Site investigations are direct or indirect, nondestructive, destructive or semidestructive tests conducted on a structural-or architectural-element for the purpose of estimating a quantity of interest. Monitoring and evaluation procedures are performed in situ, on a soil or physical structure. These techniques are comparable to a laboratory examination in their performance, however, they are carried out directly at the affected site. Site investigations allow a specific level of knowledge of the structure to be achieved, the degree of depth of which may be at the discretion of the designer or codified in the regulations: the three levels of knowledge LC1, LC2 and LC3 assume a minimum incidence of investigation – limited in LC1 and exhaustive in LC3 – with respect to the surface area, multitude and homogeneity of the elements investigated. They fall under in situ testing:
- Cores: these are semi-destructive tests in that taking a portion of material from the cylindrical shape, the core, damages the structure without demolishing it. Crushing the specimen in the laboratory makes it possible to determine the mechanical strength of the concrete that makes up a building. Core samples are supplemented with nondestructive tests such as, to name a few, sclerometric and ultrasonic tests
- Load tests: are carried out to verify the actual behavior of the structure under operating loads. They also make it possible to determine the real degree of constraint and lateral collaboration actually developed by the structure
- Non-destructive testing
La Circular no. 633/STC introduced Dec. 3, 2019 governs nondestructive testing of existing structures and regulates on-site investigations under the laboratory regime.