Primrose-CS 950523 817 277 0571
05/23,"95 11:04 9817 277 0571 AIG INC ~001/001
ARCHITECTS
INTERIORS
GRAPHICS
F A X(214) 304-3673
TO: ATUL PATEL/ CITY ENGINEER
PRIMROSE DAYCA~E/COPPELL
FROM: ODIS RAY / SENIOR VICE PRESIDENT
DATE: 05/22/95
NUMBER : 4 INCLUDING COVER
A.I.G. FAX NUMBER: (817) 277-0571
COMMENTS- PLEASE FIND ENCLOSED. LETTER FROM GEOTECHNICAJ_ CONSULTANTS
TO OMIT 6" LIME-STABILIZED BASE AT PARKING AREA. PLEASE
CALL ME AS SOON AS POSSIBLE TO LET ME KNOW IF THIS MEET
YOUR APPROVAL.
AIG, Inc. · 1527 Noffh Cooper Street · Suite 600 · Arlington, TX 76011 · Metro 817-265-:2415 · Fax 817-277-0571
05.'23,'95 11:04 9817 277 0571 AIG INC ~002/004
reed engineering
GI=O'rr=CHNICAL CONSULTAN'r~
Fay s, ;95 RECEIVED
Project No. 2291
1 2 1995
city of Coppell
255 Parkway Boulevard ~G
coppell, Texas 75019
ATTN: Hr. Ken Gr£ffith
City ~ngineer
Primrose S~hool
Heaz~z Boulevard and Parkway Boulevard
Coppell, Texas
Ge nt i ese n:
Submitted here are recommendation~ regarding equivalent pavement
sections for the referenced project. It is our understanding the
City of CoDpell ordinances require lime stabilization of both light
a~d hea~y pavement subg~ades.
The design section for light-duty pavement consists of 5 inches of
3,000 pounds per square inch (psi) concrete. Analysis indicates
this section will take unllmited repetitions of light car and truck
traffic. Lime stabilization below five-inch pavement within areas
subject to light-duty traffic is not requ~ed from an engineering
perspective.
The standard heavy-duty pavement was considered to consist of 6-
inch thick, 3,000-psi. compressive strength concrete over 6 inche~
of lime-stabilized subgrade. The analy~i~ has consisted of
determining the daily repetitions of an equivalent 18-kip axle load
and a 20-year ~eslgn life. The analysis followed procedures from
the American Association of State Highway Officials (AASHO) Interim
Guide. A copy of the AASHO design homograph is attached as Plate
1.
Three pavement sections have been analyze~; the referenced
"standard" pavement, 6 inche~ of 4,000-psi concrete, and 7 inches
of 3,O00-p-~i con~rete. The latter two sections were analyze4
considering natural or unstabilize~ subgrade.
2424 s'rUTZ DRIVE · SUITE 400 · DALLAS, TEXAS 7~'~ · 214/350-5600 · (FAX) 214/350-0019
05~23/95 11:05 9817 277 0571 AIG INC ~003/004
City of Coppell
Project No. 2291
Hay 8, 199~
Page 2
The first factor to be derived consists of the. modulus of ~bgrade
reaction, k, for both the natural subgrade and on top of a six-inch
layer of lime stabilized. A value of 100 pounds per cubic i~ch
(pci) is recommended for the natural subgrade.' Correlations
developed by the Federal Aviation Administration (FAA) for cement-
stabilized subgrade provide an effective k value, considering a
inch stabillzed subgrade of 210 poi. Two hundred pci was used for
the analysis. A copy of the FAA correlation ia attached aa Plate
T~e ~eco~d favor required to e~aiua~e the pave~t sactions
cons~sts/~i~She working stress of the concrete. This value
equal t~ 0.7/5 percent of the modulus of rupture (MR). Correlations
between%~h~compressive strength and ~R ~nd~cate that the
strength. This analysis result~ in a working stress of 370
psi for the 3,000-- and 4,000-p~i concrete, respectively.'~
Application of the AASHO nomograph resulta in the derived
equivalent 18-kip axle loads ~hown below.
Pav~.m_e~ _S_e_c~ion Equlvalent 1S--KiD Axle T.o~d~/Dav
6-i~ch, 3,000-psi concrete
over 6" l~me 40
6-inch, 4,000-psi concrete
over natural sutxFrade 40
7-inch, 3,000-psi concrete
over natural subgrade 70
As discussed above and ms shown on Plate 1, the allowable daily
traffic is based on a 20-year design life.
Based on this analysis, 6 inche~ of 4,000-p~i concrete over a non-
lime-~tabilized subgrade is the eq~/ivalent of 6 inchem of 3,000-pmi
concrete over 6 inches of lime-stabilized subgrade.
05;25/95 11:05 9817 277 0571 AIG INC ~004/004
City of Coppe11
Project No. 2291
May 8, 1995
Page 3
We trust t~is information is sufficient for your u~e. If any
questions arise, do not hesitate to call.
Sincerely,
REED ENG~_~G G~w INC.
RFR/apr
copies submitted= (2) City of Coppell/Mr. Ken Griffith
~(1) c/o A.I.G., In=./~r. Ken Reim~r