Calcium complexation and cluster formation as principal modes of action of polymers used as superplasticizer in cement systems
Calcium complexation and cluster formation as principal modes of action of polymers used as superplasticizer in cement systems
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DOI：
10.1016/j.cemconres.2015.01.016
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发表时间：
2015-07-01
影响因子：
11.4
通讯作者：
Ludwig, Horst-Michael
中科院分区：
文献类型：
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作者：
Sowoidnich, Thomas;Rachowski, Tim;Ludwig, Horst-Michael
超塑化剂被添加到新混凝土中以改善和易性。超塑化剂与水泥在水化过程中的相互作用尚未完全了解。它是调查，如果测量的影响主要是有关的聚合物结构，因此必须考虑在discussions.By滴定实验和利用钙选择性电极的定量络合离子在水溶液中的研究。通过测定总有机碳（TOC）分析了聚合物在水泥和硅酸三钙上的吸附。最后，水溶液进行了研究，通过分析超离心。聚合物对钙离子的络合是由其官能团引起的吸引力的结果。因此，在溶液中和表面上都观察到络合作用（吸附）。除了离子-聚合物复合物之外，还证明了形成有机聚合物和无机晶体的较大聚集体（簇）。因此，超增塑剂发挥三种不同的主要作用模式。(C)2015爱思唯尔有限公司版权所有。
Superplasticizers are added to fresh concretes in order to improve workability. The interaction of superplasticizers with cement during hydration is not fully understood. It is investigated if the measured effects are principally related to the polymer structure and must therefore be considered in discussions.By means of titration experiments and utilizing a calcium selective electrode the quantification of complexed ions in aqueous solution is investigated. Adsorption of polymers both on cement and tricalcium silicate is analyzed by measuring the total organic carbon (TOC). Finally, the aqueous solution is investigated by analytical ultracentrifugation. (AUC).Complexation of calcium ions by polymers is the result of attractive forces evoked by their functional groups. Thereby, complexation is observed both in solution and on surfaces (adsorption). Besides ion-polymer complexes it is demonstrated that also larger aggregates (clusters) of organic polymers and inorganic crystals are formed. Thus, superplasticizers exert three different principal modes of action. (C) 2015 Elsevier Ltd. All rights reserved.