accessible_forward
Accessibility Statement. Read more.
This eBook covers a brief history of Concrete Maturity and what has become known as the Maturity Method, including key benefits of using this method.
Concrete is the most versatile and widely used construction material in the world. One of the very few downsides to using concrete in construction is predicting the time needed to reach design strength so the project can move forward.
The Concrete Maturity Method is a non-destructive testing method used to estimate the early-age strength development of in-situ concrete. Based on the principle that concrete strength is directly related to its hydration temperature history, the Maturity Method is a simple approach for estimating the compressive strength of concrete, especially at early ages (less than 14 days).
Despite concrete being used for millennia, the understanding and application of concrete Maturity Methods were limited and not widely adopted in construction practices before the 1970s.
Thanks to innovative new technologies — like embedded sensors, data loggers, AI, and analytics platforms — the concrete Maturity Method offers real-time strength data and accurate estimations of strength.
Since contractors, architects, and engineers are always looking for ways to speed up construction to reduce schedules and drive profitability, the modern Concrete Maturity Method is designed for predicting concrete strength — especially when concrete is on the critical path of construction.
The Method offers a predictive model for assessing concrete strength accurately and efficiently. However, despite its proven advantages — including significant time and cost savings as well as safety and sustainability benefits — its adoption faces hurdles due to misconceptions and a lack of understanding among key construction stakeholders.
This guide aims to clarify the principles, applications, and new innovations in the concrete Maturity Method — using concrete sensors and advanced analytics — to deliver cost savings and efficiency gains, and even support sustainability goals.
Concrete maturity is a measure that provides insight into the progression of concrete curing and strength development, predicated on the concrete’s temperature history over time. This concept hinges on the understanding that concrete’s strength gain is not just a function of time but is significantly influenced by the curing temperature. High temperatures accelerate the chemical reactions in concrete, thus speeding up strength development, whereas low temperatures slow these reactions.
The maturity of concrete is calculated using specific formulas that integrate the effect of temperature over time. Two primary models are used:
Both models require continuous monitoring of concrete temperatures, from which a maturity index can be derived. A maturity index (calculated in Celsius hours) predicts concrete strength based on a pre-established correlation between maturity and strength for the specific concrete mix used.
The terms “maturity” and “strength” are not interchangeable, but there is a relationship between maturity and strength of a concrete mix.
The strength of concrete and other related properties are directly proportional to the age and temperature variations of the concrete structure.
Initially, the construction industry relied on empirical methods to estimate concrete strength, the most common of which is the manual cylinder testing method where contractors would take two sets of samples — known as cylinders — when concrete is poured. The first set is cured under standard curing conditions in a lab, and the second set is left to cure on the job site. At various times, a field-cured sample is sent to a lab for strength testing. This is repeated until the desired strength is reached. This manual testing process has several limitations:
These limitations have prompted the construction industry to seek accurate, efficient, and sustainable methods for assessing concrete strength in the field. The adoption of the Concrete Maturity Method — using embedded sensors, data loggers, and analytics platforms — represents a significant advancement in overcoming these challenges, offering real-time, continuous monitoring of concrete strength development without the drawbacks of manual cylinder testing.
As we explore the Concrete Maturity Method, it’s important to recognize the regulatory
landscape that governs its application. Today, various codes and standards exist for maturity testing, which vary regionally and are subject to regular updates. Adhering to these standards ensures that construction practices are aligned with the latest industry norms and regulatory requirements.
CANADA
UNITED STATES
The Concrete Maturity Method leverages technology from simple thermocouples to IoT, wireless and wired sensors, AI, and analytics technologies to accurately predict the compressive strength of concrete.
The Maturity Method is governed by the basic assumption that a concrete mix design poured on a project has the same compressive strength at its maturity index. In other words, a concrete mix may reach the same compressive strength after 15 hours of curing at 20ºC as when it is cured for 10 hours at 30ºC. That’s because when the concrete cures, it creates heat from cement hydration, which gets trapped inside the concrete. The high temperature helps the concrete cure faster.
The Maturity Method requires pre-calibration of a concrete mix before it can be used to correlate the concrete maturity to its strength.
The aim of performing a maturity calibration is to find the relationship between time, temperature, and strength for each concrete mix design that you intend to use.
Implementing the Maturity Method starts with the calibration process to establish a relationship between maturity and concrete strength for the specific mix design in question.
This involves casting concrete samples under controlled conditions, monitoring their temperature history, and testing their strength at various ages. The results produce a maturity curve that serves as a reference for field applications.
Calibration is a critical step that involves testing several concrete specimens at different curing times to develop a correlation curve between the concrete’s maturity index and its compressive strength. This curve is unique to each concrete mix and is used to predict the in-situ concrete strength accurately.
Sensors play a pivotal role in the Maturity Method of testing, continuously recording the temperature of in-situ concrete.
The choice of sensors (wired vs. wireless), their placement within the concrete structure, and the frequency of data collection are crucial considerations for accurate maturity assessment.
The implementation of the Maturity Method of testing in construction projects requires coordination between project managers, engineers, and field technicians. Ensuring that the calibration curve is accurately developed and applied, that sensors are correctly installed and functioning, and that data is continuously monitored and interpreted, are all key to leveraging the full benefits of the Maturity Method for concrete strength estimation.
CYLINDER VS. MATURITY METHOD
Since the modern Maturity Method uses the temperature variation within the concrete, it can accurately predict its in-situ strength in real time. In comparison, cylinder testing has a much smaller mass and a larger surface area, which means the heat within the cylinder dissipates faster, slowing down the strength gain compared to in-situ concrete.
Maturity testing sensors may be either wired or wireless (embedded).
The choice between wired and wireless sensors will depend on the project’s specific needs, including scale, complexity, and environmental factors
Sensors should be strategically placed at representative locations within the concrete structure to capture temperature profiles that accurately reflect the curing conditions.
Modern maturity systems offer real-time monitoring capabilities, enabling instant access to temperature and calculated maturity data.
This technology facilitates timely decisions regarding formwork removal, post tensioning, or opening pavements to traffic.
Maturity sensors may be wired or embedded. The choice will depend on the project’s specific needs, including scale, complexity, and environmental factors.
Wired sensors are embedded within the concrete, at various depths and locations, depending on the project requirements, with wires extending to a central data logger, ensuring continuous and accurate monitoring of temperature changes crucial for calculating the maturity index.
The primary advantage of wired sensors is their proven reliability and accuracy. They offer continuous, direct monitoring of concrete’s temperature, which is crucial for accurately calculating maturity indexes.
Traditional thermocouple systems are connected to data loggers that store temperature readings for subsequent analysis. While these systems provide precise historical temperature data, they typically do not offer real-time data access.
This makes them suitable for projects where post-curing analysis of temperature and maturity data is sufficient.
Innovations in wired sensor technology have led to systems that combine the reliability and accuracy of wired connections with the convenience of real-time data transmission. The Helix® system demonstrates this, featuring reusable external nodes that wirelessly transmit data to the cloud. By leveraging wireless IoT technology, these systems offer the best of both worlds — the precision of wired sensors with the immediacy of wireless data access.
Despite their benefits, the use of wired sensors requires careful operational planning, especially in large-scale or complex concrete pours. Managing the wires and ensuring their integrity throughout the curing process can present logistical challenges. Some key considerations include:
Despite these challenges, wired sensors are highly valued for projects where stable, uninterrupted data collection is paramount. They are particularly suited to environments where wireless communication might be unreliable or where the additional precision of a wired connection is required.
Embedded sensors offer a seamless, non-intrusive way to monitor the curing process from within the concrete itself. These sensors are attached to the rebar before a pour and remain in place throughout the lifespan of the structure. They measure temperature and other relevant data, transmitting this information wirelessly to a receiver or directly to a cloud-based platform.
The advantage of embedded sensors is their ability to provide real-time, comprehensive data without the need for external wires or manual data retrieval. This wireless transmission eliminates many logistical hurdles associated with wired sensors, making the setup quicker and reducing the risk of data loss or damage to physical connections.
Embedded sensors are particularly beneficial for monitoring critical structural elements where understanding internal conditions is essential for assessing overall concrete maturity and strength.
Embedded sensors streamline the process of concrete monitoring, allowing for more dynamic and responsive project management. By delivering accurate, real-time insights directly to stakeholders, these sensors empower teams to make informed decisions faster, optimizing construction schedules and enhancing the safety and durability of the finished structure.
The transition to the Maturity Method from traditional testing techniques is not just a technical upgrade but a strategic business decision. By harnessing the predictive power of the Maturity Method, contractors can achieve remarkable cost savings, efficiency improvements, and sustainability benefits.
Implementing the Maturity Method of testing helps you move the project forward and strike formwork as soon as possible.
By reducing the need for numerous samples and laboratory tests, project costs are also directly cut. Additionally, the method’s accuracy minimizes the risk of rework due to premature load applications, further saving resources and expenses.
Using the Maturity Method on construction projects has clear economic benefits. Not only can large projects save money—but smaller ones can too.
The Maturity Method can save a lot of time by making essential tasks like removing formwork, post-tensioning, and opening roads to traffic much faster and more efficiently. And in the construction business, saving time means saving money.
Starting to use the Maturity Method does have some upfront costs, like buying and calibrating the maturity sensors. But the real value comes from the money it saves in the long run.
The landscape of concrete maturity testing is still evolving today. Innovations such as wireless sensor networks, Internet of Things (IoT) connectivity, and cloud computing are making real time data collection and analysis accessible. These technologies facilitate a seamless flow of information, enabling construction teams to make informed decisions swiftly, based on the latest concrete strength data.
Artificial Intelligence (AI) and machine learning are set to play a pivotal role in the future of concrete maturity testing. These technologies can analyze vast amounts of data collected from sensors embedded in concrete, identifying patterns and correlations that may not be apparent through traditional analysis methods. By learning from historical data, AI models can predict concrete strength with high accuracy, potentially eliminating the need for physical testing.
ConcreteDNA is a powerful technology that combines some of the most cutting-edge technologies with robust sensors to deliver AI-powered concrete monitoring, data management, and mix selection capabilities. It helps busy contractors make informed decisions quickly, optimize labor and resources, and accelerate project timelines.
Wireless, embedded sensors monitor concrete temperature and strength in real-time and send data to the cloud so you can access it from almost any device.
Real-time concrete strength and temperature monitoring for faster concrete construction.
Predictive concrete analytics to assist with mix selection and help you build fast and efficiently.
Advanced Maturity Methods are also expected to contribute significantly to sustainability and efficiency in construction. By providing accurate strength predictions, these methods can help optimize the use of materials and reduce waste.
For example, knowing the exact point at which concrete reaches sufficient strength could minimize the overuse of cement, a major source of embodied carbon emissions in construction.
Additionally, the ability to accurately predict concrete strength in real time allows for more efficient project scheduling and resource allocation. This can lead to shorter construction times, reduced labor costs, and lower overall environmental impact.
The data collected through the Maturity Method can also be used to optimize concrete mix designs.
Converge, a DEWALT Product
DEWALT Concrete Sensors are a line of wireless sensors designed to monitor concrete's temperature during the curing process. These sensors are used in construction projects to ensure that concrete is cured properly, which can help prevent cracking and other problems that can compromise the structure's integrity.