Superpave – Low VolumePaul CURREN, P.E.Curren Consulting

Purpose of Low Volume Specification

Caltrans recognizes that the new Section 39 Superpave specification may not be applicable to many local agency projects

Desire by Industry and Agency partners to allow for mixes generally accepted based on past specifications i.e. maximum medium (2006) and HMA (2010)

Allowance for lower cost aggregates (Type B) which perform well on low volume roadways

Reduced QC and QA requirements for lower volume roads due to less performance risk

Update on Changes to SP-LV

Original Work (presented last year in 2015) Intended for use by Municipalities for all of their projects Included all Traffic Indexes (Tis) Included 3 levels

Level 1 > 8.0 Level 2 = 6.0 to 8.0 Level 3 = 5.5 or less

2016 Update Includes TI of 8.0 or less

Current Version Levels

Mix Design Level Selection CriteriaTraffic Index Mix Design Level6.0 to 8.0 Level I≤ 5.5 Level II

Applications of Levels

Level I is for collectors which have medium levels of truck traffic. Aggregate and mix requirements reflect 2010 HMA requirements for aggregates and mix requirements

Level II is for residential streets, parking lots, pathways and miscellaneous areas. Aggregate and mix requirements more consistent with 2006 maximum, medium type mixes

General Modifications

JMF good for 24 months Verification testing not required JMF properties tested at Production Startup Requires Contractor QC Plan submittal concurrently with JMF COC for Liquid Anti-Strip For Warm Mix, contractor proposes production and compaction

temperature ranges Allows for HMA Plant Qualification by Engineer as well as Caltrans Must retain 1 sample part for dispute resolution

Modifications Continued

Eliminates automatic screed controls

Density Requirements

QC Requirements Requires only 5 locations with 1 core per location for gauge

correlation (not the 20 cores per CT 375). Must also correlate QA gauge at same time.

Allows non-nuclear correlated gauges Maximum lots of 500 tons 1 gauge test per 50 tons, 3 minimum If cores required, 1 per 250 tons, contractor takes cores 

QA Requirements Allows acceptance by correlated gauge density or cores

Smoothness

Eliminates Inertial Profiler 12 Foot Straight Edge Standard Measurement Contains California Profilegraph Requirements

Other:

Provides default binder of PG64-10 or PG 64-16

Requires any agreed upon changes to Method Compaction to be in writing

Changes QC and QA testing requirements and frequencies Example: Binder Content, Gradation and Sand Equivalent are

1,500 ton intervals and carry over day to day.

Legislative Mandate – AB 2335

Effective January 1, 2017, local agencies must use Caltrans standards/specs for recycled paving materials … or at public hearings discuss why the standards/specs are NOT being implemented

Gradation Change Comparison

Sieve sizes 2006 2010 2015 2006 2010 20151" 100 100 100 100 100 1003/4" 95 90 90 100 100 981/2" 70 70 90 903/8" 65 80No. 4 49 45 42 54 55 58No. 8 36 32 29 40 40 43No. 30 18 12 10 21 21 23No. 200 3 2 2 8 7 7

3/4" HMA - 2006 Max Medium

HighJMF - Target Value Limits

Low

2006 ½” Max. Medium vs2015 3/8” HMA

Sieve sizes 2006 2015 2006 20153/4" 100 100 100 1001/2" 95 100 100 1003/8" 80 95 95 98No. 4 54 55 71 75No. 8 38 34 54 50No. 30 17 15 32 35No. 200 3 2 8 9

Low High

HMA Mix Design RequirementsQuality characteristic Level I Level II

Voids in mineral aggregate (min, %)b

Gradation:No. 4 16.0–19.0 15.5–18.53/8-inch 15.0–18.0 14.5–17.51/2-inch 14.-0–17.0 13.5–16.53/4-inch 13.0–16.0 12.5–15.5

Dust proportion 0.5–1.4 NAHWT

Binder grade:PG 58 10,000 8,000PG 64 15,000 12,000PG 70 20,000 15,000PG 76 or higher 25,000 20,000

Air voids content (%) Ndesign = 4.0 Ndesign = 3.5

Gyration compaction (no. of gyrations) Ndesign = 65 Ndesign = 65

Aggregate Quality Requirements

Level I Level II

Aggregate gradationa

Percent of crushed particlesCoarse aggregate (min, %)

One-fractured face 50 25Two-fractured faces 50 NA

Fine aggregate (min, %)(Passing No. 4 sieveand retained on No. 8 sieve.)One fractured face 20 20

Los Angeles Rattler (max, %)Loss at 500 Rev. 45 50

Sand equivalent (min.)b, c 45 42Flat and elongated particles (max, % by weight at 5:1) NA NA

Nonmanufactured sand, (max, %) 10 20e

RequirementQuality characteristic

Acceptance CriteriaLevel I Level II

Quality characteristic

Asphalt binder content (%) JMF ± 0.50 JMF ± 0.50

HMA moisture content (max, %) 1Air voids content at Ndesign (%)a, b 4.0 ± 1.5 3.5 ± 2.0Voids in mineral aggregate on plant-produced HMA (min, %)a

Gradation:No. 43/8-inch 15.0–18.0 NA1/2-inch 14.0–17.03/4-inch 13.0–16.0

12.0–15.0Dust proportion 0.5–1.4 NA

Density of HMA by non-destructive density device correlated to cores or (if specified) by core (% of max theoretical density)e, f

91–97 Method Process of Construction

Hamburg wheel track(min number of passes at 0.5-inch rut depth)

Binder grade:PG 58 7,500**PG 64 12,500PG 70 17,500PG 76 or higher 20,000

Hamburg wheel track(min number of passes at inflection point)

Binder grade:NA NA

NA

Aggregate Size by Lift Thickness

Type A HMA pavement lift thickness Gradation

0.10 foot ⅜ inch

Greater than 0.10 to less than 0.20 foot ½ inch

0.20 foot or greater ½ or ¾ inch0.25 foot or greater ¾ inch

Modifications to Compaction Temperature Ranges

07-15-16 Minimum Ambient Air and Surface Temperatures

Lift thickness (feet)

Ambient air (F) Surface (F) Unmodified asphalt

binder Modified asphalt

binder Unmodified asphalt

binder Modified asphalt

binder Type A HMA and Type A HMA produced with WMA water injection technology

0.15 55 50 60 55 ≥0.15 45 45 50 50

Type A HMA produced with WMA additive technology 0.15 45 45 50 45 ≥0.15 40 40 40 40

Status:

Draft Specification sent out to Industry and Agency partners for review and comment in spring.

NEED DATA Need Owners and Suppliers to test existing mixes to provide

information to compare historically performing mixes to proposed requirements.

Acknowledgements:

HMA-LV Co-chairman: Tim Denlay and Kee Foo

CalAPA: Russ Snyder and Brandon Milar

Questions?