The Concept of Maturity Method
The maturity method is a technique to account for the combined effects of time and temperature on the strength development of concrete. The method provides a relatively simple approach for making reliable estimates of in-place strength during construction.
Take a tour through the Development of In-place Concrete Testing.Why use Maturity Method?
- The maturity method is a technique to account for the combined effects of time and temperature on the strength development of concrete. The method provides a relatively simple approach for making reliable estimates of in-place strength during construction. The origin of the method can be traced to work on steam curing of concrete carried out in England in the late 1940s and early 1950s.
- The maturity method is a technique that allows the in-place concrete strength to be estimated using the time and temperature history of freshly placed concrete.
- Maturity methods are used as a more reliable indicator of the in-place strength of concrete during construction in lieu of testing field-cured cube/cylinder specimens.
- The traditional approach of using field-cured cube/cylinder specimens does not replicate the same temperature profile of the in-place concrete and likely does not estimate its in-place strength as accurately with maturity methods strength information is provided in real-time since maturity measurements are made on-site at any time.
- Construction workflow is optimized, and construction activity timing can be based on more accurate in-place strength information.
- The procedure for estimating concrete strength using maturity concepts is described in ASTM C 1074, Standard Practice for Estimating Concrete Strength by the Maturity Method. The temperature-time-strength relationship of a concrete mixture is developed in laboratory tests. This establishes one of the two maturity functions for that mixture. During construction a maturity index is determined from measured temperature and age. The maturity index is used to estimate the in-place strength from the pre-established maturity-strength relationship.
Advantages of Maturity Methods
- Field implementation of the maturity concept and procedures is simple
- Insures that strength of concrete meets specifications, if the procedure is followed correctly
- Provides instant predictions of in-place strength
- Maturity sensor enables strength measurement more representatively
- The sensor can be placed at critical locations to precisely determine the strength at a given location
- Provides a continuous monitoring and measurement of strength gain
- Strength estimation not affected by external factors such as improper sample preparation, capping procedures, or loading rates on the sample, etc.
- Significant time and money savings can be achieved in construction through:
- Removal of shoring, formwork, etc. at appropriate time based on maturity
- & Cold weather protection
- Determination of proper time for loading, saw cutting, or opening for service
- Acceptance of the concrete (QA/QC)
Limitations of Maturity Methods
- Brand of cement
- Source and Class of fly ash
- Source of aggregates
- Water to cement ratio
Maturity Sensing System
The system consists of a range of sensors and which measure and record physical properties of in-place concrete, a reader which is used to communicate with sensors and comprehensive software solutions to effectively analyze job-site information and communicate that information effectively. This innovative design allows a single reader to be used simultaneously with an unlimited number of sensors.
Maturity Sensing System utilizes – and optimizes – the maturity method, adopted as an industry standard by ASTM, ACI, NIST, and others, offering real advantages over traditional cylinder testing and other maturity products.
- More accurate than lab- or field-cured PCC test specimens
- Real-time data display for faster decisions. No waiting for 2, 3, or 7-day breaks.
- Continuous measurement and recording of temperature
- A complete system for worksite and office convenience
- Rugged Sensors protected by casing and surrounding concrete
- Easy data sharing to other devices like computer
- Portable handheld for easy on-site data download anywhere, at any time. No need to carry computers around the job site
How it is Used
Before construction begins, a set of test specimens are cast, out of them some with the maturity sensors embedded, to plot the relationship between compressive strength and maturity (degrees Celsius – hours) for the specified mix design. At standard intervals – 1, 2, 4, 7, and 14 days – strength and maturity are measured. Results are presented graphically, known as “Calibration Curve”.
How it Works
Maturity Sensing System is a complete system, designed for convenience and ease of use. And it’s engineered to stand up to the rugged conditions of heavy construction sites.
The system includes:
A. Maturity Sensors / Loggers
Maturity Sensors, contain a long-life battery, microprocessor, memory, and thermistor. Placed in concrete while casting, Sensors continuously calculate and store concrete maturity data. A tough casing protects the intelligent electronics inside.
B. Reader / Software
The handheld Reader is used to communicate with embedded Sensors. Workers simply connect Sensors and use the Reader to view and download maturity data.
4 easy steps to measure temperature or strength:
Maturity Sensing System can be used to monitor the temperature profile of fresh and hardened concrete.
This can provide information on: