The construction industry is under increasing pressure to deliver faster, safer, and more sustainable projects. A critical challenge lies in accurately determining the in-situ strength of concrete to enable timely decision-making, such as form removal and post-tensioning. Traditional field-curing methods often introduce significant risk and uncertainty, especially with innovative, lower embodied carbon concrete mixes.

Wiss, Janney, Elstner Associates, Inc. (WJE Labs), a leading engineering and architectural firm specializing in materials evaluation and testing, has transitioned from traditional methods to fully embrace EXACT Match (EM2, EM3 units) across multiple critical projects. This technology has become the new gold standard for their work in materials evaluation and forensic analysis. The core application is the accurate, real-time concrete strength determination required for critical construction milestones, leading to a dramatic reduction in project risk, expedited construction schedules (saving days), and increased confidence in sustainable concrete mixes.

What is EXACT Match Technology?

EXACT Match Technology is a precision concrete curing and monitoring system that replicates the actual temperature profile of concrete placed in the field, within a controlled laboratory environment. This process, known as match curing, allows for the most accurate and reliable determination of concrete strength.

What EXACT Match Does:

1. Field Temperature Acquisition: Wireless temperature sensors (Probes) are embedded in the in-situ concrete element (e.g., slab, column, core wall) to capture its thermal history in real-time.
2. Thermal Profile Replication: The collected real-time field data is transmitted wirelessly to an EXACT Match chamber (such as the EM2 or EM3). This chamber precisely controls the temperature of companion concrete test cylinders, causing them to cure at the exact same thermal profile as the in-situ concrete.
3. Accurate Strength Testing: Because the cylinders have cured identically to the concrete in the structure, the compressive (or flexural) strength test results obtained from breaking these match-cured cylinders are an extremely accurate representation of the strength of the actual structure at that exact moment.
4. Remote Monitoring: Data is accessible remotely via your phone/laptop, allowing engineers and project teams to monitor the curing process and strength gain from anywhere.

The Critical Importance of Match Curing

The immense value WJE Labs gains stems from solving the fundamental problem of inaccurate concrete testing.

The Problem with Traditional Methods: Inaccurate Data and Durability Risk

As UofT Civil Engineering Professor Emeritus Doug Hooton, a leading expert in concrete durability, explains, “The heat accelerates strength gain, contractors often leave the cylinders next to structures overnight, but that’s not correct.” Traditional methods, like placing companion cylinders outside or under a tarp (“Fred Flintstone style,” as Professor Hooton puts it), fail to replicate the concrete’s actual temperature, leading to non-representative strength data.

WJE’s experts emphasized that relying on inconsistent temperatures poses both immediate and long-term risks:

• Schedule Delays: Documented delays in tilt-up operations because field-cured data did not provide teams with the confidence to make timely critical decisions.

• The Match Curing Solution: Scientific Precision

Match Curing accurately predicts what’s going on in the structure by replicating its exact thermal history.

Todd Nelson, WJE Labs: “Time is money. We need to accurately match the field temperature profile in the laboratory for our batch concrete, especially for very early age strength needs as quick as 4 hours required for big jobs.”

• Precision: Professor Hooton confirms, “EXACT uses surface temp at 25mm below the surface. That represents 95% of the concrete.” This critical difference delivers strength data days sooner than site or lab-cured cylinder strengths..
• Inconsistent Mixes: WJE conducted a rigorous side-by-side study with maturity sensors, field-cure, and match-cure methods. They found that maturity isn’t always reliable due to inconsistencies and variations in mix designs.

The System in Use

WJE Labs was led to the EXACT Match system by the need for a solution that provided unparalleled precision and could handle the complexities of modern mix designs:

1. Resolution and Accuracy: Their first concern was the ability of the system to closely match the thermal profile. WJE was impressed, noting: “The resolution of the equipment is really good. How closely you can match is amazing.”
2. Mix Design Evaluation: WJE uses the EM2 and two EM3 units primarily for the evaluation of concrete mix designs, especially those with lower embodied carbon.
3. Wireless and Remote Functionality: WJE required reliable equipment for field use. The ability of the unit to connect wirelessly was a major advantage, allowing an engineer to “log in from your home using their phone and see the graph from anywhere,” a feature not easily available with competing sensor systems.

Precision Power: Unmatched Profile Matching

WJE’s side-by-side comparisons of multiple methods showed a clear winner: The EXACT Match system’s ability to precisely replicate the field thermal profile was deemed far superior to their older, larger, more expensive environmental chambers.

Tom Van Dam, WJE Labs: “EXACT’s match curing is really the gold standard… We don’t know another product like this, there is nothing comparable out there.”

Risk-Reduction and Schedule Acceleration

For WJE Labs, EXACT Match is a risk-reduction mechanism and a schedule accelerator that directly addresses the challenges of using innovative, sustainable materials.

Measurable Benefits and Project Outcomes

WJE Labs found that the EXACT Match system delivers critical, measurable advantages that translate directly into reduced risk and accelerated schedules:

• Risk Reduction: The system enables owners, especially “hyper-scalers,” to confidently use the lowest embodied carbon mixes by providing verifiable, high-quality strength data. This confidence is crucial as it makes high-risk scenarios, such as low-temperature concrete placements, reliable.
• Schedule Ease: WJE realized a minimum 3 days of schedule ease on various projects. This acceleration enables faster progression to the next phase of work, including critical activities like form removal, post-tensioning, tilting up, and paving.
• Data Consistency: EXACT Match provides the highest percentage of reliability in scientifically accurate strength data, which is essential for project defense. It unifies and demonstrates the significant difference between accurate match-cure data and inconsistent field-cure or maturity data.

Trustworthy Data and Client Communication

The precision of the data acquired through match curing dramatically boosts the defensibility of WJE’s reports in high-stakes investigations.

WJE’s data provides the evidence that clients and owners need to trust and embrace new, sustainable concrete mixtures. This capability directly supports industry efforts to reduce embodied carbon, as promoted by initiatives like the Open Compute Project Foundation that WJE is partnering with to trial green concrete.

Standout Feature

The ability of the EM units to closely match the thermal profile in a controlled lab environment is the single greatest functional impact on WJE’s work. It delivers the true in-situ strength (compressive or flexural) with the necessary resolution.

Ready to establish the gold standard on your next project? Contact EXACT Technology today.