ST0501-LR120523 G • GEOTECHNICAL ENGINEERING
1,0?
E • ENVIRONMENTAL CONSULTING GEE Consultants, Inc.
E • CONSTRUCTION MATERIALS TESTING
10046 Monroe Drive • Dallas, Texas 75229 • (214)352-5433 • Fax(214)352-6972
May 23, 2012
Mr. George Marshall, P.E.
City of Coppell
Engineering Department
255 Parkway Blvd.
P.O. Box 9478
Coppell, Texas 75019
Via: gmarshall @coppelltx.gov
RE: Project No. 211-0125
Deforest Road Reconstruction
ST-05-01
Coppell, Texas
Dear Mr. Marshall,
Per your May 8, 2012 e-mail request, a representative of Texas CMT, Inc. performed visual
observations of pavement subgrade material at the above referenced project on May 11, 2012. The
purpose was to determine recommended limits of cement stabilization and to obtain four(4)samples
of exposed soils so that a cement series test on pavement subgrade could be performed. It is our
understanding an eight(8)inch thick layer of normally reinforced Portland cement concrete will be
utilized for a pavement wearing surface constructed over the stabilized subgrade layer.
The four(4)soil samples were transported to our laboratory and classification tests were performed.
The classification test results were as follows:
Sample Location Description Liquid Plastic Plasticity %Passing a No.
No. Limit Limit Index 200 US Sieve
1 S. Side Shoulder Dark Brown and Brown Sandy 22 18 4 27
at Inglenook Court Clay and Clayey Sand(Mix)
S. Side Shoulder Dark Brown Silty Sand and
2 at Stratford Lane Yellowish Brown Sandy Clay with 22 17 5 36
Asphalt Fragments(Mix)
S. Side Shoulder Brown and Reddish Brown Clayey
3 at Cambridge Sand 19 16 3 24
Manor Lane
City of Coppell
Deforest Road Reconstruction May 23,2012
Sample Location Description Liquid Plastic Plasticity %Passing a No.
No. Limit Limit Index 200 US Sieve
S. Side Shoulder Yellowish Brown Silty Sand and
4 at Castle Creek Light Gray and Yellowish Brown 23 16 7 35
Drive Sandy Clay with Gravel and
Asphalt Fragments
Based on the above listed classification test results,we conducted a cement series test on the above-
mentioned soil sample ft 4. The cement series test results are listed below:
CEMENT SERIES TEST
Cement%(by Dry Weight) Liquid Limit Plastic Limit Plasticity Index
0 26 16 7
3 25 24 1
5 NP NP NP
7 NP NP NP
NP-Non-Plastic
Based on the above test results,it is our recommendation that a minimum of six(6)percent cement
slurry(by dry weight)be added for stabilization of the proposed pavement subgrade soil. Based on
an estimated maximum dry unit weight of 110 pounds per cubic foot this would be equivalent to
approximately 39.6 pounds of cement per square yard for an eight (8) inch thick subgrade layer.
Cement stabilization should be performed beneath all proposed Portland cement concrete pavement,
medians,curbs and gutters between Stations 8+15 to 25+50 to a width of at least one(1)foot behind
the back of the curb,unless noted otherwise.Lime stabilization shall be utilized outside of this area
as per accepted plans and specifications.
If the soil binder-cement mixture contains clods,they should be reduced in size by raking, blading,
discing,harrowing,scarifying or the use of other approved pulverization methods. Clods should be
reduced in size so that when all non-slaking aggregates retained on the No.4 U.S.sieve are removed
after final mixing of the top six(6)inches the remainder of the soil,with cement mixed throughout,
should meet the following requirements when tested utilizing laboratory sieves at roadway moisture
content:
Texas CMT,Inc. Project No.211-0125
Page 2 of 3
City of Coppell
Deforest Road Reconstruction May 23,2012
Gradation Requirements for Top Six(6) Inches of Subgrade Soils
Mixed with Cement Slurry
(Texas DOT Soils and Aggregates Test Procedures Tex-101-E, Part III
and Texas DOT Standard Specifications Item 275.4)
Minimum Passing 1-3/4" Sieve 100 %
Minimum Passing 3/4" Sieve 85 %
Minimum Passing No. 4 Sieve 60%
Pavement subgrade should be adequately mixed with cement slurry, compacted and moisture
conditioned in accordance with accepted plans and specifications.We recommend the course should
be sprinkled or aerated in accordance with Texas DOT Standard Specifications Item 204 as required
and the top six(6) inches compacted to not less than 95 percent of the maximum dry density, and
within 2.0 percent below and 3.0 percent above the optimum moisture content as determined by the
Standard Proctor ASTM D 698 Moisture/Density Relationship test.
Gradation and density tests should be performed to verify adequate mixing and compaction in
accordance with accepted plans and specifications. After cement stabilization and shaping to
required grades and lines is completed the subgrade should be sealed with an emulsified asphalt at
a rate of 0.2 gallons per square yard,cured for a minimum of three(3) days and maintained at a
moisture content no less than two(2)percent below the optimum moisture content.
Our recommendations are based on the assumption that an adequately designed and constructed
Portland cement concrete wearing surface will be utilized. Drainage should be maintained away
from pavement sections both during and after construction.Ponding of water should not be allowed
at any location.
If you have any questions or if you require further information,please do not hesitate to contact us.
Sincerely,
Texas CMT,Inc.
TBPE Firm No. F-4521
0k Richard W. e °° y 'F
Project Engineer President
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cc. Mr.Dan DeGroot-Burgess&Niple,Inc:;Phone:972-620-1255;via E-mail: Dan.DeGroot @Burgessl ipie r pttt
Texas CMT,Inc. Project No.211-0125
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