One of the most difficult processes in building foundation walls which also causes delays and cost in inspections is the use of Standard Rebar Steel. Even with ICS construction the use of standard half inch rebar is built into the forms because it is required by code.
First to understand the differences you need to understand why rebar is used in any concrete application. Concrete in and of its self is a hard surface that can be used for many applications but structurally it is brittle. If you were to apply a load on a concrete driveway that had rebar and one of the same thickness and concrete mix properties then the one without rebar would fail under a much lighter load. The same problem occurs in foundation footings, foundation walls and above ground walls. Anywhere concrete is used if it will be under load it should have rebar. You can think of this similar to a wall tile. The tile alone is brittle but it is hard and you could probably snap it in half with your bare hands. Concrete is similar but to improve its strength you need to use rebar.
What is the difference of Micro Rebar and Standard Rebar in Concrete
The first difference is the way the material is introduced into the concrete. Standard rebar requires the use of a structural engineer or architect that understands the properties of the entire building and can lay out a rebar structure. Although General Contractors normally can build slabs and other basic structures following normal standards of rebar detail the use of a professional to lay out the exact dimensions, spacing, overlap and other properties is normally required.
Micro Rebar is introduced into the concrete mix and for that reason it is spread evenly throughout the mix without the need to consider spacing or other rebar design properties. You simply specify the amount of micro rebar to the mix ratio and you end up with a mix that is structurally sound.
Time considerations and trained crews to layout the standard rebar is always a final cost factor. If you have a crew that lays out the rebar incorrectly and you are waiting on inspection then your project can be delayed if your layout is incorrect. This is true with any structural inspection throughout your project. The cost of materials to fix a mistake might be minimal but the cost to relay the rebar and have another inspection will delay all other aspects of your project.
How Is Micro Rebar Best Used
Since Micro Rebar is introduced either at the batch plant or at the truck prior to pouring it is best used in areas that use forms such as ICF insulated concrete form construction.
The use of Micro Rebar in an ICF wall means that you can install the wall forms without consideration and time need to tie standard rebar and then pour the wall as soon as your forms are ready.
The use of Micro Rebar in a pump truck should not be a problem. The size of the zinc plated rods is about the same as a standard brad nail and they will flow through the pump without clogging.
Concrete with Micro Rebar can also be finished like standard concrete. Just like you would float a slab to lower the stone in the mix and achieve a smooth surface the micro rebar can also be floated and finished in a variety of methods.
Shot concrete is another approved application of this material but you will need to contact your manufacture about this specific application in your project.
Final Note
Although Micro Rebar has proven its self in the industry over the past few years you might still run into problems with your mix plant or inspector. It would be a good idea to find out if your local plant uses this product early into your planning stage and not try to force the material on them when the truck gets to your site.
This seems like a good product that can be used in many applications to speed projects. Theoretically the material should last and standard rebar will deteriorate over time so the idea of using this material should not be a problem.
I would expect that most projects will still be overbuilt and a mixture of standard rebar and micro rebar will be used to ensure minimal standards.
Because this material is very easy to introduce into the concrete just like fiberglass it should eventually replace standard rebar in many construction projects.
Do I suggest you use this product?
If it is available and you are using the ICF method of building I would consider it. If you are building a standard residential home with a slab floor and poured walls then it is not a huge advantage in time and materials but it could be on larger homes.
If you want to over build your home in an area known to have problems such as earth quakes or are building above ground concrete walls in tornado or hurricane areas adding this material to your mix in addition to standard rebar use is something i would consider.