Predictive tools for improving and controlling the quality and durability of concrete

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。新型水泥和新型矿物和化学外加剂的使用导致高性能混凝土（HPC）和自固结混凝土（SCC）的发展。HPC和SCC具有高强度、高弹性模量、少出血、少蠕变和高耐久性等优点。例如，SCC是一种高流动性的混凝土，它可以很容易地扩散，并且在自身重量下自固结而不会离析。更严格的性能要求，主要是耐久性，也被强加在这些混凝土上，以确保寿命。目前，还没有标准的测试方法来保证新拌混凝土的质量及其符合耐久性和其他结构要求。新鲜混凝土的质量可以以其均匀性和易于混合、运输、压实和完成为特征。流变学是研究物质随时间的变形和流动的科学，它为控制混凝土的质量提供了材料特性。目前，混凝土流变学的定性特征仍然是可加工性、流动性、压实性、稳定性、可完成性、可泵送性和一致性等术语，而没有适当参考基本的性能测量。为了克服这些不足，提出了一种基本的定量方法来充分描述新混凝土的流动。此外，通过建立流变特性、混凝土加工和硬化混凝土特性之间的联系，可以开发出一个整体的混凝土配合比设计，以控制新混凝土的质量，优化不同工艺的混凝土成分，并提高其耐久性。这些发展将提高混凝土的经济可行性，减少浪费和保护自然资源，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 to ensure longevity.  At present, standard test methods have not been developed to ensure quality of the fresh concrete and its compliance with the 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 concrete.  Moreover, by proposing to establish links between rheological properties, concrete processing and properties of hardened concrete, a holistic concrete mix design can be developed for controlling the quality of fresh concrete, optimising concrete composition for different processes and improving its durability.  These developments will enhance the economic viability of concrete, will reduce waste and conserve natural resources, all leading to sustainable concrete infrastructure.