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通过水化热、热分析等手段研究了两种具有相同侧链长度,但桥接基团不同(酯基、醚键)的聚羧酸系超塑化剂(PCs)对铝酸三钙(C3A)-石膏水化行为的影响。结果表明:当石膏与C3A的摩尔比为0.3时,PCs的加入能促进硫酸根的消耗,加快C3A的溶解,有利于单硫型硫铝酸盐(AFm)的沉淀,但对水榴石(C3AH6)的生长具有抑制作用。PCs的化学结构与其吸附能力息息相关,侧链桥接基团为酯基时,PCs在C3A-石膏体系中的吸附量较大,对C3AH6的生长抑制作用更强。由于PCs与硫酸根离子在C3A颗粒表面发生竞争吸附,PCs部分占据颗粒表面的溶解点,进而释放出额外的自由硫酸根离子,这是PCs促进硫酸根消耗并加速AFm相形成的原因。
Two kinds of polycarboxylate superplasticizers (PCs) with the same side chain length but different bridging groups (ester groups and ether bonds) were studied for hydration and thermal analysis. Effect of gypsum hydration behavior. The results show that when the mole ratio of gypsum to C3A is 0.3, the addition of PCs can promote the consumption of sulfate and accelerate the dissolution of C3A, which is favorable for the precipitation of monosulfite sulphoaluminate (AFm) C3AH6) has an inhibitory effect on the growth. The chemical structure of PCs is closely related to their adsorption capacity. When the side chain bridging groups are ester groups, the PCs adsorbed more in the C3A-gypsum system and have a greater inhibitory effect on the growth of C3AH6. Due to the competitive adsorption of PCs and sulfate ions on the surface of C3A particles, the PCs partially occupy the solution surface at the particle surface, releasing additional free sulfate ions, which is why PCs promote sulfate consumption and accelerate AFm phase formation.