Civil Engineering Reference
In-Depth Information
2. Secondary factor
(1) Adding AEA to increase air content. It is mentioned above that AEA has
signi
cant effect on frost resistance of semi-stiff and plastic concrete.
(2) Clay content of
fine aggregate. It is found by the author that clay content of
uence on air-entraining effect of AEA. Fine
aggregate of high clay content will lower air content when adding AEA
and decreasing freezing
fine aggregate has great in
fine aggregate with low clay
content is recommended to adopt when adding AEA.
(3) Gradient. Through the author
thawing cycle. Thus,
-
s investigation on 13 concrete pavements of
Chinese Civil Aviation airport in the north, these damages are all occurred
at station site and parking apron. However, airport runway has not been
destroyed under the same condition. After conducting research, it is
believed that the main reason is gradient of station site and parking apron is
small and the area is oversize, resulting in poor drainage (civil aviation
speci
'
cation restrict gradient of station site and parking apron is less than
0.5 % and gradient of runway cross-slope is less than 1 %). A bigger
gradient pavement drain off water smoothly, so it is different for outside
water to penetrate into concrete under same condition, which decreases
possibility of freezing
thawing damage. Therefore, water draining gradient
of project should be increased as much as possible to accelerate speed of
water draining relatively, which is a good method for decreasing freez-
ing
-
thawing damage.
-
3. Ordinary factor.
There are many ordinary factors, such as mix proportion, cement type and its
mineral composition, grading and content of coarse and
ne aggregate, outdoor
meteorological environment condition, construction technology, thickness of
surface mortar, and so on, and they all have some indirect effects on frost
resistance.
5.5 What is the Correct Using Method and Range
of Air-Entraining Agent (AEA)
In short, effect of AEA on frost resistance improvement is obvious for semi-stiff and
plastic concrete. So why not apply semi-stiff or plastic concrete rather than stiff
concrete in construction of project structure and part required high frost resistance?
That is the important question that needed to answer in this chapter.
Final purpose of boosting frost resistance is keeping engineering structure in
good condition and enhancing durability. In Northern China, there are many factors
that affect normal use and durability of engineering structure, and frost resistance is
just one of the harmful factors. The author used to state a viewpoint in this topic
that concrete science is an interacted and complex system, and there is no single
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