Multi-phase modelling of electrochemical rehabilitation for ASR and chloride affected concrete composites

A study on the durability of structural concrete incorporating electric steelmaking slags

The electrically conductive carbon nanotube (CNT)/cement composites for accelerated curing and thermal cracking reduction

Dimensional stability of electric arc furnace slag in civil engineering applications

Alkali-silica reaction (ASR) in the alkali-activated cement (AAC) system: A state-of-the-art review

The Accelerated Lithium Migration Technique (ALMT) is an electrochemical method to remove Na + and K + from concrete, and simultaneously drive Li + into concrete to inhibit alkali-silica reaction (ASR). This study investigates the relationship between the applied voltage and the migration behavior of cations related to ASR. The results show that after the completion of Na + and K + removal, migration of Li + begins to enter a steady state. With the increase in applied voltage, the removal rate and removable amount of alkalis increases, the required time of alkalis removal and the time for Li + to pass through the specimen decreases, and the migration coefficients of Li + increase. Furthermore, the above migration parameters of cations have positive linear relationships with the average current density. After the ALMT process, the average Li/(Na + K) molar ratio of the specimen is sufficiently large to mitigate ASR problems.

/pdf/behavior-of-cations-in-mortar-under-accelerated-lithium-8qp7ugg08u.pdf

Behavior of cations in mortar under accelerated lithium migration technique controlled by a constant voltage

/pdf/effective-asr-inhibiting-length-and-applied-electrical-field-1u3wc86m50.pdf

Effective asr inhibiting length and applied electrical field under accelerated lithium migration technique

This study discussed firstly the mortar bar mix design proportion suitable for detecting the expansion behavior of furnace slag in cement matrix. Mortar bars were produced according to this mix proportion by replacing 1?9% of natural fine aggregate by highly expansive BOF (Basic Oxygen Furnace) slag. The mortar bar expansion amount was detected referring to the autoclaving procedure of ASTM C151 test. The effect of a small addition of highly expansive slag on the volume stability of cement matrix material was analyzed. The results showed that the mortar bar mix proportion suitable for detecting the expansion behavior of furnace slag in cement matrix was aggregate-cement volume ratio 3. The aggregate gradation met ASTM C227, and the standard flow water consumption was used. Replacing 1% of natural fine aggregate by BOF slag also caused apparent expansion of mortar bar in the autoclave expansion test. It was proved that a small amount of highly expansive slag in the cement matrix material has adverse effect on the volume stability. In addition, the furnace slag with expanding property must be stabilized before it is used as cement matrix aggregate.

Effect of a small addition of highly expansive slag on volume stability of cement matrix material

This research focuses on the feasibility of employing the mortar bar autoclave test (MBAT) and the concrete prism autoclave test (CPAT) for the evaluation of alkali-silica reactivity in 22 aggregates. ASTM C289, C227, C1293, AFNOR P 18-588, and JIS A 1804 tests were also conducted for purposes of comparison. Expansions of 0.05% for the MBAT, and the 0.04% CPAT method are suggested as criteria for the differentiation of non-reactive aggregate. Without underestimation, more than 90% of the results obtained from the MBAT were consistent with the ASTM tests. Each result obtained by the CPAT was similar to the ASTM tests. The ASTM C289, MBAT, and CPAT methods are recommended as effective tools for identifying non-reactive aggregate in routine or screening tests.

Study of autoclave methods for evaluating the alkali-silica reactivity of aggregates

In this study, an Accelerated Lithium Migration Technique (ALMT) was applied to simultaneously drive alkali out and lithium into concrete as a remedy for alkali-silica reaction (ASR) problem. The mortar specimens used in the experiments contained 2.0% Na2Oeq. Constant current denities were applied during the ALMT testing process. The anolyte and catholyte solutions consisted of LiOH．H2O and Ca(OH)2, respectively. The results show that there are a well correlated linear relationship between the applied current density and the steady flux and migration coefficient of the Li+. During the process of ionic migration, K+ was first removed completely from the specimen, followed by Na+, after which the Li+ flux remained steady. The system resistance initially decreased, and then increased gradually. The time corresponding to when the Li+ concentration in the cathode/Li+ in the source cell was equal to 0.1% indicates the time-span needed for Li+ to penetrate throughout the specimen. Furthermore, the accumulated charge carried by the cations and the accumulated charge applied during testing showed a similar in all test cases.

Wei Chien Wang

Papers

Behavior of cations in mortar under accelerated lithium migration technique controlled by a constant voltage

Effective asr inhibiting length and applied electrical field under accelerated lithium migration technique

Effect of a small addition of highly expansive slag on volume stability of cement matrix material

Study of autoclave methods for evaluating the alkali-silica reactivity of aggregates

Migration of Cations in Mortar under an Electrical Field Controlled by a Constant Current Density