A method is proposed which comprises placing a portland cement concrete or mortar sample with a harmless solution, based on a variety of anthocyanins, which acts as an indicator yielding a color which is visibly different in zones where an alkaline reserve exists (pH ~ 12) (green) from that observed in carbonated areas (pH ≤ 9) (blue). We firstly experimented with various solutions containing anthocyanins extracted from flowers and fruits, after which food colors commercialized in the European Union were utilized seeking to prepare a reproducible method. The tested products are three food colors coming from grape, black carrot and red cabbage obtained by means of extraction and later dehydrated by spray dying. The solutions which seem most appropriate to us contain 2.5% of color dissolved in a liquid where alcohol and water are mixed at a 70/30 ratio.

中文翻译：

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在硅酸盐水泥混凝土中使用花青素溶液来确定碳化深度

提出了一种方法，该方法包括将波特兰水泥混凝土或砂浆样品与基于各种花青素的无害溶液一起放置，作为指示剂，在存在碱性储备 (pH ~ 12) 的区域产生明显不同的颜色（绿色）来自在碳酸化区域（pH ≤ 9）（蓝色）中观察到的。我们首先试验了各种含有从花卉和水果中提取的花青素的溶液，然后利用在欧盟商业化的食用色素来寻求可重现的方法。被测产品为葡萄、黑胡萝卜和红甘蓝三种食用色素，经萃取后经喷雾染色脱水。对我们来说最合适的解决方案包含 2。