Analysis of the trend of pH changes of concrete pore solution during the hydration by various analytical methods

Estimating Na+ and K+ concentrations of the pore solution based on ex-situ leaching tests and thermodynamic modeling

“…11 normalizes the sample moisture content based on the thermodynamic data. This effectively means that ESL samples of any moisture content can be used in the present method, or without the need for a separate bulk drying sample recommended by other authors [11,24].…”

“…While there is low variability in the CWE method itself, the free water determination can have a strong influence on results according to studies using Eq. 3 when adjusting concentrations [11,24]. 4b shows the results of a sensitivity analysis of the CWE results indicating how hypothetical changes (+/-5%) of m w, evap.…”

“…The second step of ESL methods generally involves stirring the powdered sample in a solvent, which is most commonly deionized water, and then filtering to obtain a diluted solution for chemical analysis. Several studies on ESL test methods have investigated in numerous factors, including the temperature of the leaching solution [10,16] (Natkunarajah et al recently showed a negligible effect of solution temperature on the results of ESL for concrete [24]), liquid-to-solid ratio [16][17][18][19][20], the duration of the leaching period [19,21,22], and the particle size of the pulverized sample [16,19,21,22]. The list of ex-situ leaching methods resulting from multiple studies includes cold water extraction (CWE) [9,18,19,[21][22][23][24], hot water extraction (HWE) [13,25], and the "espresso" method [11,26].…”

“…Several studies on ESL test methods have investigated in numerous factors, including the temperature of the leaching solution [10,16] (Natkunarajah et al recently showed a negligible effect of solution temperature on the results of ESL for concrete [24]), liquid-to-solid ratio [16][17][18][19][20], the duration of the leaching period [19,21,22], and the particle size of the pulverized sample [16,19,21,22]. The list of ex-situ leaching methods resulting from multiple studies includes cold water extraction (CWE) [9,18,19,[21][22][23][24], hot water extraction (HWE) [13,25], and the "espresso" method [11,26]. These methods have been used to obtain the alkali metal content in g/g of dry sample -a useful metric for AAR studies [9].…”

“…The ESL methods investigated by Plusquellec et al included the CWE method and showed higher alkali contents than PSE [11]. The method of determining of free water content for correcting ESL concentrations has been identified as a potential source of error by multiple authors [11,24].…”