,

.9)

where R-concrete strength; C/W–cement-water ratio; A and A 1

coefficients.

79

R/Rc

C/W

Fig. 4.4. Typical relationship between strength of

concrete (R), strength of cement (Rc)

and cement-water ratio (C/W)

80

4.3. Adhesion between aggregates

and cement stone

Aggregates, making the bulk of concrete and forming the

concrete structure as composite material, actively affect

concrete strength foremost through strength of adhesion of

cement paste (stone) with their surface.

Gordon produced the test of different kinds of aggregates.

Strength distinctions of concrete arrived at 50%.

81

R, MPa

Vag

Fig. 4.5. Relationship between

volume of aggregates in the

volume of concrete (Vag) and

compressive strength (R) of

concrete:

1 –

complete coupling of

aggregates and cement paste;

2 – coupling is fully absent

82

4.4. Influence of terms and duration

of hardening concrete

Concrete strength in definite age is determined in accordance with

Skramtaev formula:

lg n

R

R