Understanding Mono-Extruded and Co-extruded Vinyl Sheet Pile
Vinyl sheet pile or also called synthetic and plastic sheet pile is an innovative earth-retention and excavation-support material alongside steel, concrete, and treated wood. Besides its high level of durability and aesthetics, it is proven to be the most sufficient and cost-effective option for hydrotechnical engineering and construction applications especially seawalls & waterfronts, flood control, and bulkheads.
Vinyl sheet pile is made from modified PVC (polyvinyl chloride). It is produced by grinding and melting recycled PVC compounds along with refining ingredients (hardness modifiers and thermal or UV stabilizers), forcing it through a mold where it takes shape, cooled, and then cut to desired lengths. The forming process is called extrusion.
Extrusion of vinyl is done in two ways – mono extrusion and co-layer extrusion. Both mono-
extruded and co-extruded vinyl sheet pilings creates high-quality sheet pile walls. In a glance, they may appear the same but actually have significant difference to both manufacturer and consumer’s end.
Mono-extruded Vinyl Sheet Pile
Mono-extrusion is a traditional process of forming different shapes and sizes of vinyl sheet profiles from single layer of material. From the word “mono”, it is composed of only one material from the core to its surfaces.
1. It only requires one extruder so fixed-asset investment is less.
2. Involving only one material and extruding machine requires lesser technical expertise to run production.
3. When scratched, the color remains the same because of its consistent composition from outer layer to the core.
1. Due to one-material composition, the core of the sheet pile has the same ingredient as in its outside surface. This makes mono-extruded vinyl profiles considered unnecessarily expensive because ultraviolet (UV) inhibitors, typically the most expensive ingredient in the mix, are present in the core where they are actually useless.
2. Color of mono-extruded vinyl sheet piles can vary from batch to batch of production due to variety of raw material sources.
Co-layer or Co-extruded Vinyl Sheet Pile
Co-extrusion is a modern process in producing vinyl sheet piles that works by extruding two compounds at the same time to form a desired profile. It typically involves using a cheaper substrate material to give the sheet its mass and a more superior outer layer called “capstock” to protect the exposed surfaces primarily from UV radiation.
1. The capstock provides a high degree of UV protection to the sheet pile. Due to the optimized formulation of the protective layer, some manufacturers guarantees their co-extruded plastic sheet pile products to beyond 50 years of of lifespan.
2. Co-extruded vinyl sheet piles are cheaper because the core material does not necessarily contain ingredients such as UV inhibitor. The core is formulated to develop more of impact-resistance rather than UV resistance.
3. The combination of high-strength substrate and high-performance UV protection layer allows construction of taller walls and enhanced drivability of sheet piling into deeper and more difficult grounds. This is basically the principle of extruding two different materials, focusing strength to the core and protection to the outside layer.
4. High-quality capstock provides color consistency unlike mono-extruded materials which has tendencies to vary in color or shade by batch.
5. Overall, they are more cost-effective than mono-extruded sheet piles due to the strategic concentration of two materials with different strengths.
1. When scratched, the damaged portion reveals a different color which is the color of the substrate.
Which Material is Better for the Consumers?
Key features such as strength, durability, and UV performance are considered equal for both extruded profiles. Manufacturers of mono-extruded and co-extruded vinyl sheet piles also offers the same length of warranty as a result of the confidence built upon the promising track records of both materials. However, there is one aspect that separates the two finished products - cost. Co-extruded plastic sheet piles appears to be slightly more economical with the added consolation of long lasting beautiful appearance.
However, there are other critical factors that may affect the product cost and concerns both manufacturers and consumers. They are as follows:
1. Co-extrusion requires bigger investment in equipment which also affects the market price of end-products.
2. Mono-extrusion requires smaller equipment cost but higher material cost. In this case, fixed asset cost is low but raw material prices are volatile, thus, pro duct prices can also be unpredictable.
3. Co-extrusion has more complexed operations and requires higher level of expertise. Manpower skill in this case is a critical criteria that controls quality and safety matters.
ESC is a world-leading provider of all kinds of sheet piles – vinyl, steel, and FRP. Yes, we have it all, plus we have our highly-experienced professionals to attend all your sheet piling needs and queries. Let us be of help to provide the best option and value to your project. Please contact us at www.escsteelphil.com