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ROADSIDE DRAINAGE, image, image, image, image - Coggle Diagram
ROADSIDE DRAINAGE
PROCESS OF CONSTRUCTION
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2) Digging/Excavation
The surveyor marked out the depth of the trench to be excavated with a mechanical excavating machine.
For a 1m x 1m drainage, the mathematical process of obtaining the required dept is to sum together the depth of the required drain + base + blinding.
For depth:
A drain of 1000 mm deep, base of 150 mm and blinding of 50 mm.
Hence 1000mm + 150mm + 50mm = 1200mm (1.2 m)
So an excavation of 1200mm (1.2m) is required from the to level of the road surface
For width:
A minimum of (2.5 x width) m is advisable.
For a 1 m x 1m drainage, since the drainage internal width is 1m, using 1.5 x width = 2.5 x 1m = 2.5m
2.5m width excavation minimum is acceptable to create space for construction work area.
3) Concrete Blinding
Blinding is done on the surface area in order to correct any irregularities in level of the bed of the excavated surface, and to provide a smooth, level and regular surface to receive the concrete base. It’s usually ±50 mm depending on the rate of regularity of the surface area. Concrete Grading C10 or C15 as sub-soil might required
The blinding is a mass concreting and its advisable to spread to cover entire width of the excavated trench except where there is need for material management.
4) Reinforcement (iron Rod) Positioning
For a 1m x 1m drainage, a 12mm U shape reinforcement (spaced between 150mm to 300 mm or as designed) is placed into position on the blinded surface but positioned at the centre of the base with the aid of concrete biscuit to create a concrete cover.
There should be concrete cover between the reinforcement and the base of the drain concrete base and the top of the drain wall.
Reinforcement Rod height needed should be;
1000mm (reinforcement height) + 75mm (base top conc. Cover) - 25mm (wall top concrete cover) = 1035mm (1.035m)
For width:
A minimum of (2.5 x width) m is advisable.
For a 1 m x 1m drainage, since the drainage internal width is 1m, using 1.5 x width = 2.5 x 1m = 2.5
2.5m width excavation minimum is acceptable to create space for construction work area.
5) Laying Of Concrete Base
A concrete base of 150 mm is to be laid or cast on the blinded floor, concrete grade C20 of ratio 1:2:4 is allowed (See concrete grading and mix ratio).
A guiding panel is placed into position to guild in the laying of the concrete base in order to achieve a uniformly alignment base edge, thickness and width, also to manage concrete material while pouring. The base is cast with the U shape reinforcement bottom in between the concrete base achieving concrete cover below and above.
6) Position The Side Wall Panel Form Work
The floor base is marked to give the required one meter (1000 mm) internal width where the panel will be positioned. The panel wall spacing is 100mm, and wall height of 1000mm (1 meter), the panel is lubricated, clipped and prepared to accept the concrete.
After casting, and setting, the panel is removed and concrete cured.
7) Back Filling And Compaction
Compaction of the back filling is done immediately after the back filling in order to avoid settlement.
TOOLS, MACHINERIES, PLANT & EQUIPMENTS
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