HomeMy WebLinkAbout3307; CARLSBAD BLVD SHORE PROTECTION; GEOTECHNICAL PAVEMENT EVALUATION; 1991-03-05J R4
LEIGHTON AND ASSOCIATES, INC
LJ 11 Geotechnical and Environmental Engineering Consultants
GEOTECHNICAL PAVEMENT EVALUATION,
TAMARACK AVENUE BETWEEN
CARLSBAD BOULEVARD AND
JEFFERSON STREET, CARLSBAD,
CALIFORNIA.
March 5, 1991
Project No. 8910218-01-
Prepared For:
CITY OF CARLSBAD
2075 Las Palmas Drive
Carlsbad, California 92009
5421 AVENIDA ENCINAS, SUITE C, CARLSBAD. CALIFORNIA 92008 (619) 931-9953
•
FAX (619) 931-9326
8910218-01
of the subgrade soils was obtained for laboratory testing. Subsequent to excavation, the core
holes were backfilled and cold-patched.
Laboratory testing consisted of a determination of asphaltic concrete density, soil gradation, sand
equivalent, and R-value tests. Results of the laboratory tests are presented in Appendix D.
Summary of Subrade and Pavement Conditions
The following presents a summary of our observations and analysis of Tamarack Avenue.
Asphalt concrete thicknesses encountered in pavement cores are summarized in Table 1. Core
locations are shown on Plates 1 through 5. Photographs of typical distress features are provided
in Appendix C.
Pavement Conditions
The pavement of Tamarack Avenue between Jefferson Street and Carlsbad Boulevard was
generally in fair to good condition with isolated areas of distress. Distress features that were
observed during our investigation included alligator cracking, potholes, minor depressions
associated with deficient drainage, longitudinal and transverse cracking, polished aggregate,
and raveling. A significant amount of the transverse and longitudinal cracks appeared to be
directly related to cold Joints within the pavement associated with previous utility trench
excavation, backfill and repaving. Deficient drainage, raveling and minor potholing were
particularly evident near the pavement shoulders.
Inspection, of the cores obtained during our investigation indicated that two distinct portions
of Tamarack Avenue, each having a characteristic thickness of full-depth asphalt, can be
identified. As observed in cores AC-11 through AC-3, the pavement thickness of Tamarack
Avenue between Jefferson Street and Hibiscus Circle ranged from 2.6 inches to 3.4 inches,
with an average pavement density of approximately 138 pounds per cubic foot. As
encountered in cores AC-4 through AC-7, the pavement of Tamarack Avenue between
Hibiscus Circle and Carlsbad Boulevard ranged in thickness from 4.1 inches to 7.4 inches,
while the average pavement density was approximately 139 pounds per cubic foot.
Subcirade
As observed during our investigation, the pavement of Tamarack Avenue is underlain by
Quaternary-aged marine terrace deposits typical of the Carlsbad area. These subgrade soils
generally consisted of red-brown, slightly damp, medium dense, silty sands.
Discussion and Recommendations
The pavement is generally in a good condition and is suitable to be overlaid and utilized as part
of the future improvements of Tamarack Avenue. Areas of observed pavement distress features
are identified on Plates 1 through 5. Where alligatored and/or potholed pavements are present,
further degradation of pavement and subgrade is likely due to water infiltration into the subgrade,
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8910218-01
- loss of fines through cracks in the pavement, and poor distribution of wheel loads to the
subgrade. If an asphaltic concrete overlay is placed directly over alligatored and/or potholed
pavement, reflection cracking is likely to occur. Therefore, we recommend removal and
replacement of pavement in these areas. Those areas not identified for replacement are
anticipated to receive an overlay as recommended in Table 1.
Where localized pavement replacement has been recommended, the design pavement section
as recommended in Table 1 has been calculated In accordance with the Caltrans Design Manual.
Overlay thickness has been determined in accordance with the Asphalt Institute Manual (MS-1 7).
Based on our conversations with representatives of The City of Carlsbad, we have utilized design
traffic indices 6.0, 7.0, and 8.0. The recommended overlay and replacement section thickness
for each design traffic index is summarized below. Please note that existing pavements have
been placed on native soils without aggregate base. For pavements to be replaced, we have
indicated the current City minimum design sections (with aggregate base) and full-depth asphalt
sections based on the subgrade A-value. The City minimum design sections are more
substantial and would provide a better pavement durability. However, the City of Carlsbad
should select the appropriate design section based on the alternatives provided.
TABLE 1
Tamarack Avenue - Jefferson Street to Hibiscus Circle
Traffic
Index
Minimum Overlay
Thickness
(in inches)
Minimum Pavement
Replacement Section*
(in inches)
Minimum Full-Depth
Asphalt and
Replacement Section**
(in inches)
6.0 2.0 4 A.C./6 A.B. 4.0
7.0 2.0 4 A.C./6 A.B. 4.0
8.0 1 2.0 1 4.5 A.C./6 A.B. 5.0
Tamarack Avenue - Hibiscus Circle to Carlsbad Boulevard
6.0 1.0 4 A.C./6 A.B. 4.0
7.0 1.0 4 A.C./6 A.B. 4.0
IL-8-0 1.0 4.5 A.C./6 A.B. 5.0
* Based on City of Carlsbad's minimum design sections.
** Design pavement section based on subgrade A-value.
Aggregate Base (A.B.) should conform to Caltrans Class II specifications.
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It should be noted that some distress features in the pavements may be present which were not
visible at the time of our study. Therefore, we recommend that pavements to be overlaid be
checked for additional evidence of distress after surface milling and prior to overlay construction.
In order to reduce the potential for reflection cracking and joint distortion, we recommend that 5
a pavement reinforcing fabric such as Petromat be applied to the pavement along existing joint
utility backfill areas and along seams within the pavement prior to overlay. The fabric should
extend at least 1 foot outside of these areas of cracking or wider, if necessary, to facilitate
placement. IA addition, we recommend that areas of longitudinal, transverse or shrinkage cracks
be slurry sealed prior to overlay.
Where removal and replacement of pavement is recommended, subgrade soils should be
inspected for soft spots or saturation. Subgrade soils in pavement replacement areas should be
brought to near-optimum moisture conditions and compacted to at least 95 percent relative
compaction (ASTM Test Method D1557-78). Aggregate base should also be compacted to
95 percent (ASTM Test Method Dl 557-78).
Please do not hesitate to contact this office if you have, any questions regarding our report. We
appreciate this opportunity to be of service.
Respectfully submitted,
LEIGHTON AND ASSOCIATES, INC.
L~W'Qr--k-'
Michael R. Stewart, CEG 1349 (Exp. 6/30/92).
Chief Geologist
/7r4J Lj2
Stan Helenschmidt, GE 2064 (Exp. 6/30/92)
Chief Engineer/Manager
WM/MRS/SRH/mss
Distribution: (3) Addressee
Attachments: Plates 1 through 5 - Pavement Evaluation
Appendix A - References
Appendix B - Asphalt Pavement Rating
Appendix C - Photographs of Distress Features
Appendix D - Laboratory Test Results
Appendix E - Pavement Section and Overlay Calculations
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8910218-01
APPENDIX E
PAVEMENT SECTION AND OVERLAY CALCULATIONS
SUMMARY OF ASPHALTIC CONCRETE THICKNESS AND DENSITY
Core Number Average Thickness . Measured Density
AC-1 3.1" 142.4 pcf
AC-2 34" 140.3 pct
1 AC-3 . 2.6" 132.2 pcf
AC-4 .. 6.31 138.9 pcf
AC-5 . 7.4" 140.5 pcf
1. AC-6 5.6" 137.8 pcf
1 AC-7 4.1" . 137.8 pcf
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APPENDIX E
EQUIVALENT AXLE LOAD CALCULATIONS (20-Year)
TAMARACK AVENUE: JEFFERSON STREET TO CARLSBAD BOULEVARD
TI=9.0
(EAL 119
IO6)
TI=6.0
EAL=106X.119J 6.0 9.0
11=7.0
EAL=106X.1194j :
Tl=8.0
EAL=106X.1194 9.0
T8. 0
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APPENDIX E
PAVEMENT SECTION AND OVERLAY CALCULATIONS
PAVEMENT SECTION DESIGN
PROJECT DESCRIPTION: REMOVAL AND REPLACEMENT DESIGN OF TAMARACK AVENUE
-ASSUMING T16.0
DESIGN A-VALUE OF .SUBGRADE (R) = 71.0
DESIGN TRAFFIC INDEX (TI) = 6.0
GRAVEL EQUIVALENT (G.E.) = 0.0032 * 6.0 * (100. -71.0)
= 0.66 FEET
RECOMMENDED PAVEMENT SECTION IS:
4.0 INCHES ASPHALTIC CONCRETE OVER
6.0 INCHES CALTRANS CLASS II AGGREGATE BASE
OR
4.0 INCHES FULL-DEPTH ASPHALTIC CONCRETE
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APPENDIX E
PAVEMENT SECTION AND OVERLAY CALCULATIONS
PAVEMENT SECTION DESIGN
PROJECT DESCRIPTION: REMOVAL AND REPLACEMENT DESIGN OF TAMARACK AVENUE
ASSUMING 11=7.0
DESIGN R-VALUE OF SUBGRADE (R) = 71.0
DESIGN TRAFFIC INDEX. (TI) = 7.0
GRAVEL EQUIVALENT (G.E.) = 0.0032 * 7.0 * (100. -71.0)
= 0.75 FEET
RECOMMENDED PAVEMENT SECTION IS:
4.0 INCHES ASPHALTIC CONCRETE OVER
6.0 INCHES CALTRANS CLASS II AGGREGATE BASE
OR
4.0 INCHES FULL-DEPTH ASPHALTIC CONCRETE
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APPENDIX E
PAVEMENT SECTION AND OVERLAY CALCULATIONS
PAVEMENT SECTION DESIGN
PROJECT DESCRIPTION: REMOVAL AND REPLACEMENT DESIGN OF TAMARACK AVENUE
ASSUMING TI=8.0
DESIGN R-VALUE OF SUBGRADE (R) = 71.0
DESIGN TRAFFIC INDEX (TI) = 8.0
GRAVEL EQUIVALENT (G.E.) = 0.0032 '*8.0 * (100. -71.0)
= 0.84 FEET
RECOMMENDED PAVEMENT SECTION IS:
4.5 INCHES ASPHALTIC CONCRETE OVER
6.0 INCHES AGGREGATE BASE
OR
5.0 INCHES FULL-DEPTH ASPHALTIC CONCRETE
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APPENDIX E
PAVEMENT SECTION AND OVERLAY CALCULATIONS
Effective Thickness Design for Overlay
J Street - Tamarack Avenue (TI=6.0)
Setion - Jefferson Street to Hibiscus Circle
A.C. Average Thickness = 3.0"
From Table V-2 of Asphalt Institute MS-1 7
TQ(A C) = 07 (3.(Y-) = 21"
Te(TOtal) = 2.1" = 2.0"
Mr = 1,155 + 555 (A-value) ••
=1,155+555(71).
= 40,560 psi
For TIof6.0 - 20-YearEAL=3.3x104
= 4.0" (Minimum)
T. = 4.0" - 2.0" = 2.0"
Use 2.0" Overlay
Based on Cores AC-1 through AC-3
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APPENDIX E
PAVEMENT SECTION AND OVERLAY CALCULATIONS
Effective Thickness Design for Overlay
Street - Tamarack Avenue (TI=7.0)
Section - Jefferson Street to Hibiscus Circle
A.C. Average Thickness = 3.0"
From Table V-2 of Asphalt Institute MS-1 7
T0(A.C) = 0.7 (3.0) = 2.1"
T0frotal) = 2.1" = 2.0"
Mr = 1,155 + 555 (R-value).
=1,155+555(71)
= 40,560 psi
For llof7.0 - 20-YearEAL= 1.2x105
= 4.0" (Minimum)
T. = 4.0" - 2.0" = 2.0"
Use 2.0" Overlay
Based on Cores AC-1 through AC-3
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APPENDIX E
PAVEMENT SECTION AND OVERLAY CALCULATIONS
Effective Thickness Design for Overlay
Street - Tamarack Avenue (11=8.0)
Section - Jefferson Street to Hibiscus Circle
A.C. Average Thickness = 3.0"
From Table V-2 of Asphalt Institute MS-1 7
TQ(A.C) = 0.7 (3.0") = 2.1"
10(Total) = 2.1" 2.0"
Mr = 1,155 + 555 (A-value)
= 1,155 + 555 (71)
= 40,560 psi
For T1 of 8.0 - 20-Year EAL=3.7x105
T = 4.0" (Minimum)
T. = 4.0" - 2.0" = 2.0"
Use 2.0" Overlay
Based on Cores AC-1 through AC-3
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APPENDIX E
PAVEMENT SECTION AND OVERLAY CALCULATIONS
Effective Thickness Design for Overlay
Street - Tamarack Avenue (11=6.0)
Section - Hibiscus Circle to Carlsbad Boulevard
A.C. Average Thickness = 5.9"
From Table V-2 of Asphalt Institute MS-1 7
T0(A C) = 07 (59") = 4.1"
Te(TOtal) = 4.1" = 4.0"
Mr = 1,155 + 555 (R-value)
=1,155+555(71)
= 40,560 psi
For TI of 6.0 - 20-Year EAL = 3.3 x 104
T = 4.0' (Minimum)
T. = 4.0"- 4•0U = Q
No Overlay Required
Based on Cores AC-4 through AC-7
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APPENDIX E
PAVEMENT SECTION AND OVERLAY CALCULATIONS
Effective Thickness Design for Overlay
Street - Tamarack Avenue (11=7.0)
Section - Hibiscus Circle to Carlsbad Boulevard
A.C. Average Thickness = 5.9"
From Table V-2 of Asphalt Institute MS-17
TO(A C) = 07 (59") = 41"
T0(lotal) = 4.1" = 4.0"
Mr = 1,155 + 555 (R-value)
= 1,155 + 555 (71)
= 40,560 psi
For 11 of 7.0 - 20-Year EAL= 1.2x 105
T = 4.0" (Minimum)
T0 = 4.0" - 4.00 = 0
No Overlay Required
Based on Cores AC-4 through AC-7
E-1 0
8910218-01
ii
APPENDIX E
PAVEMENT SECTION AND OVERLAY CALCULATIONS
Effective Thickness Design for Overlay
Street - Tamarack Avenue (11=8.0)
Section - Hibiscus Circle to Carlsbad Boulevard
A.C. Average Thickness = 5.9"
From Table V-2 of Asphalt Institute MS-1 7
10(A C) = 07 (59") = 41"
10(lotal) = 4.1" = 4.0"
Mr = 1,155 + 555 (R-value)
= 1,155 + 555 (71)
= 40,560 psi
For TI of 8.0 - 20-Year EAL = 3.7 x 10-9
T = 4.' (Minimum)
T0 =4.'-4.'=O
No Overlay Required
E-1 1
Based on .Cores AC-4 through AC-7