UHPC From Research to Standardization: European Approaches

Abstract

Abstract In Europe, different approaches to standardize ultra-high-performance concrete (UHPC) materials, and the design of structures made from it, are pursued based on different philosophies and market situations. The first standard available was published in France. It primarily deals with material models and design procedures for steel-fiber-reinforced UHPC. Material-related aspects are not considered. This is because, as a rule, industrially prefabricated dry premixed concretes with consistent material properties are used. Thus, the European Standard for concrete materials, EN 206 [EN 206, 2012-03, 2012, “Concrete—Specification, Performance, Production and Conformity,” German Version, German Standardization Body, Beuth Verlag, Berlin], is of minor relevance. The philosophy in other countries, like in Germany, is to make UHPC a commonly available material based on individual, application-oriented compositions, as far as possible being manufactured in precast or ready-mix plants from appropriate regionally available raw materials. Thus, the application of UHPC will be favorably supported by considering UHPC to be part of the harmonized European concrete materials and design standards, EN 206, covering the material aspects, and EN 1992-1-1 [EN 1992-1-1: 2011-01, 2011, “Eurocode 2:2 Design of Concrete Structures. Part 1-1: General Rules and Rules for Buildings,” German Version, German Standardization Body, Beuth Verlag, Berlin] (Eurocode 2) covering the design. This approach requires advice on how to evaluate the appropriate raw materials, to prepare adequate mixtures, and to define technically based rules and requirements covering both mechanical, as well as durability aspects, e.g., by defining strength- and durability-related classes, as for ordinary and high-performance concrete. The requirements have to be related to reliable testing procedures. It has been proven by several research projects in Germany that European standard testing procedures may principally be adopted but have to be modified in some points, e.g., with respect to the specific fresh concrete properties, the specimen preparation, tests to evaluate the fiber efficiency, etc. These topics are under discussion in a UHPC-related committee of the German Standardization Body (DIN) drafting a standard-like technical guideline covering all three aspects, namely, materials, design, and testing. Another technical guideline on UHPC is elaborated by Fédération Internationale du Béton (FIB). The approach is “in between,” meaning that some material aspects are covered as far as their relevance for the structural design. The focus lies on the design covering different design procedures for fiber, as well as for conventionally reinforced structural elements.