Breeding and False Setting, Which Is Better? - The Issues and Discussion of Modern Concrete Science - page 68

Fig. 6.1 Breeding of
concrete surface

6.1 Reasons for Breeding

Breeding is old problem for concrete engineering. Different levels of breeding
appear in construction board, beam, column, road, bridge, and house building, or

flowing, plastic or stiff concrete twenty years ago [ 1 ]. Nowadays, breeding in
engineering, such as house building and bridge and so on, basically disappears,
while in civil aviation is only occasionally seen. What s the reason?

Breeding usually takes place after concrete mixing and basically ends when
concrete has reached

'

final setting. Breeding is a phenomenon that momentary
redundant water in concrete under certain condition separate out concrete surface
when there s not enough space for storage [ 2 ]. Why will this phenomenon take

place? Because there is a

'

inside concrete during certain
period, breeding will happen when total water content in concrete is greater than
“

“ total water demand ”

” “

total water demand. There are mainly three factors that affect total water

demand ” of concrete: water demand of cement hydration during a period of

①

time; water demand of water evaporation inside concrete caused by climate;

③
water emissions which can compact concrete structure and lower void content after
vibration [ 3 ].

②