Characterization of DURA-preblended UHPC for bridge construction according to the CHBDC standards

超高性能混凝土（UHPC）是一种新兴的非常有弹性的纤维增强胶凝材料，可用于缓解加拿大桥梁和其他暴露在恶劣环境中的基础设施所面临的耐久性和有限的使用寿命问题。由于密实的填充物，UHPC具有很少连接的毛细孔，因此水和氯化物的进入和扩散速度比传统混凝土慢得多；具有高长径比的分布钢纤维延迟裂纹局部化的发生，使其具有出色的拉伸应变能力而不损失强度。在加拿大市场上，可获得的超高压混凝土产品很少，而加拿大公路桥梁设计规范委员会正致力于建立用于桥梁建设的超高压混凝土材料质量控制程序-被称为附件S（A23.1）的文件草案即将实施。Facca是一家加拿大公司，生产一种独特的材料DURA-UHPC，完全使用在加拿大开采的原材料生产。工业合作伙伴在桥梁建设中使用DURA-UHPC所面临的挑战是，通过在实验室中进行机械和恶劣暴露条件的物理建模，证明该材料能够经受住时间的考验，并满足桥梁建设100年长使用寿命的目标。但测试程序在灵敏度和与UHPC真实现场性能的相关性方面尚未完全了解，因此这是一个正在进行的研究领域。一些必需的测试很难进行，或者需要特殊的专业知识和测试设施。由于在规范标准中正式引入UHPC是非常新的，因此很难找到拥有所需资源的组织来进行和评估规定的机械和耐久性测试的整个集合的准确性和相关性。PI针对的研究挑战是验证测试，并在必要时通过DURA-UHPC校准，对即将在规范中引入的UHPC材料的测试程序草案进行微调。这项研究将满足双方的目标，并将为优化材料和测试方案提供见解。

Ultra High Performance Concrete (UHPC) is an emerging class of very resilient fiber reinforced cementitious materials that can be used to mitigate the durability and limited-service life issues faced by Canadian Bridges and other infrastructure exposed to aggressive environments. Due to dense packing, UHPC has very few connected capillary pores so that ingress and diffusion of water and chlorides is much slower than in conventional concrete; distributed steel fibers with a high aspect ratio delay the occurrence of crack localization enabling spectacular tensile strain capacity without strength loss. In the Canadian Market there are only few available UHPC products whereas the Canadian Highway Bridge Design Code Committees are engaged in establishing procedures for quality control of UHPC materials for implementation in bridge construction- the draft document, known as Annex S(A23.1) is about to be enforced. Facca is a Canadian Company that produces a unique material, DURA-UHPC, produced entirely with raw materials quarried in Canada. The challenge faced by the industrial partner in order to use DURA-UHPC in bridge construction is to demonstrate through physical modeling of mechanical and aggressive exposure conditions in the lab, that the material can stand the test of time and meet the objectives of 100-year long service life of bridge construction. But the testing procedures are not fully understood in terms of sensitivity and relevance to the true field performance of UHPC, so this is a field of ongoing research. Some of the required tests are challenging to conduct or require special expertise and testing facilities. As the official introduction of UHPC in the Code Standard is very new, it is challenging to find organizations that have the resources needed to conduct and assess the accuracy and relevance of the entire collection of prescribed mechanical and durability tests. The research challenge targeted by the PI is to proof test and if necessary, fine-tune, through calibration with DURA-UHPC, the draft testing procedures for UHPC materials that are about to be introduced in the Code. The research will meet the objectives of both partners, and will provide insights for optimizing the material and testing protocols.