Geotextile

Geotextiles are versatile auxiliary materials for construction and deconstruction: they separate, filter, drain, protect, and reinforce. In work areas such as concrete demolition and special demolition, strip-out and cutting, rock excavation and tunnel construction, as well as natural stone extraction, they support safe and clean operations. In combination with hydraulic tools from Darda GmbH—such as concrete pulverizers or rock and concrete splitters—geotextiles assume important tasks, for example as protective layers, separation layers, or filter fabrics.

Definition: What is meant by geotextile

Geotextiles are textile construction materials made from synthetic fibers (mostly polypropylene or polyester) manufactured as woven, nonwoven, or composite products. Their key functions are separation of materials with different grain sizes, filtration of water while retaining fines, drainage within or along layers, protection of sensitive waterproofing, and reinforcement of soil. Selection is based on mechanical properties (e.g., tensile strength, static puncture resistance CBR), hydraulic properties (permeability, characteristic opening size), and durability aspects (chemical and UV resistance). Geotextiles are geosynthetics and are used in earthworks, civil engineering, hydraulic engineering, and deconstruction.

Tasks and operating principles of geotextiles

Geotextiles act by controlling material flows and protecting components. In deconstruction and demolition contexts they combine technical functions with practical occupational safety and cleanliness effects.

• Separation layer: Prevents mixing of granular base layers with fine-grained soil. For temporary site roads for hydraulic power packs and work tools, a separation layer prevents equipment from sinking and keeps the aggregate bearing.
• Filter action: Allows water to pass while retaining fines. During wet cutting or when flushing boreholes, a filter fabric limits the spread of slurries into drainage ditches.
• Drainage: Conducts water in a defined direction. Behind shotcrete in tunnel construction, a drainage nonwoven can direct water runoff to the collection line.
• Protective layer: Cushions mechanical impacts and protects waterproofing or membranes from damage caused by edges, sharp grains, or steel parts. When using concrete pulverizers and rock and concrete splitters, a protective layer reduces the risk of local damage to underlying waterproofing.
• Reinforcement: Woven geotextiles can improve load distribution, e.g., beneath gravel pads for work platforms.
• Erosion control: Stabilizes slopes and stockpiles, reducing the loss of fines due to rain or splash water.

Materials, product types, and key properties

Geotextiles are predominantly made from polypropylene (PP) and polyester (PET). PP is lightweight and chemically resistant; PET is characterized by low creep and temperature stability. Fibers are processed into woven fabrics (ordered structure, high tensile strengths with low elongation), nonwovens (needle-punched, isotropic and adaptable), or composites.

Woven, nonwoven, composite—what fits what?

Woven fabrics are suitable when high tensile strengths and low elongation are desired, for example for load distribution and reinforcement tasks under temporary traffic routes. Needle-punched nonwovens focus on protection, separation, and filtration functions and adapt to uneven subgrades—useful as protective layers over potentially sharp-edged residual concrete. Composites (e.g., nonwoven plus drainage core) combine filtration with directed conveyance.

Important parameters in day-to-day site work

• Tensile strength and elongation: Relevant for reinforcement and installation robustness.
• Static puncture resistance (CBR): A measure of resistance to localized loading—important where edges of demolition faces or reinforcement are present.
• Permeability normal to the plane: Controls drainage; helpful in deconstruction works to capture flushing and sawing water.
• Characteristic opening size (O90/AOS): Determines which grain fractions are retained—crucial for filter stability.
• Durability: UV stabilization, chemical resistance, temperature resistance—relevant for outdoor storage, cement slurries, or contact with alkaline water.

Geotextile in concrete demolition, special demolition, and strip-out

In the deconstruction of concrete components, varying grain sizes, water, and mechanical loads interact. Geotextiles structure these processes: As a cover fabric they reduce the fly-off of small chips when using concrete pulverizers and protect adjacent surfaces. As a protective layer beneath load distribution plates or steel mesh, they prevent damage to waterproofing in underlying layers. As a separation layer between fine soil and gravel, they improve the bearing capacity of temporary working areas for hydraulic power packs, combination shears, or Multi Cutters. Used in drainage channels, they act as a filter, allowing cooling and sawing water to pass while retaining fines.

• Covering and protection: Nonwoven rolls over sensitive components reduce contact and abrasion marks from concrete debris.
• Separation and cleanliness: Under provisional fills, geotextiles keep the gravel clean and load-bearing—important with changing approaches by rock and concrete splitters.
• Filtration and collection: In collection sumps or boxes, a filter nonwoven can retain fines from cooling and sawing water; maintenance remains predictable.
• Protection under equipment supports: Beneath steel plates and crawler undercarriages, a robust nonwoven reduces local punching in soft subgrades.

Geotextile in rock excavation and tunnel construction

In rock and underground works, particularly in rock demolition and tunnel construction, water management, material separation, and membrane protection are paramount. Behind shotcrete shells, protective nonwovens protect the waterproofing from sharp grains in the substrate. Drainage nonwovens can collect seepage water over an area and convey it to the drainage system. During drilling and splitting operations with stone splitting cylinders or rock and concrete splitters, geotextiles serve as separation layers beneath fills to prevent fines from migrating into bearing layers. On stockpiles and intermediate storage areas they stabilize the surface and reduce erosion.

Geotextile in natural stone extraction

In quarries, geotextiles serve as separation and protective layers to keep storage areas clean and traffic surfaces bearing. Under wooden or rubber pads, nonwovens protect sensitive stone surfaces during placement or gripping. In drainage sumps, filter nonwovens inhibit clogging. Geotextile containers and multi-layer nonwoven packs support dewatering of sawing slurries, enabling solids to be collected while water is discharged.

Selection criteria for geotextiles in deconstruction and separation works

The choice of a suitable geotextile depends on the construction task, grain-size spectrum, water management, and mechanical loading. The decisive factors are project requirements and recognized technical rules; these should be checked and documented for the specific project.

1. Define the function: Separation, filtration, drainage, protection, or reinforcement—possibly combined.
2. Assess grain-size distribution and water regime: Fine content, expected flow rates, standing water.
3. Consider mechanics: Point loads from debris, edges, reinforcement—required puncture resistance.
4. Check durability: Installation duration, UV exposure, temperature, chemical influences from concrete residues.
5. Installation and overlap: Handling on site, secure fixation, clean seams/overlaps according to the plan.

Compatibility with hydraulic tools

When using concrete pulverizers, rock and concrete splitters, combination shears, Multi Cutters, steel shears, or tank cutters, dynamic loads and edges act on underlying layers. A sufficiently puncture-resistant nonwoven (robust protective nonwoven or woven variant) reduces the risk of cuts and abrasion. Geotextiles are smooth; they must not enter moving parts. Fixation and edge guidance should therefore be planned so that the strips lie outside the working area.

Installation, storage, and quality assurance

Careful installation is crucial for functional reliability. Subgrades are cleared of sharp points and coarse irregularities. Rolls are laid with minimal tension and with overlaps; wrinkling is avoided. For filter layers, the laying direction follows the water flow; transitions remain continuous. Temporary fixation can be achieved by ballast (e.g., gravel) or suitable fasteners. Rolls are stored dry, UV-protected, and on level ground. Documented incoming goods inspection (key properties, delivery note, batches) and random visual checks and functional tests on site support quality assurance.

• Overlaps: Choose so that no openings occur even under jobsite movements.
• Cleanliness: Keep filter areas free of cement laitance and coatings of fines to maintain permeability.
• Protection during follow-on work: Do not traffic or drive over the geotextile unprotected if this would impair its function.

Sustainability aspects and circular economy

Geotextiles can organize material flows and thus conserve resources: clean bearing layers are easier to reuse after deployment, fines are retained in filters, and water can be routed and, where applicable, pre-clarified. Temporary protective or separation layers can—if uncontaminated—be reused. If reuse is not possible, proper separation and disposal must be observed. Statements on recyclability and service life depend on the specific product and its loading and should be evaluated on a project basis.

Typical mistakes and how to avoid them

Errors often arise from unsuitable selection or careless installation. A few basic rules help avoid functional impairments and consequential damage.

• Unsuitable opening size: Pores that are too large lead to material migration and settlements; pores that are too small promote clogging. Consider the grain-size distribution and water flow.
• Insufficient puncture resistance: Point loads from debris, steel edges, or crawler undercarriages require robust protective layers.
• Lack of fixation: Shifted strips lose their filter and separation function.
• UV damage: Prolonged exposure without protection reduces strength. Coordinate storage and construction sequencing.
• Clogged filter surfaces: Clean or replace regularly when filter nonwovens are used temporarily as dirt catchers.

Interfaces with products from Darda GmbH

Geotextiles complement hydraulic tools functionally without replacing their use. Practical examples illustrate the interfaces:

• Concrete pulverizers: Cover nonwovens to limit chipping, protective layers on waterproofing of adjacent components, separation layers under fill pads for stable access routes.
• Rock and concrete splitters: Separation nonwovens under gravel pads to prevent sinking; filter nonwovens to capture flushing water during drilling.
• Hydraulic power packs: Load-bearing work platforms with geotextile separation layers ensure mobility on variable subgrades.
• Combination shears and Multi Cutters: Protective nonwovens prevent damage to sensitive surfaces in the immediate vicinity of the cutting zone.
• Steel shears and tank cutters: Separation and protective layers for clean work areas; filter layers in collection sumps assist in discharging cooling and flushing water.
• Stone splitting cylinders: Geotextile separation layers stabilize drilling sites and material storage areas; erosion control protects stockpiles and traffic lanes.