Characterization of self-consolidating concrete (SCC) rheological properties

混凝土技术的新发展导致了土木工程应用中使用的混凝土类型以及性能要求的变化。新水泥、新矿物和化学外加剂的使用导致了高性能混凝土(HPC)和自固结混凝土(SCC)的发展。高性能混凝土和自密实混凝土具有许多优点，如高强度、高弹性模量、较少的渗漏、较少的蠕变和较高的耐久性。例如，SCC是一种高度流动的混凝土，可以很容易地扩散并在自身重量下自我固结，而不会出现离析。这些混凝土技术也被强加了更严格的性能要求，主要是耐久性，以确保寿命。目前，还没有制定标准的测试方法来确保新浇筑混凝土的质量，并确保其符合耐久性和其他结构要求。 新拌混凝土的质量可以通过其均质性以及搅拌、运输、压实和完工的简易性来衡量。流变学是研究物质随时间变形和流动的科学，它提供了控制混凝土质量的材料特性。目前，混凝土流变学的定性特征仍然是工作性、流动性、密实度、稳定性、精细性、可泵性和稠度，而没有适当地参考基本的性能测量。为了克服这些不足，提出了一种基本的和定量的方法来充分描述新拌SCC混凝土的流动。 利用混合料组成来预测混凝土的流变性是一种新的方法。其他重要的未来成果将是开发一种整体方法，以设计具有所需流变性、力学性能和耐久性的最佳混凝土混合料比例。这些发展将提高混凝土的经济可行性，减少废物和节约自然资源，所有这些都将导致可持续的混凝土基础设施。

New developments in concrete technology have resulted in changes in the types of concrete used in civil engineering applications as well as the performance requirements. Use of new cements and new mineral and chemical admixtures have led to the development of high performance concrete (HPC) and self-consolidating concrete (SCC). HPC and SCC present numerous advantages such as high strength, high elastic modulus, less bleeding, less creep, and high durability. For example, SCC is a highly flowable concrete that can spread easily and self consolidate under its own weight without segregation. Stricter performance requirements, mainly durability, have also been imposed on these concrete technologies to ensure longevity. At present, standard test methods have not been developed to ensure quality of the fresh concrete and its compliance with durability and other structural requirements. Quality of fresh concrete can be characterized by its homogeneity, and the ease with which it can be mixed, transported, compacted and finished. Rheology, which is defined as the science of deformation and flow of matter with time, provides the material properties for controlling the quality of concrete. At present, concrete rheology continues to be qualitatively characterized by terms such as workability, flowability, compactability, stability, finishability, pumpability, and consistency, without a proper reference to fundamental measurements of properties. To overcome these inadequacies, a fundamental and quantitative approach is proposed to adequately describe the flow of fresh SCC concrete. Predicting concrete rheological properties using the mixture composition is a novel approach. Other significant future outcomes will be the development of a holistic approach for designing the optimum concrete mixture proportions with the desired rheological properties, mechanical properties and durability. These developments will enhance the economic viability of concrete, will reduce waste and conserve natural resources, all leading to sustainable concrete infrastructure.