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在我国三北地区冬季施工中一般采用硫酸钠、硝酸钠复合外加剂和氯盐、亚硝酸钠复合外加剂。可是亚硝酸钠是致癌物质,掺在房屋混凝土墙板中对人体不利,施工中管理不方便,有中毒和爆炸的危险。并且国内生产不多,每年需从国外进口,价格很贵。氯盐对钢筋有腐蚀作用,特别是最近几年来,北京各建筑公司采用粉剂复合外加剂,虽然掺有亚硝酸钠阻锈,但是由于粉剂不容易全部在搅拌混凝土中同时溶化,氯盐颗粒直接
Sodium sulphate, sodium nitrate compound admixtures, and chloride, sodium nitrite compound admixtures are commonly used in winter construction in the Three North Regions of China. However, sodium nitrite is a carcinogen. It is harmful to the human body when it is mixed in the concrete wall board of a house. It is inconvenient to manage during construction and there is a risk of poisoning and explosion. And there is not much domestic production. It needs to be imported from abroad every year. The price is very expensive. Chloride salt has corrosive effect on reinforcing steel bars. Especially in recent years, Beijing construction companies use powder composite admixtures. Although sodium nitrite is used to prevent rust, powders are not easily dissolved in concrete while stirring. Chloride particles are directly