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Hollow Core Slabs > Extruder or Slipformer?
 
 

The solution depends on what the final objective is.

One of the first questions from new producers venturing into Hollowcore production is, “What’s the best technology: Extrusion or Slipforming ? “

The answer depends on what your final objective is, as they both produce hollowcore slabs and there are pros and cons to each technology. The following table summarizes the comparison factors to assist you in the decision making process.

 

Slipforming Extrusion

Notes

Produce HC slabs Both produce HC Slabs.
Produce other precast elements, e.g. inverted T beams, I beams, lintels, etc.   Slipformers offer more versatility.
Lower concrete consumption   Extruders use less concrete than slipformers due to higher compaction, less water and more efficient HC cross section.
Load capacity elements   Extruders offer higher load capacity due to less slab self weight.
Concrete compaction   Extruders operate at higher frequency of vibration. Higher vibration = higher compaction.
Strand bonding (less slippage)   Higher vibration results in better compaction, less strand slippage and less scrap.
Production of lighter elements with higher load capacity   A more efficient slab cross section allows reducing the weight of the slab and a higher load capacity.
Concrete savings   Extruders use less concrete due to reduced cross section area.
Water/Cement ratio   Extruders use a dryer mix (0.3 vs. 0.4+)

Curing time (productivity)

  Extruders allow you to cut the strands as quick as 6 hours due to dryer mix (less water)
Simple to use and operate   Extruder have 1/10th of the moving parts of Slipformer, much simpler to operate.
Use larger aggregates (less expensive concrete)   Extruders provide higher frequency of vibration, allowing the use of larger aggregates. Larger aggregates = more economical and stronger concrete.
Sensibility to Mix Designs   Extruders have a larger range of flexibility to accommodate different mixes, specially those equipped with variable frequency drives and speed.
Maintenance cost   Depends on the technology. In general Extruders have lower maintenance cost due to less moving parts.

Facts

Extruders in general make a more profitable hollow core production, with a lower operating cost.

Slipformers provide the flexibility of producing other precast elements.

What is the best fit for my operations ?

1- Decide your primary precast element first, then make a decision on which technology to use, for example:

  1. If your primary product is hollow core slab, then Extruders is the best fit. Your operating cost will be much lower and higher profits will even justify having a slipformer for other elements, not for hollow core.
  2. If your primary precast element is not hollow core, then the Slipformer is the answer, as it will also allow you to produce hollow core slabs and the higher cost of production will have a lower impact in your bottom line.

Hollow Core is a more advanced technology and more efficient than other precast elements for flooring. Hollow Core is widely used in North America, Europe, Middle East and Asia, with an impressive expansion into Central and South America. Even though there are some Hollow Core plants in Africa, there are still other methods that are more common in this region.

Hollow Core Extruders or Slipformers? It is certainly an interesting topic…give us a call to discuss more, we offer a free consulting service to assist you in your Hollow Core needs and are able to provide you with comparisons for both operations based in industry facts and statistics.

 

 
 
Disclaimer: This document has been prepared by Ultra-Span Technologies Inc. and revised by producers of hollow core slabs that operate both technologies, Extruders and Slipformers.  Even though we have tried to be unbiased, we recommend the reader to consult other sources. We strongly recommend the production of hollow core slabs by extrusion process.