A NC2 MAP Brief, “Maturity Method for Early Opening of Concrete Pavements,” offers a detailed summary for construction professionals on a technique that could significantly reduce project timelines and costs. Authored by ISCP Treasurer Armen Amirkhanian from The University of Alabama, the brief highlights the concrete maturity method as a reliable way to assess the in-place strength of concrete pavements in their early stages. This innovative approach considers both curing time and temperature, providing a more accurate strength estimate than traditional methods that rely on laboratory specimens. The project was sponsored by the Technology Transfer Concrete Consortium, TPF-5(437), and is part of a larger effort to enhance transportation infrastructure.
The maturity method is based on a concept that originated in England in the 1940s and 1950s. Researchers discovered that two identical concrete mixtures would achieve similar strengths if they reached the same “maturity level,” which is a cumulative measure of the combined effects of time and temperature. This idea was formalized as the “maturity rule” and later standardized in the United States as the Nurse-Saul method, codified in ASTM C1074. This method is particularly relevant for determining when to open new pavements to traffic, a critical factor for minimizing construction delays. The recent project focuses on the maturity method as outlined in the AASHTO T 413 standard, a key development for the industry.
The core principle behind the Nurse-Saul method is that concrete strength gain is directly related to the area under a temperature-time curve. For example, if a pavement is poured on a warm day, it may reach the required opening strength in 33 hours. If the same mix is poured on a cooler day, it may take 39 hours to achieve that same strength because the cement hydration process is slower. By continuously monitoring the concrete’s temperature with embedded sensors, practitioners can calculate the temperature-time factor (TTF) and use it to estimate the in-place strength. This allows for informed, real-time decisions about when a pavement can safely handle traffic.
Implementing this method requires a clear, step-by-step process. First, a unique maturity-strength relationship must be established for the specific concrete mix through laboratory testing. Once this calibration curve is developed, temperature sensors are placed within the new pavement during construction to monitor its curing. The data from these sensors are used to calculate the pavement’s maturity, and by comparing this value to the pre-established curve, the current strength can be estimated. The pavement is then opened to traffic once it reaches the required strength criteria. This entire process is far more dynamic and responsive to real-world conditions than simply waiting for a predetermined amount of time to pass.
The maturity method has a proven track record of successful implementation, with state departments of transportation, such as the Iowa DOT, using it for over two decades. Projects have consistently shown that the method leads to earlier pavement openings, resulting in significant time and cost savings. While the maturity method offers substantial benefits, its successful use requires careful attention to detail. Practitioners must properly calibrate the maturity curve for each mix, ensure correct sensor placement, and perform periodic curve validations as outlined in AASHTO T 413. Providing adequate training for personnel is also crucial to ensure the method is applied correctly and effectively, maximizing its potential for more efficient and timely project completion.
Read the full report here: https://www.intrans.iastate.edu/wp-content/uploads/2025/04/maturity_method_for_concrete_pvmt_early_opening_spring_2025_MB.pdf