Checklist: Compaction of the Sand Cushion and Installation of Geotextile Material

Compaction of the sand cushion

Checking the layer thickness

Before compaction, it is important to check that the thickness of the sand layer corresponds to the design requirements. To do this, use a level and a measuring tape to measure the depth of the sand layer. Make sure that the layer is distributed evenly over the entire area.

Important: The requirements for the thickness of the sand cushion established by Italian construction standards should be taken into account, for example:

• Decreto Ministeriale 14 gennaio 2008 – standards for the stability and insulation of the foundation.
• Norme Tecniche per le Costruzioni – for the design and execution of construction works, regulating the thickness of sand cushions and the strength of their compaction.

Compaction of the sand

Use a vibratory plate compactor or roller to evenly compact the sand layer. Compact the sand in several passes to achieve the required density. It is important to follow the compaction recommendations provided by Italian construction standards, such as:

• Norme UNI 10802/2013 – guidelines for soil compaction.
• Legge 1086/71 – the law regulating works related to foundations and substructures in Italy, which requires that all earthworks and bedding works be carried out in compliance with the specified density and strength.

Each layer of sand should be compacted in turn, without moving on to the next layer until the previous one is fully compacted. This will help avoid deformations and ensure the necessary strength of the base.

Installation of geotextile

Preparation of geotextile

Before starting the installation of geotextile, prepare it with the appropriate length and width to cover the entire area of the bottom of the excavation, taking into account the overlap at the joints. The geotextile must be durable and suitable for working in conditions of increased humidity, protecting the sand cushion from contamination and improving drainage.

Important: When choosing geotextile, you should be guided by Italian standards, for example:

• Norma UNI 10343:2008 – standards for the use of geotextile in construction projects.
• Norme Tecniche per le Costruzioni (NTC 2018) – rules regulating construction works and the use of materials such as geotextile.

Unrolling the geotextile

Start unrolling the geotextile along the bottom of the excavation, evenly distributing it over the entire area. Make sure that the material has no folds or distortions. At the joints between the sheets of geotextile there must be a sufficient overlap (usually 10–15 cm) to ensure reliable connection of the layers and prevent sand from penetrating through the seams.

Fixing the geotextile

Fix the edges of the geotextile with metal or plastic fasteners to prevent it from shifting during subsequent works. You can use heavy objects or stones along the edges to hold the material in place until all construction stages are completed. It is also important to take Italian standards into account when fixing the geotextile in order to comply with the requirements for its durability and safety.

After laying and fixing the geotextile, before continuing the work, you should make sure that it is not damaged and completely covers the bottom of the excavation, ensuring the stability and reliability of the entire system.

Conclusion

Proper laying and compaction of the sand cushion, as well as the installation of geotextile, are important stages in preparing the base for the foundation. By following this checklist, you will ensure the durability and reliability of the drainage system and prevent unwanted settlement and soil movement.

Compliance with Italian standards such as Norma UNI 10343:2008 and NTC 2018 will help you guarantee quality and adherence to construction regulations, which is especially important for the long-term operation of the building. Make sure that all stages are carried out accurately and with high quality in order to avoid problems at later stages of construction.