DE9417821U1 - Drain concrete - Google Patents

Description

Hoechst Aktiengesellschaft for Cash-AIßert

94/K201G -1- 4.11.1994

WL-Dr. Fe-ef

Drain concrete

The innovation concerns a noise-absorbing and water-permeable concrete, so-called drain concrete.
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In recent years, the population's environmental awareness has increased considerably, including with regard to noise pollution. Due to the sharp increase in traffic volumes, particularly on motorways, the issue of traffic noise is now playing a central role.
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The causes of traffic noise can be found in:

- Vehicle drive (engine noise),

- Rolling of the tires on the road surface (rolling noise).

The rolling noises mainly have the following causes:

a) Radial tire vibration:

- Impact of the tread elements on the road surface,

- Compression of the tyre tread as a result of the surface texture,

b) Resonance of the air between tyre and road surface:
- pipe resonance,

- Helmholtz resonance,

- "Air Pumping",

c) Adhesion:

- Tangential vibrations as a result of "stick-slip" movements,
- Tearing off of profile elements,

d) Collision of profile elements:

- Water film and acceleration of water drops (only in wet
road surface).

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The legislature has taken the increased noise levels into account with the "Guidelines for Noise Protection on Roads - 1990 Edition - RLS - 90" and with the "16th Ordinance on the Implementation of the Federal Emissions Control Act" (Traffic Noise Protection Ordinance - 16th BImScH V). To achieve these goals, the following measures are still mainly taken:

The noise is reduced at the source, i.e. the vehicle or its tires.

The sound propagation areas are protected by protective walls and

would be limited.
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Recently, efforts have also been made to reduce the propagation of noise from the road surface. The following have a major influence on the noise emission of a road surface:

- the mega texture (texture wavelength 50 - 250 mm),
- the macrotexture (texture wavelength 1-50 mm),

- the acoustic impedance (sound absorption).

Sound absorption occurs in a porous road surface. The absorption should take place in the frequency range of the human ear and ideally in the sensitive range between approx. 200 and 2000 Hz. The acoustic impedance of an open-pored road surface is determined by:

- the porosity (accessible void content),

- the flow resistance (permeability),

- the structural factor (pore structure in the accessible cavity, connection of the pores to each other),

- the layer thickness.

In practice, thick layers of surfaces with many cavities have proven to be effective, for example drainage asphalt or "whisper asphalt". With open-pored or cavity-rich road surfaces, it is possible to achieve

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the noise level can be reduced by up to 3 dB(A). However, porous asphalt surfaces are currently expected to have a maximum lifespan of 6 years, meaning that such porous surfaces must be renewed much more often than conventionally dense asphalt surfaces.
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Concrete has the advantage over asphalt of a much longer service life, meaning that concrete surfaces require less frequent repairs. The aim is therefore to equip concrete surfaces with appropriate noise-reducing properties (Intron report No. 94 229, Porous Concrete - Laboratory tests, pages 11-12). At the same time, however, the positive properties of concrete, such as high durability, should be retained.

It is generally known that concrete can be modified with plastics to improve its application properties. According to DE-A 42 12 325, concrete modified with a styrene/acrylate dispersion produces water-impermeable molded bodies. However, to ensure sufficient water permeability and high sound absorption, the porosity and structure factor of the concrete should be as high as possible.

Previous attempts to produce plastic-modified porous concrete have shown that void content and strength show opposing tendencies. The higher the void content, the lower the strength of the road surface. At the same time, with a void content that is acoustically effective, the strength was found to be insufficient for a road surface subject to high loads.

In previous tests, the connection between the acoustically effective road surface and the sub-concrete has also proven to be insufficiently durable (Intron report No. 94 229, Porous Concrete - Laboratory tests, page 73).

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The aim of this innovation was therefore to develop a drainage concrete that achieves the required noise reduction in the road surface, has good adhesion to the subsurface and has a long service life.

The task was solved by adding an anionic styrene/acrylate dispersion, whose minimum film formation temperature (MFT) is above the hardening temperature of the concrete mix, to concrete with a narrow grain size distribution.

The subject of the innovation is a drainage concrete with 10 to 35 vol.% void volume, containing a hydraulic binder from the cement series and a polymeric binder in the form of an anionic styrene-Zacrylate copolymer, the minimum film forming temperature (MFT) of which is above 30 ^° C, as well as aggregates with grain sizes in the range of 2 to 10 mm.

The proportion of the polymeric binder is preferably 5 to 40% by weight, in particular 10 to 20% by weight, based on the hydraulic binder. The MFT of the polymeric binder is preferably 33 to 60 ^° C, in particular 35 to 50 ^° C.

According to the innovation, particularly suitable for use in drainage concrete are, for example, aqueous plastic dispersions based on anionic copolymers of the following monomers:

(a) 51 to 60 parts by weight of styrene and optionally methyl methacrylate,

b) 40 to 45 parts by weight of (C ₂ -C ₈ )-alkyl acrylate or (C ₄ -C ₈ )-alkyl methacrylate,
c) 2 to 4 parts by weight of &sgr;,&bgr;-unsaturated carboxylic acids,

where the sum of a) + b) + c) = 100 parts by weight of copolymer must result and these copolymers additionally, each based on 100 parts by weight of copolymer from a) + b) + c),

d) 0 to 2 wt.% ethylenically unsaturated comonomer units containing sulfonic acid groups or phosphoric acid groups and

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e) 0 to 2% by weight of ethylenically unsaturated comonomer units with organosilicon radicals which may be reactive or, as a partial or complete replacement of the organosilicon comonomer units,

f) 0 to 2 wt.% of epoxysilanes mixed into the aqueous plastic dispersions,

where the sum of e) + f) is a maximum of 2 wt.%,

contain.

Particularly preferred plastic dispersions according to the invention are, for example, those based on anionic copolymers with the following composition:

(a) 52 to 55 parts by weight of styrene,

b) 41 to 44 parts by weight of n-butyl acrylate,

c) 2 to 3 parts by weight of acrylic acid and/or methacrylic acid,

d) 0.5 to 1.5 parts by weight of ethylenically

unsaturated comonomers,

e) 0.5 to 1.5 parts by weight of ethylenically unsaturated comonomers with

organosilicon residues which may be reactive or, as partial or complete

Replacement of organosilicon comonomers,

f) 0.5 to 1.5 parts by weight of epoxysilanes mixed into the aqueous plastic dispersions,
where the sum of e) + f) is a maximum of 2 parts by weight.

The chemical resistance of the hardened concrete can be further improved when the plastic dispersions are used in concrete mixtures in accordance with the innovation by adding comonomer units with organosilicon residues in the anionic copolymers or by adding epoxysilanes to the aqueous plastic dispersions in accordance with the innovation.

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As emulsifiers, the dispersions preferably contain conventional ionic and, in particular, anionic and/or conventional nonionic surfactant compounds in the amounts usual in emulsion polymerizations. For example, the plastic dispersions contain as emulsifiers, based in each case on the anionic copolymer, 0.3 to 2% by weight, preferably 0.5 to 1.5% by weight, in particular 0.6 to 1% by weight, anionic emulsifiers, preferably emulsifiers containing sulfo groups, in particular alkali salts of sulfuric acid half esters of oxyethylated alkylphenols, and 1 to 5% by weight, preferably 1.5 to 3% by weight, in particular 2 to 2.5% by weight, nonionic emulsifiers, preferably alkylphenol polyglycol ethers, in particular nonylphenol polyglycol ethers or tributylphenol polyglycol ethers with preferably 15 to 50 ethylene oxide units.

Hydraulic binders that can be used in accordance with the innovation are preferably all inorganic substances in amorphous form that can react with water to form cement. Preference is given to all types of cement that are specified in DIN 1164, in particular blast furnace cement and Portland cement, as well as mixtures of these types of cement with substances that can supplement or improve the effect of cement, preferably fly ash from coal combustion processes or from the silicon production process.

The proportion of the hydraulic binder is preferably 10 to 30 wt.%, in particular 15-25 wt.%, based on the drainage concrete.

The aggregates to be used according to the innovation preferably have a grain size in the range of 4 to 9 mm, in particular 5 to 8 mm. A grain size distribution that is as uniform as possible is particularly preferred.

Suitable aggregates include, for example, fine chippings 100%, split 100%, round grain 100% and mixtures of these aggregates.

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The proportion of the aggregates is preferably 65 to 85% by weight, in particular 70 to 80% by weight, based on the drainage concrete.

If required, the drain concrete can contain additional agents, such as concrete plasticizers, flow agents, retarders, thixotropic agents, stabilizers.

The drainage concrete according to the innovation is produced by mixing the hydraulic binder, the polymer binder, the aggregates and, if necessary, other additives with water.
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The water-cement ratio (W/C ratio) is 0.16 to 0.40, preferably 0.20 to 0.30.

According to the innovation, the void volume of the drainage concrete is preferably 15 to 30 vol.%, in particular 20 to 25 vol.%.

The drainage concrete according to the innovation preferably has, after 28 days after production, a concrete compressive strength of > 25 N/mm ² , in particular > 30 N/mm ² , a flexural tensile strength of > 5.5 N/mm ² , in particular > 6.5 N/mm ² , a splitting tensile strength of > 2.5 N/mm ² , in particular > 3 N/mm ² , a surface tensile strength of > 3 N/mm ² , in particular > 3.5 N/mm ² , and a static ε-modulus of < 20,000 N/mm ² , in particular < 15,000 N/mm ² .

Due to its special properties, the new drainage concrete is suitable for producing a water-permeable and noise-absorbing road surface.

To do this, a bonding bridge can first be applied to a hardened sub-concrete and the drainage concrete can be applied directly to the bonding bridge. If

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the sub-concrete is still fresh, the drain concrete can be applied directly to the fresh sub-concrete. With this procedure, the bonding bridge can be omitted. By modifying the drain concrete and, if necessary, the bonding bridge with the anionic styrene/acrylate copolymer, 5, sufficient adhesion to the substrate is achieved.

FIG. 1 shows a top layer of drain concrete on a sub-concrete. The porosity and the relatively narrow grain size distribution of the drain concrete can be clearly seen.
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FIG. 2 shows a road structure consisting of sub-concrete, bonding layer and drainage concrete.

The position numbers shown in FIG. 1 and FIG. 2 mean:
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1 Drain concrete (top concrete) 2 Bonding bridge 3 Ceiling concrete (sub-concrete) 4 Base layer 5 Single grain concrete 6 drainage 7 seal

The new drainage concrete in the road surface leads to a reduction in noise emissions, preferably by at least 3 dB(A), in particular by at least 4 dB(A).

The new drainage concrete is sufficiently permeable to allow rainwater to drain away without forming puddles.

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Examples Production of drainage concrete

The drainage concrete is produced in a stationary or mobile mixing plant, a forced mixer with a good mixing effect. Depending on the quality of the mixing effect, the mixing time is at least 60 seconds after all components have been added. The following recipe is used to produce the drainage concrete.
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1495 kg/m ³ fine chippings, 5-8 mm,

350 kg/m ³ cement ®PZ 35 S ₁

(Portland Cement, Dyckerhoff),
53 kg/m ³ water,

70 kg/m ³ ® Mowilith LDM 6880,

(Styrene/butylacrylate dispersion, Hoechst),
Mix weight: 1968 kg/m ³ ,
W/C ratio: 0.25.

After adding the components of fine chippings, cement and water, mix for about 20 seconds, then add the dispersion. The mixing time after adding the dispersion is at least 60 seconds. This recipe produces a drain concrete with about 20% accessible void volume.

₉ m I ·· ■······

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Production of a road surface

Preparation of a bonding bridge

The bonding bridge is produced in an ultra mixer (1000-1500 rpm), for example U 80 (Putzmeister, Aichtal). The mixing time with this mixer is approx. 30 seconds.

The mixture is produced by adding the raw materials in the following order:

12.5 kg water,

7.5 kg dispersion Mowilith LDM 6880,

0.2 kg concrete plasticizer ®BV 1

(melamine resin, additive),

50.0 kg cement PZ 35 S,

W/C ratio: 0.33

The components water, dispersion and concrete plasticizer are weighed according to the instructions and premixed in the ultra mixer for approx. 5 seconds. After the premixing phase, the cement is added. After all components have been added, mixing takes place for a maximum of 20 seconds.

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Laying the sub-concrete

The sub-concrete is laid in the intended thickness as classic road concrete using one of the known production techniques, for example slipform pavers or rail pavers. The surface is given its final surface texture by smoothing and creating a texture with the help of a jute cloth. The post-treatment of this concrete is carried out with damp cloths and/or foil. The surface adhesion strength of the sub-concrete must be at least 3 N/mm ^2. If the above test value is not achieved, the zone of the sub-concrete close to the surface must be improved by suitable surface treatment measures, for example shot blasting. Transverse and longitudinal joints in the sub-concrete are formed conventionally in accordance with the applicable rules and regulations, for example joint profiles. The doweling and anchoring of the individual slabs takes place in the middle of the sub-concrete. The spacing as well as the number and dimensions of the dowels and anchors are carried out in accordance with the applicable rules and regulations.

Application of the bonding bridge

The freshly prepared bonding bridge is applied to the moistened, stable concrete substrate by hand or by spraying. The application quantity is on average > 1000 g/m ² depending on the roughness of the substrate. If the bonding bridge is applied by hand, the bonding bridge is brushed in with a hard broom.

Alternatively, the bonding coat is applied mechanically, for example with a spray boom or a spray ramp or individual spray nozzles. Due to the limited open processing time, the bonding coat is only applied immediately in front of the road paver.

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Installation of the drainage concrete

The drainage concrete is installed in the freshly laid bonding layer using a road finisher with a high-pressure compaction screed and a concrete strip. The finisher, which has an automatic height leveling system, is guided along a wire to achieve the required installation thickness and optimal evenness in width. The installation height can also be taken from the surface using a sliding shoe. The drainage concrete already has the finished surface directly behind the finisher. Due to the high stability of the installed drainage concrete, it can be treated immediately. The surface is covered with damp cloths, for example jute or ®geotextile, and/or foils (PE foil, thermal foil). The drainage concrete covering layer can be produced with and without dummy joints. If longitudinal or transverse joints are planned, only a 3 mm notch cut is made (cutting depth > 30% of the installation thickness). The notch cut is not cast in the drainage concrete. The longitudinal and transverse joints in the drainage concrete are arranged congruently over the joint grid of the sub-concrete. The joint cut, if planned, is carried out in good time after the drainage concrete has hardened sufficiently.

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Structural engineering inspection

Sub-concrete

Concrete compressive strength (after 28 days): > 35 N/mm ²

Bending tensile strength (after 28 days): 5.5 N/mm ²

Surface tensile strength (after 28 days): 3.0 N/mm ²

Frost-de-icing salt resistance: high

Bonding bridge

Surface strength (after 28 days): 3.0 N/mm ²

Statistical ε-modulus (after 28 days): < 20,000 N/mm ²

Shrinkage: low

Frost-de-icing salt resistance: high

Drain concrete

Void content (after 28 days): > 15 vol-%

Concrete compressive strength (after 28 days): > 25 N/mm ²

Bending tensile strength (after 28 days): > 5.5 N/mm ²

Tensile strength (after 28 days): > 2.5 N/mm ²

Surface tensile strength (after 28 days): > 3.0 N/mm ²

Statistical ε-modulus (after 28 days): < 20,000 N/mm ²

Frost-de-icing salt resistance: high

Composite system
Surface tensile strength in the contact zone

(after 28 days): > 30 N/mm ²

Shear strength

(after 28 days): > 5.0 N/mm ²

Claims (6)

Hoechst Aktiengesellschaft Werk Kalle-Albert 94/K201G -14- 4.11.1994 WL-Dr. Fe-ef Protection claims 1. Drain concrete with 10 to 35 vol.% void volume, containing a hydraulic binder from the cement series and a polymeric binder in the form of an anionic styrene/acrylate copolymer whose minimum film formation temperature (MFT) is above 30 ^° C, as well as aggregates with grain sizes in the range of 2 to 10 mm. 2. Drain concrete according to claim 1, characterized in that the void volume is 20 to 25 vol.%. 3. Drain concrete according to claim 1, characterized in that the proportion of the polymeric binder is 10 to 20% by weight, based on the hydraulic binder. 4. Drain concrete according to claim 1, characterized in that the minimum film formation temperature (MFT) of the polymeric binder is 35 to 50 ^° C. 5. Drain concrete according to claim 1, characterized in that the proportion of the hydraulic binder is 15 to 25% by weight, based on the drain concrete. 6. Drain concrete according to claim 1, characterized in that the grain size of the aggregate is 5 to 8 mm.