What the hell is 6F2?!
It’s a been a bit of a crazy week, and it’s all P C Harrington’s fault! So much has happened it’s difficult to pick one thing to chat about.
I could talk about this…
I could talk about this…
But instead I’m going to talk about fill.
After the nightmare of the sinking crane on Tuesday (see above), I have been keeping a keen eye on the construction of the mobile crane base for the construction of our second tower crane (we have 5 in total!). The base is to be 450mm thick. Laid in 4 layers. Each compacted with 3 passes of the roller onsite.
First of all they laid it far too thick. Then they didn’t realise that a roller is categorised by its mass per metre width. These things are forgivable. What followed is not…
About two months ago I was halfway through Rhubarb Creek writing about how the 6F2 would be compacted by a certain number of passes of a vibratory roller. At that point I didn’t really understand what 6F2 was (sorry Richard!), but now I do. It is a granular fill with a very specific grading curve. It is not:
So I explained this to them. They said they would pick out the bits, compact and make sure it didn’t happen again. This morning I found this:
![IMG_0720[1]](https://pewpetblog.com/wp-content/uploads/2015/02/img_07201.jpg)
![IMG_0717[1]](https://pewpetblog.com/wp-content/uploads/2015/02/img_07171.jpg)
Plastic Wood
Now while this is fairly funny and a bit annoying for the bloke who is picking all the crap out of it, it’s not great for the company. They’re paying for 6F2 and they’re not getting it. The quality assurance process they should have in place they don’t.
So we’re working with a company who are running late already (we’re only 2 weeks in), they’ve already had an accident (see tipper above), and their workmanship is shoddy (see last weeks blog). They’ve got a bad enough name here as it is, so why are they accepting this? Probably the same reason why we hired them in the first place. The fill is like the company, a bit crap but bloody cheap!
At the end of my second week I have learnt an important lesson:
IT’S ALL ABOUT MONEY!
Holdfast Training Services Trial Blog 
I found a piece of toilet seat in our 6F2 on site once, and an ornamental iron tap, I think there was once some nice pottery in there too! I think the default setting for everything was 600mm 6F2 with some terram at the bottom!!
Maybe we should have a “weirdest thing to find in your 6F2” competition?!
Guz
And how long have you been there? Why did the tipper tip? Crane bases are critical as when things go wrong they go WRONG.
All the best
2 whole weeks now! The tipper is a long story best left for TMR1 I think, so I wont ruin the ending…
I’m off to inspect the crane base again now, really being rigid with them now!
Guz,
Hopefully you have read MCHW Volume 1 clause 12 that limits Class X material to 1% by weight, which given the density of plastic and wood compared to crusher run rubble is visually quite a lot! i.e. there is no reason why you shouldn’t find pieces of wood, old toilet seat etc in amongst the stone fraction of 6F1 as long as it meets the grading requirments of table 6/2 (page 61) and the overall material properties meet the requirements of table 6/1 (page 31). What matters really is that the material as a whole compacts correctly to provide the temporary platform you need. Timber being deliterious would render 6F1 unsuitable for many permanent works situations but is not necessarily an issue for a piling platform or similar.
Sorry forgot to say 6F2 is even less stringent that 6F1 in terms of material composition/properties so you’re goimg to get even more variation in acceptable material.