Geotechnical Tests

A full geotechnical report is required by law if you want to build a property on any site in Spain. These tests are very important and will also be needed later for your 10 year structural guarantee.

There following information is obtained from a typical geotechnical test.

• The density of the terrain.

• The dampness of the ground.

• The general composition of the ground: soil, sand stones, rock etc

• The aggressiveness of the ground to concrete, both sulfate and acidity tests

• The ability of the ground to absorb water.

• The stress and strain properties of the ground.

What actually happens on site is the following:

A soil sample is taken from where an excavator opens what is called a “calicata”, basically a hole in the ground as deep as the excavator can go to extract the sample. The number of calicatas may vary depending on the size of the plot and the composition of the ground.

A pile drive test is carried out where a steel pile is driven into the ground and the number of hammers with a 75 kilo weight is calculated for each metre in dept the pile is driven. Should a pile drive be unable to reach the dept you expect to have your foundations then a sample is taken from the dept reached. The normal dept that is reached is between 4 and 10 metres.

Note: If a plot has been filled and the pile drive goes beyond the expected dept a more expensive drill test is required. The drill test takes samples of the ground at all levels as the drill goes down and these samples are stored in special boxes for analysis in the laboratory to effectively decide what type of foundations are needed for your build.