Liquid soil
Liquid soil is a flowable filler or a temporarily flowable filler material . Excavated soil material intended for backfilling is made flowable in order to use it for the installation of underground components . For this purpose, a mixture of excavated material and additives (plasticizer, accelerator, stabilizer), as well as added water and, if necessary, special lime is produced and filled. In special cases, other materials can be added to specifically change individual properties.
This manufacturing process makes it possible to make any types of excavated soil , industrially produced and natural aggregates , as well as other mineral substances temporarily flowable, to build them back in self-compacting and to restore soil-like to ground-level conditions in terms of soil mechanics and soil physics.
overview
As a frictional, cohesive, reconsolidating material, liquid soil belongs to the group of temporarily flowable, self-compacting backfill materials and can have consistencies from plastic to flowable , whereby the soil mechanical properties of liquid soil can be controlled. Liquid soil has no closed, rigid, constraining foreign structures, e.g. B. by hydraulic binders .
In reconsolidation, liquid soil has a high volume stability under installation conditions due to permanently stable water binding of the bulk of the added water and does not contain any environmentally harmful additives and therefore has no impermissible influence on the soil ( BBodSchG ) and the soil-groundwater pathway . In order to guarantee the high quality of liquid soil, the Quality Association for Liquid Soil, recognized by the German Institute for Quality Assurance and Labeling, was initiated by clients, network operators and municipalities and founded in 2009 to represent the interests of the quality requirements of network operators and road construction developers.
Components
Source material
Any types of excavated soil or other mineral substances are the starting material for the production of liquid soil . Liquid soil can not only be made from any excavated soil, but also from selected recycling material without residual hydraulic or unplanned ingredients that change the moisture balance and from other suitable bulk materials.
Additives
Specific plasticizers are used as additives in liquid soil, accelerators, specific stabilizers, which can be described as soil-like because they consist of materials that also occur naturally in the soil (e.g. clay minerals ), as well as added water and, if necessary, special lime. Additives of the type and amount that force the formation of macroscopic , rigid, interlinked, solid, the properties of the starting material and thus very low-deformation foreign structures in the soil are unsuitable.
Plasticizer
The additive that enables the temporary flowability of a backfill material from soil etc. is called a "plasticizer". A plasticizer has the task of keeping the added water in the flowable state of the liquid soil in the soil matrix (retention capacity). A plasticizer thus also enables the formation of a water film or sliding layers between the soil particles and thus the temporary flowability of the corresponding soil matrix . Plasticizers can be, for example, cellulose derivatives , bentonite suspensions , chemical flow agents and special layer minerals . Their suitability must be checked and proven in each individual case. Specifically modified layer minerals have proven themselves as plasticizers for liquid soil . Even in small amounts, these can absorb larger amounts of water from a soil in a stable manner and under installation conditions permanently.
accelerator
Hydraulic accelerators are currently mostly used as accelerators. Other materials are also suitable as accelerators, but at the moment they are usually considerably less favorable economically. Hydraulic accelerators are cements that have a suitable and specially required course of hydration . They remove added water from the added plasticizer in an accelerated manner at a defined time. As a result, the sliding layers are broken down and frictional force is created on the soil particles of the liquid soil matrix. As a result, the previously flowable material becomes plastic. Then the rest of the added water is permanently absorbed and bound by the “stabilizer” that is also fed into the process.
As a result of the plasticization, which can be controlled over time, the early load-bearing capacity of a “liquid floor” can be set and changed within certain limits if necessary. Cement accelerators may only be used in such a way that the so-called "cement point" is definitely not reached. As the cement point is exceeded, the cement stone structures begin to interlink increasingly. As a result, the soil matrix is increasingly interspersed with a rigid, non-soil lattice structure . As a result, the physical properties of these constrained structures of the now hydraulically bound material increasingly overlay the properties of the soil used.
stabilizer
An additive, which further reduces the plasticity of the liquid soil brought into the excavation by an accelerator and thereby promotes the reconsolidation with the original properties of the soil, is called a stabilizer. Cements and a. Hydraulic binders are unsuitable as stabilizers because they lead to the formation of the above. rigid foreign structures in the ground. An area filled with such a material behaves like a foreign body (e.g. under a road), which shapes the known damage patterns of damaged roads. Only liquid soil as a soil-like filling material makes it possible to avoid such damage.
Water and lime
The added water is the amount of water that is added to the liquid soil (depending on the required consistency) in order to make it flowable at times. Special lime is used for conditioning extremely clayey or moist and non-pourable soils. Its special properties prevent uncontrolled post-hardening ( pozzolanic reaction ), as can be observed again and again with conventional liming of such floors.
Liquid soil method
The liquid soil method enables excavated soil to first be brought into a plastic to flowable state by mixing it with additives and water and then reconsolidated with the soil-mechanically relevant properties of the starting material or with specifically modified properties. Liquid soil has special, time-dependent properties. The consistency during processing can be adjusted from flowable to plastic. "Reconsolidation" takes place on the basis of permanently stable water binding in the soil matrix or on the basis of the structures of the layer minerals added.
Because no non-soil additives and therefore no harmful chemicals are used, the use of liquid soil leads to an active protection of the soil (BBodSchG) and the soil-groundwater pathway (BBodSchV). The examination and evaluation of the initial soil , its evaluation, the use of the specially suitable additives and the correct implementation of the recipe by qualified specialists and suitable manufacturing technology ensure high-quality liquid soil production.
Distinguishing features
Liquid soil can be differentiated according to:
- the processing consistency (e.g. flowable, plastic),
- the type of production (stationary or mobile production)
- the place of manufacture (on site or manufactured externally),
- the specific properties of the end product and
- the raw material (excavated soil or other raw material).
quality control
Quality management
In order to ensure the high quality of liquid soil in the sense of avoiding foreign bodies under roads in backfilling areas, the RAL Gütegemeinschaft Liquidboden, recognized by the RAL German Institute for Quality Assurance and Labeling , was encouraged by clients, network operators and municipalities and as a representative of the quality requirements of network operators and road construction developers founded in 2009.
The minimum scope of the requirements to be complied with for the use of the liquid soil method , the necessary tests and the sensible processes are specified by the quality and test provisions of the RAL quality mark 507 (RAL Gütegemeinschaft Liquid Soil e.V.). In the summary of the experience gained with the process since 1998, the requirements of this quality mark represent the basis for quality assurance .
There are also other independent institutions that deal with the complex field of quality assurance in the area of liquid soil.
Federal Quality Association for Liquid Soil.
The aim is to promote liquid soils as an innovative building material and economical construction method by ensuring quality, information, training for manufacturers and processing companies and research. The quality assurance is based on the "Notes on temporarily free-flowing backfilling materials made of soils and building materials (ZFSV)" from the Research Association for Roads and Transport (FGSV), which represents the relevant set of rules for liquid soils. According to this quality guideline, quality-assured liquid soil bears the BQF quality mark.
Liquid soil with the QF quality mark guarantees consistently high quality through neutral quality assurance:
- the manufacturer's equipment and laboratory equipment is certified by neutral testing institutes
- The management staff must have successfully completed the BQF specialist courses.
- The soil parameters relevant to the FGSV information on liquid soils (ZFSV) are regularly monitored by neutral testing institutes as part of the BQF quality assurance of liquid soils.
monitoring
Liquid soil is not subject to any mandatory external monitoring by a recognized body. By commissioning voluntary external monitoring, the manufacturer documents the customer's trust in the quality assurance of liquid soils. External monitoring is carried out by neutral and independent bodies.
RAL Quality Association for Liquid Soil eV
The regulations governing the principles of quality assurance of liquid soil (e.g. ZTV-A-StB97 ) prescribe the types of monitoring: In the case of self- monitoring, the company carrying out the work monitors itself; in the case of external monitoring, a recognized monitoring body also monitors. In principle, self-monitoring must always be carried out. It includes the implementation of the necessary tests and their logging.
The special quality assurance of the liquid soil is carried out by:
- Scope of initial test in accordance with the guidelines of RAL GZ 507 (suitability test)
- Self-monitoring scope according to the guidelines of RAL GZ 507
- External monitoring scope according to the guidelines of RAL GZ 507
The quality and test regulations of the RAL Gütegemeinschaftiquidboden e. V. including the associated test requirements and rules stipulate all the requirements to be met for the use of liquid soil on the basis of the experience of developers and users. These provisions are currently available in their 2nd version in the form agreed in the quality association. The latest findings from research and application are continuously incorporated into these principles of quality assurance.
The Building Materials Monitoring Associations (BÜVs)
The BÜVs are accredited and regionally active monitoring and certification associations. The external monitoring and certification of liquid soils by the BÜVs includes the initial inspection of the member plants including checking and assessment of the suitability test as well as the regular monitoring of the in-house production control (WPK) on the basis of a BÜV-uniform monitoring and certification process. With regard to the product properties and the scope of testing within the framework of the WPK, the requirements according to H ZFSV apply. If the relevant requirements are met, the BÜVs award the association's product quality mark for liquid soil in accordance with their product mark statutes.
Qualification and further training
The acquisition of the qualifications to be a certified quality assurance officer for liquid soil according to RAL quality mark 507 takes place with the examination by the RAL Gütegemeinschaft Liquidboden e. V. in cooperation with research facilities at universities and institutes that are already experienced in this field and with process developers.
Technical specifications
The values to be achieved for the respective liquid soil on the concrete object are determined on the basis of the local soil conditions and the structural requirements of the respective construction site as part of the target value determination before the start of construction. These target values are adhered to in the form of the respective liquid soil formulation within specified tolerance limits, whereby the quality of the implementation is secured by the quality and test provisions in the 2nd version from 2010.
Exemplary values of a liquid floor tested according to RAL GZ 507 depending on the soil classification according to DIN 18196 (of the original floor ):
- Density : 1.6 - 2.4 kg / dm 3 (installation / final state largely identical) in the manner of the definition described here
- Compressive strength according to DIN EN 18136 and depending on the respective soil between z. B. 0.1 to 0.3 for Bk3 or up to 0.8 N / mm² for Bk5 (depending on the determination of the target value)
- Solvability according to DIN 18300 : soil class 3–5 (depending on the determination of the target value)
- E v 2 value according to DIN 18134 : after 28 d> 45 MN / m²
- Water permeability according to DIN 18310: 10 −5 to 10 −10 m / s (depending on the determination of the target value)
- Environmental and water harmlessness according to the verification required by the RAL quality mark 507.
Systematics
At times flowable, self-compacting backfill materials
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The distinction between the temporarily flowable backfill materials is usually based on:
- Type of reconsolidation process (e.g. frictional, cohesive, reconsolidating or hydraulically setting),
- Type of raw materials used (e.g. natural materials such as soil or artificially processed materials such as sand / gravel and recycled building materials ),
- Type of use and special end properties (e.g. soil-like behavior or material that is specifically provided with special properties),
- the dry bulk density ,
- the compressive strength .
The delimitation of the cohesive, frictional consolidation from the hydraulically setting materials is made on the basis of objective test and measurement results of the materials and through knowledge of the significant differences between these material groups. This knowledge is acquired in the basic area of civil engineering studies and in the training courses with subsequent certification by the RAL Gütegemeinschaft e. V. mediated by the teaching staff of German universities and institutes (see example opposite: measurable differences in the effects of pressure through fracture compression in uniaxial compression tests (according to DIN 18136 )).
Frictional, cohesive, reconsolidating materials (liquid soil)
As a frictional, cohesive, reconsolidating material, liquid soil belongs to the group of temporarily flowable self-compacting backfill materials.
Features and characteristics:
- Reconsolidating through the permanently stable installation of the mass of the added water in the material structures, with the consequence of the abolition of the sliding layers and the resulting formation of frictional forces and increased cohesion between the soil particles
- the absence of rigid, constraining structures leads to material properties that can change and adapt analogously to changes in external conditions (e.g. air humidity, load, temperature) in the soil
- Preservation of the soil mechanical properties of the original soil
- can be made from any excavated material (soil), as it does not necessarily depend on boundary conditions (e.g. non-human environment for the solidifying reaction of hydraulic binders)
- individual properties can be changed in a targeted manner
Examples:
- Liquid floor according to RAL GZ 507 e.g. B. RSS liquid soil or according to the quality guideline QRF z. B. WBM liquid soil
- Liquid soil on the basis of component-related functional separation z. B. separate material for plasticization and stabilization
- Liquid soil based on multifunctional components z. B. plasticizer and stabilizer in the form of one component
- Third-party productions using procedural rights (e.g. AggReFlow)
- Liquid soil RFB, made on the basis of natural aggregates using environmentally friendly, mineral additives and water
Hydraulically setting materials
Features and characteristics:
- represent mixtures of hydraulic binders with sand, RC building materials or soil
- reconsolidate through the formation of rigid, constraining structures that are foreign to the soil and thus overlay the properties of the starting material
- change the soil mechanical properties of the raw material significantly
- lead to material properties that cannot adapt to changes in external conditions (such as air humidity, load, temperature, etc.) in the soil
- thus lead to foreign bodies in the soil with properties that are not typical for the soil
- mainly not economically producible from any excavated material (especially not from strongly cohesive, clayey or humic soils)
- Production mostly through pure mixing processes
- The bulk of the added water must evaporate, diffuse and drain, which in the case of non-self-supporting grain structures leads to shrinkage and, as a result, to additional settlements
Materials made from industrially produced aggregates
Examples:
Materials shrinking in the reconsolidation phase (up to over 10%)
Examples:
- Foam concrete according to DIN 4264
Contain naturally existing soils as a supplement
Examples:
- Earth concrete
- Floor mortar
Building materials containing no aggregates, materials that shrink relatively little during the reconsolidation phase
Examples:
- Binders - suspensions , e.g. B. clinker , latent hydraulic substances and inert fillers , as well as additives to control the rheology and the settling behavior
history
To install underground components, the corresponding floor area must first be excavated as a soil and later largely or completely backfilled with soil. The upper or top floor filling area can also be used as a substructure for traffic routes. For the long-term usability of the components, it is advantageous if the originally excavated soil can be reused for backfilling.
For the economical installation of this excavated soil, the liquid soil method was developed by the privately-owned Research Institute for Liquid Soil GmbH (formerly LOGIC-Logistic Consult Ingenieurgesellschaft mbH) from 1998, patented in various variants and used as a term both for the first time and in the sense of restoring the original soil situation stamped after excavations .
The liquid soil method was developed in the course of numerous national and international research and development projects, which began with the development of a combination shaft system.
The conventional, at times flowable building materials such as dams, fillers, foam concrete , floor mortar etc., all hydraulically hardening materials, did not sufficiently meet the technical requirements for a suitable filling material and the optimal protection of the installed lines and pipes. Only a ground-like to ground-level behavior of the backfill material ensures the same load-bearing capacity in the subsoil and thus the freedom from settlement of roads, substructures with pipes and lines. For example, foreign bodies that damage the pipes are more in the road surface. The need for the successful development of the liquid soil method arose from technical constraints and environmental requirements (e.g. recycling and waste law ).
The development work since 1998 has led to technical and technological solutions that can ensure the later accessibility of all pipes lying one above the other, even without opening trenches and without relocating higher-lying pipes and pipes, a revolution in sewer and pipeline construction . The development of a method for using all types of soil relevant to building technology was also preceded by the desire to overcome known quality problems for canals, pipes and roads:
- Settlement as a result of compaction problems or as a result of drainage in the backfill areas
- Settlement as a result of backfill material that does not behave the same way as the surrounding soil in terms of shape and size
- Broken pipes as a result of poor compression of the gusset
- Road damage as a result of non-compacted shoring tracks
- Road damage as a result of the stamping of solid foreign bodies under the road or washouts and sags
- Road and pipe damage as a result of a lack of bond between backfill material and trench walls
- Consequences of the violation of environmental requirements of the legislature.
Research and development projects
Examples of the liquid soil process developed in the course of numerous national and international research and development projects :
- Research Institute for Liquid Floor GmbH: Experimental development of a liquid floor according to RAL GZ 507, taking into account project-specific and regulatory-specific requirements
- University of Regensburg : Soil mechanics basics and district heating applications from RSS liquid soil
- District heating research institute FFI Hannover: industrial research for district heating applications by RSS liquid soil
- University of Bochum and Institute for Underground Infrastructure (ICT) Gelsenkirchen: Testing of the liquid soil method
- RWTH Aachen University (Rheinisch Westfälische Technische Hochschule): Avoidance of pipe deformation and vibration damping by means of RSS liquid soil
- SP Sveriges Provings- och Forskningsinstitut Göteborg: Winter suitability of RSS liquid soil
- TU Dresden u. a. Partner: Use of the immobilization possibilities of the RSS liquid soil process for the recovery of contaminated waste
- Berliner Wasserbetriebe: Berlin large-scale tests on the material behavior of RSS liquid soil in comparison with hydraulic backfill materials, financed by Berliner Wasserbetriebe
- Stadtentwässerung Göttingen: pioneering work in quality assurance of liquid soil applications in sewer construction
- DEUS 21 with the Fraunhofer Institute Stuttgart: RSS Liquid soil and complex routes with innovative solutions for the design of infrastructure systems (new urban planning solutions)
- Dortmund; R&D project MUNIS: Use of complex routes using the example of a comparison of the complex RSS system with other route forms
Building theory
Structural principles
According to ZTV-A-StB 97, structural damage can only be avoided if the backfill material, when installed, exhibits the soil mechanical behavior that is typical for the surrounding soil. Otherwise the backfill material becomes a "foreign body" and reacts differently in terms of soil mechanics and building physics than the surroundings of the backfill area. This is one of the most important reasons for known structural damage. Working group 5.3.2 of the FGSV included this statement in the principles of the draft version of the data sheet TP BF-StB, Part B 11.3. For the first time, these principles are fully and completely met by liquid soil.
Requirements for damage-free construction
In order to ensure optimal paving quality and to avoid road damage, the backfill materials used in sewer construction must behave in a way that is typical of the soil. Care must also be taken to avoid an unfavorable pipe support angle, inadequate compression of the gusset or shrinkage of the backfill material. The protection of the built-in components (pipes, lines, cables) from mechanical damage and chemical effects must be guaranteed by the filling material used.
The backfill areas (pipe trenches) must be backfilled in order to avoid pipe and road damage in such a way that settlement can be excluded. The pipes must be exposed to dynamic loads, e.g. B. from traffic loads (damage to the bedding, damage to pipe connections and branches, etc.). Inadmissible post-hardening of the backfill material beyond the extent of the drying out of clayey soils must be avoided. The excavated material must be reused in an environmentally and ecologically correct manner. Any exchange material must be avoided in order to comply with the Recycling and Waste Management Act (KrW- / AbfG). The filling materials and their components must be completely harmless to the environment.
Construction practice
Advantages of liquid soil
Due to its flowability, liquid soil automatically fills the cavities when it is installed and thereby permanently ensures a stable material bond. This means that no economically complex mechanical compaction of the built-in soil is necessary. With liquid soil, narrow trench widths can be used and the excavated mass can be minimized.
In terms of town planning, traffic planning and construction, it is advantageous to install several underground lines or sewer pipes in narrow excavation areas next to one another and on top of one another and to fill them completely with the flowable material (liquid soil) that automatically fills all cavities. In contrast to other methods, the same material properties are present in all filled areas. Different densified areas are therefore not formed in the periphery of the pipe.
Even with the concentration of several or numerous underground pipe and / or sewer pipes in a few narrow installation areas, the cost of erecting, repairing and expanding complex urban and communal pipe and pipe systems (combined lines) is comparatively low when using liquid soil. With such complex routes, underground construction space can be kept free and later used advantageously for other traffic or infrastructural needs. Such construction measures are considerably cheaper, as no relocations are required and a route is created that can be flexibly adapted to changing conditions and user requirements.
The targeted urban planning use of this situation therefore enables the cost-effective and flexible construction and operation of settlements, as well as commercial and industrial areas with new advantageous solutions. Other usage concepts for inner-city areas can also be designed more easily and significantly more flexibly. This construction method was and is already used successfully. This also has an economically advantageous effect for the later operation of the networks if the laying areas in such combined lines can be arranged next to or due to the asymmetry of the combined shafts in the edge areas of the traffic routes. By using the original soil as backfill material in the form of liquid soil, the possible constructional disadvantages of other backfill materials (e.g. settlements or cracks in the road surface caused by foreign bodies created under the road) are avoided.
In addition, vibration damage to underground pipelines can occur through low-deformation underground foreign bodies, as well as deformations and cracks in the road surface through the use of a foreign material with increased or reduced swelling capacity when using such "foreign materials". This can be avoided by using liquid soil, as it noticeably and controllably absorbs vibration energy. The use of liquid soil also prevents the original excavated soil from having to be disposed of through complex transport processes and also to be replaced by foreign material in exchange. Those with the corresponding consequences for roads and the environment and the impairment of local residents are avoided. Apart from the economic advantage as a result of new technologies developed together with the liquid soil method, including the short installation time, liquid soil can make use of numerous construction-relevant advantages, such as: B .:
- the preservation of the soil-like properties of the original soil, which are advantageous for underground components, when it is used for the production of liquid soil;
- the achievement of an advantageous early loading capacity of the area filled with liquid soil as a result of the targeted change (control) of the refixation process within the limits of the method;
- an easily adjustable flowability or plasticity for the soil installation and thus the possibility of pumping liquid soil over long distances;
- the possibility of using any type of soil and thus also soils with biologically or mineralogically reactive components, d. H. humic soils;
- the property of the liquid soil, due to its easily adjustable flowability, also very narrow voids between underground pipe and pipe systems, as well as very tightly arranged excavation boundary surfaces, independent, complete and volume stable, d. H. to be filled in a settlement-free, positive and non-positive manner;
- the fulfillment of all requirements for an optimal backfill material for the permanent damage-free embedding of underground components;
- the possibility of making a floor in a variety of ways in all seasons (e.g. waterproof, water-permeable, frost-resistant or frost-resistant, heat-insulating or heat-conductive);
- the prevention of the discharge of pollutants in polluted soils;
- the applicability also for soils with mineral industrial or recycling components and for mineral recycling material with a soil-like grain distribution without influence on the refixing behavior;
- the complete fulfillment of all environmental requirements of the legislature, z. B. of the Recycling and Waste Management Act and thus the safe protection of the soil-groundwater pathway.
Recipe
Before liquid soil is used on the construction site, a standardized amount of liquid soil is produced in the laboratory that meets all the requirements. In doing so, soil conditions can also be taken into account that change significantly on the construction site if the recipe is created on the basis of the local preparatory work (soil assessment and sampling).
The production of the liquid soil takes place under defined conditions and from previously examined materials. The creation of the recipe and the determination of the target value are sensibly initiated by the client in the planning phase in order to prove the required material properties and to be able to use a sufficient lead time for sampling the excavated soil on site. The recipe is created after precise determination of the soil conditions in the construction site and the examination of the existing soil types on the basis of the soil mechanical target values to be achieved . For this purpose, representative samples are taken on the construction site, which serve as the starting material for the liquid soil recipe when creating the recipe.
The recipe is the instruction according to which liquid soil is produced. This is designed in such a way that it can be implemented on a large scale and also on site on construction sites. A liquid soil recipe is created in the laboratory by mixing the starting material with the additives, the added water and, if necessary, special lime. The results of this procedure are varied until they correspond to the specifications of the determined target values.
Manufacturing
Liquid soil is usually produced from the excavated material, but liquid soil can also be produced in the mixing plant using natural, recycled or industrially produced aggregates , provided these do not inadvertently influence the recipe specifications (e.g. residual hydraulic materials). The production must be carried out with suitable technology in such a way that it is possible at any time to check the correct adherence to and implementation of the values specified in the recipe. Therefore, the classic mixing technique is often not or only to a limited extent (e.g. for sand as a starting material) suitable. The production of liquid soil therefore usually requires special machine technology for soil, which corresponds to the special features of the process and makes the securing of frictional, cohesive reconsolidation manageable and controllable. Depending on which production technique proves to be most suitable for the structural conditions, in some cases a provision area of at least 400 to 800 m² with a sufficiently solid surface that is suitable for access by the technology used must be taken into account when producing the liquid soil in situ . If necessary, sufficient fastening including dismantling must be taken into account.
For the inner-city installation of liquid soil , however, mobile mixing systems are also very often available , which do not require more space than a conventional roll-off container but still have a very high productivity.
The requirements for the technology that is able to implement the liquid soil process without problems are set out in the quality and test regulations of the RAL Gütegemeinschaft Liquid Soil e. V. (2nd version 2010) or in the liquid soil quality guideline of the Federal Quality Association for Liquid Soil.
Compact system
A liquid soil compact system, equivalent technology or a combination of individual components must ensure the following functions for the in situ production of the liquid soil:
- Availability and dosing possibility of at least two dry components, optionally with cohesive soil of an additional third dry component, electronic quantity recording and storage of the added quantities as well as controllable output and readability of partial and total quantities as the basis for effective internal and external monitoring.
- Output of the quantities of liquid soil produced on a delivery note with corresponding minimum information (product description, recipe number, construction site, date,
- Manufacturer , construction company , amount of liquid soil, amount and type of dry components , slump, amount of added water, license plate number and name of the driver, time of completion of production, time of completion of installation)
- Suitable carrier technology with suitability of the technical solution for mechanical preparation and activation of the soil
- Suitable weighing device for weighing the quantities of soil supplied to the manufacturing process with data storage and output.
- Suitable process control that makes the process specifics for the production of liquid soil safely manageable and forgery-proof controllable and makes the entire process steps controllable according to the specifications of the recipes
- In the case of cohesive soils, the soil must be prepared with precisely metered special lime to produce free-flowing raw material and to record the amount of lime added
- Water connection with exact quantity measurement and dosage
- Power connection
- Suitable technology for filling the means of transport (e.g. concrete mixer, pumps)
- suitable means of transport for the transport and mixing process including the installation of the liquid soil at the intended location
- Suitable aids for the installation of liquid soil in order to avoid unnecessary spraying as well as an unfavorable load on the pipes or components to be installed by the liquid soil to be installed and thus avoid unnecessary problem situations
- Measuring and testing equipment for controlling, monitoring and documenting the process steps and results
The manufacturing process must be properly organized and technically secured. This must be coordinated with a third-party supervisor who is suitably qualified for the process and must also comply with the specifications of the liquid soil process and the system provider.
For the construction company that controls and uses the process, special personal qualifications are required for the planning, implementation and monitoring of the operation, such as:
- knowledge of the functional and technological material properties,
- the specifics of the process,
- the technology required for production, transport, installation,
- the necessary tests and measurements, as well as
- the test methods meaningful for the process and their applications and evaluations.
Installation
Shoring
The liquid soil method offers the possibility of a time-defined absorption of relatively high forces through the liquid soil that has just been installed. This force absorption can be controlled via the recipe. With targeted use of this possibility, the liquid soil can be used as part of the construction solution to improve technological processes, to simplify the construction effort, to secure the building structure and to avoid underground problems such as B. Risks of ground breakage etc. are used.
The sheeting must be selected in the planning phase in such a way that it enables a professionally qualified construction company to work with high quality and technologically correct working methods with liquid soil, in accordance with the conditions of the specific construction site. The necessary static verifications are part of the planning.
In built-in backfilling areas, the sheeting must be pulled while the liquid soil is still flowable or plastic in order to remove all cavities, e.g. B. to fill in the shoring track safely. The measurement of the re-fixation process necessary to determine the optimal time for pulling the shoring is possible using a measuring device (for example with the pipe-laying aid technology) and the measuring equipment that can be used for this purpose and should be recorded and stored to verify the correct implementation of the technological specifications according to the requirements of the quality assurance plan become.
If necessary, they are to be handed over as part of the quality assurance to the external supervisor contractually bound by the client for the application of the liquid soil method. The first of these measurements are made as part of the technical instruction and coaching by the system provider. The time to pull the shoring is derived from these measurements. The point in time for pulling the shoring is determined jointly by the system supervisor of the system provider with the person responsible on site from the construction company during the first measurements.
The system supervisor trains those responsible for the construction company within the framework of the coaching that is sensibly advertised.
The correct implementation of the technological specifications of the planning is based on the recipes determined in the planning phase and the properties of the liquid soil associated with these recipes (e.g. time-dependent load capacity, density, rheology). It ensures that the loads on built-in components are minimized. With flexible materials, minimal pipe deformations are ensured for pipes and, with rigid pipes, their freedom from disadvantageous pre-stresses when handled correctly. This is the prerequisite for optimal protection of the pipes against unwanted stress peaks and deformations and thus ensures a maximum failure-free service life. The timely correct pulling of the shoring is an important part of the minimization of loads on the components to be installed in the liquid soil and their subsequent position and functional assurance and should be checked and documented as part of quality assurance by the external supervisor on behalf of the client.
In the case of shoring types that use stiffening components to absorb the shear forces acting via the shoring (e.g. spindles, slides), these components must not buckle e.g. B. be burdened by aids to secure the position. The technology and technique of securing the position of components that are installed in liquid soil must be selected in such a way that this load does not arise in the said components (see adjacent figure: securing the position of pipes using a pipe-laying aid).
Securing the position of pipes and lines
A pipe laying aid is a mechanical device for securing buoyancy for pipe laying, complex pipe laying and large pipe laying with liquid soil.
It enables:
- easy and quick fixation, e.g. B. when laying large pipes and pipes in a separation system with several levels,
- the shortening of the construction time with less technology and fewer personnel,
- increasing labor productivity and saving construction costs,
- the exclusion of sources of error, such as shifting position or floating, i.e. no reworking and no unnecessary costs,
- avoiding permanent load concentrations (point loads) through conventional installation technology (e.g. through retaining benches and crossbars),
- installation above or between the sheeting or trench wall or asphalt edge,
- the elimination of weights on the pipes, which can push them into the ground and lead to unwanted and permanent stresses in the pipes,
- a stepless adjustment to the trench width and laying depth and
- easy assembly and disassembly thanks to plug connections.
This technique was also developed, tested and made ready for practice by the developers of the liquid soil method.
transport
As a rule, the liquid soil must be transported from the place of manufacture to the nearby or further installation location. So the material is z. B. with the truck mixer, with the appropriate consistency (kp or kf), to be transported to the installation site and properly introduced using suitable technology to protect against splashing, segregation or change of position of the pipes. These tools are available from the liquid floor system provider.
The liquid soil can also be installed with pump technology in suitable installation situations. The process developer has already overcome distances of over 600 m using pumps.
The bidder must secure the protection of the building against contamination etc. at his own expense.
For the production of the liquid soil from the excavated soil and for the operation of the system technology, the waste and immission law requirements must be met by an expert qualified and certified for the liquid soil process for soil protection and contaminated site treatment, approved according to § 18 BBodSchG , in cooperation with the external supervisor and to the competent authorities before the start of construction. The technology used by the construction company must also meet the immission requirements of the legislator. This is checked by the aforementioned specialists before the start of the liquid soil production and recorded in a written statement. If necessary, the competent authority must be consulted for this test.
The production of liquid soil on the basis of the technology to be used must be based on the weighing of all components with the required accuracy and an exact verification that is secured against incorrect operation and technical failures and easy to understand for external monitoring.
The requirements for such technology in the quality and test regulations of the RAL Gütegemeinschaftiquidboden e. V. (2nd version 2010) and should have been checked and verified before construction begins. These should also be the subject of the tender.
Areas of application
The application of the liquid soil method serves to embed underground components (e.g. pipe and sewer systems for rainwater , waste water and other media).
In sewer and supply line construction , liquid soil is used to fill trenches . Even if special properties of the backfill material are required, the liquid soil process is used to produce liquid soil. These properties include a. Settlement freedom, volume stability, quick build-up, the simple production and adaptability to the required structural properties. In the course of environmental protection, the excavated material should be reused as completely as possible in the canal construction on site.
The usability of all soil types, the ability to immobilize pollutants in certain contaminated soils and the reduction of trench widths when using liquid soil meet these requirements.
Areas of application are, for example, the filling and backfilling of structures, cavities, cellars, work rooms, the combined installation of supply and disposal lines in a combined trench, the construction of district heating lines, tunnel construction, power plant construction, road construction, hydraulic engineering ( dykes , dams , Molen , ponds , leaks , etc.), the area of thermal insulation, as well as the controlled heat dissipation (e.g. with electrical cables), the building protection (e.g. through vibration damping , thermal insulation , watertight liquid floor, etc.).
The liquid soil method is used for subsurface waterproofing, construction on slopes with great gradients , for slope and embankment stabilization , the construction of noise barriers , subsurface stabilization, protection against root penetration, floor slabs (e.g. for improved statics), in the area of monument protection, the targeted Surface protection of components against aggressive water, in the case of annular space filling, the sealing of leaky sleeves and the solution of exfiltration problems.
Applications for liquid soil also result from its special technological properties such as B. the controllable refixing, which is z. B. also makes it possible to quickly absorb shear forces from the development and thus to use simple and easily manageable types of construction.
Other possible uses are in the coloring, for example. B. for supply lines, in environmentally relevant applications (e.g. for building in drinking water protection areas ) and when installing large pipes.
In addition, there are additional application options for the structural use of conventionally unsustainable substrates, for building in groundwater or underwater z. B. for sewer construction, for construction under winter conditions, for the construction of head construction sites to accelerate the construction process.
An additional application example is pumping the material over long distances.
Many new applications are currently still under development and long-term testing by the system developer and his R&D partners. B. from the field of specialist planning for liquid soil applications and prepared for practical use.
Specialist planning
For the effective and safe use of the advantages of liquid floor construction, the fulfillment of the environmental requirements and the use of the financial, qualitative and temporal advantages, the specialist knowledge of specialist planners who have mastered the process and its specifics and who have acquired appropriate qualifications is required.
A specialist planner for liquid soil construction provides all the services necessary for the fulfillment of the structural and qualitative tasks of liquid soil use, which are currently not part of the scope of qualification for the training of urban water management specialists and civil engineers.
A specialist planner
- prepares the preparatory work for the tender , which enables the bidder to qualitatively identify the technological, logistical and technical features of liquid soil construction and to take them into account quantitatively in the calculation,
- supports and accompanies the main planners with the tender,
- represents the liquid soil-specific characteristics towards the bidder when awarding the contract,
- is liable for the correctness of the service descriptions and their feasibility,
- accompanies the execution and supports the technologies that are still relatively new for many construction companies,
- is responsible for the quality assurance of the use of liquid soil on the construction site specified in the tender,
- documents the construction work and evaluates it with the client and all those involved and indicates reserves in the overall process.
What should the client be aware of?
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In the context of the building specification and tender , not only the term “conventional material” may be exchanged for the term “liquid soil”.
An exact technological, technical and logistical description must also be provided so that the construction companies can include the economic advantages of using the technologies associated with the liquid soil method in their calculations.
Quality assurance already begins in the planning phase with the development of specific specifications for the production, installation, execution and properties of liquid soil. These special features must be adapted to the respective construction site .
The planning phase should be in the hands of a trained specialist planner who is also liable for the results of this work, has acquired the necessary specialist knowledge and can show it as proof of qualification.
Quality assurance should take place in the direct contractual relationship with the builder in the planning area in order to only be obliged to this. The services of qualified specialist planners are available for this purpose, who work within the scope of the work of the RAL Gütegemeinschaftiquidboden e. V. and experienced research institutions and universities can acquire these qualifications and have the necessary practical experience.
External and in-house monitoring is only carried out by the specialist planner after obtaining a valid qualification certificate.
Such specialist planning also includes continuous quality control during the formulation, manufacture, installation and securing of the desired final properties of liquid soil and comprehensive documentation of the overall process.
Requirements for an agreement between the client and the construction company
In an agreement between the client and the construction company , which includes the planning , the tender and the construction contract , exact requirements belong
- the properties of the filling material or liquid soil and the construction task to be carried out with it ,
- the execution in terms of technology , technology and logistics ,
- the fulfillment of the environmental and emissions requirements of the legislature,
- the quality standards to be applied and requirements for liquid soil, its production and installation (e.g. requirements according to RAL GZ 507)
- the type and scope of the tests and the evidence to be provided,
- the schedule of services in the context of quality assurance,
- the definition of self-monitoring by the construction company and
- the responsibilities of quality assurance and the competencies of the external supervision working on behalf of the client.
literature
Article in German
- O. Stolzenburg: What is liquid soil really? - Curse or blessing of a new process. bi UmweltBau 1/2009
- O. Stolzenburg: The advantages of using liquid soil for the pipe-soil system. In: T. Wegener (Ed.): 2004 - Pipelines in the year of technology. (= Series of publications from the Institute for Pipeline Construction Oldenburg. Volume 28). Vulkan-Verlag, Essen.
- O. Stolzenburg: Expert planning for liquid soil for correct technical implementation. Oldenburger Rohrleitungsforum, gwf-Wasser / Abwasser, 01/2010
- A. Zeller: The different suitability of cohesive and non-cohesive soils for filling pipe trenches. TWS Stuttgart AG
- A. Zeller: Different behavior of cohesive and non-cohesive soils. TWS Stuttgart AG
- A. Zeller: Winter damage to former pipeline and sewer construction sites - suggestions for their prevention. TWS Stuttgart AG
- G. Kühn: Liquid is conclusive - liquid soil production on site. In: bbr. (Specialist magazine for well and pipe construction) 04/2004.
- R. Schwartz: Combined sewer shafts in the public and private sector - an overview of the requirement profile. In: Wastewater Report NRW. 1/2003.
- R. Schwartz: Requirements for combined sewer manholes - what do regulations and operators require? bi UmweltBau 1/2002.
- P. Aldick: Sewer construction site with liquid soil completed quickly. In: Allgemeine Bauzeitung. November 9, 2007.
- H. Kinkopf: Save time and money without gravel. In: Heilbronn voice.
- HP. Pfeiffer: Use of liquid soil (practical report). In: Abwasser Report NRW. 2/04
- J. Delphendahl: Excavated soil flows back full pipe (technology for sewer construction). In: Rheinhessische Post. 3/04
- L. Jungmann: Secret recipe for a safe bed (new procedure). In: Westdeutsche Zeitung. 3/04.
- Documentation of the "Werra-Meißner Innovation Award" 05: When soils become liquid , (1st winner - WFG)
- H. Schröder, STEINZEUG Abwassersysteme GmbH: Embedded in liquid soil (ESO Offenbach is testing alternative methods). In: Steinzeug-Report. 1/06.
- C. Mayer: Liquid soil in Püttlingen - made by dittgen. In: Employee newspaper “durchblick” 7/06.
- G. Schulz: Liquid soil using every trick in the book. In: quarry and sand pit. 10/2008.
- M. Webeling, Olaf Stolzenburg: Possible uses of liquid soil in earthworks and civil engineering works In: Street + Autobahn. ISSN 0039-2162 Vol. 58, No. 10, 2007, pp. 556-561.
- J. Buchta: Liquid soil replaces sand. Article by Südwest Presse Online-Dienst GmbH from December 6, 2007, www.suedwest-aktiv.de,
Article in English
- J. Dziopak, NI Alexejev, O. Stolzenburg: Waste water accumulation in storage reservoirs within sewage systems. Conference "Science and innovations in modern construction - 2007", St. Petersburg, 2007.
Article in French
- Robert Curtat: Sols fluides or l'œuf de Colomb. In: Commune Suisse. 06/2005
- Fanny Noghero: Un sol fluide en première suisse. In: Courrier Neuchâtelois. November 9, 2005.
Article in Swedish
- S. Nilsson: Utvärdering av bärighet hos vägkropp med fjärrvärmeledning kryngfilld med RSS liquid soil. SP Sveriges Provnings- och Forskningsinstitut, 2005.
Article in Polish
- Jacek Nalaskowski, Biuro Ka-Nal: Technologia czasowego up? Ynniania gruntu w robotach kanalizacyjnych - na przyk? Adzie budowy kolektora "Bobrek" w Sosnowcu. In: Ochrona S'rodowiska. 1/2008.
- Ziemowit Suligowski, Politechnika Gdan'ska: Nowoczesna technologia instalowania rur z tworzyw sztucznych (metoda czasowego up? Ynnienia pod? Oz.a gruntowego). In: Wiadomos'ci. 12/2007.
- Ziemowit Suligowski, Politechnika Gdan'ska: Czy to jest w sieciach infrastructure? In: Inz'yniera Morska i geotechnika. 6/2007.
Norms, leaflets, standards and legal provisions
- ZTV-A-StB 97 indirectly defines the requirements for the backfill areas as restoring the initial situation (technical equivalence compared to the original state) and thus indirectly the requirements for backfill materials: These can only restore the undisturbed conditions if they have the same floor-level properties of the surrounding soil in the installed state have
- ZTV-A-TP BF-StB, Part B 11.3 Suitability tests for soil improvements
- RAL Gütezeichen 507 regulates the requirements for liquid soil in terms of restoring the initial state of the soil conditions, dd the typical soil behavior of the liquid soil in the backfill area, quality and test regulations of the RAL Gütegemeinschaft Liquid Soil e. V.
- Worksheet ATV-DVWK-A 127 Static calculation of sewers and pipes (08.2000) - only applies to the statics of the pipes in the installed state - does not yet record the installation state in the liquid soil - therefore a separate calculation for the installation state is necessary
- Worksheet ATV-DVWK-A 139 Installation and testing of waste water pipes and sewers (01.2002) (Ed .: German Association for Water Management, Waste Water and Waste - ATV-DVWK, Hennef) does not yet record the differences between flowable backfill materials and the the following aspects for construction and quality assurance from the new technological possibilities
- DIN 1054 subsoil - permissible load on the subsoil
- DIN 18300 VOB contract regulations for construction works - Part C: General technical contract conditions for construction works (ATV); Earthworks (12.2000)
- DIN 18310 Securing work on bodies of water, dykes and coastal dunes
- DIN 18134 Test to determine the compressive strength of soils and materials
- DIN EN 12350-5 Testing of fresh concrete - Part 5: Slump (08.2009)
- DIN 4124 construction pits and trenches - embankments, shoring, working space widths (10.2002)
- DIN EN 1610 regulates the basic requirements for sewer construction and also includes the liquid soil via flowable filling materials (10.1997)
- DIN EN 1610 Supplement 1 Laying and testing sewage pipes and sewers - List of relevant standards and guidelines (as of February 1997)
- DIN 18196 soil classification for structural purposes
- DIN EN 18136 subsoil - Investigation of soil samples - Uniaxial compression test
- DIN EN 933-1 Test method for geometrical properties of aggregates - Part 1: Determination of the particle size distribution - Sieving method , 1/2006
- DIN EN 1744-1 Test method for chemical properties of aggregates - Part 1: Chemical analysis , 2009.
- FGSV leaflet of the working group 5.3.2 Structural principles (ZTV-A), with reference to the restoration of the initial state of an excavation through the backfilling material and the backfilling process , (draft version March 2010)
- BBodSchG Federal Soil Protection Act, Act to protect against harmful soil changes and to remediate contaminated sites
- BBodSchV Federal Soil Protection and Contaminated Sites Ordinance ,
- KrW- / AbfG Recycling and Waste Management Act of September 27, 1994, Paragraph 5 - Basic obligations of recycling management
- LAGA (Land Working Group on Waste): Requirements for the recycling of mineral waste, technical rules of December 20, 2000. p. 4306.
- TASi (Technical Instructions for Municipal Waste ): Third general administrative regulation for the Waste Act of May 14, 1993 , (BAnz. Of May 29, 1993, p. 4967, with enclosures)
Web links
- Liquid floor with RAL quality mark
- Liquid soil - a versatile building material (August 11, 2009)
- - Vorarlberg premiere: excavated floors can be reused (March 5, 2010)
- Pour back the excavated material instead of throwing it away (April 9, 2010)
Individual evidence
- ↑ a b c d e f g h i j k Source: System provider -PROV- Produktions- und Vertriebsgesellschaft mbH -
- ↑ see DWA worksheet A 139
- ↑ Reference to the relevant information sheet. In: FGSV.de
- ↑ O. Stolzenburg: The advantages of using liquid soil for the pipe-soil system. In: T. Wegener (Ed.): 2004 - Pipelines in the year of technology. (= Series of publications from the Institute for Pipeline Construction Oldenburg. Volume 28). Vulkan Publishing House. eat
- ↑ Internet presence of the building materials monitoring associations, In: Buev-Baustoffueberendung.de
- ↑ H ZFSV - Instructions for the production and use of temporarily flowable, self-compacting backfill materials in earthworks [FGSV no. 563], www.fgsv.de
- ↑ Thomas Neidhart: Fundamentals of soil mechanics. University of Regensburg
- ↑ R. Frey, D. Funk, K. Stein: Erdboden-Zement-Stein: Macrostructure and basic properties. In: arcus. 5, 1984, p. 257.
- ↑ R. Frey, D. Funk, A. Kreidler: Investigations of the cement stone cage effect with cement-stabilized solid clay. In: arcus. 1, 1984, p. 43.
- ^ O. Stolzenburg: Possibilities for the holistic rehabilitation of pipeline networks in a European context. Oldenburg Pipeline Forum 2005.
- ^ O. Stolzenburg: RSS System - The underground logistics concept, multimedia solutions. bi-environmental construction 2001.
- ^ O. Stolzenburg: RSS Liquid soil in sewer construction - a practical report. Oldenburg Pipeline Forum 2004.
- ↑ O. Stolzenburg: Potentials of cost reduction and possibilities of location advantages with holistic renovation, renewal and new construction of pipeline networks in the age of liberalization of the market of the supply and disposal companies in Europe growing together.
- ↑ a b c d e f g h i Source: specialist planning LOGIC Logistic Engineering GmbH
- ^ Research Institute for Liquid Soil GmbH
- ↑ DEUS 21
- ↑ M. Webeling: TP BF-StB, Part B 11.3, aptitude tests for soil improvement.
- ↑ A. Zeller: The different suitability of cohesive and non-cohesive soils for backfilling pipe trenches. TWS Stuttgart AG