What is Poured in Place Rubber?
Poured in place rubber consists of two layers of rubber granules bonded by a urethane binder. The bottom layer, known as the cushion layer is what provides the impact absorption for the surfacing. The cushion layer is made by utilizing shredded rubber buffings (SBR). SBR is a string like shredded rubber made from recycled tires. SBR is combined in proper proportions with the binder and installed anywhere from 1.5″- 4″ thick depending on fall heights. The top layer of poured in place rubber is known as the wear course. The wear course is comprised of small granules of rubber, either TPV or EPDM combined with binder and toweled smooth to a thickness between 3/8″ – 1/2″.
Poured in Place Rubber Surfacing is becoming a very popular choice for playground safety surfacing. Its combination of aesthetic appeal, nearly limitless design potential and unmatched non slip characteristics make it a strong candidate for playground surfacing. But there is much more to poured in place rubber surfacing then meets the eye, given the extremely high cost of this product it is important to take a closer look and get the truth about this product.
Poured in Place Rubber – Base Layer
Many installers will tell you that poured in place rubber can be installed on top of crushed stone, typically No. 57 limestone. This is the quick and easy way to install poured in place rubber, it is also the wrong way. When poured in place rubber is installed over crushed stone, it will fail prematurely, be susceptible to areas of standing water and will be lucky to last 12 months without needing to be removed. Poured in place rubber should only be installed on top of a concrete slab that has cured for at least 28 days or on top of cured asphalt. There is no other suitable base layer for the installation of poured in place rubber surfacing.
TPV and EPDM Poured in Place Rubber Materials
There are two types of rubber granules that are used in the installation of poured in place rubber, TPV and EPDM. Although these two products look the same, they are not the same. TPV is made from recycled tires, the rubber is then treated with a combination of chemicals, paints and dyes to provide its color. TPV has a much lower tear strength than EPDM. This means that if you were to try and stretch a granule of TPV, it would break, rather than stretch much sooner than EPDM. EPDM is referred to as virgin rubber. EPDM is not made from recycled rubber, it is in fact manufactured from the start for poured in place installations. EPDM is a much more durable product than TPV, it will reduce wear much better than TPV and ultimately last longer. The downside of EPDM is that certain colors are more susceptible to fading as a result of UV exposures, a problem less common with TPV.
Binders For Poured in Place Rubber
Binders are what hold the entire poured in place system together, and also hold it firmly in place on the substrate. Not all binders are created equal, and a good binder is the most important consideration for your poured in place rubber surface. There are two types of binders, aromatic and aliphatic. Both are urethane based binders. Aromatic binders are the industry standard. They are more susceptible to UV rays and also leave a yellowish tint on top of the surface, because of this tinting effect, it is recommended that certain colors not be used with an aromatic binder, particularly light colors such as white or beige. Aliphatic binders are also urethane based, the difference is that they are crystal clear and will remain so. Aliphatic binders have a much higher resistance to UV, a higher bond strength and are more stable in varying humidity and heat conditions during installation. On average, aliphatic binders cost three times as much as aromatic binders, however the cost is worth it.
Both binders are moisture cured, this means as they slowly absorb moisture from the air, they dry. Some binders will react violently to moisture, causing a foam known as poly urea. Poly urea formation will ruin a surfacing job. A good binder will be very stable when exposed to water and humidity, it will also have UV stabilizers added to it to ensure longevity. The same will be true with aliphatic binders. If a cheap, or unproven binder is used, the end result will be an ugly surface that will begin to shed and fall apart in a matter of months.
Temperature and Humidity When Installing Poured in Place Rubber
Because the binders used in poured in place rubber are moisture and heat sensitive, the environmental conditions (temperature and humidity) during installation are critical. In general you should never install poured in place rubber when temperatures are below 50 degrees or above 90 degrees, with humidity never exceeding 85%. Doing so will force a hyper curing of the product, resulting in a surface full of visible seams and blemishes, with a poor bond strength, because of this the product will fail.
Longevity and Lifespan of Poured in Place Rubber
Most people believe that poured in place rubber lasts a lifetime. This is just simply not true. If the surface is installed using a premium aliphatic binder, under perfect weather conditions, by an experienced professional and with proper maintenance it will likely last 15 years. The average life of a poured in place rubber surface installed under the same conditions, but using an aromatic binder will be 10 years. Keep in mind that if the area is shaded, it will greatly extend the life of the surface, as will doing a cap coat of binder every 24 months
The important thing to remember about poured in place rubber is that product quality and experience means everything. You can be the greatest painter in the world, but if the paint does not stick to the wall, the job will be a failure. The same is true with poured in place rubber, you must use time tested products and they must be installed under the right conditions, by experienced installers. Anything less will result in a surface that will fall apart in less than a year. For more information about how to install poured in place rubber the right way, give us a call today.