Think you know about plastics in construction?

For my part, I am only going to concentrate on the plastics that are used for ground reinforcement or landscaping/civils projects. Caveat Emptor is the phrase that springs to mind and, for those of us that didn’t take Latin; this means ‘buyer beware’!
So, what type of plastics are generally used for this type of projects? Here we are talking about the process of injection moulding. Injection moulding is a process where molten plastic is pumped in to a tool or mould that forms the shape of the product that you want to create, the plastic is cooled and the product removed.
• ABS – Acrylonitrile – Butadiene – Styrene.
• PA – Nylon.
• PC – Polycarbonate.
• PP – Polypropylene.
• HIPS – Hi Impact Polystyrene.
• PET – Polyethylene Terephthalate.
• PBT- Polybutylene Terephthalate.

For simplicity, I am only going to concern myself with the two main plastics used in the landscape construction sector. PE and PP. Also, the types of these products used in the process, namely:

Virgin: Virgin plastic is made from petroleum refinement and has not previously been used for production. Virgin can be mixed with a recycled product. This process is generally carried out to reduce costs as virgin plastic costs approximately 40% of recycled plastic. The environmental costs can be far higher though.

Regrind: This is the left over from the moulding process, simply put the bits that ooze out of the mould! Associated issues with this can be:

• A breaking or weakening of the polymer chain making the finished product weaker
• Excessive fines showing as black or white spots, again causing weakness
• Contamination from other materials, wood, metal etc. Again weakness.

Recycled: From a sustainability perspective, this is best. This is the process where used plastics such as carrier bags and bottles are basically cleaned (sometimes not I am afraid!), shredded, sorted, melted down in to pellets and then used to make products in the injection moulding process. Be wary of the term ‘recyclable’ this is not recycled. Most plastics are recyclable and virgin is recyclable.

Gas injection: Usually Nitrogen gas pumped in to a mould while the plastic is still hot. The gas forces the plastic to the sides of the mould and gives a better definition to the finished product. The injection moulding process suffers from shrinkage usually. This is stopped by injecting gas, however the finished product is lighter because it is filled with air pockets. I will leave it to you to ascertain if this affects strength!

UV stabilisation: Without this, products exposed to sunlight or UV radiation can quickly break down and degrade. This takes the form of carbon black, an additive to the moulding process.

OK, so let’s take the plastics themselves.

Polypropylene

• Slippy, Low energy surface.
• Must contain carbon black as PP is particularly susceptible to UV degradation, however, this addition severely inhibits the flame-retardant characteristics of PP.
• Rigid, less forgiving.
• Degrades with exposure to oxygen
• Can be affected by microbial action when in contact with soil

Additives are given to the manufacturing process of Polypropylene to stop UV and O2 degradation, however these additives do not completely stop the process and are expensive. In this world where costs are so important, I will leave it to you to assume how much if any of these additives are used, especially when considering why a product is so much cheaper. Polypropylene is a great product, not necessarily however for hard landscaping

Polyethylene

• Similar expansion rate to PP
• Unaffected by chemicals, UV radiation, acid rain
• Excellent stress crack resistance
• Service life between 50 and 100 years
• Flexible

So, I am pleased to announce that EcoGrid/Ecoraster is made from 100% recycled LDPE (Low density polyethylene. Essentially, bags and bottles go in one end of the factory and the range of grids and accessories come out of the other, also the pallets on which they sit.

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You as a buyer don’t need to be aware. Buy EcoGrid for your long-term peace of mind.

Contact our sales team TODAY!
Tel:0151 639 4281 (4 lines)
E Mail: sales@ecogrid.co.uk.

By | 2018-01-09T11:59:48+00:00 November 9th, 2016|EcoGrid News & Blogs|0 Comments
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