RDC Website
  • Home
  • About RDC
  • Engineering projects
  • Concrete Technologies
  • R&D Actions
  • UHPC for People
UHPC For People- RDC Blog
UHPC for People: The RDC's Blog
SUBSCRIBE
UHPC mixing
Juan Ángel López
Monday, 30 October 2017 / Published in Learning UHPC

Having your own UHPC

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?

First thing you have to know is that despite sometimes we talk about UHPC as if it were kind of almighty material whose development is only for the few, UHPC is just concrete. A special one. That’s true. One that requires a special care. We can’t deny that. One in which a mistake may lead to a substantial loss of money. Don’t forget it anytime, but don’t despair.

UHPC is a special type of concrete you can reliably produce if your are already producing concrete

As a conventional concrete, UHPC is made of cement, aggregates, superplasticiser and water. In case of UHPC, maximum aggregate size is commonly lower than 2 mm. UHPC is a mortar !! Most typical aggregate used is quartz sand. Regarding cement, good news! UHPC has been made with a wide variety of cements. However, we strongly recommend low heat hydration rate cements. The use of one or another cement depends on (i) local cement availability ,(ii) its compatibility with superplasticiser, (iii) your needs of higher or lower initial strengths, and, sometimes, (iv) the colour desired.

Unlike conventional concrete, UHPC contains pozzolanic additions, such as silica fume, fly ash, gound granulated blast-furnace slag (GGBS), metakaolin, nanosililca, fluid catalytic cracking residue, etc.; and fibres, commonly short straight steel fibres. We suggest using silica fume as a compromised solution between prices, strength and stability of the mixture. Regarding fibres, we strongly advice you to look for the best price in the market. Fibres represent between 60-80% of the overall price of UHPC mixture. That’s quite a lot !! If you are dealing with short straight steel fibres (most typical ones), only start negociating below 2.5 €/kg. Don’t be ripped-off !!

If you want a cost-effective UHPC, make your own !! Use available local materials, whenever is possible. If you have problems to get it, look for the support of specialised consulting companies on UHPC. There is no doubth that it is going to be both quicker and cheaper.

Is it require a huge investment in equipment to manufacture UHPC in your own precast factory?

NO !!

You don’t need special or high technology equipment to produce it. You just need a mixer and a more or less advanced system to weight material with little deviation.

It is fine if you can weight all components with a margin of error of 2%. In case of water, you need to guarantee a margin of error below 1%. Accomplishing that is not a tragedy in most of existing precast factories. Don’t never forget that water is the most important thing you need to control. A low deviation in the water content may lead to a high deviation in strength, stability and flowability of the mixture. So, follow these two advices:

  • Margin of error in the added water must be below 1%
  • If you can’t control moisture content of your materials preciseley, buy them dry

Regarding the mixer, there is only one thing you need to know! UHPC can be made in all existing mixers. A man of science would tell you that an intensive mixer is required (i) to a better dispersion of fine and ultra-fine particles, (ii) to achieve higher strength by reducing water content; (iii) to reduce mixing times. Even though that is absolutely true, it is also true that we can achieve all of that in a common industrial planetary mixer.

UHPC can be made in a common industrial planetary mixer, taking between 15 and 20 minutes

Following video shows the process of manufacturing 15 litres UHPC in laboratory conditions using a very low intense mixer. It is quite impressive to see all changes in the manufacturing process of UHPC.

During the first 40 seconds the dry mixing of cement, sand and additions takes place.

At 40 seconds all the water required is added. However, for the next 4 minutes UHPC remains with the same aspect!! And it would never change if not for the superplasticiser.

Superplasticiser is introduced at minute 4, and it takes 20 minutes to react with cement particles to achieve flowability required. The higher the mixing energy, the less this process takes. Here lies the importance of an intesive energy mixer.

Steel fibres are added at 25 minutes, once mixture is flowable. If you are to produce UHPC, it is a must that you keep always the following sentence in your mind: “fibres must be added once UHPC is flowable to reduce the amount of mixing energy required or to produce a higher volume of UHPC with a given mixing energy”. Believe me, your mixer will hate you forever if you put fibres at the beginning of the mixing process.

 

Are you ready to have your own UHPC and start playing with it?

 

 

What you can read next

UHPC beam complete failure RDC
Tensile behaviour of UHPC (III). Into FRC tensile response
Durability lightness and aesthetics in UHPC applications
The reasons for using UHPC in different sectors
Tensile behaviour of UHPC (II). Softening behaviour and scale-effect in plain concrete

1 Comment to “ Having your own UHPC”

  1. Dr J D Bapat says :
    December 2, 2017 at 5:26 pm

    Very good article!

UHPC for people posts

  • Reshealience project prototype made by RDC and PREFFOR

    Interesting newsletters about advanced concretes

  • Durability lightness and aesthetics in UHPC applications

    The reasons for using UHPC in different sectors

  • Cost of UHPC

  • The European Project SMARTINCS offers 8 full-time Early Stage Researcher (ESR) positions

  • Formex® floating platforms as a useful infrastructure for the development of the Blue Growth potential

  • New project (AVI): UHPFRC with new fiber technologies and its application in ultralight slabs

  • UHPC beam complete failure RDC

    Tensile behaviour of UHPC (III). Into FRC tensile response

  • H2020 | RIA | Towards the Ultra High Durability concept – ReSHEALience Project

  • Fibres in UHPC

    What we have to know about fibres in UHPC

  • Tensile behaviour of UHPC (II). Softening behaviour and scale-effect in plain concrete

  • Multi-microcracking in UHPC: real case application

  • RDC CHRISTMAS

    Merry Christmas and happy New Year ! – RDC

  • Tensile behaviour of UHPC (I). Digging into plain concrete tensile response

  • ReSHEALience project

    H2020 | RIA | Presenting Project ReSHEALience

  • The roofing of the Montpellier – South of France TGV Station

  • What is UHPC? – Part 2: Requirements

  • UHPC: a living reality

  • H2020 | SME Instrument. SELMUS Project

  • Innovation

    RDC – The Art of Innovation

  • The beginnings of RDC

  • SF particle in UHPC

    What is UHPC? – Part 1: Birth of UHPC

  • UHPC for People word cloud

    UHPC for people- The RDC Blog

SEARCH

Categories

Into our everyday life Learning UHPC Market UHPC applications News RDC: The Art of Innovation RDC News ReSHEAlience - H2020 SELMUS - H2020 UHPC Costs UHPC Worldwide Innovation
5 days agoRT @Preffor_Formex: Bateas #Formex subvencionables con fondos del #FEMP destinados a la #acuicultura https://t.co/6X7E1YqBYv
5 days agoRT @Preffor_Formex: Las #BateasFormex son ya una realidad en #Galicia. Te lo cuentan en este vídeo sus protagonistas, los bateeiros das Ría…
32 days agoRT @Preffor_Formex: Consulta online el desarrollo del proyecto en el que participamos junto con @rdconcretes @OpenMode_EU: Módulos para cul…
47 days ago¿Te lo perdiste? Ahora puedes ver la grabación completa del webinar dedicado al #UHPC. Muchas gracias por la invit… https://t.co/vBXp2TkEpd
60 days agoRT @Preffor_Formex: Presentamos la línea #formexwine con nuestro #fudre #fudreelypso. Una nueva etapa dispuestos a aprender de los maravill…
Follow @rdconcretes

We're ready to optimize your products using advanced concretes

Contact us if you sense we can assist you to develop, redesign, calculate and assist for the production of precast concrete elements

CALL US NOW
logo RDC footer page

Research & Development Concretes S.L.

RDC is an engineering company expert in advanced concrete solutions. The company supports concrete producers in the development, design, redesign, calculation or production of precast elements, reducing their costs, adding more value and optimizing their products.

Flag_of_EuropeThis company has received funding from the European Union´s Horizon H2020 research and innovation programme under grant agreement Nº 760824, 738777, 860006 and from the European Maritime and Fisheries Fund OpenMode-863562

  • Cookie Policy
  • Privacy Policy

NEWSLETTER

To receive news from RDC in your inbox mail, subscribe to our list

Subscribe form

FOLLOW US

CONTACT INFO

rdconcrete@rdconcrete.com

+34 630 314 389
+34 669 085 020

Calle Conde Altea, 52 pta 3
46005 Valencia (España)

TOP
Be aware that this site uses cookies. AcceptRead more