Filling the Void

Supplying construction sites with ready-mix concrete can be challenging: long transport distances, hold-ups en route or elevated ambient temperatures make it essential to draw up detailed contingency measures. A much simpler alternative is to use self-filling concrete compound (SFCC) that can be prepared directly on site. Getting the flow characteristics right is key to this approach – and can be achieved with polymer modification.

The mono-grain has the perfect initial grain size for the production of SFCC.

The application of SFCC on a construction site requires only two components: one is the coarse aggregate, i.e. gravel or grit, which can be supplied locally, and the other is the modified dry-mix mortar compound. First, the aggregate is filled into the prepared bed, which in principle can be of any size, and then the dry-mix mortar is combined with water and pumped in to fill up the voids.

The highly fluid mixture seeps into every crack, filling the gaps between all the stones and forming a strong bond with them. Setting time and strength can be adjusted to the local climate, technical requirements and to the timeframe of the project.

Flow Characteristics are Key

The flow characteristics of SFCC are key. The liquid mixture must not flow too slowly or too quickly through the aggregate. If it stops flowing too soon or if air bubbles form, the stability of the entire concrete component will be at risk.

Polymer modification with ETONIS® dispersible powder from WACKER results in a unique rheology that cannot be achieved with conventional super-plasticizers.

See How it Works

Our video illustrates the performance capability of SFCC: the SFCC is poured into a V-shaped acrylic glass tube filled with crushed mono-grain, with which it forms a strong bond.

Advantages of SFCC at a Glance:

  • Convenient just-in-time solution: the compound is there where you need it, when you need it.
  • Not subject to the vagaries of the weather or other, adverse conditions.
  • Setting time and strength can be adjusted to the local climate, the technical requirements and to the timeframe of the project.
  • System can be formulated to set very quickly – even in less than one hour if desired.
  • SFCC is virtually shrinkage-free thanks to the particle-on-particle structure.
  • The strong bond that forms minimizes susceptibility to cracking.
  • Simple logistics: gravel or grit can be supplied locally or is already available on site e.g. recycling materials.
  • Less waste – none of the unforeseen supply problems that arise with ready-mix concrete.

Read More in Our Technical Article

Author: Dipl.-Ing. Klaus Bonin

Published in: Drymix Mortar Yearbook 2019

Want to Know More about Concrete Additives?

WACKER polymeric binders, such as ETONIS®, are ideal concrete additives. For more information, visit the WACKER product portal.

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