Everyone loves a trilogy right? Turns out I've written one without ever planning to!
This is now my third consecutive blog post related to reinforcing concrete. The first covered the use of reinforcement bars around openings for hobs, sinks etc. The second discusses the placement of reinforcement within the concrete itself to maximise the strengthening properties. And in this one? Well this is how to reinforce the concrete without ACTUALLY reinforcing it.
This really relates to thin profile concrete and specifically to our GFRC Worktop Premix. The main benefit of GFRC (Glass Fibre-Reinforced Concrete) is that you can make it very thin. We recommend 18mm as a minimum thickness. Getting any form of extra reinforcement into something so thin can definitely be a challenge. Breakfast bars have long since been very popular - they add a very social element to your kitchen and are as suitable for wine o'clock as they are the first meal of the day!
For a breakfast bar to be functional, it needs to be about 300mm deep (or 12 inches in old money), just about the right length for your knees to fit under but coincidentally at 18mm just the right length for the concrete to droop if not bolstered in some way! If you don't believe me check out the island countertop in my own kitchen!
I rushed the concrete because we were on a tight timescale fitting it in between paying projects. And because I rushed, I completely missed out the part where you add reinforcement! Let that be a lesson to all of you who rush things and don't plan properly!
If I'd had my wits about me I could have thought a little outside the box and made sure what I was resting my concrete island upon was a little more than just thin air.
If I'd installed a plywood base for it to fit onto that may have sufficed but in all likelihood the plywood have just drooped with the concrete and I would be no better off.
So something a bit more substantial is required and I'm not talking a lot. Just a few lengths of angle iron or similar are absolutely perfect. Just like the rebar the angle iron should half support the overhang and the other half be affixed to the structure of the island carcass.
In the example below the angle iron almost runs across the entire width of the island. Over-engineered? Possibly. Will the concrete every droop? Nope. Is it worth it for the extra effort and minimal cost? Definitely!
As you can see the angle iron is just less than the thickness of two sheets of plywood so some consideration has to be given in terms of design but it's not a particularly technical ask. Here are a few more detail images below to help you visualise further!
