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What is slurry seal?

The principal materials used to create slurry seal are aggregate, asphalt emulsion,

and filler, which are mixed together according to a laboratory's design-mix formula.Water is also added for workability.

Asphalt emulsions serve as a binder, holding the crushed aggregate together and

adhering the new slurry surfacing to the old surface over which it is being applied.

Various emulsions and aggregates are used to meet the conditions, specifications,and requirements of individual projects.

The aggregate must be clean, crushed, durable, properly graded, and uniform. Theasphalt emulsion is a three-part system consisting of asphalt, water, and emulsifier.

Fillers such as Portland cement, hydrated lime, or aluminum sulfate liquid are oftenused in small quantities as stabilizers or chemical modifiers.

History of Slurry

In the early 1930s, a coating consisting of a mixture of very fine aggregates, asphalt

binder, and water was laid out on a road in Germany. It proved to be a novelapproach, a new and promising technique in maintaining road surfaces, and marked

the beginning of slurry seal development.

Later in that decade, extensive worldwide experimentation begin in earnest. But it

was not until the 1960s, with the introduction of improved emulsifiers andcontinuous flow machines, that real interest was shown in the usage of slurry seal for

a wide variety of applications.

Continuing advancements in mixing methods, emulsions and machinery have made

slurry seal today's choice in providing highly durable, low cost paving and surfacemaintenance. As a treatment for everything from residential driveways to public

roads, highways, airport runways, parking lots, and a multitude of other pavedsurfaces, slurry seal is now used extensively throughout the world. Local, state, and

federal agencies including the military have a growing and ongoing commitmentto the use of slurry seal in their maintenance programs, attesting to its effectiveness

and economy.

How is Slurry Made?

Slurry is made in specially designed equipment, either truck-mounted or self-propelled. This equipment carries a quantity of unmixed materials which are blended

together in a continuous flow pugmill. The use of this technologically advanced

machinery insures a smooth, consistently uniform mixture.

Slurry is made quickly and accurately at the project site. Mixing and spreading areaccomplished in one continuous operation, with the surface being reopened to travel

within a few hours.

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How is Slurry Applied?

Slurry seal is applied to an existing pavement surface by means of a spreader boxlinked to the surface slurry-mixing unit. Slurry is introduced into the spreader box,

which then lays down the slurry coating as the mixer/spreader is driven forward.

The box is capable of spreading the slurry seal over the width of a traffic lane in asingle pass, and is constructed so that close contact with the existing surface is

maintained. This insures uniform application of the new coating on a variety ofconfigurations encompassing various crowd shapes, superelevated sections, and

shoulder slopes.

Trained operators continually monitor the automatic mixing procedure. Otherpersonnel clean the surface before slurry applications, barricade the street, inspectthe operation in progress for uniformity, clean metal utility covers after application,

and complete slurry seal spreading in any area inaccessible to the spreader box.

Types of Slurry

Emulsions of varying composition and setting times are mixed with any one of threegrades of aggregates to create slurry seal mixes for specific purposes.

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Aggregate types are I (fine), II (general), and III (coarse). Fine aggregate mixturesare used for maximum crack penetration and sealing in low-density/low-wear traffic

areas. Type II aggregates are the most commonly used and are widely employedwhere moderate-to-heavy traffic is found. They seal, correct moderate-to-severe

ravelling, oxidation and loss of matrix, and improve skid resistance. Type III correctssevere surface conditions preventing hydroplaning and providing skid resistance

under very heavy traffic loads.

A slurry seal for nearly any need or condition can be custom designed to satisfy the

most difficult requirements.

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Why Use Slurry Surfacing?

Pavement Performance Histograph

As shown below, slurry seal maintenance dramatically extends pavement life.

Although the serviceability of an untreated asphalt pavement is still adequate afterseveral years of use, pavement deterioration has already begun.

A slurry seal maintenance program undertaken before significant pavement

deterioration has begun is essential to proper pavement maintenance.

Preventive maintenance is more cost-effective than corrective maintenance.

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Advantages of Using Slurry

As the most versatile of any pavement surface treatment system, slurry seal is alsounique in its ability to deposit a durable bituminous mixture in accordance with the

demands of a variably textured surface - filling cracks and voids, sealing weather-tight, and providing color and texture delineation in a single pass.Low cost

Economical to install, highly cost-effective to use.Rapid usability

Easy, swift application of a new overlay makes slurry especially attractive forrehabilitating busy thoroughfares, parking lots, and airport runways. The new

surface is ready for use just hours after application.Preventing problems

Used over newly laid pavements, slurry seal will prevent surface distressessuch as the effects of weathering from occurring. Oxidation, loss of oils, loss

of matrix, and embrittlement of the mix are minimized. It also providesspecial durability and texture not available in the underlying mix.

Correcting problems

Existing distresses in older pavements surface cracking, ravelling, loss of

matrix, increased water and air permeability, and slipperiness due to flushingand aggregate polishing can be corrected through a slurry application.

Waterproofing is also achieved, preventing further deterioration. An all-weather, long-lasting surface is created that offers skid resistance and

improved handling characteristics for drivers.Aesthetic value

With one simple application, existing pavement receives a new wearing

surface of uniform black color and texture. Enhanced appearance meansincreased property value, marketing potential, and buyer acceptance.

Thoroughfares, shopping center parking lots, and other public or commercial

pavements treated with slurry seal become more attractive and eye-

appealing.Benefits of Pavement Maintenance

Even the best of surfaces are subject to the wear and tear caused by time, weather,

and traffic. No surface is permanent.

By undertaking a program of planned pavement maintenance, considerable savings

in rehabilitation costs may be achieved. Your pavement surface will remain sound,usable, and safe. Extensive downtime needed to repair deep cracks and potholes will

be reduced or eliminated.

The application of slurry seal will significantly extend the life of existing pavementsby protecting the under-surface from damage caused by water seepage. Improvedsurface performance is an added bonus.

A pavement maintenance program using slurry seal will not only help to protect yourpavement, it will help to protect your paving investment.