HomeMy WebLinkAbout3166; PALOMAR AIRPORT RD; ASPHALTIC CONCRETE MIX DESIGN REVIEW; 1993-06-22LAW/CRANDALL, INC.
ENGINEERING AND ENVIRONMENTAL SERVICES
2324
June 22, 1993
Richard Cook.
City of Carlsbad
2075 Los Palmas Drive
Carlsbad, California 92009-1519
(2406.20075.0001)
Subject Palomar Airport Road Reconstruction
Asphalt concrete mix design review
Dear Mr. Cook,
As requested by Mr. Cook, LAW/CRANDALL hs reviewed and prepared comments
regarding the adjusted class C2 and class B asphalt concrete mix designs submitted by
Industrial Asphalt. These mix adjustments were made by industrial Asphalt to midigate the
reoccurrence of low and failing stabilometer values that have been recorded by our laboratory
during quality control testing of asphalt concrete placement on the subject project
Class C2 asphalt concrete mix design review
The stabilomer value drops sharply with relatively small increases in asphalt content. • Using
a smooth line curve, (or best fit) we show the S value at Industrial Asphalt (IA)
recommended asphalt content to be 37.
The air voids curve shows a voids content of 2.8 percent. This voids level is below the
generally accepted design range of 3 to 5 percent range.
LAW/CRANDALL, INC.
9177 SKY PARK CT. • SAN DIEGO, CA 92123
(619) 278-3600 • FAX (619) 278-5300
ONIOITHaAWcoANIIS
Richard Cook - -. June 22, 1994
Palomar Airport Road Reconsirucrion .. page 2
The voids mineral aggregate (V.M.A.) is recorded to be 14.9 percent and is borderline
deficient when compared to recommendation made by the Asphalt Institute and other
authoritieS. It is our.opinion that the V.M.A. is contributing to the sensitivity of stabilometer
values to small charges in asphalt content.
Class C2 recommendation
Based on the mix design charts provided by Industrial Asphalt and their recommended asphalt
content of 5.3 percent, we anticipate there is the potential for stabilometer values to fall
below the required minimum of 35. Our conclusion is predicated on the marginal to low air
voids, and increases in asphalt content of 0.2 percent will result in failing stabilometer values.
Without adjusting the V.M.A. to a higher percentage, we recommend reducing the asphalt
content to 4.8 percent.. . .
This adjustment would result in a stabilometer value of 40 with air voids of 4.3 percent. This
asphalt content would. allow for a full 0.5 percent increases in asphalt content while
maintaining stabilometer values above the specified minimum of 35.
S Class .B asphalt concrete mix design review
As with the C2 mix, the stabilometer value drops rather sharply with small increases . in
asphalt content. An increase of 0.5 percent asphalt content over the design content of 4.7
would drop the stabilometer- value to a failing level of 34. The air voids are also on the low
side, adding to the sensitivity of this mix to increases in asphalt content. The sharp drop in
VMA of over 1 percent certainly contributes to the behavior of this asphalt concrete mix.
Class B recommendations . .
As in the C2 mix at Industrial Asphalt recommended asphalt content of 4.7 percent; we
anticipate there is the potential for low stabilometer values to occur within the acceptable
range of asphalt content (4.2 to 5.2%).
Richard Cook June 22, 1994
Palomar Airport Road Reconstruction page 3
We recommend reducing the asphalt content for the class B asphalt concrete to 4.5 percent.
This adjustment would increase both the stabilometer value and air void to acceptable ranges.
Conclusions
For these two asphalt concrete mixes tobe completely acceptable would require a adjusting
the aggregate gradation to increase the V.M.A. Increasing the VMA allows for higher asphalt
content while maintaining air voids between 3-5 percent, with stabilometer values well above
35.. A higher V.M.A. generally tends to flatten the stabi!orneter curve and lessen the
sensitivity to minor changes in asphalt content Perhaps the greatest benefit of increasing the
V.M.A. and allowing for higher asphalt contents is the increase in asphalt film thickness.
Increases in asphalt film thickness translate directly to increase in pavement durability,
extended service life and performance.
In reference to Industrial Asphalt assessment of the causes of low and failing stabilometer
value, we concur that the higher asphalt contents are contributing to the low 'S' values. The
higher amounts passing the #200 sieve also are known to create problems similar to those
associated with high asphalt contents.
Industrial Asphalt has indicated that the variability of materials within their quarry will result
in inconsistent properties within the finished asphalt concrete.
It is our opinion that to preclude further problems with stabilometer values the following
would need to occur: . . . . .
Maintain a constant and consistent source of aggregate
Maintain a uniform asphalt content
Reduce the amount. of 4200
Adjust the combined mineral aggregate gradation to result ma higher V.M.A.
9 Perform AC plant quality control testing during production to assure the above
I
June 2, 1994
Palomar Grading & Paving, Inc.
2150 N. Centre City Pkwy
Escondido, California 92026-1338
Attn: Keith Reilly
Faxi: 619-743-7761
Gentlemen,
On the following pages are current tables and graphs for the
Class B and Class C2 mixtures as requested by Jim Copley of LAW
Crandall.
What appears to be playing a crucial factor in our mixture
which failed S-Value is the amount of bitumen in combination with
the fine materials passing the #200 sieve. This basically
lowered the air voids in the completed mixture and the subsequent
failure. After discussing what occurred with the plant personnel
it seems that we may have had some "sluffing" of the one bin.
This being the case the failed area may be limited.
We have already instructed the plant operators what to watch
for when producing this mixture and hope that this will alleviate
any future problems. We are also performing additional coring
next week to further identify if the failure was isolated.
If you need any further information please feel free to
contact us.
Sincerely,
Edward H. Luce
Supervisor Asphalt
uaniei i-i. npman
Dir.Const.Maerials Lab Agg.
cc: Ray Tompkins -.Vista
Const. Materials Laboratory, 16009 root tiill Blvd.. Irwindale, CA 91706 Phone(88)334-0304 Fax(818)969-2918
ANALYSIS BY WEIGHT OF TOTAL MIXTURE -
CONTRACTOR: PALOMAR GRADING & PAVING
SAMPLE= = = = = = = = => CLASS C2 MIXTURE DATE 02-Jun-94
IDENTIFICATION=> VISTA INDUSTRIAL ASPHALT
MIX DESIGN======>
PALOMAR AIRPORT ROAD
VMA WAS CALCULATED USING= = = => BULK SPECIFIC GRAVITY
COMPOSITION OF PAVING MIXTURE: HVEEM
CONSITITUENT SPECIFIC GRAVITY
MATERIAL
- 1.CRSEAGGT-GI- 49.0 2.800 P1-
2.FINE AGGT-G2- 51.0Y 2.700 P2-
3.MINL FLTR-G3- 0.000 P3-
4.TOTLAGGT-GS- . 2.748 PS-
5.ASPTCEMT-GB- 1.015 PB-
6.BULK SP GR (GRB) TOTAL AGGT
7.MAX SP GR (GMM) PAVING MIX
8.BULK SP GR (GMB) CMPTD MIX
UNIT WEIGHT (#8 X 62.4)
9.EFFECTIVE SP GR (GSE) TOTAL AGGT
10.ABSD ASPLT (PBA%) BY WGT TOT AGGT
11.EFFECTIVE ASPLT CONTENT (PBE)
12.VMA
13.A?R VOIDS (PA)
14.VOIDS FILLED
15.S-VALUE .
16.SWELL
MIX COMPOSITION
WEIGHT OF
%
TOTAL MIX
BY
46.893 46.648 46.403 46.158
48.807 48.552 48.297 48.042
0.000 0.000 0.000 0:000
95.700 95.200 94.700 94.200
4.300 4.800 5.300 5.800
2.748 2.748 2.748 2.748
2.670 2.554 2.540 2.530
2.432 2.445 2.470 2.480
151.76 152.57 154.13 154.75
2.881 2.765 2.773 2.786
1.705 0.227 0.333 0.504
2.652 4.582 4.981 5.320
15.305 15.297 14.880 14.987
8.914 4.268 2.756 1.976
41.8 72.1 81,5 86.8
45.0 40.0 38.0 33.0
0.001 0.001 0.001 0.001
45.9.13
47.787
0.000
93.700
6.300
2.748
2.519
2.472
154.25
2.798
0.660
5.675
15.711
1.866
88.1.
30.0
0.010
R.CONSTRUC N MATERIALS LAB SUPERVISOR ASPHALT AND OGRE 7ATES
155
154.5
'54
UNIT WOT
153.5
153
152.5
152
'SI.,
0.01
0.009
0.008
0.007
'LL 0.006
0.005
0.004
0.003
0.002
0.001
6.300
/I ...... ... ..... ....... ... ........ .........
4.300 4.000 5.300 5.800
ASPHALT CONTENT
I.................................... .......
or ............,
4
......4 ............. .1
4.300 4.800 5.300 5.800 6.300
ASPHALT CONTENT
F
PALOMAR AIRPORT ROAD
C2 MIXTURE
HVEEk4
46
.. :AIUE 42
40 . ....... ....... N ........ .............. ............... ............... .......
.....I.......
4.300 1.800 5 300 5.800 6.300.
ASPHALT CONTENT
9
8
7
AIfl VOIDS 6
I
3
2
ASPHALT CONTENT
".8
15.7
15.8
15.5
V JJ A
I! 3
IS.?
IS. I
IS
14.9
14.8
I I I -
I...............:................................I .....................
I.....................
...... ..... ....... . .... ...... . .. ........ .
II i 4.300 4.800 3.300 1.800 6.300
ASPhALT CONTENT
I
ANALYSIS BY WEIGHT OF TOTAL MIXTURE
CONTRACTOR: PALOMAR GRADING & PAVING
;AMPLE= ========> CLASS B MIXTURE DATE 02-Jun-94
DENTiFICATiON=> VISTA INDUSTRIAL ASPHALT
lix DESIGN==== =>
PALOMAR AIRPORT ROAD
/MA WAS CALCULATED USING= = = => BULK SPECIFIC GRAVITY
OMPOSITION OF PAVING MIXTURE: HVEEM
ONSiTITUENT SPECIFIC GRAVITY
I1ATERIAL
1.CRSE AGGT-GI- 58.0' 2.800
-
MIX COMPOSITION 0,'o BY
WEIGHT OF TOTAL MIX
55.854 55.564 55.274 54.984 54.694
2.FiNE AGGT-G2-
3.MiNL FLTR-G3-
42.0/ 2.700 40.446 40.236 40.026 39.816 39.606
0.000 0.000 0.000 0.000 0.000 0.000
4.TOTL AGGT-GS-
5.ASPTCEMT•GB-
2.757 PS. 96.300 95.800 95.300 94.800 94.300
1.015 PB- 3.700 4.200 4.700 5.200 5.700
6.BULK SP GR (GRB) TOTAL AGGT
7.MAX SP GR (GMM) PAVING MIX
8.BULK SP GR (GMB) CMPTD MIX
UNIT WEIGHT (#8 X 62.4)
9.EFFECTIVE SP GR (GSE) TOTAL AGGT
10.ABSD ASPLT (PBA%) BY WGT TOT AGGT
11.EFFECTIVE ASPLT CONTENT (PBE) .
12.VMA
13.AIR VOIDS (PA)
14.VOiDS FILLED
15.S-VALUE
16.SWELL
2.757 2.757 2.757 2.757 2.757
2.605 2.599 2.579 2.560 2.544
2.442 2.460 2.503 2.510 2.509
152.38 153.50 156.19 156.62 156.56
2.772 2.790 2.791 2.793 2.799
0.199 0.435 0.448 0.475 0.552
3.506 3.779 4.269 4.745 5.174
14.703 14.520 13.480 13.693 14.183
6.257 5.348 2.947 1.953 1.376
57.4 63.2 78.1 85.7 90.3
46.0 42.0 39.0 34.0 30.0
0.001 0.001 0.001 0.001 1 0.010
By
..........
R.CONSTRUCTIN MATERIALS LAB SUPERVISOR ASPHALT AND AC TES
PALOMAF1 AIflPOflT ROAD
B MIXTUflE
HVEEM
6 .L ......... ...............
AIR VOIDS I ......
4 ..
I I H
3.700 4 200 4.700 5.200 5.700
ASPHALT CONTENT
..UE
............/...................................
.............. ............
.. ............................. ...............
iN...........
3.700 4 200 4.700 5.200 5.700
ASPNAIT CONTENT
0.01
0.009
0.008
0.007
.L 0006
0.005
0.004
0.003
0.002
0.001
...... . ..............
..... .. 3.700 4.200 4.700 5 200 5.700
ASPHAI.T CONTENT
157
156.5
156
155.5 UNIT WOT III
154.5
151
153.1
153
152 5
152
S ?Oft 4 20O 4 700 Is O0 S 700
ASPHALT CONTENT
14.3
14.6
14.4
V U A 14.2
14
13.8
13.6
13.4 3.700 4.200 4.700 1.200 5.700
ASPHALT CONTENT