Assessment of simple methods of determining the free chloride ion content of cement paste

Influence of cementitious binder on chloride removal under electrochemical treatment in concrete

“…Thus, the chlorides chemically bound in the cement matrix have no corrosiveness, even if electrochemical treatment could not arrest and extract these chlorides in concrete. Chlorides could be alternatively bound within C-S-H gel and adsorbed on the surface of silicate hydrates with no chemical conversion [12,13]. Thus, chlorides physically adsorbed/bound could be decomposed into free by electric charge.…”

AFREM test procedures concerning chlorides in concrete: Extraction and titration methods

“…It is to be noted that the drilling, grinding and crushing of concrete must be performed carefully to prevent heating and resulting calcium chloroaluminate degradation. It has been shown [5] that chloride removal is the same if the concrete grain size is lower than 0.600 mm. For AFREM procedures, the recommended grain size is 0.315 ram, which is usually obtained in most laboratories.…”

“…However, the value of this ratio is not of very great importance [5] as far as the extraction effectiveness is concerned. This value has only a practical importance: it facilitates the handling and operations (solid dispersion, magnetic agitation).…”

“…test conditions (contact duration, temperature) varied [3][4][5]. To select the test procedures, the AFREM group took into account the origin of chlorides present in concrete and their interactions with hardened cement.…”

Semi-quantitative Prediction of the Corrosion Risk of Steel in Concrete Using XRD Analysis

“…Prior to sampling by crushing and grinding, the specimens were dried in an oven at 104°C for 24 h. Then, ground dust sample was sieved through a 300 μm mesh, and 1.0-3.0 g of the dust sample was placed in a beaker with 50 ml of still water at 50°C. The suspension sample was stirred for 5 min and stood for 30 min to extract water-soluble chloride, as being mostly equivalent to free chloride (Arya et al 1987). Then, the sample was filtered to measure the concentration of free chloride ions, using potentiometric titration with silver nitrate.…”