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暴露在大气中的混凝土,经常受碳酸气的侵蚀,混凝土中的水化产物氢氧化钙Ca(OH)_2,与空气中的二氧化碳接触,发生下列碳化反应。 碳化反应也叫混凝土的中性化,因为混凝土水化产生大量的氢氧化钙,此时PH值很高,一般到12～13,但当与空气中的二氧化碳反应之后,使混凝土中的液相PH值降低,向中性发展,即逐渐向PH等于7接近,因PH值降低,使仅仅在高碱性溶液中才稳定的钢筋表面的纯化膜保护层也遭到溶解,钢筋与混凝土的粘结力下降产生裂缝,则空气中的二
Concrete exposed to the atmosphere, often by the erosion of carbon dioxide gas, the hydration product of calcium hydroxide in the concrete Ca (OH) _2, in contact with carbon dioxide in the air, the following carbonation reaction. Carbonation is also called concrete neutralization, because the concrete hydration produces a lot of calcium hydroxide, PH value is very high at this time, generally to 12 to 13, but when reacted with carbon dioxide in the air, the concrete in the liquid phase PH value decreases to neutral development, that is, gradually to PH equal to 7, due to lower PH value, so that only in alkaline solution was stable in the surface of the purified steel membrane protective layer has also been dissolved, steel and concrete viscosity Reduce the force resulting in cracks, then the air in two