The Systematization of the Elemental Technology of Materials for the Control of Concrete Fluidity

为了发展自密实混凝土、高强混凝土和高耐久混凝土，有必要用梳型高效减水剂控制混凝土的流动性。本研究对混凝土流动度控制材料的以下基本技术进行了系统化研究，指出控制铝酸盐相早期水化是控制混凝土流动度的必要措施。由于C_3A周围形成的凝胶中含有大量的SO_4~(2-)，C_3A的早期水化被延缓。在C_3A-CaSO_4体系中加入梳状高效减水剂，由于抑制了向凝胶中提供SO_4~(2-)，加速了C_3A的早期水化。增加游离CaO含量可以延缓C3A-石膏体系中C3A的早期水化。提出了提高CaO掺量对控制梳型高效减水剂水泥早期水化的作用。由于无机电解质对梳型高效减水剂悬浮液流动性的影响，接枝长度较短的聚合物即使吸附位置减少，也更容易被吸附。用苯乙烯或烯丙基磺酸盐取代甲氧基聚乙烯后，接枝链间距延长，共聚物组成发生变化。掺入缓冷高炉矿渣粉(SBFS)后，由于C3A的早期水化延迟，砂浆的流动性保持率低于不掺SBFS的砂浆。此外，还研究了飞灰中未烧碳、集料粘土矿物或外加剂对梳型高效减水剂悬浮液流动性的影响。

For the development of self compacting concrete, high strength concrete and high durable concrete, it is necessary to control the fluidity of concrete with comb-type superplasticizers. This study discusses the systematization of the following elemental technologies of materials for the control of concrete fluidity.It is necessary to control the early hydration of aluminate phase in order to control the fluidity. The early hydration of C_3A is retarded, as there is much content of SO_4^<2-> in the gel formed around C_3A. Adding of comb-type superplasticizers in C_3A-calcium sulfates systems accelerates the early hydration of C_3A, because the supply of SO_4^<2-> to gel is inhibited. Increasing free-CaO contents retards the early hydration of C_3A in C_3A-gypsum system. It is proposed that the increase of CaO contents would be effective for controlling the early hydration of cement with comb-type superplasticizers. For the influence of inorganic electrolytes on the fluidity of suspension with comb-type superplasticizers, the polymer having a shorter grafted length is adsorbed more easily even though the number of adsorption sites is decreased. The interval between grafted chains were prolonged, with changing composition of copolymer when methoxypolyethylene is replaced by styrene or allyl sulfonates. By adding of slowly cooled blast furnace slag powder (SBFS), the fluidity retention of mortar is smaller than that of mortar without SBFS due to the retardation of the early hydration of C_3A. In addition, the influence of unburned carbon in fly ash and clay mineral of aggregates or additives on the fluidity of suspension with comb-type superplasticizers have been also investigated.