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usually) was particularly emphasized in past construction technology of Civil
Aviation. When the last
finished manually, dehydration crack
emerged again would be eternal injury and weak point of concrete. Technical
indexes of practical concrete in the future, such as strength, frost and permeability
resistance, and durability, were closely associated with these cracks (especially
cracks emerging on concrete surface). It was the same principle as Bucket Theory
we commonly talked about in the past. It is the shortest board that decides volume
of a bucket, so these cracks might decide many technical indexes of concrete.
Utilization of troweling eliminated concrete surface crack for a second time after
manual troweling. When concrete got setting further and it became dif
troweling was
cult for
troweling manually, troweling machine eliminated concrete surface crack again
relying on machinery strength, which further boosted concrete ability to resist
dehydration crack and frost and permeability at the same time. Water permeability
experiment on August 23 also demonstrated this point.
Other technologies would not be detailed illustrated here as they have no dif-
ference as compared with the past.
16.4.8 General Conclusions
One hundred and ninety-one strips of dehydration cracks generated totally within
12 h in the experiment, and their overall length was 898 cm. There were still 159
strips of crack on August 23, and their overall length was 554 cm.
Quantity and overall length of dehydration crack emerged on concrete slab
which adopted Duolang cement were much more greater than those of concrete
slabs which adopted Tianshan cement under same condition.
Addition of
cant effect on prevention of dehydration
crack generation, and the effect was best around daybreak. Therefore, polyester
fiber in concrete had signi
fiber should be applied in the construction of this airport.
Utilization of troweling machine had signi
cant effect on prevention of dehy-
dration crack generation. Therefore, troweling machine should be applied in the
construction of this airport.
Although admixture had increased concrete shrinkage, it could be compensated
by other construction measures. With descend on temperature, admixture can
drastically reduce W/C. So, it was suggested that admixture be properly added into
concrete according to variation in temperature.
Double-deck geotechnical cloth and continuous watering for 24 h should be
adopted in concrete curing.
Measures should be taken to cool down sand and stone when temperature was
too high in daytime.
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