PYRENEES QUARRIES PTY. LTD.
Pyrenees Quarries – Your One Stop Stone Suppliers
LAYING PAVING – RECOMMENDED INSTRUCTIONS
Excavate the site so the minimum thickness from the top of the finished height to the ground is about 75mm for pedestrian or 100mm for vehicle. Drainage and fall need to be considered at this stage. Customary is about 20mm of fall per meter for exterior surfaces, (this equates to about 1/3rd of a bubble on a standard 4ft spirit level – by knowing the look of the bubble you can work into areas without known heights). The excavation requires the removal of any organic or soft earthy material and if required filled with stable masonry fill, such as rocks, bricks or concrete – larger areas may require compacted crushed rock.
A mix of crusher dust (10 shovels) bricky’s sand (4 shovels) and cement powder (2 shovels) is the customary slurry in which to lay the paving. The mix should be wet enough to bed the stone in so it sticks well, but not so wet the stone sinks - the thickness of the slurry and even the heat of the day will effect this, so a judgment needs to be made by trial and error on the day.
Normally the outside perimeter stones are laid first – this initiates the outside perimeter lines and levels (remember drainage fall). When using random stone, the outside (perimeter) pavers are generally selected for being larger – this reduces the possibility broken edges and enhances the final appearance of the work.
When laying, pour about one wheel barrow full of concrete on the prepared ground, then bed the stone onto that before mixing the next concrete slurry.
“Fitting” the stones into place usually requires chipping or cutting of the stone to make a tight fit (the normal is a uniform 10mm cement gap between stones but is personal choice and to required look). If a lot of cutting needs to be done then a bricklayers saw is often a good idea, though a masonry or diamond blade on an angle grinder may be used – cutting normally only performed when laying sawn edged products. For shaping random stone, use a brick hammer and anvil (piece of railway iron etc about 300mm long is ideal). The stone is placed over the edge of the anvil and the edge of the stone is chipped off. Chip off small pieces at the time whilst ensuring you keep the edge of the anvil immediately under the point the brick hammer hits. Note: if you tap the hammer lightly on the stone in a few different spots, you soon find the best point of contact, before you give a sharp fast strike to do the required break (experience helps – practice first).
Once the stone is placed on the cement base it will require leveling using a spirit level (4ft recommended), removing or adding cement underneath to get the height right. At this stage the cement should not come above the surface height of the stone, and is best left less than halfway up the joint between the stones (this will be plastered in later).For larger areas use a long straight edge with the level on top as required.
The thickness of the joints between the stones is purely personal choice, though 10mm (standard brick joint) is the norm. Wider variations are generally used when laying random stone.
Once the paving has dried enough to walk on (usually overnight) it is ready for pointing. This requires a mix of clean fine sand such as rendering sand or a low clay bricklayers sand. Coloured sand or off white cement may be used for colouration. The normal mix is at a ratio of 8-10 shovels of sand (depends on sand) to 2 shovels of cement powder with 1 shovel of hydrated lime. A reasonably wet mix is required so as to permit the mix to readily drop into the joints.
Using this mix (we normally wear knee pads and place the cement mix “mud” on a tin board about 2ft square) the “mud” is chopped into the joints using the side of the trowel to unsure all cavities are filled, then leveled with the flat of the trowel so the “mud” is level with or proud of the finished surface.
The next stage is the cleanup. This must be done at the correct stage - this is when the “mud” has set sufficiently so brushing or scraping it out will not smear it, but is still sufficiently soft as to be removable. This time will depend on the weather (heat, wind, humidity etc), generally though within a 2-10 hour time range. The normal process for cleanup is to scrape the surface of the stone with the side of a trowel back to the level of the joint, then wire brush the joints removing excess plastering “mud” back to the required depth without digging too deep and removing all residue from the stone surface. After this, the job is normally left for at least 2 days (preferably a week) before acid washing. The normal mix is about 20 parts of water to one part of hydrochloric acid (do not handle acid without first reading safety instructions supplied with the acid – available from most hardware stores), applied using a coarse broom or scrubbing brush adapted to a broom. Any cement lumps or residue will become obvious at this stage as they will “fizz”. These may be removed with a scraper and/or further scrubbing with acid. Once the acid washing is finished, flush away all residue with water and the job is complete.
Limestone, Marble and Travertine stones are composed of Calcium Carbonate.
Calcium Carbonate reacts with acids.
Cement is also composed of calcium carbonate, and acid is commonly used to clean off excess cement.
We recommend acids are not used to clean cement from stone composed of calcium carbonate (Limestone, Marble, Travertine) as the acid eat into the surface of the stone thus damaging the surface. This may cause a change to the surface of the stone, in general making it whiter, powdery and with a matt lustre.
Cleanup on Limestone, Marble and Travertine should be done before the cement sets, utilising water, or water with detergent. On partially dry cement a pressure washer or pressure hose may be used.