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.
Maturity Sensing System can be used to monitor the temperature profile of fresh and hardened concrete.
This can provide information on: