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selected and controlled carefully. However, as there is only one cement
manufacturer, Tianshan, who can produce the low-alkali 42.5-grade
ordinary Portland cement we need for the construction of airport pavement
within a reasonable distance of 500 km, we have no choice. However, in
order to guarantee scienti
cness of the data and make it to be more con-
victive, we have order a certain amount of cement to do comparative
experiment according to our own construction experience in other airports
of Xinjiang.
(b) Requirement for other raw material
Local coarse and
fine aggregates are tested in accordance with requirement
of Civil Aviation speci
cation, and they all meet the requirements.
(c) Requirement for admixture
Whether water-reducing agent has positive or negative effect on generation
of dehydration crack is still the biggest disputable question in current
concrete academia. Scienti
c datum and conclusion will be obtained
through this experiment. Thus, comparative experiments that contain
admixture or no admixture will be conducted.
(d) Requirement for mix proportion
Aggregate content, Vebe consistency, sand ratio, and W/C in mix pro-
portion have effect on generation of dehydration crack. According to the
past construction experience and entrusting mix proportion experiment and
design to Xinjiang Highway Research Institute, we will also adjust prop-
erly based on
field practice.
4. Requirement for construction technology
Advancement and special requirement for construction technology and method
which have impact on generation of dehydration crack are proposed by us.
According to our past experiences, trowel
uence on
generation of dehydration crack, while variety of pavement napping and deviling
technology has direct
floating time has important in
floating times. Therefore, pavement
napping and deviling technology will be comparatively experimented. Additionally,
troweling machine produced in Shanghai has been proved to be effective for pre-
venting generation of dehydration crack after utilizing in other construction site by
construction unit and supervisor. Therefore, practical effect of this kind of troweling
machine will be experimented in the experiment.
in
uence on trowel
5. Utilization of new scienti
c achievement
fiber are commonly
employed in concrete as new material which can prevent concrete creating plastic
crack, and many scienti
In recent years, polypropylene- and polyester-category
cantly effective.
These new materials evenly distributed in concrete, which has boosted
c data manifests that they become signi
flexural
strength of concrete and restricted generation and development of crack in concrete,
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