,

n.c

C

S and St – accordingly

quantities of sand and coarse

aggregate, kg/m3

48

Application of aggregates substantially multiplies the water content of

concrete mixtures, necessary for achievement of the set mobility

(workability).

For the choice of continuous grading or particle-size distribution of

aggregates different formulas, are offered:

Formula

Author

d

У = 100

D

(2.7)

Fuller

У = А + (100 − ) d

А

D

(2.8)

Bolomey

n

 d 

У = 100 

 D 

(2.9)

Gummel

In formulas (2.7-2.9): d – size of particles of the given fraction of aggregate; D

– maximum particle-size of aggregate; A – coefficient equal 8-12 depending on

the kind of aggregate and plasticity of concrete mixtures; n – index of degree

equal in mixtures on a crushed stone 0,2...0,4, on the gravel 0,3...0,5

(in Gummel's formula index of degree equal 0,1 to 1).

49

Correction of parameters of aggregates by mixing, for example, two kinds

of sand can be executed by formula:

P − P

n

1

=