Can Maturity Be Trusted?
The quick answer? Yes. Yes it can.
If you’re still unconvinced though, feel free to read on.
The Maturity Method is used to link the heat output of concrete and its strength development. This method makes it possible to calculate the compressive strength of a concrete slab based on its temperature.
To read more on the history of the Maturity Method, and how it differs from the traditional method of cube crushing, request a white paper here.
There are a number of standards which regulate and outline the compliant and accurate use of the Maturity Method. Following is a brief overview of some of those standards and their components:
ASTM- C1074 published in 1987 (international)
ASTM International was founded in 1898, and is an international standard organisation which develops technical standards for a wide range of materials and systems. ASTM International has published almost 13,000 such standards to date. ASTM-C1074 is an international standard which formalises the use of the maturity method on site.
The ASTM-C1074 standard describes two alternative equations that can be used to reach a correlation between concrete temperature and strength. Although the names of these equations are not mentioned in the standard, they are commonly known as the Nurse-Saul function, and the Arrhenius function.
There are many criteria to properly measure the temperature of the concrete included in the ASTM-C1074 standard, such as: temperature sensors connected to data-loggers, and embedded digital devices that measure, record, and store temperature data. In addition, the time interval between temperature measurements are required to be 30 minutes or less.
The ASTM-C1074 standard also outlines the proper procedure of estimating in-situ strength. For instance, the sensor must be secured within the section to be cast before concrete placement, or embedded into the fresh concrete as soon as practicable. The sensor must also be completely surrounded by concrete.
BS EN 13670:2009 (UK)
The British Standards Institution is the national standards body of the United Kingdom. This organisation publishes standards on a wide range of products and services. BS EN 13670:2009 is the British standard for the execution of concrete structures that formalises the use of the Maturity Method on site.
The BS EN 13670:2009 standard recognizes maturity testing as a valid form of estimating compressive strength of in-situ concrete, although no specific functions are mentioned in the standard.
In fact, this standard does not go into in-depth detail regarding the relevant criteria and procedures at all, rather it uses broad language such as ‘methods of established suitability.’. The purpose then of maturity in this standard is only to sanction it as a suitable method of estimating compressive strength.
Although various institutions choose to characterise the criteria and parameters for the use of maturity differently, the method itself is one that is internationally recognised for estimating the compressive strength of concrete. The worlds largest construction companies are already relying on it to achieve more accurate strength data on their in-situ concrete.
If they can trust it, so can you.