Technical Guide

Concrete Thermal Control Plan — What It Must Contain and How to Verify It

A concrete thermal control plan is the project document that sets out how peak temperature and temperature differential will be predicted, controlled, and monitored for a mass concrete or thermally sensitive pour — before, during, and after casting. It combines a pre-pour thermal prediction, the mitigation measures chosen to keep the pour within specified limits, and the monitoring and verification records needed to demonstrate compliance.

CIRIA C766Mass ConcreteQA DocumentationPre-pour Simulation
What it is

Why mass concrete pours require a thermal control plan

Large structural pours — pile caps, raft foundations, transfer slabs, and thick retaining walls — generate significant internal heat during cement hydration. Project specifications for these elements typically require a thermal control plan as a submittal before casting: a document showing the engineer has predicted the thermal behaviour of the pour, selected control measures to keep it within limits, and defined how compliance will be verified once concrete is placed.

A thermal control plan is distinct from a general thermal crack assessment. Where an assessment explains why cracking occurs and which elements are at risk (see thermal cracking in concrete), a thermal control plan is the project-specific deliverable — reviewed and approved by the consultant or resident engineer — that documents the predicted profile, the chosen mitigation measures, and the monitoring regime for a named pour or pour sequence.

Required contents

What a thermal control plan submittal typically includes

Pre-pour thermal prediction
Predicted peak core temperature, core-to-surface differential, and the temperature-time profile, generated from the mix design, element geometry, placing temperature, formwork, insulation, and pour sequence.
Control measures
The specific mitigation selected for the pour — GGBS or fly ash replacement level, placing temperature target, insulation or formwork retention period, pour sequencing or lift depth — and why it brings the pour within limits.
Acceptance criteria
The project-specific limits the pour must satisfy — commonly a peak temperature limit and a core-to-surface differential limit. These are set by the project specification and design basis, not by a single universal figure, and should be stated explicitly in the plan.
Monitoring and verification method
Sensor type and placement (core, mid-depth, surface), monitoring duration, reporting frequency, and the escalation procedure if readings approach or exceed the acceptance criteria during the pour.
Setting the limits

Temperature differential limits are project-specific, not universal

A common reference point in industry practice is a core-to-surface differential limit in the region of 20°C, intended to keep tensile strain at the surface within the concrete's early-age tensile capacity. But this figure is not a fixed regulatory value — the actual allowable differential depends on element geometry, mix design, degree of restraint, and the specific project specification. A thermal control plan should state the limit that applies to the pour in question, referenced to the project specification, rather than assume a generic industry number applies.

Peak temperature limits follow the same logic: many project specifications cap peak core temperature in the 65–75°C range to limit the risk of delayed ettringite formation and reduce long-term durability risk, but the applicable figure should always be confirmed against the specific project's design basis and specification.

CIRIA C766 Control of Cracking in Concrete Structures (2018) provides the assessment framework used to derive appropriate limits for a given geometry and restraint condition, and is the primary reference for thermal crack control in the UK and Commonwealth markets, including Singapore, Malaysia, and Australia.

Typical reference figures

Core-to-surface differential: often referenced around 20°C — confirm against project specification

Peak core temperature: commonly 65–75°C — confirm against project specification

No single figure governs universally. Always verify against the design basis and specification for the specific pour.

ConcreteAI's approach

From predicted profile to a documented, verified thermal control plan

ConcreteAI's Thermal Crack Management solution supports the full thermal control plan workflow — Simulate, Assess, Verify, Document:

Simulate and assess: Pre-pour simulation predicts peak temperature, core-to-surface differential, and crack risk from the actual mix design and geometry, letting the engineer select and justify control measures before the plan is submitted.

Verify: During the pour, embedded SmartHub sensors log core, mid-depth, and surface temperature continuously, so the actual profile can be compared against the plan's predicted profile and acceptance criteria in real time. If readings approach the specified limits, the site team is alerted via the web dashboard and WhatsApp before the criteria are exceeded.

Document:Continuous differential and temperature readings are compiled into a report against the plan's stated acceptance criteria — timestamped and project-tagged, ready for submission to the resident engineer or consultant. This replaces manual wired loggers, which typically take around an hour per point to install, have battery lives of 7–10 days, and require repeat site visits to retrieve data.

For the underlying mechanism of thermal cracking and which element types carry the highest risk, see thermal cracking in concrete — causes, assessment, and prevention. For continuous temperature and differential monitoring without a full thermal crack simulation, see mass concrete temperature monitoring.

Preparing a thermal control plan

Need a pre-pour thermal prediction for a mass concrete submittal?

ConcreteAI's engineering team can run a project-specific thermal simulation and help define the acceptance criteria and monitoring plan for your pour.

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FAQ

Frequently asked questions

A concrete thermal control plan is the project document that sets out how peak temperature and temperature differential will be predicted, controlled, and monitored for a mass concrete or thermally sensitive pour. It typically includes a pre-pour thermal prediction (peak core temperature, core-to-surface differential, temperature-time profile), the control measures selected to keep the pour within limits, the project-specific acceptance criteria, and the monitoring and verification method used during and after casting.
A typical submittal includes: a pre-pour thermal prediction generated from the mix design, geometry, placing temperature, formwork, and pour sequence; the specific control measures chosen (SCM replacement level, placing temperature target, insulation or formwork retention, pour sequencing); the project-specific acceptance criteria for peak temperature and differential; and the monitoring method — sensor placement, reporting frequency, and the escalation procedure if readings approach the specified limits.
There is no single universal limit. A core-to-surface differential in the region of 20°C is a common reference point in industry practice, but the applicable limit depends on element geometry, mix design, degree of restraint, and the project specification. CIRIA C766 provides the assessment framework used to derive an appropriate limit for a given geometry and restraint condition. The plan should always state the specific limit confirmed against the project's design basis and specification, not a generic figure.
Verification compares actual monitored temperatures against the plan's predicted profile and stated acceptance criteria. Continuous monitoring at core, mid-depth, and surface positions — typically via embedded sensors — allows the actual peak temperature and differential to be tracked against the plan in real time, with alerts if readings approach the specified limits. The resulting data is compiled into a report for submission to the resident engineer or consultant as evidence the pour was controlled within the plan.
A thermal crack assessment explains the mechanism of thermal cracking and identifies which element types and mix designs carry the highest risk in general terms. A thermal control plan is the project-specific deliverable for a named pour or pour sequence — it documents the predicted profile, the chosen mitigation measures, the acceptance criteria, and the monitoring regime for that specific element, and is typically reviewed and approved by the consultant or resident engineer before casting proceeds.