ICF Help & Advice

Our insulated concrete formwork help & advice centre has been created as a reference and information hub for designing and building ICF structures in general, and Polarwall in particular.

ICF Construction

Pouring the Concrete by Boom Pump

Concrete is placed in several ways. The most common method is to use a concrete boom pump.  The cost of the boom pump is determined by the size of the pump and the length of its reach.  Take care to order a pump that when extended can reach the far end of the structure comfortably.  The nominal size of the pump stated in metres and refers to its vertical height.  The base of the pump line is a few metres above ground. Therefore a 32 metre concrete pump will typically only have an extended reach of around 29 metres horizontally.

The boom pump needs space around it to so that it can extend its legs. The legs stabilise the concrete pump. These are needed when the boom arm is extended. 

Ideally the delivery pipe should be of a 3 inch diameter, or it should have a Mudsnake attachment.  The Mudsnake is a flat hose attachment like a fireman’s hose. It gives a very controlled pour and helps prevent spillage.  

Filling the Walls with a Line Pump

Sometimes a boom pump cannot be used. This is mostly because of access issues. In most cases the next best option is to pump through a line without the benefit of the boom. This is hard work and needs a few more people on site for the heavy lifting of the line. It makes for a long and tiring day.

Some thought should be given to scaffold height. With a line pump the working platform is best being at or near the top of the formwork. This minimises the lifting. Speak to the line pump company about which company to use for the concrete supply. They will know which has the best mix for their equipment. mm down

The concrete specification for a line pump should have a smaller aggregate such as “8mm down”. An oversanded mix can also help give a smoother flow. Again, take the advise of the line pump company and use their experience of the local batching companies.

The Arrival of the First Concrete Truck

When the first concrete mixer arrives on site it is good practise to check the delivery sheet. Make sure the delivery spec is the same as what was ordered. If it isn’t what was ordered send it back. Recently, ready-mix companies have stopped sending a delivery note and will email the tickets. Make sure you have the ticket before the concrete starts to go into the pump.

Do not order your concrete through a Builders Merchant. Too often, the wrong concrete is delivered. Chinese whisper effect is the reason for this. Also the merchants rep doesnt always appreciate the different types of mix for different applications.

The concrete pressure in the formwork is related to the height of the fluid concrete. Large thick basement walls take much more concrete then an above ground 150 mm core will take. Consequently, the height of the fluid concrete will be quite low with reduced pressure on the formwork.  Similarly the concrete in narrow formwork will fill higherr and create more fluid pressure due to a quicker fill rate.   

In cold weather,  the chemical reaction between the cement and the water will be slower than in warm weather conditions.  Consequently, in the winter, we may request a little longer time between concrete truck deliveries.  This is to allow the concrete  to cure for  a little longer before the next truck delivers. 

Lets assume the formwork is 3 metress high, and 36 cubic metre of concrete is needed. Lets also assume that the concrete company only has 6 metre concrete trucks. Six trucks would be needed during the day. We try to empty a truck in one complete pass of the walls. Therefore, we would pour the concrete in six x 500 mm lifts.

The vibrator is used between concrete lifts.  The vibrator should be used sensibly.

The various sections above cover the main topics for ICF construction both above and below ground. 

Do not use this as an alternative to what your chosen manufacturer recommends.  We can do things with Polarwall that ICF blocks can’t do and there may some things that you do with other ICFs that Polarwall can’t do. For example our instructions on vibrating the concrete may not be wise on some EPS block systems. 

We want to add to and develop this section, so we welcome all your questions, suggestions for topics and feedback.  If you want to go deeper into a topic please let us know.  This advice hub does not replace our training (or any other companies training) and you still need to avail yourself of our FREE training course.

Have a question or suggestion not listed here? Feel free to contact us