高性能混凝土外加剂的选择原则

SELECTIVE PRINCIPLE OF HIGH PERFORMANCE CONCRETE'S ADIMIXTURE

高性能混凝土外加剂要满足在低水胶比下提高混凝土流动性的要求 ,即减水率要大(一般在20%以上) ,混凝土坍落度经时变化要小 ,故应选择能增加水泥粒子表面电位、降低拌和水的表面张力、能使水泥粒子分散好的外加剂。同时还应考虑外加剂与水泥、掺合料的适应性 ,以及冬季施工中用于高性能混凝土的防冻剂。

The high performance concrete' s adimixture should fulfill the following requirements ,namely:1,low rate of cement consumption ,2,high fluidity of concrete i.e.,3,the water raduction ratio should be the largen the better(generally over 20%)and 4,the periodical fluctuation of concrete's slump shluld be the smaller the better.Therefore,the adimixture should possess the properties as follows:1,increasing of cement-particle's surface electro-potential ,2,decreasing of mixing water's surface tension and 3,dispersing of cement-particles to perfection .Simultaneously the adoptability of adimixture cement and other mixtures should be well considered.Besides,the anti-freeze of high performance concrete for winter construction should be duly deliberated.