Vijay Posted February 27, 2018 Share Posted February 27, 2018 Got the first delivery of concrete B&B floor beams today and one has multiple hairline cracks (which the haulage driver very quickly pointed out before he made any attempt to offload) and another has one hairline crack up one side. How worried should I be about hairline cracks? Cheers Vijay Link to comment Share on other sites More sharing options...
jpinthehouse Posted February 27, 2018 Share Posted February 27, 2018 I would be taking a picture and contacting the b&b manufacturer and also check the rest John Link to comment Share on other sites More sharing options...
Vijay Posted February 27, 2018 Author Share Posted February 27, 2018 That's my exact plan but was more concerned that they just say it's fine and it's not Link to comment Share on other sites More sharing options...
jack Posted February 27, 2018 Share Posted February 27, 2018 Concrete can develop fine surface cracks depending on various factors during curing. They don't affect strength, as I understand it. Whether this is what you have I don't know, sorry. Definitely one for the supplier Link to comment Share on other sites More sharing options...
bissoejosh Posted February 27, 2018 Share Posted February 27, 2018 (edited) Definitely worth checking, if they've been loaded/stacked or handled incorrectly they could have been damaged. I was told by our supplier that the beams can't handle very much unsupported overhang and if picked up incorrectly they can crack really easily. Edited February 27, 2018 by bissoejosh bad quote Link to comment Share on other sites More sharing options...
Vijay Posted March 11, 2018 Author Share Posted March 11, 2018 Just to update, the supplier are swapping the hairline cracked ones, even the one with a single hairline crack. Link to comment Share on other sites More sharing options...
Nickfromwales Posted March 12, 2018 Share Posted March 12, 2018 Thanks for updating . Link to comment Share on other sites More sharing options...
StructuralEngineer Posted March 12, 2018 Share Posted March 12, 2018 The beams on beam-and-block are cast in the factory, and should therefore be quality controlled. The reinforcement bars they put into the beams are pre-tensioned, which means that they are pulled at each end before the concrete is cast around them. Once the concrete has set, the tensioners are released and the bars cut off flush with the ends of the beams. What this does is compresses the concrete because the bars are trying to regain their original (shorter) length. So the short answer is that you absolutely shouldn't have any cracks in the beams, and if you have, something's gone wrong in the factory. Also the driver's explanation doesn't stack up, since the concrete used is extremely strong. 2 Link to comment Share on other sites More sharing options...
jamiehamy Posted March 12, 2018 Share Posted March 12, 2018 That was a good result, even if it shouldn't have happened in the first place. Bit of a pain if you have/had the next stages ready to go. Thanks for explanation @StructuralEngineer Link to comment Share on other sites More sharing options...
Vijay Posted March 12, 2018 Author Share Posted March 12, 2018 The driver was from an external haulage company, so only there to transport what he's asked. I think he just wanted to point it out rather than pass any blame Link to comment Share on other sites More sharing options...
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