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The measured or predicted temperature at the center of the mass concrete element, in °C.
Measured with an embedded thermocouple or temperature sensor, typically peaking a few days after placement due to cement hydration heat.
The measured or predicted temperature at the concrete surface, in °C.
The surface cools faster than the core because it's exposed to ambient air — a large gap between the two creates tensile stress that can crack the surface.
Core-to-surface temperature differential
30.6 Δ°F
The core-to-surface differential and the core temperature are both under ACI 301's limits — 35 °F (19.44 °C) and 160 °F (71.11 °C) — shown with them. Those are two of the thermal control limits and they are checked against the figures entered — the pour's own temperatures are what govern, and they are measured, not predicted here.
- ACI 301 gradient limit
- 35 Δ°F
- Core temperature
- 113 °F
- ACI 301 max core temperature
- 160 °F
They open the calculator with your figures already in it
Mass Concrete Thermal Gradient Calculator: 30.6 Δ°F — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- ACI 301 standard mass concrete thermal control limits: maximum core-to-surface temperature differential of 35°F (19.44°C), and maximum concrete temperature of 160°F (71.11°C) during curing
Inputs used
- Core Temperature
- 113 °F
- Surface Temperature
- 82.4 °F
Intermediate steps
- ACI 301 gradient limit
- 35 Δ°F
- Core temperature
- 113 °F
- ACI 301 max core temperature
- 160 °F
Confidence note: The core-to-surface differential and the core temperature are both under ACI 301's limits — 35 °F (19.44 °C) and 160 °F (71.11 °C) — shown with them. Those are two of the thermal control limits and they are checked against the figures entered — the pour's own temperatures are what govern, and they are measured, not predicted here.
What this calculation does not cover
- This checks two temperatures you already have; it does not predict either one. Mix design, cement content, SCM replacement, placement temperature, element thickness, formwork type, insulation R-value and ambient weather play no part in the arithmetic, so it cannot tell you what gradient a pour will develop — only whether the pair of numbers you enter sits inside the limit.
- The comparison is against ACI 301's default thermal control limits, not a project-specific one. A performance-based differential derived from your concrete's tensile strength, elastic modulus and coefficient of thermal expansion can be higher or lower than the default, and that calculation, along with the thermal control plan itself, belongs to the engineer of record. This page is a screening check, not a design or an acceptance record.
- One core reading against one surface reading represents the whole element. Corners, edges, the underside against a mud slab, restraint from adjoining pours and the local gradient after formwork strip all behave differently, and none of them appear here. The answer is also only as good as where the thermocouples sit and when you read them — a surface probe at the wrong depth or a reading taken before the core has peaked changes the differential without changing anything the calculator can see.
- Nothing about the rate of change is modelled. Two pours can show the same instantaneous differential while one is cooling far faster than the other, and cooling rate is a separate control on mass concrete that this snapshot does not represent.
- The surface temperature field will not go below 0 °C (32 °F) and the core field stops at 90 °C (194 °F); a value outside those is replaced with the bound and the result is then graded on the substitute. A sub-freezing surface reading during a cold-weather placement — the case where the gradient is worst — cannot be entered as measured, and the differential it reports will be smaller than the real one.
Add the equipment this sizes
This result is a specification — 30.6 Δ°F — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-05 · in the site-wide review of 2026-09-06 · v1.2.1
Regulatory standards & verification citations1
- ACI 301 standard mass concrete thermal control limits: maximum core-to-surface temperature differential of 35°F (19.44°C), and maximum concrete temperature of 160°F (71.11°C) during curing
Which documents these citations point at
Standards referenced: ACI 301 (American Concrete Institute, United States).
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