Heat of Hydration in Mass Concrete

Heat of Hydration in Mass Concrete

“Raft Foundation and Thick Walls”

Khaldoon SlaiaiConcrete Research ManagerSaudi Readymix Concrete company

HOH Basics – Mass Concrete Definition Mass concrete is defined by ACI “Any volume of concrete

with dimensions large enough to require that measures

be taken to cope with generation of heat from hydration

of the cement and attendant volume change to minimize

cracking.”Examples:• Dam• Raft Foundation• Pile Cap.• Thick Wall.• Thick column.• Deep Slap.

Cement Composition “Type I - OPC”

Main Chemical Cement Reactions with Water

HOH generated from cement main ingredients

% of HOH generated from cement main ingredients

HOH Main Concerns

• Differential Temperature:

Crack Concern: Thermal Cracking

• Max Temperature: Durability Concern: DEF Cracking “DEF = Delayed

Ettringite Formation”

Strength Concern : Effects on Ultimate Strength

Typical Temperature Curve in Mass Concrete

Placement Temperature

Maximum Temperature (Tmax)

Maximum Temperature “Tmax” = Placement

Temperature of Concrete + Temperature Rise due to

Heat of Hydration

Factors Affecting Maximum Temperature “Tmax” of Concrete

Cement Content.

Type and source of cementitious materials.

Section Thickness.

Concrete Placing Temperature.

Formwork and insulation.

Ambient Temperature.

Mix Design

Mix Design

Structural Design

Supplier facility

Contractor facility

Factors Affecting Tmax

Rate of Temperature Rise: Time of Occurrence of Tmax

Main Factors affecting:

Cement Fineness and chemical composition.

Cement Quantity

Type of Cementitious materials added.

Type of Admixture added.

Structure Thickness.

In general the slower rate of temperature rise the better to avoid the thermal cracking

Period required for Temperature dropping from the maximum value

Main Factors affecting :

Structure Thickness

Type of Surface Insulation.

Period required for Temperature dropping from the maximum value

Main Factors affecting :

Structure Thickness

Type of Surface Insulation.

Durability Concern of Tmax “DEF Cracking”:

DEF may occur in mass concrete placement because the high internal temperature (core temperature more than 70C). The mechanism appears to follow this sequence:

1. High Temperature disrupt the normal formation of ettringite causing the sulfate and alumina to be adsorbed by CSH get in the cement paste.

2. After concrete has cooled to ambient conditions, the sulfate can later desorb in the presence of moisture and react with calcium monomsulfoaluminate to form ettringite.

3. This “delayed” ettringite can then exert great pressure because if forms in the limited space of a rigid structure in an expansive reduction.

4. Theses high pressures within the paste can cause internal micro-cracking and macro-cracking.The reformation of ettringite requires a

substantial quantity of water, without free water the DEF reaction can not readily occur.

Strength Concern of Tmax “Reduction in Ultimate Strength”:

It has been recognized for many years that if concrete is heated too rapidly during the early period of hydration, the long term properties may be adversely affected.

Thermal Cracking

Thermal cracks occur when:

The tensile stress due to thermal stress is greater than The

tensile strength of concrete.

Thermal cracks occur when:

The thermal strain is greater than the tensile strain capacity

of the concrete

In other words

Thermal Strain formula

∝𝑐= 𝐶oefficient of thermal expansion of concrete

𝑯𝒊𝒈𝒉𝒆𝒓 ∝ 𝒄→𝑯𝒊𝒈𝒉𝒆𝒓 𝑺𝒕𝒓𝒂𝒊𝒏 →𝑯𝒊𝒈𝒉𝒆𝒓 𝑪𝒓𝒂𝒄𝒌𝒊𝒏𝒈 𝑹𝒊𝒔𝒌 𝑯𝒊𝒈𝒉𝒆𝒓 ∆𝑻→𝑯𝒊𝒈𝒉𝒆𝒓 𝑺𝒕𝒓𝒂𝒊𝒏 →𝑯𝒊𝒈𝒉𝒆𝒓 𝑪𝒓𝒂𝒄𝒌𝒊𝒏𝒈 𝑹𝒊𝒔𝒌

Temperature Differential

Temperature gradients are produced when the heat being generated in the concrete is dissipated to the surrounding environment causing the temperature at the surface of the concrete to be lower than the temperature at interior of the concrete

Differential Temperature ()Differential Temperature () = Max Temperature in Mass

Structure – Min Temperature in Mass structure AT ANY

TIMEInternal restraint is a result of differential temperature changes within an element.

It may lead to both surface cracking and internal cracking that may not be observed from the surface.

Differential Temperature ()

Heating COOLING

Surface Thermal Cracking during Heating Period

Since the temperature at the core of mass concrete is higher due to the heat of hydration, expansion will occur.

This expansion is restrained by the cooler exterior concrete that doesn’t expand as rapidly as the core.

The restraint will cause compressive stresses to develop at the core and tensile stresses at the surface.

It leads to increase the cracking potential at or close to the surface of the concrete.

In Summary: As heating occurs, the surface is subject to tensile stresses as the center of the pour gets hotter and expands to a greater extent.

Surface and/or Internal Thermal Cracking during Cooling Period

As cooling occurs

There is a stress reversal and the surface cracks generally reduce in width. At the same time tension is generated at the center of the pour as it cools more than the surface andinternal cracking may occur.

∝𝒄=𝑪𝐨𝐞𝐟𝐟𝐢𝐜𝐢𝐞𝐧𝐭𝐨𝐟 𝐭𝐡𝐞𝐫𝐦𝐚𝐥𝐞𝐱𝐩𝐚𝐧𝐬𝐢𝐨𝐧 𝐨𝐟 𝐜𝐨𝐧𝐜𝐫𝐞𝐭𝐞

A concrete with a low coefficient of thermal expansion can significantly reduce the risk of thermal cracking

The value of αc can be estimated from the coefficients of thermal expansion of the aggregates .

some aggregate

Aggregate Type Thermal expansion coefficient (microstrain/°C)

Quartzite 14

Gravel 13

Granite 10

Basalt 10

Limestone 9

Marble 7

Lytag (lightweight) 7

𝐋𝐨𝐰𝐞𝐫 𝐓𝐡𝐞𝐫𝐦𝐚𝐥𝐒𝐭𝐫𝐚𝐢𝐧→𝐋𝐨𝐰𝐞𝐫𝐑𝐢𝐬𝐤𝐨𝐟 𝐭𝐡𝐞𝐫𝐦𝐚𝐥𝐂𝐫𝐚𝐜𝐤𝐢𝐧𝐠

Conclusion

To have same risk of thermal cracking: using concrete with lower coefficient of thermal exemption allows more differential temperature to be applied

𝐋𝐨𝐰𝐞𝐫 𝐓𝐡𝐞𝐫𝐦𝐚𝐥𝐒𝐭𝐫𝐚𝐢𝐧→𝐋𝐨𝐰𝐞𝐫𝐑𝐢𝐬𝐤𝐨𝐟 𝐭𝐡𝐞𝐫𝐦𝐚𝐥𝐂𝐫𝐚𝐜𝐤𝐢𝐧𝐠

Conclusion

To have same risk of thermal cracking: using concrete with lower coefficient of thermal exemption allows more differential temperature to be applied

Effect of Aggregate Type on Tensile Strain Capacity of Concrete

The tensile strain capacity is the maximum strain that the concrete can withstand without a continuous crack forming.

The tensile strain capacity may be measured directly or derived from measurements of the tensile strength and the elastic modulus of the concrete

Allowable based on Aggregate Type

Source: CIRIA C660 Early-age thermal crack control in concrete

Worst Agg. Type

Agg. in ER & CR

NOT Available in Saudi Arabia

)NOT used in Concrete Production in SA(

Agg. in WR

Project Specifications of Mass Concrete&

Method of Compliance

Typical Limits usually specified in project Specifications

The max temperature at any point within the pour shat not exceed 70 °C

WHY..….To avoid DEF and Negative affect on ultimate strength

The max temperature differential “shall not exceed 20 °C. WHY…. To avoid thermal CrackingWHY 20 °C: Designers at design stage usually have no idea about the type of aggregate will be used in concrete so……..

They usually take in consideration the worst scenario which it is the use of concrete with Gravel Aggregate which means the allowable is 20°C

Designers Point of View

It is recognized that at the design stage there may be limited information available and a simplified design approach which uses conservative default values is provided. This approach will lead to a conservative design.

Mean Methods for Controlling of Maximum Temperature ()

Control Method Responsibility RestraintsMix Design:• Use the minimum amount

of Cement • Use Cementitious

Additives at the right percentage

Designer, Consultant, Contactor, Supplier

• Specifying Minimum Cement content.• Specifying strength at 28 days.• Preventing the use of cementitious

additives by the contractor (Cost).• Specifying special type of additives at

specified percentage.

Placing Temperature Contactor, supplier

• Maximum temperature not specified in the specification.

• Specifying unsuitable placing temperature for thick structure such as “32C”

• Contractor does not want to pay the cost of Ice to be used for reducing the placing temperature.

• Supplier does not have a facility to produce low concrete temperature

Other Restraints may be affect the reduction of

• Using Special Type of Formwork by contactor.• Using concretive insulation layers for surface insulation

due to specifying concretive limit.• High ambient temperature

Mean Methods for Control of ()

Control Method Responsibility RestraintsReduce the heat loss from concrete surfaceSurface insulation “Applying insulation layers”

Contactor • Cost of insulation layer.• Applying insulation layer for un-

appropriate period “short Period” (heat shock)

Reduce the temperature of the core, Cool Down the core by use of cooing pipe

Contactor, • “expansive solution”, applied in dam structures only

Using Suitable Formwork Type (such as plywood)Especially for wall

Contactor • Construction Restraints.

Mix Design Concepts for reducing TmaxHeat of hydration generates from the reaction of cement and water, reactions of cementitious materials such as Fly ash, GGBFS and silica fume generate heat of hydration also but with lesser amount compered with the reaction of cement and water.

Aggregate are inert materials and do not contribute in generating any heat of hydration

Most admixture do not contribute in generating of heat of hydration, some of them may affect the rate of reaction but not contribute in heat generationSo……

The concept of mix design for reducing Tmax depends on using the lowest amount of cementitious materials.

Design Concepts for reducing Recuing Tmax helps in reducing when applying suitable type of surface insulation.

For Saudi Arabia conditions, mix design usually play a little contribution in reducing

So……

The

Design Concepts for increasing Tensile Strain Capacity of Concrete

Use the type of aggregate that produce lower coefficient of thermal expansion such as Limestone aggregate.

Applying design methods to increase the tensile strength of the concrete at early age without increasing the cementitious content (such as the use of fiber)

OPC Mixes for Mass Concrete “No Additive to be used”In general, the estimated temperature rise for OPC is (12.5 – 15 °C/100 kg) based on the thickness of the structure:

Structure Thickness (mm)

Estimated temperature rise (°C/100 kg )

1000 12.51500 13.52000 142500 14.53000 14.8

GGBFS Mixes for Mass ConcreteCIRIA C660 Suggests the following figures for estimating the temperature rise for GGBFS mixes in mass concrete

GGBFS Mixes benefits in mass concrete:

Reduce Tmax.

Lower Rate of Heat Generation.

Delay the setting time of concrete.

Fly Ash Mixes for Mass ConcreteCIRIA C660 Suggests the following figure for estimating the temperature rise for Fly Ash mixes in mass concreteBenefits of Fly Ash Mixes:

Reduce Tmax.

Lower Rate of Heat Generation.

Delay the setting time of concrete.

Silica Fume Mixes for Mass Concrete

It is generally recognized that the heat generated by silica fume concrete is

similar to that of OPC at the same Cementitious material content. More

recent measurements have supported this concept.

The cementing efficiency is much higher than that of OPC, and silica fume

may be used to achieve the same strength with a reduced Cementitious material

content hence reducing Tmax

Ground Limestone Mixes for Mass Concrete

In terms of generating heat Ground Limestone Powder may be assumed to have minor to little effect of the heat of hydration.

Ground Natural Pozzolans Mixes for Mass Concrete

In terms of generating heat Ground Natural Pozzolans may be assumed to have minor to little effect of the heat of hydration.

Use of Cementitious tolerates specifying higher TmaxUse of GGBFS and Fly Ash reduce the negative effects of high temperature on the ultimate strength of concrete

The relationship between the peak temperature and the strength (relative to the 28-day cube) using OPC cement , Portland limestone cement (PLC), and combinations of OPC cement with 30 per cent fly ash cement (P/FA-B) and 50 per cent ggbs (P/B)

Use of Cementitious tolerates specifying higher Tmax

The following guidance is given in BRE IP11/01 (BRE, 2000) in relation to the risk of DEF.Tmax < 60 °C no riskTmax < 70 °C very low riskTmax < 80 °C low risk

These above limits apply to Portland cement concretes. BRE IP11/01 states that Fly Ash at levels of > 20 per cent or GGBFS at levels of > 40 per cent will prevent DEF-induced expansion in concrete subject to peak temperatures of up to 100 °C.

The risk of DEF may be reduced most effectively by the use of fly ash of ggbs in suitable quantities which will have the combined effect of both reducing the temperature rise and increasing the temperature at which DEF will occur.

Use of GGBFS and Fly Ash reduce the negative effects of DEF

Other Factors may be considered in mix design Strength Age: convince the customer to specify the

strength at 56 days or 90 days instead of 28 days “if possible” to be able to use lower cementitious materials content.

W/CM: use the lowest possible W/CM, this allows using the lowest cement content (Less Tmax) and increase the tensile strength of concrete (less thermal risk).

Aggregate: use limestone aggregate “if possible”.

Placing Temperature: use the lowest placing temperature “if possible”.

Fiber: use fiber if possible to increase the tensile strength of concrete.

Reducing () by Applying Insulation Layer on raft foundation surface.

Reducing () by Applying Insulation Layer on raft foundation surface.

Reducing () by Selecting the right Formwork Type in Thick Walls

The Risk of the use of Excessive insulation

Using excessive or unnecessary insulation to minimize temperature differentials may lead to an increase in the mean temperature of the structure and hence the risk of thermal cracks. It may lead to thermal shock in case of removing the insulation at inappropriate time.

Heat ShockRemoving insulation layers in raft foundation or formwork in thick walls too early increases the deferential temperature rapidly and my lead to thermal cracking. This is called “Heat Shock”

Modeling of HOH by using IQ-Drum

and Quadrel Simulation tool “iTest”

Important Definitions

Adiabatic condition: adiabatic environment is the environment perfectly thermally insulated.

Heat is Energy, Heat Quantity is measured by (Kj/Kg), it is Quantity dependent variable “depends on the quantity of .

Temperature: does not depend on the quantity of the substance measured by °C.

Heat Flow: Heat flows in the direction of decreasing temperature. (for concrete, generally from the interior to exterior, since the interior tend to be hotter.

Adding Heat to a substance increases its temperature.

IQ-DrumIQ-Drum is a semi-Adiabatic Calorimeter, a plastic cylinder 150×300mm filled by concrete then place in its place in IQ-drum then connected to thermo-sensor attached to the IQ-drum by a thermocouple.IQ-Drum Measurements:IQ-drum measures: (every 15 minutes)• sample temperature (measured in °C) and • the rate of heat loss from the calorimeter (measured in millivolt) .IQ-Drum Results:IQ-drum compute • The hydration rate and • heat amounts by compensating for heat loss to reach to the adiabatic

conditions.

IQ-Drum

IQ-Drum Test Start-up Define Mix proportion in Quadrel iService. Define Trial Mix “sample log”. Define IQ-drum Test. Enter the size of cylinder mold Enter the weigh of concrete inside cylinder

mold. Click “Start” button.

IQ-Drum Measurement Report

Heat Profile Developed by IQ-drum MeasurementTwo Heat profiles will be developed by the IQ-drum measurements:

AHS: Adiabatic Heat Signature = Adiabatic heat of hydration (Kj/Kg) and its rate (Kj/kg.hr) versus the maturity curing age (Maturity Hours).

ATR = Adiabatic Temperature Rise = Adiabatic temperature (°C) and its rate (°C/hr)versus the maturity curing age.

Maturity = Equivalent curing age at 20 °C compute by the Arrhenius rate equation.

AHS – Adiabatic Hydration Heat and its Rate

ATR– Adiabatic Temperature Rise and its Rate

Simulation of Mass Concrete Structure Element

To simulate the heat of hydration in mass concrete structure elements usually we need the following: Heat of Hydration profile “heat of hydration Signature”: which we get it by IQ-

drum test measurements. Structure thickness. Concrete Placing Temperature. Ambient temperature profile during simulation period. Soil Information: the structure under the element will be casted. Work Plan. Which means surface curing plan in raft foundation and thick slab, or

formwork type in thick walls and columns.

Simulation of Mass Concrete Structure Element

What is the difference between Quadrel Simulation and some other simulation programmers. There are a lot of cheap simulation programmers available and do not require

a specific calorimeter device such IQ-drum, they are developed based on default heat of hydration profiles, for instance the module developed by CIRIA 660 depends on adiabatic curves derived from extensive testing at the University of Dundee.

The degree of errors in simulation may be significant if the materials actually used differ from those used by the University of Dundee.

Quadrel simulation depends on the actual heat profile for the mix will be actually in the project, which built by IQ-drum test measurements.

Quadrel Simulation gives more accurate results because it depends on the mix proportion and materials will be used in the actual pouring.

Simulation Parameters

Work Plan Parameters

Simulation Chart – Max, Min and Curves

OPC cement only.Cement Content = 500 Kg.Structure Thickness = 3 m.Placing Temp. = 30 °C.Simulation Period = 7 days.

Water Curing (7 days)

Simulation Charts at specific Depth

Max Temperatures Curve

Temperatures Curveat 2500 mm depthMin Temperatures

Curve

Differential Temperatures Curve

OPC cement only.Cement Content = 500 Kg.Structure Thickness = 3 m.Placing Temp. = 30 °C.Simulation Period = 7 days.


Effect of Structure Thickness

OPC cement only.Cement Content = 500 Kg.Placing Temp. = 30 °C.Simulation Period = 7 days.

500 mm

7517

1000 mm8827

2000 mm9733

3000 mm99.441


Important Points related to Thickness Effect

Thickness increases Tmax increases and increases . Thickness increases Longer Time of Tmax to achieve. Thickness increases Longer time to Tmax to drop. Thickness increases Longer time to to achieve. In pervious slide for 500 and 1000 mm thickness achieved during heating period

while in 2000 and 3000 mm achieved during cooling period. At 7 days (end of water curing plan) for 500 mm: Tmax = 40.4 °C , = 2.4 °C for 1000 mm: Tmax = 55.8 °C , = 11.3 °C for 2000 mm: Tmax = 79.4 °C , = 28.1 °C for 3000 mm: Tmax = 92.8 °C , = 40 °C

Important Points related to Thickness Effect

after 7 days (concrete is uninsulated, water curing plan stopped) for 500 mm: Tmax = increased (↑1°C), = 5.4 °C (↑ 3°C), for 1000 mm: Tmax = Not Increased , = 15.9°C (↑4.6°C). for 2000 mm: Tmax = Not Increased, = 35.6°C (↑7.5°C), for 3000 mm: Tmax = 92.8°C (↑1°C), = 48.4 °C (↑8.4°C),

Effect of Placing Temperature

Tplacing = 30 C, Tmax = 99.3 C, = 40.7 C Tplacing = 25 C, Tmax = 94.4 C, = 38 CTplacing = 20 C, Tmax = 90.4 C, = 35 C.

Conclusions:

• There is a liner relationship between Tplacing and Tmax,

• 1 C increment in Tplacing = 1 C increment in Tmax

• Tplacing affects on also, Tplacing increases increases

30 C

25 C

20 C

Water Curing (7 days)Tplacing = 30 C

Effect of Ambient Temp. (Typical Values in Saudi Arabia)

Dammam

Riyadh

Jeddah

Effect of Ambient Temperature – 3 m foundation

Tambient = (45 – 30) : Tmax = 99.4 C, ∆Tmax = 40.7 CTambient = (35 – 20) : Tmax = 98.7, ∆Tmax = 46.9 CTambient = (25 – 10) : Tmax = 98.1, ∆Tmax = 53.3 C

Conclusions:• Change in ambient temperature has

significant effect on ∆Tmax • Change in ambient temperature has minor

effect on Tmax (for thick sections).• Change in ambient temperature has an

effect on Tmax (for then sections).

45 - 30 C

35 - 20 C

25 - 10 C


Effect of Ambient Temperature – 1 m foundation

Tambient = (45 – 30) : Tmax = 99.4 C, ∆Tmax = 40.7 CTambient = (35 – 20) : Tmax = 98.7, ∆Tmax = 46.9 CTambient = (25 – 10) : Tmax = 98.1, ∆Tmax = 53.3 C

Conclusions:• Change in ambient temperature has

significant effect on ∆Tmax • Change in ambient temperature has minor

effect on Tmax (for thick sections).• Change in ambient temperature has an

effect on Tmax (for then sections).

45 - 30 C

35 - 20 C

25 - 10 C


Effect of Pouring Time

07:00 : Tmax = 99.6 °C, ∆Tmax = 40.7 C15:00 : Tmax = 99.4 °C , ∆Tmax = 40.7 C23:00 : Tmax = 99.2 °C, ∆Tmax = 40.7 C

Conclusions:• Pouring time has no effect on ∆Tmax • Pouring time has a negligible effect on

Tmax for same placing temperature

Important:• Pouring time has more effect on placing

temperature which has direct effect on Tmax

07:00

23:00

15:00


Effect of Soil information – Concrete with various temperatures- 3 m foundation

Tsoil = Tplacing = 30 C : Tmax = 99.4 °C, ∆Tmax = 40.7 CTsoil = 45 C : Tmax = 99.9 °C , ∆Tmax = 41.4 CTsoil = 15 : Tmax = 99 °C, ∆Tmax = 39.7 C

Conclusions: for thick Structure• Tsoil has minor effect on ∆Tmax • Tsoil has minor effect on Tmax.


Tsoil = 45 C

Tsoil = 30C = Tplacing

Tsoil =15 C

Effect of Soil information – Concrete with various temperatures- 1 m foundation

Tsoil = Tplacing = 30 C : Tmax = 87.6 °C, ∆Tmax = 27.2 CTsoil = 45 C : Tmax = 90.9 °C , ∆Tmax = 23.6 CTsoil = 15 : Tmax = 83.7 °C, ∆Tmax = 43 C “Impractical case as it is very rare that Tplacing 30 and Tsoil 15”

Conclusions: in thin structure• Tsoil has significant effect on both Tmax

and ∆Tmax


Tsoil =15 C

Tsoil = 30C = Tplacing

Tsoil = 45 C

What if Tsoil = 45C, Tambient = 45 – 30 and Tplacing = 20C, 3 m foundation


Surface

SoilTmax

∆T

Tmin

What if Tsoil = 45C, Tambient = 45 – 30 and Tplacing = 20C, 3 m foundation


Surface

SoilTmax

∆T

Tmin

Effect of Work Plan – 3m Raft Foundation

Work Plan: wind speed= 3 m/sPermanently Uninsulated Surface:

Tmax = 99.2 C, ∆Tmax = 54.6 C

Work Plan: wind speed = 3 m/sUninsulated for 16 hours.2 layer of plastic sheet for 168 hours.

Tmax = 99.2 C, ∆Tmax = 51.5 C

Tplacing = 30 C


Work Plan: wind speed = 3 m/sUninsulated for 16 hours.1.8 cm Plywood for 168 hours.

Tmax = 99.9 C, ∆Tmax = 33 C

Work Plan: wind speed = 3 m/sUninsulated for 16 hours.2 cm Water Curing for 168 hours.

Tmax = 99.5 C, ∆Tmax = 40.6 C

Tplacing = 30 C


Work Plan: wind speed = 3 m/sUninsulated for 16 hours.2 cm StyroFoam for 168 hours.

Tmax = 100 C, ∆Tmax = 33.4 C

Work Plan: wind speed = 3 m/sUninsulated for 16 hours.2 cm EthaFoam for 168 hours.

Tmax = 100 C, ∆Tmax = 33.5 C

Tplacing = 30 C


Work Plan: wind speed = 3 m/s

NO Work Plan: Structure perfectly insulated

Tmax = 101.3 C, this is the maximum Tmax can be reached

∆Tmax = 33.4 C, this is the minimum ∆Tmax can be reached

PERFECTLY

INSULATED

Heat Loss will be

through Soil Only “No Loss from the surface”

Tplacing = 30 C


Tplacing = 30 C

Work Plan: wind speed = 3 m/sPermanently Uninsulated Surface:

Tmax = 88.4 C, ∆Tmax = 34.6 C

Work Plan: wind speed = 3 m/sUninsulated for 16 hours.2 cm water curing for 168 hours.

Tmax = 88.3 C, ∆Tmax = 27 C

Effect of Work Plan – 1m Wall

Work Plan: wind speed = 3 m/s1.8 cm Plywood Formwork.Striking Time = 168 hours

Tmax = 93 C, ∆Tmax = 14.4 C

Work Plan: wind speed = 3 m/s0.4 cm Steel Formwork.Striking Time = 168 hours

Tmax = 89.8 C, ∆Tmax = 34.8 C

Tplacing = 30 C

Heat Shock: removing Insulation after 3 days – 3m Foundation

Tplacing = 30 C


Tmax = 99.9 C, ∆Tmax = 33 C


Tmax = 99.9 C, ∆Tmax = 54 C

Heat Shock: Formwork Striking after 3 days – 1m Wall

Tplacing = 30 C


Tmax = 93 C, ∆Tmax = 14.4 C


Tmax = 93 C, ∆Tmax = 30 C

Extensive Insulation to achieve conservative ∆T ≤ 20 CInsulation

Applied∆T (Tplacing 30 C)

∆T (Tplacing 20 C)



Remarks

During 7 days of insulation

Removing Insulation after 7days

Removing Insulation after 3days

No insulation applied

40 36

2 pieces of Plastic Sheet

38 30 29 32

2cm Water 30 24 28 32 1.8 cm Plywood

23 19 29 32 Surface condition let the structure to be close to Perfectly insulated condition “Main heat lost is through soil”

2cm Styrofoam

23 19 29 32

Perfectly insulated

23 19

60% GGBFS. 5%MS, 35%OPCTotal CM = 490 KgStructure = FoundationThickness = 3 mWork Plan for 7 daysAggregate Type: Limestone

Project Specification:Tmax = 75 C∆T ≤ 20 C

CIRIA C660: ∆T ≤ 35 C

Tmax = 82 at Tplacing 30.

Tmax = 72 at Tplacing 20 C.

Effect of Wind Speed. (Typical Wind Speed in Saudi Arabia )

Dammam

Riyadh

Jeddah

Effect of Wind Speed. (Raft Foundation)Tplacing = 30 C

Work Plan: Uninsulated Surface

OPC mix CM = 500 kg.

Ambient (45 – 30)

Wind Speed ∆T (3m)

∆T (2m)

∆T (1m)

Tmax (3m)

Tmax (2m)

Tmax (1m)

3 m/s (11 km/h) 55 48.7 34.7 100 96.5 86.7

6 m/s (22 km/h) 59.3 53.8 40 100 96.5 86.3

9 m/s (33 km/h) 61.5 56.2 42.7 100 96.5 86

12 m/s (44 km/h) 61.8 57.8 44 100 96.5 85.6

15 m/s (55 km/h) 63.5 59.1 45 100 96.5 85.6

(0 m/s) 39 31.5 27.5 100 96.5 88.5

Effect of Wind Speed. (Thick Wall)Tplacing = 30 COPC mix CM = 500 kg.Ambient (45 – 30)


∆T (1m)

∆T (0.5m)

Tmax (2m)

Tmax (1m)

Tmax (0.5m)

3 m/s (11 km/h) 23.6 14.5 7.4 98.4 93 866 m/s (22 km/h) 24.8 15.3 7.6 98.4 93 85.59 m/s (33 km/h) 25.2 15.4 7.8 98.4 92.9 85.312 m/s (44 km/h) 25.4 15.6 8 98.4 92.9 85.115 m/s (55 km/h) 25.4 15.6 8 98.4 92.9 85.1 (0 m/s) 19.5 11.3 5 98.5 93.8 87.6

Plywood Formwork


∆T (1m)

∆T (0.5m)

Tmax (2m)

Tmax (1m)

Tmax (0.5m)

3 m/s (11 km/h) 49 34.8 25.1 97.6 89.8 79.26 m/s (22 km/h) 54.6 39 31 97.4 89.2 79.29 m/s (33 km/h) 57.4 41.5 34.2 97.4 89 7912 m/s (44 km/h) 59.2 43.6 36.1 97.1 88.9 78.715 m/s (55 km/h) 60 44.6 37.2 97.1 88.5 78.7 (0 m/s) 33.1 21.6 11.8 97.8 91.5 82

SteelFormwork

Effect of Fly AshWind Speed Tmax ∆T Mi Mp MxRate Q28 Q90

Control 89 32 12.3 17.2 15.2 300 305

20%FA 83 30 13.4 19 11.5 266 270

30% FA 78 28 16.3 23.1 9.2 245 262

40% FA 74 25 21.5 30.5 7.7 220 229

50% FA 70 23 32.4 39.5 6 205 217

Effect of GGBFSWind Speed Tmax ∆T Mi Mp MxRate Q28 Q90

Control 89 32 12.3 17.2 17.2 300 305

40%GGBFS 85.5 32.8 16.1 20.6 10.8 279 285

50%GGBFS 80 29.3 10.4 14.8 8.7 283 293

60%GGBFS 77 27 7.5 14.6 7.5 234 237

70%GGBFS 75 26 12.6 17.9 4.8 242 251

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Engineering

Heat of Hydration in Mass Concrete