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DEPARTMENT OR UNIT NAME. DELETE FROM MASTER SLIDE IF N/A

ConcreteWorks Software For Iowa Use

Thermal Cracking

Picture courtesy of J.C. Liu, TxDOT

Achieving Durable Concrete

DurableConcrete

Concrete MixturesInfinite number of combinations of:• Aggregate type & quantity• Type & amount of cement• SCM use• Admixtures

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Quality concrete Multi-variate problem – rules of thumb can be inaccurate or unconservative

Preplanning Engineer – Best during design Contractor – Best during bidding

Required by specification

Why do we model temperature and stress?Why do we model temperature and stress?

Why is the bread surface cut before baking?

Self-Generated Restraint

Temperature Prediction

Tem

pe

ratu

re

Time

Heat of Hydration

Environmental Cycle

Heat Transfer

Tem

pe

ratu

re

Time

Surface

Core

≤ ΔT ?

Material FactorsCementitious Types/Composition

Cementitious FinenessCementitious ContentChemical Admixtures

w/cmFresh TemperatureAggregate Types

Construction FactorsElement Geometry/Size

InsulationForm PropertiesCuring Methods

Surface ColorCooling Pipes

EnvironmentAir Temperature

Wind SpeedRelative Humidity

Cloud CoverSolar Radiation

SoilWater Submersion

Heat Transfer

Generated Heat

Conducted Heat to soil

Solar Radiation and Radiation from Atmosphere

Convection to/from surface

Irradiation from Footing

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Heat Diffusion Equation

Generated Heat

Conducted Heat to soil

Solar Radiation and Radiation from Atmosphere

Convection to/from surface

Irradiation from Footing

T=temperaturek=thermal conductivityQH=heat generationρ=densityCp=specific heatT=time 𝑑

𝑑𝑥𝑘 ·

𝑑𝑇𝑑𝑥

𝑑𝑑𝑦

𝑘 ·𝑑𝑇𝑑𝑦

𝑑𝑑𝑧

𝑘 ·𝑑𝑇𝑑𝑧

𝑄 𝜌 · 𝐶 ·𝑑𝑇𝑑𝑡

Estimate Max Temperature

Schmidt Method

ConcreteWorks

Proprietary software (Finite Element Analysis)

Temperature Prediction Methods

Incr

eas

ing

Co

mp

lexi

ty

(Schindler, 2002)

Heat Evolved at Each Time Step

cr

ae

eecuh TTR

Et

ttWHtQ 11exp)()(

From Isothermal Calorimetry

From Literature

From Semi-Adiabatic Calorimetry

Role of Temperature in Hydration

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Temperature Sensitivity Example

Effect of temperature on bacteria growth in milk

Reaction Rate (S. Arrhenius, 1889) Where k = rate of reaction A = constant (=0) R = Universal gas constant (8.314) T = reference temperature Ea = Activation Energy

Arrhenius Equation

RTEAk a lnln

Temperature Sensitivity of Cement Reaction

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 10 20 30 40 50 60 70 80 90 100

Paste age (hours)

Deg

ree

of H

ydra

tion

5°C

15°C

23°C

38°C

60°C

y = -3538.3x + 8.5932R2 = 0.981

-5.5

-4.5

-3.5

-2.5

-1.5

0.0028 0.0030 0.0032 0.0034 0.0036 0.0038

ln(k

)

1/Temperature (1/k)

De

gre

e o

f Re

acti

on

Time from Mixing (hrs)

0

10

20

30

40

50

60

1 10 100 1000

Concrete Age (hours)

Adi

abat

ic T

empe

ratu

re R

ise

(°C

)0

12

24

36

48

60

72

84

96

108

Adi

abat

ic T

empe

ratu

re R

ise

(°F)

10ºC (50ºF)

20ºC (68ºF)

30ºC (86ºF)

Cementitious Content = 564 lb/yd3 (325 kg/m3)

40ºC (104ºF)

Type I CementC3S = 61.0C2S = 15.6C3A = 9.6C4AF = 6.0Blaine = 391 m2/kg

Effects of Curing Temperature on Adiabatic Temperature Rise

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(Schindler, 2002)

Heat Evolved at Each Time Step

cr

ae

eecuh TTR

Et

ttWHtQ 11exp)()(

From Isothermal Calorimetry

From Literature

From Semi-Adiabatic Calorimetry

0

10

20

30

40

50

60

70

32

50

68

86

104

122

140

158

0 24 48 72 96 120

Tem

pera

ture

(°C

)

Tem

pera

ture

(°F)

Time from Mixing (Hrs)

Cement Only

40% Class C Fly Ash

40% Class F Fly Ash

Adiabatic or Semi-Adiabatic Calorimetry

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

0.900

1.000

1 10 100 1000 10000 100000

Time (hours)

Degr

ee o

f Hyd

ratio

n

au = 0.900

au = 0.690

au = 0.500

e

ue tt exp*)(

–Degree of Hydration

Increasing

Figure Courtesy of Jonathan Poole

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

1 10 100 1000 10000 100000

Time (hours)

Deg

ree

of H

ydra

tion

t = 12.000

t = 26.774

t = 40.000

–Time Parameter

Increasing

Figure Courtesy of Jonathan Poole

e

ue tt exp*)(

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0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

1 10 100 1000 10000 100000

Time (hours)

Deg

ree

of H

ydra

tion

b = 1.250

b = 0.851

b = 0.450

e

ue tt exp*)(

–Slope Parameter

Increasing

Figure Courtesy of Jonathan Poole

Ea Trends – From 116x5 Isothermal tests

u, , , Hu Trends – From Semi-Adiabatic Data – 204 Semi-Adiabatic Tests

Validation performed using data from Schidler (2005), Ghe Li (2006), and field sites – 58 Semi-Adiabatic Tests

Variability of test methods is quantified – 63 Semi-Adiabatic Tests.

A brief overview of the trends seen in the study is shown next.

Model for Hydration Built From:

Variable Range of Tests Effect on Effect on Effect on u Fly Ash

(%Replacement) 15-55%

Fly Ash (CaO%) 0.7-28.9% CaO Varies

GGBF slag 30-70% Large Small Varies

Silica Fume 5-10% None None Small

LRWR 0.22-0.29% Varies Small Varies

WRRET 0.18-0.53% Large Large Large

MRWR 0.34-0.74% Large Small Varies

HRWR 0.78-1.25% None Small Large

PCHRWR 0.27-0.68% None Small Large

ACCL 0.74-2.23% Small None Varies

AEA 0.04-0.09% None None None

Variable Range of Tests Effect on Effect on Effect on u

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Increasing w/c 0.32-0.68 None None Large

Placement Temp 15-38 °C (50-100 °F) None None None

Increase Cement Fineness 350-540 m2/kg Small Small Varies

Variable Range of Tests Effect on Effect on Effect on u Proportions

Click checkboxes to use an SCM

Proportions

Don’t forget to enter CaOcontent of fly ashes

Check when admixtures used.

Heat Diffusion Equation

Generated Heat

Conducted Heat to soil

Solar Radiation and Radiation from Atmosphere

Convection to/from surface

Irradiation from Footing

T=temperaturek=thermal conductivityQH=heat generationρ=densityCp=specific heatT=time 𝑑

𝑑𝑥𝑘 ·

𝑑𝑇𝑑𝑥

𝑑𝑑𝑦

𝑘 ·𝑑𝑇𝑑𝑦

𝑑𝑑𝑧

𝑘 ·𝑑𝑇𝑑𝑧

𝑄 𝜌 · 𝐶 ·𝑑𝑇𝑑𝑡

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AggregatesMaterial Properties Input Screen

• Concrete thermal properties based on aggregate combination selected

• Can input your own thermal properties by checking box (for example, to use lightweight aggregate)

Aggregate TypeCoarse Aggregate Concrete CTERiver Rock 10.5 με/°CLimestone 6.6 με/°C

INVAR SIDE BAR

CROSSHEAD

Figures from Whigham 2005

Aggregates

Material

Coefficient of Thermal Expansion values used in ConcreteWorks (/°C)

Coefficient of Thermal Expansion from Emanuel and

Hulsey, 1977(/°C)

Hardened Cement Paste 10.8 10.8Limestone Aggregate 3.5 3.5 - 6Siliceous River Gravel and Sand 11 11 – 12.5Granite Aggregate 7.5 6.5 – 8.5Dolomitic Limestone Aggregate 7 7 - 10

pfaca

ppfafacaca

cteh VVVVVV

Construction Inputs

Default is use air temperature at placement

Options: steel, wood, and insulated steel formwork

*If insulated steel forms used, form insulation value appears

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ConcreteWorks Geometry: ColumnsHorizontal CrossSection Assumedfor RectangularColumn

ConcreteWorks Geometry: Footings

Verticalcross-sectionmodeledin 2-D

footing

Subbase Material

Density (kg/m3)

Thermal Conductivity (W/m/K)

Specific Heat (J/kg/K) Reference

Clay 1460 1.3 880

Incropera and Dewitt, 2002

Granite 2630 2.79 775Limestone 2320 2.15 810Marble 2680 2.8 830Quartzite 2640 5.38 1105Sandstone 2150 2.9 745Sand 1515 0.27 800Top Soil 2050 0.52 1840Concrete* - - -

Foundation Thermal Properties

*Concrete is assumed to have the same thermal properties of the concrete used on the footing, with a degree of hydration equal to 0.6.

ConcreteWorks Geometry: Soil on Sides of Footing

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Bent Cap

Vertical cross sectionmodeled in 2-d rectangularbent cap

T-shaped Bent Caps

Circular Column/ Drilled Shaft Mechanical PropertiesCheck to calculate stresses – can be slow, not recommended for more than 4-5 days of analysis

Maturity-Strength Relationship Parameters

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Environment Inputs (Weather)Weather data based on 30 year average values

Click here to manually change values

Service Life Modeling

Used for corrosion service life model inputs

Thermocouple Points

Allows the user to select where sensors would be placed to give realistic estimate of values they would measure

TxDOT (original software development) & IDOT for providing funding for this work

Acknowledgements

Go Gators!

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Design a concrete control plan for a 8 ft by 10 ft column placed in Ames in August 2020 to meet IDOT standards.

Next, determine any changes that would be needed to place the same column in January, 2021 in Ames.

*Pay attention to the difference it makes where the temperature sensor is placed

Problems to Work Out After Lunch Design a control plan for concrete footing that is 20 ft by 30 ft by 8 ft

thick in Des Moines in March. Use limestone subbase. What difference do you get between 1D and 2D analysis?

What about with a 10 ft wide footing – what difference do you get between a 1D and 2D analysis?

Problems to Work Out After Lunch

You want to place a concrete footing that is 30 ft by 20 ft by 6 ft thick. It is August in Des Moines, and you expect a storm after 2 days to lower the high temperature to 60°F and the low temperature on day 2 to 45°F. Design a system that will still meet IDOT standards.

Problems to Work Out After Lunch