To make a phenolphthalein solution for carbonation depth detection, this is generally done by first putting 1 gram of phenolphthalein into 100 ml of 95% ethanol and shaking until completely dissolved. The specific steps are as follows:
Weigh phenolphthalein first: If you want to make 1% phenolphthalein reagent, you need 1 gram of phenolphthalein.
Re-dissolve phenolphthalein: pour the weighed phenolphthalein into 95% ethanol, shake it gently or use a special vibrator to help let the phenolphthalein completely dissolve in ethanol until the solution becomes clear.
Storage: Generally, put the prepared phenolphthalein reagent in a drop bottle. If the alcohol is volatilized, you can add a little more alcohol to maintain the effectiveness of the reagent.
Measuring the carbonization depth: When measuring the carbonization depth of concrete, the phenolphthalein reagent is dropped on the concrete break. Phenolphthalein will turn red when it encounters an alkaline environment, but the carbonization place will not change. By looking at the boundary between the discolored and non-discolored areas, the carbonization depth can be measured with tools such as vernier calipers.
There are a few more points to note:
The concentration of ethanol used is generally 95%, so that phenolphthalein can be dissolved.
Shake well before use to ensure that the reagent is uniform.
When measuring the carbonization depth, the concrete surface should be clean, free of dust and debris, otherwise the accuracy of the results will be affected.
The phenolphthalein reagent should be added at the edge of the fracture to facilitate the demarcation of color changes.
When reading the carbonization depth value, it is necessary to measure it several times and then average it, so that the data is more reliable.
In this way, the carbonization depth of concrete can be accurately detected. Pay attention to safety during the experiment, especially when using flammable ethanol, ventilate and keep away from fire.