We recognise, observe and foresee problems by analysing the land deep-down, including physical perturbations, monitoring and observing values and indicators that can help prevent them.
In order to do so we have converged different fields of competence, from geology to engineering, geophysics and geotechnics, integrating an approach that respects nature, ecosystems and infrastructures, thanks to non-invasive technologies. This has culminated in profound knowledge, combined with the ability to anticipate and monitor criticalities of sites, areas and human works.
Masonry testing
The purpose of such testing is to estimate the compressive stress state on a portion of masonry, during testing. This method of investigation involves making a flat cut, normally in the main direction of tensional stress in masonry, into which a flat jack is inserted, before being connected to the circuit of a hydraulic pump. The internal surfaces of the cut are stressed with a known pressure that is gradually increased, enabling a return to the initial condition, namely the annulment of deformation measured after the cut was made. This is measured using relative distance measurements between couples of analogous points arranged symmetrically to the cut. Reference standard: ASTM C 1196 – 09 and ASTM C 1197 – 04.
The purpose of testing is to estimate the deformability (and/or breaking) value of a portion of masonry between two flat jacks. The test consists of making two flat and parallel cuts at a known distance, into which two flat jacks, connected to the circuit of a hydraulic pump, are inserted. The portion of masonry under investigation is stressed with loading and unloading cycles and deformation is measured using at least three displacement transducers in a vertical and symmetrical position, mid-way between both jacks. In this way, the elastic module, the load/deformation curve and the tensile strength of the structure subjected to investigation, are all obtained. Reference standard: ASTM C 1196 – 09 and ASTM C 1197 – 04.
The direct cut test is used to estimate the average shear strength of brick structures. The test involves the lateral (horizontal) sliding of a portion of masonry (generally brick), suitably and laterally isolated from the rest of the structure, using the thrust generated by a hydraulic jack. Reference standard: RILEM MS-D.6; ASTM C1531 – 16.
Visual examination with an endoscope enables the direct visual inspection of the consistency and nature of material of the section of masonry under investigation, with the characterisation of any anomalies. The endoscopic probe consists of an optical group with a light source positioned on the tip, which transmits images to a monitor, through the cable. Images can be memorised either as footage or photographic images, which can be used to extrapolate further details during processing, using a PC.
Thermographic investigation is a non-destructive technique that is only used to investigate the surface layers of a product, by detecting infrared radiation emitted or reflected by objects. Differences in conductibility and thermal inertia of deep construction elements mean that the thermographic camera can map surface temperature. An image in a scale of colours or greys is obtained, corresponding to a temperature interval in the order of fractions of degrees centigrade, thus discerning the different composition of type of material. Readings are taken without any contact with the surface of the analysed structure. Reference standard: UNI 10824-1/2000.
Continuous core boring is a type of mechanical investigation involving the drawing of material from the structural element under investigation. This type of investigation enables direct sample observation, so that the stratigraphy of masonry can be obtained, along with the identification of any anomalies and discontinuities within it. Coring can be carried out with the purpose of analysing internal masonry composition and to evaluate the depth of the foundation laying surface of the structure under investigation. Reference standard: UNI EN 12504-1
Tests on reinforced concrete
Magnetometric (pacometer) testing is used to identify reinforcement bars in reinforced concrete structural elements, to measure the thickness of the bar cover and to estimate bar diameter. The technique is based on the principle of magnetic induction, as the localisation of reinforcing bars is possible thanks to the magnetic properties of iron. Reference standard: BS 1881-204/1988.
Sclerometric testing is a non-destructive surveying method used to obtain information on the quality and homogeneity of concrete, by measuring the surface hardness of the material. The test involves measuring the rebound height of a conventional mass launched with a constant kinetic energy, against the surface of the structural concrete element under investigation, using a spring of known stiffness. The rebound index is proportional to the surface hardness of concrete. Reference standard: UNI EN 12504-2/2012.
The drawing of samples from concrete is carried out by means of continuous coring in concrete, using a manual or automatic corer. The purpose is to enable the physical, chemical and mechanical characterisation of the drawn sample. Reference standard: UNI EN 12390-3/2009, UNI EN 12504-1/2009.
The purpose of ultrasound testing is to determine the velocity of propagation of ultrasound through concrete, which is directly correlated with its resistance to compression. In ultrasound testing, the propagation time of elastic longitudinal waves between one or more couples of sampling points is measured to obtain information on the homogeneity of concrete. Equipment includes a generator/receiver of electric impulses, a transducer and a calibration bar with a known propagation time. Impulse speed can be measured directly (by positioning the transducer and receiver on opposite façades), semi-directly (positioning the transducer on a surface and the receiver on an adjacent side), or indirectly (positioning the transducer and receiver on the same surface). Reference standard: UNI EN 583-1/2004, UNI EN 12504-4/2005.
Determining the depth of carbonation
The test is used to determine the depth of carbonation, starting from the surface layers of concrete. The test can be carried out on core samples or on site, by chiselling the structure under investigation. Normally the pH value of concrete is close to 13, so as to avoid oxidation phenomena in the reinforcement structure contained within. The test consists of spraying a 1% phenolphthalein solution in ethyl alcohol on a portion of the structure under investigation, to detect any lowering of the pH level, which if greater than minimum bar cover thickness, would result in oxidation phenomena in the reinforcement structure.
Determining the penetration profile of chloride ions in concrete
This method of investigation is used to quantify the spread of chloride ions within the structural element of concrete. Therefore the depth of chloride ion penetration is quantified to define the line of separation between the penetrated area and the area that is not yet contaminated by ions. Reference standard: UNI EN 12504-1 and UNI EN 11747.
Metalwork fabrication samples are drawn from a reinforced concrete structure to enable physical, chemical and mechanical characterisation. A pacometer is used to identify the reinforcement bars; they are then extracted and tested for resistance to yield, breaking and lengthening; chemical composition and weldability are also tested. Reference standard: UNI EN 10002-1/2004.
The SONREB system is based on the combination of results obtained through sclerometric and ultrasound tests, correlating the velocity of ultrasound waves (SONic), the rebound rate (REbound) and resistance to compression of concrete. This provides a more accurate estimate of the condition of concrete in the area under investigation. Reference standard: UNI EN 12504-2/2012 and UNI EN 12504-4/2005.
The purpose of durometric testing is to estimate the hardness of steel, which in turn is used to evaluate resistance to traction through direct correlation. The method is based on measuring the loss of energy in a body thrown against the object under investigation. Reference standard: UNI EN ISO 18265 – DIN 50157
Tests on composite materials
Pull-Out testing is a non-destructive method for evaluating the mechanical qualities of reinforced concrete. he force required to extract a plug is measured, which may already have been incorporated within the concrete cast, or fitted once the concrete was already hardened. In this way information is obtained on the cortical layer of the structural element under investigation. Reference standard: UNI EN 12504-3.
The purpose of the Pull-off test is to verify that adhesion has occurred between the support and outer layers of concrete coating, like malts, plasters, waterproofing material, etc. The method involves the application of an increasingly heavy load onto the surface under investigation, until the element detaches or breaks. Resistance to traction and tearing of the masonry or cement conglomerate wall coverings is measured in this way. Reference standard: UNI EN 1015-12/2002, ASTM – C1538/04, UNI EN 1542/2000, UNI 12636/2001. Reference recommendations for applications with composite materials: CNR-DT 200 R1/2013, C.S.LL.PP. 24th July 2009.
Special testing
The purpose of load testing is to verify the stability and resistance of the structure under investigation. Specifically, tests subject the structure to maximum tolerable static stress, at least as declared in the project, once more within the scope of service actions. Such testing can be carried out with a concentrated load (pull or push), or with a load distributed over works requiring reconstruction or rebuilding from scratch.
Georadar, or GPR (Ground Penetrating Radar) is a non-invasive system for surveying the subsoil, suitable for modest depths and based on the reflection of electromagnetic waves. This technique is mostly used in underground utility investigations, including manholes and pipes, for the identification and mapping of existing installations, the identification of the geometric structure of foundations, and the identification of masonry structures and cavities. Short electromagnetic impulses of varying frequencies are emitted, which upon meeting surfaces with different physical characteristics (different dielectric constant or electrical conductivity), are partly reflected (so they return to the receiving antenna) and partly transmitted in the subsoil. Maximum depth and the consequent degree of obtainable detail varies according to the frequency used. A low frequency enables information to be collected at grater depths, whereas high frequencies are desirable when aiming for better resolution for surface targets. The antenna is made to slide along a previously defined straight line (usually a rectangular grill is created), to obtain a real-time radargram in digital format on a PC monitor, which is successively elaborated and interpreted using specific software.
Ultrasound tomography is a non-invasive technique for the investigation of high-thickness concrete elements, like tunnel cladding and post-compression sheaths, as well as the condition of reinforcement and stone structures. Tomography involves the reflection of short elastic impulses of waves (P or S), off cracks, cavities, reinforcements and other discontinuities and anomalies present in material. The advantage of this type of equipment is that 2D tomographies can be obtained along an orthogonal section of the surface of the product, even with structures accessible from one side only. By repeating the evaluation on a regular grill of points, a 3D model of the internal structure of the product under investigation can be obtained.
Pile integrity testing is carried out using the Pile Integrity Tester (PIT). This kind of testing is used to verify the presence of significant defects inside foundations, including breakages, significant size variations and cavities, before proceeding with construction above. It can also be used to test piles already integrated within the structure, like support foundations on bridges or towers, and to evaluate their length.