Concrete
Mass concrete thermal control and cracking field guide
What makes a placement mass concrete, the two temperature limits that govern it, and how the crew holds them with the mix, precooling, insulation, and monitoring.
Direct answer
Mass concrete is any placement thick enough that the heat from cement hydration builds in the core faster than it escapes at the surface. Two limits control it: a maximum core temperature, commonly 158F, and a maximum core-to-surface difference, commonly 35F. A thermal control plan accepted by the engineer governs the placement.
Key takeaways
- Mass concrete is governed by two limits: a maximum core temperature, commonly 158F (70C), and a maximum core-to-surface difference, commonly 35F (19.4C).
- A least dimension of about 3 to 4 ft is the common rule for mass concrete, but heat of hydration decides, not size alone.
- The 158F core cap prevents delayed ettringite formation (DEF); the 35F differential prevents thermal cracking of the cooler surface.
- Insulate the surface and leave forms on to hold the differential; cooling the surface widens the core-to-surface gap and drives cracking.
- A thermal control plan, required by ACI 301 and accepted by the engineer of record, governs every mass placement; ACI 207 is the reference.
What mass concrete is, and why the heat is the problem
Mass concrete is any placement large enough that the heat released as the cement hydrates builds up in the core faster than it can escape at the surface. The center heats. The outside cools to the air. That split is the whole problem, because the warm core wants to expand while the cooler skin holds it back, and the skin goes into tension it was never meant to carry. When the tension beats the early tensile strength, it cracks.
Size is the trigger but heat is the cause. A data center foundation mat, a deep pile cap, a transformer or generator pad, a bridge pier, a thick footing under a heavy column, any of them can hold heat in the middle for days. The bigger the element, the longer the core stays hot and the steeper the difference to the surface. A 6 in slab sheds its heat almost as fast as it makes it. A 6 ft mat does not.
This guide is about holding two numbers: how hot the core gets, and how far the core runs ahead of the surface. Everything else, the mix, the placing temperature, the cooling, the insulation, the monitoring, exists to keep those two numbers inside the limits the engineer set. The approved mix design is the starting point, and a separate guide on mix design and the water-cement ratio covers how the supplier proportions it. Here the concern is the heat that mix makes once it is in a big form.
When does concrete become mass concrete?
There is no single thickness that flips a placement into mass concrete, but the rule of thumb most crews carry is a least dimension of about 3 to 4 ft. ACI 207, the guide to mass concrete, defines it by behavior rather than size: any volume of concrete with dimensions large enough to require measures to deal with the heat of hydration and the volume change that follows, so cracking is controlled. The least dimension is the smallest of the three, because that is the shortest path heat has to travel to get out.
So a 3 ft thick mat is mass concrete even if it is only 8 ft square. The 3 ft dimension is what traps the heat. A 2 ft wall can behave like mass concrete too if the mix is rich, the cement content high, and the weather warm, because the heat decides, not the tape measure. That is the trap. Crews look at a footing that is not especially big and assume the thermal rules do not apply, then it cracks.
When the spec calls a placement mass concrete, it says so in the contract documents and the thermal requirements come with it. When it does not and the element is borderline, raise it before the pour. The cheapest time to ask whether something is mass concrete is when the mix is still being submitted.
The heat of hydration
Cement and water react exothermically. The reaction that turns the paste hard also gives off heat, and in a thin section that heat leaves about as fast as it arrives, so the concrete barely warms. Pack the same reaction into a thick section and the heat has nowhere to go. It accumulates, and the core temperature climbs well above the temperature the concrete was placed at.
The rise is not instant. The peak usually lands a day to a few days after placement, depending on the mix, the placing temperature, and the size of the element. A big mat placed warm can run 50 to 80F above its placing temperature at the core before it turns the corner and starts to cool. Place it at 75F and the core can sit above 150F at the peak with nothing done to stop it.
How much heat, and how fast, is mostly set by the cement: how much of it is in the mix and what type. More cement means more heat. Finer, higher early-strength cement means faster heat. That is why the levers for controlling the peak start with the mix, and why a mix that is fine for a slab can be wrong for a mat.
What is the maximum temperature for mass concrete?
Two limits govern a mass placement, and they pull in different directions. The first is a maximum core temperature, commonly held at 158F (70C), set to avoid delayed ettringite formation. The second is a maximum difference between the core and the surface, commonly held at 35F (19.4C), set to avoid thermal cracking. A placement has to satisfy both at the same time.
These numbers come from ACI 301 and the project specification. The 158F maximum protects the concrete chemistry. When supplementary cementitious materials are used, the spec sometimes allows a higher cap, up into the 160s or 170s F and occasionally to 185F (85C), because the SCMs change the risk. The 35F differential protects the concrete from cracking itself apart as the core and surface change temperature at different rates.
Treat both as numbers the engineer of record owns. The 158F and 35F figures are common spec values, not laws of physics, and the engineer can set them tighter or, with justification, looser. The differential limit in particular is sometimes raised for confined or permanently cased elements. Confirm the actual limits in the project documents before the pour, because they drive every other decision in the plan.
| Limit | Common value | What it prevents |
|---|---|---|
| Max core temperature | 158F (70C) | Delayed ettringite formation (DEF) |
| Max core temp with SCMs | Often higher per spec, up to ~185F | DEF, with SCM risk reduction credited |
| Max core-to-surface difference | 35F (19.4C) | Thermal cracking |
| Governing authority | Project spec / engineer of record | Both numbers can be set tighter |
Delayed ettringite formation (DEF)
Delayed ettringite formation, DEF, is internal expansion and cracking that shows up months to years after a placement, and it traces back to the core getting too hot while the concrete was young. Above roughly 158 to 160F, ettringite, one of the early hydration products, is no longer stable and does not form normally. The sulfate that would have gone into it stays held in the paste.
Later, with the concrete hardened and moisture present, the ettringite forms after all, in a matrix that has no room for it. The crystals grow, they push, and the paste expands and cracks from the inside. There is no fixing it once it is in. You cannot pour out the heat that was already in the core last year.
This is why the maximum core temperature exists, and why it is a chemistry limit, not a cracking limit. A placement can show no surface cracks at all, pass every early test, and still be carrying a DEF problem because the core ran hot for a day during the peak. The only defense is keeping the core under the cap in the first place, which is the whole reason to know the peak before it happens, not after.
How the differential cracks the concrete
Thermal cracking is the differential problem, and it is mechanical, not chemical. While the core is hot and expanded and the surface is cooler, the surface is stretched over the larger core and pulled into tension. Young concrete has very little tensile strength. When the surface tension beats that strength, it cracks, and the cracks can run deep.
The difference, not the absolute temperature, drives this. A core at 150F next to a surface at 145F is fine. A core at 150F next to a surface at 100F is a 50F difference and a cracking risk, even though the core is under the 158F cap. That is the counterintuitive part for crews used to thinking hot is the only enemy. A cold surface on a hot core is exactly the condition you are trying to avoid.
There is a second act. As the core finally cools, it contracts, and if it is restrained by the foundation, by older concrete, or by its own cooled outer shell, that contraction can crack it too. The first cracking risk is the heat-up differential. The later one is the restrained cooldown. A good plan addresses both, which is why the cooldown is managed and not just left to happen.
What is a thermal control plan?
A thermal control plan is the engineered document that says how a specific mass placement will stay inside the temperature limits. It is required by ACI 301 and by most specs for any placement designated mass concrete, and it is normally prepared by or for the contractor and submitted to the engineer of record, who reviews and accepts it. The contractor owns the means and methods. The engineer owns the limits and the acceptance.
A real plan covers the mix and its predicted heat, the maximum placing temperature, the predicted peak core temperature and peak differential from a thermal model, the cooling and insulation measures, the monitoring scheme with sensor locations, the action thresholds, and the controlled cooldown with when protection can come off. The model ties it together, because it predicts whether the chosen measures actually hold the two limits before a single yard is placed.
Skipping the plan is the first failure. A mass placement run without one is a placement where nobody predicted the peak, nobody set the action thresholds, and nobody decided when it was safe to strip. By the time the core temperature is climbing past the cap, it is too late to do anything but watch. The plan is cheap. The mat is not.
The mix that makes less heat
The mix is the first and biggest lever on the heat, because the heat comes from the cement. Three moves reduce it, and they stack. Use a lower-heat cement, ASTM Type II for moderate heat or Type IV for low heat where it is available. Replace a large fraction of the portland cement with supplementary cementitious materials, fly ash or ground granulated blast furnace slag, which react slower and give off less heat. And keep the total cementitious content no higher than the strength and durability actually require.
The SCM replacement is the workhorse on modern mass placements. Class F fly ash and slag both cut the peak temperature and slow the heat down so it spreads over more time, which lowers the peak the core ever reaches. Replacement levels on mass concrete run high, sometimes 50 percent or more of the cementitious material, and slag in particular is used at very high levels on big pours. The supplier proportions all of this. The mix design and water-cement ratio guide on this site covers how that proportioning is done and who owns it.
There is a tradeoff to respect. High SCM mixes gain strength slower at early age, so the schedule for form stripping and loading has to account for it. They also change the DEF risk picture, which is why a spec sometimes allows a higher temperature cap when SCMs are used. None of this is a field decision. It is set in the approved mix and the thermal control plan, and the crew's job is to place what was approved.
How do you lower the placing temperature?
You lower the placing temperature by cooling the ingredients before they ever reach the forms, and it pays back directly: roughly every degree you take off the fresh concrete comes off the peak core temperature too. Start the concrete cold and it peaks lower, with more margin under the 158F cap. The methods, from least to most aggressive, are chilling the mix water, replacing part of the mix water with ice, cooling the aggregate, and injecting liquid nitrogen.
Ice is the common workhorse. Replacing a portion of the mix water with flake or crushed ice cools the batch far more than chilled water alone, because melting the ice absorbs a large amount of heat (the latent heat of fusion) without adding any water beyond what the mix already counts. The water-cement ratio is protected because the ice is part of the water, not on top of it. Chilled water alone helps but gives back less. Cooling the aggregate matters because aggregate is most of the mass.
Liquid nitrogen is the heavy tool. Injected into the mix, it boils off at very low temperature and pulls heat out fast, and it lets the batch operator hit a target placing temperature precisely without touching the water content. It costs more and needs the equipment on site, so it shows up on the big, temperature-critical placements. Night placement, when the ambient is lowest, is the free version of precooling and belongs in the plan whenever the schedule allows it.
Post-cooling and embedded cooling pipes
Post-cooling pulls heat out of the concrete after it is placed, using cooling pipes embedded in the concrete with water circulated through them. It is the dam-and-big-mat tool, described in ACI 207.4R, and the technique goes back to Hoover Dam in the 1930s, where cold water through embedded pipe coils cooled the monoliths so the contraction joints could be grouted.
The pipe coils are tied down on top of each hardened lift, so the vertical pipe spacing follows the lift height, and water is circulated to carry heat away while the core is hottest. Done right it holds the peak down and lets the core cool on a controlled schedule instead of on its own. Done wrong, with water too cold, it creates its own difference between the concrete near the pipe and the concrete between pipes, so the cooling water temperature and the flow are part of the design, not just turned on full.
Most building work never needs embedded pipes. Precooling, a low-heat mix, and surface insulation handle the great majority of mats and footings. Post-cooling enters when the element is so large that nothing else can keep the core under the cap, or when the schedule needs the controlled cooldown that only active cooling delivers. It is engineered, monitored, and shut down on a plan, not by feel.
Why insulate mass concrete instead of cooling the surface?
Because the enemy is the difference, not the heat, and cooling the surface makes the difference worse. The core is going to be hot no matter what for the first days. If you also let the surface get cold, by stripping forms early or hosing it down or leaving it bare in cold air, you widen the gap between core and surface and you drive the very thermal cracking you are trying to prevent. The counterintuitive move is to keep the surface warm so it stays closer to the core.
So mass concrete gets insulated, with blankets, insulating board, or by leaving the formwork on, to slow heat loss at the surface and hold the difference under the limit. The insulation does not keep the core cool. It keeps the surface from running cold and opening the gap. A useful trick is layering the insulation, several thinner layers instead of one thick one, so you can pull it off a layer at a time and bring the surface down gradually.
That gradual removal is the controlled cooldown, and it is where strip timing lives. You do not strip the forms or pull the insulation the moment the concrete is hard. You leave it on while the core is hot and bring the surface down slowly as the core cools, so the difference stays inside the limit the whole way. Strip too early and you create a sudden differential on a placement that was fine until you exposed it. The monitoring data, not the calendar, says when it is safe to come off.
Monitoring with thermocouples
You manage what you measure, and on a mass placement that means thermocouples or temperature sensors cast into the concrete, at least one at the core and one near the surface, at the locations the plan calls out. The core sensor catches the peak temperature against the 158F cap. The pair of core and surface sensors gives the difference against the 35F limit in real time. The thickest part of the element, where the heat concentrates, is the spot that decides the placement.
Place the surface sensor a couple inches inside the surface, not on it, so it reads the concrete and not the air, and log readings on a schedule through the peak and the cooldown, which can run a week or more. Many crews run the sensors to a datalogger that alarms when the difference nears the threshold, so someone can add insulation or adjust cooling before the limit is crossed instead of after. The maturity method, which estimates strength from the time-temperature history, often rides on the same sensors.
The data is only worth anything if someone acts on it. A difference climbing toward 35F is the signal to add a blanket layer or hold the forms on longer, not a number to file. The mistake is treating the sensors as a record for the closeout binder. They are an instrument for decisions you make while the concrete is still hot.
Lifts, placement rate, and weather
How the concrete goes in affects the heat too. Big placements often go in lifts, and the lift height and the rate are chosen so each lift can lose some heat before the next buries it, while still placing fresh on fresh to avoid cold joints. Place too slow and you get a cold joint between lifts where one layer set before the next arrived. Place too fast in too deep a lift and you stack heat with no chance to shed it. The plan sets the lift height and rate for the specific element.
Consolidate each lift into the one below it so the placement acts as one mass, not a stack of slabs. Vibrate through into the prior lift while it still responds, and watch the clock between trucks so the surface of the last lift has not stiffened past the point of knitting in.
Weather moves both limits. Hot weather raises the placing temperature and the peak, so precooling and night placement matter more, and the mix and delivery have to fight the ambient on the way to the forms. Cold weather is the sneaky one on mass concrete. The core still runs hot from hydration, but the cold air pulls the surface down fast and widens the difference, so the same insulation that protects an ordinary slab from freezing is also protecting a mass placement from cracking. The general hot and cold weather practices apply, with the differential as the extra thing to watch.
Curing alongside thermal protection
Curing and thermal protection overlap on a mass placement, and they are not the same job. Curing holds moisture in the concrete so the cement keeps hydrating and the surface gains strength. Thermal protection holds temperature so the core stays under the cap and the difference stays under the limit. On a mat, the blankets and the formwork left in place often do both at once, which is convenient but worth keeping straight in your head.
The conflict to watch is water. Wet curing with cool water on a hot mass surface can spike the difference, so the cooldown side of the plan can override the instinct to flood the surface. Insulating curing methods, blankets and sheet, usually fit mass work better than a cold water cure during the peak. The separate guide on curing methods and protection covers the methods, the durations, and the flooring bond-breaker trap in detail. Here the point is that the cure has to serve the thermal plan, not fight it.
Cure long enough that the surface is not a weak skin and protect long enough that the cooldown is controlled. On a high-SCM mass mix, both run longer than they would on an ordinary slab, because the strength comes in slower and the heat takes longer to leave.
Maturity, early strength, and what the structure needs
A hot core gains early strength fast, which sounds like a benefit and is partly a trap. The same heat that speeds the early strength is the heat that risks DEF and, if the strength comes too fast in a restrained element, can lock in stresses that crack on cooldown. Early strength is not the goal on mass concrete. Durability and crack control are.
The maturity method earns its place here. By tracking the time-temperature history at a sensor and correlating it to strength from lab-cured cylinders, maturity estimates in-place strength without breaking a cylinder for every decision, which helps time the form stripping and the controlled cooldown. ASTM has the standard for the maturity method, and it leans on the same thermocouples already in the concrete for thermal control.
The honest framing for a crew: do not chase early strength numbers on a mass placement. The cylinders will look strong because the core was warm. What the structure needs is a core that never went over the cap and a surface that never ran too far behind it. That is what the design is buying, and it does not show up on a 7-day break.
Field example: a data center foundation mat
A data center foundation mat shows how the pieces fit. Take a mat 8 ft thick, several thousand cubic yards, placed in summer. Untreated, that core would run far over 158F and the difference would blow past 35F within a day or two, so the placement is engineered end to end.
The mix goes out with a high slag and fly ash replacement to cut and slow the heat, and the cement content is held to what the strength needs and no more. The concrete is precooled, ice in the mix water and night placement, to start it cold so the peak lands lower. It goes in in controlled lifts at a rate the plan sets, consolidated lift into lift. The top and sides are insulated with blankets, the formwork stays on, and thermocouples at the core and near the surface feed a logger watched around the clock. When the difference creeps toward the limit, another blanket layer goes on. The insulation comes off in stages over days as the core cools, so the surface never runs too far behind.
None of that is improvised. It is the thermal control plan, written and accepted before the pour, executed and logged during it. The record at the end shows the peak core temperature stayed under the cap and the difference stayed under the limit the whole way. That record is the deliverable as much as the mat is.
What does the inspector check on a mass concrete pour?
The inspector and the QC tech check the temperature record first, because on mass concrete the temperature history is the acceptance. They want to see the peak core temperature stayed under the cap, the core-to-surface difference stayed under the limit through the peak and the cooldown, and the placing temperature met the plan. The thermocouple logs are the evidence, and a placement without them has no way to prove it met the limits.
Beyond the temperatures, the usual concrete QC still applies. The placing temperature is checked at the truck and at placement. Slump, air, and cylinders are taken per the spec. The lift heights and the placement rate are watched against the plan, and the cold joints between lifts are checked. The insulation and its strip timing are verified against the plan, not against the crew's hurry to get forms back.
Cores are the last resort, taken if the record shows a limit was exceeded or if cracking appears, to check for the internal damage the temperature data warned about. The point of all the upstream control is to never need them. When the temperature record is clean and the placement followed the plan, the acceptance is mostly already made before anyone drills.
What to document
The temperature record is the deliverable on a mass placement, so capture enough to defend it years later. Log the placement identity and date, the mix and its cementitious makeup, the placing temperature, the peak core temperature with its time, the peak difference with its time, the cooling and insulation used, the strip and cooldown timing, and who watched the data. If a limit was approached or exceeded, record what was done about it.
The reason is the same as everywhere else in concrete. When a question comes up later, a crack, a durability concern, an owner asking whether the mat was built right, the record is what answers it. A clean temperature history that shows both limits held is the proof the placement was sound. A missing record is an open question that never closes.
| Field to record | Why it matters |
|---|---|
| Placement ID, date, element | Ties the record to the specific mass pour |
| Mix and cementitious makeup | Shows the heat-reduction strategy used |
| Placing temperature | Drives the peak; first check against the plan |
| Peak core temperature and time | Proves the DEF cap was held |
| Peak core-to-surface difference and time | Proves the cracking limit was held |
| Cooling and insulation used | Documents the means that held the limits |
| Strip and cooldown timing | Shows the cooldown was controlled |
| Exceedances and actions taken | The honest record of any limit approached |
Common mistakes
- Running a mass placement with no thermal control plan, so nobody predicted the peak or set the action thresholds.
- Letting the core temperature run over the cap, commonly 158F, and inviting delayed ettringite formation that shows up years later.
- Letting the core-to-surface difference run over the limit, commonly 35F, and cracking the placement from the surface in.
- Stripping the forms or pulling the insulation early, which drops the surface fast and creates the difference you were avoiding.
- Placing with no thermocouples, so the peak and the difference are unknown and there is nothing to act on or to prove.
- Placing hot with no precooling, so the peak starts high and runs over the cap before anything can be done.
- Treating a borderline element as ordinary concrete because it is not obviously huge, then watching it crack.
- Cooling the surface to fight the heat, which widens the difference instead of helping.
Field checklist
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Standards and references
ACI 207, the guide to mass concrete, is the reference for what mass concrete is and how its heat behaves, with the cooling and insulating systems covered in ACI 207.4R and restraint and volume change covered elsewhere in the 207 series. ACI 301, the specifications for concrete construction, is where the maximum temperature and the maximum difference and the thermal control plan requirement commonly live, and the project specification can set its own limits on top of it. ACI 211 covers the mix proportioning behind the heat, and the mix design guide on this site goes into it.
The engineer of record governs. The temperature limits, whether the standard 158F and 35F apply or tighter or justified looser values are used, the acceptance of the thermal control plan, and the call on any borderline element all sit with the design professional, not the crew. ASTM standards cover the test methods that feed the QC, including the maturity method that estimates in-place strength from the temperature history, and the cement and SCM specifications behind the low-heat mix.
Section and document numbers shift between code cycles and the limits vary by project, so confirm the ACI editions and the actual numbers against the contract documents and the engineer before citing them on a submittal. The numbers in this guide are common spec values, not universal mandates. The thermal control plan, stamped and accepted, is the document that controls a given placement.
Units, terms, and conversions
Mass concrete temperature work moves between Fahrenheit and Celsius and a few terms that mean the same thing across documents.
The maximum core temperature is commonly written 158F or 70C, and the maximum difference 35F or 19.4C, the same limits in two scales. The temperature difference between core and surface is the differential, sometimes called the thermal gradient. Supplementary cementitious materials are SCMs, the fly ash and slag that replace part of the cement. Delayed ettringite formation is DEF. The peak is the highest core temperature reached, usually a day to a few days after placement.
- Mass concrete
- Any placement large enough that hydration heat must be managed to control cracking, often a least dimension of about 3 to 4 ft
- Heat of hydration
- The heat released as cement reacts with water, which accumulates in a thick element
- Differential (thermal gradient)
- The temperature difference between the core and the surface, commonly limited to 35F (19.4C)
- DEF
- Delayed ettringite formation, internal expansion and cracking from the core running too hot when young, commonly capped at 158F (70C)
- SCM
- Supplementary cementitious material, fly ash or slag, used to reduce and slow the heat of hydration
- Maturity method
- Estimating in-place strength from the time-temperature history at a sensor
FAQ
What is mass concrete?
Mass concrete is any placement large enough that the heat from cement hydration builds in the core faster than it escapes at the surface. ACI 207 defines it by behavior, not size, but a least dimension of about 3 to 4 ft is the common rule of thumb. Heat, not size alone, decides.
What is the maximum temperature for mass concrete?
The maximum core temperature is commonly held at 158F (70C) to avoid delayed ettringite formation, and a separate limit caps the core-to-surface difference at about 35F (19.4C) to avoid thermal cracking. When SCMs are used, the spec sometimes allows a higher cap. The engineer of record sets the actual limits.
Why insulate mass concrete instead of cooling the surface?
Because the cracking risk is the difference between core and surface, not the heat alone. The core stays hot for days no matter what. Cooling the surface widens the gap and drives thermal cracking, so you insulate to keep the surface warm and close to the core, holding the differential under the limit.
What is delayed ettringite formation?
Delayed ettringite formation, DEF, is internal expansion and cracking that appears months to years after a pour, caused by the core running over about 158F while young. Ettringite that could not form at high temperature forms later in the hardened paste, where it has no room, so it pushes and cracks the concrete from inside.
What is the maximum temperature differential for mass concrete?
The maximum core-to-surface temperature difference is commonly held at 35F (19.4C) to prevent thermal cracking, per ACI 301 and most project specs. The limit can be raised for confined or permanently cased elements at the engineer's discretion. It is the difference, not the absolute core temperature, that drives surface cracking.
How thick does a placement have to be to count as mass concrete?
There is no fixed thickness, but a least dimension of about 3 to 4 ft is the common rule of thumb. ACI 207 defines mass concrete by whether the hydration heat must be managed, so a rich, warm 2 ft element can behave like mass concrete. Heat decides, not the tape alone.
Does fly ash or slag reduce the heat in mass concrete?
Yes. Replacing a large fraction of the portland cement with fly ash or ground granulated blast furnace slag lowers the peak temperature and spreads the heat over more time, because the SCMs react slower. Replacement levels on mass concrete run high, sometimes 50 percent or more, set in the approved mix design.
What do I do if the temperature differential exceeds the limit?
Add insulation immediately to warm the surface and close the gap, and leave the forms and blankets on longer to slow the cooldown. Do not cool the core or strip anything. Then record the exceedance and notify the engineer, because the action and the deviation both belong in the thermal record.
Does a data center mat need embedded cooling pipes?
Usually not. Most large mats hold both limits with a low-heat high-SCM mix, precooling, and surface insulation. Embedded cooling pipes, the dam tool from ACI 207.4R, come in only when the element is so large that nothing else keeps the core under the cap, or when the schedule needs an active controlled cooldown.
Who writes the thermal control plan?
The contractor normally prepares the thermal control plan, or has it prepared, and submits it to the engineer of record, who reviews and accepts it. The contractor owns the means and methods: the cooling, insulation, and monitoring. The engineer owns the temperature limits and the acceptance. ACI 301 and most specs require the plan for mass placements.
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Codes cited in this guide
This guide is written and reviewed against the published standards below. Always confirm the current adopted edition with the authority having jurisdiction.