WHAT IS GRC ?
WHAT IS GFRC?
AND WHY ARE THERE TWO ACRONYMS?
GRC is an acronym for Glass Reinforced Concrete.! GFRC is what the Americans refer to it as, Glass Fiber Reinforced Concrete! ?? . It was the British who developed ARG what is ARG and coined the term GRC and this new composite industry , coming from this half of the globe I have always referred to it as GRC. . It is actually an engineered composite and not at all a concrete , so all in all the names are confusing and very hard to narrow down in a search engine.
Our expertise is in Decorative GRC as opposed to industrial GRC . We have had the freedom to push the boundaries in decorative manufacturing and composite development as we are not bound by Building codes or specifies telling us how we must produce our products or what formulation we must use . Check out Bouncing cement! Bouncing cement
WHAT IS DECORATIVE GRC?
Structural Engineers seeing the obvious advantages of GRC in Architectural construction where the first people to develop GRC composite materials and they developed an industry to comply to their requirements.
What is decorative GRC ? Decorative GRC was the redefining and re-engineering what had been developed into an industrial process into a refined studio based process geared to producing smaller delicate decorative artifacts.
As an artificer involved in the arts The first task I had in 1995 when I moved from casting Bronze sculpture to casting GRC décor was to re-engineer Industrial GRC materials and processing to the smaller scale detailed level that was needed for an ART reproduction industry, as well as processing equipment we also had developed new finishes that would take the perception away from being just cement artifacts! DECORATIVE GRC is 15 years of development in Decorative manufacturer. To get to this point I have had to develop and refine new processing equipment , the chemical finishes , the design specifics, the procedures, the products and the markets !, As selling into a Garden décor retail industry who where use to pre-cast concrete, and lower end cheaper product has been a challenge to educate , the public have been easier to educate they have been quick to recognize and absorb Decorative GRC into their homes , offices and gardens.....
Hand Lay Up
Prechopped ARG
There is GRC and there is GRC.
Anyone who would add Glass Fiber Reinforcement to any! Cement composite can call it "GRC".
“Hand layup “ is often referred to as “ Pre-mix “GRC. This is a completely different process and a completely different composite material to “Spray up” GRC.
Hand layup is more common as it does not require specialized equipment to process, basically a sand and cement slurry is prepared into which pre-chopped AR glass fiber is added in additions between 2 and 3 % the fiber is dispersed into the slurry with a low shear mixer as not to break up the fiber into micro filaments, refer to detailed data in what is ARG . The pre-mixed fiber cement composite is then cast into a mold under vibration or applied to a mold surface by hand.
So what is the big difference between hand layup and spray up GRC ?
Best described by this analogy! If you take a bucket containing a premixed slurry of water, sand and cement and to this slurry add chopped fiber a handful at a time and mix it in, eventually the mix will become saturated in fiber and will no longer be workable, once saturated it can no longer be poured or even spread onto a mold surface evenly ! When the slurry is this saturated in fiber, the fiber % will be just over 3.5% !!!! .
Spraying the composite of fiber and cement simultaneously onto the mold surface in a single operation, it is possible to build up a matrix that contains above 5% fiber, a fiber ratio not possible by pre blending fibers .
If we look at a graph of the mechanical properties of GRC plotted against fiber % we will see that above 4 % the curve climbs exponentially. In other words the mechanical advantage or fiber reinforcement that we are looking for begins only over 4 %. fiber volume % below this as in Hand Lay up or Pre - Mix , the properties although better than unreinforced pre-cast just do not have the dynamic mechanical properties that Spray Up GRC with 5-6 % fiber demonstrates !
So lost are the general Public as to what this new material "GRC" is and to the vast difference in performance between pre mix and Spray up GRC that I have always tried to define “Spray up” GRC in Decorative manufacturer as a separate material to hand lay up ! Which it is it is, lighter, stronger and its mechanical properties are vastly improved.
In summary Hand layup GRC could be described as cement slurry that contains reinforcing fibers. Where spray up GRC is best described reinforcing fibers that contains some cement!
Rondel and sout in Hand lay up GRC . rondel in bronze acid stain , spout in real iron finish
SPRAY UP GRC
SPRAY UP !
Glass Fiber Reinforced Concrete
Spray up GRC is a process of Spraying a composite of fiber and cement simultaneously onto the mold surface in a single operation. In this way it is possible to build up a matrix that contains above 5% fiber, a fiber ratio not possible by any other method. (Spraying of a Pre-mix, of slurry and fiber through a pumping device and spluttering it onto a surface is not spray up GRC . Spray up GRC has over 5% fiber; the fiber length and orientation are controlled by the spray gun parameters. This requires specific equipment, knowledge and skill as well as a discipline to procedures.
Sprayed GRC composites are actually formed by a spray and roll process. The rolling is done with a special roller that compacts the composite against the mold surface after it is sprayed. The composite is usually built up by spraying and rolling several layers
WHAT IS ARG
his image is of a Spool of ARG. Alkaline Resistant Glass referred to as Roving
The spools are used in Spray up GRC and is chopped into length by the Spray chopper gun GRC spray head
Hand layup GRC uses the same fiber but it is already pre chopped into short lengths usually between 1 to 3 inches.
The Roving is made up from micro filaments only 14 micron in diameter, these micro filaments are gathered into "Strands' The strands are gathered to make up the Roving . how many micro filaments in a strand and how many strands in a Roving determine the class of fiber , depending on the application you may use different classes of Roving .
The micro filaments are glued together to form the Strands with a water soluble glue to keep the Roving intact while it is being sprayed or mixed, it is important that the chopped roving is dispersed evenly in the cement matrix . In Hand lay up over mixing will dissolve the glue binding the Strands and the micro filaments will begin to separate and disperse, not good! So in hand layup low shear mixing is used to disperse the chopped fiber into the slurry but not break up the Roving. Spray up does not have this problem as the fiber is chopped and sprayed with the slurry in a single operation.
“ARG” Alkaline Resistant Glass is nothing like “E Glass” used in fiberglass manufacture! ARG technically is more of an advanced ceramic than common glass with 3-4 times the tensile strength of steel , but only ARG doped with 14-17% zircon will last in the alkaline environment of Portland cement .
ARG is also produced in low % zirconia for use in Low or non-alkaline cements like CSA cements, these low zirconia ARG are of course cheaper than the high % zircon doped ARG but will fail if used in ordinary Portland cements . There are unscrupulous manufacturers or new entrance to the industry without the knowledge who produce GRC which is not to any standard. Buyers beware!
The strength to weight ratio of Spray up GRC has opened the door to design and scale possibilities that have just not been possible or practical in Precast concrete simply because they would be too heavy. An earlier version of this Urn below was first developed and manufactured in 2002 . The product has been so successful commercially that I have refined this Form several times over the years into what you see today and its success is more of the fact that there is little competition in decorative urns at this scale than simply the design.
The following page extract from one of our early "Stoneaccents" catalogs 2005 This product best defined the scale, strength and weight of the decorative spray up GRC. This product was 1.8 meters high and weighed only 50 kg . Hundreds of copies of this urn where sold and shipped to Europe, Australia from 2003 and still sells today . Some Designs become Classics, this is one of them.
