What is a piling mat?
A piling mat is a type of working platform used to provide a stable foundation for piling rigs and other heavy machinery to operate on and move around the site. They are constructed from well graded natural gravel, clean-crushed rock or clean-crushed concrete. Equally, recycled demolition materials may be used once they are well-graded and any wood or metal debris is removed.
Mats are rolled, constructed in layers and should be free-draining to prevent any buildup of water or slurry on the surface. Another purpose of using piling mats is to distribute the weight of heavy piling rigs and other equipment over a larger area, preventing the ground from becoming damaged or unstable.
What Do Piling Mats Protect Against?
Along with supporting heavy rig machinery, piling mats can protect projects from certain issues, including:
- Uneven settlement
- Waterlogging
- Ground subsidence
- Damage to underlying utilities such as water pipes and gas pipelines
Piling Mat Specifications
Piling mat specifications are critical for ensuring the safety and efficacy of foundation works. These specifications are meticulously designed to support the weight and stress imposed by the heavy machinery used for piling operations.
To determine the specifications of a piling mat, engineers need to consider multiple factors, including:
- Ground conditions, strength and properties
- Expected load of piling equipment and machinery
- Required thickness of the piling mat
Piling Mat Design & Thickness
The design of piling mats is crucial in ensuring the safety and efficiency of construction activities. Piling platform design can depend on soil conditions, the type and loading capacity of machinery being used and environmental factors. For instance, a separating membrane may be placed between the piling mat and the sub-grade on sites with a high water table to prevent the upward movement of fine-grained soils into the mat.
The thickness of the piling mat is a key dimension that needs to be carefully considered. Typically, piling mat thickness ranges from 300 mm to 600 mm. It must be thick enough to provide load-bearing capacity, making it suitable for supporting heavy machinery.
If a piling mat is too thick, it can cause unnecessary costs. In some cases, the thickness of the piling mat can be reduced by using a geogrid reinforcement. Geogrids are placed within the granular layers of the piling mat and help distribute the loads. If a piling mat is too thin, it can be more prone to wear and tear, requiring additional repair costs.
Piling Mat Installation
Generally, piling mats are installed in the following steps:
- Site Preparation – The area is cleared, excavated and levelled to create a stable base.
- Sub-base Formation – A geotextile membrane is laid and a well-compacted sub-base layer is installed using crushed rock or other materials.
- Layering & Compaction – The material is added in layers and compacted using rollers or vibratory compactors to achieve the required load-bearing capacity.
- Surface Finishing – The mat is levelled and graded for drainage.
- Testing – Load-bearing tests are performed and adjustments are made if needed.
- Final Inspection – Compliance is checked and the mat is approved for use.
Benefits of Piling Mats
Along with providing a stable foundation for heavy machinery, piling mats offer a few advantages:
- Versatile – piling mats can be constructed on various terrains and soil conditions, making them suitable for a wide range of construction projects.
- Improve Safety – by providing a stable base for operations, mat installation improves the safety of site workers and reduces the risk of accidents caused by uneven or soft ground.
- Cost-Effective – Constructing a piling mat can help avoid costly repairs to the ground, equipment, or environmental damage that may occur without its use.
- Environmental Protection – the presence of a piling mat can minimise the construction site’s impact on the surrounding environment, preventing soil erosion.
The Importance of a Working Platform Certificate
In most cases, construction projects are required to construct a piling mat to comply with local authorities and regulations. Every site with an operational piling rig must have a Working Platform Certificate (WPC). This certificate was issued by the Federation of Piling Specialists (FPS) to improve safety and working practices. A WPC states that a piling mat has been designed and installed properly and has undergone regular inspections and adequate maintenance. The certificate must be signed by the Principal Contractor and handed to the Piling Contractor before any piling work begins on site.
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