Casting Procedure

The casting of the grade slab involves the casting of various components. By reading the following, you will understand how the casting is done.

1. First of all the top layer of the soil is removed. It is done manually of with the help of hydraulic excavator. The top 200 mm of the soil is removed so as to remove all the plants and bushes in it. If the top layer is not removed then the plants and trees may grow which may harm the structure above.
2. Then the existing ground is leveled in reference to the level mentioned in the drawings as provided by client. The leveling can be done with the help of dumpy level, auto level or total station. Now a days, on site dumpy level and auto level are being used more. The level on site is transferred from the permanent structure nearby whose level is already known. The level can be transferred using the rise and fall method. Then the temporary bench mark is constructed near the site which is used as reference for checking the level on the site.
3. After attaining the desired the ground is compacted either manually or by machine compactor. When the compaction is done the level is checked again to avoid the discrepancy in work. The addition or removal of soil is done to order to maintain the level.
4. When the compaction work is over, layer of 100 mm P.C.C. (Plain Cement Concrete. The ratio of cement, fine aggregate and coarse aggregate in P.C.C is 1:4:8) is done to create a hard surface on which the reinforcing bars can be laid. P.C.C also helps to maintain the level because if rain occurs the soil gets wet and the ground level gets disturbed. It is also difficult to lay the reinforcing bars on wet soil. It may also give rise to problem of seepage and structure instability when it is complete or during construction period.
5. Then the cover blocks are laid on the P.C.C so that the reinforcement can be tied. Cover block helps to keep the reinforcement with in the concrete. If the cover blocks are not used then the reinforcement will project outside the concrete. The projected reinforcement will aesthetically not look good plus it the reinforcement will get corroded. Hence, the structure won't be able to fulfill its serviceability and durability conditions.
6. The reinforcement is tied after the shuttering work is over. The reinforcement is laid in its position. The overlapping bars and the distribution bars are tied to each other with the help of binding wire (16 gauge).
7. The quantity of required to cast the pore is then ordered from the batching plant. Before the casting of the pore the shuttering, props, and tower are checked. If any unwanted material is present on the shuttering it is cleaned with the help of the air compressor or manually.
8. The concrete from the batching plant is transferred in the miller. From the miller it is either directly to the structure to be casted in such a way that the concrete reaches the pore by sliding on the asthelene sheet or the miller gets attached to the boom placer and then the boom placer transfers the concrete to the destination from the miller
9. The slump cone test of the concrete is done before casting of the member in order to check the slump of the concrete. If slump is more then the concrete is more workable (workability: it is an ease by which concrete can be easily spread).
10. While the casting is on the concrete is vibrated with the help of needle vibrator in order to spread it. Excessive vibration is causes segregation. It is done until a shiny surface is formed on the surface of concrete.
11. The removal of form work is done after the specified time and the curing is done.