Non-adhesive Prestressed Steel Strand Testing Service for Global Infrastructure Projects
As an ISO/IEC 17025 accredited laboratory, we deliver a rigorous non-adhesive prestressed steel strand testing service that verifies the mechanical strength, relaxation behavior, dimensional accuracy, and corrosion protection integrity of unbonded prestressing steel. Our non-adhesive prestressed steel strand testing service supports manufacturers and exporters of monostrand and multi-strand tendons who must demonstrate compliance with ASTM A416, EN 10138, ISO 6934, and regional construction codes across the European Union, North America, the Middle East, and Asia. Every test is conducted under our CNAS-accredited quality system, producing reports accepted by notified bodies, infrastructure engineering consultants, and procurement authorities worldwide.
Product Samples We Regularly Test in Our Non-adhesive Prestressed Steel Strand Testing Service
- Seven-wire low-relaxation prestressing steel strands — 12.7 mm, 15.2 mm, and 15.7 mm nominal diameters for post-tensioning and pre-tensioning
- Non-adhesive monostrand tendons with corrosion-inhibiting grease and PE sheathing — for building slabs, bridge decks, and ground anchors
- Multi-strand unbonded tendons for nuclear containment and LNG tank construction — assembled bundles with individual strand protection
- Flat and oval duct non-adhesive prestressing systems — for thin slabs and transverse bridge post-tensioning
- Galvanized and epoxy-coated prestressing steel strands — for aggressive marine and chemical plant environments
- High-strength and extra-high-strength prestressing steel grades — with specified characteristic tensile strengths up to 2160 MPa
Core Mechanical Testing in Our Non-adhesive Prestressed Steel Strand Testing Service
- Tensile testing at ambient temperature per ASTM A370, ISO 6892-1, and EN ISO 15630-1 — the complete strand specimen is pulled to failure on a calibrated universal testing machine with hydraulic grips to measure the 0.2% proof stress, the maximum force, and the percentage elongation at maximum force, verifying that the non-adhesive prestressed steel strand meets the characteristic tensile strength and ductility class required by the project specification.
- Determination of the modulus of elasticity per ASTM A416 and ISO 6934-3 — the slope of the stress-strain curve is calculated from the linear portion of the tensile test data to confirm the strand stiffness used in the structural design for prestress loss calculations.
- Isothermal stress relaxation test at 1000 hours per ASTM A416, EN 10138-2, and ISO 15630-3 — the strand is tensioned to 70% or 80% of its actual maximum force and the load loss is monitored over 1000 hours at a constant temperature of 20 °C, providing the guaranteed relaxation value that ensures the long-term prestressing force in the structure remains above the design limit.
- Fatigue and cyclic loading performance per ISO 15630-1 and EN 1992-1-1 — the strand is subjected to two million load cycles between defined upper and lower stress limits to verify the fatigue endurance required for bridge and dynamically loaded structures.
- Deflected tensile test for strand anchorage efficiency per ASTM A981 and EN 13391 — the strand is tested in a wedge anchorage assembly to confirm that the static tensile strength of the anchor-strand system exceeds 95% of the strand's actual maximum force.
- Axial stiffness and load-elongation curve of the complete non-adhesive tendon assembly — the monostrand with its sheathing and grease is tested to generate the overall stiffness that governs the elastic shortening and elongation calculations during stressing operations.
Chemical Composition and Material Verification in Our Non-adhesive Prestressed Steel Strand Testing Service
- Optical emission spectrometry for alloy and grade verification per ASTM E415 and ISO 14284 — the carbon, manganese, silicon, and residual element content of the prestressing steel is quantified to confirm the wire rod material conforms to the specified high-carbon steel grade and that no tramp elements are present that could embrittle the strand.
- Decarburization depth and surface condition per ISO 16120-4 and ASTM A416 — the cross-section of the individual wire is examined metallographically to measure the depth of any partial decarburization, ensuring that the surface hardness and fatigue resistance meet the minimum requirements for the non-adhesive prestressed steel strand.
- Hydrogen embrittlement susceptibility testing per ASTM F519 and customer protocols — the high-strength steel is evaluated for sensitivity to hydrogen-induced delayed fracture, a critical safety requirement for prestressing steel that operates under sustained high tensile stress in humid or corrosive environments.
Sheathing, Grease, and Corrosion Protection Inspection for Non-adhesive Prestressed Steel Strands
- Polyethylene sheathing thickness, tensile strength, and elongation per ISO 6259-3 and ASTM D638 — the extruded PE jacket that encases the strand and corrosion-inhibiting grease is mechanically tested to verify it withstands the handling, coiling, and installation abrasion without perforation that would expose the strand to moisture.
- Corrosion-inhibiting grease quantity, consistency, and water resistance per ASTM D1264 and internal protocols — the mass of grease per unit length is measured, and the grease is tested for oxidation stability, drop point, and resistance to water washout to confirm it provides the specified long-term corrosion protection for the non-adhesive prestressed steel strand.
- Sheathing continuity and leak tightness by spark testing per ASTM D6956 — the complete PE jacket is subjected to a high-voltage spark test to detect any pinholes or discontinuities that would provide a pathway for water and chloride ingress to the prestressing steel.
- Stress corrosion cracking resistance of the strand in a simulated pore solution per ASTM G129 and customer protocols — the tensile-loaded strand is exposed to a hot alkaline solution with chlorides to verify it does not crack or fail under conditions representative of the concrete environment.
- Neutral salt spray and cyclic corrosion resistance per ISO 9227 and ASTM B117 — the complete non-adhesive tendon sample is exposed to salt fog and the strand ends, anchorages, and sheath transitions are inspected for red rust and pitting to confirm the corrosion protection system remains intact under marine and de-icing salt conditions.
Dimensional, Surface, and Visual Quality Inspection of Non-adhesive Prestressed Steel Strands
- Strand diameter, wire diameter, and lay length measurement per ASTM A416 and ISO 15630-1 — laser micrometers and precision callipers verify that the strand geometry conforms to the nominal dimensions within the specified tolerances, ensuring correct fit in anchor wedges and consistent prestressing force transfer.
- Surface defect detection by eddy current and visual inspection per ASTM E426 and ISO 10893-2 — encircling coil eddy current systems scan the individual wires at the stranding line to detect surface-breaking seams, laps, and slivers that would cause fatigue crack initiation in the finished non-adhesive prestressed steel strand.
- Straightness, coil set, and cast measurement per ASTM A416 — the natural curvature and twist of the strand are measured to verify the strand does not exhibit excessive camber that would cause handling difficulties or tendon misalignment in the duct during installation.
Report Recognition and ISO/IEC 17025 Compliance
All test methods described in this non-adhesive prestressed steel strand testing service are covered by our ISO/IEC 17025 scope of accreditation. Our test reports and certificates are accepted by European notified bodies for CE marking of prestressing steel under the Construction Products Regulation, by North American bridge and building authorities referencing ASTM and AASHTO standards, and by infrastructure project procurement teams across the Middle East, Australia, and Asia. Whether you require a full qualification dossier for a new unbonded tendon system, a batch release inspection for an export shipment, or a root cause failure analysis of a strand rupture, our laboratory provides the measurement accuracy and prestressing technology expertise that the global post-tensioning industry demands.
