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Influence of ageing of binder systems on the performance of additives

粘结剂体系老化对添加剂性能的影响

基本信息

批准号：
224813219
负责人：
Professor Dr. Johann Plank
金额：
--
依托单位：
Lehrstuhl für Bauchemie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2012
资助国家：
德国
起止时间：
2011-12-31 至 2018-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/224813219?language=en
关键词：
Influence ageing binder systems performance

项目摘要

Chemical aging of the cement takes place during its exposure to atmospheric air. Generally, cement is very hygroscopic and promptly reacts with water and CO2. The aging can take place already during the manufacture and storage of cement. Such aging affects its physical, chemical and mechanical properties such as hydration, stiffening and development of compressive strength. Chemical admixtures such as superplasticizers, water retention agents and accelerators highly depend on the adsorption or composition of the pore solution of the cement to become effective. In this project effectiveness of superplasticizers with aged cement and cement clinker phases was investigated. For this study, methacrylic acid ester and allyl ether-based polycarboxylates (PCEs) were used. Additionally, the influence of aging on the effect of a retarder (sodium gluconate) was examined. It was found that the change of surface charge, resulting from aging, and subsequent agglomeration of the binder particles are the decisive factors for the different behavior of aged cement. These effects are caused by the formation of nanoscale hydrate phases (aging products) which strongly affect adsorption of superplasticizers. In the new project we plan to focus on mortar systems which are particularly rich in admixtures. Another goal is to achieve a deeper understanding of the interaction of admixtures and the influence of aging on the reaction equilibrium in complex binder systems. The results should allow to improve the robustness of mortars under various storage conditions.

水泥在暴露在大气空气中时会发生化学老化。一般来说，水泥具有很强的吸湿性，能迅速与水和二氧化碳发生反应。老化可能已经在水泥的制造和储存过程中发生。这种老化会影响其物理、化学和机械性能，如水化、硬化和抗压强度的发展。化学外加剂，如高效减水剂、保水剂和促进剂，高度依赖于水泥对孔隙溶液的吸附或组成才能发挥作用。在本项目中，研究了水泥熟料相和熟料相组成的高效减水剂的使用效果。在这项研究中，使用了甲基丙烯酸酯和烯丙基醚基聚羧酸酯(PCE)。此外，还考察了老化对缓凝剂(葡萄糖酸钠)效果的影响。研究发现，老化引起的表面电荷变化和粘结剂颗粒的团聚是老化水泥性能不同的决定性因素。这些影响是由纳米水合物相(老化产物)的形成引起的，它强烈地影响高效减水剂的吸附。在新的项目中，我们计划将重点放在砂浆系统上，这种系统含有特别丰富的外加剂。另一个目标是更深入地了解外加剂之间的相互作用以及老化对复杂粘结剂体系反应平衡的影响。研究结果应能提高砂浆在各种储存条件下的耐久性。