Robert Lamoureux | Concerns about ‘exploding’ concrete

Robert Lamoureux
Robert Lamoureux

Question No. 1 

Hi Robert, 

I am in Canyon Country. We had concrete poured on our driveway less than a year ago and there are many cracks, which the contractor says are normal, but there is also the issue of the concrete “exploding” from the top. There are four different areas where this issue is about a quarter-inch thick, and is becoming more and more unsightly. There is also an area where the cracking is happening in a circular pattern, which the contractor is also saying is normal. Can you please look at the photos I’ve attached and tell me if this is in fact, normal, or if something can be done? 


Sometimes when concrete is poured in the intense heat of the summer, contractors will dilute the mix to keep it wetter during pouring. This can cause integrity issues if it’s not done properly. Courtesy photo

Answer No. 1 


Absolutely not. This condition, the “exploding” you are referring to, is called spalling and no, this should not be happening on new concrete. 

Minor spider cracks will almost always happen but these, especially the circular pattern and in conjunction with the spalling, tell me there is an issue with the mix used. 

Sometimes when concrete is poured in the intense heat of the summer, contractors will dilute the mix to keep it wetter during pouring and setting. 

This is only OK up to a certain point, but then the mix loses its integrity and issues like this appear later. With the added water, it is easier to control the finish during the pour and float, but that water eventually evaporates and the actual concrete/mix is what is left. If it has been diluted, then you are now left with what remains and that is less concrete “crème” on the top, and less of a bond in total. 

This is where the spalling begins. The concrete doesn’t have the strength to withstand the use or weather, and starts to crack and break apart. 

Like I said earlier, you’ll always see some hairline cracking, but to this extent and in the circular pattern plus the spalling, tells me that your contractor just did a poor job. 

Hopefully you used someone licensed and insured, and if given the opportunity they’ll make it right. Give them a chance first to rectify this and hopefully you won’t have to move legally against them. 

This most certainly, though, should be redone. Beware, a poor contractor may suggest “filling” those areas. I would absolutely not allow this. It is only a Band-Aid and you’ll be back in the same position in a short amount of time. This needs to be demo and redone, properly. 

Good luck to you. 


Robert Lamoureux has more than 40 years of experience as a general contractor, with separate licenses in electrical and plumbing contracting. He owns IMS Construction Inc. in Valencia. His opinions are his own, not necessarily those of The Signal. Opinions expressed in this column are not meant to replace the recommendations of a qualified contractor after that contractor has made a thorough visual inspection. Email questions to Robert at [email protected].

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