"If you are not Testing, you are Guessing” (On how to Properly Repair or Restore your Concrete Structure)

Over the past 30 plus years in the concrete repair and waterproofing materials business the materials have evolved, got safer to use, have longer warranty's and are better than ever before. During these past 30 years being a member for ICRI (International Concrete Repair Institute) and IIBEC (International Institute of Building Enclosure Consultants formerly RCI, Roofing Consultants Institute) has helped to keep building consultants and technical product rep up to date with the latest technologies to repair, waterproof and extend the service life of these structures for their owners. Here is a list of some of these items that have been introduced in Hawaii during this time period.

Polymer modified concrete repair materials

Breathable, waterproof, elastomeric coatings

FRP rebar

Corrosion inhibiting admixtures and repair mortars

Corrosion resistant rebar coating and primers for spall repair

Fluid applied silicone roof coatings

Fluid applied urethane roof coatings

45-minute cure times on fast setting repair mortars for vehicle traffic

CFRP and GFRP external concrete strengthening (carbon fiber reinforced polymer & glass fiber reinforced polymer)

BFRP (basalt filament fiber reinforced polymer) rebar that is stronger than and cost less than steel

2 hour fire resistant, water resistant, insulating, one coat stucco @ 1" application with 24 cure time

Also, during this time period, as a technical product rep for a number of these products that have been introduced in Hawaii and I have assisted with the design and use of these technologies with engineers, architects, consultants and building owners.

When asked for assistance with the repair or restoration of a building or structure the first thing needed is any documented history of the structure such as original plans and specifications. Hopefully as-built-drawings from the original construction and then a current building envelop survey. If none of these documents are available, then you start with a thorough building envelop survey with photos and measurement documentations, (the BLK3D from Leica Geosystems can be a great tool for this, https://shop.leica-geosystems.com/buy/blk3d/blk3d#oid=137390_3197) at a minimum but, preferably with testing.

A number of years ago from Dick Elsner, a professor at UH Manoa and one of the named principles in the national building envelop and consulting firm Wiss Janey Elsner aka WJE, "If you're not testing you're guessing" on how to repair and waterproof a structure. Dick was right because I never have met anyone who can give me quantitative test data regarding a number of factors regarding their building or structure from just looking at it.

Think of seeing a building envelop consultant as would going to see your doctor or dentist. When you are seeing your doctor or dentist and they will always ask "How are you doing today and is there anything that you're concerned with or the hurts?" Well, if the answer is yes and the area that hurts or is sore is not visible on the surface of your body the doctor or dentist will usually order X-Rays, MRI and or blood tests to better know what is going on inside you so they can make good diagnosis and course of action with options on how they can fix what is ailing or hurting you. Same goes for your building or structure and your building envelop consultant. Sure, it has leaks, and sure it has spalls but, was is the root cause of why this happening? That's what testing can tell you?

Testing lets the consultant prepare various options of repair based on the building owner's budget and immediate needs. Here are a few examples of what testing can tell you.

Water testing can be as simple as spraying a hose and charting leaks to very sophisticated spray racks that document where the leaks are and at what pressure do they leak and the how many ounces or gallons per minute or per hour they leak at. If water is getting into your steel reinforced concrete structure corrosion, cracks, spalling and eventual concrete and structure failure are immanent if not corrected. Water testing can also include IR scans and moisture detection scans to map moisture within roofs and walls. So, leak detection and water testing should always be the first part of ones building envelop survey after visual and photo documentation. There are 10 or more ASTM Standards for Leak Detection Testing and the correct one to use depends on existing conditions and structures size.

Next test to be considered for your concrete structure is pH testing. ASTM F710, Standard prep for concrete floors to receive resilient flooring includes pH testing. Healthy concrete is concrete high in ph. New concrete is highly alkaline and when reinforcing steel is in an alkaline environment with a ph. 12 or higher the steel in that concrete will not corrode or would corrode at a very slow rate. Once ph. level drop below 10 corrosion is immanent. Carbon Dioxide is a reason for the drop in pH in concrete. There are coatings that are elastomeric, breathable, waterproof and provide a carbon dioxide screen which will help concrete structure maintain a high pH.

Are there chlorides in your concrete? ASTM C1218 Standard Test Method for Water Soluble Chlorides in Concrete and Mortars is the test method that should be done for any major concrete repair project. Chlorides are salts that when made fluid with water intrusion/leaks accelerate the rate of corrosion of reinforcing steel in concrete. When reinforcing steel corrodes, it expands at a force much greater than the tensile strength of the concrete (concrete is very strong in compression or standing on it but weak in tension puling or expanding within it) causing the concrete to first crack and then if not repaired will continue to expand and then spall (a spall or spalling is when chucks of concrete falling off or becoming dis-bonded from a concrete structure usually do to reinforcing steel corrosion). Knowing the chloride levels is critical because if the chloride levels are above 6.5 pounds of chlorides per cubic yard of concrete there is no repair mortar or concrete with or without corrosion inhibitor that will work or last any length of time. When chloride levels are that high and they do get that high and much higher here in Hawaii. 

Here are a couple of examples as to how testing was used to make repair recommendations and options for some well known Hawaii projects.

The Turtle Bay Hotel on the North Shore of Oahu built in the late 60s and opened in the early 70s. During a change of ownership in the late 90s/2000 the hotel structure was severely damaged for corrosion with spalls all over and some dangerous lanai and railing conditions. Because the chloride levels were so high 8 to 20 pounds per cubic yard, the lanai's needed to be cut off and removed. New lanai's pre-cast concrete lanai's were made with corrosion inhibiting admixture and re-installed on ledger blocks and grouted in-place as to not to connect the new steel in these lanai's to the older corroding steel still in the adjacent walls. These lanai's are still in use almost 20 years later.

Another example would be the Natatorium in Waikiki. Back in the late 90's it was falling apart and the decorative cast sculpture's atop the walls were spalling along with the rest of the place but, the project was to make it safe to enter and use the restrooms which meant the decorative items had to be restored as this is a historic structure. The sculptures were taken down and rubber molds were cast over the sculptures which include detailed Eagle's heads. Testing, ph. & chloride, told us there was no saving these and that is why FRP rebar within the sculptures and new corrosion inhibiting repair mortars and grouts were used for the spall repair of the concrete. The Natatorium restrooms are is still in service but, the City needs to decide what is to be done with this structure as it does continue to decay on the bleacher and pool side of the structure.

Aloha Tower, another historical site had a thorough visual survey and physical sounding of the surface to determine where the corrosion and spalls were. Because all repairs were done to ICRI repair standards and some of the best polymer modified mortars were used and this is another structure coming up on 25+ years since it's late major restoration. Bosyn chairs were used to access all areas of the towers surface.

So, who does concrete testing and analysis in Hawaii? There are few local materials testing labs locally here in Hawaii. Most good consulting firms will do double blind testing taking 2 samples at a minimum from specific areas of a building and send one to a local lab and one to a larger mainland lab for comparison. This was the process used at Turtle Bay and other projects we've been involved with.

The future of concrete reinforcement is going to be FRP rebar and products. The advancements if FRP rebar products and the different types of fibers offer more options than ever before.  With the advancement is manufacturing with GFRP and BFRP that can be produced at well over 200 linear feet per minute means FRP reinforcement that cost less than steel and being an FRP it will never corrode.

Currently, #3 BFRP GatorBar rebar is approved by the City and County of Honolulu for curb, gutter, sidewalks and concrete paving on C&C projects and will be approved when designed into project by a licensed engineer or architect for their projects. As more sizes of BFRP rebar become available and more testing and State specifications will come out for the use FRP and specifically BFRP and GRFP rebar will become a standard and commodity just like steel is now. The Florida DOT has released their FRP specifications for bridge and highway work there just like Canada DOT did in 2015 after 8 year testing of FRP reinforcement in the bridge toppings. It should be note that steel rebar does not have near the testing that FRP rebar has. FRP rebar has been held to a higher standard because it is new (actually been around over 30 years now) and engineers have been designing with reinforcing steel for over 100 years. It is funny how engineers are slow to change from steel to FRP but they are constantly upgrade equipment

Building surveys and testing are the best way to know exactly what is needed to repair a structure and provide an owner with various options of repair based on service life and budget.

Paul K. Kane, CSI, CDT

Paul is the owner of Aloha Marketing and has a 30 plus year career as a technical building material and product sales representative advising consultants, architects and engineers in Hawaii and the West Coast. Paul is the "Consultants consultant" here in Hawaii and is active in the Construction Specifications Institute, with his certification as a Construction Document Technologist and International Concrete Repair Institute Concrete Repair & Waterproofing Specialist, the Building Industry Association of Hawaii and the National Association of Home Builders, Mason Contractors Association of Hawaii and the Hawaii Walls and Ceilings Industry Association. Paul's building materials and product career started in a concrete products testing lab learning about cement chemistry and the manufacturing and testing of concrete, mortars, grouts and the ASTM testing of these products to assure they far exceed the ASTM minimum standards.

Most recently Paul has worked as the Construction Services Administrator for the Bergeman Group a regional building restoration consulting firm based here in Hawaii.