DE4343482A1 - Concrete construction to contain water contaminating materials - Google Patents

Abstract

The first concrete layer (15) is formed as an unreinforced concrete slab with a min. quality of B 35, and a min. thickness (D) of 15 cm to 30 cm, dependent upon load. The second concrete layer (17) is formed as a concrete slab containing sealing additives, and of a thickness (d) of 8 cm to 15 cm, dependent upon load. Both concrete layers have a water-cement ratio W/Z of equal or less than 0,5 with an initial firmness betaD equal or greater than 20 N/mm2 after two days. Both layers may have reinforcements in their edge areas only. The layers are constructed without joints, if their size is up to approx. 30 m by 30 m.

Description

The invention relates to a concrete structure for the Dealing with water-endangering substances that result from a on a stable and frost-proof protective layer arranged first concrete layer with supporting function, a sliding layer thereon and one second concrete layer arranged thereon Sealing function exists.

For years, the production of liquid-impermeable concrete roadways for systems for handling environmentally hazardous substances, especially for Petrol stations and other filling and handling facilities, an abundance of interlinked problems. So far there was one laid in a sand bed Compound stone paving for the construction of roadways in the Gas station area common. Knowledge about Contamination in the subsurface Refueling areas due to drip loss and the fear of water protection, cited by Groundwater pollution has caused the to tighten the relevant regulations. Since are also looking for petrol station operators operational techniques for road construction. From the The result of regulations in particular results following requirements:

• a) in the first place there is a tightness and Impermeability of the road structure with the Guarantee required that contamination of the Soil and an associated risk to the Groundwater permanently excluded by fuel becomes. This requirement applies to both Area as well as all connections,
• b) constant visual control of the Tightness must be possible
• c) the usual traffic loads in road traffic must be able to be received safely; occurring Shear forces must not impermeability impair,
• d) after conversion and repair measures in The sealing must be done with little effort can be restored within a short time
• e) the runoff of rainwater and to ensure imported water and the height of existing components must be taken into account Slope situations between 2% and approx. 10% possible his,
• f) due to the tight schedule when building Petrol stations is a quick passability of the Lane required. The petroleum companies also call for the possibility of Sectional commissioning in order to continuous operation of a gas station to be able to maintain
• g) the conductivity and slip resistance must be off the TRbF (technical rules for flammable Liquids) and the occupational safety guidelines be respected. For rapid repairability to add that in the areas to be traveled  of the floor structure next to and on top of each other pipelines laid in a stable and frost-proof surface are, on the one hand, possible from external forces must be kept free and quickly accessible for repairs have to be.

In a known concrete structure of the beginning mentioned genre (see Darmstadt solid construction seminar, Volume 10, 1993, page 12, picture 15) is the first Concrete layer with a bearing function from one Reinforced concrete layer and the second concrete layer with Prestressed concrete sealing function. So far you were in the Experts predominantly believe that unreinforced Concrete layers only if they are safe To be able to use constructions. At the high Security requirements when dealing with water-polluting substances were believed to be on a Not being able to do without reinforcement. Some professionals specifically request concrete with reinforcement for both the upper as well as for the lower concrete layer. servant Reinforcement is the task, the emergence broader To prevent cracks and narrow them as possible keep to a penetration with water-endangering To reduce fabrics as much as possible. Such one Soil construction requires a lot more effort a longer construction time and arranges repair work extremely difficult and time consuming. There is one lower overall thickness of the floor structure always desirable because a tank, e.g. B. a fuel, Oil or the like. Tank, because of the gas bubbles when Suction pumps not at any depth below the Concrete layers can be laid and which in the load-bearing and frost-proof underground  Pipes with a gradient of 1% to 1.5% must be relocated.

In addition to the ones described above, there are also further suggestions as well as investigation reports on Dimensioning and dimensioning of concrete slabs in Petrol station areas, such. B. "DGMK Deutsche reports Scientific Society for Oil, Natural Gas and Coal e.V. research report 478 ". All of the Likewise, suggestions to be found cannot satisfy because the overall structure is too thick, the Concrete slabs take too long to build or in the event of damage require a time-consuming repair.

Based on this state of the art, the Invention, the object of a concrete structure to create the type mentioned at the bottom of the Overall thickness an extremely short construction time with early Resilience and easy to repair guaranteed and for which proof of tightness the relevant guidelines can be provided.

This task is in conjunction with the beginning mentioned generic term according to the invention solved that the first layer of concrete as unreinforced Concrete slab with a minimum grade of B 35 and depending on Load case with a thickness of 15 cm to 30 cm and the second concrete layer as sealing concrete additives included concrete slab and depending on the load a thickness of 8 cm to 15 cm is formed. Under these sealing concrete additives are not only Plastic dispersions, but also increased Parts of cement or additives in the form of microsilica  and / or pozzolans, such as fly ash or Electrostatic precipitator ash, or an increased amount of plasticizer Understood. This structure enables in use quickly hardening concrete formulations an extremely short Construction time, which, if necessary, after concreting the first unreinforced concrete layer the same day Overlay of the sliding layer the second concrete layer can be applied. By mixing Plastic dispersions in the second concrete layer due to the swellability of the plastics special sealing effect and thus a tight seal Upper class achieved. Furthermore, the Mixing water requirement as well as the tendency of the concrete to crack reduced, but not otherwise common in road construction Air entrainer is required. Furthermore, by the plastic dispersion the wear resistance against driving with heavy ones, for example Motor vehicles enlarged. The first layer of concrete with a minimum concrete quality of B 35 allows joints Avoidance of cracks, e.g. B. by Shrinkage processes, up to field sizes of approx. 30 m × 30 m can be dispensed with, joints only after other components or work sections required are. Furthermore, proof of tightness can now be provided for both layers of concrete according to the "guideline for concrete construction when handling water-polluting substances German Committee for Reinforced Concrete " (DAfStb guideline).

By arranging several sealing layers or the systemic interaction of the two Concrete layers as well as the sliding and separating layers contamination of the soil or groundwater  even if the second layer of concrete prevents it Lose sealing function due to cracking should.

Because the key sealing layer on the surface is also a permanent optical Controllability when cracks occur possible. Due to the multi-layer sealing layers in The new floor structure includes a sandwich construction great system security against the passage of water polluting substances, being its low Total thickness compared to other multilayer Solutions by using high strength and high density Single layers is guaranteed. In doing so all concrete-specific advantages, how long Service life, high resistance, conductivity, Slip resistance, abrasion resistance and relatively low Weather dependence, in full maintain. In the event of damage, the individual Layers of concrete easily with a diamond saw cut out and after performing the repair with plastic-modified repair concrete because of the missing reinforcement can easily be filled in again.

The two concrete layers advantageously have a water cement value W / Z of 0.5 with an initial strength β _D 20 N / mm² after two days. Furthermore, they are reinforced at most in their edge areas, whereas they are unreinforced in all other areas and can be designed seamlessly for field sizes up to approximately 30 m × 30 m. Joints are only necessary for connection to other components or work sections. In this case, the first concrete layer for shear force transmission is provided with joint anchoring or joint teeth at the edge areas.

To ensure tightness, the second contains Concrete layer with a plastic dispersion Plastic content of 14 kg / m³ of concrete and is on the Based on styrene butadiene or an acrylate manufactured. Another, inexpensive tightness can by admixing portions of microsilica and / or Fly ash can be achieved in both concrete layers.

According to an advantageous development of the invention, the sliding layer between the first and second concrete layers consists of a bitumen sheet with a thickness of at least 4 mm and a viscosity at 10 ° C. of η 10⁸ N · s · m ^-2 . This bitumen layer can not only transmit shear forces when braking for a short time, for example from braking of the vehicle as it drives upwards, but also has a sponge effect in the event of a minor leak in the event of a malfunction by literally "absorbing" the penetrating organic media or mineral oils.

However, it is also possible to use the sliding layer between the first and second layers of concrete polymeric films, e.g. B. from two superimposed PE films, with a minimum thickness of 0.2 mm per film to train. Likewise, between the first Layer of concrete and the stable as well as frost-proof Protective layer a separating layer from a single-layer PE film is provided with a minimum thickness of 0.1 mm.  

This exists below the two concrete layers load-bearing and frost-proof protective layer advantageous from a gravel or crushed stone base layer with a Thickness from 20 cm to 40 cm, in which in a sand bed Pipelines can be laid.

An embodiment of the invention is in the Drawings shown. Show:

Fig. 1 is a plan view of a gas station with tank places and arranged beneath the floor structure of the fuel tank,

Fig. 2 is a sectional view of the standard cross section along the line II-II of Fig. 1 and

Fig. 3 is a sectional view of a joint terminal along the line III-III of Fig. 1,.

FIG. 4 is a sectional view of the edge formation along the line IV-IV of FIG. 1.

Fig. 1 shows the plan view on a petrol station 1 having two tank centers 2, 3, and a filling station 4 with a total of five laid under the base region of the tank 5, which are connected by dashed lines indicated pipes 6 with the two tank courses 2, 3. The filling shafts of the tanks are labeled 7. The filling station 1 is connected or connected to the filling station 4 via the joint area 8 . Such joint areas 8 can also connect to the top and bottom 8 a, 8 b at the gas station, whereas the edge area is designated by 9 .

The concrete structure 10 according to the invention is shown in FIG. 2. A load-bearing and frost-proof protective layer 12 with a thickness D _o of 20 cm to 40 cm is arranged on a base 11 . This protective layer 12 consists of a gravel or crushed stone base layer, in which the pipes 6 are laid in a sand bed 13 . A separating layer 14 in the form of a single-layer polyethylene film is laid on the load-bearing and frost-proof protective layer 12 . The first concrete layer 15 is poured onto it as an unreinforced concrete slab with a minimum quality of B 35 and, depending on the load, with a thickness D of 15 cm to 30 cm. After the first concrete layer 15 has been walked on, a sliding layer 16 is placed thereon either in the form of a bitumen sheet with a thickness of at least 4 mm and a viscosity at 10 ° C. of η 10⁸N · s · m ^-2 or in the form of two PE films a minimum thickness of 0.2 mm per film applied.

Then the second concrete layer 17 is applied to the sliding layer 16 as sealing concrete additives containing concrete slab with a thickness d of 8 cm to 15 cm depending on the load.

When using "fast" concrete formulations in the first concrete layer 15 , it is possible with an extremely short construction time on the same day to apply the sliding layer 16 and the second concrete layer 17 , so that the entire concrete structure 10 for cars already after two days and for trucks is navigable for about five days.

In this concrete structure 10 , the second concrete layer 17 takes on the sealing function, the absorption of temperature stresses, the load distribution and the wear resistance. Due to the swellability of the plastic dispersions contained in the second concrete layer 17 , for example in the form of styrene-butadiene or acrylate, with a plastic content of 14 kg / m³ concrete, a particularly high level of tightness against the penetration of mineral oils and other environmentally hazardous substances is achieved. The use of microsilica and / or fly ash in this second concrete layer 17 not only reduces the proportion of cement, but also increases the tightness and, depending on the mixing ratio, increases the concrete compressive strength by at least β _W28 = 55 N / mm².

In addition, their use and the swellability of the plastics reduce the mixing water requirement, which results in a lower water / cement value. Furthermore, the tendency of the concrete to crack is reduced and, at the same time, the wear resistance is increased, while due to the lower mixing water requirement, water secretion in the concrete edge zones is reduced. The air entraining agent that is otherwise customary in road construction is not necessary in this concrete structure 10 .

As far as the sliding layer 16 consists of bitumen, it not only takes over the transmission of shear forces in the event of short-term stress, e.g. B. as a result of the braking forces of the ascending vehicles, but in the event of a malfunction sucks up small leakages of fuels and oils like an "integrating sponge".

In addition to its supporting function, the first concrete layer 15 with a minimum quality of B 35 also performs an additional sealing function. The proof of tightness "non-cracked concrete" is possible according to the DAfStb guideline.

In the case of field sizes up to approx. 30 m × 30 m, such a concrete structure either requires no or only slight joints 8 , reinforcement at best only having to be used in the edge regions 8 a, 8 b and 9 . This lower concrete layer 15 has an initial strength β _D 20 N / mm² after two days.

FIG. 3 shows the cross-sectional view of the joint 8 from FIG. 1. Parts corresponding to those in FIG. 2 are designated with the same reference numerals. In this area of the joint 8 , the first concrete layer 15 is provided on the right half of the picture with a groove 18 and in the left half of the picture with a tongue 19 that fits in with it, so that in this area of the first concrete layer 15 as well, a reliable transmission of vertical and shear forces is guaranteed. The sliding layer 16 is carried out continuously. In the second concrete layer 17 with the plastic dispersions or other sealing concrete additives, a joint insert 21 is introduced in a joint gap 20 , which is closed in the vicinity of the surface 17 a by mineral oil-resistant joint sealant 21 a. The pipes 6 as line connections between the tanks 5 and the gas stations 2 , 3 , which can also run along and parallel to a joint 8 , are not shown in FIG. 1, but are shown in FIG. 3. Due to the tongue and groove connection 18 , 19 in the first concrete layer 15 , this pipe 6 can also be laid in this area of a joint 8 .

Fig. 4 shows a sectional view of the formation of the edge 9 of Fig. 1 along the section line IV-IV. Parts corresponding to FIGS . 2 and 3 are designated by the same reference numerals. This edge 9 is closed by a composite stone pavement 22 , which is laid in a sand bed 23 . This is followed by a flush upward facing edge 15 a of the first concrete layer 15 . At this edge 15 a of the first concrete layer 15 , the sliding layer 16 is laid up to the inner edge 15 b. The second concrete layer 17 is laid thereon with a subsequent joint 8 , which corresponds in structure to the joint 8 from FIG. 3. This second concrete layer 17 has a drainage channel 17 b on its area facing the edge 15 a. This drainage channel 17 b is inclined according to FIG. 1 in the direction of the floor inlet 24 .

The essence of the invention resides in the combination of an unreinforced construction concrete which can be created within an extremely short construction time and which, in contrast to the prior art, now also performs a sealing function due to the high quality B 35 first concrete layer 15 in connection with the sliding layer 16 and the second concrete layer 17, also unreinforced, but interspersed with sealing plastic dispersions. This creates a concrete structure that meets all requirements for the sealing and wear function, which ensures a considerably smaller thickness D + d compared to the previously unreinforced concrete structures. This total thickness D + d can not be chosen arbitrarily, but must be as small as possible because the tanks 5 below the concrete structure 10 must not be lowered as desired. Because the pipes 6 are - starting from the tanks 7 in the direction of the gas stations 2 , 3 - laid with a gradient of 1% to 1.5%. Depending on their length between the tanks 5 and the filling stations 2 , 3 , the pipelines 6 then end at an unfavorable depth below the filling stations 2 , 3 . This applies in particular to large petrol stations or other handling areas of water-polluting substances. Since these water-polluting substances are pumped into the vehicles to be refueled by suction pumps at the end of the pipelines 6 at the level of the petrol stations 2 , 3 , excessive suction bubbles can result in considerable gas bubbles, which must be avoided under all circumstances. For this reason, the total thickness D + d must be kept as small as possible. The experts have provided the first and second concrete layers 15 , 17 with steel reinforcement because they assumed crack formation and wanted the reinforcement to have a crack-width-restricting function. A reduction in the overall thickness was not associated with this. As already described, these reinforced concrete slabs are not only associated with a relatively long construction time, but also with further considerable difficulties in the case of repairs. In contrast, the concrete structure 10 according to the invention can be cut out with a diamond saw in the event of a repair at the damaged point and then easily filled again with plastic-modified repair concrete.

Reference list

1 gas station
2 , 3 gas stations
4 filling station
5 tank
6 pipes
7 feed chutes
8 joint area
8 a top of the joint area 8
8 b underside of joint area 8
9 edge area
10 concrete structure
11 underground
12 protective layer
13 sand bed
14 separation layer
15 first layer of concrete
15 a edge of the concrete layer 15
15 b inner edge of the concrete layer 15
16 sliding layer
17 second layer of concrete
17 a surface of the concrete layer 17
17 b drainage channel
18 groove
19 spring
20 joint gap
21 joint inlay
21 a joint sealant
22 composite stone pavement
23 sand bed
24 floor drain
D thickness of the first concrete layer 15
d thickness of the second concrete layer 17
D _o thickness of the protective layer 12

Claims (14)

1. Concrete structure for handling water-polluting substances, which consists of a first concrete layer with a supporting function arranged on a stable and frost-proof protective layer, a sliding layer thereon and a second concrete layer arranged thereon with a sealing function, characterized in that the first concrete layer ( 15 ) as unreinforced concrete slab with a minimum quality of B 35 and depending on the load case min. a thickness (D) of 15 cm to 30 cm and the second concrete layer ( 17 ) as sealing concrete additives containing concrete slab and depending on the load case with a thickness (d) of 8 cm to 15 cm is formed. 2. Concrete structure according to claim 1, characterized in that both concrete layers ( 15 , 17 ) have a water cement value W / Z of 0.5 with an initial strength β _D 20 N / mm² after two days. 3. Concrete structure according to claim 1 or 2, characterized in that both concrete layers ( 15 , 17 ) are reinforced at most in their edge areas ( 8 a, 8 b, 9 ), but are unreinforced in all other areas. 4. Concrete structure according to one of claims 1 to 3, characterized in that the concrete layers ( 15 , 17 ) for field sizes up to about 30 m × 30 m are seamless. 5. Concrete structure according to one of claims 1 to 4, characterized in that the two concrete layers ( 15 , 17 ) are provided with joints ( 8 ) for connection to other components or working sections. 6. Concrete structure according to claim 5, characterized in that the first concrete layer ( 15 ) for transverse force transmission at the edge regions ( 8 a, 8 b) is provided with a joint dowel or joint teeth. 7. Concrete structure according to one of your claims 1 to 6, characterized in that the plastic dispersion in the second concrete layer ( 17 ) with a plastic content of 14 kg / m³ of concrete is included. 8. Concrete structure according to one of claims 1 to 7, characterized in that the Plastic dispersion based on styrene-butadiene or an acrylate.   9. Concrete structure according to one of claims 1 to 8, characterized in that both concrete layers ( 15 , 17 ) contain portions of microsilica and / or fly ash. 10. Concrete structure according to one of claims 1 to 9, characterized in that the sliding layer ( 16 ) between the first and second concrete layers ( 15 , 17 ) of a bitumen sheet with a thickness of at least 4 mm and a viscosity at 10 ° C of η 10⁸ N · s · m ^{-2 is} formed. 11. Concrete structure according to one of claims 1 to 9, characterized in that the sliding layer ( 16 ) between the first and second concrete layers ( 15 , 17 ) made of two polymeric films, for. B. consists of two superimposed PE films with a minimum thickness of 0.2 mm per film. 1 2. Concrete structure according to one of claims 1 to 11, characterized in that between the first concrete layer ( 15 ) and the load-bearing and frost-proof protective layer ( 12 ) a separating layer ( 14 ) made of a single-layer PE film with a minimum thickness of 0.1 mm is provided. 13. Concrete structure according to one of claims 1 to 12, characterized in that the load-bearing and frost-proof protective layer ( 12 ) consists of a gravel or crushed stone base layer, in which pipes ( 6 ) can be laid in a sand bed ( 13 ). 14. Concrete structure according to claim 13, characterized in that the gravel or the ballast base layer ( 12 ) has a thickness (D _o ) of 20 cm to 40 cm.