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

点击翻译按钮获取中文摘要

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.