Summary Report of Experimental Study on Dehydration Crack Appearing in the Construction of Turpan Civil Airport Cement Concrete Pavement - The Issues and Discussion of Modern Concrete Science - page 225

(ii) Various degree dehydration cracks emerged on the whole concrete slab on
the second day before water curing. Their lengths ranged from 3 to 15 cm,
and width ranged from 1 to 2 mm.
(iii) Application of troweling machine had signi

cantly reduced dehydration

crack in the same condition.

(iv) It can be seen from the results that addition of fiber had signi cantly reduced

generation of dehydration crack.

In the meeting, three revising suggestions were proposed to experiment on July 7
according to experimental summary and discussion 2 days ago.

(i) As experimental section which did not employ admixture and ber was

constructed before dawn, somebody believed that increase of crack may
cause by the rapid growth of temperature after sunrise, so it was suggested
that experimental section which did not employ admixture and

ber be

arranged at the front, namely the experimental was constructed before

getting dark.
(ii) Experiments 2 days ago were added asphalt felt for purpose of preventing
effect of cement mortar downward penetration on experimental result.
However, somebody also believed that asphalt felt hindered ascending
passage for underground capillary water, and it might be adverse to concrete
durability. In order to facilitate long-term observation, asphalt felt separa-
tion layer was suggested to be canceled in experiment on July 7.
(iii) As effect of troweling machine was very prominent, it was unnecessary to
conduct any experiments again. Thus, troweling machine would not be
applied in tomorrow s experiment.

The summary meeting decided to accept these three suggestions.

'

3. Experimental process on July 7

(a) Experiment

Experiment on concrete prepared by Tianshan cement which did not employ
admixture and ber was firstly conducted, and W/C was increased to 0.46. When

the field and poured into mold,

experimental crews immediately examined regular technical indexes of air content,
slump, etc. Meanwhile, concrete strength specimens were made at the same time.
Relevant supervisors preliminarily judged the concrete from appearance, dry

first car of prepared concrete was transported to

wet
degree, and smelly or not; temperature was also checked. Thereafter, supervisors
thought that the concrete basically met the requirements and experiments could be
conducted normally.
At 22:50, the

-

first car of concrete was flatted and vibration was started; paste

generation situation was normal.
At 23:00, wooden moving rammer started working and paste generation situa-
tion was normal.