Concrete Cracks

Many years ago I was privileged to attend a world-renowned concrete construction seminar held in Dallas, Texas. Numerous topics were to be addressed and the recognized expert on high-rise concrete construction was the featured early morning opening speaker. This gentleman had been involved as a contractor in more high-rise concrete buildings, bigger and higher than anyone else in the world. All of us had been hyped; looked forward to and rolled out of bed early for what he had to say. Thousands from all parts of the world were in attendance. The room was packed. Per the advertisement our speaker would share his number one secret for effective installation of concrete. To say it bluntly, this was a big deal as we waited in baited anticipation to learn from the expert in the field.

Mr. Concrete stepped to the podium standing there in silence for several minutes. You would have thought he was nervous and had forgotten his topic. Then he scanned across the room and said confidently:

"CONCRETE CRACKS"

After which he stared at us for a few minutes in silence (the famous pregnant pause?), turned and sat down.

First we all glanced at each other as his statement sunk in. Then all stood to their feet in a thunderous applause as we grasped the magnitude of what this expert had said. In two words we had made crystal clear what many of us had been attempting for life times to understand. Was this it? Was the lecture over?

Recently I heard those same words again in a much different arena. As the buyer and builder were standing in the driveway in front of the garage the buyer said, "what are these cracks?" upon which the builder stated, "you know, concrete cracks and there is not much we can do to control it." I couldn't resist. The buyer employs me and my job is to educate him/her about the condition of their proposed new home. I am not there to close the sale or make the builders life easier. The builder was selling and needed to close and wasn't interested in these cracks becoming a problem. I can understand. I once was one. But now I'm on the other side of the fence and have a serous fiduciary responsibility to my client. The conversation went like this:

Did you finish this home in the winter? Yes
Was it really wet? Yes
Did you have great difficulty installing this driveway because of mud? Yes

He had fallen into my trap and took the bait.

Did you install the drywall in the bonus room over the garage after this driveway was poured? Yes
Did you stock the drywall through this window over the garage doors? Yes
Where did the boom truck sit? Pregnant Pause

The builder was caught red handed with his pants down and his face was scarlet as he walked to his truck and left without saying another word. Was he upset? You could say so. Did I do my job? I think so.

The boom truck was too heavy for the design of the driveway even before putting the outriggers out. The driveway was cracked at the outrigger position closest to the window. This is where the most stress was placed, maintained, bounced and vibrated while the material was off loaded through the window.

How did I know this? It's called experience. These were stress cracks radiating out from a central point where the stress was placed. All the rest was from simple conjecture and reasoning. The subbase of the driveway was inadequate. The driveway itself was over loaded and failed at the stress point.

Elementary my dear Watson, elementary.

Luckily for the builder the home closed, but he had to give an extended warranty on the driveway. Replacing poorly installed and/or damaged driveways cost three times what the original installation cost. The solution? The first person to drive on a driveway or in the garage should be the buyer after closing!

Back to Dallas:

Mr. Concrete rose back to his feet and walked to the podium. Another pregnant pause, this guy was good. "Gentlemen & Ladies (there were only a few in the room) the secret to effective concrete construction is this: Concrete cracks and only you have the power to control where it cracks. Control where it cracks and you are the best in the business. Fail and your reputation will fail along with your concrete." Having said this he stared at us again for a few minutes turned and walked down the center isle. As he left the room the crowd rose to it's feet again in a deafening applause.

The next seminar was "Crack Control" by the same speaker. Did this speaker make his point? You better believe it. In less than 10 minutes thousand left with a new appreciation for controlling cracks in concrete. We all attended the next session.

This is a lesson I have never forgotten from 15 years ago. As I inspect homes and commercial buildings the magnitude of cracks never ceases to amaze me. So many have failed to learn the 10-minute lesson. Telling clients that concrete cracks is not the answer to the issue. Knowing that concrete cracks and controlling where it cracks is.

It's refreshing once in awhile to walk on a site and view properly placed crack control joints and NO CRACKS. Is it possible? You can believe it. Does concrete crack? We all know it does. Do we have to live with those unsightly cracks? Absolutely not! Next time a builder tells you as you look at that crack. "You know, concrete cracks." You don't have to blurt it out, but in your mind, you can say: Yes, and it's clearly evident you haven't figured that out yet.

Rules for controlling concrete cracks:

Adequate properly prepared subbase
Proper weather, not to cold, not to hot, not windy
Adequate mix design
Properly placed crack control joints. Not more than twice the width or 15 feet apart which ever is less, full depth or not less that 1/3 the depth of the slab.
Proper curing: Though there are other ways (sealers, cover, ext.) the best remains wet curing for 7 days.
Keep all traffic off. The first person to make use of a driveway or garage should be the one buying it!
Last but not least: Keep vehicles and equipment heaver than the installation is designed for off of the slab forever. Nothing more than cars, motercycles and pickup trucks should ever drive on 4" of concrete and even they should never drive on or across a narrow walk.

Bonus:

Want to have a Lilly white finish on your exterior concrete? As soon as possible after the concrete is hardened, apply a sealer with a white color pigment in it. Such can be purchased from commercial material suppliers and is what is often used on street curb and gutter. For an added bonus, this helps protect the concrete from mud stains although you should make a great effort to keep mud off of all concrete.

Thought for the week

It has come to me as I get older that the most important issues to having a happy life are:
Living with a fine woman (man, significant other) and a good dog.
I know I have arrived! Where are you?