GFRC Concrete & concrete countertop Process

Modern Concrete creates its countertops and other products using a superior GFRC concrete & concrete countertop process, or glass fiber reinforced concrete, instead of traditional concrete. GFRC differs from traditional concrete due to its replacement of large aggregate and steel with a network of glass fibers in a mix of Portland cement, sand and a polymer. The combination of cement, sand and glass fibers form a matrix which gives the concrete great flexural, compressive and tensile strengths. This allows the overall product to be much thinner and lighter than traditional concrete. Traditional concrete, or Wet Cast as its commonly referred to, requires the use of Portland cement, sand, large & small aggregates (typically stone) and steel (wire mesh & rebar) reinforcement as a means for added strength. It also needs to be thicker and therefore much heavier. GFRC is typically around 8lbs per sf as opposed to 18lbs per sf for wet cast

HOW IT BEGINS:

In the process of GFRC, we begin with spraying a thin layer of concrete, known as a face coat. The face coat is sprayed on the entire inside covering of the concrete countertop mold (forms). The face coat is what you will see as the outside of the finished product once it's de-molded. IE: This layer is what becomes the top of the countertop or sink. A stiffer mix or backer coat, containing a large amount of AR fibers (alkaline resistant glass fibers) is then hand placed (aka hand packing) into the form. This mix is used to create sinks or build up vertical edges. Backer coats are then layered and applied in several coats. The final mix , if needed for flat horizontal areas, is very liquid concrete mix called SCC. Self Consolidation Concrete mix contains a large amount of glass fibers along with a super plasticizer. The plasticizer helps make the mix flow very easily and allows it to self-level filling the horizontal sections of the mold.

The concrete is allowed to harden and cure for a period of 12-24 hours typically. It is then removed from the molds (forms) where the finishing process begins.


 To see our products using this method, click here.

THE FINISHING:


Finishing begins with either wet or dry sanding. Wet sanding (aka wet polishing) uses diamond pads and water to expose sand and aggregate if that's the desired look. If no aggregate exposure is desired the concrete may simply be dry sanded and etched so that the cream coat remains. This also provides a tooth for the sealer. Slurry coat(s) of cement with and/or without sand fines are applied next. These fill in voids and pinholes in the surface. It is once again sanded and cleaned after each slurry application until ready for sealer. Sealer is apply in several steps over several days with 4-6 coats and hand applied. Once the sealer is applied there is it curing time of several days before the concrete sink or counter can be installed and ready for use due to the cross linking of the sealer with the concrete.


To see our products using this method, click here.