Concreting technology and removing of the forms

Sagging of Fresh Concrete

     Coefficient of elasticity is achieved as early as after 3 days at the level of 90 % of the value for 28th day – regardless of concrete compounding. Thus, for the fresh concrete only insignificant increase of elastic deformations comes in. Creep strains that become apparent after a number of years, exceed the elastic deformations several times. Early removal of the formwork – say, after 3 days instead of the 28 – results in the increase of total deformations less than by 5 %. In contrast to this, the dispersal of creep strain share as a result of various influences, i. e. humidity of the filling material or humidity of the air, varies in the range of 50 % to 100 % of standardized value. That is why the total sagging of the covering slab does not depend practically on the time of removing the forms.

Solidification of Fresh Concrete
Finnish Birch Wood Sagging Graph
Pressure of Fresh Concrete upon Vertical Forms