This document provides information about the use of fly ash to replace 35% of the cement in concrete for the construction of Africa's largest suspension bridge in Mozambique. It discusses the project organization between CRBC, GAUFF Engineering, and the owner EDMS. The document outlines the sustainability benefits of using fly ash, which produces fewer carbon emissions than cement. It also provides details on the concrete mix design, materials used, testing results showing the concrete meets durability and strength requirements. In summary, this document discusses the sustainability and technical aspects of using fly ash concrete for the large Maputo Bridge project in Mozambique.

1. CRBC in cooperation with GAUFF
USE OF FLY ASH FOR AFRICA´S LARGEST
SUSPENSION BRIDGE IN MOZAMBIQUE

2. Maputo Bridge and Link Roads Project
Authors:
 Dean Swanepoel1-dswanepoel@gauff.net
 Joern Seitz² -jseitz@gauff.net
 Bai Pengyu³-bpy9702@hotmail.com
1&2GAUFF Engineering, Maputo/Mozambique
Nuremberg/Germany
3CRBC China Road and Bridge Corporation, Beijing, China
09-11-2016 2

3. Maputo Bridge and Link Roads Project
SUSTAINABILITY
“In the future Civilization will be measured against
present humanities ability to sustainably
conceptualize, create and preserve”
L.J.L.Greene.
Aiming to balance social, environmental and economic factors are a major part
of the contractor’s international sustainability image, hence the choice for
substituting 35% of the cement with fly ash. Fly Ash, being a waste product of
electricity produced by the burning of coal, emissions are 2kg CO₂e/ton
compared to cement being 840kg CO₂e/ton
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4. Maputo Bridge and Link Roads Project
09-11-2016 4

5. Maputo Bridge and Link Roads Project
Content
• Introduction
• Project
• Concreting Requirements
• Equipment
• Aggregates
• Quantities of materials
• Durability testing results and concrete strength
• Acknowledgements
09-11-2016 5

6. The project Organisation: EDMS - CRBC - GAUFF
6
Representative of the Owner:
Empresa de Desenvolimento de MAPUTO SUL, E.P. (EDMS)
Owner / Client
Governo da Republica do Mocambique
09-11-2016
Contractor:
China Road and Bridge Corporation (CRBC)
Supervision / Design verification:
GAUFF Engineering, Germany

7. GAUFF ENGINEERING- GAUFF Maputo Staff
• German Consulting Company for Civil Engineering (Nuremberg)
• In excess of 40 years Engineering experience in Africa
• Bridge Staff of app. 15 Expat engineers and 15 Local Engineers and
technicians with administrative support staff.
• Expat Engineers from Russian, Poland, Germany, China, Portugal,
South Africa, Namibia and Zimbabwe compliment the Maputo team.
• Employ a Greek Structural consultancy for EN specification
comparison to Chinese norms.
29.01.2016 7

8. Maputo Bridge and Link Roads Project
Content
• Introduction
• Project
• Concreting Requirements
• Equipment
• Aggregates
• Quantities of materials
• Durability testing results and concrete strength
• Acknowledgements
09-11-2016 8

9. Maputo Bridge and Link Roads Project
29.01.2016 9

10. Maputo Bridge and Link Roads Project
Content
• Introduction
• Project
• Concreting Requirements
• Equipment
• Aggregates
• Quantities of materials
• Durability testing results and concrete strength
• Acknowledgements
09-11-2016 10

11. Concreting Requirements-SATCC Table 6306/1
Condition of exposure
VERY SEVERE
Concrete surfaces exposed to aggressive water, sea-water spray or a
saline atmosphere.
Description of member/surface to which the cover applies
Cast in situ piles, wet cast against casings.
Minimum cover (mm) 80
Class of concrete (MPa) 40
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12. Maputo Bridge and Link Roads Project
Content
• Introduction
• Project
• Concreting Requirements
• Equipment
• Aggregates
• Quantities of materials
• Durability testing results and concrete strength
• Acknowledgements
09-11-2016 12

13. 19-11-2016 13

14. Maputo Bridge and Link Roads Project
Content
• Introduction
• Project
• Concreting Requirements
• Equipment
• Aggregates
• Quantities of materials
• Durability testing results and concrete strength
• Acknowledgements
09-11-2016 14

15. Materials and List of quantities to date
1509-11-2016
15872 tons
79231 tons
107 362 m³
541 tons
79231 tons
29309 tons83956 tons
7700 m³

16. Cementatious Material-Cement
CEMENT
• Cement, type CEM II/ A-L 42.5 N, for the project is supplied by CM
(Cimentos de Mozambique) located in Matola city outside Maputo.
• CEM II/A-L 42.5 N cement is a Portland Limestone Cement
comprising between 80-94 % clinker and between 6-20%
Limestone. It has the ability to produce cement strengths between
42.5 MPa and 62.5 MPa.
• The average compressive strength of the cement tested in the site
laboratory of CRBC in Katembe at 28 days averages 51.5 MPa.
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17. Cementatious Material – Fly Ash
Fly Ash
• Class “S” Fly Ash from South Africa is used extensively on the
Maputo Bridge project to promote Pozzolanic activity with the
cement.
• FA supplied from both suppliers conforms to the SANS 50450-
1:2011 requirements for concrete.
• The advantage of the addition of FA in the range of 25 % – 40 % of
the total Cementatious materials is as follows.
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18. Cementatious Material – Fly Ash
In fresh concrete:
• Improves workability and reduces water requirement for a given
slump
• Slightly retards setting
• Improves compaction and retains workability
• Significant increase in pumpability
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19. Cementatious Material – Fly Ash
In hardened concrete generally:
• Slightly reduces rate of strength development
• Reduction in shrinkage due to lower water demand
• Refines pore structure and reduces permeability
• Improves sulphate resistance
• Significantly reduces the risk of thermal cracking
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20. Cementatious Material – Fly Ash
In hardened concrete:
• Increases later age strength e.g. at 90 days
• Reduces the rate of chloride diffusion through concrete
• Prevents or retards alkali-silica reaction
• Reduces rate of heat generation caused by cementing reactions by
up to 20%
• Enhances the reinforcements resistance to chloride attack
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21. Typical results of fly ash (FA) received from supplier
Chemical Requirements
Tested
percentages
Specification
SANS 50450-1:2011
Loss of ignition 1.1 Max. 5.0 % by mass
Chloride content (Clˉ) 0.0 Max. 0.10 % by mass
Sulfuric anhydride (SO₃) 1.0 Max. 3.0 % by mass
Free calcium oxide ** 1.2 % Max. 2.5 % ** or 1.0 % by mass
Calcium oxide 6.4 % Max. 10.0 % by mass
Reactive calcium oxide Not required Calcium oxide <10 %
Reactive silicon dioxide Not required No co-combustion
Si. dioxide, Al. oxide and Ir. oxide Not required No co-combustion
Na₂O (equivalent) Not required No co-combustion
Magnesium oxide (MgO) Not required No co-combustion
Soluble phosphate (P₂O₅) Not required No co-combustion
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Physical Requirements Test results
Specification
SANS 50450-1:2011
Fineness retained on the 45 micron
sieve
8.0 % Max. 12.0 % by mass
Activity index 82 % Min. 75 % @ 28 days
Activity index 103 % Min. 85 % @ 90 days
Soundness, expansion** 1 mm Max. of 10 mm
Particle density 2300 kg/m3 Max. +/-200 kg/m³ of declaration
Initial setting times Not required No co-combustion
Water requirement 95 % Max. 95 % by mass of control

22. Chemical admixtures
The benefits of using a Superplasticizer lie in the improvement of
concrete properties to suit specific applications.
• Increased fluidity enabling the concrete to penetrate through
congested reinforcing (PRESENTATION SEITZ SESSION 11 No. 3)
• Excellent workability required for self-compacting and self-leveling
concretes for piles
• Reducing the W/C ratio to give high strength
• Improve durability
• Reduce shrinkage
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23. Maputo Bridge and Link Roads Project
Content
• Introduction
• Project
• Concreting Requirements
• Equipment
• Aggregates
• Quantities of materials
• Durability testing results and concrete strength
• Acknowledgements
09-11-2016 23

24. Durability Indexes
Oxygen permeability Index results
Sample ID k value(m/s) OPI
A 8,631E-12 11,06
B 2,427E-12 11,611
C 3,758E-12 11,42
D 4,079E-12 11,391
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25. Durability Indexes
Water Sorptivity index test results
Sample ID Sorptivity (mm/√hr) Porosity (%)
A 3,36 6,93
B 2,99 6,68
C 5,26 6,35
D 4,93 6,63
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26. Durability Indexes
Chloride conductivity index test results
Sample ID Conductivity (mS/cm)
A 0,22
B 0,14
C 0,16
D 0,19
• Values of 0.8 are typically obtained from samples having a w/b ratio
of 0.4
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27. Concrete strength graph
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50.4
57.1
43.7
40.0
45.0
50.0
55.0
60.0
65.0
572 580 588 596 604 612 620 628 636 644 652 660 668 676 684 692 700 708 716 724 732 740 748 756
Compressivestrength[Mpa]
Number of test results
Month August to September 2016
Katembe site
C40
28 days compressive strength test results
Average of 28 days compressive strength sample tests (3 cubes) [Mpa]
Average 28 days compressive strength test results µ [Mpa]
µ+2 ơ [Mpa]
µ-2 ơ [Mpa]

28. Concrete construction at its best.
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28

29. 15-11-2016 29
Concreting of piles

30. Maputo Bridge and Link Roads Project
Content
• Introduction
• Project
• Concreting Requirements
• Equipment
• Aggregates
• Quantities of materials
• Durability testing results and concrete strength
• Acknowledgements
09-11-2016 30

31. 15-11-2016 31
Maputo Bridge and Link Roads Project
Dankie
及物动词
Danke
Obrigado
Mercie beaucoup
Спасибо
Dziękuję
Ευχαριστούμε
Thank You