“GREEN”Concrete TechnologyKatherine Chevrier

Concrete Mix Designs

3Presentation name or chapter

Concrete Mix Designs

Date |

You don’t have to be a Mad Professor!!!

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What is Concrete?

Components Concrete is a composite construction

material, composed of cement, SCMs (fly ash, silica, slag), aggregate (coarse and fine), water and chemical admixtures

The Cementitious portion combined with water and admixtures is considered the paste which acts to bind the aggregates together as it hardens

Aggregates provide the skeleton which gives the concrete volume stability

Hardening process by hydration Chemical reaction with water The hardening of the paste is referred

to the Hydration Reaction

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Concrete Fundamentals – Ingredient Blending

The % of ingredients blended within the design impacts the performance of the concrete and its intended use.

• Cementitous = cement + scm

• Grout / Paste = cementitous + water

+ admix• Mortar = grout + sand

• Concrete = mortar + gravel

Do not confuse the terms :

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Concrete Design Fundamentals

Crack Resistance Horizontal Application (SOG) Large sized CA (40mm/20mm) High amount of CA in design 100% fracture or high amount of fracture in CA blend Lower amount of %SCM replacement

Smooth Finish Vertical Application (Walls) Smaller sized CA (14mm) Lower amount of CA in design Round CA or round/fracture blend (30%) Higher amount of %SCM replacement

Special Density Concrete (Thermal conductivity/Radiation shielding) Normal weight concrete 2200 to 2400kg/m3 Lightweight concrete as low as 240kg/m3

(cork/pumice/beads) High Density Concrete up to 6000kg/m3 (magnetite/iron)

The right design for the right application

High Mpa Mixes (high rise) Smaller sized CA Low amount of CA in design Round/fracture blend High amount of %SCM replacement Low W/C ratio / HRWR Slow Strength Gain / hydration stabilizer

Tower Boom Pump Mixes Smaller sized CA (14mm) Lower amount of CA in design Round CA or low fracture blend (20%) Higher amount of %SCM replacement

SCC High SCM High amount of HRWR

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Concrete Design Fundamentals Green Designs

So How Do We Make Grey…

GREEN???

Cement and Cementing Materials – Better Environmental Options

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CementManufacturing

Clinker

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CementTypes of Cement Defined by CSA A3000

Type GU General Use

Type GuL Portland Limestone

Type HE High Early Strength

Type MS Mod sulphate resistance

Type HS High sulphate resistance

Type MH Moderate Heat of Hydration

Type LH Low Heat of Hydration

GU• Up to 5% interground

limestone

GUL or PLC• 6 to15% interground

limestone• 10% less C02 emissions

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Supplementary Cementing MaterialsUses in Concrete for Greener Options

Not “The Devil” if Used Properly

•At the RIGHT Dose•In the RIGHT Design •For the RIGHT Application

SCM

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Supplementary Cementing MaterialsEffects on concrete

• Fly ash, slag, silica fume are materials that when used in conjunction with Portland cement contribute to the hardened concrete through hydraulic or pozzolanic activity.

• Pozzolanic activity is when a material reacts with the calcium hydroxide released by the hydration of portland cement to contribute to the concretes performance and durability

• Bi – products of industry manufacturing• Coal – power plants• Iron ore - iron• Silicon

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Supplementary Cementing Materials Improved Placing/Workability

Less Bleeding Better pumping

Lower heat of hydration Lower temperature differentials

Improved permeability

Reduced CO2 emissions Less cement required

Improved Strength Gain Allows lower water to cement ratio Reaction with cement hydration

Crack control Stronger/resistant pores in surface

paste

Reduced landfill waste Reusing an industrial by

product

Reduced CO2 emissions Less cement required

Slower set times increased working hours premature surface drying can occur in

dry or windy weather tendency to finish too soon which can

cause delamination It is important not to seal the surface to

allow for delayed bleeding

Slower strength gain Slow down production Increase stripping times cement mixes

Inconsistencies in products Changes in carbon content can create

fluctuations in air contents

Water & AggregatesReduce Reuse Recycle

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Recycled Water – Non Potable – Grey Water

Settling Pond Wash water moves through a series of ponds

settling out solids/contaminates Water from the final pond is reused in

concrete at a replacement % of potable water Settlement slurry must be pumped, removed

and disposed of

Recyclers - Enviroports Wash water is deposited into an agitated tank,

aggregate is augured out and reused (e.g..

CDF mixes)

Water is then deposited through agitated

holding tanks, SG’s are read and displayed on

batch panel, water is reused in concrete at a

replacement % of potable water

Water must be continuously used to keep

SG’s down so it is safe to use in the

concrete . Expensive and high maintenance

Filter and Reuse – Recycle all Material = Reduce Intake

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Recycled Water – Non Potable – Grey WaterControl and Testing

CSA A23.1-14 4.2.2.4

“Water of unknown quality, including treated wash water and slurry water, shall not be used in concrete unless it produces 28 d concrete strengths equal to at least 90% of a control mixture.

The control mixture shall be produced using the same materials, proportions, and a known acceptable water.

The mixing water in question shall be assessed on a semi-annual basis or more frequently if any change in water quality is suspected.

The mixture used to assess the mix water shall be designed for a strength of 25 Mpa or greater at 28 d, and utilize a representative sample of the water in question”

1 1.05 1.1 1.15 1.20

0.05

0.1

0.15

0.2

0.25

0.3

0.35

f(x) = 1.56847759559 x − 1.57014014489R² = 0.968808503576898

%TSS vs SG lab

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Recycled Aggregate in BC ConcreteThe Future – Captains Log October 22 Year 2015…..

We are not there yet Currently working on testing and

trialing Getting recycled aggregate

usage acceptable in standards and specifications

Recycling Aggregate from demolished concrete structures Concrete is crushed, screened,

tested Recycled aggregate is then

reused in concrete products at a replacement % of virgin material

To make progressYou need to push progress

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Green ConcreteAn Industry Effort

Today’s modern concrete is a lot different than yesterdays mud

Concrete has changed to make bigger structures, longer bridges, higher buildings

Concrete can now achieve great strengths, get stronger faster, flow farther and place easier through the tightest steel and at any densityConcrete can replicate any

medium in appearance and can create the most wondrous structures

Concrete has changed to allow us to adapt in a new civilization, to house and transport our greater numbers, to make our lives easier and to surround us in beauty

We collectively have accepted the difficulties of modern chemical concrete to suit our needs and convenience when needed

Now lets collectively accept and work together as an industry to produce and use more “GREEN” concrete to suit our environment

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The EndThank You

So Put A Little

In Your Grey

GREEN