We are pouring a bike path near the Poudre River. We started noticing cracks on the surface running perpendicular with the broom finish. The concrete provider said it was surface cracks. But, when the owner took a core sample, the cracks went all the way through the concrete. Any suggestions on what might be causing the concrete to crack?

What slump was the concrete placed at. When did it crack at time of placement or next day. It sounds like shrinkage cracks. Was the wind blowing or not. Did you place it on ABC or native soil.

We have requested 4" slump but it has been showing up at 2-2.5 consistantly. We have had to add 20 gal. every 11 cy truck. It cracked right after and sometimes before we broomed it. The wind was blowing when we were pouring the first time we noticed the cracks. We thought that might be the problem. But the concrete still cracked on days that did not even have a breeze. It seems like some cracks occured with a particular truck because out of all the trucks (3-5 trucks) poured in one day there are long sections that did not crack and sections that did crack. The concrete is placed on native soil.

Did you cure the concrete- tell me more about the weather conditions- is there compactaion tests performed?
Did you use any fiber? what kind of joint pattern do you have?

DO YOU HAVE ANY EXPERIENCE WITH CONCRETE?
WHAT YOU NEED TO DO INSTEAD OF ADDING 20 GALLONS OF WATER IS ADD A PLASTISIZER !!!!
THIS WILL WET UP YOUR CONCRETE WITHOUT ADDING WATER, WHICE WILL NOT EVENTUALLY EVAPORATE AND CAUSE SHRINKAGE CRACKS./ GET A FRIKKIN' CLUE IDIOT!

This guy is a genius! Sounds like you have more "cents" than brains. If I order concrete at a 4" slump I expect it to show up close to that slump not have to pay the concrete company more to fix their mistake or negligence in this case.

I don't claim to be an expert, but how long are you waiting from the time you add the extra water until you pour? It takes 70 drum revolutions to mix that stuff up, so maybe its not mixed as thoroughly as it could be.

Then again, I just started in this industry, so I could be talking out my backside.

i think i was just a problem with the cement on the truck being to hot when you pour it.

The cracking you describe is classic plastic-shrinkage cracking, which comes from a combination of temperature, relative humidity, and wind speed. This can be minimized in future by using AR glass fibers at 1#/c.y. in the concrete, using Confilm during placement, and/or mist sprays or wind breaks.

We pour an average 150 yrds per day on sidewalk and have been struggling with the redi-mix company for the last two summers due to cracking. Sometimes its the load in the middle of the day. We have tried all of the mention fixes including different types of sealers. Through rumours we have learned there is a cement issue. The redi-mix company gets several different types of Chinese cement but will never admit they have a problem. Very frustrating. I wish someone could fiqure this out.