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、新型矿物掺合料和化学掺合料的使用导致了高性能混凝土和自密实混凝土的发展。 高性能混凝土和自密实混凝土具有强度高、弹性模量高、泌水少、蠕变小、耐久性高等优点。 例如，SCC是一种高度流动性的混凝土，可以很容易地分散，并在其自身重量下自固结而不分离。 更高的性能要求，主要是耐久性，也被强加在这些混凝土上，以确保寿命。 目前，尚未制定标准测试方法来确保新拌混凝土的质量及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匀性和易于混合、运输、压实和完工来表征。流变学是研究物质随时间的变形和流动的科学，它提供了控制混凝土质量的材料特性。目前，混凝土流变性仍然是定性的特征，如和易性，流动性，可乳化性，稳定性，可修整性，可泵性和一致性，没有适当的参考基本测量性能。为了克服这些不足之处，提出了一个基本的和定量的方法来充分描述流动的新鲜混凝土。 此外，通过建议建立流变性能，混凝土加工和硬化混凝土性能之间的联系，可以开发整体混凝土配合比设计，以控制新拌混凝土的质量，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，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.