Guide to 3D Laser Scanning for Concrete Construction

Guide to 3D Laser Scanning for Concrete Construction

A GPRS/TruePoint laser scan.
A concrete ramp under construction
Rebar and conduits laid out in preparation for a concrete pour

Leveraging 3D Laser Scanning for Concrete Analysis

Assessing concrete has previously relied on inherently unreliable methods for gathering information.

The advent of 3D laser scanning has allowed contractors, inspectors, and designers to easily identify issues and reduce errors with millimeter-accurate data. Dimensional and tolerance assessments can be completed quickly to prevent costly project rework. 

The current method for assessing concrete requires manual inspection and contact-type measurement devices, which are time consuming. The process for gathering information is prone to human error, documenting the information is tedious, and the platform to communicate is informal.  

3D laser scan technology is transforming the way contractors document and assess concrete projects. It can measure floor flatness and floor levelness, scan wet concrete, scan pre-pour and post-pour, check tolerances and deflection, perform MEP and construction verification, assess structural concrete, prefabricate stairs and railings, inspect for ADA compliance, survey parking garages, assess concrete stairs, laser scan ground penetrating radar (GPR), and more.

GPRS 3D Laser Scanning's cutting-edge 3D laser scanning services can help eliminate the headaches associated with the old ways of performing all these tasks.


3D Laser Scanning to Assess Concrete

What once took days to accomplish can now be completed within a matter of hours thanks to 3D laser scanning, which provides far more accurate data and better information than the old, manual assessment process.

3D laser scanners capture highly-accurate digital representations of project sites in 3-dimensional x, y, and z coordinates in the form of a point cloud. Scanners are self-leveling, positioned on a tripod, and set up around the perimeter of the construction site; they will not interfere with work in progress. Data is collected from a distance without physically touching the site. Site data can be analyzed virtually, and adjustments can be made to fix problems immediately. 


Applications for 3D Laser Scanning Concrete

A floor flatness and floor levelness evaluation by 3D laser scanning.

Floor Flatness and Floor Levelness

Without 3D laser scanning, floor flatness/floor levelness (FF/FL) analysis typically relies on manual and labor-intensive methods. A commonly used method involves creating a grid on a concrete slab following a set of specifications before taking manual readings. Contractors that use the ASTM E1155 standard method for determining floor flatness (FF) and floor levelness (FL) numbers typically take a measurement every foot along the grid lines. Using this method, even small projects require a substantial amount of time to complete data collection. 
3D laser scanning quickly captures highly-detailed point cloud data to determine FF and FL values on concrete floor/flatwork, saving both time and money. Color elevation maps can be quickly produced from the point cloud data to visualize floor flatness and identify the high and low points in concrete and calculate the boundaries of any areas that need to be adjusted. The data points collected maintain their coordinates and can be easily communicated to the project team. Fast and accurate cut/fill calculations can easily be computed. Contractors can fix elevation discrepancies with speed and assurance.
Laser scanning produces a colorized elevation map of the entire floor. This way if questions arise, stakeholders can be educated on the standards and the project is validated with data. 3D laser scanning can protect the concrete contractor and eliminate disputes.

A worker marks out subsurface obstructions on a concrete floor.

Wet Concrete Scan

Laser scan technology is uniquely capable of identifying high or low spots while the concrete is still in a working state. The technology is non-contact, providing accurate data from a distance. It can follow crews from pour to pour, quickly producing heat maps, allowing the contractors to make immediate corrections while the concrete is still soft. The difference between being able to fix a problem while the slab is still workable compared after its set is likely tens of thousands of dollars in repair costs.

A worker evaluates a concrete slab.

Concrete Pre-Pour and Post-Pour

Contractors use 3D laser scan data to demonstrate that the assets exist per the engineering drawings, giving complete documentation pre-pour of the assets from the start. Laser scanning captures the finished pour with millimeter accuracy to ensure the pour was compliant with the design. The slab can be laser scanned again once it has met strength targets, completed post tensioning, and all temporary shoring is removed, providing the true deformation of the structure.

Two workers scan a concrete slab in a construction site.

Scanning for Tolerances

Laser scanning is rapidly being adopted to check tolerances, providing quantitative data to contractors, inspectors, and designers. Contractors will know if concrete floors, walls, stairs, ramps, and columns are out of tolerance. Scans can be performed multiple times in the same area while construction proceeds. A contractor can scan before reinforcement is placed, when the steel has been positioned, shortly after concrete placement, and after shores have been removed. The location of all steel, the thickness of the slab, and tolerance information can be retained for internal use or in the event a dispute arises, or it can be sent to the project owner.

GPRS team members conduct 3D laser scan equipment.

Scanning for Deflecting

3D laser scanning can measure concrete slab structural cracks and deflection, which can occur over time due to variables such as settling, shrinkage, fatigue, design errors, aging, point loads, and/or damage. 
3D laser scanning can also check the status of steel beams before and after concrete pouring to uncover any deflection that may be occurring. 
Detailed information about existing site conditions is documented in a point cloud, and accurate to within millimeters. 2D drawings and 3D models can be created to document deflection and design a plan to correct it.

A 3D laser scanner is positioned within conduit prepared for a concrete slab pour.

Verifying MEP Concrete Work

3D laser scanning provides the ultimate solution for verifying mechanical, electrical and plumbing (MEP) concrete work right in the field. You can ensure all conduit, rebar, and embedded sleeves are in their proper place, visualize and immediately identify problem areas, and communicate this information back to the field crew and office using the documentation generated from the scans. Once the concrete is poured, nothing can be changed. 3D laser scanning is a powerful tool to help monitor a project site to make sure everything is ready for a concrete pour. There is no need to risk discovering a problem when it is hard to go back. Data collected will be an asset for years to come, as it can be referenced for any future coring or drilling needs, showing where everything was embedded in the slab prior to pouring.

A 3D laser scanner is positioned outside a multi-story building.

Construction Verification

3D laser scanning is the fastest method for locating potential risks, allowing for the capture of real-time, as-built verification directly at the job site. This technology can compare scans against the as-built drawings or model, detect incorrect placements and fix errors quickly, and monitor shifts or changes in the building over time. Contractors and engineers can ensure their design plans are accurate and eliminate clashes before they turn into change orders.

Interior of a concrete structure.

Structural Assessment of Concrete

3D laser scanning can assess and document the floors, ceiling slabs, walls, and columns of reinforced concrete buildings. This can be done to create as-builts or identify structural defects. The spatial information of the point cloud helps make decisions based on accurate data. Identifying defects of components and completing virtual design planning to remedy them will minimize rework costs.

12.	A 3D laser scanner positioned in a stairwell.

Prefabrication of Stairs and Railing Systems

Existing structural elements like staircases, walkways, and railing systems can be scanned for prefabrication and modification. All necessary measurements are captured and transformed into 3D BIM models, 3D mesh models, or 2D CAD drawings for better project planning, ensuring accuracy with little to no rework. Data ensures elements are prefabricated to the right specifications and expedites installation

A concrete ramp under construction

Inspecting Ramps and Cross Slopes for ADA Compliance

The Americans with Disabilities Act (ADA) of 1990 prohibits discrimination based on disability. Curb ramps must meet specific standards for width, slope, cross slope, placement, and other features to comply with ADA requirements. 3D laser scanning allows for thorough inspection of ramp and cross slopes for compliance with ADA requirements. The current methods used to inspect ramp and cross slopes include manual tape measures and levels – options that are unreliable and time-consuming. Laser scanning documents ramps and cross slopes with 2-4mm accuracy in minutes. Point cloud data can be delivered quickly, or 2D drawings and 3D models can be created for site evaluation. Data allows contractors or engineers to virtually see the site and obtain measurements for redesign, if required.

A worker evaluates a concrete slab.

Inspecting Parking Garages

There are multiple applications for 3D laser scanning technology when it comes to inspecting parking garages, including estimating clearances, measuring slab thickness, measuring the thickness and depth of beams, and assessing ramps. The point cloud data collected can be used to generate architectural drawings, elevation views, color elevation maps, and 3D models for contractors.

A worker evaluates a concrete slab.

Assess Concrete Stairs

Concrete stair dimensions and step construction details are easily documented with 3D laser scanning, whether the purpose is for recording repair work or construction defect litigation. Tread height and depth can be compared to building code specifications. Data can be received in point cloud format, 2D CAD elevations and 3D models.

A handheld ground penetrating radar scanner.

3D Laser Scanning GPR

Ground penetrating radar (GPR) accurately documents underground utilities, rebar, and post-tension cables located within or under concrete. 3D laser scanning can capture those GPR markings to accurately document everything found using GPR. 3D models and 2D site plans can be created to eliminate potential problems during construction and improve safety before cutting or drilling into the concrete.

In Conclusion

3D Laser scanning provides a complete digital documentation of any structure – top to bottom; slabs to columns; before, during, and after construction. It provides reliable dimensional data and quality assessments of concrete in a fraction of the time it takes with manual measurements. It’s the most reliable tool for checking the conformity of concrete levelness, dimensions and tolerances to prevent rework or failure during construction.

For more information on 3D laser scanning for concrete construction and analysis, contact GPRS 3D Laser Scanning today by requesting a quote or scheduling a service!

GPRS 3D Laser Scanning services can measure floor flatness and floor levelness, scan wet concrete, scan pre-pour and post-pour, check tolerances and deflection, perform MEP and construction verification, assess structural concrete, prefabricate stairs and railings, inspect for ADA compliance, survey parking garages, assess concrete stairs, laser scan GPR and more.