In particular, the non-destructive testing of concrete (NDT) comprises the following tasks and equipment:

1. Finding the compressive endurance of concrete by using the following equipment:

• CONCRETE TESTER DIGI SCHMIDT
• SCHMIDT MATERIAL TEST HAMMER TYPE P & N

// According to international standards: EN 12398/ ASTM C805/ BS 1881 Part202/ DIN1048 Part202/ UNE 83.307

2. Finding the corresponding compressive endurance values, according to the method of ultrasounds, by using the following device:

• TICO ULTRASSONIG INSTRUMENT

Also according to the method of nails' removal, by using the following instrument:

• HILTI Tester 4

// According to international standards: ISO/DIS 8047/ BS 1881 Part201/ ASTM C 597/ NF P 18-556/ NBN B 15-229 /UNI 7997/9524 UNE 83308

Apart from the values of compressive endurance, the device TICO ULTRASSONIG INSTRUMENT or PUNDIT may also be used to find: homogeneity of concrete - cavities, cracks, deficiencies concrete and elastic limit might appear.

3. Measuring thickness of concrete with the instrument:

• OLSON CTG-1TF

4. In order to find the reinforcement of the bearing structure we use the following equipment:

• REBAR LOCATOR PROFOMETER 3&5 της PROCEQ
• FEROSCAN RV10 της HILTI

// According to international standards: SIA 162/ DIN 1045/ DGZ fp B2 BS 1881: Part204

Also for a full clarification of of the reinforcements of nodes and foundations, we use the sounding endoscope GF8.

5. In order to find the reinforcements’ corrosion we use the device:

• CORROSION ANALYSING INSTRUMENT CANIN

// According to international standards: ASTM C876-80 /BS 1881 Part201 /SIA 2006 /DGZ fp B3 /UNI 10174

6. Finding the tensile resistance of concrete by using the following instrument:

• PULL-OFF TESTER της PROCEQ

// According to international standards: ISO 4524/ CEN/TC 125 /BS 1881 Part207 /ASTM C 4541 /ACI 503-30 DIN 1048 Part2

The combination of the above method and the use of phenolphthalein determine the depths of concrete carbonation (The results of this classical method contrast to the results of measurements of sounding endoscope GF8).

7. The dynamic charge trial forced on the building, allows us to get information about the dynamic characteristics and the structure's maximum responses, as well as its seismic vulnerability. So, t is proposed to strengthen the parts of the building, where there really is a problem (referring to those structural parts presenting pathological accelerations). All the above are carried out using the following instruments:

• KINEMETRICS STRONG MOTION ANALYST
• K2 DIGITAL RECORDER
• SEQUOIA
• Dynamic Stimulators: GFT9 1200EL & GFT500-350

8. Construction’s introduction in the of antiseismic evaluation program: MANDIS-GIBFIL.

9. Geotechnical - Geophysical determination of the effective stresses on the subsoil's foundation.

10. Collection of the information that concern the bearing structure of the building (reliability coefficient data KL3) and evaluation of the remaining earthquake capacity Vc according to Greek Guidelines (KAN.EPE.) by using the computer program SCADA PRO.

Nowadays reinforced concrete is the most popular building material, as it presents the following main advantages when compared to others:

// It is economical. The materials (water - aggregates - cement) are inexpensive and easily procured. Also, generally maintenance is not required.
// It is workable and manageable. Fresh concrete can be adjusted in any form of formwork and cover practically every architectural requirement.
// It is resistant to mechanical damage and fire.
// It is deal for monolithic constructions (without joints), which as multiply statically indefinite, they have large margins of strength and security, particularly under seismic actions.

The most important property of concrete is its compressive strength. Concrete, even unreinforced, develops high compressive strength, which explains the extensive use of the particular material in construction. The uniaxial compressive strength of concrete is measured at 28 days, either on cylindrical specimens of diameter 150mm and height 300mm, or on cubic samples of edge 150mm, according to the provisions of Regulation of Concrete Technology.
So, the laboratory testing of concrete specimens is not only necessary but also very useful, due to the results obtained. In a few words, the laboratory test in which the concrete specimens received, during the concreting (or during the production of concrete) of fresh concrete with suitable patterns, are compressed by an appropriate device ("press"), until their fracture in order to determine their resistance and to draw conclusions about the construction’s strength in general.