Note: Descriptions are shown in the official language in which they were submitted.
13364~2
The present invention relates to a cement concrete pavement which is so
excellent in water-permeability that inl~rce~lion of water into the ground surface
which has become a serious problem particularly in towns and cities can be
s~lcces~fully avoided.
As the recent tendency of ur~ni7~tinn has progressed, the harmful influences
of the urbanization have become remarkable in various fields.
Rain water which could permeate into the ground is now plt;vell~d from
permto~ting into the ground and from being held in the ground by asphalt pavements,
concrete pavements, various bllil(lings, and so on. Of those harmful influences of the
urbanization, particularly the condition of such an impe liment of rain water
permeation/holding into/in the ground has become a serious problem more and moreas the urbanization has progressed. That is, as the ground surface into which rain
water can perm~t~ decreases, underground water decreases immediately so that theground subsides, the growth of trees becomes slow, or the ecology or or~ni~m~ inthe ground changes. Further, because of the above-mentioned decrease of water-
permeable ground surface and difficulty in water holding in the vicinity of the ground
surface, when rain falls concentratedly in short time even though the total rainfall is
not large, rivers overflow or trafflc networks are disrupted and serious social problem
is caused.
In a point of view different from the ro~t;going one, particularly recently, it has
become aesthetically desirable to color sidewalks, public squares, etc.
At present, the method in which various pigments are mixed into asphalt or
cement concrete in advance and such a mixture is kneaded when it is to be used or the
method in which various pigment~ are sprayed onto a pavement surface are the main
current in pavement coloring.
In view of the above-mentioned water-permeability and water-holding p-upelly,
the realization of pavement excellent in water-permeability and water-holding property
. ~
1336442
has been earnestly required and there has been proposed water-permeable asphalt to
satisfy the requirement. However, the water-permeable asphalt is not always
satisfactory because the water-permeability and water-holding plupelly thereof are not
so excellent as they are expected, the asphalt is melted by slm~hine to cause loading to
make the water-permeability more deteriorate, and time aging of strength of the
asphalt is remarkable. Accordingly, water-permeable concrete using cement concrete
has attracted attention, and provision of practical water-permeable concrete excellent
in water-permeability and water-holding plupelly is expected.
Further, in view of coloring a pavement, such methods of pavement coloring
as described above provide artificial visual feeling unlike natural colors and therefore
it cannot but to say that those methods are successful in providing the Çolt;goillg
"charm".
It is therefore an object of the present invention to elimin~tP the defects in the
prior art as described above.
As the result of earnest investigation, the inventor of this application has
succeeded in realization of a cement concrete pavement which is excellent in
water-permeability and water-holding property and which is provided with naturalcolors, elimin~ting foregoing disadvantages in the prior art.
That is, according to the present invention, the cement concrete pavement is
composed of a hardened cement concrete mixture in which
300 - 400 kg of portland cement,
0.008 - 0.04 weight portions of binder and 0.3 - 0.45 weight portions of water
relative to 1 weight portion of the cement, and
an aggregate compûsed of sand and No. 7 crushed stone at a weight ratio
within a range of from 5: 95 to 20: 80 are subst~nti~lly uniformly distributed per
volume of 1 m3 of the hardened cement concrete mixture, and in which a cement
mortar portion ~flhering to a surface of the aggregate in a surface of the hardened
cement concrete mixture is removed.
1336442
It is particularly preferable for the water-permeable cement concrete pavement
to select the ratio of the sand to the No. 7 crushed stone to be within a range of from
lO: 90 to 15: 85, because with the ratio in this range, the resulting strength is
suitable for a vehicle traffic pavement and the water-permeability can be secured to a
required extent.
Further, it is preferable to select the binder to be 0.015 - 0.03 weight portions
relative to 1 weight portion of the cement or to select the water to be 0.35 - 0.40
weight portions relative 1 weight portion of the cement. The quantity of the binder
t;senl~ the quantity of solid portion of resin in emulsion.
Further, in balance between strength and permeability, it is preferable to use
the cement by an amount within a range of from 320 - 370 kg per 1 m3 of the
water-permeable cement concrete.
According to the present invention, in an area of pavement on a sidewalk, a
public square, or the like, an agglega~ exposed on the surface of the pavement
exhibits a natural colour held by the aggregate per se through shot blasting tre~tm~nt,
to thereby give aesthetic appeal unlike the co-lvel lional colored pavement which has
given artificial visual feeling.
Further, because of the foregoing configuration, the water-permeable cement
concrete pavement according to the present invention shows the same water-holding
plopelly as that exhibited by ordinary soil in rain fall and realiæs rapid water-
permeation which cannot be compared with the co-lv~ntional asphalt pavement or the
conventional cement concrete pavement, while the water-permeable cement concretepavement according to the present invention has sufficiently large strength for
practical use. In the cement concrete pavement according to the present invention, it
is possible to obtain the rate of water permeation of the order of 10-l- 104 cm/sec,
typically, of the order of 10-l - 10-3 cm/sec.
-~r
1336442
The water-permeable cement concrete pavement according to the present
invention is remarkably different from the conventional water-permeable asphalt
pavement in that in the former, no loading is generated, time again is gentle, no
melting is caused under the condition of a high ~~ ture, and so on.
Moreover, the water-permeable cement concrete pavement according to the
present invention has eY~ee~ingly high voids of 10 - 30% in spite of its strength. As
a result, even if fine earth and sand or the like are accumulated on the surface of the
concrete pavement, the earth and sand can be passed through the voids when rain falls
so that the pavement is cleaned without causing any loading.
The water-permeable cement concrete pavement according to the present
invention has strength which is sufflcient for practical use while the pavement has the
large voids and sufflcient water-permeability as described above. The compression
strength of the concrete pavement is 200 - 300 kg/cm2 (the strength after 4 week~s
curing in constant-l~lllpel~ture water of 20C), and the flexural strength thereof is 20
- 30 kg/cm2 (the strength after 4 weeks curing in constant-~lll~l~ur~ water of 20C).
The water-permeable cement concrete pavement according to the present
invention is produced in the process comprising the steps of: kne~-ling, per lm3 of a
cement concrete Illi~Ul'e, 300 - 400 kg of portland cement, 0.008 - 0.04 weight
portions (solid portions) of binder and 0.3 - 0.45 weight portions of water relative to
1 portion of the cement, and an aggregate forming the balance being composed of
sand and No. 7 crushed stone at the ratio within a range of S: 95 to 20: 80 by
weight to thereby obtain a cement concrete mixture; pouring or injecting the thus
obtained cement concrete mixture into a mold; hardening the cement concrete mixture
to thereby form a concrete pavement; and washing the surface of the concrete
pavement to remove cement mortar portions ~(lhering to the aggregate surface in the
concrete pavement surface by using a grinding/sweeping machine (commonly-called a
shot blasting machine).
i~
1336442
In the aggregate according to the present invention, it is necessary to select the
weight ratio of the sand to the No.7 crushed stone to be within a range of from 5: 95
to 20: 80. The ratio of 5: 95 is suitable to produce a concrete pavement for
sidewalk, while the ratio more than 10: 90 is suitable to produce a concrete pavement
for light traffic. A part of the aggl~ale, preferably, 10 - 30 weight percent of the
agglc~ale~ may be substituted by No.6 crushed stone having a particle size of
13 - 5 mm. In this case, there is a disadvantage in that the external appearance of the
concrete pavement becomes poor because the large-sized No.6 crushed stone co-exists
with the No.7 crushed stone, although there is an advantage in that the strength of the
concrete pavement is increased to a certain extent.
The ~luanli~y of the portland cement is selected to be 300 - 400 kg, preferably,320 - 370 kg, per 1 m3 of the whole cement concrete ~ lu-~ including water. Binder
is added by 0.008 - 0.040 weight portions, preferably, 0.015 - 0.03 weight portions,
relative to 1 weight portion of the cement. As the binder, it is possible to use any
binder which is known as a general additive to cement mortar. That is, natural or
synthetic rubber, for example, SBR, NBR, acryl resin, epoxy resin, and the like, may
be used as the binder. Generally, the binder is added in the form of emulsion. For
example, when an SBR latex binder (JSR TOMAC SUPER, produced by Japan
Synthetic Rubber Co., Ltd.: solid portion of 0.45%) available on the market is used
by a quantity within the foregoing range, the flexural strength can be improved by
about 10 - 60%. If the quantity of the binder exceeds the range, however, the
water-permeability is undesirably considerably reduced.
The quantity of water is selected to be 0.30 - 0.45 weight portions, preferably,0.35 - 0.40 weight portions, relative to 1 weight portion of the cement. The
water-permeability is poor if the quantity of water ~Y-~eeds the upper limit of the
range, and on the contrary, sufficient knea~ling cannot be performed if the quantity of
water is decreased beyond the lower limit of the range.
As the shot blasting m~tPri~l to be used for grinding/sweeping, for example,
spherical iron (having a diameter not larger than about 2 mm) or sand (such as silica
~.
1336~2
sand or the like having a diameter not larger than 0.6 mm) is used. The shot blasting
m~tPri~l is caused to collide with the cement concrete surface by using a
grinder/sweeping machine to thereby remove cement mortar portions adhering to the
aggl~gale.
