What about the claim that a UHPC essence, local cement and local sand can be used to produce UHPC concrete?

Again and again we read in flyers from UHPC manufacturers that they have a UHPC essence with
which the customer can easily mix a local cement and local sand with this UHPC essence and water and then the customer gets a UHPC concrete. As a rule, this text is very general and does not go into technical details, which has its reasons.

Let's start with the statement:
...locally available cement and sand can be used....

In itself, this statement is not wrong, if we disregard what the customer expects from the quality.
Why?
Well, if we buy a C25 cement, it is impossible to produce a C100 UHPC concrete with a UHPC essence.
If we want to produce a high quality UHPC concrete we need high quality cement, this cannot be changed.
Many users believe that cement from manufacturer A is exactly the same as from manufacturer B if only it says C35.
This is also partly a misconception. Yes, it is true that with both you will get a strength of 35 MPa. But if you look at the anlaysis of the two cements, they could be very different. However, these differences determine the suitability for a UHPC and how it can be processed.
The same applies to aggregates such as sand. Of course I can add local sand but a high quality binder will only be a high quality UHPC if the right sand with the right grading curve is added, otherwise there is a possibility that you will only get a good concrete.

You can of course test the local sand and cement for suitability. Such a test takes one day if the analysis data of the cement and sand are available. We do this cost free for our customers.

 

WPE DK International

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