Growing columns in backyard ?

Overview:

Previously , we saw how the action went on from land procurement up to the construction of the basement. [ Read posts  :One ..two..three  and ..start & The building grows above plinth ]

We saw how the specimen cubes were cast and tested on 7th & 28th days from the date of casting.
We also spoke about the characteristic strength of concrete.

We went ahead and listed down all tasks that need to be executed in a building.

We also saw 4 different cases of multidisciplinary coordination.[Read post: Progress continued ..upwards ]

Now let’s go ahead and focus on the next activity ..the columns beams slab.

Background:

Basement roof slab has been cast.
Dowel bars are left protruding from the columns .

Further activities shall be undertaken as follows:

Columns above basement roof slab :

1.Dowel bars shall be lapped with new bars of the same diameter so that  the bars reach above the proposed slab .The dowel bars shall extend at least 45 times the bar diameter above the slab.
( If the bar diameter is 12 mm then we must verify that these extend for a minimum of                       45 x 12 = 540 mm above the slab level.Some situations may require that this lapping distance be maintained as 52 times bar diameter. This detail shall be provided in the RCC  drawings.
The lapping between the bars shall be tied together with the binding wire .
Binding wire is mild steel wire of 1.6 mm diameter . Some builders use galvanized binding wire which is resistant to rusting and hence improves the durability  of concrete.
Hand held portable machines are also available for tying the bars with binding wire .

LAPPING OF COLUMN BARS COMPLETED. STIRRUPS ARE BEING TIED UP.
LAPPING OF COLUMN BARS COMPLETED.
STIRRUPS ARE BEING TIED UP.

2.Stirrups shall be inserted in the main bars of the column and shall be fixed at the  spacing specified in the drawing.

COVER BLOCKS WITH BINDING WIRE FOR TYING WITH THE REINF.BARS
COVER BLOCKS WITH BINDING WIRE FOR TYING WITH THE REINF.BARS

Usually the doughnut shaped cover blocks are fixed in the stirrups so that the cover to the reinforcements is maintained.

COLUMN SHUTTERING IN PLACE. PROPERLY CLAMPED WITH SHIKANJA.
COLUMN SHUTTERING IN PLACE.
PROPERLY CLAMPED WITH SHIKANJA.

3.Form work for the column shall now be fixed on the starter.
Starter is a small piece of column which is cast before the main column is cast.
A wooden  box  of internal size exactly matching with  column size is placed in position. The center lines are checked.and concrete of the specified grade is poured in this mould .

STARTER ON THE TOP OF A TRAPEZOIDAL FOOTING
STARTER ON THE TOP OF A TRAPEZOIDAL FOOTING

The advantages of having a starter are:

a.It is easier to establish & verify the center line  of the starter than of that of the column.

b.It is sturdier to fix the column shuttering if the starter is already in place.
c.The chances of column form work becoming skew are eliminated.

4.After erecting the shuttering for column ,Bracing or supports are fixed ,the verticality is checked on two  sides ( adjoining faces ) with a plumb bob and alignment is checked with the help of a cotton or nylon thread.

5. The column shall be cast after all checks are completed with the approved concrete mix.

6.the column shuttering shall be removed next day and the curing shall be taken up. depending on the climate ( temperature and humidity ), the curing can be done either by spraying water at intermediate intervals or by wrapping column with hessian clothe and keeping it wet.

COLUMNS BEING CURED WITH WET HESSIAN CLOTHES [ THE OWNER PROUDLY LOOKS ON ]
COLUMNS BEING CURED WITH WET HESSIAN CLOTHES
[ THE OWNER PROUDLY LOOKS ON ]
Author’s note :

Thank you for reading so far with total attention.

In the next article we shall speak about the entire process involved in the casting of the roof slab.

Till then , bye bye

Take care.

AUTHOR with Construction personnel at a site
AUTHOR with Construction personnel at a site
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