Open- Graded Surface Course (OGSC) OPEN -GRADED SURFACE COURSE (OGSC)
Part 1 — General
1.1 Section Includes
A.Materials and procedures for constructing OGSC
1.2 Related Sections
A.Section 01456 Materials Dispute Resolution
B.Section 02701 : Pavement Smoothness
C.Section 02745: Asphalt Material
D.Section 02746: Hydrated Lime
E.Section 02748: Prime Coat/Tack Coat
1.3 References
A.AASHTO T 30: Mechanical Analysis of Extracted Aggregate
B.AASHTO T 89: Determining the Liquid Limit of Soils
C.AASHTO T 90: Determining the Plastic Limit and Plasticity Index of Soils
D.AASHTO T 96: Resistance to Degradation of Small Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine
E.AASHTO T 104: Soundness of Aggregate by Use of Sodium Sulfate or Magnesium Sulfate
F.AASHTO T 112: Clay Lumps and Friable Particle in Aggregate
G.AASHTO T 176: Plastic Fines in Graded Aggregates and Soils by Use of the Sand Equivalent Test
H.AASHTO T 278: Surface Frictional Properties Using the British Pendulum Tester Open- Graded Surface Course (OGSC)
I.AASHTO T 279: Accelerated Polishing of Aggregates Using the British Wheel
J.AASHTO T 304: Uncompacted Void Content of Fine Aggregate
K.AASHTO T 308: Determining the Asphalt Binder Content of Asphalt Mixtures by the Ignition Method
L.AASHTO T 335: Determining the Percentage of Fracture in Coarse Aggregate
M.UDOT Materials Manual of Instruction
N.UDOT Minimum Sampling and Testing Requirements
1.4 Definitions
A.Production Day – A 24-hour period in which OGSC is being placed.
1.5 Submittals
A.Job mix gradation for approval
1.Materials and documentation according to Materials Manual of Instruction, Section 954.
2.Aggregate suitability test results.
B.Changes in J ob Mix Gradation
1.Written request for a change in a job- mix gradation for approval .
2.Allow the Engineer five working days to review and respond to the changes and to readjust the quantity of asphalt binder to be used.
1.6 Acceptance
A.Acceptance sampling and testing of material is according to UDOT Minimum Sampling and Testing Requirements.
B.Gradation and asphalt binder content
1.The Engineer evaluates a lot on the test results of four or more samples, except when only three samples can be taken.
2.Evaluate the lot using the number of tests “n” in Table 3.
3.The Engineer informs the Contractor of the time and place of sampling not more than 15 minutes before sampling.
4.Increase sample sizes to accommodate validation or third- party testing as required. Open- Graded Surface Course (OGSC)
C.The Department applies one Incentive/Disincentive for the lowest dollar value for Gradation/Asphalt Content . The Engineer computes the Incentives/Disincentives as follows for each lot
1.Compute incentive/disincentive for Gradation/Asphalt Binder according to Table 1.
2.Base the incentive/disincentive on Percent within Limit (PT) computation using Tables 2, 3, and 4.
3.Use lowest single PT value combined for gradation (each of the sieves) and asphalt binder content for calculating the gradation/asphalt binder content incentive/disincentive.
D.Thickness
1.Verify the thickness with a depth probe and take corrective action if necessary.
a.Minimum thickness – Plan depth minus ¼ inch.
E.Smoothness
1.The Department applies incentive/disincentive for smoothness according to Section 02701.
2.Refer to Section 02701 for smoothness requirements.
F.The Department rejects lots
1.If the PT for any individual gradation measurement is less than 52 percent as shown in Table 1.
2.If the PT for asphalt binder content is less than 60 percent as shown in Table 1.
3.The Engineer may accept a reject or non- conforming lot. Refer to Section 01456.
a.A price reduction of 35 percent for the OGSC pay item and a price reduction of 35 percent for the binder pay item will be assessed .
b.The lot will not be eligible for any incentive. Open- Graded Surface Course (OGSC) Table 1 Incentive/Disincentive for Asphalt Binder Content PT Based on Min. Four Samples Incentive/Disincentive (Dollars/Ton) >99 96-99 92-95 88-91 84-87 80-83 76-79 72-75 68-71 64-67 60-63 <60 2.00 1.50 1.00 0.00 -0.26 -0.60 -0.93 -1.27 -1.60 -1.93 -2.27 Reject Incentive/Disincentive for Gradation PT Based on Min. Four Samples Incentive/Disincentive (Dollars/Ton) >99 96-99 92-95 88-91 84-87 80-83 76-79 72-75 68-71 64-67 60-63 56-59 52-55 <52 2.00 1.50 1.00 0.00 -0.26 -0.60 -0.93 -1.27 -1.60 -1.93 -2.27 -5.00 -10.00 Reject Table 2 Upper and Lower Limit Determination Parameter UL and LL Asphalt Binder Content Target Value ± 0.35% ⅜ inch sieve Target Value ± 6.0% No. 4 sieve Target Value ± 6.0% No. 8 sieve Target Value ± 5.0% No. 200 sieve Target Value ± 2.0% Open- Graded Surface Course (OGSC) Table 3 Quality Index Values for Estimating Percent Within Limits PU/PL n=3 n=4 n=5 n=6 n=7 n=8 n=10 n=12 N=15 n=20 100 1.16 1.50 1.75 1.91 2.06 2.15 2.29 2.35 2.47 2.56 99 1.16 1.47 1.68 1.79 1.89 1.95 2.04 2.09 2.14 2.19 98 1.15 1.44 1.61 1.70 1.77 1.80 1.86 1.89 1.93 1.97 97 1.15 1.41 1.55 1.62 1.67 1.69 1.74 1.77 1.80 1.82 96 1.15 1.38 1.49 1.55 1.59 1.61 1.64 1.66 1.69 1.70 95 1.14 1.35 1.45 1.49 1.52 1.54 1.56 1.57 1.59 1.61 94 1.13 1.32 1.40 1.44 1.46 1.47 1.49 1.50 1.51 1.53 93 1.12 1.29 1.36 1.38 1.40 1.41 1.43 1.43 1.44 1.46 92 1.11 1.26 1.31 1.33 1.35 1.36 1.37 1.37 1.38 1.39 91 1.10 1.23 1.27 1.29 1.30 1.31 1.32 1.32 1.32 1.33 90 1.09 1.20 1.23 1.24 1.25 1.25 1.26 1.26 1.27 1.27 89 1.08 1.17 1.20 1.21 1.21 1.21 1.21 1.21 1.22 1.22 88 1.07 1.14 1.16 1.17 1.17 1.17 1.17 1.17 1.17 1.17 87 1.06 1.11 1.12. 1.12 1.12 1.13 1.13 1.13 1.13 1.13 86 1.05 1.08 1.08 1.08 1.08 1.08 1.08 1.08 1.08 1.08 85 1.03 1.05 1.05 1.05 1.05 1.04 1.04 1.04 1.04 1.04 84 1.02 1.02 1.02 1.01 1.01 1.01 1.00 1.00 1.00 1.00 83 1.00 0.99 0.98 0.97 0.97 0.96 0.96 0.96 0.96 0.96 82 0.98 0.96 0.95 0.94 0.94 0.93 0.93 0.92 0.92 0.92 81 0.96 0.93 0.92 0.91 0.90 0.90 0.89 0.89 0.89 0.88 80 0.94 0.90 0.88 0.87 0.86 0.86 0.85 0.85 0.85 0.85 79 0.92 0.87 0.85 0.84 0.83 0.83 0.82 0.82 0.82 0.81 78 0.89 0.84 0.82 0.81 0.80 0.79 0.79 0.78 0.78 0.78 77 0.87 0.81 0.79 .0.78 0.77 0.76 0.76 0.75 0.75 0.75 76 0.84 0.78 0.76 0.75 0.74 0.73 0.72 0.72 0.72 0.72 75 0.82 0.75 0.73 0.72 0.71 0.70 0.69 0.69 0.69 0.68 74 0.79 0.72 0.70 0.68 0.67 0.67 0.66 0.66 0.66 0.65 73 0.77 0.69 0.67 0.65 0.64 0.64 0.62 0.62 0.62 0.62 72 0.74 0.66 0.64 0.62 0.61 0.61 0.60 0.59 0.59 0.59 71 0.71 0.63 0.60 0.59 0.58 0.58 0.57 0.56 0.56 0.56 70 0.68 0.60 0.58 0.56 0.55 0.55 0.54 0.54 0.54 0.53 69 0.65 0.57 0.55 0.54 0.53 0.52 0.51 0.51 0.51 0.50 68 0.62 0.54 0.52 0.51 0.50 0.50 0.48 0.48 0.48 0.48 67 0.59 0.51 0.49 0.48 0.47 0.47 0.46 0.45 0.45 0.45 66 0.56 0.48 0.46 0.45 0.44 0.44 0.43 0.42 0.42 0.42 65 0.53 0.45 0.43 0.42 0.41 0.41 0.40 0.40 0.40 0.39 64 0.49 0.42 0.40 0.39 0.38 0.38 0.37 0.37 0.37 0.37 63 0.46 0.39 0.37 0.36 0.35 0.35 0.35 0.34 0.34 0.34 62 0.43 0.36 0.34 0.33 0.33 0.33 0.32 0.31 0.31 0.31 61 0.39 0.33 0.31 0.30 0.30 0.30 0.29 0.29 0.29 0.28 60 0.36 0.30 0.28 0.27 0.26 0.26 0.25 0.25 0.25 0.25 <60 ≤ 0.35 ≤ 0.29 ≤ 0.27 ≤ 0.26 ≤ 0.25 ≤ 0.25 ≤ 0.24 ≤ 0.24 ≤ 0.24 ≤ 0.24 Enter table in the appropriate “number of tests” column and round down to the nearest value. Open- Graded Surface Course (OGSC) Table 4 Definitions, Abbreviations, and Formulas for Acceptance Term Explanation Target Value (TV) The target values for gradation and asphalt binder content. Average (AVE) The sum of the lot’s test results for a measured characteristic divided by the number of test results , the arithmetic mean. Sample Standard Deviation s The square root of the value formed by summing the squared difference between the individual test results of a measured characteristic and AVE divided by the number of test results minus one. Upper Limit (UL) The value above the TV of each measured characteristic that defines the upper limit of acceptable production. (Table 2) Lower Limit (LL) The value below the TV of each measured characteristic that defines the lower limit of acceptable production . (Table 2) Upper Quality Index (QU) QU = (UL - AVE)/s Lower Quality Index (QL) QL = (AVE - LL)/s Percentage of Lot Within UL (PU) Determined by entering Table 4 with QU. Percentage of Lot Within LL (PL) Determined by entering Table 4 with QL. Total Percentage of Lot (PL) Within UL and LL (PT) PT = (PU + PL) – 100 Incentive/Disincentive Determined by entering Table 3 with PT or PL. All values for AVE, s, QU, and QL will be calculated to at least a two decimal places and will be carried through all further calculations. Rounding to lower accuracy is not allowed.
1.7 Dispute Resolution
A.Refer to Section 01456 when disputing the validity of the Department’s acceptance tests.
Part 2 — Products
2.1 Asphalt Binder
A.Refer to Section 02745.
2.2 Hydrated Lime
A.Refer to Section 02746. Open- Graded Surface Course (OGSC)
2.3 Aggregate Materials
A.Crusher processed virgin aggregate material consisting of crushed stone, gravel, or slag.
B.Meet the following requirements , including Table 5.
1.Coarse aggregate
a.Retained on No. 4 sieve.
2.Fine aggregate
a.Clean, hard grained, and angular.
b.Passing the No. 4 sieve. Table 5 Aggregate Properties Properties Test Method Test Requirement One Fractured Face AASHTO T 335 95 percent min. Two Fractured Face AASHTO T 335 90 percent min. Fine Aggregate Angularity AASHTO T 304 45 min. L.A. Wear AASHTO T 96 30% max. Sand Equivalent AASHTO T 176 60 min. Plasticity Index AASHTO T 89 and T 90 0 Polish Test AASHTO T 278 & T 279 31 min. Soundness (sodium sulfate) AASHTO T 104 12% max. loss with five cycles Clay Lumps and Friable Particles AASHTO T 112 2% max. Natural Fines None None
2.4 Job Mix
A.Obtain Engineer’s review for job mix gradation.
1.Show definite single values for the percentage of aggregate passing each sieve based on the dry weight of aggregate.
2.Stay within the single value gradation limits of Table 6.
3.Incorporate hydrated lime by dry weight of aggregate into all mixtures. Refer to Section 02746. Open- Graded Surface Course (OGSC) Table 6 Aggregate Gradation Percent Passing by Dry Weight of Aggregate Sieve Size Percent ½ inch ⅜ inch # 4 # 8 # 200 100 90 - 100 35 - 45 14 - 20 2 - 4
B.Binder Content
1.The Engineer determines the binder content.
2.5 Tack Coat
A.Refer to Section 02748
Part 3 — Execution
3.1 Mixing
A.Treat the aggregate with hydrated lime. Refer to Section 02746.
B.Mix until all particles are coated with the asphalt binder .
3.2 Surface Placement
A.Apply tack coat. Refer to Section 02748.
B.Maintain a steady paver speed.
C.Roll sufficiently to seat without fracturing aggregate.
D.Bring all passes up even transversely at the end of each working day.
E.Construct longitudinal joints within 6 inches of lane lines.
F.Remove slick spots as determined by the Engineer. Open- Graded Surface Course (OGSC)
3.3 Limitations
A.Place between May 1 and September 15.
1.Obtain authorization from the Engineer before placing OGSC after September 15.
B.Place when the air temperature in the shade and the pavement surface temperature are above 60 degrees F.
C.Do not place if surface moisture is present.
D.Do not place during rain or other adverse weather conditions.
Source: Utah Standard Specifications for Road and Bridge Construction, 2026 Edition. Pages 607–615 of 1,331.