Concrete Temperature Calculator

1. Choose F and lb or C and kg, then enter the temperature of the aggregate, cement and mixing water.
2. Enter the weight of the aggregate, cement and added water for the batch, plus any free moisture on the aggregate and any ice.
3. Optionally pick a limit to compare with, then read the mixed temperature and the verdict.

Here is what each result means:

A concrete temperature calculator predicts how warm or cold a batch of concrete will be when it comes out of the mixer, using the temperature and weight of each ingredient. Concrete is mostly aggregate, so the stockpile temperature matters most, followed by the mixing water.

Producers and contractors use it to decide whether to chill the water, add ice or heat the water before a pour, because hot concrete loses slump quickly and cold concrete sets and gains strength slowly. It predicts the temperature at the mixer, not the temperature after hauling or in the forms, and it is not a strength calculator. For strength by age, see the concrete curing time calculator, and for the mix water itself the water cement ratio calculator.

The equation is a heat balance. Each ingredient contributes its weight times its temperature, and dry aggregate and cement are weighted by 0.22 because they hold less heat than the same weight of water. The Portland Cement Association prints it in degrees F and pounds with a 112 on the ice term, and in degrees C and kilograms with an 80.

1. Multiply the aggregate and cement temperatures by their weights, add them, and multiply by 0.22.
2. Add the mixing water and free-moisture terms, each a temperature times a weight.
3. Subtract 112 times the ice weight (80 in C and kg).
4. Divide by 0.22 times the aggregate and cement weight plus the water, free moisture and ice weights.

With no ice the ice terms drop out, which is the usual form of the equation. Ice is counted as replacing mixing water, pound for pound, so enter only the liquid water in the water field. This tool treats the free moisture on the aggregate as being at the aggregate temperature.

Take a hot-weather batch with 3,000 lb of aggregate at 95 F, 564 lb of cement at 120 F, 260 lb of mixing water at 80 F and 60 lb of free moisture on the aggregate.

Calculation: the numerator is 0.22 x (95 x 3,000 + 120 x 564) = 0.22 x 352,680 = 77,589.6, plus 80 x 260 = 20,800, plus 95 x 60 = 5,700, which totals 104,089.6. The denominator is 0.22 x (3,000 + 564) = 784.08, plus 260, plus 60, which is 1,104.08. The mix comes out at 94.3 F.

Now replace 100 lb of the water with ice, so 160 lb of liquid water and 100 lb of ice. The numerator becomes 77,589.6 + 80 x 160 + 5,700 – 112 x 100 = 84,889.6, the denominator stays 1,104.08, and the mix drops to 76.9 F, about 17.4 F cooler.

Aggregate Temperature

Aggregate is the largest share of the batch, so it has the biggest pull. In the worked example, each 1 F change in the aggregate moves the result about 0.65 F, because its weight and its free moisture both count.

Mixing Water Temperature

Water is a small share of the weight but carries far more heat per pound, so each 1 F change in the water moves the result about 0.24 F in the example. It is also the easiest ingredient to chill or heat.

Cement Temperature

Each 1 F change in the cement moves the result about 0.11 F in the example. PCA notes that cement is often about 30 to 70 F warmer than the average ambient air temperature, so measure it instead of guessing.

Ice

Ice cools twice, by being cold and by absorbing heat as it melts, which is why the 112 term is so large. It replaces mixing water pound for pound, and all of it must be melted before discharge.

Free Moisture on the Aggregate

Wet stockpiles add water at the aggregate temperature, which pulls the result toward the aggregate temperature. Enter it so the water and the aggregate are not double counted.

The sources give a few limits worth comparing against. They are reference points, and the project specification controls.

TIP 18 also advises the producer to target a temperature below the specified maximum to allow for a rise of 1 to 5 F during delivery, and CIP 27 says concrete should not exceed the cold-weather temperatures by more than 20 F. The 35 C used in metric mode is a direct conversion of 95 F, not a figure printed in the source.

Ice gives the biggest cut, chilled water a smaller one, and cooling the aggregate works through the largest share of the batch.

Mixed concrete that is slow to deliver warms up on the way, which the concrete truck calculator helps plan, and a mix built to set in minutes follows different rules, covered by the fast setting concrete calculator.

Planning a Hot-weather Pour

Check whether the batch will clear the maximum and how much ice or chilled water it would take to get comfortably under it.

Planning a Cold-weather Pour

See how hot the mixing water needs to be for the concrete to reach the minimum for its section size, and whether heating the water alone is enough.

Comparing What to Change

Change one ingredient at a time to see whether the water, the aggregate or the ice gives the most movement for the effort.

1. Entering Ice as Part of the Water

The equation counts ice separately. Enter only liquid water in the water field, or the ice is counted twice.

2. Guessing the Cement Temperature

Cement is often warmer than the air, so assuming the ambient temperature can understate the result.

3. Ignoring Free Moisture

Wet aggregate carries water that changes the balance. Leaving it out of a wet stockpile shifts the answer.

4. Mixing Units

Pounds and degrees F go together, as do kilograms and degrees C. The toggle converts the numbers for you, but typing a C temperature in F mode gives nonsense.

5. Treating the Result as the Placed Temperature

The equation gives the temperature at the mixer. Hauling, waiting, forms and weather change it before and after placement.

6. Using It as the Only Check

Measure the concrete as delivered. The estimate helps you plan the batch, not replace the thermometer.

The equation is applied exactly; how close it is to the real batch depends on how well you know each temperature and weight.

The Portland Cement Association gives it as a weighted heat balance: 0.22 times the aggregate and cement temperature-weight sums, plus the water and free-moisture terms, minus 112 times the ice weight, divided by 0.22 times the aggregate and cement weight plus the water, free moisture and ice weights, in F and lb.

It weights dry aggregate and cement because they hold less heat per pound than water. The Portland Cement Association equation applies it to the aggregate and cement terms and leaves water at full weight.

NRMCA says ice can reduce concrete temperature by up to 20 F (12 C), and PCA gives the same figure of about 11 C (20 F), with ice typically used for up to 80 percent of the mixing water. The actual cooling depends on the mix.

NRMCA says chilled water can reduce concrete temperature by up to 10 F (6 C). Ice cools more because melting ice also absorbs heat.

NRMCA TIP 18 says ACI 301 and ACI 305.1 state a maximum of 95 F, which the project specification can modify. It also advises targeting lower to allow a 1 to 5 F rise during delivery.

NRMCA CIP 27 recommends 55 F (13 C) as placed for sections under 12 in, 50 F (10 C) for 12 to 36 in, and 45 F (7 C) for 36 to 72 in. Fresh concrete freezes below about 25 F.

No. Enter only the liquid water in the water field and the ice in its own field. The equation counts ice as replacing mixing water pound for pound, so counting it in both places double counts it.

Not exactly. It is the temperature right after mixing. NRMCA notes a 1 to 5 F rise during delivery in hot weather, and cold or windy conditions cool the load, so measure what arrives.

The usual causes are a wrong cement or aggregate temperature, unmeasured free moisture, or heat from mixing and hydration, which the equation leaves out. Check the inputs first, then measure the concrete.

No. The calculation runs entirely in your browser and nothing you enter is stored or sent anywhere.

• Mass Concrete for Buildings and Bridges (EB547) (Portland Cement Association; the heat-balance equation with ice, page 16).
• CIP 27 Cold Weather Concreting (NRMCA; cold-weather minimum temperatures and freezing point).
• TIP 18 Managing Concrete Temperature for Specified Requirements (NRMCA; hot-weather maximum and temperature rise during delivery).
• CIP 12 Hot Weather Concreting (NRMCA; ice and chilled water cooling).