ASPHALT SLURRY SEAL COAT
PART 1 GENERAL
1.1SECTION INCLUDES
A.Placing a mixture of fine graded aggregate, mineral filler, emulsified
asphalt, and water.
1.2RELATED SECTIONS Not Used
1.3REFERENCES
A.AASHTO M 17: Mineral Filler for Bituminous Paving Mixtures
B.AASHTO M 29: Fine Aggregate for Asphalt Mixtures
C.AASHTO M 208: Cationic Emulsified Asphalt
D.AASHTO T 11: Materials Finer than 75-µm (No. 200) Sieve in Mineral
Aggregates by Washing
E.AASHTO T 27: Sieve Analysis of Fine and Coarse Aggregates
F.AASHTO T 96: Resistance to Degradation of Small-Size Coarse
Aggregate by Abrasion and Impact in the Los Angeles Machine
G.AASHTO T 104: Soundness of Aggregate by Use of Sodium Sulfate or
Magnesium Sulfate
H.AASHTO T 176: Plastic Fines in Graded Aggregates and Soils by Use of
the Sand Equivalent Test
I.AASHTO T 278: Surface Frictional Properties Using the British Pendulum
Tester
J.AASHTO T 279: Accelerated Polishing of Aggregates Using the British
Wheel
K.International Slurry Seal Association (ISSA) A105 Guidelines
L.UDOT Quality Management Plan
Asphalt Slurry Seal Coat
M.UDOT Minimum Sampling and Testing Requirements
1.4DEFINITIONS Not Used
1.5SUBMITTALS
A.Mix Design and test results for review.
1.Meet the requirements of this Section, Article 2.7.
2.Include target gradation for combined aggregate and mineral filler.
3.Additive list and dosage rates from mix design.
B.Test reports for aggregate for information.
1.Meet the requirements of this Section, Article 2.2.
C.Manufacturer’s Certificate of Compliance for Mineral Filler for information.
D.Verification that the emulsified asphalt supplier adheres to UDOT Quality
Management Plan 508 Asphalt Emulsion for information.
1.Certificate of analysis/compliance from the manufacturer for each
shipment.
1.6ACCEPTANCE
A.Sampling and testing of material is according to UDOT Minimum Sampling
and Testing Requirements.
B.Meet the Target Tolerance of Table 1.
PART 2 PRODUCTS
2.1EMULSIFIED ASPHALT
A.Use a cationic emulsified asphalt grade CQS-1h according to AASHTO M
208.
2.2AGGREGATE
A.Use 100 percent manufactured sand, slag, crushed fines, or a
combination. Refer to AASHTO M 29.
B.Use aggregate that is clean and free from organic matter or other
detrimental substances.
Asphalt Slurry Seal Coat
C.Use an aggregate blend with a sand equivalent of 45 or more. Refer to
AASHTO T 176.
D.Meet a minimum polishing value of 31. Refer to AASHTO T 278 and
AASHTO T 279.
E.Use aggregate with 35 percent or less loss by abrasion. Refer to
AASHTO T 96.
F.Meet 15 percent soundness maximum using Na2 SO4. Refer to AASHTO
T 104.
2.3MINERAL FILLER
A.Use Portland Cement, hydrated lime, or aluminum sulfate. Refer to
AASHTO M 17.
2.4COMBINED AGGREGATE AND MINERAL FILLER
A.Use a job mix or target gradation within the gradation band.
1.Base the mix design on this gradation.
2.The percent passing each sieve after the target gradation has been
submitted will not vary by more than the target tolerance and still remain within the gradation band in Table 1.
3.Refer to AASHTO T 11 and AASHTO T 27.
Table 1 Gradation Gradation Band Sieve Size Target Tolerance (% Passing) ⅜ inch 100 No. 4 70-90 +/- 5% No. 8 45-70 +/- 5% No. 16 28-50 +/- 5% No. 30 19-34 +/- 5% No. 50 12-28 +/- 4% No. 100 7-18 +/- 3% No. 200 5-15 +/- 2%
2.5WATER
A.Potable and free from harmful salts and contaminants.
Asphalt Slurry Seal Coat
2.6ADDITIVES
A.Additives may be used to accelerate or retard the break-set of the slurry
seal or to improve the resulting finished surface.
2.7SLURRY SEAL MIX DESIGN
A.Use a Department approved laboratory that is qualified to perform the
ISSA A105 tests listed in Table 2.
1.Use the same materials and aggregate gradation to be used on the
project.
Table 2 TESTS ISSA TEST NO. DESCRIPTION SPECIFICATION 2cm Minimum ISSA TB 106 Slurry Seal Consistency 3cm Maximum Wet Cohesion 30 Minutes 12 kg-cm Minimum ISSA TB-139 Minimum (Set) For quick-traffic systems Wet Cohesion 60 Minutes 20 kg-cm Minimum Minimum ISSA TB 109 Excess Asphalt by LWT Sand 50 g/ft2 Maximum For heavy-traffic areas only Abrasion (538 g/m2 Maximum) ISSA TB-114 Wet Stripping Pass (90% Minimum) Wet-Track Abrasion Loss, ISSA TB-100 75 g/ft2 (807 g/m2) One-hour Soak Controllable to 180 ISSA TB-113 Mix Time** Seconds Minimum ** Perform the mixing test and set-time test at the highest temperatures expected during construction.
2.8EQUIPMENT
A.Use only a machine designed and manufactured specifically for blending,
mixing, and placing slurry seal.
1.Mix the material in a self-propelled, slurry seal mixing machine of
either truck-mounted or continuous-run design.
a.Continuous-run machines – Equipped to self-load materials
while continuing to lay slurry seal.
b.Either type machine – Accurately deliver and proportion the
aggregate, emulsified asphalt, mineral filler, control setting additive, and water to a revolving mixer and to discharge the mixed product on a continuous-flow basis.
Asphalt Slurry Seal Coat
2.Maintain sufficient storage capacity within the machine for
aggregate, emulsified asphalt, mineral filler, control additive, and water to maintain an adequate supply to the proportioning controls.
B.Calibrate each mixing unit in the presence of the Engineer before a
machine is used on a project
PART 3 EXECUTION
3.1LIMITATIONS
A.Do not apply slurry seal during rain, when road surface moisture is
present, or during other adverse weather conditions.
B.Do not apply slurry seal if either the pavement or air temperature is below
50 degrees F.
C.Do not apply slurry seal when the temperature is projected to be below 33
degrees F within 24 hours of placing slurry seal.
D.Keep traffic off roadway surface until the slurry seal has cured.
3.2STOCKPILE
A.Remove material not meeting specifications from the stockpile area.
B.Stockpiles not meeting gradation requirements may be corrected and
must be retested before use.
3.3PREPARATION
A.Clean the surface of all dirt, sand, dust, oil, and other objectionable
material immediately before applying the slurry.
B.Allow cracks to dry thoroughly before applying slurry seal when using
water to clean the surface.
C.Protect manholes, valve boxes, drop inlets, and other service utility
entrances before surfacing.
Asphalt Slurry Seal Coat
3.4APPLICATION
A.Pre-wet the entire surface by fogging ahead of the slurry box.
1.Do not over apply, causing free water to sit on the pavement in
front of the slurry box.
B.Use additives as required in accordance with the authorized additive list
and dosage rates submittal.
C.Carry a sufficient amount of slurry in all parts of the spreader at all times
so that full width and complete coverage is obtained with no streaks or narrow spots.
1.Avoid overloading the spreader.
D.Apply slurry mixture of proper consistency at an average rate of 18 to 22
lb/yd2 of dry aggregate.
E.Do not add additional water for any reason, once the mixture has been
placed onto the road surface.
F.Remove and replace the slurry if any of the following occurs:
1.Lumping, balling, or unmixed aggregates.
2.Separation of the coarse aggregate from the emulsion and fines.
3.Settling of the coarse aggregate to the bottom of the mix.
4.Excessive breaking of emulsion inside the spreader box.
5.Streaking caused by oversized aggregate.
3.5FINISHING DETAILS
A.Do not create build-up when constructing longitudinal and transverse
joints.
B.Place slurry seal adjacent to concrete pavements or concrete curb and
gutter with a straight longitudinal edge.
1.Do not allow over-lap on these areas.
2.Remove slurry seal placed on concrete.
C.Maintain straight lines at all locations.
D.Place slurry seal at side streets and intersections out to right-of-way line.
Asphalt Slurry Seal Coat
E.Use hand squeegees to spread slurry in areas that cannot be reached
with slurry seal machine.
1.Lightly dampen areas before mix placement.
2.Provide complete and uniform coverage.
3.Avoid unsightly appearance from hand work.
4.Use the same type of finish in hand worked areas as applied by the
spreader box.
F.Use construction paper or comparable products so all beginning and
ending joint lines from each construction pass are straight.
END OF SECTION
Asphalt Slurry Seal Coat
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Source: Utah Standard Specifications for Road and Bridge Construction, 2026 Edition. Pages 631–637 of 1,331.
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