AU732009B2 - A method of paving road with pervious cement concrete - Google Patents

Description

S F Ref: 413044

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Ik-Hyun Hwang 131-10 Songpa-dong Songpa-ku Seoul 138-170 REPUBLIC OF KOREA (SOUTH) Ik-Hyun Hwang Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia A Method of Paving Road with Pervious Cement Concrete

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The following statement is a full description of this invention, Including the best method of performing it known to me/us:- 5845 TITLE OF THE INVENTION a method of paving road with pervious cement concrete BACKGROUND-FIELD OF INVENTION This invention relates to a method of paving roads such as Snarrow or wide roads, driveways, highways and the like with cement concrete and, more particularly, to a method for paving roads with pervious cement concrete whereby a pavement is acquired wherein water drains through the pervious concrete but does not penetrate a stabilization layer or a base layer, thus water splash is reduced and noises on the road are absorbed by the pervious structure of the concrete without sacrificing the stability of the pavement.

oooo BACKGROUND-PRIOR ARTS Since roads are generally under repeated and varied loads or is stresses by vehicles, a careful design and construction should be made for all structural layers of pavement. When a road is paved with a pervious layer, it is required to take measures to prevent water passed through the pervious layer from arriving at base ground in order to stabilize the base ground.

erj There were two categories of concrete for permeability of water; over-all pervious concrete and drain-through asphaltic concrete. The over-all pervious concrete is a mixture of aggregate and cement, while the drain-through asphaltic concrete is using asphalt as a binder for aggregate.

The over-all pervious concrete in the prior art has certain inherent disadvantages; Firstly, drainage apertures formed therein permit water to pass through all the road structural layers, from the surface of pavement to roadbed, but the water passing through the iL drainage apertures deteriorates the base ground. Thus it cannot be applied to a pavement whose base ground should be under stable condition.

Secondly, since forming voids is a main purpose for construction of the over-all pervious concrete which is developed as a pavement for protecting underground water resources, the pervious concrete includes #4 size aggregate in the amount of at least 20% of total aggregate, for example, up to 40% in 13mm pervious concrete. #4 size of aggregate is so evenly distributed in the total aggregate that the size of Sthe voids does not exceed 3mm, thus the voids will be easily plugged with soils and dusts.

0*00 Thirdly, surface fracture is a problem with over-all pervious 00..

concrete under heavy load since any separate reinforcement treatment is not considered. The over-all pervious concrete without any separate reinforcement has an inherent problem that structural fragility resulting from drainage apertures causes break down of the structure due to repeated loads and stresses by vehicles.

Drain-through asphaltic concrete of the prior art also has some disadvantages as follows; The drain-through asphaltic concrete contains asphalt as a binder to bind aggregate together. The formation of the drainage apertures is related to the ratio of amount of I) aggregate and asphalt contained in the concrete. This limits the amount of the asphalt used around 4-5% of the total concrete composition, and thus binding strength between the asphalt and aggregates is relatively small.

The asphalt used in the porous asphaltic concrete as a binder melts at the higher temperature in summer so that soil and particles are adhered to the asphalt to plug the drainage .apertures.

At the same time, the pavement sinks under repeated heavy loads by vehicles due to the structure of drainage apertures O and grooves which deteriorates evenness of road are formed along the passage line of wheels of vehicles.

It is therefore desirable to provide a method of paving a road with pervious cement concrete which satisfies the requirements prescribed in road-concerning regulations such as compressive strength, bending strength and like in addition to its permeability.

It is further desirable to provide a method of paving roads with pervious cement concrete that can maintain drainage capability by itself without permanent plugging of the drainage apertures and can be constructed conveniently with mechanical equipment to shorten the period of construction.

to It is further desirable to provide a method of reinforcing the surface strength of the pervious layer and enhancing the binding strength between the pervious layer and a lower concrete layer.

It is the object of the present invention to substantially overcome or at least ameliorate one or more of the disadvantages of the prior art or to meet one or more of the is above desires.

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e •Qooo4 [R:\LIBLL] 10591 .doc:caa SUMMARY OF THE INVENTION Accordingly, the present invention provides a method of paving a road with an impervious lower layer and pervious surface layer comprising the steps of: applying, onto a base layer or a lean concrete layer, a concrete mixture comprising cement, water and aggregate, the particle size of said aggregate being up to in diameter, and the portion of the aggregate below 5mm in diameter being 25 to of the total aggregate, the mixture having a slump value in the range of 0 to 3 cm to form an impervious lower layer with a thickness of 5 to 25 cm; pressing said concrete mixture of the lower layer with means for pressing a concrete layer; spraying water over said impervious lower layer; applying onto said impervious lower layer, a concrete mixture comprising cement, water and aggregate, the particle size of said aggregate being up to 40mm in diameter, and the portion of the aggregate below 5mm in diameter being below 10% of the total aggregate. The mixture having a slump value in the range of 0 to 4 cm and having a porosity in the range of 15% to 30% to form a pervious surface layer; said concrete mixture of the pervious surface layer with means for pressing a concrete layer; and spraying aqueous epoxy resin or aqueous acryl type resin onto said pervious surface layer.

•o *o [RA\LIBLL] 10591 .doc:caa Water, more particularly, a mixture of water, cement and fluidizing agent is preferably sprayed over the lower concrete layer and the pervious concrete layer is then applied onto the lower concrete layer within one hour after the lower concrete layer is applied.

The mixture desirably consists of one part of water, 0.1 to 0.5 part of cement and less than 0.005 part of fluidizing agent. The mixture may further include 0.1 to 1 part of methanol so as to enhance coloration and dispersion of pigment.

The lower layer preferably has a cross slope in the range of 2 to 7% from the center of the road to the each side of the pavement.

A concrete mixture as a lower desirably consists of 80 to 140kg/m 3 of cement, 950 to 1550kg/m 3 large aggregate at size between 5mm and 40mm, 470 to 1000kg/m 3 of small aggregate smaller than 5mm in the diameter, and less than 2.0kg/m 3 of concrete water-reducing agent. The slump value of the mixture should be in the range of 0 to 4cm.

Is In the preferred embodiment, pressing concrete layers to achieve compacting rate over 90%, more preferably over 95%, is required.

Instead of spraying reinforcement material, water can be strongly sprayed over the pervious concrete layer, which allows cement to penetrate into voids of the concrete and strengthen its binding force for aggregate, before the pervious concrete is dried.

ao *eoc *oo FR I T .T .1.105 I 1 donrc in BRIEF DESCRIPTION OF THE DRAWINGS A preferred form of the present invention will now be described by way of example s with reference to the accompanying drawings, wherein: Fig. I is a cross-sectional view illustrating a conventional permeable pavement; Fig. 2 is a cross-sectional view illustrating a permeable concrete pavement; Fig. 3 is s cross-sectional view of a general highway constructed by a conventional method; and Fig. 4 is a cross-sectional view of a pervious road constructed by a method of the present invention.

[R:\LIBLL]10591.doc:caa DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS If not noted particularly, part and percentage indications of consituents are based on weight thereof.

Pervious layer The pervious layer having a thickness in the range of 3-15cm allows water pass through its drainage apertures. To attain the objects of the present invention and at the same time to satisfy the requirements prescribed in road- concerning regulation such as compressive strength, bending strength and the like and concurrently to maintain its drainage capability without a problem of permanent plugging of the drainage apertures, the following conditions for a pervious layer should be considered: .°eoe e Formation of voids (drainage apertures).

Porosity, size of voids and distribution of voids by :sizes.

Distribution of particle size of aggregate satisfying (b) o The porosity of the concrete mixture is controlled by the @0 proper ratio of cement volume, aggregate volume, and water volume. Various degrees of porosity are achieved depending o *upon the variation of these volume ratios. The mixture of the present invention is formed in conformity with the following requirements: The aggregate is compacted with compacting ratio more than The cement paste used as a binder for particles of aggregate together is formed in a paste form in such an amount, that it merely surrounds the surfaces of particles of the aggregate.

The voids between the large particles of the aggregate are filled with the smaller particles of aggregate.

The porosity is about 15-30%.

0 The size and distribution of voids are at least of voids larger than 3mm and at least 10% of voids larger than To meet both the requirements and the slump value of the pervious concrete mixture consisting of aggregate, cement and water is zero to about 3cm.

The particle size of the aggregate is directly related to the values given by and In the present invention, the particle size of the aggregate is up to *'*Small aggregate less than 5mm in diameter included in the aggregates should be less than 10% of the total aggregate.

Roller pressing is available since the slump of the cement concrete would be approximately zero, which enables construction work on a large scale and thus reduces the period of construction.

In and the portion of voids larger than 3mm in diameter is 70% of all voids so that the voids may not easily be plugged with soils and dusts. The portion of voids larger than 10mm in diameter is at least 10% so that vacuum state may arise when rainwater pass the voids. Vacuum formed in the larger voids gives adsorbtion force to adjacent plugged voids to restore drainage.

The surface of the drainage layer contains the drainage apertures. Thus a reinforcement of the surface layer is needed L0 to prevent its destruction due to heavy impulsive load by vehicles even if compressive strength and bending strength of the layer is sufficient at the time of curing.

The reinforcement material for the surface layer is EVA aqueous epoxy resins or aqueous acryl resins and aqueous I asphalt. The reinforcement material is sprayed on the surface of the pervious layer to be evenly absorbed into small voids below 0.5mm in diameter to reinforce the strength of the i. pervious layer.

S. It is sufficient to introduce the reinforcement material into the pervious layer as thick as approximately 5cm from the top surface, but the absorbtion of the reinforcement material into the entire layer is also desirable.

The porosity in relation with the size of the void can be measured with regard to the voids having diameters above 3mm, Sconcrete sample is cut with a cutting machine and straight line is drawn on the cutting plane to calculate an indirect porosity a from the total length and the length of the portion lined. Another indirect porosity P for the voids above 3mm in diameter is calculated from the portion not lined.

Indirect porosity a [(the total length the length of a portion lined) the total length] x 100 Indirect porosity 3 for void having a diameter above 3mm [sum of the length not lined in voids above 3mm in diameter >0 (the total length the length of a portion lined)] x100 the lower impervious layer The non-pervious layer is applied to stabilize the base by preventing water passed through the pervious layer from penetrating into the base ground.

1 The non-pervious layer of the present invention refers to the lower impervious concrete layer in the road sectional structure.

The particle size of the aggregate in the lower concrete layer (the thickness is 5-25cm thick) is below 0 Particulate sand below 5mm is included inthe aggregate as the eo*"o' ratio of 1/3-~1 based on agregate above 5mm. The mixture is prepared in such a manner that the slump value may be in the range of 0-4cm in and s the requirements of compressive strength and bending strength in may be satisfied. The compacting rate after pressing is at least 90%. Since the slump value is 0-4cm, the pervious layer can be applied immediately after pressing and a machinized construction work is feasible with roller pressing. A dense structure is formed by small particles contained in the concrete layer.

The cross slope about 2-7% of the lower concrete layer help water drain at high velocity to increase the instantaneous vacuum state.

I0 Reinforcement of binding strength between the lower concrete layer and pervious layer The period of construction can be shortened because the pervious layer can be applied immediately after pressing of the lower concrete layer. After pressing the lower concrete 5 layer, water can be sprayed over the surface of the lower concrete layer slightly dripping wet and the pervious layer is applied on the lower concrete layer.

The bonding strength between the lower concrete layer and pervious layer becomes higher by an instaneous hydration of the cement paste.

When the surface of the lower concrete layer gets dried which ooooD is about 1 hour after pressing of the concrete layer, the adhesion cannot be strengthened by simply watering the concrete layer. Thus, the reinforcement of the bonding strength between the layers is achieved by spraying a mixture of water, cement and emulsifier over the lower concrete layer and then applying the pervious layer thereon.

To increase bonding strength between the layers, minimum of water is spraye. Fluidizing agent is desirably added to the mixture to increase the degree of dispersion of the cement.

The cement paste enters the voids in the pervious layer, which also increases the bonding strength between the lower concrete layer and pervious layer.

The lower concrete layer and pervious layer are constructed in the following procedures and composition ratio.

Composition ratio and application procedure of the lower o concrete layer Xt" A mixture is prepared from 80-140kg/m 3 of water, 250-400kg/m 3 of cement, 950-1,550kg/m 3 of aggregate, 470-1,000kg/m 3 of sand below 5mm in diameter, and less than 2.0kg/m 3 of concrete water-reducing agent. The slump value is in the range of 0-4cm.

It takes about 30 days to cure the conventional concrete.

However, the pervious layer can be applied immediately on the I0 impervious concrete according to the present invention without a separate time for curing due to its slump of 0-4cm, thereby drastically reducing the period of construction work.

To enhance a compacting rate up to at least 90%, the lower concrete of the mixture as described above is tamped by a roller and the like to have a compacted thickness between and 25cm. The lower concrete has the compressive strength of 240kg/m 2 and the bending strength of 40kg/m 2 which are all above the limited values, at least 180kg/m 2 and 28kg/m 2 according to the regulations respectively. The tamping rate is more than 90%, more preferably, above Reinforcement of the bonding strength between the lower (0 concrete layer and pervious layer Where the lower concrete layer contains a lot of moisture on the surface thereof (usually within 60 minutes after a pessingcompacing), only water less than 1 kg per unit square meter of the surface must be sprayed. If the surface of the lower concrete layer is almost dried (usually after 60 minutes after pressing), there must be sprayed a reinforcement composition prepared by mixing water, cement, fluidizing agent in the weight ratio of 1 0.1-0.5 0.005 or less, in the amount of 0.1-1 kg per unit square meter of the surface. This induces the active hydration of the cement paste incompletely mixed to reinforce the bonding strength between the lower concrete layer and pervious layer.

Composition ratio and application procedure of the pervious concrete layer The pervious concrete layer is applied over the water-sprayed lower concrete layer within about 60 minutes. An mixture is prepared by mixing 1m 3 aggregate 300-450kg/m 3 of cement, 140kg/m 3 of unit quantity, less than 2.0kg/m 3 of concrete water reducing-agent, inorganic pigment for coloring in the amount of below 10% by weight of cement, and as a mixing polymer, selected from the group consisting of aqueous acryl resin, EVA, aqueous epoxy, SBR latex, or fluidized asphalt in the amount of below 20% by weight of cement. The slump is in the range of 0-5cm. The compacting rate is at least 90%, more t0 preferably, at least 96% to have a compacted thickness between 3 and The pervious concrete layer the compressive strength of above 240kg/m 2 and the bending strength of at least 40kg/m 2 of the pervious concrete layer of the invention, exceeds 180kg/m 2 and 28kg/m 2 the criteria for a road concrete layer, respectively.

The cement content is between 300 and 450kg/m 3 When it in 0 0* over 450kg/m 3 a sponge effect occurs during pressing with a roller. The cement content below 300kg/m 3 reduces the compressive strength to 180kg/m 3 or less.

6 The aggregate used has an absolute dry specific gravity above 2.50 and exhibits the wear rate of 30% in the Los Angeles wear abrasion test. The particle size of larger aggregate is less than The porosity of the aggregate is in the range of 35-55% according to compacting test standards. If less than 35% in the tamper test, the porosity of the pervious concrete becomes below 15% and the drainage coefficient is less than after the polymer is sprayed on the concrete. When the porasity in above 55%, the strength of the pervious concrete Sis weakened even with a lot of cement and the application of the concrete gets more difficult due to a sponge effect caused by an excessive use of the cement.

The aggregate should have the wear rate below 30% in the Los angeles abrasion test. With the abrasion 30% or more, the concrete tends to be broken to deteriorate the pervious of water and shorten the duration of the road.

Reinforcement for the strength and durability of the pervious concrete layer A reinforcement solution is sprayed over the pervious concrete 5 layer down to the lower concrete layer to enhance the strength oo ~and durability of the pervious concrete layer. The solution in prepared by mixing water, cement or plaster, fluidizing agent, inorganic pigment, one or two polymers selected from 6 the group consisting of EVA aqueous epoxy aqueous and acryl d; type resin, and methanol in the weight ratio of 1 1-0.2 0.005 or less 0.005-0.05 0.15 or less 1 or less. The addition of the mixture desiralily reduces the porosity of the pervious concrete from about 18% to about 15%. The concrete after spraying the mixture is cured by covering the concrete aS layer with curing cloth such as plaaaastic film for about 1 day to prevent the vaporization of moisture.

The composition is applied preferably within 3 hours or in one day after the pervious concrete layer is pressed. The durability of the pervious concrete may be deteriorated when the solution is sprayed before 3 hours after pressing, but the Smixture can be applied after the concrete is firstly cured which is one day after pressing.

As another embodiment to of the strength and durability of the pervious concrete layer, water is strongly sprayed over the wet surface of the pervious concrete layer pressed instead of applying the mixture as described above. Spraying water cleans out the cement paste attached on the surface of the aggregate, permitting the concrete paste to penetrate into the voids to increase the bonding strength between the aggregates. This exposes the aggregate out of the surface to show a good natural appearance but makes the aggregates fractured out of the .i surface. It should be noted that the use of water for a reinforcement referred to above is particularly suitable for roads, under relatively light load or squares on which small vehicles run.

;0 (Example) The present invention is applied onto preconstructed road which is 50m long and 9m wide with 3m widch shoulders on both sides being 3m in width. The road consist of having auxiliary lower and a lean concrete layer. A lower layer in applied as a3 thick as 20cm on the road and the pervious concrete is applied over the lower concrete lay by about 10cm thick. The road shoulder is formed by applying the pervious concrete of thick on the traditional concrete layer of 5cm. The color is light green and a perforated tube is provided in the border side of the road. There are provided with the following equipment and mixtures of concrete [Equipment: finisher for laying asphalt concrete (4.5cm in width), a tandem roller of 6-8 tons, a tire roller of 10-12 tons, a remicon plant, a dump truck] The compositions for the lower concrete layer and pervious concrete layer used in this example is an follows; DIV constituents(kg/m 3 unit weight of agge retard consti aggre ceme aggregate er tuent Mater water sand gate i 3 als nt 25mm materi (kg/m als 19-5m als als A lower layer 32.4 28 110 340 569 1,492 0.85 2,511 concrete pervious ero 30.9 0 116 375 1,550 0.94 2,042 concrete 9 .9 9.

9 1r 0, 9 (1 (W/C is the ratio of water to small aggregate) cement, S/A is the ratio of Step 1: A mold sheet was first provided as high as above over a pavement auxiliary lower, lower and lean concrete above. By means of the finisher, the lower concrete was IS applied from one side of the road to the other side so that a cross slope may be 3% and the thickness may be considering compacting rate. It was then pressed with the tandem roller to have above 96% density.

Step 2: After 60 minutes or more after pressing, mixture was 6 prepared by mixing water, cement and fluidizing agent in the weight ratio of 1 0.3 0.003 and applied over the lower concrete by 0.3 kg per unit square meters to fill the surface voids remaining on the lower concrete.

Step 3: Immediately after the application of the mixture, the l' pervious concrete was applied by using the finisher for asphalt pavement and with tandem and tire rollers to have the maximum compacting density of above 96%.

Step 4: A reinforcement material to increase the strength and durability of the concrete was prepared by mixing water Is cement, fluidizing agent, green pigment, and aqueous epoxy in the weight ratio of 1 0.2 0.002 0.02 0.02. The mixture (a was applied across the surface of the pervious concrete as much as 4.2kg per unit square meter to soak into the lower concrete layer. The concrete layer was covered with curing O cloth such as plastic filn for about one day to the mixture S...may be solidified without vaporization of moisture therein.

The porosity of the pervious concrete decreased from 18% to by application of the mixture.

Step 5: After two days passed while watering on the concrete Slayer for natural curing as required in a known method. Cut lines were installed on the layer and fillers were stuffed in the cut lines. The layers were cured for 28 days.

The pavement work for the road shoulder was made in the same procedures as an steps 1 to A test of the finished road shows the results as shown in Table 1, for the porosity, compressive strength, compacting rate and bonding strength.

<Table 1> compres DIV Poro bending permeab compa Ssive bonding indirect sity strength ility cting color TSTstrength strength porosity TEST (kg (kg/c f) (cm/sec) rate (kg base abuting 35% for ortion over 3mm tamping 4% 334 49.2 98.0 o i o is voids concrete not loose 27% for under impact previous19.4 327 48.9 4.2x 96 light but other over concrete green portion voids is destroyed at least abutting S70% for portion above 3mm standard at at at at at- should o limited voids (expectedleast least least least least l not vo value) 15% 270 45 10 90 sample be looseat least 10% for under over impact voids site method KSF KSF permeab KSF naked KSF naked eye y ruler of test 2505 2506 ility 2312 eye S_ test a.

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a *a ra..a (The compressive and bending strengths are measured after the application of the surface materials.) As shown in Table 1, the layers exhibits good strength and permeability, and an excellent durability due to a firm adhesion between the lower impervious concrete and pervious concrete layers. Additional curing of the lower concrete layer is not required thus reduces the period of construction and curtails the cost of construction.

It will be apparent to those skilled in the art that various modifications and variations can be made in a method of paving roads with cement pervious concrete without departing from the spirit or scope of the invention. The present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their 5' equivalents.

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Claims (7)

1. A method of paving a road with an impervious lower layer and a pervious surface layer comprising the steps of: applying, onto a base layer or a lean concrete layer, a concrete mixture comprising cement, water and aggregate, the particle size of said aggregate being up to 40mm in diameter, and the portion of the aggregate below 5mm in diameter being 25 to 50% of the total aggregate, the mixture having a slump value in the range of 0 to 3 cm to form an impervious lower layer with the thickness of to 25 cm; pressing said concrete mixture of the lower layer with means for pressing a concrete layer; spraying water over said impervious lower layer; applying onto said impervious lower layer, a concrete mixture comprising cement, water and aggregate, the particle size of said aggregate being up to 40mm in diameter, and the portion of the aggregate below 5mm in diameter being below 10% of the total aggregate, the mixture having a slump value in the range of 0 to 4 cm and. having a porosity in the range of 15% to to form a pervious surface layer; pressing said concrete mixture of the pervious surface layer with means for pressing a concrete layer; and spraying aqueous epoxy resin or aqueous acryl type resin onto said S;previous surface layer.

2. The method as defined in claim 1, wherein the distribution of particle size of said aggregate is controlled so that the concrete mixtures have a slump value of zero both in said impervious lower layer and in said pervious surface layer.

3. The method as defined in claim 1 or 2, wherein said impervious lower layer has a cross slope in the range of 2 to 7 from t the center of the road to each side of the road.

4. The method as defined in claim 1 or 2, wherein cement and fluidizing agent are added to and mixed with said water to be sprayed over said impervious lower layer.

The method as defined in claim 4, wherein said mixture for spraying over the impervious lower layer consists of one part of water, 0.1 to 0.5 part of cement and less than 0.005 part of fluidizing agent based on said water.

6. The method as defined in claim 4 or 5, wherein said mixture is for spraying over the impervious lower layer is sprayed by the amount of 0.1 to 1 kg per square meter of the surface of said impervious lower layer.

7. A method of paving a road, said method being substantially as hereinbefore described with reference to Fig 4 of the accompanying drawings. Dated 13 February, 2001 Ik-Hyun Hwang is Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON 0*2 So S* 23 [R:\LIBLL]46044.doc:caa