Influence of superplasticizers on the structure-property relationship of fresh cement pastes analyzed by novel rheological combined techniques

我们的目标是开发不同的新策略和概念，以便在分子过程的基础上描述新拌混凝土的变形和流动过程，同时也考虑到介观过程。其中一个重点是以流变学为主要技术的分析和渗透新拌混凝土的相关加工操作，并将其与提供分子或结构信息的辅助方法(介电、核磁共振、SAXS和IR)相结合。流变学在很大程度上受到所研究材料的形态和分子性质的影响，例如新拌混凝土。流变学可以建立分子结构和力学性能之间相互作用的结果，流变学和互补方法的结合允许获得关于分子动力学、时间结构和剪切相关现象的独特信息。流变学和介电特性的组合可以提供有关局部分子松弛动力学(如水)和宏观对机械力的响应之间关系的详细信息。在砂浆或混凝土中，水泥浆体在加工和沉降过程中受到不同的剪应力，例如将材料浇注到模具或框架中。因此，在不同的时间内，将以不同的速率进行流变学测量。流变学-核磁共振：在水泥浆体的水化过程中，为水泥基材料提供足够的水分是重要的，以确保其力学和耐久性能的适当发展。水作为一种纯液体或通过携带腐蚀性物质参与混凝土的形成和退化。水化水泥基材料的1H-核磁共振弛豫时间研究与流变学相结合，可以同时研究新拌混凝土混合料的核磁共振分子动力学和相应的力学响应。流变学：该方法将在拟议的水泥水化化学研究项目中实施。在拟议的项目中，将通过红外光谱手段监测新鲜水泥样品的水化情况。为了更好地了解新建筑材料悬浮液的流变行为，将利用流变学-IR技术研究单个颗粒或颗粒与载体液体相互作用的机理。为了首先实现这一点，我们需要开发一种新的装置，能够同时测量流变光谱和红外光谱，并提高灵敏度，将机械非线性与红外光谱直接相关。这种新的全球独一无二的组合方法将能够调查和分析活性(水化)颗粒的相互作用，包括量化形态、化学、温度、时间等影响的能力，从而建立新混凝土材料中颗粒相互作用的更完整的模型。

Our goal is to develop different novel strategies and concepts in order to describe the deformation and flow processes of fresh concrete on the basis of molecular processes, taking also into account mesoscopic processes. One important point is the analysis and penetration of the relevant processing operation of fresh concrete using rheology as the main technique and combined it in-situ with complementary methods (dielectric, NMR, SAXS and IR) offering molecular or structural information. Rheology is highly influenced by the morphology and the molecular properties of the investigated materials, e.g. fresh concrete. Rheology can establish the result of the interplay between molecular structure and mechanical properties, the combination of rheology with complementary methods allows to gain unique information about molecular dynamic, structure of time and shear dependent phenomena.Rheo-dielectric: the combination of rheological and dielectric properties can give detailed information about the relation between local molecular relaxation dynamics e.g. water and the macroscopic response to mechanical forces. In mortar or concrete, the cement paste is submitted to different shear stresses during processing and settling, e.g. the pouring of the material into a mould or framework. Therefore, rheological measurements will be carried at different rates for different durations.Rheo-NMR: Providing adequate moisture content in cement-based materials is important during hydration of the cement paste to ensure proper development of their mechanical and durability properties. Water is involved in the formation and deterioration of concrete either as a pure liquid or by carrying aggressive species. 1H-NMR relaxation time studies of hydrating cement based materials combined with rheology can be used to study simultaneously the molecular dynamics via NMR and the corresponding mechanical response for fresh concrete mixtures.Rheo-IR: This method will be implemented during the proposed project to study the chemistry of cement hydration. In the proposed project the hydration of fresh cement samples will be monitored by means of infrared spectroscopy. The mechanisms of the interaction between individual particles or between particles and the carrier liquid will be investigated with Rheo-IR technique for a better understanding of the rheological behavior of fresh building material suspension. To accomplish first this, we need to develop a new setup that is able to simultaneously measure rheological and infrared spectra with an improved sensitivity to directly correlate mechanical nonlinearity with IR spectroscopy. The new and worldwide unique combined methods will enable the investigation and analysis of the interaction of reactive (hydrating) particles, including the ability to quantify the effects of morphology, chemistry, temperature, time, etc. leading to a more complete model of particle interactions in fresh concrete materials.