Steel Slag is a byproduct of the steelmaking process and is classied as a non-hazardous waste.* It is generated at a rate of 10-20% of the overall steel output. A signicant porDon of steel slag is unused and its disposal poses economic and environmental concerns due to its massive volume. ReuDlizaDon of steel slag conserves landll site and promotes sustainable development.

NSL Chemicals Ltd. started the research on the reuDlizaDon of steel slag in collaboraDon with local research insDtutes in 1991. The use of steel slag as pavement aggregate material was approved in Singapore in 1993. Since then, NSL Chemicals has been processing steel slag in Singapore and achieved a 100% recycling rate.

*D. Lewis. IRON and STEEL SLAG A NON-HAZARD. Na9onal Slag Associa9on. MF 194-5. December 14, 1980.

INTRODUCTION

THE NUMBERS:

More than 1 million tons of steel slag has been paved on Singapore roads over the last 15 years.

NSL Chemicals prac9ce on steel slag reu9liza9on has been es9mated to save over 860,000 m3 of landll site in Singapore.

NSL Chemicals has achieved a 100% steel slag recycling rate in Singapore.

1

CONTACT US AT:

NSL CHEMICALS LTD 26 TANJONG KLING ROAD

SINGAPORE 628051

Phone: (+65) 6513 6900 Email: Sales@nslchemicals.com.sg http://www.nslchemicals.com.sg/

NSL Chemicals Ltd.

2012

Steel slag in road making The research on the use of steel slag in exible pavement was rst conducted in the year 1991. Using steel slag for road surfacing materials has been found to be extremely advantageous. It oers the following benets:

Increases skid resistance Improves ruRng resistance Displays high resistance to moisture damage, less

stripping. Promotes sustainable development

All of these lead to increased lifespan of the pavement and safer road condiDons, as well as the conservaDon of natural resources. Due to steel slags special properDes, it has been specied for areas with adverse trac condiDons such as road juncDons and slip roads from the expressways.

Some of these superior properDes can be seen from the table below:

NSL CHEMICALS LTD 26 TANJONG KLING ROAD SINGAPORE 628051 http://www.nslchemicals.com.sg/

Parameter

Typical Values of Asphalt Mix Remarks

Steel Slag Granite

Marshall Stability (kN)

20.6 11.0 Superior performance

Marshall Flow (Unit) 3.61 3.85 Within range

Void in Mix (%) 4.98 4 Within range

Wheeltracking (mm/h)

3.7 10 Less deformation & wear

Repeated Load Indirect Tensile Test (Mpa)

3071 2607 Superior performance

Life cycle assessment of steel slag and granite aggregates

ENVIRONMENTAL BENEFITS

2

0

0.01

0.02

0.03

0.04

0.05

Steel Slag Granite

kgC

O2e

Transportation

Electricity

Diesel

Explosives

Carbon footprint of steel slag and granite aggregates

Steel slag oers excepDonal environmental benets in terms of:

ConservaDon of natural resources ReducDon of waste by recycling steelmaking byproducts ReducDon of carbon footprint in comparison with granite

when used as a construcDon material in Singapore

In addiDon, steel slag is considered an environmentally benign material based on leaching procedure tests.

NSL CHEMICALS LTD 26 TANJONG KLING ROAD SINGAPORE 628051 http://www.nslchemicals.com.sg/

Where does steel slag come from?

TREATED STEEL SCRAP

Electric Arc

MELTING

SCRAP CHARGING BUCKET

SLAG TAPPING

Slag Pit

Slag

Steel slag is a non-metallic ceramic material formed during steelmaking.

It is generated from the reacDon between the uxing agents and the inorganic non-metallic components in the steel scrap.

Steel slag oats on top of the molten steel.

The hot slag is collected and processed into steel slag aggregates.

In-house treatment methods ensure that the aggregate is suitable to be used as construcDon material.

STEEL SLAG PROCESSING

3

Steel slag properties

Steel slag is not only a renewable resource, but also oers superior mechanical performance as an aggregate material. The benets of steel slag stem from its special morphological, physical and chemical/mineralogical properDes:

High mechanical strength Good pavement durability

High angularity Good aggregate interlocking, high ruRng resistance

Rough surface texture High polished stone value, high pavement skid resistance

Hydrophobic/basic surface chemistry Good bonding with asphalt binder, less stripping, be[er

resistance to moisture damage

NSL CHEMICALS LTD 26 TANJONG KLING ROAD SINGAPORE 628051 http://www.nslchemicals.com.sg/

Chemical & physical properties of Steel Slag

Typical chemical composi.ons of EAF steel slag & granite

4

STEEL SLAG PROPERTIES

Component Steel Slag (wt%) Granite Rock (wt%)

SiO2 CaO FeO MgO MnO Al2O3

Jurong West St 51 Traffic Junction

Boon Lay Dr Traffic Junction

Corporation Road

AYE Jurong Townhall exit Aye Rajah Expressway

St Andrews Road

STEEL SLAG ON SINGAPORE ROADS

Roads that Use Steel Slag Aggregates in Singapore

5

Boon Lay Way Traffic Junction

LIFE OF STEEL SLAG

The Life of steel slag

NSL CHEMICALS LTD 26 TANJONG KLING ROAD SINGAPORE 628051 http://www.nslchemicals.com.sg/ 6