Occurrence of intercalation of PCE superplasticizers in calcium aluminate cement under actual application conditions, as evidenced by SAXS analysis
Occurrence of intercalation of PCE superplasticizers in calcium aluminate cement under actual application conditions, as evidenced by SAXS analysis
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DOI：
10.1016/j.cemconres.2013.09.002
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发表时间：
2013-12
影响因子：
11.4
通讯作者：
S. Ng;E. Metwalli;P. Müller‐Buschbaum;J. Plank
中科院分区：
文献类型：
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作者：
S. Ng;E. Metwalli;P. Müller‐Buschbaum;J. Plank
小角x射线散射（SAXS）分析证实了聚羧酸盐（PCE）高效减水剂在理想和实际应用条件下在铝酸钙水泥（CAC）早期水化过程中的插层作用。通过XRD、TEM、SEM和元素分析对CaAl-PCE-LDHs进行了表征，发现PCE样品具有多分散性，层间距离（d值）在5 ~ 24 nm之间。pce的插层能力取决于其接枝密度和阴离子性，而与分子量无关。当使用高阴离子pce时，回收了大量的纳米晶、胶体插层物，而当使用低阴离子pce具有高接枝密度时，检测到的插层物很少。因此，与OPC相反，较少的阴离子pce可以更好地分散CAC，因为通过插层浪费的量很少，而由于有机矿物相的丰富形成，更多的阴离子pce需要更高的剂量。最后，对水泥中PCE嵌入物的可靠分析提出了建议。
Intercalation of polycarboxylate (PCE) superplasticizers in calcium aluminate cement (CAC) during early hydration under both idealized and actual application conditions was confirmed by small-angle X-ray scattering (SAXS) analysis. The CaAl-PCE-LDHs were characterized by XRD, TEM, SEM and elemental analysis, and exhibited interlayer distances (d-values) ranging from 5 to 24 nm, owed to the polydispersity of the PCE samples. Intercalating ability of the PCEs was dependent on their grafting density and anionicity, but was independent of their molecular weights. When highly anionic PCEs were utilized, significant amounts of nanocrystalline, colloidal intercalates were recovered, while few intercalates were detected when less anionic PCEs possessing high graft density were employed. Thus, contrary to OPC, less anionic PCEs disperse CAC better as little amount is wasted via intercalation, whereas higher dosages are required for more anionic PCEs, owed to abundant formation of organo-mineral phases. Finally, recommendations for reliable analysis of PCE intercalates in cement are given.