Investigating the Rheological Behavior of Low Water-to-Cement Concretes Admixed With Superplasticizers and Co-Dispersants and the Underlying Dispersion Mechanism

以非常低的w/c比（< 0.30）配制的混凝土越来越受欢迎。然而，涂抹者经常报告说，对于那些蠕变而不是流动的混凝土，在工作现场浇筑时表现出低速流动。这种流变行为是非常不希望的安置过程。该项目的目的是确定低w/c比混凝土的粘性和蠕动流动行为的主要原因，并提供潜在的解决方案来克服这种不利的流变特性。关于这一点，PCE高效减水剂的特定结构基序将被确定，有利于高速流动。此外，非离子共分散剂将作为流动增强剂进行测试，并通过使用不同的实验技术（例如动态光散射，临界胶束浓度等）更详细地研究这种新型分散的工作机制。该项目的总体目标是显著加深对低w/c体系中分散机制的了解，并将获得的吸附层厚度、HLB值和单个PCE分子结构基序的数据与屈服应力、塑性粘度和流动速度等关键流变参数联系起来。

Concretes formulated at very low w/c ratios (< 0.30) have become increasingly popular. However, applicators often report a honey-like consistency for those concretes which creep rather than flow and exhibit a low speed of flow when poured at the job site. Such rheological behavior is highly undesirable for the placement process.The aim of the project is to ascertain the main causes for the stickiness and creeping flow behavior of concretes of low w/c ratios and to provide potential solutions to overcome such unfavorable rheological properties. Regarding this, specific structural motifs for PCE superplasticizers will be identified which favor a high speed of flow. Additionally, non-ionic co-dispersants will be tested as flow enhancers and the working mechanism underlying this new type of dispersion will be investigated in more detail by using different experimental techniques (e.g. dynamic light scattering, critical micelle concentration etc.).The overall goal of this project is to significantly deepen the knowledge on the dispersion mechanisms occurring specifically in low w/c systems, and to interconnect the data obtained for the adsorbed layer thickness, HLB values and structural motifs of individual PCE molecules with key rheological parameters such as yield stress, plastic viscosity and flow speed.