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Slag Uses:: Blast Furnace Slag

 

Beaver Valley’s blast furnace slag products excel over conventional aggregates in most road base and paving applications.  Because of how it was formed, it offers the following advantages:

Less effort to compact

Stable interlocking of granules and particles

Higher yield

High product purity

 

To compact a road base using a slag product will only require 50% of the effort that a typical aggregate would need.  A vibratory compactor will quickly work the surface into nearly 100% compaction in only a fraction of the time.

As an added benefit, because of the way slag interlocks, the surface remains planar and sound even under a heavy load.  For example, if a vehicle is driven over a compacted limestone road base, the surface would indent and swell around a tire’s surface.  In direct and vivid contrast, the slag surface remains undisturbed and sound.  The higher angle of repose, or the steepness of a natural stockpile, for slag further testifies to the inherent stability of the interlocking granules.

There is also a yield savings when you use slag, because less slag is required for a given job than conventional aggregates.  This is because slag was formed in the blistering hot temperatures of a blast furnace, under molten conditions, and pores or vesicles were formed as the slag cooled and gases were being released into the atmosphere.  This is why when you look at a piece of slag up close, it is literally riddled with holes.  The percent porosity is the fraction of volume that a piece of slag has that is taken up by these holes.  Since slag has similar strength and soundness characteristics that natural stone has, but a large volume percentage is taken up with air (the pores, or holes), a ton of slag can be used further than a ton of stone.  This is simply because a ton of slag takes up more space.  There is also a further freight savings, because more volume of slag can be placed on every truckload of slag going to the job site.

Click here to use an interactive spreadsheet analysis that demonstrates the cost savings of using Beaver Valley Slag.

The blistering high blast furnace temperatures also created an additional benefit: high product purity.  Impurities, such as dirt and clay, which are typically found in naturally occurring limestone are nonexistent in blast furnace slags.  The 2700 degree furnace, which literally melts rock, chemically recombines any impurities into slag’s molecular structure.  This structure is chemically uniform, and displays strong abrasion resistance because of its high purity. 

 
 

 

PRODUCTS

Beaver Valley Slag manufactures the following Penn D.O.T. certified products for roadbase and paving applications:

 

QUALITY CONTROL

2A Product Sieve Analysis (Adobe Acrobat® PDF)

57 Product Sieve Analysis (Adobe Acrobat® PDF)

8 Product Sieve Analysis (Adobe Acrobat® PDF)

2A Proctor Sample Analysis (Adobe Acrobat® PDF)

Blast Furnace Slag Weights & Densities (Adobe Acrobat® PDF)

TCLP Analysis (Adobe Acrobat® PDF)

Beaver Valley Slag must meet, or exceed, the stringent requirements established by Penn D.O.T. to maintain their certification of its washed and unwashed slag products.  The established systems are critical to assure to our customers that our products meet the gradation requirements, are chemically inert, and that they have low abrasion losses.  We can also work with customers to establishing QA/QC procedures for any requirements that they might have, such as chemical composition.

Three examples of test methods that Beaver Valley Slag must comply with are the L.A. Abrasion test, the Sulfate Soundness test, and the particle size analysis (gradation test).

The requirements for sampling and testing are established by Penn D.O.T.  Source verification samples are taken for every 5000 tons (or monthly) shipped to state jobs.  Field verification samples are taken at state certified jobs.  Requalification samples are taken biannually, at a minimum, for Beaver Valley Slag to maintain its certification.  A quality control plan is submitted annually for approval to the District Materials Engineer.  Any deviation from this plan or failure to meet specifications can result in the suspension or removal from Penn D.O.T.’s approved list.  Stockpiles and testing records are further checked by Penn D.O.T. inspectors.

The first test is used by ASTM, Penn D.O.T. and AASHTO to measure the aggregates susceptibility to breakdown.  A sample is tumbled for 500 revolutions inside a steel drum with six to twelve 15 ounce steel balls.  The rotating drum lifts the slag aggregate and smashes it between the tumbling steel balls.  The test method runs the slag material through a sieve screen and measures the percent broken down into fine particles.  Beaver Valley Slag products consistently beat the Penn D.O.T. requirement of 45% abrasion loss.  A typical round of 10 Beaver Valley Slag samples yields a 28% abrasion loss.

The second test is the Sodium Sulfate Soundness Test.  This test is used to measure the aggregates vulnerability to freezing and thawing degradation.  Water absorbed into the particles can freeze, causing an increase in volume which can breakdown aggregates.  In this method, a sample is immersed in a salt solution for 16 to 18 hours and dried.  Five cycles of this imitates five freezing and thawing cycles.  The salt crystallizes inside the particles exerting forces that cause a breakdown of the aggregate.  The sample is then sieved to determine the percent degradation.  Beaver Valley Slag products consistently beat the Penn D.O.T. requirement of 10% breakdown.  A typical round of 10 Beaver Valley Slag samples yields a 1.36% breakdown.

The third test checks the size distribution of the slag aggregates using sieve screens.  A dry sample is run through a mechanical shaker containing a series of progressively smaller screens.  After shaking, the amount of material retained on each screen is weighed to determine the percent passing to the next larger screen size.  Each material must be within PennDOT's gradation specifications.  Beaver Valley Slag’s products are sampled and tested by Penn D.O.T. certified aggregate technician before being put into approved stockpiles.  Beaver Valley Slag meets these requirements about 98% of the time, where the nonconforming material is stockpiled separately.

Unfortunately, slag has gotten an undeserved "bad reputation" for expanding in place.  Stories of "brand new parking lots cracking because of the sub-base expanding" have unfortunately substantiated this further.  However, Beaver Valley Slag's, both Blast Furnace and Steel, display no expansion characteristics.  They can be used with complete peace of mind in any sub-base applications.  Click here to read more about Slag Expansion... (Adobe Acrobat® PDF)

More information regarding:

Blast Furnace Slag Chemistry (Adobe Acrobat® PDF)

 

Home Up Product Specs
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6010 Woodlawn Road * Aliquippa, PA  15001 * Phone: 724-375-6170 ext# 15