Note: Descriptions are shown in the official language in which they were submitted.
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PROCESS OF PRODUCING WATER-PERMEABLE
CEMENT CONCRETE CONSTRUCTIONS
This invention relates to a process of producing water-
permeable cement concrete constructions and, more particular-
lye to cement concrete constructions having excellent water-
permeability and strength suitable for use as, for example,
road surfaces.
With the recent progress of city planning, evil
influences by city planning have become remarkable in various
fields.
One of these evil influences is the interruption of
permeation owe water through the surface of the earth by
asphalt pavements, concrete pavements, and various buildings
and constructions. That is, hitherto, rain water naturally
permeates into the earth but the permeation of rain water
it inhibited by the foregoing causes, which causes the
abrupt reduction of subterranean water, the subsidence
of ground caused by the reduction of subterranean water,
the delay of the growth of trees, the ecological adaptation
of living things in the earth, and flooding of rivers by
concentrated heavy rains occurring in various districts
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almost every year. These accidents and troubles now become
big objects of public concern and the settlement of
these troubles has been urgent need.
Accordingly, the development of pavements having
water permeability has been strongly desired and water-
permeable asphalt has hitherto been known as one of
such counter plans. However, a water permeable asphalt
pavement is not always satisfactory since the asphalt
is poor in water permeability and water retentivity,
the asphalt is melted by the sunlight to cause clogging,
whereby the water permeability of the asphalt pavement
is reduced, and the strength of the asphalt pavement
changes with the passage of time.
On the other hand, it has hitherto been considered
that a water-permeable concrete using cement concrete
cannot make constructions having sufficient water permeability
and strength sod a water-permeable concrete for practical
use has not yet been known.
A road structure made by using a synthetic binder
and an aggregate without using cement is known as shown
in Japanese Patent Publication No. 14,855/'78 but such
a structure is unsuitable for practical use in construe-
lion work and cost. A process of producing a water-
permeable concrete block composed ox two concrete layers
containing relatively fine macadam and relatively coarse
macadam, respectively is disclosed in Japanese Patent
I,.
_
Publication (Unexamined) Nos. 10,620/'78 and 30,628/'78.
However, these concrete blocks are not always satisfactory
in the point of water permeability as well as the unswept-
ability for executing a large scale construction on the
spot.
As the result of various investigations for obtaining
cement concrete constructions having excellent water
permeability and capable of being used as practical road
surfaces, the inventor has discovered that a cement concrete
construction made of specific compounded materials has
excellent water-permeability and strength and shows very
less change of the water permeability and strength with
the passage of time, and based on the discovery, the
inventor has succeeded in attaining this invention. It
can be said that the discovery is utterly unexpected in
view of that the production of a satisfactory water
permeable concrete has hitherto been considered to be
difficult.
Thus, accordirlg to the first embodiment of this
invention, there is provided a process of producing a
water-permeable cement concrete, which comprises kneading
a mixture of 300 to 400 kg of port land cement per my
of the cement concrete mixture and 0.008 to 0.04 part
by weight (as solid component) of a binder and 0.3 to
-- 3 .
0.45 part by weight of water per one part by weight of
the port land cement, the rest being an aggregate sand
and I macadam in a weight ratio of 5 . 95 to 20 : 80;
flowing or casting the kneaded mixture thus obtained,
and hardening the mixture.
Also, according to the second embodiment of this
invention, there is provided a process of producing a
water-permeable cement concrete construction, which comprises
kneading a cement concrete mixture of 300 to 400 kg of
port land cement per my of the cement concrete mixture
and 0.005 to 0.1 parts by weight, preferably 0.008 to
0.04 part by weight, of a binder and 0.35 to 0.45 part
by weight of water per one part by weight of the cement,
the rest being an aggregate; said aggregate having the
particle size distribution that the weight percentage
of the particles passing through a 5 mm sieve is 50 to
100~, the weight percentage of the particles passing
through a 2.5 mm sieve is 8 to 25%, preferably 8 to 18%
when a water/cement weight ratio is 0.35 to 0.43 and
is 0 to 18%, preferably 5 to 15% when a cement/water
weigh ratio is 0.43 exclusive to 0.45, and the weight
percentage of the particles passing through a 1.2 mm
sieve is 0 to 6%; flowing or casting the kneaded mixture
thus obtained; and hardening the mixture.
I
The accompanying figure is a graph showing the particle
distributions of aggregates used in the examples of this
invention and comparison examples.
The first embodiment of the invention provides a
process of producing a water-permeable cement concrete
construction by kneading a mixture of 300 to 400 kg of
port land cement per m of the cement concrete mixture
and 0.008 to 0.04 part by weight of a binder and 0.3
to 0.45 part by weight of water per one part by weight
of the cement, the rest being an aggregate comprising
sand and #7 macadam in a weight of S : 95 to 20 : 80;
flowing or casing the kneaded mixture thus obtained;
and hardening the mixture
The term I macadam means macadam which passes
through 5 mm sieve but does not pass through a 2.5 mm
sieve Also, the expression "per my of the cement
concrete mixture" is concerned with a so-called theoretic
eel density of the mixture calculated excluding the void
in the mixture.
In the first embodiment of this invention, the Sunday
macadam weight ratio in the aggregate comprising sand
and I macadam must be 5 : 95 to 20 : 80. If the proportion
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of sand is low, the strength of the concrete tends to
be reduced and hence a sand/macadam weight ratio of 5 95
is suitable for a sidewalk pavement and a sand/macadam
weight ratio of higher than 10 90 is usually employed
for a light traffic road pavement. When the weight ratio
of sand/macadam is 15 : 85, the compressive strength
I of 115 kg/cm2 is typically obtained On the other
hand 7 if the proportion of sand is increased over the
foregoing upper limit, the water permeability of the
cement concrete construction becomes poor. also, a part
of the above-described aggregate can be replaced with
#6 macadam (having particle sizes of 13 mm to 5 mm) in
an amount of, preferably, 10 to 30% by weight. This case
is preferred in the point that the compressive strength
increases to some extend I = 125-140 kg/cm2) but is
accompanied by a disadvantage that the appearance of
the concrete is not good owing to the presence of the
large I macadam together with the I macadam.
The amount of port land cement in this invention
is 300 to 400 kg, preferably 320 to 370 kg per m of
the whole cement concrete mixture including water. If
the amount of the cement is over 400 kg, the strength
of the concrete is increased but the water permeability
thereof is reduced, which is unsuitable for the object
of this invention. On the other hand, if the amount
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of the cement is less than 300 kg, the strength of the
concrete becomes insufficient.
Also, a binder is added to the cement mixture in
an amount of 0.008 to 0.040 part by weight, preferably
0.015 to 0.03 part by weight per one part by weight of
the cement. As the binder, any binder which is ordinary
known as an additive for cement mortar can be used in
this invention. Examples of the binder which can be
used in this invention are natural or synthesis rubbers
such as styrene-butadiene rubber SIR nitril-butadiene
rubber (NOR), acrylic resins, epoxy resins, etc.
The binder is usually added as an emulsion thereof.
The foregoing amount of the binder indicates the amount
of the resin in the emulsion as solid component. When,
for example, a commercially available SIR series latex
binder (JAR Tomahawk Super I ~æ~ made by Japan
Synthetic Rubber Co., Ltd.; solid component of 45%) is
used in the above-described range, the improvement of
the bending strength of about lo Jo 60% is obtained.
If the binder is used over the above-describèd range,
the water permeability of the concrete is greatly reduced,
which is not preferred in this invention. Also, when
an acrylic binder (X-5142, trade name, made by ARC Co.,
Ltd.) is used, the improvement of the bending strength
of 60 to 90% is obtained. In the case of using an epoxy
Yore Jerk
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series binder, the improvement of the bending strength
of 20 to 40% is obtained but there is a disadvantage
that the epoxy series binder does not generally show
good workability.
The amount of water which is used in this invention
is 0.30 to 0.45 part by weight, preferably 0~35 to 0.40
part by weight per one part by weight of the port land
cement. If the amount of water is over the upper limit,
the water permeability of the concrete it reduced, while
if the amount of water is below the lower limit, it becomes
impossible to perform sufficient kneading of the cement
mixture.
Furthermore, in addition to the above-described
essential components in this invention, other additives
conventionally added to the cement concrete, such as
red oxide for coloring, etc., can be added thereto in
an amount of 3 to 5%.
The cement concrete construction in this invention
includes, in general, cement concrete constructions which
are required to have water permeability, such as pavements
for sidewalk, parking place, etc., permeable concrete
layers constructed under top soil for improving drainage,
and cast blocks used for the aforesaid purposes.
The feature of the water permeable cement concrete
constructions produced by the process of this invention
is its large void age. That is, a water permeable cement
concrete construction having a void age of 10 to 30%,
preferably 15 to 25% can be obtained according to the
process of this invention Therefore, the cement concrete
construction in this invention is superior Jo a water
permeable asphalt pavement in the points that the cement
concrete in this invention temporarily retains water
in the voids and thereafter the water permeates very
quickly through the concrete. Moreover, the water permeable
cement concrete construction produced by the process
of this invention has the advantages of not causing clogging,
change ox strength and water permeability thereof with
the passage of time, and melting at high temperature
US encountered in water permeable asphalt pavements.
Still further when small earth and sand carried by shoes
and tires of cars accumulate on the surface of the cement
concrete construction of this invention, they flow away
through the voids of the concrete by a rain and hence
cleaning of such earth and sand is unnecessary.
As to the water permeability coefficient, a water
permeable cement concrete construction having the water
permeability coefficient of the order of 10 1 to 10 cm/sec.,
typically the order of 10 1 to 10 3 cm/sec. is obtained
by the process of this invention. A void age of 20~ eon-
responds to the water permeability coefficient of the
order of 10 1 cm/sec. and a void age of 15% corresponds
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to the water permeability coefficient of the order of
cm/sec.
It must be especially mentioned that the water
permeable cement concrete construction produced by the
process of this invention has a sufficient strength for
enduring practical use while the concrete construction
shows the large void age and an excellent water permeability
as described above. According to the process of this
invention, a water permeable cement concrete pavement
having a compressive strength of 200 to 300 kg/cm to
weeks strength, cured in water maintained at 20C) and
a bending strength of 20 to 30 kg/cm2 (4 whelks strength,
cured in water maintained at 20C) are obtained.
A preferred example of the compounding ratio of
the cement concrete mixture in this invention is as follows;
weight ratio of sand : I macadam: 15 : 85,
cement: 350 kg/m3,
binder: 0.04 part by weight as a 45% emulsion,
based on the cement, and
water: 0.4 part by weight including water contained
in the emulsion, based on the cement.
Then, according to the second embodiment of this
invention, there is provided a process of producing a
cement concrete construction having the water permeability
coefficient of the order of 10 1 to 10 cm/sec. Considering
that a concrete having the water permeability coefficient
I,
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of the order of 10 1 to 10 cmJsec. has not hitherto
been known and the production of such a concrete has
been considered to be difficult, the above-described
advantage of this invention is utterly astonishing.
That is, according to the second embodiment ox this
invention there is provided a process ox producing
a water permeable cement concrete construction, which
comprises kneading a cement concrete mixture of 300 to
400 kg of port land cement per my of the cement Concrete
mixture and 0.005 to 0.1 part by weight, preferably 0.008
to 0.04 part by weight of a binder and 0.35 to 0.45 part
by weight of water per one part by weight of the cement,
the rest being an aggregate; said aggregate having the
particle size distribution that the weight percentage
of the particles passing through a 5 mm sieve is 50 to
100%, preferably 75 to 100%, the weight percentage of
the particles passing through a 2.5 mm sieve is 8 to
25%, preferably 8 to 18% when the water/cement weight
ratio is 0.35 Tao and 0 to 18%, preferably 5 to 15%
when the water/cement weight ratio is 0.~3 (exclusive)
to 0.45, end the weight percentage of the particles passing
through a 1.2 mm sieve is 0 to 6%; flowing or casing
the kneaded mixture thus obtained, and hardening the
mixture. In this embodiment, the term "per my of the
cement concrete mixture" is also concerned with a 50-called
theoretical density calculated excluding the voids in
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the mixture.
The cement concrete constructions prepared according
to the second embodiment of the process of this invention
has excellent water permeability and sufficient strength
and show very less change of the water permeability
and strength wit~lthe passage of time.
In this embodiment, the water/cement weight ratio
must be 0.35 to 0.45 and such an aggregate must be used
that has the particle size distribution that the weight
percentage of the particles passing through a 5 mm sieve
is 50 to 100%, the weight percentage of the particles
passing through a 2.5 mm sieve is 8 to 25%, and the weight
percentage of the particles passing through a 1.2 mm
sieve is 0 to 6% when the water/cement weight ratio is
0.35 to 0.43 or the particle size distribution that the
weight percentage of the particles passing through a 5 mm
sieve is 50 to 100%, the weight percentage of the
particles passing through a 2.5 mm sieve is I 18%'
and the weight percentage ox the particles passing through
a 1.2 mm sieve is 0 to 6% when the water/cement weight
ratio is 0.43 (exclusive) to 0.45. The aggregate which
is used in this invention may contain larger macadam
although the presence of the larger macadam reduces
the appearance of the cement concrete product produced
by the process of this invention. It is preferred in
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this embodiment of this invention that the weight percentage
of particles passing through a 0.6 mm sieve be 0 to
3%. The size of the sieve employed in this specification
is a nominal size. In the embodiment of this invention,
by employing of the aggregate having the particle size
distribution as very strictly defined as described above
and the relation of the water/cement weight ratio as
described above, the water permeability coefficient
of the order as high as 10 l to 10 cm/sec. can be obtained
and further a sufficiently high strength can be imparted
to the cement concrete.
It is utterly astonishing that a cement concrete
construction having a very high water permeability that
has never been expected is obtained using the materials
each known as a material for a cement concrete mixture
and by defining and combining the components for the
cement concrete mixture as described above according
to this invention.
The lower limit of the particle size (the percentage
of particles passing through each sieve) of the aggregate
is determined mainly by the requirement for the water
permeability For increasing the water permeability
of the cement concrete construction, it is necessary
to strictly control the proportion of the macadam having
fine particle sizes. Since a macadam usually used in
the field contain a considerable amount of fine sands
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in addition to the macadam of the nominal particle size range,
in the case of defining the particle size range in the second
embodiment of this invention, it is necessary to include
these sands for the calculation. Accordingly, it is
necessary to previously determine the proportion of the
fine sands by separating the fine sands by washing the
macadam and measuring the amount of the fine sands thus
separated.
On the other hand, the upper limit of the particle
size range (the percentage of particles passing through
each sieve) of the aggregate is determined mainly by the
requirement for the strength of the cement concrete construe-
lion. From the viewpoint of the practical use, the investiga-
lion was performed by paying attention to the 4 weeks
bending strength keyword in water kept at 20C), to obtain
a sufficient strength of higher than 20 kg/cm2, preferably
higher than 25 kg/cm2 while attaining a high water permeability.
The amount of the port land cement in the second embodiment
of the process of this invention is 300 to 400 kg, preferably
320 to 370 kg per my of the whole cement concrete mixture.
If the amount of the cement is larger than 400 kg, the
strength is increased by the water permeability being
reduced, which is unsuitable for the object of this invention.
On the other hand, if the amount of the cement is less
than 300 kg, the strength becomes insufficient.
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Furthermore, in this embodiment, a binder is added
to the cement concrete mixture in an amount of 0.005 to
0.1 by weight, preferably 0.00~ to 0.04 part by weight
per one part by weight of the cement. The binders as
described in relation to the first embodiment of this invention
can be used in the second embodiment.
The proportion of water in this embodiment of the
invention is 0.35 to 0.45 part by weight per one part by
weight of the cement. If water is used over the upper
limit, the water permeability of the cement concrete is
reduced, while if water is below the lower limit, it becomes
difficult to perform surf fishnet kneading.
It must also be especially mentioned that the water
permeable cement concrete construction produced by the
second embodiment of the process of this invention has
the sufficient strength while the cement Crusoe a sufficiently
large void age and an excellent water permeability as described
above. Accordingly to the second embodiment of this
invention, a water permeable cement concrete pavement having
a bending strength of higher than 25 kg/cm2 to weeks strength,
I) is obtained. The pavements
cured in water kept at 20
produced by the process of this invention can be used for
a sidewalks, parking places, playgrounds, etc., as well
as can sufficiently endure the use for a light traffic.
The invention will further be explained in the case
of applying the invention to pavements.
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It is necessary to determine the depth of the cement
concrete pavement in consideration of rainfall, rain Starr,
load applied to the surface of the pavement, water
retaining faculty of the pavement, supporting power of
the roadbed, water permeability of the roadbed 9 etch In
general, the depth of the pavement is about 10 cm for side-
walk portion, about 15 cm for parking places, play fields,
and about 15 cm to about 20 cm for light traffic roads.
Also, for reinforcing the pavement, ropes having high
tensile strength (e. g., glass fiber nets) may be installed
on the selection of the pavement.
At the execution of the water permeable cement concrete
construction according to this-invention, the above described
cement concrete mixture is mixed in a concrete plant equipped
with a conventional installation, transported to the spot
by means of a truck mixer or a damp truck, and is spread
uniformly and flatly on the surface of road or the roadbed
at a definite thickness by means of a finisher.
Then, the invention will be further explained by the
following examples.
Examples 1 and 2 and Comparison Examples 1 and 20
Using each of the aggregates having the particle size
distributions shown in Table 1, each cement concrete mixture
composed of 350 kg of port land cement per my (theoretical)
of the cement concrete mixture, 132.3 kg (excluding water
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contained in the following emulsion) of water, and 14 kg
of a binder emulsion (JAR Tomahawk Super, solid content 6.3
kg), the rest being the aggregate, was kneaded and after
casting the mixture, the mixture thus formed was hardened.
In each case the water/cement weight ratio was 0.40. The
water permeability coefficient and the 4 weeks bending
strength of each hardened product are shown in Table 1.
:
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Table l
._ _ _ _ _ _ _ ___ __
\ Weight of macadam (A) (B) (C)
. . \ passing through sieve .
\ 13 mm 5 mm 2.5 mm 1.2 mm
__ __ __
Example 1 lo 85 15 4 O . 40 8YlO-l 26.3
Comparison
Example l 100 85 4 -- 4 0.40 8.5xlO 1 19.0
Example 2 lo 85 20 4 0.40 1.3xlO 1 28.8
_. _ , _ ._
Comparison . -3
Example 2 lo 85 20 15 0.40 9.1xlO 30.5
_ , Jo _____ _ _
. . .
(A): Water/cement weight ratio
(B): water permeability coefficient (cm/sec)
(C): Bending strength (kg/cm2)
As is clear from the results shown in Table 1, the samples
in Examples l and 2 show an excellent water permeability coughs-
en and bending strength but the samples in Comparison Examples
1 and 2 are inferior in bending strength and/or water permeability.
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Example 3 and Comparison Example 3.
Using each of the aggregate having the particle size
distribution shown in Table 2, each cement concrete mixture
composed of 350 kg of port land cement per my (theoretical)
of the cement concrete mixture and 148.8 kg of water (excluding
water contained in the following binder emulsion and
15.8 kg of a binder emulsion (solid component 7.1 kg),
the rest being the aggregate, was kneaded, costed, and
hardened. Thus, the water/cement weight ratio was 0.45
in each case. The water permeability co-efficient and the 4
weeks bending strength of each hardened are shown in Table 2.
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Table 2
- . ;
\ Weight % of macadam (A) (B) (C)
\ passing through sieve
\ 13 mm 5 mm¦ 2.5 mm 1.2 mm
. .__~ _. _ .__ _
Example 3 100 85 10 4 0.45 4~5xlO 1 27.0
. _ .. _ __
Example 3 100 35 25 4 1 0.45 1.5~10 3 32.0
_
(A), (B) and (C) in Table 2 have the same meaning as in
Table 1.
As is clear from the results shown in Table 2, the sample
in Example 3 has an excellent water permeable coefficient and
bending strength as compared with the sample in Comparison
example 3.
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