A geotextile beneath a road is selected to do a particular job at the soil–aggregate interface. For a site team, the important checks connect that job to the product supplied and the condition of the fabric as it is covered. Understanding the function makes those checks more useful.
Two functions at the same interface
Separation keeps adjacent materials from intermixing. A geotextile between a pavement’s aggregate layer and the underlying soil helps maintain that boundary. The US Federal Highway Administration (FHWA) explains that a separator also needs appropriate filtration characteristics and enough durability to survive construction. [1]
Filtration allows water movement while retaining soil. Successful selection balances retention, flow and resistance to clogging, using the grading and permeability of the material beside the fabric. Choosing a fabric simply because its openings look small does not establish that balance. [1]
FHWA notes that both woven and non-woven geotextiles have been used for separation. [1] The featured photograph shows different fabric structures; the appearance of a sample does not establish its suitability for a particular road, drain or soil.
Read strength and filtration separately
Queensland Transport and Main Roads’ MRTS27 treats strength class and filtration class as distinct requirements. Its survivability assessment relates to installation stresses, with factors including the construction method, ground condition and backfill material. [2]
For procurement, turn the design requirement into a clear product check. Identify the intended application, the specified properties and the evidence that the proposed grade meets them. A familiar product name or a sample that feels substantial should prompt a document check, rather than settle the selection.
Keep a record of any proposed substitution and the basis for its acceptance. That gives the receiving and installation teams a clear answer when a different-looking roll arrives, without asking them to decide product equivalence from its packaging or colour.
Keep the roll identifiable and protected
Geofabrics’ Bidim Green installation guide provides a useful manufacturer example: roll labels identify the grade, dimensions and unique roll number, while additional markings identify joins and the dispensing direction. [3] Read the instructions for the actual product supplied, including any features that affect how a roll will be deployed.
The same guide recommends storage off the ground with protection from exposure, prompt covering after deployment and care to prevent damage when handling fabric over rough surfaces. It also warns that installation damage can affect strength and filter properties. [3]
Record the roll identity before the packaging is discarded and link it to the installation area. Where several grades are on site, make their intended locations clear to the crew. This is particularly useful when deliveries serve both drainage and earthworks activities.
Install for continuous coverage
MRTS27 requires ground preparation that removes protruding sharp objects and large stones, installation without excessive wrinkles, and joints that retain the specified overlap during later work. Defects, tears and punctures need an appropriate repair that preserves performance, or replacement with conforming material. [2]
For work governed by that specification, construction equipment must not travel directly on the laid fabric; the specified initial cover comes first. [2] Plan how the covering operation will advance so that the fabric, joints and repaired areas remain visible for the required checks.
Geofabrics likewise directs placement procedures to the project specification, including preparation, cover material, lift thickness and equipment requirements. [3] Confirm those details before deployment. Conditions such as slopes, wind or underwater placement need the relevant design and installation arrangements.
Before an area is covered, a useful inspection record identifies the location, product, joint arrangement and any damage or repair. Include photographs where they help explain an otherwise hidden detail. Resolve an uncertain joint or damaged area while the crew can still see and access it.
Confirm the document edition
On 2 November 2026, Austroads lists ATS 2160 Edition 1.2, published on 1 October 2026, for geotextiles used in separation and filtration. [4] The Queensland MRTS27 document used here is dated March 2025. [2] Confirm the contract’s applicable edition and road-authority amendments before adopting requirements; document numbers alone do not identify the complete set of project obligations.
Sources
[1] FHWA — Geotechnical Aspects of Pavements Reference Manual, section 7.2.16.
[2] Queensland Transport and Main Roads — MRTS27 Geotextiles (Separation and Filtration), March 2025.
[3] Geofabrics Australasia — Bidim Green storage and installation guide; manufacturer-specific guidance.
[4] Austroads — ATS 2160 publication and edition record. Sources checked 2 November 2026.
Featured photograph: Geotextile fabric samples, with a pen for scale. Photo: Marilyn475 / Wikimedia Commons (public domain).
