Concrete carbonation depth measurement reagent and preparation and application methods thereof

Abstract

The invention discloses a concrete carbonation depth measurement reagent and preparation and application methods thereof. The concrete carbonation depth measurement reagent is prepared from thymol blue, phenolphthalein, alizarin yellow R, sodium hydroxide, absolute ethyl alcohol and distilled water. In the components, the thymol blue, the phenolphthalein and the alizarin yellow R and alkaline substances with different pH values in carbonated concrete are correspondingly subjected to color reactions, and thus color development relations with obvious distinctions are obtained for the concrete with different degrees of carbonization, and the effect that the concrete carbonation depth is measured accurately is achieved. Color overlapping caused by different reagents is taken into account by adopting a color superposition principle; the sodium hydroxide, the absolute ethyl alcohol and the distilled water are taken as lytic agents of the thymol blue, the phenolphthalein and the alizarin yellow R; the protective agent is good in stability, is non-toxic and environment-friendly, is easy to manufacture and high in accuracy, can be widely used for depth measurement of various carbonated concrete, and rapidly measuring of the concrete carbonation depth is facilitated.

Description

technical field [0001] The invention relates to the technical field of concrete carbonation depth measurement, in particular to a concrete carbonation depth measurement reagent and a preparation and application method thereof. Background technique [0002] Concrete carbonation is a phenomenon in which cement hydration products react with infiltrated carbon dioxide to form carbonates, which causes the destruction of the chemical balance of the system and leads to the deterioration of the performance of the concrete system. Concrete is widely used in the current civil engineering field due to its advantages of wide source of materials, high cost performance and strong plasticity. However, concrete structures often face serious carbonation problems, which lead to a decrease in the alkalinity of the concrete system and damage to the passivation film on the surface of the steel bar, thereby reducing the durability and service life of the concrete structure. Therefore, concrete c...

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Problems solved by technology

[0003] Up to now, the method used for measuring carbonation depth mainly comprises following four kinds of methods: 1) phenolphthalein indicator method; Its test object is: measure pH>10 area; Its test mechanism is: spray 1% phenolphthalein solution on the split surface of concrete, Measure the length of the discoloration area; advantages: convenient and quick to obtain approximate carbonization depth; disadvantages: the carbonization surface is not obvious enough, and there is a certain error in the measured value

2) Thermal analysis method; its test object is: determination of calcium hydroxide and calcium carbonate content; its test mechanism is: heat the sample to 900°C, and calculate the content of calcium hydroxide and calcium carbonate according to the heat content change of calcium hydroxide and calcium carbonate before and after heating; Advantages: Partial carbonation area can be evaluated; Disadvantages: Only the carbonization of calcium hydroxide can be judged, but the carbonization of calcium silicate hydrate cannot be judged

3) X-ray phase analysis method; the test object is to determine the mineral types before and after carbonization; the test mechanism is: carry out X-ray diffraction on the sample, compare the standard diffraction pattern, and judge the structure and name of the mineral before and after carbonization; advantages: Partially carbonized areas can be evaluated; Disadvantages: It is difficult to identify and analyze amorphous substances, and the accuracy of quantitative analysis is not high

4) Infrared spectroscopy; its test object is: determination of carbon dioxide and calcium carbonate content; its test mechanism is: use infrared spectroscopy to measure the C=O bond in carbon dioxide and the C-O bond in calcium carbonate to determine the amount of both; advantages: High characteristic, not affected by the physical state of the test sample; Disadvantage: high sample quality requirements

[0004] To sum up, the accuracy of the phenolphthalein measurement method is too low, and the latter three methods are not convenient to operate and the cost is relatively high. At present, most of the experimenters use 1% phenolphthalein reagent to spray on the carbonation depth of concrete when measuring the carbonation depth. The measurement results and disadvantages are as follows figure 1 shown

[0005] from figure 1 It can be seen that there is a large discrepancy between the carbonation depth of concrete measured by phenolphthalein and the actual carbonation depth of concrete, and the pH value that affects the corrosion rate of steel bars in concrete is about 9-12, so the test results of phenolphthalein do not have sufficient practical significance

[0006] From the existing concrete carbonation depth measurement reagents and their use effects, it is difficult to guarantee the accuracy of the test results by using concrete carbonation depth measurement reagents with only a single performance

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