A Study on Repairing cement-based materials attacked by the alkali-aggregate reaction using the electrochemical rehabilitation method

Autor: Ming Fung He, 何明峰
Rok vydání: 2008
Druh dokumentu: 學位論文 ; thesis
Popis: 96
Alkali-aggregate reaction affects the durability of RC structures. Three alkali-aggregate reactions are known as alkali-silica aggregate reaction, alkali-carbonate aggregate reaction and alkali-silicate aggregate reaction. In this study, the electrochemical rehabilitation method for repairing concrete suffered from the alkali-silica aggregate reaction is studied. The elongations of mortar bars are measured to see the effects of electrochemical rehabilitation process and the compressive strength are performed to monitor the change in mechanical properties. Two rehabilitation processes were considered: (1) using electrochemical method to force lithium ions migrate into concrete and remove the potassium and sodium ions (one-stage rehabilitation process); (2) performing the above-mentioned process then performing the electrochemical deposition method to repair internal defects which may possibly exist during the alkali-silica aggregate reaction (two-stage rehabilitation process). After performing these rehabilitation processes, ASTM C1260 is conducted once more to see resistance of the alkali-silica aggregate reaction of the rehabilitated specimens. Results showed that using 2N Li(OH)2 as the electrolyte the compressive strength and the elongation values showed better performance than 1N Li(OH)2. In addition, using 2N Li(OH)2 as the electrolyte the resistance to the second-time alkali-silica aggregate reaction is higher. The two stage rehabilitation process show a better compressive strength recovery than the one stage rehabilitation process no matter a cracked or uncracked specimen is considered. For cracked specimens, calcium deposit can enhance the resistance of chloride ions, corrosion and carbonation
Databáze: Networked Digital Library of Theses & Dissertations
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