Curing time for concrete structure before removing framework.
* introduction:- in this topic we know about curing time for concrete structure before removing framework and we know that concrete is poured in casting mould or box made of steel or wood . Generally concrete is made of sand cement and aggregate and it can make roof slab, column ,plinth beam, wall beam ,lintel beam and different size of rack and etc. For making this structure all the concrete poured in different size of framework made of steel or wood frame. Before casting the Roof Framework is ready by labour or contractor.
* main topics:-
1) what is framework
2) shuttering of framework
3) concrete casting
4) curing time of concrete
5)deshuttering of framework
6) striking time of deshuttering
7) factor affecting curing time and deshuttering
8) important precaution during deshuttering
1) what is framework:- framework of wood or Steel is designed by labour contractor or Mistri different size according to desire size of slab plinth and Beam construction.
2) shuttering of framework:– before casting the concrete shuttering of Framework is ready by labour contractor and Mistry in whitch concrete is poured to gain Desire shape and strength. It is vast and risk work done by labour and Mistry and it has high risk to affect the wall structure and hazards of labour and Mistry, so expert labour and Mistri done this work of shuttering.
3) concrete casting:- when shuttering Framework is ready now we can mix the Desire concrete ratio of M20 or M25 that is good concrete mix. Now concrete is poured in molded casting box and by compressor and vibrating machine we make the levelling of concrete . And concrete gain high density.
4) curing time of concrete:- we can make roof slab ,wall beam, lintel beam ,plinth beam and column and different size of rack with the help of concrete work. All these structure needs curing time to gain its strength and hardening. Curing is watering of concrete for few days to gain its strength and hardening .There is different curing time for all these structure:
a) roof slab above 15 feet :-14 days
b) roof slab above 20 feet:-21 days
c) wall beam :-7 days
d) lintel beam plinth beam:-7 days
e) column :-7 days
f) different rack and slab:-7 days
5) deshuttering of frame work :- when we apply proper curing from water for concrete for a few days ,concrete acquire its strength and hardening now one major work is done is removing of framework is called as deshuttering . Deshuttering is done by proper expert labour and Mistri because it has high risk and affect the wall structure and hazard to the labour and Mistry.
6) striking time for deshuttering:- there are different striking time for different structure like roof slab, column, plinth beam, lintel beam ,wall beam and Rack and slab. We can remove framework of wood and steel when concrete gain proper strength:-
a) roof slab :-14 -21 days
b)column :- 7- 10 days
c) plinth beam :- 5 – 7days
d) lintel beam :- 7-8 days
e) wall beam :- 7-10 days
f) rack and slab :-5 -10 days
7) factors affecting curing time and deshuttering:-
A) grade of cement:- we know that portland cement it comes in the three form grade 33 grade 43 and grade 53, higher the grade of cement higher and fast its hardening and gaining strength so grade 43 and grade 53 cement have less curing time and deshuttering than grade 33 of Portland cement.
B) grade of concrete mix:- there is a five types of concrete mix M5, M10 ,M15 ,M20 and M25 , first three is ordinary concrete and last M20 and M25 is standard concrete used for construction of civil work, standard concrete mix require less curing time and deshuttering than ordinary concrete mix.
C) temperature:- temperature also affect the hardening and strength of concrete .in high temperature zone hardening and strength of concrete is faster than lower Temperature zone.
8) important precaution during deshuttering:-
Deshuttering of framework has higher risk and vast work it may affect the wall structure and more dangerous and hazard to labour and Mistry. we should proper remove the framework, we should first start to remove vertical support then we start to remove horizontal support of wood or steel.
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