Absorption (RILEM) Testing

The RILEM test method provides a simple means for measuring the rate at which moisture moves through porous materials such as masonry. The test can be performed at the site or in the laboratory (on samples removed from site) and can be used to measure vertical or horizontal water transport. Because masonry building materials are porous to some degree, they are all somewhat susceptible to rain water infiltration.

Anchor Mapping

With the use of GPR and metal detection, anchors and wall ties can be mapped on site and transferred to drawings.

Moisture Infiltration Survey: Basements

A specific NDE testing program can be devised to identify sources of moisture and extent of infiltration.

Techniques include

• RILEM Tube Adsorption testing
• Infrared Thermography
• Electrical Capacitance Testing
• Spray / Flood Testing
• Moisture Meter monitoring

Blower Door

A blower door can be used to lower the pressure within a building unit, increasing air flow through existing areas of leakage such as poorly sealed windows and doors.

Combined with thermography, the blower door provides exaggerated thermal differences that correlate with deficiencies in construction and insulation, that may otherwise go unnoticed. This can help to provide a targeted approach to improving building envelope efficiency.

Condition Assessments

Building surveys include a NDE testing program that utilizes a variety of tools in conjunction with visual survey.

Surveys can be conducted on a variety of building types, both new construction and historic. Surveys can cover the interior or exterior building envelope or focus on specific features or issues, such as moisture infiltration, parapet walls and roofs.

Findings are then translated into drawings that can inform future repair design.

CCTV

A remote CCTV system allows for video footage to be collected within drain pipes or other small areas where access is available. Useful condition assessment information can then be retrieved during a visual review of the footage such as identifying material loss, corrosion, debris, blockages and standing water.

Data is reviewed in real-time during the survey and recorded in standard .AVI format.

Conduit & Rebar Mapping

GPR and metal detection can be used to identify and plot subsurface objects on site.

Findings can be translated into accurate drawings to fit the needs of the project.

Coring and Probing

Though not non-destructive investigative methods, cores and probes are sometimes required to assess underlying structural elements and gain samples for further testing. Cores and probe areas are selected to be the least conspicuous and minimally invasive.

Probing has been used to identify historic structural steel connections in a warehouse, after which on site investigation and measurements were translated to detail drawings (below)

3D Photographic Model: Measurable, interactive 3D model of probe section. Click to view

Impact Echo

Impact Echo is used to assess the mechanical properties of structures such as integrity, strength and form. GBG uses IE in accordance with the ASTM standard C 1383-98.

Impact Echo uses tuned hammers to pass pulses of acoustic energy into the material in question. The acoustic energy causes a response which is then analyzed in order to understand the form and mechanical properties of the materials. Ultimately this information can be used to assess and map voids, cracks, and delamination.

Electrical Impedance

An electrical impedance (EC) meter measures variations in roofing materials and can be used to identify areas of wet insulation. EC scanning is best utilized in conjunction with a thermal imaging survey to providing complimentary data results.

Flat-Jack Testing

Single and double flat-jack tests and hydraulic ram jacks are used widely for assessing the mechanical characteristics of unreinforced solid-unit masonry. These techniques are the most versatile in-situ test procedures for estimating masonry walls' main mechanical properties, all standardized by the American Society for Testing and Materials (ASTM).

In Situ Measurement of Masonry Deformability Properties (ASTM C1197)

In Situ Measurement of Masonry Mortar Joint Shear (ASTM C1531)

GPR

Ground Penetrating Radar (GPR) provides a method for the internal assessment of a wide variety of materials. GPR is particularly appropriate for identifying the general arrangement of shallow buried objects as well as the internal elements of concrete, asphalt, stone and brick masonry structures.

Surveys are typically carried out by profiling the structure over a grid of survey lines which, following data analysis, provide a three dimensional reconstruction of the arrangement, form and condition of the scanned materials.

Half Cell Corrosion Assessments

A portable half-cell measures the corrosion potential in steel using a copper/copper sulfate reference electrode which measures signals sent through the reinforcement from a connection to an exposed part of the steel reinforcement.

The data is then mapped using a contour plot to visually represent the corrosion of an area (image).

Condition Assessments: Historic Construction

Building surveys include a NDE testing program that utilizes a variety of tools in conjunction with visual survey.

Surveys can be conducted on a variety of building types, both new construction and historic. Surveys can cover the interior or exterior building envelope or focus on specific features or issues, such as moisture infiltration, parapet walls and roofs.

Findings are then translated into drawings that can inform future repair design.

Low Voltage Leak Detection

Building surveys include a NDE testing program that utilizes a variety of tools in conjunction with visual survey.

Surveys can be conducted on a variety of building types, both new construction and historic. Surveys can cover the interior or exterior building envelope or focus on specific features or issues, such as moisture infiltration, parapet walls and roofs.

Findings are then translated into drawings that can inform future repair design.

Magnetic Particle Inspection

Magnetic Particle Inspection is an NDT method suitable for detecting cracks, near surface inclusions, seams, laps, and other discontinuities in ferrous-magnetic materials. By inducing a magnetic field onto the ferromagnetic material, surface cracks are able to be identified by clustering of magnetic particles.

MPI conforms to ASTM E709-14 Standard Guide for Magnetic Particle Testing.

Laser Scanning

A laser-scanner gathers raw survey data called a point cloud. A complete survey of the site will produce an accurate, measurable “cloud” of data points which can be queried for dimensional values.

Individual scans are then brought together into a single registered 3D database using scan targets which are measured and tied to survey control using a conventional total station.

Finally this data is used to generate 2D CAD line-work as architectural plans, sections, and elevations, and even more complex 3D Models.

Metal Detection

Metal detectors measure currents induced in ferromagnetic objects to determine their location. Metal detection is used to check for and verify any metal inclusions within the structure. Metal detectors are used as a complement to the radar data collected and are able to positively identify whether an object is metallic and / or ferrous.

A covermeter measure currents induced in ferromagnetic objects to determine their location. A covermeter is usually used as a complement to the radar data collected and is able to positively identify whether an object is metallic and / or ferrous.

Moisture Infiltration Survey

A specific NDE testing program can be devised to identify sources of moisture and extent of infiltration.

Techniques include

• RILEM Tube Adsorption testing
• Infrared Thermography
• Electrical Capacitance Testing
• Spray / Flood Testing
• Moisture Meter monitoring

Condition Assessments: Parapet Walls

Building surveys include a NDE testing program that utilizes a variety of tools in conjunction with visual survey.

Surveys can be conducted on a variety of building types, both new construction and historic. Surveys can cover the interior or exterior building envelope or focus on specific features or issues, such as moisture infiltration, parapet walls and roofs.

Findings are then translated into drawings that can inform future repair design.

Radio Detection

Electro-detection or radio detection detects free electromagnetic signal from buried metallic objects, and is typically used in the location of live or metallic services.

Photogrammetry

Photogrammetry is the process of generating geometric data from photographic images.

Orthophotography
GBG can provide orthophotos which eliminate all effects of perspective regardless of surface shape or orientation. These differ from rectified photographs in that each pixel of every photograph is effectively registered to a point in the laser scan data.

Rectified Photography
Multiple photographs are captured on site and are corrected for lens distortion before being registered to the laser scan survey data which removes perspective distortion relative to the plane of the main façade.

All of the individually registered and rectified images are then combined to form a composite rectified photograph of each building elevation which can be overlaid with 2D drawings to aid interpretation.

Condition Assessments: Roof Investigation

Building surveys include a NDE testing program that utilizes a variety of tools in conjunction with visual survey.

Surveys can be conducted on a variety of building types, both new construction and historic. Surveys can cover the interior or exterior building envelope or focus on specific features or issues, such as moisture infiltration, parapet walls and roofs.

Findings are then translated into drawings that can inform future repair design.

Seismic Evaluation

GBG works with architects, engineers and building owners to perform assessments of building construction, oftentimes identifying reinforcement arrangement in concrete structures ahead of seismic upgrade or for verification of code compliance.

These surveys are carried out using a combination of ground penetrating radar (GPR), metal detection and cover meters to determine extent, spacing depth of cover and diameter of reinforcement.

In other cases, GBG can identify variations in construction that may affect seismic performance such as changes in thickness or material type, defects such as cracks and voiding as well as locating formed voids such as utility chases and flues.

Spray & Flood Testing

Combined with targeted spray tests, thermography is used as a general investigative tool to identify the source, route, and extent of any moisture infiltration through the roof and walls. This combined approach minimizes the amount of water and dampness needed to identify a water path. The thermal output of the various surfaces is recorded in high-resolution, still, thermographic images.

Changes in temperature identified through the use of thermography can be directly attributed to conditions such as elevated moisture levels (dampness), delaminating plasterwork / masonry, and voiding.

Infrared Thermography (IRT)

Operating in the long wave to far infrared region of the electromagnetic spectrum, thermal imaging cameras allow an assessment to be made of minute temperature differences and changes.

Analysis of thermal difference allows for the identification of possible mechanical deterioration, variations in thicknesses of walls, and the development of spalls.

UPV

Ultrasonic Pulse Velocity measurements of a material are taken to assess the mechanical properties of materials such as strength, integrity and crack depth.