Concrete and aggregate testing ensures that construction materials meet the specified quality, strength, and durability requirements for their intended application.
In Australia, testing is governed by the AS 1012 series (concrete) and AS 1141 series (aggregates).
Concrete Testing
Fresh Concrete Tests
| Test | Standard | Purpose | Measurement |
|---|---|---|---|
| Slump test | AS 1012.3.1 | Workability assessment | mm (0–250 mm typical) |
| Compacting factor | AS 1012.3.2 | Workability (low slump) | Ratio |
| Air content | AS 1012.4.3 | Air entrainment verification | % by volume |
| Temperature | AS 1012.4.1 | Temperature compliance | °C |
| Density | AS 1012.5 | Fresh density verification | kg/m³ |
| Mass per unit volume | AS 1012.5 | Yield verification | kg/m³ |
Slump Test Procedure (AS 1012.3.1)
The most widely used test for fresh concrete workability:
| Slump (mm) | Workability | Typical Application |
|---|---|---|
| 0–25 | Very low | Precast, slipforming |
| 25–50 | Low | Pavements, mass concrete |
| 50–100 | Medium | Reinforced concrete slabs, beams |
| 100–150 | High | Heavily reinforced sections |
| 150–200+ | Very high / flowing | Pumped concrete, congested reinforcement |
Hardened Concrete Tests
| Test | Standard | Purpose |
|---|---|---|
| Compressive strength | AS 1012.9 | Concrete grade verification |
| Indirect tensile strength | AS 1012.10 | Cracking resistance |
| Flexural strength | AS 1012.11 | Pavement concrete design |
| Drying shrinkage | AS 1012.13 | Long-term deformation |
| Water absorption | AS 1012.21 | Durability indicator |
| Chloride penetration | AS 1012.20 | Durability, corrosion risk |
| Sulfate resistance | AS 1012.20 | Chemical attack resistance |
Compressive Strength Testing (AS 1012.9)
The primary quality control test for concrete:
| Grade | f'c (MPa) at 28 days | Typical Application |
|---|---|---|
| N20 | 20 | Blinding, non-structural fill |
| N25 | 25 | House slabs, footings |
| N32 | 32 | General reinforced concrete |
| N40 | 40 | Commercial slabs, columns |
| N50 | 50 | High-rise, prestressed |
| N80+ | 80+ | High-performance, precast |
Testing frequency:
- 1 set of 3 cylinders per 50–100 m³ of concrete
- Minimum 1 set per day per grade
- Tested at 7 days (indicative) and 28 days (specified)
Concrete Sampling
| Sample Type | Use | Standard |
|---|---|---|
| Cylinders (100 × 200 mm) | Compressive strength | AS 1012.8 |
| Cylinders (150 × 300 mm) | Compressive strength (large aggregate) | AS 1012.8 |
| Beams | Flexural strength | AS 1012.8 |
| Cores | In-situ strength assessment | AS 1012.14 |
Aggregate Testing
Physical Properties
| Test | Standard | Purpose | Typical Range |
|---|---|---|---|
| Particle size distribution | AS 1141.11 | Grading compliance | % passing each sieve |
| Particle density | AS 1141.4 | Specific gravity | 2.4–2.8 t/m³ |
| Water absorption | AS 1141.5 | Porosity indicator | 0.5–4% |
| Shape (flakiness index) | AS 1141.14 | Particle shape | 0–35% |
| Voids | AS 1141.4 | Packing characteristics | 30–45% |
Mechanical Properties
| Test | Standard | Purpose | Acceptable Range |
|---|---|---|---|
| Los Angeles abrasion | AS 1141.23 | Wear resistance | < 30% (base course) |
| Aggregate crushing value | AS 1141.21 | Crushing resistance | < 25% (base course) |
| Wet-dry strength variation | AS 1141.22 | Weathering resistance | < 35% variation |
| 10% fines value | AS 1141.22 | Crushing under load | > 150 kN |
| Point load index | AS 4133.4.2.1 | Rock aggregate strength | > 1.5 MPa |
Durability Properties
| Test | Standard | Purpose | Acceptable Limit |
|---|---|---|---|
| Soundness (MgSO₄) | AS 1141.24 | Freeze-thaw resistance | < 10% loss |
| Alkali aggregate reactivity | AS 1141.60 | ASR (alkali-silica reaction) risk | Expansion < 0.10% |
| Organic impurities | AS 1141.3 | Organic matter content | Colour less than standard |
Field Testing
Concrete Field Testing
- Slump testing on every truck (or per specified frequency)
- Temperature measurement
- Cylinder moulding for compressive strength
- Curing on-site (temperature-controlled water tanks)
In-Situ Concrete Testing
| Test | Standard | Purpose |
|---|---|---|
| Schmidt hammer | AS 1012.14 | Surface hardness (core correlation) |
| Ultrasonic pulse velocity | AS 1012.21 | Uniformity, honeycombing |
| Core drilling | AS 1012.14 | In-situ strength |
| Covermeter | AS 1012.21 | Reinforcement cover |
QA/QC Program
Pre-Construction
- Aggregate source approval (quarry compliance testing)
- Concrete mix design with trial batching
- Specification compliance review
During Construction
| Material | Test Frequency | Acceptance Criteria |
|---|---|---|
| Concrete | 1 set per 50–100 m³ | f'c ≥ specified strength |
| Coarse aggregate | Per 5,000 t source | Grading, LAA, AAV within spec |
| Fine aggregate | Per 2,000 t source | Grading, silt content |
| Imported fill | Per material source | Grading, compaction, plasticity |
Post-Construction
- Core testing for verification
- Ultrasonic tomography (if defects suspected)
- Compliance report
Australian Standards
| Standard | Title |
|---|---|
| AS 1012 Series | Methods of testing concrete |
| AS 1141 Series | Methods for sampling and testing aggregates |
| AS 1379 | Specification and supply of concrete |
| AS 2758.1 | Aggregates for concrete |
| AS 2758.2 | Aggregates for sprayed concrete |
| AS 2758.5 | Aggregates for railway ballast |
| AS 2758.6 | Aggregates for unbound pavement materials |
| AS 3600 | Concrete structures |
| AS 5100.5 | Bridge design — concrete |
Frequently Asked Questions
How often should concrete be tested?
Standard practice is 1 set of strength cylinders per 50–100 m³ of concrete placed, with at least 1 set per day for each concrete grade.
What is the difference between 7-day and 28-day strength?
Concrete typically reaches 65–80% of its 28-day strength at 7 days, depending on cement type and curing conditions. The 7-day result is indicative; 28-day is the specification compliance test.
Can aggregate from different sources be mixed?
Yes, but each source must be tested individually and the blended grading must meet specification requirements.
What is the acceptable slump for pumped concrete?
Pumped concrete typically requires a slump of 100–160 mm, depending on pump type, line diameter, and pumping distance.