Traditional 28-day testing remains a baseline method, and its use and acceptance vary across countries. As construction demands increase and temperature variability becomes a key factor, real-time monitoring using the maturity method offers a more accurate way to assess in-place concrete strength. The maturity method now is being widely adopted and is recognized globally as an accepted practice within many national and international standards.
In this blog, learn more about concrete maturity, the maturity method, the standards framework, and the codes that apply across different regions.
What Is Concrete Maturity? The Science Behind the Method
The concrete maturity definition is straightforward: the combined age and temperature history correlating directly to strength development.
Traditional age-based methods assume concrete reaches certain strength after a fixed number of days. Temperature, however, has a measurable effect on strength gain.
The hydration process— the chemical reaction between cement and water that creates strength—accelerates at higher temperatures. According to the ASTM C1074, concrete cured at 86°F (30°C) gains strength significantly faster than identical mix cured at 50°F (10°C).
The maturity method quantifies this temperature-driven variation.
The Two Maturity Calculation Methods
Concrete maturity is determined using two accepted calculation methods, each designed to correlate temperature exposure with strength development.
1. Nurse-Saul Function (Temperature-Time Factor)
The Nurse-Saul function uses a simple linear relationship.
Formula:
M(t) = Σ(Ta − T0)Δt
Where:
- M(t) = maturity index
- Ta = average concrete temperature
- T0 = datum temperature (typically −10°C for portland cement)
- Δt = time interval
Example:
Concrete at 20°C for 24 hours with datum temperature of −10°C produces maturity of 720 degree-hours.
(20 − (−10)) × 24 = 720.
This straightforward calculation makes Nurse-Saul common in North America.
2. Arrhenius Equation (Equivalent Age)
The Arrhenius method uses exponential calculation and provides improved accuracy at extreme temperatures.
General guidance:
- Use Nurse-Saul for standard conditions
- Use Arrhenius for extreme or highly variable temperatures
Recognized Standards Governing Concrete Maturity
Several recognized standards define how the maturity method should be applied, ensuring consistent procedures for calibration, measurement, and strength estimation.
ASTM C1074: The Foundation Standard
ASTM C1074 is the internationally recognized maturity standard.
The standard provides procedures for:
- Developing strength-maturity relationships
- Measuring temperature history
- Calculating maturity indices
- Estimating in-place strength
Calibration requires a minimum of three specimens tested at three ages (nine cylinders total), matching field mix design exactly.
Calibration specimens must use the same:
- Materials
- Proportions
- Admixtures
Cure specimens under controlled conditions and test at different ages (commonly 1, 3, and 7 days) to create the strength-maturity curve.
ASTM C1074 applies to concrete containing portland cement or blended cements. Concrete with high percentages of pozzolanic materials may require additional validation.
ACI Guidance: Practical Implementation
The American Concrete Institute offers guidance on in-place testing methods through ACI publications.
ACI provides recommendations on:
- When maturity is appropriate
- Required equipment
- Interpreting in-place strength data
Maturity should supplement, not replace, standard acceptance testing. Verification with periodic cylinder breaks is recommended.
ISO Standards: International Framework
ISO establishes international guidelines for concrete testing and quality control. Many European countries use ISO standards in conjunction with EN standards.
Regional Standards: Where Your Projects Need Compliance
Different countries and jurisdictions reference different standards, making it necessary to understand how maturity is recognized in each region. Let’s take a look at the frameworks used globally.
North America
United States
ASTM C1074 is widely referenced in the U.S., including in ACI 318 Building Code Requirements for Structural Concrete.
State DOT adoption is extensive:
- Texas DOT permits maturity for early strength assessment with ASTM C1074 compliance.
- California DOT Construction Manual allows maturity for early formwork removal.
- New York and Florida DOTs include maturity provisions.
Maturity is commonly used for accelerated bridge construction.
Canada
Canadian standards reference ASTM C1074 through CSA A23.1/A23.2. Provincial permitting includes:
- Ontario Ministry of Transportation
- Alberta Transportation
- British Columbia’s Ministry of Transportation
Maturity is especially beneficial in cold-weather concreting.
Europe and United Kingdom
EN 13670 Execution of concrete structures and EN 206 Concrete specification reference maturity as an acceptable method.
Individual countries adopt these EN standards into national codes (Germany’s DIN, France’s NF).
In the UK, BS EN 13670+A1:2017 and BS 8500 allow maturity monitoring.
Middle East and Gulf Region
Relevant codes include:
These reference ASTM, ACI, and BS standards and permit maturity monitoring with proper documentation. Other Gulf Cooperation Council (GCC) countries follow similar patterns: Saudi Arabia, United Arab Emirates, Qatar, Kuwait, Oman, and Bahrain reference international standards in their building codes.
High ambient temperatures make maturity particularly valuable in this region.
Asia-Pacific
- Standards Australia AS 3600 permits maturity monitoring, commonly used in precast.
- Japan and South Korea reference international maturity practices, especially in infrastructure and large projects.
Tropical climates benefit from maturity due to temperature-driven hydration effects.
How Maturity Monitoring Works in Practice
Modern monitoring uses embedded sensors to measure internal concrete temperature.
Wireless systems such as SmartRock® maturity meters provide:
- Battery life of 30–60 days
- ±0.5°C temperature accuracy
Typical workflow:
- Install sensors during placement
- Record temperature automatically
- Software calculates maturity index
- System indicates when target strength is reached
- Data stored for QA/QC documentation
Platforms like Giatec 360™ provide real-time access and reporting.
Calibration Requirements
ASTM C1074 requires:
- Field-matched mix design
- Minimum nine cylinders
- Embedded temperature sensors
Test at three ages (1, 3, 7 days). Measure strength using ASTM C39 and plot strength versus maturity.
A minimum R² value of 0.95 is expected for curve quality.
Field Application Best Practices
- Install sensors in representative, interior locations
- Use multiple sensors for large elements
- Document installation
- Compare field maturity to calibration curve for strength estimates
- Conduct periodic verification cylinder breaks
Benefits of Standards-Based Maturity Monitoring
Applying the maturity method within a recognized standards framework strengthens quality control and decision-making. Here is a closer examination of the advantages.
Schedule Advantages
- Earlier formwork removal
- Improved cycle times
- Reduced heating duration in winter
Cost Savings
- Lower formwork rental
- Reduced labor and energy
- High-rise projects often gain 2–4 days per floor
Quality Control
- Data-driven decision-making
- Automated recordkeeping
Risk Reduction
- Early identification of slow strength gain
- Reduced likelihood of premature loading
Common Questions About Maturity Standards
Do I need regulatory approval?
Public agencies may require approval. Private projects typically follow structural engineer guidance.
Can maturity replace cylinder testing?
No. It supplements acceptance testing.
What if the mix design changes?
New mix designs require new calibration unless adjustments are minimal.
Does maturity work with all cement types?
Portland and blended cements work well. High SCM content may require additional steps.
Getting Started with Maturity Monitoring
Recommended steps:
- Verify local code provisions
- Select a qualified laboratory
- Choose sensor technology
- Train field crews
- Establish data protocols
- Coordinate with the structural engineer
Conclusion
Concrete maturity represents the combined effect of time and temperature on strength development, providing a reliable way to assess in-place performance. Global standards, including ASTM, ACI, EN, ISO, and regional codes, offer the structured framework needed for consistent application. With proper calibration, verification, and the use of modern technology like wireless sensors that capture accurate real-time temperature data, maturity monitoring delivers dependable results that enhance scheduling, quality control, and overall construction efficiency.
