Steps Involved in Workability
There are the following steps involved in the workability of concrete.
1) Mixing (Steps Involved in Workability)
The first major step involved in workability is mixing. The principal purpose of mixing is to produce an intimate
Mixture of cement water, fine and coarse aggregate and possible admixtures of uniform, consistency through each batch. This is achieved in machine mixtures of resolving drum type. On large projects moveable mixing plants are installed and operated at the site.
2) Conveying (Steps Involved in Workability)
Conveying of most building concrete from the mixture of truck to the forms done in bottom dump buckets or by pumping through steel pipe lines. The chief danger during conveying is “segregation.” Which is the phenomenon in which lighter material especially water tends to rise and heavier particles settle down and this is stopped by drum wheeler.
Placing is the process of transferring the fresh concrete from conveying device to final place in the form. Prior it placing loose rust must be removed from reinforcement, from must be cleaned and hardened surfaces of previous concrete lifts must be cleaned treated appropriately.
Problem during placing is honey combing “which is the structure in which final and coarse particles displaces.
It is reduce by use of vibrators
After placing we compact the concrete for strength. Fresh concrete gains strength most rapidly during the first few days and weeks. Structural design is generally based on 28 day strength, about 70% of which is at the end of first week after placing. Final concrete strength depends greatly on the conditions of moisture andtemperature during this initial period.
“The maintains of proper condition during compacting is called curing.” Concrete should be protected from low moisture for at least 7 days and in more sensitive work up to 14 days