Raising the Standard in Post-Tensioning: Governance, Verification and Engineering Discipline
Interspan outlines the systems, accreditation and engineering controls that differentiate its post-tensioning services, including CARES APT04 certification, system-tested anchorage, full traceability and structured grout verification.
Beyond Compliance: A Structured Approach to Post-Tensioning
In post-tensioning, compliance is essential – but it shouldn’t be the endpoint.
At Interspan, compliance forms the foundation of a broader governance framework built around verification, traceability, independent accreditation and engineering oversight.
Following a recent internal review, our team examined the systems and controls that define how we operate. What emerged was not a single differentiator, but a layered operating model designed to reduce structural risk and support long-term asset performance.
1. System-Tested Anchorage – Verified as an Assembly
Interspan utilises its own in-house post-tensioning anchorage kit, tested as a complete system comprising anchor head, bearing plate and wedges.
Testing has demonstrated compliance with AS 1314 and ETA requirements under EAD 16004-00-0301, including static load transfer and fatigue performance.
Testing components individually does not fully verify system behaviour. By validating the anchorage as an assembled system, performance is confirmed at the level it performs in practice.
2. Active Supply-Chain Governance
Quality control begins upstream. Interspan conducts structured audits of PT kit suppliers to confirm that material properties and critical dimensional tolerances align with specification requirements.
This ensures that compliance is verified through documented oversight, not assumed through declaration.
3. Independent Third-Party Accreditation for Post-Tensioning
Interspan holds CARES APT01 accreditation for the Production and Supply of Post-Tensioning Anchorage Systems and CARES APT04 accreditation for the Supply and Installation of Post-Tensioning Systems in Concrete Structures.
Pre-bagged grout is sourced from manufacturers certified under CARES APT03, providing independent oversight of grout production standards.
These accreditations are subject to ongoing external audit, reinforcing procedural consistency and quality assurance.
4. Full Material Traceability
Interspan’s QA system provides end-to-end traceability from purchase order through receipt, delivery and installation.
Materials installed in each pour can be identified at batch level, a capability that supports risk management, defect investigation and long-term asset governance.
5. Verified Grout Performance – Every Pour
Grout quality is confirmed through structured on-site testing for each pour, including sieve analysis, fluidity testing, density checks and strength verification.
Routine bleed and volume change testing further validate supplier compliance, while a long history of in-house grout strength data demonstrates ongoing conformity with specification requirements.
Durability performance is not assumed. It is measured.
6. Competency-Based Installation Controls
Site operatives are formally trained and assessed, and are issued CARES competency cards detailing their qualification levels.
Quality procedures require each post-tensioning activity to be supervised by an operative at or above a defined competency level. This ensures accountability and consistent installation standards across projects.
7. Integrated Quality, Safety and Environmental Systems
Interspan undergoes regular internal and external audits under ISO 9001 (Quality Management), ISO 45001 (Occupational Health & Safety), ISO 14001 (Environmental Management) and CARES APT04.
These systems operate together to support disciplined project delivery and continuous improvement.
8. Engineering-Led Design – Structured and Reviewed
Design is undertaken in-house and is not outsourced.
All drawings undergo mandatory two-engineer internal review and approval, followed by external review and certification.
This layered review process reduces technical risk, improves constructability and ensures structural intent is preserved through delivery.
A Governance-Led Operating Model
The distinction lies not in a single feature, but in the cumulative effect of disciplined systems: system testing, supplier auditing, independent accreditation, traceability, grout verification, competency controls and structured design review.
Post-tensioning is a critical structural system with long-term performance implications. Interspan approaches it accordingly – with governance, verification and engineering discipline at the core of delivery.
NEW STRUCTURES
The Interspan Group brings unique expertise in post-tensioning, construction methodology, and lifting operations that reduce CO₂ emissions, material usage, and construction program.
Interspan Strengthening & Repair
Interspan uniquely integrates in-house post-tensioning expertise, advanced forensic diagnostics, and cutting-edge strengthening technologies to enable a single-source delivery model trusted by global developers for complex retrofit and reuse projects.
NEW STRUCTURES
The Interspan Group brings unique expertise in post-tensioning, construction methodology, and lifting operations that reduce CO₂ emissions, material use, and construction program duration.
EXISTING STRUCTURES
We specialise in helping clients extend the lifespan of concrete structures through advanced repair, strengthening, and carbon-fibre solutions. Adaptive reuse projects are a perfect fit for our expertise, helping to minimise waste while delivering safe, modern outcomes that support community growth.
Over the last decade, the Interspan Group has become a market leader in the application of CFRP-strengthening solutions, with notable projects including the award-winning The Space House in London and the Quay Quarter Tower in Sydney.
Quality Assurance
Quality Assurance is of immense significance to Interspan because it impacts the safety of our operatives and future occupants, the long-term durability of our structures, and our client satisfaction and relationships.
Interspan is accredited under CARES APTO1 for the Production and Supply of Post-tensioning Anchorage Systems and is the only post-tension contractor in Australia accredited under CARES APTO4 for the supply and installation of Post-tensioning systems in concrete structures.
Sustainability
Post-tensioning and adaptive reuse are powerful design approaches that reduce material use and embodied carbon—delivering more efficient, resilient, and sustainable structures for the future.
Investigation & Diagnosis
Our repair and strengthening approach begins with a thorough investigation and diagnosis of the underlying causes of deterioration.
Destructive Investigation
Using small drill holes, we conduct air compressor testing and endoscopic review to assess internal conditions. GPR is used first to safely locate post-tensioning tendons and embedded reinforcement before any drilling occurs.
Non-Destructive Investigation
Following targeted destructive tests, Impact Echo and other non-destructive methods are used to map voids or defects within partially grouted tendons or concrete elements. This enables precise planning of the remediation process and selection of the most effective grouting and strengthening systems.
In-House Engineering & Design
Every project benefits from Interspan’s in-house engineering and design capability. Our engineers collaborate closely with consulting engineers and asset owners to evaluate all technical and economic factors — including material selection, serviceability, constructability, appearance, and long-term maintenance requirements. This integrated process ensures the proposed solution is not only structurally sound but practical and cost-efficient in operation and upkeep.
