Presentation delivered by Paul Curren at the 2015 CalAPA Fall Asphalt Pavement Conference Oct. 28-29 in Sacramento, Calif.

1. Superpave – Low
Volume
Paul CURREN, P.E.
Curren Consulting

2. Purpose of Low Volume
Specification
 Caltrans recognizes that 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

3. What is Low Volume?
Mix Design Level Selection Criteria
Traffic Index Mix Design Level
> 8.0 Level I
6.0 to 8.0 Level II
≤ 5.5 Level III

4. Applications of Levels
 Level I is for arterials which have considerable truck traffic.
Aggregate and mix requirements consistent with new 2015
Superpave Specifications with QC and QA modifications
 Level II is for collectors which have medium levels of truck traffic.
Aggregate and mix requirements reflect 2010 HMA requirements for
aggregates and mix requirements
 Level III is for residential streets, parking lots, pathways and
miscellaneous areas. Aggregate and mix requirements more
consistent with 2006 maximum, medium type mixes

5. HMA Mix Design Requirements
Quality characteristic Test method Level I Level II Level III
Air voids content (%)
AASHTO T 269a
Ninitial > 8.0
Ndesign = 4.0
Nmax > 2.0
Ndesign = 4.0 Ndesign = 3.5
Gyration compaction (no. of gyrations)
AASHTO T 312
Ninitial = 8
Ndesign = 85
Nmax = 130
Ndesign = 65 Ndesign = 65
Voids in mineral aggregate (min, %)b
Gradation:
No. 4
3/8-inch
1/2-inch
3/4-inch
SP-2
Asphalt Mixture
Volumetrics 16.5–19.5
15.5–18.5
14.5–17.5
13.5–16.5
16.0–19.0
15.0–18.0
14.-0–17.0
13.0–16.0
15.5–18.5
14.5–17.5
13.5–16.5
12.5–15.5
Dust proportion SP-2 0.6–1.3 0.5–1.4 NA
Hamburg wheel trackd (min number of passes at
0.5-inch rut depth)
Binder grade:
PG 58
PG 64
PG 70
PG 76 or higher
AASHTO T 324
(Modified)c
10,000
15,000
20,000
25,000
10,000
15,000
20,000
25,000
8,000
12,000
15,000
20,000
Hamburg wheel trackd (min number of passes at
the inflection point)
Binder grade:
PG 58
PG 64
PG 70
PG 76 or higher
AASHTO T 324
(Modified)c
10,000
10,000
12,500
15,000
10,000
10,000
12,500
15,000
8,000
8,000
10,000
12,000

6. Aggregate Quality Requirements
Quality characteristic
Requirement
Test method Level I Level II Level III
Aggregate gradationa AASHTO T 27 JMF ± Tolerance
Percent of crushed particles
Coarse aggregate (min, %)
One-fractured face
Two-fractured faces
Fine aggregate (min, %)
(Passing No. 4 sieve
and retained on No. 8 sieve.)
One fractured face
AASHTO T 335
95
90
70
50
50
20
25
20
Los Angeles Rattler (max, %)
Loss at 100 Rev.
Loss at 500 Rev.
AASHTO T 96 12
40 45 50
Sand equivalent (min.)b, c AASHTO T 176 47 45 42
Flat and elongated particles (max, %
by weight at 5:1)
ASTM D4791 10 NA
NA
Nonmanufactured sand, (max, %) 10 10 20e

7. Acceptance Criteria
Level I Level II Level III
Quality characteristic Test method Requirement
Asphalt binder content (%) AASHTO T 308
Method A
JMF -0.3, +0.5 JMF ± 0.50 JMF ± 0.50
HMA moisture content (max, %) AASHTO T 329 1
Air voids content at Ndesign (%)a, b AASHTO T 269 4.0 ± 1.5 4.0 ± 1.5 3.5 ± 2.0
Voids in mineral aggregate on plant-produced HMA
(min, %)a
Gradation:
No. 4
3/8-inch
1/2-inch
3/4-inch
SP-2 Asphalt Mixture
Volumetricsc
15.5–18.5
14.5–17.5
13.5–16.5
12.5–15.5
15.0–18.0
14.0–17.0
13.0–16.0
12.0–15.0
NA
Dust proportion SP-2 0.6–1.3 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
California Test 375
91–97
Method Process of
Construction
Hamburg wheel track
(min number of passes at 0.5-inch rut depth)
Binder grade:
PG 58
PG 64
PG 70
PG 76 or higher
AASHTO T 324
(Modified)
10,000
15,000
20,000
25,000
7,500**
12,500
17,500
20,000
NA
Hamburg wheel track
(min number of passes at inflection point)
Binder grade:
PG 58
PG 64
PG 70
PG 76 or higher
AASHTO T 324
(Modified)
10,000
10,000
12,500
15,000
NA NA

8. 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 inch

9. 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 correlated 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

10. Smoothness
 Eliminates Inertial Profiler
 12 Foot Straight Edge Standard Measurement

11. Excludes:
 INTERLAYERS
 REPLACE ASPHALT CONCRETE SURFACING (DIGOUTS)
 MIX VERIFICATION (Production Startup Only)

12. Other:
 Provides default binder of PG64-10 ro 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.

13. Status:
 Draft Specification sent out to Industry and Agency partners for
review and comment in spring.
 Caltrans has requested work to cease until other 2015 Section 39
issues resolved

14. Acknowledgements:
 HMA-LV Co-chairman: Tim Denlay and Kee Foo
 CalAPA: Russ Snyder and Rita Leahy

15. Questions?