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 241

The reason why Duolang cement produced in Aksu was chosen to be compared
was mainly based on good impression on Duolang cement which was gained in the
construction of Hetian Airport 6 years ago. Hetian Airport in Xinjiang was located
at the border of Taklimakan Desert, and strong wind, high temperature, and quite
low relative humidity were its main climatic characters, which were similar to those
of Turpan. At that time, various main indexes of Duolang cement were as follows:
C 3 A content was about 1 %, C 2 S content was about 25 %, neness was 330 m2/kg,

and final setting time was 4 h plus 25 min, which was very suitable for environ-

mental climatic characters such as arid, high temperature, and windy in Southern
Xinjiang. The cement was employed in Hetian, and no false setting and dehydration
crack generated in case of 35 C high temperature and 4-grade strong wind.

Meanwhile, the cement also had good self-healing ability for crack. Thus, we
always insisted that Duolang cement had played an important role in successful
construction of Hetian Airport, which was the reason why it was chosen to do
comparative experiment.
However, experiment on night of July 5 depressed us. Under same condition,
there were 46 strips of crack in Duolang cement test section, and the total length of
which was 525 cm; there were 6 pieces of concrete slabs which emerged dehy-
dration crack, the number of cracks was 22 strips, and the total length of which was
192 cm. When checking again on August 23 for the last time, we found that there
still were 117 strips of crack in Duolang cement test section and their total length
was 318 cm. Although the total length of crack decreased, crack strip increased,
which proved that late-stage drying shrinkage was still accelerating; there were 117
strips of crack in Tianshan cement test section, and their total length was 134 cm,
which indicated that crack in test section of Duolang cement was much more
serious than that in Tianshan cement test section. After chatting with technicians of
Duolang cement factory, who was also our old friends, we knew that massive
technical alteration work had been carried out relying on gained pro

°

ts by excellent
situation of cement market in the recent 6 years; thus, there was no difference in
various cement technical indexes between their factory and other nationwide
modernized factories. Compared with cement in the past, main characters of cement
produced in modern factory were high

fineness, high strength, and maximum
mineral admixture dosage. As a result, that kind of cement which was produced for
construction of Hetian cement 6 years ago had already disappeared in their factory.
Although appearance of Duolang cement in this experiment depressed us,

absolutely different in uence of these two cements on dehydration crack generation

under the same condition made us feel that we had gained great achievement,
namely let us knew that changing of cement technical index has so much in uence

on dehydration crack generation.