Identify the reactivity of aggregates in Taiwan and using electrochemical techniques to mitigate expansion due to alkali-aggregate reaction in concrete

• Main Authors: Chih-Chien Liu, 劉志堅
• Other Authors: Lee Chau
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/56464623222077581572

博士 === 國立中央大學 === 土木工程研究所 === 91 === Abstract The scope of this research is essentially six fold: 1) evaluate the alkali reactivity of aggregates in Taiwan using ASTM C289, C227, C1260, and C1293 tests; 2) research the reaction of lithium ion in concrete; 3) study the effect of using LiOH as expansion inhibitor on alkali-aggregate reaction in different environments; 4) study the transport of ions in concrete due to the action of 1D electrical field as the driving force; 5) study the transport of ions in concrete due to the action of 2D electrical field as the driving force; 6) purpose the strategy of preventing AAR damage in concrete using electrochemical technique Test results showed that ASTM C289 test is suitable to accept aggregates but not to reject them. C1260 test is too severe for many aggregates, but C1260 can be used as a quality control method. The amount of expansion could be inhibited when the Li/Na molar ratio was greater than 0.74 in humid environments. For the environments containing alkalis, the effective Li/Na molar ratio to inhibit expansion was increased. To shorten the treatment time and increase the treatment effect, this research by means of electrochemical technique with 1D and 2D electrical fields drove lithium ions into and removed sodium ions from mortar bars. The performance of preventing AAR can observe the increasing lithium and sodium concentrations in the cathode solution, which can be divided into three steps. Results showed that ions concentration, proportioning of concrete mixtures, curing time, and electrical fields design are affected the treatment effect.