Standards Australia · Published 2007

AS 1379:2007

Specification and Supply of Concrete

AS 1379:2007 specifies the requirements for the production and supply of normal-class and special-class concrete, including the specification methodology, quality acceptance criteria, sampling and testing procedures, and certification requirements for concrete producers. The standard defines normal-class concrete by characteristic compressive strength (N20, N25, N32, N40, N50, N65), maximum aggregate size, slump and exposure classification, and specifies the production-process and quality-control requirements that producers must meet to supply concrete certified to AS 1379. It also covers special-class concrete (high-strength, high-flow, fibre-reinforced, lightweight, and other engineered mixes) where specification beyond the normal-class envelope is required, and prescribes the certification body framework (typically through National Association of Testing Authorities, NATA) for testing laboratories. AS 1379 is the controlling reference for concrete supply in Australia and is referenced from AS 3600 (concrete structures), AS 3735 (liquid-retaining concrete), AS 5100.5 (bridge concrete), and AS 1012 series (concrete test methods) as the source-side quality basis. The 2007 edition replaced AS 1379-1997 and incorporated updated quality-acceptance methodology and special-class concrete provisions. Amendments have been issued covering specific high-performance concrete provisions.

TRSC Engineering Interpretation

AS 1379 is rarely directly applied in TRSC's existing-asset capacity assessment, because the standard governs concrete supply at the time of construction rather than residual-property assessment. However, the standard becomes decision-controlling in three categories of TRSC engagement: remediation specification (where new concrete is supplied as part of the remediation), forensic assessment of construction-defective concrete (where the as-supplied concrete did not meet specification), and continuing-life material characterisation (where measured residual properties are compared against the as-supplied AS 1379 specification). Three application points matter when AS 1379 is relevant. First, TRSC remediation specifications for repair concrete reference AS 1379 normal-class designations as the basis for ordering — typically N40 or N50 for structural repairs with appropriate exposure classification. The remediation specification documents not only the AS 1379 normal-class but also any special-class provisions (typically reduced shrinkage, increased flow, or fibre reinforcement for repair-specific applications) and the AS 1379 testing requirements at the supply point. The Sika Sikadur 32-N bonding-agent specification used on the 12 Creek Street and Marina Mirage projects, for example, is paired with AS 1379 N50 repair concrete with explicit slump and shrinkage acceptance criteria documented in the Form 15 file. Second, forensic assessment of construction-defective concrete relies on AS 1379 as the at-supply specification benchmark. TRSC has been engaged on several disputes where the as-supplied concrete did not meet AS 1379 normal-class strength (typically due to water addition at site, improper mix-design or quality-control failure at the producer), and the assessment requires comparing measured-core compressive strength against the AS 1379 normal-class characteristic strength accounting for the documented sampling and testing methodology. Where the measured strength falls below the AS 1379 acceptance threshold, the assessment quantifies the structural-capacity impact and prescribes remediation. Third, continuing-life material characterisation under AS 5100.5 Section 14 or AS 3600 measured-property assessment uses AS 1379 normal-class characteristic strength as a reference point for comparison. The assessment compares measured residual compressive strength (from extracted cores tested per AS 1012.14) against the AS 1379 design-intent characteristic strength, and where the measured strength materially differs from the design-intent value, the engineering basis for the residual-property assessment is documented in the investigation file. Pre-1980 concrete frequently shows measured residual strength materially higher than the design-intent value (due to ongoing hydration over decades), which can support increased capacity calculation and reduced remediation scope.

Form 15 RPEQ Certification Implications

TRSC Form 15 certifications for remediation completion reference AS 1379:2007 as the supply-side specification basis for any new concrete used in the remediation. The Form 15 file retains the AS 1379 normal-class specification, the supply-point test results (slump, density, plastic-state checks), the cube or cylinder test results at 7 and 28 days against AS 1379 acceptance criteria, and the curing and finishing methodology applied. Where the remediation includes special-class concrete provisions (low-shrinkage, fibre-reinforced, increased flow), the Form 15 documents the special-class specification and supplementary testing performed. For continuing-life recertification of existing concrete structures, the Form 15 references the as-supplied AS 1379 specification (where documented) and the measured residual properties from the investigation, with the engineering basis for any deviation from design-intent values.

Frequently Asked Questions

Engineering questions about AS 1379:2007

What is AS 1379 normal-class concrete?
AS 1379 normal-class concrete is specified by characteristic compressive strength (N20, N25, N32, N40, N50, N65), maximum aggregate size, slump, and exposure classification. The producer is responsible for the mix design that achieves the specified characteristic strength under AS 1379 quality-control requirements. Normal-class designations are the default for structural concrete and cover the vast majority of building and bridge applications. Special-class concrete is used where requirements beyond the normal-class envelope are needed — typically high-strength (above N65), high-flow (slumps over 200 mm without segregation), fibre-reinforced (steel or polypropylene fibre additions), or low-shrinkage formulations for repair applications.
How is forensic assessment of defective concrete conducted?
Forensic assessment of construction-defective concrete starts with the as-supplied AS 1379 specification, which is the producer's certification that the concrete meets the specified strength under AS 1379 quality-control. TRSC compares the measured-core compressive strength (extracted per AS 1012.14 and tested at NATA-certified laboratory) against the AS 1379 normal-class characteristic strength accounting for the standard's sampling and testing methodology — the characteristic strength is the lower-95-percentile value, not the mean. Where the measured strength falls below the AS 1379 acceptance threshold (after appropriate statistical treatment), the as-supplied concrete is non-compliant, and the structural-capacity assessment quantifies the implication. Common causes of non-compliance are water addition at site, improper mix-design, quality-control failure at the producer, and sampling-and-curing errors during certification.
Why does pre-1980 concrete sometimes test stronger than its design-intent specification?
Pre-1980 concrete frequently shows measured residual strength materially higher than the design-intent characteristic strength, primarily because of ongoing hydration over decades. Concrete continues to gain strength after 28 days under sustained moist conditions; pre-1980 concrete in protected exposure (interior, dry environment) can show 28-day-equivalent strengths 30 to 60 percent higher than original design-intent at age 40 to 60 years. For existing-asset capacity assessment, this is decision-controlling — applying AS 3600 capacity equations to the measured residual strength frequently demonstrates adequate capacity that the design-intent calculation would not. The investigation must include extracted-core compressive strength testing under AS 1012.14 with appropriate statistical treatment, and the Form 15 file documents the basis for using measured rather than design-intent strength.
Sources & Further Reading