Geo tech project laboratory tests question - soil engineering

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Florida Department of Transportation

RICK SCOTT

GOVERNOR

S T A T E M A T E R I A L S O F F I C E 5007 Northeast 39th Avenue, Gainesville, Florida 32609

Telephone: (352) 955-6600, Fax: (352) 955-6613

ANANTH PRASAD, P.E.

SECRETARY

MEMORANDUM

DATE: April 17, 2013

TO: Michael Kim

FROM: David Horhota

SUBJECT: Embankment Resilient Modulus Pavement Design

District 6, Miami-Dade County

FPN 430637-1: SR-847/NW 47th Avenue from SR-860/NW 183rd Street to Premier Parkway

Five (5), 2-bag samples were received by the State Materials Office (SMO) for determination of an

embankment (roadbed) resilient modulus for pavement design. After visual observation of the 5 samples, it was

determined that the material from each sample looked visually similar and the material from each of the bags

were combined to form one sample from each location. After combining materials from the bags, samples from

each location were obtained for classification tests (Atterberg limits, sieve analysis and organic content),

Proctor density, and resilient modulus. The classification test results are reported in Table 1. Information

provided with the samples from GCME, Inc. indicated all material was collected from depth of 1 to 3 feet.

Table 1. Summary of Initial Classification Results

Sample

ID

Station

No.

Passing

No. 4,

%

Passing

No. 10,

%

Passing

No. 40,

%

Passing

No. 60,

%

Passing

No.

100, %

Passing

No.

200, %

Class.

Organic

Content,

%

LL/PI

LBR-1 125+50 79.4 76.3 71.2 58.6 29.1 5.9 A-3 1.5 N.P.

LBR-2 151+00 97.1 93.0 86.3 64.7 19.7 3.1 A-3 1.1 N.P.

LBR-3 174+20 99.7 99.2 92.9 71.8 22.7 2.2 A-3 1.1 N.P.

LBR-4 194+90 100.0 99.0 91.9 65.8 19.1 2.3 A-3 1.8 N.P.

LBR-5 221+80 92.1 89.1 84.0 68.7 32.1 6.2 A-3 0.7 N.P.

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In addition to the classification testing, the following test program was conducted:

(1) Standard Proctor, AASHTO T 99 (2) Resilient Modulus (MR), AASHTO T 307.

A summary of laboratory test results is included in Table 2. The resilient modulus values listed in this table

were obtained using the relationship developed from each individual test (resilient modulus versus bulk stress -

with bulk stress, Θ, defined as Θ = σ1 + σ2 + σ3), and using a bulk stress of 11 psi, which is the recommendation

from Dr. Ping’s research work in modeling the embankment in-situ stresses for Florida pavement conditions.

Two results are listed for each location because two samples were prepared for each location and they represent

the individual test result from each sample tested. The resilient modulus samples were compacted to within 1

pound per cubic foot (pcf) of the maximum density and 0.5 percent of the optimum moisture content as

determined by AASHTO T99.

Table 2. Summary of T-99 and MR Test Results

Sample ID

Passing

No. 200,

%

Standard

Proctor

Density, pcf

Optimum

Moisture

Content, %

Resilient Modulus

@ Θ=11psi

(psi)

LBR-1 6 109.8 10.3 14,949

14,293

LBR-2 3 104.7 12.5 14,092

12,779

LBR-3 2 102.1 13.6 11,311

11,945

LBR-4 2 102.8 14.6 11,605

11,718

LBR-5 6 108.7 12.2 13,398

13,876

To obtain a design embankment resilient modulus, a 90 percent method was used as outlined in both the

Flexible Pavement Design Manual and Soils and Foundations Handbook. The resilient modulus values were

ranked in ascending order and the percentage of values which were greater than or equal to the individual value

were determined. The results of this analysis are recorded in Table 3 and the corresponding graph of these

results is included as Figure 1. The numbers in parentheses (after the sample identification information)

represent the test number (either 1 or 2) for the corresponding resilient modulus value due to the fact that two

individual tests were performed on material from the same location (as shown in Table 2).

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Table 3. Ranked MR Test Results for 90 Percent Method

Rank Sample ID % ≥ MR (psi)

1 LBR-3 (1) 100 11,311

2 LBR-4 (1) 90 11,605

3 LBR-4 (2) 80 11,718

4 LBR-3 (2) 70 11,945

5 LBR-2 (2) 60 12,779

6 LBR-5 (1) 50 13,398

7 LBR-5 (2) 40 13,876

8 LBR-2 (1) 30 14,092

9 LBR-1 (2) 20 14,293

10 LBR-1 (1) 10 14,949

Figure 1. Ranked MR Test Results for 90 Percent Method

Based on the results shown in Table 3 and Figure 1, the resilient modulus corresponding to a 90th percentile is

11,600 psi, which would represent the design embankment MR value.