Strength you can act on, from a maturity function calibrated to the actual cement in your pour — not one generic curve stretched across all of them.
Input mix design and materials data. PROTEST calibrates the maturity model to your concrete.
Embed temperature sensors in the concrete at critical locations before the pour.
PROTEST continuously records temperature data and calculates maturity in real time.
PROTEST converts maturity to in-situ strength and benchmarks against project targets.
Clear reports and alerts support decisions on formwork, load, and programme.
Sensors cast into the pour report the concrete's temperature. PROTEST logs it every 10 minutes, continuously, building the actual thermal history as it cures.
A maturity function converts that temperature-time history into an equivalent age — using a temperature-sensitivity value derived for your cement class, not a CEM I default.
Maturity maps to in-situ compressive strength using a calibrated curve for your specific mix — a real MPa value, on demand.
Every maturity system calibrates a strength-versus-maturity curve from cubes cured at 20 °C. That part is standard and everybody does it. The second calibration is the maturity function itself — the relationship that converts a temperature history into maturity — and that is the one most systems leave on a CEM I default.
Under BS EN 13670:2009 the maturity function has to be justified against the cement actually in use, not against a widely used one. On most systems that proving is your job. PROTEST holds a function calibrated per cement class, so it is already done — real-time in-situ strength from the first pour.
Many systems default to Sadgrove or Nurse-Saul until you input your own maturity function calibration data.
Maturity monitoring beating cube schedules for early-age decisions is well established. The part most systems skip is the second calibration — matching the maturity function itself to the cement going into the pour, not just the strength curve to the mix.
| Standard-cured cubes | Generic maturity monitoring | PROTEST | |
|---|---|---|---|
| Reflects the real structure's temperature | No — cured in a 20 °C water bath, not the pour | Depends — only if the function's temperature sensitivity is calibrated to the mix | Yes — calibrated per cement class from the first pour |
| Result timing | Days later — lab break on a fixed schedule | Real time | Real time |
| Maturity function matched to your cement | N/A | CEM I default — usually left on Nurse-Saul or Sadgrove | Built in — per cement class, nothing to configure |
| Accuracy on GGBS / PFA mixes | N/A — measures the cube itself | Degrades — a CEM I-calibrated conversion doesn't track GGBS's different temperature sensitivity | Accurate — function matches the actual cementitious combination |
| Role under BS EN 13670 | Required — conformity record | Supports — early-age decisions, if properly calibrated | Supports — early-age decisions, calibration already proven |
| Non-destructive, continuous | No — one-off destructive break | Yes | Yes |
Cube testing remains the required conformity record under BS EN 13670 regardless of maturity monitoring — PROTEST supports the early-age decisions made ahead of that result, it doesn't replace it.
BS EN 13670:2009 doesn't accept a generic maturity function. The requirement is that it must be justified against the actual cement, or cement-and-addition combination, going into the pour — not a function that happens to be widely used. That's a higher bar than it first appears — because the maturity method is really two calibrations, not one.
Maps maturity to MPa. Calibrated from crushed specimens cured at one temperature. UK teams do this properly, mix by mix.
Converts temperature history into maturity. Usually Nurse-Saul or Sadgrove in the UK. Its temperature sensitivity should reflect the cementitious combination — but is typically left on a default, and with Sadgrove cannot be adjusted at all.
The first gets calibrated diligently. The second is usually left as it comes. On UK projects the function is typically Nurse-Saul or Sadgrove, and in practice neither is usually matched to the mix. Nurse-Saul is commonly left on a default datum temperature: 0 °C is the value ASTM C1074 recommends for Type I cement without admixtures, over a curing range of 0–40 °C. Sadgrove carries no parameter for adapting temperature sensitivity to different mixes at all.
Here's the practical effect. The strength curve is calibrated to your mix. The temperature conversion isn't — it still assumes CEM I. Lab cubes are cured at a standard 20 °C, so on a pour running close to 20 °C, that barely matters. But GGBS is significantly more temperature-sensitive than CEM I — slower-gaining in cold weather, but capable of accelerating hard in a hot mass core — and a CEM I-calibrated conversion doesn't track either direction correctly. Any site condition away from that 20 °C reference is where the mismatch grows — and those are exactly the pours where the strength data matters most.
Where the function does have a parameter, deriving the right value for a GGBS or PFA blend means the separate multi-temperature procedure in ASTM C1074 Appendix X1 — three water baths, mortar cubes, an exercise entirely separate from the crushing schedule. On most systems, that work is yours to do.
PROTEST holds maturity functions for each cement class. The strength relationship can also start from OTB's own strength predictions for your mix, refined as your team supplies calibration data while the job runs. The difference is you're verifying a live curve from the first pour, not waiting a month to build one.
What engineers and contract administrators ask before adopting maturity monitoring.
No, and any supplier who says otherwise is overselling it. Under BS EN 13670 the 28-day cube remains the conformity record that proves the mix meets its specified strength class. That requirement doesn't change.
What maturity monitoring replaces is the waiting. Striking, stressing and loading decisions are made days before a 28-day result exists, and they're currently made against a conservative schedule or an early cube break. Maturity gives you in-situ strength at the moment you need the decision, from the concrete in the structure rather than a cube in a tank.
The maturity method is really two calibrations, not one: a strength–maturity relationship for your mix, and a maturity function that converts temperature history into maturity. Almost everyone calibrates the first properly. The second is usually left on a default.
That default is effectively CEM I-biased. PROTEST holds a maturity function calibrated for each cement class, so the conversion matches the cementitious combination actually going into the pour — which is what BS EN 13670 asks for, and what makes the strength figure trustworthy on a GGBS or PFA mix.
Because GGBS is significantly more temperature-sensitive than CEM I — slower-gaining in cold weather, but capable of accelerating hard in a hot mass core. A conversion calibrated on CEM I doesn't track either direction correctly.
Lab cubes are cured at a standard 20 °C, so on a pour sitting close to 20 °C the mismatch barely shows. It grows with every degree away from that reference — which means the error is largest on exactly the pours where the strength data matters most.
The maturity function is already calibrated per cement class, so there's no multi-temperature procedure for your team to run. The strength relationship can start from OTB's own strength predictions for your mix and be refined as your calibration data comes in during the job.
The practical difference is that you're verifying a live curve from the first pour rather than waiting a month to build one before the system is useful.
Yes. BS EN 13670 recognises the maturity method for demonstrating in-situ strength. The condition is that the maturity function must be justified against the actual cement, or cement-and-addition combination, going into the pour — not simply a function that happens to be widely used.
That's a higher bar than it first appears, and it's the specific requirement most systems leave to the customer to satisfy.
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