The HY brand new
type underwater un-dispersing concrete is supervised the manufacturer by the science and
technology spreading center which belong to The Irrigation Works Department of the Chinese
government and produces by the pointing-divise developing base—the new materials developing center of the Zhong Shan new type materials
generial factory.
Some
kinds of powders or aquas products which consists of many kinds of surface active agents
are put into regular concrete at some proper quanitity and then the regular concrete has
been changed into the new underwater un-dispersing concrete. Compared with regular
concretes, the new type one has some particular properties. It can change the antiently
fussy methods for underwater works such as making cofferdam first and then drain and easy
the engineering technology and machine greatly. It also decreases the risk of the
underwater works. If the new materials and the new engineering method thereout be used,
the multivesity of the underwater works can drop 20~30% and shorten the engineering period
40~50%. And in other aspect, some thin-walled, narrow or particular structures can be
finished underwater which could not come to true in the past time. Therefore, the new
concrete is appraised as “brand-new” and “excellent” concrete by the
engineering circles and it has opened a new time of the concrete underwater projects.
Technical Features
The underwater un-dispersing
concrete that put up by the HY brand new type un-dispersing agent has the following
technical features:
Dispersing-resistance —can do projects underwater and do not need drainage. Ensure the concrete
mixing un-dispersing un-isolating while the concrete being cast.
High fluidity—the concrete mixing can become smooth and fix all little gaps self-motion.can
be density self-motion—the concrete can be dense self-motion,not need vibration and can meet the
need of strength.
Multi-uses—According to different design demands and water circulation, concretes with
different features can be made, such as fast-harden type used in fighting a flood,
lower-heating type suitable for large volume and high fluidity type suitable for small gap
structure.
No-polluting—When the mixing falls in water, it resists the wash of the water, very little
cement in the mixing can be loss, therefore,it can not pollute the water where the project
is in operation.So this is an environmental protection type green engineering material.
Technical Index
Looks—french gray or yellowish powder, solid content larger than 95%.
Fluity—the slump constent of the mixing can be more than 20cm and can be more than 450cm.
Congeal Time—the time can be controled.The start congeal time of the regular formular HY
brand concrete is 5~15hours, and the last congeal time is less than 30 hours. In the mean
time, we can produce many kinds of HY brand un-dispersing agents with different congeal
time such as the fast-harden type one with only 30 minutes of its start congeal time,
according to the different demands.
Dispersity-Resistance—When the concrete mixing containing un-dispersing agents falls freely in the
water, the PH value of the water is less than 10 and the matter suspanding less than
150mg/l.
Mechanical Features—the concrete’s strength when it is underwater with the regular un-dispersing agents
is about 0.75~0.92 of the value when it is on the land and the compressive strength of the
R28 days can reach 21~30Mpa. The following is a example of the mechanical features of one
type concrete:
The compressive strength after 28
days: 26.7Mpa
The compressive strength of the axle
center after 28 days: 23.5Mpa
The compressive strength of the
splitting one after 28 days : 3.0Mpa
The tensile strength after 28 days:
4.25Mpa
The elastic modulus: 2.35?/span>104 MPa
The sink-resistance strength:
>12Mpa
The methods of Usage:
The regular method of use is mixing with the other materials at the same
time. The quantity of the agent is about 1.8~2.5% of the cement weight and the agent can
be put into the mixer at the same time with cement, sands, stone and other materials and
mixing together. The mixing time can be added for 1~2 minutes. The other method is to made
aqueous solution with the agents and in this way the adjustment of the water quantity is
very important.
A referring formular of a 20MPa
concrete is as follows:
cement: sand: stone:
water=11.53:2.27:0.46
The quatity of cement: 450kg/m3
The quatity of the un-dispersing
agent: 2% of the quatity of the cement
To
get and keep good fluity, 20kg coal-ash can be added.
Typical Operation Examples
1. The Deng
Rao enclosuring dyke fixing- project underwater in Rao Ping county of Guangdong province
The project is a
thin-plate reinforced concrete structure project with a large area. The depth of the water
is 6~8 meters. The main uses of the enclosuring dyke are to resist flood and rush down
water. It has 30 water gates, with a length of 120 meters. The inner and outer safe-guard
dams is 13 meters respective. The water-gate is related on swamp. After rushed by water
for a long time, the safe-guard dams underwater collapse, split seriously. The settle
method is to stable the basement of the enclosuring dyke and rebuild the safe-guard dams
on the both sides underwater. The new dams designed is to cast on the site a body
reinforcement concrete dam with 120 meters long, 12 meters wide and 30 centimeters thick.
And the following methods can be referred and adapted:
1) The
traditional method: to build enclosure dam, then drain out the water, lay steel and cast
regular concrete.
2) The new
technology with the un-dispersing agents: to lay steel underwater and cast the special
concrete with the water.
Form
Of Economic Contrast Of The Two Operation Methods
| Methods
of Operation
|
to
build the dams |
to
cast concrete |
project
period(day)
|
amount of work(10000m3) |
cost(10000yuan) |
amount of work(m3) |
cost(10000yuan)
|
| cast
the regular concrete(traditional way) |
earthwork: 7.2
stonework:1870 |
268.44 |
1255 |
92 |
150 |
| cast
the new type concrete(un-dispersing agent) |
0 |
0 |
1255 |
120 |
60 |
Comparing
with the traditional way which can been known from the form, the new way can save the
total investment 41.7% and short the working period 60%. The strength of the underwater
concrete all reached 20MPa, the results of the testing samples of different sites. The
project has good quality and has got good technology and economic profits. This is the
first underwater project that used the new un-dispersing agent in China .
2. The Ya Que Wei
pump station dam repairing project of Zhong Shan city in Guangdong province
The
part of the dam underwater has been hollowed out because of flood, typhoon, tide and the
water from the pumps . The dam can be collapse at any time if it is not repaired promptly.
And the water then was in high level , therefore, it is impossible to repair it using the
traditional way, no matter how many money you will spend. we use the new technology and
the HY type un-dispersing agent to construct the dam well and repair the hollowed part of
the dyke in a short time. Because the depth of the water was 3~4 meters and the water
speed was 1~2 m/s at that time, stones were dropped first and then the special concrete
cast to hard the stones. It took only ten days to finished the repairing project of 170
meters long dam and formed a concrete guarding slope underwater of 170 meters long , 6
meters wide and 30 centimeters thick. Until now, the repaired part has been well. We
studied the concrete formed at lower water time and the average compressive strength of
the concrete is 33Mpa. The dam has got good protect already.
The
bank-guard project of the YALU river in Dandong city
To
prevent collapse of the bank and other risks , increase the guarding class of the YALU
river and prolong the durability of the guarding bank ,decrease the cost of the
maintenance costs, the underwater un-dispersing concrete has been used in the
construction of the guarding-bank dams. Until now, about 2500 m3 underwater
un-dispersing concrete has been cast. The samples we take all have a strength of 20Mpa.
The construction length reaches several kilometers. The result of the works is excellent.
3. The stone-cast
and groutting project of the container dock of Qingdao harbor
In
the container docks of the Qingdao harbor , Shandong province and the Beihai harbor,
Guangxi province all have been constructed by brick-laying hollow bricks with large stone
filled in the hollows. The hollow rate is about 30~40%. As many causes, there are many
cracks in the hollow bricks and this affects seriously the usage of the docks. To repair
the cracks and ensure the ordinary use of the docks, the underwater un-dispersing concrete
mixing is affusing into the hollows. The strength of the concrete is 15Mpa, pump
transportation is used and at last the cracks are filled and fasten the cast stones.
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