30 years of fundamental difference between UHPC and concrete

This photo is more than 30 years old. It is from the first flyer I used to sell UHPC. The photo was meant to explain to our customers what the general difference between concrete and UHPC is, because almost all of our customers at that time had no idea what the difference between concrete and UHPC is. At the time, I found this photo comparison brilliantly simple and clear.

Today, after 30 years, our team still has the feeling that many write and talk about UHPC but really do not recognise the basic difference. On the contrary, people today try to dilute and obfuscate the difference between concrete and UHPC. For these professionals, everything and nothing is concrete and UHPC. There are very few professionals who can explain the difference in simple and logical language. However, the architect, the structural engineer or the construction company must know the difference in order to be able to use both materials optimally.
For this reason we have decided to bring out this very old photo and to try again to explain the difference between concrete and UHPC and hope that some interested people out there will follow us, to whom we would like to thank already now.

The idea behind this photo was to produce two test cylinders and subject them to a pressure test. The main point was not to find out which material has the higher compressive strength, that was clear from the beginning.
No, we wanted to show and compare the fracture surface. This fracture surface shows the difference so simply and clearly.
At the beginning we mixed a standard cement binder and a UHPC binder and added the same grading curve and material quality to aggregates, filled them into test cylinders and waited 28 days. After 28 days, the concrete and UHPC cylinders were demoulded and pressed in a press until they broke. The result of this fracture can be seen in this photo.

The left cylinder is the standard concrete cylinder and the right cylinder is the UHPC cylinder.
Looking at the left cylinder, the fracture surface is clearly in the binder, the gravel aggregate is not broken. The weak point in this case is the cement binder.
If we look at the right cylinder, the fracture has gone through the gravel aggregate and the UHPC binder simultaneously and evenly. There is no weak point here. The UHPC binder is just as hard and resistant as the aggregate and the adhesion between aggregate and binder is extremely high.

This photo comparison and the resulting result shows that there are two fundamentally different binder systems, the concrete binder and the UHPC binder, whereas the UHPC binder is superior to the concrete binder by several times. This is how it was then, how it is now and how it will be in the future.

WPE DK International

Phone: 0049 176 601 73146
E-mail: ber@wpe-dk.dk
Homepage: www.wpe-dk.com