Concrete driveway loads 2

[Appraiser]

Assumption: A standard concrete slab mix is 3500 psi, has no reinforcement.<br>
Q: Could a heavy vehicle (13,000 lbs rear wheel axle rating)cause hairline cracking of a fresh (6 Month)driveway? Or would this more likely be attributed to a poor subbase?

 

[bb29510]

a hairline crack is not a structure crack but a crack cause by freezing and twaning of the concrete slab. Although it might not be cold where you are at the same principle applied to the drying of the orignal slab during placement. Curing compound during placement will help in this matter but if all goes correct during placement it is still very, very rare not to have a slab crack. this is why control joints are design. A subsoil failure would result in a crack of 1/16 to 1/4 almost overnight.<br>
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my brother parks his triaxle dump truck on a 2500 lb mix with no problem

 

[Ginger]

The main cause of structural cracking will be the sub base. The concrete will have sufficient strength to support the load without punching through and causing cracking. If however, your sub base has soft spots then the slab will attempt to span these softer areas and with no reinforcement present it will most probably crack.<br>
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If you have noticed a hairline (non-structural)crack in your concrete it will most probably be due to drying shrinkage. If you haven't divided the slab into bays with movement joints or used a slip membrane below then it will shrink over the first 6 months and tensile stresses will develop causing subsequent hairline cracking.<br>
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Regards<br>
<br>
Ginger

 

[Ron]

Most likely cause of hairline crack is drying shrinkage. Pattern and location of crack dictated by joint pattern, differential thickness, subgrade restraint and concrete properties. Likely has nothing to do with freeze/thaw.

 

[daski]

If I had a dollar for every time I've been called out to a site to look at cracks in floor slabs.... <p> <br><a href=mailto:markdaski@aol.com>markdaski@aol.com</a><br><a href= > </a><br>

 

[Appraiser]

Thank you all for your input on the above subject. ........Appraiser

 

[merbas]

Dear engineers,<br>
I would like to explain driveways reinforcement again.<br>
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In a slab you can face to two possible cracks: Structural and Non-structural.<br>
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If you do not design correctly the thickness and other parameters as joint spaces or subbase movement cause structural cracks in the slabs.<br>
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I did not design any slabs but, casted millions of sqm at the job sites.<br>
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If you believe my experience I will share my pratical information at next mail.<br>
<br>
Please just have a look the coming notification.