Army Sustainability Workshopy y p

PRESENTED  BY  LEBANON  GREEN  BUILDING  COUNCIL(LGBC)

NOVEMBER  12  – 13  – 19 DECEMBER  1  &  8  

PresenterMarcel El‐KhouryMarcel El KhouryChemist (MS)

TITLE

S t i bl “G ” C tSustainable “Green” Concrete

INDEX Concrete Composition Concrete Composition Cement Production Process & Composition CO2 emissions in Cement Production Concept of “Green” Cement Conventional Vs Regenerated Concreteg High Strength and High Performance Concrete Mechanism for Concrete Admixture for the use in HPC Sustainable & Durable Concrete Comparative Conclusion

Concrete CompositionComponent Characteristic

% By VolumeComponent Characteristic

Cement Responsible for the strength

Forms together with the cement the

18%

Water Forms together with the cement the cement stone. Affects the durability

Aggregate Fill out the cement matrix and determine the kind of the concrete

69% 9%

2%

AdditivesDepending on the type: used for the improvement of the concrete characteristics or just as filler

Admixture Affects fresh and hardened concrete characteristics

0.5%1.5%

Aggregates Water Cement characteristicsAggregates Water CementAdditives Admixture Air

Cement production process & Composition

CO2 emissions in Cement production process

E h 1 T f OPC ( d f 95% Cli k ) d Each 1 Ton of OPC (made of 95% Clinker) produces1.25 Tons of CO2 emissions (0.75 Tons from energyuse + 0.5 Tons from calcination limestone) =>Responsible of 8% of Global CO2 emissions.

The fact that Clinker causes the main CO emissions The fact that Clinker causes the main CO2 emissionsin Cement production leads that modifying Cementformulation is necessary to reduce CO2 emissions.This can be done by replacing clinker with secondarycementitious materials like limestone naturalcementitious materials like limestone, naturalpozzolanes, fly ash and slag. => Each 1% of reducedclinker content lowers the CO2 emissions by 0.008Tons CO2 by 1 Ton Cement production. (i.e. 1 Tonblended Cement with 80% Clinker content causes1.13 Tons CO2 emissions instead of 1.25 Tons.)

f “ ”Concept of “Green” CementBl d d C t h l CO i i b t t t Blended Cement has lower CO2 emissions, but testsshowed a significant drop in Compressive strengthcomparing to OPC.

Adding a Quality Improver (Strength Enhancer) Adding a Quality Improver (Strength Enhancer)additive to Cement Production will increase theStrength development.

Quality Improvers are as well Grinding Aids, theyQuality Improvers are as well Grinding Aids, theyhelp to increase productivity and minimize Carbonfootprints to the rate of 0.8 Tons CO2 per 1 TonCement.

f “ ”Concept of “Green” CementImproved Efficiency of Grinding Process Increase production volume Reduce Energy consumption Increase sales volume cement = benefit

Enhanced Cement Quality R li bl t th d l t Reliable strength development Higher amount of Clinker Replacements Adjust cement powder flowability Reduce risk of brown discolouration

Reduce CO2 Emission Less grinding energy Less impact of calcination & burning 

energy due to reduced clinker content

l dConventional Vs Regenerated ConcreteRegenerated Concrete is replacing normal aggregates by Regenerated Aggregates having similar grading size

However, High Performance Concrete could not be obtained with regenerated aggregates due to its highwater depend required; therefore other techniques should be applied for High Strength “Green” Concrete.water depend required; therefore other techniques should be applied for High Strength Green Concrete.

High Strength & High Performance ConcreteHigh Strength Concrete (HSC) includes cementitious materials with compressive strength as high as 200 Mpa.High Performance Concrete (HPC) includes other properties in addition to high strength, as for long‐termdurability, crack‐resistant, high‐ductility, etc..HPC is obtained when a low Water/Cement ratio could be applied in addition to an optimized mix design.Thus shall be obtained when using a HRWR superplasticizer such as:

high

Workability Early strength development

n Melaminesulphonates

Polycarboxylate

wat

er re

duct

ion e a esu p o ates

Naphthalenesulphonates

Lignosulphonates

low

h f dMechanism for Concrete admixturesLignosuphonates

Electrostatic inter particle repulsion Electrostatic inter particle repulsion Reduced surface tension Retarding the hydration process Liberated entrapped water Improved workability Water reduction up to 15%

Free waterEntrapped waterpp

Cement particlefloc Cement particlefloc

h f d Electrostatic inter particle repulsion

Mechanism for Concrete admixturesMelaminesulphonates and Naphthalenesulphonates Electrostatic inter particle repulsion Negative charged molecules attach to cement grains and repel each other Improved workability Water reduction up to 25%

Cement particle

h f dMechanism for Concrete admixturesPolycarboxylates Electrostatic inter particle repulsion Electrostatic inter particle repulsion Large molecules acting as a barrier between the cement particles- steric hindrance Dispersion of cement grains preventing formation of cement lumps Strongly improved workability Water reduction up to 40%

2L2L

bl & blCSHPore area S t i bl d D bl C t i bt i d b

Sustainable & Durable Concrete

antit

y

CSHlong-fibrously

CSHshort-fibrously

Pore area Sustainable and Durable Concrete is obtained byadding Micro Silica (Silica Fume) to Concrete mixtureas a cement replacement.

Micro Silica reacts with the forming Ca(OH)2 formedfrom Hydration Process between Cement and water

Qua

g y

Minutes HoursHydration time

Days

from Hydration Process between Cement and waterin order to form additional CSHCement + H2O ‐‐‐‐‐> CSH (Hydrate Calcium Silicate) + Ca(OH)2Ca(OH)2 + SiO2 ‐‐‐‐‐> CSH (additional Cement gel)

Hydration stage I stage II Hydration stage III

hardeningstiffening

lComparative ConclusionParameters Traditional

ConcreteConventional Concrete

Regenerated Concrete

High StrengthConcrete

High PerformanceSustainable ConcreteConcrete Concrete Concrete Concrete Sustainable Concrete

OPC 350 kg/m3 ‐ ‐ ‐ ‐Blended Cement ‐ 350 kg/m3 350 kg/m3 350 kg/m3 320 kg/m3

Micro Silica 30 kg/m3Micro Silica ‐ ‐ ‐ ‐ 30 kg/m3

Water 200  L/m3 160  L/m3 160  L/m3 125 L/m3 125 L/m3

Aggregates & sand

1800  kg/m3 1875  kg/m3 1000  kg/m3 2000  kg/m3 2000  kg/m3

Regenerated Aggregates

‐ ‐ 950  kg/m3 ‐ ‐

Admixture (2ndGeneration)

‐ 5 L/m3 5 L/m3 ‐ ‐

Ad i t (3rd 7 L/ 3 7 L/ 3Admixture (3rdGeneration)

‐ ‐ ‐ 7 L/m3 7 L/m3

lComparative ConclusionParameters Traditional

ConcreteConventional Concrete

Regenerated Concrete

High StrengthConcrete

High PerformanceSustainable ConcreteConcrete Concrete Concrete Concrete Sustainable Concrete

Initial Slump 150 mm 200 mm 200 mm 230 mm 230 mm

After 60 min 70 mm 160 mm 150 mm 200 mm 210 mm

Consistency &  Low Medium Medium High Very HighCohesiveness

Strength at 24 hours

N/A 6 MPa 5 MPa 14 MPa 13 MPa

Strength at 7 Days

17 MPa 25 MPa 24 MPa 30 MPa 32 MPaDays

Strength at 28 Days

25 MPa 33 MPa 32 MPa 42 MPa 52 MPa

RCP >3000 C ~ 2000 C ~ 2200 C ~ 1800 C ~1000 C

W t ti ht / V L L L M di Hi hWater tightness/ Durability

Very Low Low Low Medium High

Thank youPlease contact CEDRO at: Thank you T/F: +961‐1‐981944E: info@cedro‐undp.orgwww.cedro‐undp.orgBeirut, Maarad Street, Building 287B, 1st floor

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