Ridgecrest-CS130206From:9727139111
02113/2013 16:19 #515 P.0021004
February 13, 2013
Colin W. Helffrich, P. E.
Dowdey, Anderson & Associates, Inc.
5225 Village Creek Drive, Suite 200
Plano, Texas 75093
Re: Pavement Recommendation
Ridgecrest Estates Residential Development
Coppell, Texas
BCS Project Number: 123 -005 (Revised)
Dear Mr. Helffrich:
As requested, Bryant Consulting Services (BCS) has evaluated rigid pavement
(concrete) for the proposed residential development roadways on a 6 -inch cement
stabilized subgrade.
Suburade Modification Recommendation
BCS assumed a modified subgrade minimum unconfined compressive strength of
160 psi, which is commonly used in this area. Laboratory unconfined compressive
strength tests were performed on cement modified subgrade soils (3%, 40/6, 5% and 6%
cement molded at approximate optimum moisture). Due to time constraints, BCS based
our results on a 3 -day curing period and unconfined compressive strength, rather than
the normal 7 -days used for cement. Since the 7-day unconfined compressive strength
will exceed the 3 -day strength, it is BCS's opinion that a compliant 3 -day break is
suitable and adequate.
Based on our test results, BCS recommends applying 4% cement by weight to stabilize
the subgrade under roads at the subdivision. The results of our unconfined compressive
strength testing at the recommended 4% cement are provided to the moderate brown
silty clayey sand material (sample L -3) and grayish brown sandy clay material (sample
L -6) are provided in Table 1 (next page). In addition, the table provides our
recommended cement application rate in pounds per square yard (PSY).
Bryant Consulting Services, LLC
3360 Wiley Post Road, Suite 100 - Carrollton, Texas 76006
Phone: 972.713.9109 • Fax: 972.713.9171 • TX Firm Registration: F -11264
www.bryantconsultingservices.com - HUB Certified
From:9727139171
Ridgecrest Estates
Pavement Recommendation
Coppell, Texas
02/13/2013 16:19 #515 P.003 /004
TABLE 1 — 4% CEMENT SUBGRADE STABILIZATteM TFCT Q=Q11111 Tc
Page 2
The cement should be thoroughly mixed and blended with the top 6 inches of the
subgrade soil under the roadway. The cement stabilization should extend a minimum of
1 foot beyond the width of the roads on both sides, or extend the minimum distance
required by the City of Coppell, whichever is greater. The cement modified soil
subgrade should be compacted to a minimum of 95 percent of ASTM D 698, at a
minimum of +2 percent of the soils optimum moisture content determined by that test.
Density testing should be performed on the same day as final compaction. BCS should
collect representative samples of the cement stabilized material immediately after
mixing the mold and test.
Pavement Design
The designs were analyzed using AASHTO procedures, and the criterion for the
residential pavement section includes a 20 -year design life, 0% growth, and a maximum
Annual Equivalent Single Axle Load (ESAL) 50,000.
The following parameters were used in the below preliminary pavement analysis:
3,600 PSI Concrete
Concrete Section Thickness
Initial Serviceability, p°
Terminal Serviceability, pt
Reliability, R
Overall Standard Deviation
Overall Drainage Coef., Cd
Load Transfer Coefficient, J
Mod. of Sub. Reaction, k
28-day Conc. Mod. of Rupture
28 -day Elastic Mod. of Rupture
Design Life
SCI Project 125 -005
6 Inches
4.5
2.5
85%
0.34
0.7
3.2
250 psi /in
450 psi
3,600,000 psi
20 years +0%
Bryant Consulting services, LLC •- Confidential / Copyright ® 2013
:o n ed.
164 •
FModerate
Brown
Silty Clayey Sand
L -3
120.2
4°16
190
22
Grayish Brown
Sandy Clay
L -6
113.4
4%
222
22
The cement should be thoroughly mixed and blended with the top 6 inches of the
subgrade soil under the roadway. The cement stabilization should extend a minimum of
1 foot beyond the width of the roads on both sides, or extend the minimum distance
required by the City of Coppell, whichever is greater. The cement modified soil
subgrade should be compacted to a minimum of 95 percent of ASTM D 698, at a
minimum of +2 percent of the soils optimum moisture content determined by that test.
Density testing should be performed on the same day as final compaction. BCS should
collect representative samples of the cement stabilized material immediately after
mixing the mold and test.
Pavement Design
The designs were analyzed using AASHTO procedures, and the criterion for the
residential pavement section includes a 20 -year design life, 0% growth, and a maximum
Annual Equivalent Single Axle Load (ESAL) 50,000.
The following parameters were used in the below preliminary pavement analysis:
3,600 PSI Concrete
Concrete Section Thickness
Initial Serviceability, p°
Terminal Serviceability, pt
Reliability, R
Overall Standard Deviation
Overall Drainage Coef., Cd
Load Transfer Coefficient, J
Mod. of Sub. Reaction, k
28-day Conc. Mod. of Rupture
28 -day Elastic Mod. of Rupture
Design Life
SCI Project 125 -005
6 Inches
4.5
2.5
85%
0.34
0.7
3.2
250 psi /in
450 psi
3,600,000 psi
20 years +0%
Bryant Consulting services, LLC •- Confidential / Copyright ® 2013
From:9727139171
Ridgeereat Estates
Pavement Recommendation
Coppell, Texas
02/13/2013 16:20 #1515 P.004I004
Page 2
Based on the above parameters, the analysis yielded an 18 -kip Equivalent Single Axle
Load (ESAL) of 252 daily repetitions (63 Fully Loaded) for a 6 -inch section of
PCC pavement.
The analysis assumed that the 3,600 PSI concrete pavement is placed on a 6 -inch
cement stabilized subgrade as discussed above.
If. during the course of this project we can be of further assistance, please do not
hesitate to contact us.
Sincerely,
BRYANT CONSUL
TX FIRM REa18TRATl[�
Confldentlal / Coavrldfit
Brent L. u as, P.E.
Vice Prokidedit
Sandip Tamrakar, E.I.T.
Graduate Engineer
,SERVICES LLC
' -11204 s
2013 —0„�►V►ttt�t
cc: Larry Jackson, David Weekley Homes
BCI Project 125 -006 Bryant consulting Services, LLC — Confldentiat / Co
pyright ®2013
February 6, 2013
Colin W. Helffrich, P.E.
Dowdey, Anderson & Associates, Inc.
5225 Village Creek Drive, Suite 200
Plano, Texas 75093
Re: Pavement Recommendation
Ridgecrest Estates Residential Development
Coppell, Texas
BCS Project Number: 12S -005
Dear Mr. Helffrich:
As requested, Bryant Consulting Services (BCS) has evaluated rigid pavement
(concrete) for the proposed residential development roadways on compacted native
soils with no subgrade improvement.
The designs were analyzed using AASHTO procedures and the criterion for the
residential pavement section includes a 25 -year design life, 0% growth, and a maximum
Annual Equivalent Single Axle Load (ESAL) 50,000.
The following parameters were used in the below preliminary pavement analysis:
3,600 PSI Concrete
Concrete Section Thickness
8 inches
Initial Serviceability, po
4.5
Terminal Serviceability, pt
2.5
Reliability, R
85%
Overall Standard Deviation
0.34
Overall Drainage Coef., Cd
0.7
Load Transfer Coefficient, J
3.2
Mod. of Sub. Reaction, k
72 psi/ in
28 -day Conc. Mod. of Rupture
450 psi
28 -day Elastic Mod. of Rupture
3,600,000 psi
Design Life
25 years +0%
Bryant Consulting Services, LLC
3360 Wiley Post Road, Suite 100 • Carrollton, Texas 75006
Phone: 972.713.9109 • Fax: 972.713.9171 • TX Firm Registration: F -11264
vnAaw .bryantconsultingservices.com , HUB Certified
Ridgecrest Estates
Pavement Recommendation
Coppell, Texas
Page 2
Based on the above parameters, the analysis yielded an 18 -kip Equivalent Single Axle
Load (ESAL) of 252 daily repetitions (63 Fully Loaded) for an 8 -inch section of PCC
pavement.
The analysis assumed that the 3,600 PSI concrete pavement is placed on an
unmodified subgrade.
It has been a pleasure to perform this work for you. If, during the course of this project
we can be of further assistance, please do not hesitate to call.
Sincerely,
BRYANT CONSULTING SERVICES LLC
TX FIRM REGISTRATION NO.: F -11264
Confidential 1 C yr g r3��►,��ut�ttt
~PEE OF »f�
* • ........
. D A'
GL
�...... .....,..,
Brent L. Dougla , P. rtr A °• 98065
ViCePresid t sjo�AtPN
tt�ttit���~'`
Sandip Tamrakar, E.I.T.
Graduate Engineer
BCI Project 12S -005 Bryant Consulting Services, LLC — Confidential I Copyright cQ 2013
I
U
U
C
N 0
U
ro
U
0
N
N
od 1,0'
C
0
N
Q
0
0
U
U
L
U
llp
O
N
co
a' cinrwai 1r TI) Pr
CONSTRUCTED BY
c HOMEBUILDER
N
h
N
n
J
W
LL
It
W
W
n
m
N
O
Q
a
co
N
O
N
0
4'
50' ROW
10 0' 30' b —b
5 SAWED LONGITUDINAL ij ROW
DUMMY JOINT WITH
APPR0VED SEALER I
2%
12"
4"
COMPACTED SUBGRADE
TO A DENSITY NOT LES
THAN 95Z STANDARD
PROCTOR DENSITY
6" MOUNTABLE
CURB 7
6" PARABOLIC
CROWN
3
Q
10.0'
5' I 4' 1.0'
29'
12"
8" THK 3600 PSI CONC PANT
W/ NO 4 BARS 18" 0.0 E W.
TYPICAL PAVEMENT SECTION
N.T.S.