Paving slabs - Vibrating table or what ??????

[deko]

when i empty my slab moulds 90% of the slabs are all chippy
just like the chips are going to the bottom of the mould when iam vibrating them.
every mix this happens and with garden ornaments, any advice would be great, thanks

[Tony McC]

Sounds like too much vibration or vibration at too high a frequency or too wet a mix. Try varying these factors one at a time to see which (if any) gives better results.

[deko]

Hi, i have tryed a semi dry mix,
I have tryed 1 bucket of chips less
I have tryed a bit more sand
I have tryed no rapid set frostproofer
I have tryed smaller chips

[danensis]

So that leaves less vibration and a lower frequency.

[the manager]

god loads of factors here
1 what size chips are you using
2 what molds are you using
3 what is the mold case made of
4 what ratio mix are you using
5 how long are you vibratin
6 how wet is yr mix

[deko]

I have tryed 1/2inch chips and 10mm chips now iam trying 5mm chips.
The mix is 4 chips, 2 sand and 1 25kg bag cement and i use 1 cup of rapid set frostpfoofer.
Most of the moulds are new from harristone, some are plastic slab moulds and some are ornamental moulds, latex with fibreglass support case.
I have tryed wet and semi dry mixes.
I have had the moulds on the table for different times.
It must be something but i dont know what.

[the manager]

are your abs molds on a wooden frame .
do you have stands for your ornament molds
for your abs paving molds make the mix close to a slack porrige mix
ie if you run your trowel through it it closes behind smoothly.vibrate untill you see air holes forming on the back of the stone.a good way to tell if you have it right is after vibration tilt your mold up if you mud slides youve got too much water in it .
for your ornament make the mix runny but not sloppy and leave on table just before the fat starts to form if this forms too quick turn your table down.