This is the problem we had, only with their i-m 1 mix a blended cement with pfa.All of the others(a few hundred)no problem.at least five contractors near to me have had surface issues,all used Lafarge concrete/products!!!!!
I have just got back from a round trip to Glasgow to inspect a driveway that I laid summer last year. The job has delaminated and crumbled like I have never seen in 25 years of the business.
I have to dig it all out and relay the job.
Lafarge supplied the ready mixed concrete a blended mix.
I have laid blended mixes half of my life from both Lafarge & Cemex but this is a major problem and very worrying.
Something has been changed with the mix design because Larfarge readymix used to be able to stand the frost and I have hundreds of driveways to prove it.
I have also noticed an increase of bleed water not only with Lafarge but other readymix companies this tends to suggest OPC has changed across the board. This driveway in Glasgow we had a problem with bleed water half way through the job and it is this area that has failed the first couple of loads is fine.
The temperature dropped to -20 up there this winter.
As for the problem, I do hope Lafarge will hold their hand up to the problem and pay me to reinstall the job.
I have used blended mixes with pfa no problem in the past. I rang the company overseas that supplied the admixture many years ago and was told OK.
Not all admixtures are compatible with Fly Ash and does stop the air working as i-w says.
Something must have been changed in between our mixes, possibly the admixture.
Hi guys, I havent been on here for yonks, But need to join in on this topic, We have had alot of this down in the southeast too. I have a very good explanation to the problem and why its happened. Its very late tho now so will come back to you guys very soon with my veiws.
we have had this problem and it seems to be all our jobs that used a blended cement(pfa),this prevents the aea from working correctly. also excessive amounts of lignite.who supplied your concrete?
One cause of delamination of colour hardener is trapped bleed water. Bull float before it appears and dont apply colour hardener until its gone. If you do the surface is weaker and freeze thaw cycles can cause the weakened surface to delaminate.
As we all know sealers are without doubt the one main areas of contention with PIC. There are so many variables that can effect who the sealers perform and weather conditions are a huge part of this. To Hot, To Cold, To Wet, and believe it or not concrete can even be to dry to seal...!!!!
I think DHD has raise a good point regarding moisture vapour transmitting through the slab. Over the past few years we have experienced longer periods of wet weather and floods, hence more chance of this becoming an issue.
Good concrete construction practice would be to use a damp proof membrane when possible, remember that these are actually a vapour retarder and not a complete barrier.
Another serious condition is SALT, this is by far the worst enemy of concrete and salt erosion in concrete can last for months and in some cases years if not cleaned and treated. Salt also breaks down sealers over time so I would suggest you tell home owners to clean their drives on a regular basis during the cold winters and longer exposure to salts.
just a thought could the sealer manufacturer have changed the formula of the resin, could there be more moisture transmission from the sub base through the slab .i think this year were going to lay every job on plastic to minimise this.
I re sealed a drive last summer with no problems at all.
I got a call last week to say his drive has started to go white...
I went yesterday to have a look and sure enough there is a faint white bloom right down the centre of the drive. Now any ideas why that would happen LOL
Answers on a post card please. The winner can reseal the job LOL.
