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混凝土中掺入化学外加剂,已成为冬季施工的重要方法之一,为缺乏蒸汽或电热能源的露天分散工程的冬施创造了有利条件。目前混凝土外加剂已由单一剂发展到复合剂,其中以NaNO_2复合剂在负温混凝土中最为常用。NaNO_2和早强剂复合使用,其电解溶液能降低水的冰点,使水泥水化在负温下继续进行。复合组分中,NaNO_2主要起抗冻作用,早强剂Na_2SO_4、NaCl或磺化焦油主要起负温下的早强和增强作用。
The incorporation of chemical admixtures in concrete has become one of the important methods for winter construction, creating favorable conditions for the winter application of open-air decentralized projects lacking steam or electric heat energy. At present, the concrete admixture has developed from a single agent to a compound agent, and NaNO 2 compound agent is most commonly used in negative temperature concrete. When NaNO2 is used in combination with early strength agent, the electrolytic solution can reduce the freezing point of water, and the hydration of cement can continue at negative temperature. Among the composite components, NaNO 2 mainly acts as a frost-proofing agent, and the early strength agents Na 2 SO 4 , NaCl or sulphonated tar mainly act as early strength and reinforcement under negative temperature.