Saturday, September 21, 2013

Sunday, May 5, 2013

Investigation With Impact Echo

When investigating defects and deficiencies in concrete you need all the information you can gather.

It would be a nice benefit if you could just drill and extract core samples from every part of your element.  Pull 50-100-500 cores from every corner; a thousand would be even better.  No matter the time it would take.  Although this task would be immensely beneficial, it would be ridiculous to "swiss cheese" the member and an extremely an unlikely option anyway.  But consider this...

With Impact Echo, Tecvac, Inc. can produce a color coded grid map depicting the condition of 20,000sf of concrete, with simulated core extractions 5'o.c., in just three days.

Impact Echo Technology utilizes an extremely advanced method of non-destructive testing that will provide the necessary background data for assistance in making the right decisions to prepare an optimum repair strategy.  Here are just a few of the common applications Tecvac technicians have performed:

  • Delamination surveys of fascia tile tunnel walls
  • Sandwiched membrane integrity
  • Internal crack, void and honeycombing 
  • Surface opening crack depth measurement
  • Debonding of topping slabs
  • Slab thickness measurement
  • Injection repair quality
  • Reinforcing debonding

The DOCtertm (Defect Orientation Confirmation Tester) introduces a short duration stress pulse into the test object by technical impact on the surface.  A compression wave then travels into the object and is reflected by internal defects or external boundaries.  The wave propagates back to the surface and again into the test object by which a transient resonance condition is set up as multiple reflections occur.  This information is picked up by a transducer placed close to the impact point, processed and presented in graphic form.

This is a core sample from a bridge member surveyed in Georgia.  Just a fine little crack, seemingly unimportant from a glance.  Technicians however, were receiving information graphs of something totally different.  Repeated shots at and near the crack produced the same is what they found through a confirmation core from that location:

Just beneath the surface was severe honeycombing attributable to poor consolidation.  At the rear end of the core there is a piece of embedded form wood.   

This condition would have been totally overlooked with an observational survey and recording.  Any repair proposed would have no doubt entailed a simple injection of the crack; which would have failed in a short period and caused a re-repair.  Impact Echo finds internal defects that cause surface defects; proper analysis leads to a proper repair. 

Each of our technicians are carefully trained in the use of Impact-Echo.  I was trained at Cornell University by the inventor over 20 years ago, when there were only two of these machines in the whole of the United States.  Our technicians performed the most extensive Impact-Echo survey ever performed in Taipei, Taiwan for the Dept. of Rapid Transit Systems on their MUTA Line.

If you want to get closer to the root of the problem...Call Tecvac, Inc.  We offer short notice world-wide service to support your efforts.

Office 703 742-9186  Toll Free 800 847-9324  


Wednesday, April 24, 2013

Debonded Topping Slabs and Delaminations

The conventional method of repairing debonding and delaminations is to remove and replace the defect.  Sometimes that can entail a huge problem for the installer or owner when its a bridge deck topping, or some other facility with a large amount of square yardage -like a parking garage.  Not only can the removal and replacement require a high degree of coordination efforts, the area most times has to be taken out of service which can severely impact revenue streams.

When the Washington Metropolitan Area Transit Authority was in the final stage of opening its Suitland Station, it discovered the 4" silica fume topping slab cast onto the structural slab, that was scheduled to receive a quarry tile finish, was spotted with a large number of delaminated areas.  Since the platform was demobilized of equipment, and was now a literal island, this condition posed a nightmare logistical problem to remove and replace the topping...and would severely impact the scheduled opening (revenue). Tecvac, Inc. identified and verifyably put back into composite some 4,500sf of delaminated topping in-situ using its exclusive TecBondtm Interface Permeation Process and allowed the finish tile work, and the opening, to proceed on schedule.

When heavy forklift equipment damaged/delaminated a 3" topping slab cast onto T- panels on a second story warehouse floor, the disruption necessary to commercial retail tenants below to accommodate any form of removal and replacement was foremost on the minds of the owner and the property manager.  At the very least, an R&R operation would necessitate vacating  the occupant tenant and all of the tenant businesses beneath the warehouse (125,000sf) to temporary off-site facilities.  Then, when the repair was complete, moving all the tenants back into their spaces.  A costly endeavor to say the least but, without some alternative, there was no choice; since the T-panel ceilings above the retail spaces would occasionally deposit concrete chunks on desks and equipment below.  Working at night, technicians identified (Impact Echo survey...more later on this non-destructive testing method) and verifyably re-bonded 35,000sf of delaminated area in just 20 days...independent pull tests broke in the substrate at over 200psi and the floor was verified safe with load testing.  Noteworthy, the operations did not necessitate the displacement of the occupant or a single tenant located below.

Tecvac, Inc. is a supplier of the TecBondtm Interface Permeation Process and other high quality advanced technology services to the concrete, masonry and stone repair industry.  Where revenue conservation and a quick turn-key repair is required, Call Tecvac, Inc. with your toughest problem.

Tecvac, Inc.
800 847-9324

Wednesday, April 3, 2013

Crack Injection Without Surface Defacement

A good number of cracks in concrete, masonry and stone pose no structural threat to the member or the structure.  However, the mere sight of a crack in an overhead beam or support column will send the general public into an uneasy nervousness.  The repair of these cracks with conventional epoxy pressure injection might result in a repaired crack, but unless the completed repair is painted or coated, the resulting esthetics are often far worse than the crack itself.

Pressure injection requires the crack to be sealed with a material, usually a paste epoxy, that will tenaciously bond to the surface of the member being injected.  This tenacity is a requirement to contain the pressures exerted on the repair resin introduced into the fracture.  Removal of this sealer epoxy is most often performed by grinding the material off the surface with a rotary grinder; and most often mars the surface in such a way the defacing leaves little doubt a repair has been performed.  The removal of the crack sealing material can be impossible on fluted panels, decorative concrete, statues and historic members.  Depending on the severity of the cracking, or the "in your face" location of the crack, the fracture often leaves designers with little choice but to do nothing, or remove and replace the member.  Tecvac, Inc. has two solutions for this delima: CleanSettm and CrackMasktm. (Please visit our website at

Repair of historic textured/aggregate concrete using CleanSettm.  After the repair is made, the proprietary setup materials just peel away. 

After restoring the fracture with CleanSettm, CrackMasktm was applied to the crack on the left.  Even close up, the repair and the original crack are hard to detect.

When there are cracks you need to repair and go away...choose Tecvac, Inc.'s exclusive CleanSettm and CrackMasktm Processes.

Tecvac, Inc.
800 847-9324