There are multiple reasons why you might need to use a pile foundation type. Whether because the top layer of soil is weak, there are too many obstructions in the soil, you want to cause minimal disturbance, or because you’re working in water or an area prone to flooding. But once you know that piles are required, you’re faced with deciding which pile type will best suit your needs. And a question we’ve been asked recently is how screw piles compare against precast concrete piles. So, that’s what we’re going to look at in this blog.
Screw Piles vs. Precast Concrete Piles
What are screw piles?
Screw piles, also known as helical piles, are tubular stainless steel structures with an external helical flight. They are designed to screw directly into the ground, and are available in a range of widths and lengths to suit the weight bearing needs of any given structure.
What are precast concrete piles?
Precast concrete piles are piles created from reinforced concrete. They can be moulded into a range of shapes – circular, square, rectangular, or octagonal – and are cast and cured by a professional provider before being transported to a construction site for use.
What is the difference between screw piles and precast concrete piles?
There are a couple of main differences between these two piles. The most obvious is the material. But there is also the issue of installation. Helical piles can be quickly screwed into the ground either manually or with a common groundwork’s vehicle, with very little disruption. While precast concrete piles must be driven with an impact pile driving hammer. This can be incredibly noisy and disruptive to the local environment.
What are the pros of screw piles?
- Screw piles can be installed quickly and efficiently. They can be installed manually where space is tight. Or using a range of groundwork’s vehicles where there is better access.
- Post-installation, screw piles are ready for immediate use. They need no time to set and can carry their load straight away, meaning there are no delays on site.
- Screw pile installation causes minimal noise or ground disturbance, making them a strong candidate for built-up areas.
- It is possible to measure the torque of screw piles during installation to ensure the best load-bearing capability.
- Screw piles can be installed in a variety of conditions and soil types, including sand, as well as in water and flood-prone areas. They are also a good choice where there are obstructions in the ground, such as tree roots – that’s why they are frequently chosen for sites where a Tree Preservation Order is in place.
What are the benefits of precast concrete piles?
- Precast concrete piles can be driven into water and used in flood-prone areas, providing support where many other foundation types would fail.
- The reinforcement within the pile is highly unlikely to be moved or degraded.
- Precast concrete piles enable better quality control than poured concrete piles. And any flaws can be easily identified and rectified before the piles are shipped and driven.
- The piles can be produced n a variety of shapes to suit the needs of the build.
- Precast concrete piles are durable, providing high resistance to any chemical or biological actions in the soil.
- The piles can be cost effective if you are having a large number produced.
What are the cons of screw piles?
- Screw piles are not suitable for gravel, rock, or soils that contain large rock obstructions. So, if the grain size is more than 60% of the pitch of the helices, screw piles should not be used.
- It’s important to be aware of torque limitations when installing screw piles. If too much torque is applied, the integrity of the screw pile can be compromised.
What are the cons of precast concrete piles?
- Precast concrete piles can be extremely difficult to handle. They are phenomenally heavy and require specialist equipment to transport and manoeuvre.
- The piles are prone to breaking during transportation, so extra care must be taken.
- Specialist equipment is required for the installation of precast concrete piles.
- Pile installation can be incredibly noisy and cause a lot of ground disturbance, which can make them unsuitable for built up areas.
- Concrete is known to be one of the worst pollutants, causing up to 8% of global CO2 emissions. This can make precast concrete piles an unpopular option for brands concerned with sustainability.
- Pile lengths are restricted by the ability to transport them to site, and it is not possible to change the length of the piles when on site. You can’t extend them, and cutting them can be extremely difficult.
- Precast concrete piles can be expensive because of the need for superior reinforcement.
There are advantages and disadvantages to every construction foundation type. And there will be circumstances in which it would be folly to attempt to install screw piles, or where precast concrete piles provide a clear solution. You can only base your decision upon the features of each individual project. But in many circumstances, there is a case to be made for the use of helical piles.
Get in touch with UK Helix to discuss the needs of your next construction project.