Pouring Concrete
1. Overview
Set & Alignment
Setting of walls start with plug the first three rows together. In doorways, insert the first row together as a distance piece. Subsequently push the wall exactly into the position previously marked on the floor slab.
The Trestle Support is designed as an integral part of the construction process. Being of strong steel frame construction, the trestle is connected to the MERCADO-House formwork as the wall is built. Trestles are anchored to the floor and provide full stability to the wall as well as an adjustment for ensuring that the walls are perfectly vertical.
A support arm and hand rail provides a facility for a walkway at a suitable height for the concrete pour.
Note: Health and Safety regulations must be followed when using as a walkway (modify to suit). It is recommended that trestles are positioned within 1 metre of each corner and thereafter at approx. 2 metre intervals.
2. Horizontal sealing
Horizontal sealing
In/under first row fill in commercially available sealing slurry with a pail to fight rising moisture. That is the easiest way to secure the horizontal caulking against rising moisture. After plugging together the first three rows, leveling, aligning and affixing with installation foam, pour liquid sealing slurry from above into the elements, so that the floor is covered around 5 mm. Along with the rising moisture, the sealing slurry also bridges fine cracks between the wall and the floor. If there is only slight moisture loading, when forming the floor slab and the wall with water impermeable concrete and with clean formation of the anti capillary granular sub base (base course) you could also omit the sealing slurry.
Commercially available rolls of bitumen roofing paper are also recommended as the first separation layer.
3. Pouring concrete
Pouring concrete
Generally it is not necessary to stir, vibrate, pound or similar, in order to eliminate voids. This is only carried out on walls heavily reinforced with steel, and even then, only by hand tamping. To confirm that there are no voids simply tap the walls.
Filling with an auto concrete pump is the normal case. The following instructions are based on yearlong experience with machinefilling formwork elements. The auto concrete pump must be continuously adjustable. The pump operator must be qualified to operate said machinery and have the necessary experience required. If need be, the operator will have to pump smallscale pumping discharges and be able to place the final hose exactly over the wall without a hitch.
When filling, pay attention that the concrete jet is always kept on one rib of the formwork element. The rigid foam rib should be shifted in at least every fourth row to prevent any possible free fall. It is recommended to order only one truck mixer to avoid waiting times and premature setting. Also, filling should be done at the start of a week because of the time requirements (5 m³ per hrs) to avoid time pressure and rushing.
Notes!
The pump hose should be fitted with a type 65 exit nozzle. MERCADO-House formwork has a density of 30kg/m³ which will allow a type 100 exit nozzle to be used. However, the greater the diameter, the higher the pressure load when pouring, making the accurate placement of the concrete into the void more difficult.
4. Equipment and concrete
fourth descriptions and specifications......
Quality of concrete
The concrete should be a ready mixed, uniform pump grade C20-25 for the walls and C28-35 for the foundation. 10 mm should be the maximum aggregate size with a minimum 350-375 (kg/m3) cement content and a slump factor of 75-120mm.
5. Finished walls
After the pour
Check all walls are vertical, then adjust by pushing, where necessary before the concrete has had time to cure.
By the following morning it will be too late!
If you have used the trestle support system correctly, you will probably not need to make any such adjustments, but its good to check anyway.
Here you can go back to the overview.
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