steel slag for road pavement
DESCRIPTION
Steel slag is an environmental material to replace granite as asphalt pavement aggregate and provides excellent pavement quality.TRANSCRIPT
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OUTLINE
1. What is Steel Slag?
2. Recycling of Steel Slag
3. Properties of Steel Slag
4. Sustainable Development
5. Steel Slag Road Pavement
6. Conclusions 2
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1. WHAT IS STEEL SLAG ?
Steel slag is a co-product from the steelmaking process.
There are two types of steel slag:
EAF slag (from mini mills; Singapore)
BOS slag (from integrated mills)
Steel slag is a ceramic material formed from the reaction
of flux such as calcium oxide with the inorganic non-
metallic components present in the steel scrap.
The chemical composition of steel slag depends on the
quality of the feed material, the steelmaking process and
the grade of steel produced. 3
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1. WHAT IS STEEL SLAG ?
TREATED STEEL SCRAP
ElectricArc
MELTING
SCRAP CHARGING BUCKET SLAG TAPPING
Slag Pit
Slag
Steel slag floats on top of the molten steel.
The hot slag is processed into steel slag aggregates.
In-house treatment method ensures that the aggregate is
suitable for use as road construction material.
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Flux
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2. RECYCLING OF STEEL SLAG
In many countries, steel slag is typically landfilled or dumped onsite. Reuse of steel slag conserves landfill site and promotessustainable development.
NSL Chemicals, together with the local universities have jointlyconducted research projects on the use of steel slag since 1991.
In 1993, a successful public road trial conducted with the LandTransport Authority of Singapore (Public Works Dept.) led to theapproval of steel slag for use on Singapore roads.
Over the last 19 years, more than 1.3 million tons of steel slag hasbeen paved on Singapore roads.
NSL Chemicals practice on steel slag reutilization has beenestimated to save over 520,000 m3 of landfill site in Singapore.
Now 100% of the steel slag generated in Singapore is recycled intoroad-making materials. 5
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3. PROPERTIES OF STEEL SLAG Typical comparative chemical compositions of steel slag
and granite:
Steel slag contains significantly higher calcium and ferrouscontent compared to granite rock.
Granite rock contains high silica and alumina content.
Steel slag is hydrophobic in nature (better adhesion withbitumen) while natural rock is generally hydrophilic (higheraffinity to water than to organic materials, e.g. bitumen).
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Components Steel Slag (wt%) Granite Rock (wt%)
SiO2CaOFeOMgOMnOAl2O3
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Properties Granite Slag Remarks
pH 7 11 Steel slag is alkaline and bonds better with bitumen.
Polished Stone Value 49 60-61 Steel slag has better resistance to skidding.
LA Abrasion Value (%) 35 20-25 Steel slag has less abrasion loss.
Aggregate Impact Value (%)
21-31 14 Steel slag is harder than granite.
Magnesium SulphateSoundness (%)
2.1 0.6-2.4 Steel slag is more resistant to freeze-thaw weathering.
Flakiness Index 22 3-16 Lower flakiness index indicates higher structural stability.
3. PROPERTIES OF STEEL SLAG
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Typical comparative physical properties of steel slag and
granite aggregates:
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3. PROPERTIES OF STEEL SLAG
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Granite Steel Slag
Comparative physical properties of steel slag and granites:
The good resistance to stripping and high Polished Stone Valueexhibited by the steel slag aggregates show that steel slag issuperior to natural granite as a road surfacing material.
The superior adhesion between steel slag and bitumen reducestypical moisture damage problems affecting granite pavement.
Steel slag pavement performs better in wet climate. Suchpavement surfaces tend to stay intact over longer period of time.
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Road pavement mixes with steel slag formulation have
better rut resistance and mechanical stability.
This indicates a more durable wearing course for the
road.
Parameter Comparative Pavement
Mixes
LTA
Specs
Remarks
Steel slag Granite
Marshall Stability, kN
20.6 11.0 9 kN Steel slag mix displays better Marshall stability.
Flow, mm 3.60 3.85 2 4 Within specified range.
Void in Mix 4.93% 4.00 % 3 5% Within specified range.
Wheeltrack(mm/hr) 60oC
3.68 9.90 Steel slag mix has less deformation and wear.
3. PROPERTIES OF STEEL SLAG
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4. SUSTAINABILTY
Environmentally friendly
Steel slag is classified as a non-hazardous waste.
Leaching test result shows compliance with
environmental regulation.
Element Steel Slag (ppm) Limit (ppm) Element Steel Slag (ppm) Limit (ppm)
As
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4. SUSTAINABILITY
The use of steel slag
Reduces the reliance on natural resources.
Reutilizes waste material and conserves land.
Helps to reduce greenhouse gases emission.
0.00
0.01
0.02
0.03
0.04
0.05
Steel Slag Granite
k
g
C
O
2
e
Transportation
Electricity
Diesel
Explosives
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Life Cycle Analysis of Steel Slag and
Granite Aggregate
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5. STEEL SLAG ROAD PAVEMENT
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6. CONCLUSIONS
Steel slag aggregate can be beneficially used as a road
surfacing material when it is properly treated, processed
and engineered for the application.
The physical and chemical characteristics are superior to
granite in road pavement application, particularly in its
Marshall stability and resistance to rutting, skid, and
bitumen stripping.
Use of steel slag aggregates mitigates the reliance on
quarry material extraction and assists in sustainable
development.
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not use, divulge or reproduce the said information in any way without a written consent from NSL Chemicals Ltd.
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Thank You!
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The contents of these slides are private, confidential and proprietary to NSL Chemicals Ltd. The recipient / viewer of these slides shall
not use, divulge or reproduce the said information in any way without a written consent from NSL Chemicals Ltd.
NSL Chemicals Ltd
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Phone: (+65) 6513 6900
Email: [email protected]
Website: http://www.nslchemicals.com.sg/