[GBlist] Art park - Concrete mosaic questions

["Lewis J. Matt PhD" <lmatt@alltel.net>]

You ask:
has anyone done functional outdoor mosaic work? We would like to embed
either ceramic or broekn glass directly into mortar. Does anyone know how
that will weather?

I have installed stone and brick patio floors outdoors in Pennsylvania.  I
believe that success in this venture is a combination factor of a good
foundation and use of appropriate materials.  The base or foundation must be
stable or it won't support the mosaic for long.

There are two basic base preparations, compacted sand or gravel and poured,
reinforced concrete.  Both require that you dig out the area to 8 to 12
inches below the finished level.  For a sand base, start with a weed proof
but water permeable membrane; place 2 inch stone at a thickness of 6 inches
and then work stone dust and fine gravel into the stone.  Wet and tamp
thoroughly.  Add a layer of tightly tamped sand to the bottom of the stones
of your mosaic.  Add the stones adding or removing sand to make the stones
level.  When all stones are in place, add a mix of dry sand, gravel and
Portland cement between the stones and compact.  Wet down and add more dry
grout as needed to fill the intercises.  This should last 50 years.  Repairs
can easily be made to areas disrupted by frost heave.

For the concrete system, put in 4 inches of tamped stone,  then pour a 4
inch layer of concrete, reinforced with 10 gauge mesh.  Broom finish the
surface so that it has tooth.  Set your mosaic stone in a Portland cement
and sand mortar (do not use lime) base and level the stone.  After the stone
is laid and the mortar set, grout the stone with Portland cement and sand
mortar and strike the joints to make them waterproof.  This method will also
last for about 50 years, but will be more difficult to repair if spalling
results from freeze-thaw cycles.  Colored grout can be made by using white
Portland Cement with colored sand.  Sand can be white, yellow, tan. brown,
black and red (brick dust).

Lew



Synergistic Solutions: Alternative Septic and Energy Systems
Lewis J. Matt III, Ph.D., C.S.E.O.



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