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Money talks i.e. vinyl sheet piles vs steel sheet piles costs analysis
As in the case of any infrastructure investment, when it comes to civil engineering projects involving the application of a sheet pile technology, one of the most important components of the project documentation is the costs analysis, taking into account various available solutions. When estimating the total project budget, it is critical to comprehensively consider the full range of cost drivers and the pros and cons of each technology. Only then is it possible to make conscious and responsible decisions and make choices which will affect our planet and the well-being of future generations for many years to come.
Sheet piles are a popular solution for the construction of water-tight barriers in the ground, retaining and water-front structures and bank protection infrastructure. Sheet piles can be made of many different materials, e.g. steel, fiberglass or PVC. Due to the obvious differences in physical and mechanical parameters, each of the listed technologies comes with their own advantages and disadvantages.
The price of vinyl sheet piles
We deliberately do not provide a price list of our vinyl sheet piles on our website and in any publicly available information channels, and this strategy results from a number of reasons.
First of all, while invariably keeping the highest quality of our profiles, the prices of raw materials for the production of sheet piles have always been fluctuating. Due to the recent turmoil on global markets and the close correlation of PVC prices with the geopolitical situation, the price dynamics of the raw material has recently reached an unprecedented level.
The second reason why we do share the prices of our vinyl sheet piles is justified by the fact that the price of the raw material is not the only costs component under the "material" item in the project budget that should be taken into account. When estimating the final outlays related to the use a given technology, a number of other costs items and variables should be taken into account.
In light of the factors mentioned above, estimating the costs of using a given technology seems to be much more complex. In this article, we address the issue of the price of vinyl sheet pile technology, and we attempt a reliable and transparent costs analysis comparing two technologies, the first one being steel piles and the second one vinyl sheet piles.
The price of raw material
In terms of the cost of the material itself, steel sheet piles are usually more expensive than vinyl sheet piles, due to the fact that the price of steel is significantly higher than PVC. What is also extremely important, our vinyl sheet piles are made of recycled material, which not only reduces the investment cost, but also the cost incurred by the natural environment.
In addition, because our offer comprises a wide range of profiles, it is possible for us to precisely match the appropriate type of a sheet pile to the project requirements in order to maximally optimize its costs.
To illustrate the above argument, let us analyze two extreme variants of designs where both vinyl sheet piles and steel sheet piles can be used.
Example 1: a tight wall in the ground, installed to the depth of 12 meters in heavy ground conditions
Demanding geological conditions make it necessary to choose a type of sheet pile characterized by high stiffness, relatively thick walls and, above all, high weight. Let us assume that it will be a steel profile with a 11 mm thick walls and weighing 135 kilos per square meter.
Now let us choose the right type of a vinyl sheet pile. Based on our many years of experience, the recommended profile for the implementation of this type of project could be for example GW-610/7.2, which weighs 17.4 kilos per square meter. The installation of such a sheet pile in the ground under such heavy conditions must be performed using a reusable steel guide that would protect the PVC profile during assembly. Taking into account the current prices (as of February 2023) of raw material, the difference in the price per square meter between both types of sheet piles is tremendous!
The cost of the GW-610/7.2 vinyl sheet pile is only 22% of the price of a steel sheet pile weighing 135 kg/m2.
Example 2: a cantilever retaining structure that protrudes above the ground level to the height of two meters
Let us assume that the said structure is loaded with sand, i.e. we are dealing with unfavorable ground conditions for the operation of the wall.
Due to the high stiffness and bending strength of steel, a steel sheet pile with a 7mm thick wall can be used for this type of project (provided there is no aggressive environment that will result in excessive corrosion). The approximate weight of such a sheet pile is less than 80 kilos per square meter.
When it comes to vinyl sheet piles, with such a demanding project, we can only use the strongest profile, i.e. GW-458/12 with a weight of 30.7 kilos per square meter. One must keep in mind that when it comes to mechanical aspect, the strength parameter of PVC is much lower than the one of steel and a sand-loaded retaining wall like in this example will most likely reach the maximum height available for this technology.
Now let's compare the costs of both technologies, which would be also based on the prices mentioned in the previous example.
In this case, the price of the vinyl sheet piles would constitute 70% of the price of the steel sheet piles.
The price of transport
Now let us give a closer look at the transportation costs. One of the advantages of vinyl sheet piles is that they are much lighter than steel sheet piles. The density of PVC is 1.44g/cm3, and the density of steel is less than 8g/cm3, which means that from 1000 kilos of PVC we are able to manufacture much more square meters of sheet piles than when using the same amount of steel.
The density factor of the raw material makes PVC sheet piles much cheaper product to transport and they can usually be handled much more easily on site, using lighter and more cost-effective equipment. This factor makes it possible to significantly reduce the logistics expenditures, especially in the case of large projects, for which large amounts of sheet piles are used.
Let us return here to the example one assuming the construction of a tight wall, which would require 12 000 square meters of sheet piles to be completed. We know that a single transport unit can carry 1 200 square meters of vinyl sheet piles (21 tons). This means that ten such transport units will be needed to deliver the entire required quantity.
Let us now analyze the same for steel sheet piles. 21 tons of steel sheet piles weighing 135 kg per square meter means that only 155 square meters may be carried by a single transport unit. This means that 136 transport units will be needed to deliver 12 000 square meters of steel sheet piles to the construction site.
This is 13.6 times more than vinyl sheet piles!
The price of maintenance
An unquestionable advantage of vinyl sheet piles is their high resistance to corrosion. Vinyl sheet piles do not cover in rust or in any way deteriorate over time. They do not require maintenance or specialized treatment to maintain the structural integrity of the material.
Steel sheet piles, on the other hand, are prone to corrosion and require regular maintenance to keep them in good condition. Over time, this can result in significant additional costs, making vinyl sheet piles a more viable option in the long run.
Depending on the technology, the necessary anti-corrosion protection, can even add up to 30% to the cost of steel sheet piles. Not to mention the costs incurred by the natural environment as a result of such treatments.
Such corrosion protection must also be renewed on a regular basis.
The price of installation
Another important costs factor to consider when comparing vinyl and steel sheet pile technology are the installation costs which apart from the very price of installation must also consider other aspects including, inter alia, the duration of installation works.
The weight of vinyl sheet piles is much lower than steel, which results in the use of lighter and more economical equipment to deliver and handle the product at the construction site. The assembly is also carried out by fewer workers.
The direct costs of the very installation are comparable for vinyl and steel sheet piles because exactly the same equipment is used. When the assembly team is unfamiliar with the installation of vinyl sheet piles, it may be observed that the progress is slower at the initial phase of installation, until the team gets the knack of attaching vinyl profiles to the steel guides.
Summary
The price of the material itself is undoubtedly the most important costs factor that is taken into account when choosing the technology of vinyl and steel sheet piles, but it cannot be the only factor that is taken into account.
Thanks to the lower weight of vinyl sheet piles, it is possible to generate significant savings on the costs of transport, and the resistance of PVC to corrosion means that the investor does not have to take into account additional, significant maintenance costs. In addition, due to the similar assembly technique, the installation costs are similar.