High performance in tension is probably the most important feature of UHPC, and fibres are responsible for that. They play a major role in ductility, crack control, durability and strength.  As they also represent 60-80% of UHPC cost, it is completely necessary to understand how they work, i.e. tensile response of UHPC. Its knowledge and suitable consideration in design is a must to achieve safe and competitive designs. With this purpose we start a series of posts dealing with the tensile performance of UHPC. I always like to start with a little bit of background. UHPC tensile behaviour can't be fully understood without a previous knowledge of the tensile behaviour of plain concrete. Let's start with it and with some interesting notions you may not know about its response and scale - effect. Warning: It may be kind of tedious to read if you don't have basic knowledge on concrete design !!

One of the main barriers for an increasingly use of UHPC in concrete precast industry is the difficulty of finding a realiable UHPC mixture at an affordable price. If you want to start producing UHPC elements you have two choices: (i) ask specialised companies, commonly cement companies, to provide you with some of their already developed premixes, or (ii) develop one of your own. If you have already asked these specialised companies for a high-quality and reliable UHPC supply and you think what they offer to you is far from making your products competitive (which may be the most likely scenario) and you are afraid you can't do it on your own, in this post you can find some basics you need to follow. Why not give it a try?

A lot of types of UHPC have already been developed worldwide with different mixture compositions, type and amount of fibres, flowability, compressive strength, tensile behaviour, thermal curing, etc. Several standards and recommendations (France, Switzerland) propose their own definition of UHPC. In this post a definition of UHPC is given considering that the most important feature for its classification is not only the compressive strength but algso its ductility and durability properties. Are you interested?