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Posted: Fri Jan 11, 2008 11:35 am
by fsengsec
Hi there, this is my first time on this forum, please be gentle......
I have got lots of ground work to do, gravel parking, block drive and paths etc, so thought I would invest in a wacker (compactor) plate.
Looking at the machine specifications I can see the compaction force is expressed in kN (kilo/Newtons), obviously the greater the kN figure, the greater the compaction.
I have read on the forum that 60kN force is required when preparing drives etc. However,very few wacker plates seem capable of producing this. Looking at vibrating rollers, which I thought would be capable of producing much greater values, I see that this is not the case as they are often rated at values much lower than wacker plates!
I must have got it wrong somewhere. Be most grateful I anyone out there could explain the theory and advise what sort of machine I should look for.
Many thanks.
Posted: Fri Jan 11, 2008 1:28 pm
by surreyhillslandscapes.com
A pedestrian roller is what i tend to use on anything that is going to be driven on, just make sure you have good quality base at a good depth and give it a few passes, use a wacker plate to any areas you can't get to with the roller. The wacker on it's own will be fine for foot traffic.
Posted: Sat Jan 12, 2008 10:18 am
by fsengsec
Thanks very much for info' surreyhillslandscapes.com. I have no doubt you are quite correct and I will probably end up buying both a pedestrian roller and a wacker plate.
I am still struggling to understand the specifications, will a pedestrian roller with say 16kN centrifugal force produce the 60kN compaction required? Clearly they must do which is why everyone uses them, I just can't get my head around the specifications and theory behind it!
Many thanks.
Posted: Sat Jan 12, 2008 12:49 pm
by surreyhillslandscapes.com
Think you probably need to speak to Steven Hawking or at least someone who paid attention in science class, all I know is that a roller does the job, compaction is key!
Posted: Mon Jan 14, 2008 11:15 am
by Tony McC
It all gets a bit complicated because the the centrifugal force plus the mass of the piece of kit. Generally speaking, most of the plates used by driveway contractors are too light to compact sub-base material but are fine for the laying course and the blocks. HAUC produce guidance on suitability of kit to achieve compaction of sub-base material, and the bottom line is you need a plate with a minimum mass of 80kg.
Most ped rollers (single drum) will be satisfactory for 100-150mm of sub-base, but a double drum is better.
I've been trying for the past 4 years to condense the guidelines on compaction kit into an easy guide for contractors but the biggest problem is the info provided by the manufacturers: the only way for me to do it would be to produce a comprehensive listing of all current models, and that just isn't feasible. Consequently, all I can currently recommend is that contractors check the spec of their machines, paying particular attention to mass, plate area and downforce (kN). A good rule-of-thumb is that, if you can lift it on your own, it's too lightweight for sub-base.
Posted: Mon Jan 14, 2008 11:48 am
by fsengsec
Thanks very much Tony, bit of a nightmare this (lol at surreyhillslandscapes.com - thanks)! I can see that force exerted by both wacker plates and vibrating ped' rollers will be the product of:
a. Mass of the machine
b. Surface area of plate (or contact area for the rollers)
c. Dynamic force exerted as a result of the vibrating mechanism.
Just not sure how they all related!
Belle have come up with a 'dual action' device:
http://www.belle-group.co.uk/en/products/compactit.html
As this design effectively reduces the surface area of the plate, I can see how the compaction force will increase. They are measuring only the static element of the force, but I imagine that the dymanic centrifugal force will increase by a similar proportion. (Not sure if their comparison against rollers is correct). Just to confuse things, they are using kgs/sq m
I will research HAUC, thanks for info', much appreciated.
Posted: Mon Mar 10, 2008 4:22 pm
by Bob_A
Tony McC wrote:It all gets a bit complicated because the the centrifugal force plus the mass of the piece of kit. Generally speaking, most of the plates used by driveway contractors are too light to compact sub-base material but are fine for the laying course and the blocks. HAUC produce guidance on suitability of kit to achieve compaction of sub-base material, and the bottom line is you need a plate with a minimum mass of 80kg.
Most ped rollers (single drum) will be satisfactory for 100-150mm of sub-base, but a double drum is better.
I've been trying for the past 4 years to condense the guidelines on compaction kit into an easy guide for contractors but the biggest problem is the info provided by the manufacturers: the only way for me to do it would be to produce a comprehensive listing of all current models, and that just isn't feasible. Consequently, all I can currently recommend is that contractors check the spec of their machines, paying particular attention to mass, plate area and downforce (kN). A good rule-of-thumb is that, if you can lift it on your own, it's too lightweight for sub-base.
I know this is an old thread but rather start another......
So you need at least 80Kg to compact sub-base. I'm guessing that's for a typical 150mm of sub base.
What if you have a 60 or 70Kg machine. More time consuming but could you not build the sub base up in levels of say 50mm and use a 60/70Kg machine at each level.
Or doesn't it work like that?
Posted: Mon Mar 10, 2008 5:36 pm
by lutonlagerlout
i have down a lot of drives with a wacker that weighs about 65kg (well i did till the pikeys nicked it) and have never had one sink ,apart from when i left a lad and he put 100mm of building sand down (another story)
i think a lot of it is making sure the subgrade is sound and also making a lot of passes from different directions with the wacker
however i will be using a roller from now on, my only training for B/paving was about 20 years a go when a rep came out and said 100 mm hardcore and 60 mm sand wacked then screeded
that was it like 5 minutes
not a lot ,but we all know better now eh?
LLL
Posted: Tue Mar 11, 2008 8:22 am
by warnergrounds.co.uk
Our Compactor Wacker we bought of the dreaded auction site has died on us. We had the Wacker rep some over last night and the other half is about to spend more than our first car cost on a new one! Before we do does anyone have any experience with whether we should ask for the Honda engine/Robin engine or the Wacker WM 170 engine!
Also is it worth spending the extra on the bigger WP range or is the VP range enough for most domestic installations?
Thanks guys - you know us girlies and our technical specs 
Posted: Tue Mar 11, 2008 6:59 pm
by Dave_L
Bomag plate with Honda engine - you'll not go wrong.
Posted: Tue Mar 11, 2008 9:17 pm
by Pablo
I've owned both and found the vp to be better due to where the handle is fixed. The Wp tends to dig into your screed bed when you pull it backwards and they have the same compaction ratings so no point buying the more expensive one. The one I have now is a VP with a 500mm sole plate and honda engine and it's perfect and heavy enough for all domestic paving and landscaping that we do. The lifting handles will fall of though and cost 20 quid each to replace so I welded on lugs on instead. Bomag and wacker are the industry leaders and as such cost more than most but are worth it.
Posted: Wed Mar 12, 2008 11:39 am
by Edgecraft
Don't be put off buying second hand because you've had a bad experience, you just just have to make sure it hasn't been worked to death.
I've had a small 5.5hp Honda Wacker for years that I bought second hand and it is still going strong, and when I'm not using it one of my mates has usally got it, and it doesn't skip a beat !
For Sub Base I have a big old forward/reverse Diesel Farymann Wacker, also bought second hand and the bloody thing is bomb proof, OK so it looks like your starting a vintage car when your cranking it, but it never lets me down !
Darren
Posted: Wed Mar 12, 2008 6:55 pm
by Rich H
The good thing about the Hondas is that before long you end up with loads of them, so many of the parts are interchangeable - cultivator, dumper, wacker, etc. etc.
Posted: Thu Mar 13, 2008 11:08 am
by warnergrounds.co.uk
Thanks for all the advice guys. The wacker is on its way to site now! Will report back but Gavin sounds like a 5 year old with a new Tonka truck from Father Christmas!!!
Cheers again guys
Lara
Posted: Thu Mar 13, 2008 7:43 pm
by lutonlagerlout
you have a PM lara
LLL