PRE CAST POURED IN PLACE RUBBER SURFACING
The first method for installing poured in place rubber surfacing on a vertical plane is the precast method. The pre cast method is accomplished by pre casting sections of poured in place rubber at your shop. The sections are then cut to the appropriate dimensions and installed on the vertical surface using a commercial grade urethane based adhesive. The horizontal surface in then poured, rolled and troweled into the vertical surface to create a seamless finish. The butt joint must be heavily primed to ensure that the surface bond together properly and that the seam does not separate and become visible over time.
There are a few benefits to the Pre-Cast Poured in Place Rubber Surfacing Method:
1. This method saves a lot of time over traditional methods.
2. Surface is prepared in a controlled indoor environment, allowing precise uniformity.
The detriments to this method are as follows:
1. Because the environmental conditions will be different during the curing process for the pre manufactured vertical surface and the poured in place horizontal surface, subtle differences in color and texture may be noticeable.
2. Seaming the adjoining surface together can be very difficult.
3. Seams are likely to separate over time.
FAST CURE BINDER WITH CATALYST
The problem with installing poured in place rubber surfacing vertically is that the mixture itself in its normal state is not conducive to allowing this process to happen naturally. The poured in place rubber will have a tendency to collapse on itself or to separate from the surface slightly, producing air pockets and a poor bond that will eventually produce bubbles in the surface as natural expansion and contraction take place.
In order to apply poured in place rubber surfacing vertically, the mixture must be thickened, and must be able to cure faster whilst still producing an adequate bond to the substrate. One way of making this possible is by using a fast cure binder, and speeding up the curing process using water. Water is sprayed on to the primer after it is applied, causing a hyper curing effect. This hyper curing effect makes the surface more “tacky” and able to support the rubber.
Water is also misted in small quantities into the poured in place rubber mixture itself. This also causes a hyper curing effect that thickens the rubber, making it less malleable, giving it more slump that allows it to be shaped and put into place on the vertical surface, all while being more apt to supporting its own weight.
The rubber is applied to the vertical surface using two trowels, then packed in to place. The rubber is then misted with water and troweled with diesel or kerosene to smooth and level the surface. The adjacent horizontal surface must be installed quickly and in conjunction with the vertical surface, because the hyper curing of the vertical surface will make seeming the two surfaces together very difficult if not done promptly.
Here are some of the benefits of this method:
1. It allows for a truly unitary and seamless surface.
2. If done correctly, both surfaces (horizontal and vertical) will both have the same curing characteristics, including texture, color and thickness.
Here are the downsides to this method:
1. The binders used in poured in place rubber are moisture cured. This reaction typically takes place slowly as the binder absorbs moisture from the air and the substrate. When water is added to the binder and the rubber, the hyper curing can be very unpredictable. In some cases the hyper curing can cause a foam to develop on the surface known as poly urea. This undesirable effect is irreversible if not caught early.
2. We also believe that hyper curing of poured in place rubber causes a poor bond. This can result in a surface that reaches its useable lifespan prematurely.
FUMED SILICA (CABOSIL METHOD)
This method is the best method to use, it is also the most expensive and requires the most experience working with the poured in place rubber products in this manner. This method utilizes a thickening agent known as fumed silica. Fumed silica is a clear odorless powder that when added to resins such as epoxy or urethane thickens the mixture significantly.
When using this method, the surface is primed as it would normally be. The resin is measured out in the appropriate quantities. Once the mixture has been measured, the correct amount of fumed silica is added to the resin to thicken it. The resin is then mixed with the rubber granules to a consistency of cookie dough. The fumed silica helps to not only thicken the mixture, allowing it to be applied vertically, but also provides a crystalline micro structure that helps to support the poured in place rubber as it cures, preventing it from collapsing.
The benefits to this method are many:
1. This method avoids using hyper curing as a method for vertical applications.
2. This method allows for more work time to ensure a seamless finish.
The detriments to this method are:
1. Fumed Silica is very expensive.
2. The effects of fumed silica on the resin vary greatly from brand to brand, this makes it difficult to calculate ratios for mixing.