Understanding the Concrete Maturity Curve | Converge.io

October 7, 2023

In the dynamic world of construction, understanding the characteristics of materials used, such as concrete, is crucial. Among the numerous properties of concrete, the concept of concrete maturity and its accompanying maturity curve plays a pivotal role in determining the quality and strength of a construction project. 

This article aims to illuminate what the concrete maturity curve is, its significance in the construction industry, and how to utilise it effectively. Let's start by unpacking the term 'concrete maturity.'

Read more: Can you trust the maturity method and explaining the maturity curve and AI and concrete maturity sensors.

Concrete Maturity: An Overview

In the world of civil engineering, concrete maturity is a crucial concept. It refers to the cumulative measure of heat within the concrete after it's poured. This heat accumulation can predict the strength development of the mix. Essentially, it's about gauging the concrete's "age."

  1. The concept of maturity was first introduced by Nurse-Sahib in 1944.
  2. Maturity is generally expressed in temperature-time units (degree-hours or degree-days).
  3. It is assumed that for a specific concrete mix, there is a unique relationship between maturity and strength.

The Concrete Curing Process

Concrete curing refers to the process that helps maintain adequate moisture and temperature in freshly placed concrete. This is essential to ensure the concrete gains strength and durability. It's a critical stage in any construction project.

  1. Curing involves controlling the moisture content and temperature of fresh concrete.
  2. The primary purpose of curing is to ensure that the concrete hydrates properly.
  3. Curing can be executed through various methods such as wet covering, ponding, or the use of curing compounds.
  4. Concrete gains most of its strength within the first week of curing but continues to harden and get stronger for years.

The Concrete Maturity Curve

The concrete maturity curve illustrates the correlation between maturity and concrete strength. It's an invaluable tool in construction, helping to predict the in-place strength of concrete.

  1. The curve is generated in a lab by preparing a specific concrete mix, curing it under controlled conditions, and periodically testing samples for compressive strength.
  2. The strength test results are plotted against the corresponding maturity values, giving the concrete maturity curve.
  3. This curve can be used on a construction site to predict the in-place strength of concrete.

Read more: We explain the differences between in-situ concrete and lab cured concrete and  discuss the benefits and challenges of cube testing.

Importance of the Concrete Maturity Curve

Understanding the concrete maturity curve is crucial in construction management for several reasons:

1. Time-Efficient: Using the concrete maturity curve, engineers can estimate when a concrete element has reached the desired strength, speeding up the construction process.

2. Cost-Effective: By reducing the need for numerous concrete sample tests, the concrete maturity curve can significantly save on testing costs.

3. Improves Quality Control: The curve helps ensure the desired strength is achieved, enhancing the overall quality of the construction.

4. Facilitates Early Loading: It allows for early formwork removal or load application, based on accurate strength estimations.

Utilising the Concrete Maturity Curve

Using the concrete maturity curve on site involves several steps:

  1. Measure the temperature profile of the in-place concrete over time.
  2. Calculate the concrete's maturity using the recorded temperature profile.
  3. Reference the calculated maturity to the laboratory-generated maturity curve to predict in-place concrete strength.

In essence, the concrete maturity curve offers a reliable and cost-effective method to estimate concrete strength, speeding up construction schedules and enhancing quality control. By integrating the curve into standard practice, constructors can ensure they're building the strongest and most reliable structures.

Read more: We make comparisons between cube testing and cylinder testing as well as between using sensors and cube testing.

A phone with the converge software displaying a chart measuring concrete's temperature and strength
The maturity curve of in-situ concrete read from the ConcreteDNA mobile app

Frequently asked questions

What is the maturity method of concrete strength?

The maturity method of concrete strength is a technique used to predict the early age strength of concrete. This method considers the effects of time and temperature on the strength gain of concrete. 

By integrating these parameters, one can predict the concrete's strength development over time, aiding in efficient planning and control during construction.

Why does concrete need 28 days?

The 28-day period is a standard industry measure for concrete strength, established by many building codes and standards worldwide. It is based on empirical evidence that concrete achieves approximately 95-99% of its strength after 28 days of proper curing under standard conditions (20°C or 68°F). 

What happens to concrete after 28 days?

After 28 days, concrete continues to harden and gain strength, although at a slower pace. This hardening process can technically go on for years, even decades, depending on environmental conditions and the specific concrete mix. 

Read more: We explain different methods to measure concrete maturity and how sensors improve measuring concrete maturity.

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