during the spring thawing period. High pavement surfacedef1ection taken during this period confirmed this phenomenon. Implementation. Spring breakup exists ...
Report No. CDOH-DTD-R-88-1 1
SPRING BREAKUP STUDY
Ahmad Ardani Colorado Department of Highways 4201 East Arkansas Avenue Denver. Colorado 80222
Final Report April. 1988
Prepared in cooperation with the U.S. Department of Transportation Federal Highway Administration
The contents of this report reflect the views of the author who is responsible for the facts and the accuracy of the data presented herein.
The
contents do not necessarily reflect the official views of the Colorado Department of Highways or the Federal Highway Administration. does not constitute a standard, or regulation.
-ii-
This report
specification,
Technical Report Documentation Page 1. Report No .
3. Recipient 's Cctc lcg No.
2. Government Access ion No .
CDOH-DTD-R-88-11 4. Tit le ond Subtitle
5. Report Date
April 1988
spring Breakup study
6. Perform ing Organ i zation Code
17.03 (l485A)
8. Perform ing Organization Report No. 7. A",tfto'( . )
CDOH-DTD-R-88- 11
Ahmad Ardani 9. Performing Organ,ization Name and Add,ess
10. Work Unit No. (TR:AIS)
Colorado Department of Highways Division of Transportation Development 4201 E. Arkansas Avenue Denver t CO 80222
Ii. . Contract or Grant No .
13. Type of Report and Period Covered
12. Sponsoring Agency Nome and Address
Final Report 14 . Sponsorini A,.ncy Code
15. Suppl ......ntDl"Y Not.s
Prepared in cooperation with ·the u.s. Department of Transportation, Federal Highway Administration. 16. Ab.troct
The effect of an increase in moisture content of subgrade soil was evaluated on S.H. 131 in western Colorado. Dynaflect and moisture/temperature probes were used to obtain pavement surface deflections and subgrade moisture content. Analysis of the data obtained demonstrated that the load-carrying capacity of the pavement decreased rapidly as the moisture content was increased above the plastic limit (PL during the spring thawing period. High pavement surfacedef1ection taken during this period confirmed this phenomenon.
Implementation
Spring breakup exists and is costly. The results of this study have demonstrated the highway department's need to investigate the magnitude of spring breakup in Colorado and to take measures to alleviate such problems .
17. Key Wo,ds
18. Distrib",tion Statement
Thawing period Deflection Temperature 19. Security Closalf. (of this report)
Unclassified Form DOT F 1700.7
(8_72)
No restrictions: This report is available to the public through the National Technical Information service, Springfield, VA 22161
20. S.curity Clossif. (of this page)
Unclassified R.produc:tion of completed page authorized
- iii-
21. No. of Poges
37
22. Price
l694r TABLE OF CONTENTS SECTION
PAGE NO. I.
Introduction
1
Objectives
2
III.
Site Selection
3
IV.
Instrumentation
5
V.
Data Acquisition
11
VI.
Data Analysis . .
11
II.
VII . VIII. IX.
x.
A)
Deflection Variations
11
B)
Moisture Variations
15
C)
Temperature Variations
15
Load Restriction During Spring Thaw
15
Conclusions and Recommendations
18
Implementation
18
References
20
Appendix A
23
Appendix B
26
Appendix C
32
-iv-
LIST OF FIGURES
FIGURE NO.
PAGE NO.
1
Site Location . •
2
Profile of Trench Excavation
8
3
Deflection vs. Time-of-year .
13
4
Moisture Variation vs. Time-of-Year
14
5
Deflection vs. Moisture .
15
6
Temperature Variation vs. Time-of-Year
16
7
Temperature vs. Moisture:
Probe #1
18
8
Temperature vs. Moisture:
Probe #2
18
9
Temperature vs. Moisture:
Probe #3
19
10
Temperature vs. Moisture:
Probe #4
19
11
Typical Calibration Chart for MC 300A Moisture Meter
29
12
Resistance vs. Temperature
30
13
Moisture Resistance Curve
31
-v-
"
LIST OF PHOTOGRAPHS
PHOTO NO .
PAGE NO.
1
Typical Pavement Distress Caused by Spring Thaw
2
2
A Trench Dug By Backhoe
9
3
crowbar Used to Provide a Pilot Hole for the Soil Cell.
9
4
One-inch PVC Pipes Used to Protect the Lead Wires from Moisture and to Secure the Cell . .
5
Soil Cell Inserted Into the Pilot Hole Under the OUtside Edge of the Driving Lane . .
6
. . . . . 10 . . . . . 10
Backfill and Compaction Accomplished by a Front End Loader and Hand Tools
11
7
Typical Moisture/Temperature Cell . .
28
8
Battery-powered MC 300A Moisture Meter
28
-vi-
LIST OF TABLES
TABLE
TITLE
PAGE NO.
A
Temperature Characteristics
3
B
Soil Cell Log
6
C
Soil Log of Trench
6
D
spring Data Collection
33
Spring Data Collection (continued)
34
-vii-
I.
INTRODUCTION
Many asphalt pavements in Colorado suffer from annual spring thaw and breakup.
During the early spring and late winter, certain soils experience
an increase in moisture content and, consequently, a decrease in density. The increase in the moisture content of subgrade soil reduces the supporting capacity of pavement and results in a premature distress of pavement. Pavement distortion not only creates hazardous driving conditions for the motorist but maintaining them is also a costly operation.
One of the first
signs of spring breakup is the occurrence of alligator cracks, as shown in Photograph 1.
These kind of cracks, which result from subgrade softening,
eventually turn into chuckholes. II.
OBJECTIVES
The primary objectives of this study were: a.
To establish a data base using the variables of pavement surface
deflections, subgrade moisture contents, subgrade temperature, and climatic data. b.
To predict seasonal changes within the pavement structure, and
incorporate the results into proposed load restrictions during the critical time of the year . III.
SITE SELECTION
The following criteria was used in order to locate a test site for this project: 1.
The study site must be located in an area of potential deep frost.
2.
The pavement surface must indicate signs typical of spring breakup (alligator cracking and chuckholes).
3.
There should be a presence of heavy truck traffic.
Photograph 1:
A typical pavement distress caused by spring thaw.
- 2-
4.
Frost susceptible soil (materials which have an affinity for moisture) should be present.
5.
The draina&e system should be in poor condition.
Based on the above criteria, a site was selected on S. H. 36, near the town of Last Chance, 80 miles east of Denver.
This site lies on a &ently
rollin& terrain with an elevation of 5300 feet.
The avera&e annual
precipitation is 15 . 6 inches, and the total yearly snowfall is 31 inches. This site was evaluated for a period of two winters; however, because of the severe temperature fluctuation (freeze-thaw cycles) experienced in the area, no conclusive results were obtained. A second site with a colder climate was se lected on S.H. 131 north of Wolcott, approximately 140 miles west of Denver (Figure 1).
This site is
situated on mountainous terrain with an elevation of 6700 feet .
The average
daily traffic (ADT) at this location is 1000 with 11 percent of that consisting of truck traffic.
The average annual precipitation is
12.1 inches, and the total yearly snowfall is 31 inches.
The following table
shows the temperature characteristics of this area: TABLE A TEMPERATURE CHARACTERISTICS
Days per Year with Temperatures of . . . High of
High of
Low of
gO°F or More
32°F or Less
32°F or Les s
15
Source:
28
214
Colorado Cl i mate (state climatolo&ist) -3-
Low of oaF
or Less 28
Years of Data 13
SITE LOCATION I
i
FlO UTr
r.J .J
Hoyden
Loy
@
LAFI J};JE
~ilner
"Meeker
EAGLE
Collbran
/@
Redstone
"
- - - - ......
?AFlK ®
"
'\
.
'-- '
• ..J'
/
. -~.
..... 1 _
\
-'-. I • ....aueno Vista J
!
Sopiroero
~ , - , -,-, \ n. ,"" \
r------
I I I I
'-'-'-'"1 SDALEi J-J J N
-4-
The particle size distribution determined by a sieve analysis revealed a subgrade which was predominantly clay, A-7-6(12) with moderate to negligible amounts of coarse material . size chart and index properties.)
(Appendix A shows the typical grain
Even though the flow of gravitational
water is very slow for this type of soil, the capillary pressure that causes moisture to move from the wetter to the drier portions is very great and 1 large expansion can be developed. IV.
Instrumentation The soil test MC-300A moisture/temperature meter was used to obtain
moisture and temperature of the subgrade for this project.
The following is
a summary of the instrument description and instrument installation: A.
Instrument Description A thorough description of the instrument used for this project
can be found in Appendix B. B.
Instrument Installation On September 6, 1986, four moisture/temperature cells (probes)
were installed on S.H. 131 north of Wolcott at a predetermined location in the southbound lane at milepost 11.2 Installation of the cells began with an excavation of a trench 2' wide, 4' deep, and 10' long (Figure 2).
A gas-powered chisel was
used to outline the pavement surface, and a backhoe to remove the material.
To protect the cell's leads from being exposed to moisture,
I" PVC pipes were used, and cells were then glued to the end of them. Using a crowbar, pilot holes were punched into the vertical face of the trench at the outside edge of the driving lane.
The sharp cell
edge was then forced into undisturbed material at 10-12 inches intervals from the bottom of the trench.
The trench was backfilled
and compaction was obtained by hand tool s and by using the backhoe bucket.
Table B shows the location of the cells and their -5-
corresponding depth, and Table C shows the soil log of the trench for various layers.
Photographs 2 through 5 demonstrate parts of the soil
cell's installation.
-6-
TABLE B SOIL CELL LOG
Soil
Te!!!I!erature
Cell
Coefficient
Number
Depth
Factor
1
45.6"
0.99
1
36.0"
1.00
3
26.0"
1.00
4
10.0"
1.00
TABLE C SOIL LOG OF TRENCH
Description Asphalt mat
0_6'"
6-46"
*C1ay of high plasticity index with occasional gravel
-7-
FIGURE 2 PROFILE OF TRENCH EXCAVATION
I
I Ex cavated Tr ench
24"
~,:-- - - - - -, Cf.
T
II ASPhalt _~
2' Shoulder
,
~
I
r
PLAN VIEW
12' N.B . Lane
~~
2' Asphalt Shoulder
L
~I
12' S.B. Lane RIVP
4'_""
Cf.
I I
CROSS
SECTIO~
-8-
L_
- _ __ J
~
1I
Photograph 2:
Using the Department's backhoe, a trench was dug.
Photograph 3:
A crow bar was used to provide a pilot hole for the soil cell.
-9-
Photograph 4:
One··inch PVC pipes were used to protect the lead wires from moisture and to secure the cell.
"~'ff:' -
";'•.:'"''':~'''
Photograph 5 :
The soil cell was inserted into the pilot hole under the outside edge of the driving lane. -10-
Photograph 6:
Backfill and compaction was accomplished by the use of a front end loader and hand tools.
-11-
V.
DATA ACQUISITION Field data was collected for a period of seven months beginning in
February and ending in September 1987 .
The following types of data were
collected: .pavement surface temperature oambient air temperature osubgrade temperature osubgrade moisture content opavement surface deflections using dynaflect Prior to the above data collection, samples of subgrade materials were obtained in order to calibrate the soil cells for moisture content determination (Appendix B). basis.
The above data were collected on a biweekly
The deflection data were obtained on ten-foot intervals for 10 points
and then averaged.
A special device called the "Wahl Heat Spy" infrared
thermometer was used to obtain pavement surface temperatures.
A MC 300A
moisture/temperature meter was used to acquire moisture and temperature data from the soil cells. VI.
Air temperature data was collected by a thermometer .
DATA ANALYSIS The following is the summary of the data analyzed in this study: A.
Deflection Variations The graph plotting the average deflection data versus the time of
the year is shown in Figure 3.
According to this figure, early spring
was the period of highest deflection (March 4 through March 26).
The
lowest deflections were detected during February, indicating a frozen subgrade.
Deflection data acquired between April and September showed
continued recovery of the pavement strength.
-12-
FIGUR E 3 DEFLECTION VS. TIME-OF-YEAR 6 -r------------------------------------------------------------------, 5 .5 5
4.5 ,-... UJ ...J
L
4
'" Z
I ~
'-" I
0 f=
3 .5
0
W
...J .... W
3
a
2.5
2 1.5
1 FE812
23
MAR4
12
18
26
APR2
10
TIME-OF-YEAR
15
22
29
MAY13
27
JUN17SEP15
FIGURE 4 MOISTURE VARIAllON VS. llME-O F-YEAR 34 32 30 28 26 r-.
~
24
I-
22
'-'
Z
W
, -"",
I-
Z
0
()
w
20 18
a:
16
I-
14
::l
til
0
~
12 10
8 Q
4 2 FEB12
o
23
DEPTH
MAR4 45.6"
12
18
+
26 DEPTH
APR2
10
TIME-OF-YEAR 36"
15
22
DEPTH
29
26"
MAY13
t:.
27
JUN1 7SEP15
DEPTH
10"
F IGURE
5
DEFLECTION VS MOI STURE SH 131
AT WOLCOTT
~ I
-cf?
?
30
.....-
I
-
\ Jl
I
w rr
:J
r(j)
0
./
0
20
I
/
0
Y=1B.7LnX+7.3
/
2
r=0.B6
10 0
0
I 0
0
I 1
2
3
4
DEFLECTION (MILS)
5
6
7
FIGUR E 6 TEMPERATURE VARIAT ION VS. TIM E-O F-Y EAR
80 -,------------------------------------------------------------------,
70
".....
lJ...
r3 w
60
0
'-" I
W
~
(t
0> I
:J
50
~
(t
W D..
2:
w
r-
40
30
20
-Ir---.---,----,---,----r---,----,---,---,----r---,----,---,--~
FEB12
D
23
DEPTH
MAR4
45.6"
12
18
+
26
DEPTH
APR2
10
TIME-OF-YEAR 36" 0
15
22
DEPTH
29
26"
MAY13
t:,
27
JUN17 SEP1 5
DEPTH
10"
B.
Moisture Variations Fisure 4 shows the variation of subsrade moisture content at
various depths from February throush September.
The subsrade at the
depth of 10" and 26" showed the hishest moisture content and the hishest variation.
The increase in soil moisture was most sisnificant
durins the sprins thawins period (the month of March) for the probe at the 10" depth.
The probe at the 26" depth also showed a very sharp
increase in moisture content between March 4 and March 18.
However,
this probe showed continued increase in moisture throush May 13.
The
probes at the depth of 45.6" and 41" exhibited the least variations throushout the entire period.
All the probes showed the same moisture
content (approximately 23 percent) by mid-september indicatins an almost consolidated subsrade.
The sharp increase of the subgrade
moisture content in early March correlated well with the surface deflections for the same period.
The moisture content of the subgrade
at the 10" depth was 11 percent higher than the plastic limit indicatins a very soft subgrade.
The plastic limit (PL) of the
subsrade at this site was 22 percent, while the moisture content was 33 percent.
Figure 5 shows the relationship between moisture content
of the subsrade at the 10" depth and the pavement surface deflection. Inspection of the data plotted in Figure 5 indicated a logarithmic relationship with a fairly sood fit. C.
Temperature Variations The temperature variations for all four probes are shown in
Fisure 6.
Figures 7 through 10 were developed to study the
relationship between temperature and moisture content of the subgrade at various depths.
However, no conclusive results were obtained.
complete record of temperature, moisture, and their corresponding deflections can be found in Appendix c.
-17-
A
FIGURE 7 TEMPERATURE VS MOISTURE (DEPTH -1-5.6")
25 0
24.5 24 -
0 0
0 0
23.5 -
0
0
~
K
~
w
23 -
Iii
22.5 -
0
0
5
0
::;,
22 21. 5 21
0
0
,0
20.5
,
25
35
55
45
65
TEMPERATURE DEG.F
FIGURE 8 TEMPERATURE VS MOISTURE (DEPTH 36") 26 .-----------------------------~----~--a_------------_;
25 0
24 -
0
~
0
0
K
~
0
w
23 -
0
0
Iii 5
0
::;,
22 -
21 -
o 20
o 0
~------._,------r_-----._,------._----_,,_----_,------_r------~
25
35
55 TEMPERATURE DEG.F
-18-
65
FIGURE 9 TEMPERATURE VS MOISTURE (DEPTH 20") 30 0
2B -
[J
0 0
26 0
0
24 -
0
0
D
22 20 ~
I< ~
w ~
1B -
:::>
16 -
5
14 -
t?
:E
12 10 [J
B6 4
0
0
,
,
35
45
2 25
,
,
,
55
65
TE MP ERATURE OEG.F
FIGU RE 10 TEMPERATURE VS MOISTURE (DEPTH 10") 34
30 -
B
0
32 0
[J
0
[J
0 [J
[J
2B 26 0
D
24 ~
I
t?
1B -
:E
16 -
5
14 12 10 B-
0
6
,
4 25
, 35
45
TEMPERATUR E OEG.F
-1 9-
55
65
VII .
LOAD RESTRICTION DURING SPRING THAW A report was developed by the Washington State Transportation Center
and the University of Washington to predict seasonal changes within the pavement structure, and to restrict heavy loads during the critical time of the year.
This report, "Guidelines for Spring Highway Use Restrictions" uses
the thawing and freezing index to estimate when and where to apply and remove load restrictions.
A summary of this guideline can be found in Appendix D.
In addition to the guideline, there is a supplemental videotape which can be obtained from the R&D Report Center (HRO-1l). VIII.
CONCLUSIONS AND RECOMMENDATIONS 1.
Analysis of the data taken in this study demonstrated that the load-carrying capacity of the pavement structure decreased rapidly during the spring thawing period.
Deflection data and
subgrade moisture content acquired at various depths showed a sharp increase during this period.
However, the soil moisture
content within the top layer of the subgrade showed the best correlation with surface deflections.
The moisture content for
this layer increased to a high of 32 percent, approximately 13 percent over the optimum moisture content. 2.
No conclusive relation was established between subgrade temperature and surface deflections.
3.
The moisture content of the subgrade and the deflection data can be used in assuring the need for load restrictions.
4.
Severe temperature fluctuations in Colorado from one day to another makes it difficult to clearly predict the beginning of the thawing period.
-20-
IX.
IMPLEMENTATION
The results of this study has demonstrated the need for controlling pavement distress during the spring thawing period .
Premature distress of
pavement on Colorado's highways can be attributed, in part, to the loss of supporting capacity during the spring thawing period.
It is recommended that
CDOH maintenance and materials engineers initiate a program to survey and identify highways associated with spring breakup and take measures to alleviate such problems. Incorporating the application of dynaflect and temperature/moisture probes into load restrictions appears to be the best criterion; however, they are expensive to obtain, especially on a statewide basis . It is recommended that moisture content within a few inches of the surface of the subgrade be used as the only criterion to apply or remove load restrictions.
As with any criterion, judgement must be used.
A load limit
may be applied when the moisture content increases by approximately 5 percent over the optimum moisture.
Depending upon the index properties of the
subgrade, higher or lower threshhold may be used.
-21-
x.
REFERENCES
Cheney, R. S., and R. G. Chassia. Manual.
Washington, D.C.:
Soils and Foundation Workshop U.S. Department of
Transportation, Federal Highway Administration, November 1982. Craig, R.F. Kingdom:
Soil Mechanics, 2d ed.
University of Dundee, United
Department of Civil Engineering, 1978.
Eres Consultants, Inc.
Pavement Design.
1986 .
Mahoney, J. P., and J. A. Lary, J. Sherman, N. Jackson.
An
Investigation of Seasonal Load Restriction in Washington State.
July 1984.
Portland Cement Association.
Soil Primer.
Sowers, G. B., and F. B. Sowers. Foundations, 3d ed.
1970.
-22-
1962.
Introductory Soil Mechanics and
APPUD[J[ 01.
_ 23 _
*************************************************************** MOISTURE-DENSITY CURVE
Compaction
T99
A.I1AD - RESEARCH Field Sheet #
Gradations: -4 Material #4 100 . #10 95 . #40 88. #200 64.2 Liquid Limit
Test #
% Passing
41.
Total Sample 95. #4 90. #10 84. #40 #200 61.0 Plasticity Index
22.
--------------------------------------------------------------optimum Moisture
18.1
Maximum Dry Density
-4 Material Class:A-7-6(12 )
105.3
Total Sample Class:A-7-6 (1l)
% H2O
Dry Density
% H2O
Dry Density
% H2O
Dry Density
15.1 15.2 15.3 15.4 15.5 15.6 15.7 15.8 15.9 16.0 16.1 16.2 16.3 16.4 16.5 16.6 16.7 16.8 16.9 17 .0
103.8 103.9 104.0 104.1 104.2 104.3 104.3 104.4 104.5 104.6 104.6 104.7 104.7 104.8 104.9 104.9 104.9 105.0 105,0 105.1
17.1 17.2 17.3 17.4 17.5 17.6 17.7 17.8 17.9 18.0 18.1 18.2 18.3 18.4 18.5 18.6 18.7 18.8 18.9 19.0
105.1 105.1 105.2 105.2 105.2 105.2 105.2 105.2 105.3 105.3 105.3 105.3 105.3 105.2 105.2 105.2 105.2 105.2 105.2 105.1
19.1 19.2 19.3 19.4 19.5 19.6 19.7 19.8 19.9 20.0 20.1 20.2 20.3 20.4 20.5 20.6 20.7 20.8 20.9 21.0
105.1 105.1 105.0 105.0 104.9 104.9 104.9 104.8 104.7 104.7 104.6 104.6 104.5 104.4 104.3 104.3 104.2 104.1 104.0 103.9
***************************************************************
Appendix A -24-
=
o
'" "o
>-
'"oc..
~ H-+-+++-l ." A ~ o '
;;
f-L
nl',JOM. ~ lIl ..U IN]:> 1001
- 25-
'"
~1~ w
w
'"
APPEIIOIJ: B
- 26-
APPENDIX B
Instrument Description: To monitor the temperature and moisture content of the subgrade, soil cells were used.
These cells are made up of two plates separated by a
processed fiberglass binding which provides a coupling which varies with the moisture content of the surrounding medium.
A small thermistor completes
this two-circuit unit. The standard soil cell is supplied with color-coded leads:
white for the
thermistor, red for moisture, and black for the lead common to the two. Photograph 1 shows a typical moisture/temperature cell. The battery-powered MC 300A moisture meter (Photograph 8) is used to acquire moisture and temperature data from the soil cells.
Model KC-300A is
a 90 cycle AC type ohmmeter with dial readings from 0 to 200.
The resistance
in ohms, corresponding to any dial reading, is determined by reference to the calibration chart shown in Figure 10.
Low scales, which has an effective
range from 50 to 10,000 ohms is used for the measurement of thermistor resistance.
Both scales may be used for the measurement of moisture
resistance.
The temperature is easily obtained by referring to Figure 11.
However, for obtaining the percent moisture content, soil cells must be first calibrated.
Individual cells are placed in soil samples of known moisture
content, and resistance readings are obtained for various moisture contents. A plot of these readings results in a graph that can be used at some later time to determine field moisture.
Figure 12 represents the calibration curve
for SH 131 north of Wolcott.
-27-
Photograph 7: Typical moisture! temperature cell
"'4 "
Photograph 8: Battery-powered Me 300A Moisture! Temperature Meter
-28-
10~
" r" 10~
.5
10
w • zu lO c{
I-
-
Ul Ul
w
,
a::
I
10
-
--
,
-
10
-
-
-
,
II
10
0
20
40
60 8 100 120 DIAL READIN G
FIGURE
140 160 180 20 o
'\0
Typical calibration chart for MC-300A Moisture Meter - 29-
Calibration Chart
.FIGURE
11
Resistance VS. Temperature -30-
F IGURE
12
MOISTURE RES IST A i'JCE CURVE 1 000000 ~F------------------------------------------------'
100000 ~~ (j)
10000
E
~
o
~
I
~ I
o
1000
(l)
0
C
cD
+-'
100
U)
U)
(l) L
10 1
0.1 6
8
11
13
15 17
19 2 2 24 26 28 30 32 3 4
soi ! moisture (%)
APPItNOIl C
- 32-
APPENDIX C
FILE # 17 . 03 AHMAD ARD'ANI
SPRING DATA COLLECTION WOLCOTT COLORADO TEMP . DEG.F
TEMP . DIAL
TEMP. OHMS
1 2 3 4
105 100 92 98
3000 3400 4000
35 31 25
3600
1 2 3 4
100 95 90 95
1 2 3 4
CELL #
MOST., DIAL
MOST . OHMS
%
MOST .
DEFL. MILS DATE
.
30
75 66 4 8
5500 7000 150000 70800
21 20.6 3.5 8
136 2-12-87 136 136 136
3400 3800 4200 3800
31 27 23 27
68 68 4 5
7000 7.000 150000 130000
20.6 20.6 3.5 4
117 2-23-87 117 117 117
102 97 97 95
3200 3750 3750 3800
33 27 27 27
75 72 10 115
5500 6200 75000 2500
21 20.8 9 25
173 173 173 173
1 2 3 4
100 100 95 95
3400 34 0 0 3800 3800
31 31 27 27
105 100 107 170
3000 3400 2900 620
23.6 23 . 1 24 32.5
553 3-12-87 553 553 553
1 2 3 4
105 100 100 100
3000 3400 3400 3400
35 31 31 31
105 98 115 140
3000 3500 2500 1500
23.6 23 25 30.4
404 3-18-87 404 404 404
1 2 3 4
100 105
3400 3000 3000 3000
31 35 35 35
97 97 115 140
3750 3750 2500 1500
22.5 22 . 5 25 30.4
372 3-26-87 372 372 372
1 2 3 4
107 102 104 • 111
2900 3200 3100 2700
26 33 34 38
99 102 115 142
3400 3200 2500 1400
23. 1 23.3 25
294 294 294 294
1 2 3 4
112 115 112 110
2600 2500 2600 2700
40 41 40 38
100 105 117 110
3400 3000 2400 2700
lOB lOB
,
- 33-
, t
30.B 23.1
23.B 26 24.5
3-4-87
.
4-2-87
326 4-10 - 87 326 326 326
,TEMP. DEG.F
MOST . DIAL
MOST . OHMS
MOST .
DEFL . MILS DATE
40 36 41 46
105 105 121 164
3000 3000 2200 750
23.6 23 . 6 27 32
334 4-15-87 .. 334 334 _334
2600 2250 2200 2000
40 45 46 50
107 107 121 172
2900 2900 2200 580
24 24 27 32.6
301 4-22-87 301 301 301
125 120 125 125
2000 2200 2000 2000
50 46 50 50
113 114 125 164
2600 2600 2000 750
24.7 24.7 28 32
303 4-29-87 303 303 303
1 2 3 4
130 130 130 135
1750 1750 1750 1600
54 54 54 58
113 117 129 150
2600 2400 1800 1100
24.7 26 30 31. 3
341 5-13-87 341 341 341
1 2 3 4
130 125 135 130
1750 2000 1600 1750
54 50 58 54
110 117 128 165
2700 2400 1900 730
24.5 26 29 32.3
318 5-27-87 318 318 318
1 2 3 4
100 140 145 150
3400 1500 1200 1100
61 60 69 72
115 105 120 140
2500 3000 2200 1500
25 23.6 27 30.4
270 6-17-87 270 270 270
1
135
2 3 4
130 135
1600 1750 1750 1600
58 54 54 58
95 100 100 100
3800 3400 3400 3400
22.3 23.1 23.1 23.1
240 9-15-87 240 240 240
TEMP. DIAL
TEMP . OHMS
1 2 3 4
113 107 116 120
2600 2900 2500 2200
1 2 3 4
114 119 120 124
1 2 3 4
CELL
II
1~0
-34-
%
.
mEllDIX n
_3.5_
GUIDELINES FOR SPRING HIGHWAY USE RESTR~CTIONS
Research, Development, and Technology
Turner-Fairbank Highway Research Center 6300 Georgetown Pike McLean, Virginia 22101·2296 Report No: FHWA- T5-87-200
u.s. Department of Transportation
Video Suppleme nt January 1987
Federal Highway Administration
. datumtnt is
hitll~bl'ID
the
u.s. public Ihrough th, N~tron.1 Tlchnic.allnformation Senortl , SPfl nljlfl.ld . VIfI~IMI 22161
SUMMARY OF GUIDELINES FOR SPRING HIGHWAY USE RESTRICTIONS
Where to apply: 1.
Surface thickness < 2 inches
2.
Type of subgrade (silts & clays)
3.
Pavement distress (alligator cracking & rutting)
4.
Surface deflections (surface deflections of 45 to 50 percent higher during spring than during summer .
Amount of restriction: "General national practice is to use load reductions ranging from 40 to 50 percent." When to apply: When the thawing index reaches : a)
Should level 10 to 25 degree days
b)
Must level 40 to 50 degree days
Duration of load restrictions: The load restriction should last until complete thawing is achieved. Complete thawing can be obtained through 2 equations: 1.
TI
2.
TI
4.15
= 0.3
+
0.26 (Freezing Index)
(Freezing Index)
-37 -
