Current library | Home library | Collection | Shelving location | Call number | Materials specified | Vol info | URL | Copy number | Status | Notes | Date due | Barcode | Item holds | Item hold queue priority | Course reserves | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
22-AIT Thesis (Replacement)
|
Asian Institute of Technology Library AIT Publications | AIT Thesis no.ST-00-10 (Browse shelf(Opens below)) | 3 | Available | 30050120747125 | |||||||||||||
40-Archives
|
Asian Institute of Technology Library Archives | AIT Thesis no.ST-00-10 (Browse shelf(Opens below)) | 1 | Available | 30050160102082 |
A thesis submitted in partial fulfillment of the requirement for the degree of Master of Engineering, School of Civil Engineering
Thesis (M. Eng.) - Asian Institute of Technology, 2000
This study is concerned with the effects of mortar composition on carbonation and corrosion rate. The following condition are selected in this study, 1: 0. 7: 4.5 of cementious: water: sand mix portion, 0%, 15% and 30% fly ash content as the replacement of OPC and 0%, 0.5% and 2% chloride ion by the addition of calcium chloride, 9 types of specimens are constituted according to the designed mix composition. The specimens with steel bar cured in control room are used for the corrosion experiment, and the specimens without steel bar curing water tank are used for the carbonation experiment. In addition, half numbers of specimens with steel bar are subjected to pre-carbonation in order to observe the difference of corrosion between carbonation and non-carbonation. The specimens were exposed at AIT in Thailand for two months and four months. The measurement of carbonation rate, weight loss, surface roughness and visual observation are conducted in this experiment. The results showed that high pressures carbon dioxide dramatically accelerates the carbonation process. Carbonation depth increases with time, it was bigger for the specimens with fly ash than without fly ash, and it increased with the increase of the addition of chloride ion in mortar. The morphology of corroded steel bar exhibited the black corrosion product Fe304.3H20 below the red-brown corrosion products Fe(OH)3, and the scale of corrosion product was founded in relative serious case. Weight loss is bigger for the specimens with fly ash than without fly ash, weight loss increases with the order from 0%, 0.5% to 2%, weight loss increases with exposure period. At 0% and 0.5% chloride ion level, the carbonated specimens have slightly bigger weight loss than non-carbonated ones, at the 2% chloride ion level, the serious corrosion occurs in non-pre-carbonation specimen containing 30% fly ash for two and four months exposure, 15% fly ash for four months exposure. The serious roughening of surface on the corroded steel bar takes place in higher chloride ion concentration, and higher fly ash content. These results show that very severe pitting corrosion occurs under coexistence of high fly ash content and high Cl- concentration.
There are no comments on this title.