摘要
本文研究了混凝土减水剂的品种、掺量、掺法等对β-半水石膏浆体流动性和石膏硬化体强度的影响。提出了采用P型高效减水剂后掺法,可大幅度提高石膏浆体的流动性。当保持扩展度相同时,采用P型减水剂后掺法,减水剂的用量比同掺法可减少30～50%。石膏浆体属于宾汉姆型流体,后掺高效减水剂,可使石膏浆的屈服剪切应力τ_0和塑性粘度η_p大幅度降低。在水膏此(W/G)不变下,加入减水剂会使石膏硬化体强度略有下降。减水剂不同掺法对石膏浆的作用机理,主要与石膏颗粒的ζ-电位有关,在相同减水剂掺量下,后掺法ζ-电位高于同掺法。利用高效减水剂后掺法,可配制自流平石膏,或使β-半水石膏硬化体强度大幅度提高。
In this paper, the influence of the types, dosages and the adding methods of water-reducing agent(WRA) on flow property of gypsum slurry and strength of set gypsum was studied. The P superplasticizer D-method(delayed adding method) was put forward, which increased the flowability of gypsum pastes by a big margin. Compared with the O-method(original adding method), the D-method reduced the dosages of superplasticizer P up to 30 to 50 percent at a same fluidity of gypsum pastes. The gypsum pastes belong to Bingham body and the D-method for superplasticizer decreased the yield shearing stress τ_o as well as plastic viscosity η_p of gypsum pastes by a big margin. But, the strength of set gypsum slightly decreased with the dosages of WRA at a same W/C ratio. The effect mechanism of the different adding method for superplasticizer is connected with the Zeta-potential of the gypsum particles. At the same dosage of superplasticizer, the Zeta-potential of the gypsum particles in D-method is higher than that in O-method. Adopting tht D-method for suerplasticizer, may make up self-levelling gypsum, or endow the β-semi-hydrated gypsum come up to high strength.
关键词
减水剂
石膏
浆体
强度
流动
β-semi-hydrated gypsum
superplasticizer
O-method(original adding method)
D-method(delayed adding method)
