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Cracking Up Not a Laughing Matter By Drew Robb

Concrete cracks. That’s a fact of life. Some cracks might not need attention, while others could have serious struc-

tural consequences. But how can you tell the difference? Much of the time you can’t, and expert advice is required. “It’s important to accurately assess structural cracks to deter-

mine what is significant and what is not,” said John Duntemann, a Principal at consulting engineering firmWiss, Janney, ElstnerAsso- ciates (WJE). “You have to properly identify the extent and cause of cracking before you can implement the right repair solution.” Cracks in concrete might be caused by a number of factors,

such as thermal expansion and contraction, sub-grade settle- ment, the loads being applied, and even earthquakes. This all adds up to internal and external stress that manifests as big and small cracks. Parking garages, stadiums, airports and other structures

heavily reliant on concrete are subject to cracking due to heavy loads, vibration, and temperature and weather shifts. Garages, for instance, are subject to concrete cracking because of not only applied load, but also structural movement due to ther- mal changes. All require vigilance when it comes to cracking and structur-

al integrity. In many cases, however, there is uncertainty as to what to do about cracks. Pete Barlow, a Principal at Contech Services, which

repairs, strengthens and waterproofs concrete structures, said his company is constantly being contacted by anxious building man- agers and owners. “Many times a week, people send us photos of cracking at their facilities, asking for advice,” Barlow said.

Crack Classification There are various methods of classifying cracks in concrete.

One primary way is to split them into two groups: structural and non-structural. Structural cracking affects the integrity of the building.

Cracking in support beams, columns and load-bearing areas is of particular concern. Non-structural cracks, on the other hand, are not detrimental

to building integrity, though they may need to be addressed due to cosmetic reasons or to take proactive steps to prevent those cracks from growing over time and eventually reaching the struc- tural stage. Tiny fractures also can lead to other challenges. “Small cracks in below-grade foundation walls can allow

water to migrate into the structure,” Barlow said. Size of the gap is another consideration. Hairline cracks are

generally not a problem, but it depends on where they are.Ahigh frequency of them, though, could indicate an underlying stress issue that needs to be addressed.

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