ST9302-CS 990924ALPHA TESTING, INC.
2209 Wisconsin St., Suite 100
Dallas, Texas 75229
972/620-8911 - 972/263-4937 (Metro)
FAX: 972/406-8023
September 24, 1999
CITY OF COPPELL
255 Parkway Boulevard
Coppell, Texas 75019
Attention: Mr. Ken Griffin, P.E.
Re: Pavement Section Information
SANDY LAKE ROAD (WEST BOUND)
(Station 0+00 through 56+00)
Coppell Project No. ST-93-02
Coppell, Texas
ALPHA Report No. 98881-75
Provided below are results of our analysis of various pavement sections to be considered by the
City of Coppell for the new roadway referenced above. Analyses were preformed using
procedures outlined in the AASHTO Guide for Design of Pavement Structures (1986) and
considering different subgrade improvement methods. It is our understanding the new pavement
surface will consist of reinforced portland cement concrete supported a prepared subgrade.
Various improvement methods (lime stabilization and cement modification) were considered for
the subgrade as well as scarifying and re-compaction of the subgrade. Review of previous
sampling and testing of the exposed pavement subgrade indicates the subgrade generally consists
of clayey sand and/or sandy clay soil. During the analysis, a compressive strength 3000 psi at
28-days was assumed for the portland cement concrete pavement. A summary of the modulus of
subgrade reaction (k, pci) for the various subgrade conditions considered during the analysis are
tabulated below.
MODULUS OF
SUBGRADE MATERIAL SUBGRADE REACTION
(k, pci)
Scarified and Re-compacted 150
Subsrade
Lime Stabilized Subgrade 200
Cement Modified Subgrade 350
A lime stabilized subgrade would be achieved by mixing the soil with about 39 lbs of hydrated
lime (by dry soil weight) per sq yard of pavement subgrade treated while the cement modified
subgrade would be achieved by mixing the pavement subgrade soil with 32 lbs of cement per
square yard of treated area. The allowable 18-kip equivalent single axle load applications for
Geotechnical Engineering · Construction Materials Testing · Environmental Engineering · Consutfing
T ' T T
various portland cement concrete pavement sections supported on the above subgrade conditions
were calculated using the design procedures from AASHTO. Results of the allowable traffic
calculations are tabulated below:
PAVEMENT SECTION
8 inches of Reinforced Portland Cement
Concrete supported on 8 inches of Scarified
and Re-compacted Subgrade
8 inches of Reinforced Portland Cement
Concrete supported on 8 inches of Lime
Stabilized Subgrade
8 inches of Reinforced Portland Cement
Concrete supported on 8 inches of Cement
Modified Subgrade
9 inches of Reinforced Portland Cement
Concrete supported on 8 inches of Scarified
and Re-compacted Subgrade
ALLOWABLE 18-KIP EQUIVALENT
SINGLE AXLE LOAD APPLICATIONS
650,000
800,000
1,100,000
1,100,000
ALPHA TESTING, INC. appreciates the opportunity to be of service on this project.
be of further assistance, please contact our office.
Sincerely yours,
ALPHA TESTING, INC.
David A. Lewis, P.E.
er of Engineering Services
President
DAL/JLH/pc
Copies: (2) Client
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