盐类早强剂和防冻剂在北方地区应用很广，阻锈剂则在全国有着较广泛的应用。工程中由于对它们的使用不当造成的混凝土早期开裂较为严重。本项目主要研究盐类外加剂（包括常用无机盐和部分有机盐）及其与高效减水剂、引气剂复掺时，对混凝土早期孔结构、气孔结构、孔隙中溶液成分、浓度、表面张力等的影响规律及作用机理，研究它们对混凝土内部相对湿度和早期收缩与早期开裂的影响规律与作用机理，以及混凝土早期收缩与早期开裂的关系，研究混凝土早期抗裂性与早期弹性模量、早期强度及其增长率的关系。提出掺加盐类外加剂混凝土的开裂模型和避免出现早期开裂的常用盐类外加剂的掺量临界值（单掺、复掺），为盐类外加剂在实际工程中的合理使用和提高我国混凝土材料自身的抗裂性、耐久性提供理论支撑和技术支持。

Salts are widely used as high-early strength admixtures or anti-freeze admixtures into concrete in most northern regions with cold climate, while corrosion inhibitors are used around the whole country. The early cracking caused by improper use of these salts is a serious problem in many concrete structures. In this research, the effect and principle of salts, which are inorganic salts or organic salts used separately or used with superplasticizer and air entraining agents, on the pore structure at early age and the air voids structure of concrete will be investigated as well as the composition, concentration and surface tension of salt solution in the pores. And then, the effect and principle of these salts on the internal relative humidity within concrete, early shrinkage and cracking at early age and the relation of two will be studied. In addition, the relations of crack resistance of concrete with salts and early elastic modulus, early strength and its growth rate will be found. Furthermore, a cracking model of concrete containing salts will be established, and the critical dosage of salts to avoid early cracking in concrete will be given. The results and conclusions would provide theoretical basis and technique guidance for the proper usage of salts in the concrete structure and improving the crack resistance and the durability of concrete.