Factors effecting the determination of lateral pressure of concrete:

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One of the design factors of column formwork is determining the amount of lateral pressure of freshly poured concrete. Because column formwork is usually filled quickly and it often takes less than an hour to concretize a column, the amount of pressure applied can be significant. Mentioned below

height

1- Concreting speed of concrete (in terms of depth per hour) The average speed of concrete rising is called concreting speed, which has the most important effect on the lateral pressure and the maximum lateral pressure is proportional to the concreting speed.

2- Concrete temperature

3- Vibration type of internal or external concrete

4- Impact caused by free fall of concrete on the form work

The fluidity of concrete (slump)

5- Weight of concrete

6- Amount and location of reinforcement

7- Ambient temperature

8- Pore water pressure

9- Maximum size of aggregates

10- Cross section of molds

11-Filter molds

12- Permeability of molds

13-Type of cement

14- Concreting methods

15- Additives

16- Concrete vibration

01

In the case of concrete weight, it has a direct effect on the lateral pressure because the hydrostatic pressure at any point in the liquid is caused by the weight of the upper liquid.

Internal vibration is the primary method of compacting concrete. The effect of this vibration on temporary lateral pressures is a 10 to 20% local increase over simple shoveling of concrete.

In the case of temperature, during concreting, there is an important effect on pressures because temperature affects the setting time of concrete, so the higher the height of the liquid in the sense of creating higher lateral pressures.

square and rectangular column shapes :

In such forms, the permissible concrete pressure can be determined by specifying the surface characteristics of the formwork and its backings, and by limiting the shear, flexural and deformation stresses, and from there the safety concreting speed can be determined.

In wall formwork at lower concreting speeds, the concrete of the lower part of the formwork begins to harden and the lateral pressure at the time of completion of concreting of the upper parts of the formwork is less than the full pressure of the liquid.

pressure 02

Hydraulic pressures and its effect on concrete strength

Compressive strength is one of the elements of concrete strength and factors that are effective in testing the strength of concrete: we can mention the size of the sample, moisture and geometry of the sample.

Lateral pressure on concrete formworks for columns

With a minimum of 30Cw kpa , but in co case greater than formula for pressure on concrete formworks.

Where ;

Lateral pressure on concrete formworks for walls

Concrete lateral pressure for walls with placement rate , smaller than 2.1m/h and placement height is no greater than 4.2 m.

Whit a minimum of 30Cw kPa, but in no case greater than

Concrete lateral pressure for walls

With placement rate of greater than 2.1 m/h and placement height exceeds 4.2 m , and for all walls with placement rate of 2.1 to 4.5 m/h

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