C. la-Security Foreces-FDA.pdf

LAUGHLIN AIR FORCE BASE, TEXAS

SECURITY FORCES COMPLEX

FOUNDATION AND PAVEMENT DESIGN ANALYSIS

PREPARED BY

U.S. ARMY CORPS OF ENGINEERS

FORT WORTH DISTRICT

ENGINEERING AND CONSTRUCTION DIVISION

DESIGN BRANCH

GEOTECHNICAL SECTION

CESWF-EC-DG

JUNE 2002

FOUNDATION AND PAVEMENT DESIGN ANALYSIS

1. General. The purpose of this report is to provide subsurface information, and foundation and pavement design recommendations for a Security Forces Complex at Laughlin Air Force

Base, Texas. The new complex will consist of three separate buildings on three separate sites.

The buildings are a 1,245 GSM Security Forces Operations Facility, a 229 GSM Combat Arms

Training and Maintenance Facility (CATM), and a 77 GSM Entry Access Control Point

(EACP). New building construction for the single-story Security Forces Center will be a structural steel braced frame system with a combination of brick veneer, EIFS (exterior insulation and finish system), translucent panels, and standing seam metal roofing. The CATM will be a single-story pre-engineered metal building system. The small EACP will consist of load-bearing masonry (CMU) walls with steel columns supporting a structural steel roof system. Support features include new parking areas, service drives, utilities, landscaping, and site improvements.

The project sites are spread across Laughlin AFB, with two of the facilities located within the built-up portion of the cantonment and third located on the far eastern end of the reservation. The Security Forces Center will be constructed adjacent to existing Building 140, which is located at the west corner of the intersection of Fourth Street and Colorado Avenue.

The EACP will be located southwest of the Main Gate House (Building 1) on the northern end of Liberty Drive. The CATM facility will be sited adjacent to Building 1100, which is located at the southern end of Fourth Street “extension” near the perimeter fence. Topographically, the sites are relatively flat with existing grades as listed below:

Building Existing Grades, m (NGVD)

Security Forces 335.50 – 338.25

EACP 322.75 – 323.75

CATM 322.50 – 322.75

2. Subsurface Investigation. A total of eleven (11) test holes were drilled at the project sites during April and May 2002 by the U.S. Army Corps of Engineers, Fort Worth District.

Borings 8A4C-424 through 10A-427 (4) were drilled at the Security Forces Center, borings

10A-428 through 10A–431 (4) were drilled at the EACP site, and the remaining three borings

(8A4C-432 through 10A-434) were drilled at the CATM site. All of the borings were drilled to determine subsurface conditions and to obtain representative soil and rock samples for laboratory testing. The test holes were advanced and samples recovered using 6-, 8-, and 10-inch diameter short flight augers, a 3-inch diameter Shelby-tube sampler, a 4-inch diameter core barrel sampler, and a 7-7/8-inch diameter rockbit. Representative soil and rock samples recovered from selective borings were sealed in airtight containers and taken to the laboratory of TEAM Consultants, Incorporated (Arlington, Texas) for testing. The borings were advanced to depths ranging from 1.52 meters to 5.79 meters below existing grade at the time of drilling.

The field investigation was performed using a Failing 1500 truck-mounted drill rig and conventional drilling attachments. Logging of the test holes was done in English units;

however, results of the field investigation, as presented in this report, were converted to the metric equivalent. Logs of borings and boring locations are shown on Plates LB1 through LB6

(Appendix A).

a. Groundwater Readings. Groundwater conditions were monitored during drilling operations and immediately upon completion of the test holes. All of the borings were dry at those times, except boring 8A4C-429, which was making water at a depth of 3.66 meters when the test hole was completed. It should be noted, however, that the presence of groundwater is most likely due to recent rainfall in the area, which resulted in a “perched” water table within a very permeable gravel deposit. Historically, the presence of groundwater in the Laughlin AFB area has been found to be seasonal and relative to the time of drilling, annual precipitation, and drainage conditions at the site.

b. Dynamic Cone Penetrometer Testing. Dynamic Cone Penetrometer testing (DCP) was performed in borings 10A-427, 10A-428, and 10A-433 for pavement design considerations. DCP test results are discussed in paragraphs 4 and 5, and presented in

Appendix D at the end of this report.

c. Soil Resistivity Testing. A soil resistivity test was performed at the approximate location of boring 3ST-425. The resistivity value measured in the field is 47,401 ohms-cm.

Soil resistivity test results are provided in the 'Remarks' column of the aforementioned log of boring (Appendix A).

3. Subsurface Conditions.

a. General Geology. The city of Del Rio, Texas lies within the boundaries of the

Edwards Plateau physiographic province, a Texas subdivision of the Great Plains physiographic province. This area is of moderate relief in which a sparse growth of vegetation is supported by the region's characteristic caliche-type soils. Del Rio is underlain by limestone of the Georgetown formation, which is the basal member of the Washita group, Cretaceous in age. Lithologically, the Georgetown formation consists of soft to moderately hard, argillaceous limestone with scattered, thin beds of marly or shaly material. Considerable jointing has been observed in outcrops within the area, with the most prominent striking in the northwest-southeast direction. Overburden in the area consists of alluvial sandy clay and limestone gravel varying in thickness from 30 centimeters to 2.1 meters. Within these deposits are localized zones, which are very hard due to secondary cementation.

b. Site Conditions.

(1) Security Forces Center. Presently, several existing buildings of various sizes, asphalt pavements, sidewalks, fencing, and above and below ground utilities occupy the project site. Existing grades in this area vary from approximate elevations 335.50 meters to

338.25 meters (NGVD) in a north-south direction. Stratigraphically, the site is characterized by low to high plasticity clays (CL and CH), clayey sands (SC), and clayey sandy gravel above a weathered limestone primary material. Thickness of the overburden is variable ranging from a thin veneer around 150 millimeters near the northern end of the site to approximately 1.4 meters within the central and southern confines. The residual soils are comprised of predominantly fine to coarse gravel fragments derived from the underlying parent material.

Liquid limits measured from representative samples of these materials range from 26 to 55 percent, plastic limits vary from 18 to 24 percent (8≤PI≤31), and in situ moisture contents vary between 11 and 25 percent.

A formation of limestone primary lies beneath the overburden and extends to the total depth investigated, 3.96 meters. The limestone is weathered stained white with strong brown, massive, hard to very hard (Rock Classification), moderate to well cemented, slightly fossiliferous, and contains chalky zones.

(2) Entry Access Control Point. The EACP site is void of any major obstacles to construction, except for some large mature trees, an existing earthen berm, and underground utilities. Topographically, the site slopes in the northwest direction, with existing grades varying from approximate elevations 323.75 meters to 322.75 meters (NGVD). Subsurface conditions consist of medium to high plasticity clays (CL and CH) that are interbedded with deposits of sandy gravels and clayey sands. These soils are present to the total depth investigated, 5.79 meters. The irregular bedding and discontinuities associated with these soils suggest that they may be fill materials. Representative samples of the clayey soils were subjected to Atterberg limits testing, and the results indicate that liquid limits vary from 45 to

68 percent and plastic limits vary from 17 to 20 percent (25≤PI≤46). In situ moisture contents vary between 9 and 19 percent.

(3) Combat Arms Training and Maintenance Facility. The CATM site is also void of any major obstacles to construction and is considered “unimproved” property. Existing grades within the proposed building footprint vary from approximate elevations 322.50 meters to 322.75 meters (NGVD). Subsurface conditions consist of an upper layer of medium plasticity clays and a deeper limestone primary material that is apparent to the total depth investigated, 3.96 meters. The lean clays are brown and white, very silty, gravelly, and limy.

Thickness of the overburden varies from approximately 1.2 meters at the building site to around 3.0 meters under the asphalt pavement and near the “existing road”. Results of

Atterberg limits testing indicate that the clayey soils have liquid limits ranging from 37 to 40 percent and plastic limits of 18 percent (19≤PI≤22). In situ moisture contents were found to vary from approximately 9 to 17 percent.

In this area of the installation, the limestone primary is initially highly weathered to a gravel/cobble consistency, but becomes massive and jointed at depths in excess of 1.8 meters.

The limestone is weathered stained strong brown and white, hard to very hard (Rock

Classification), well cemented, and contains limy clay seams and vuggy zones.

Subsurface conditions representative of the individual building sites are shown on the boring logs, Sheets LB4 through LB6. The legend on the boring logs show overburden materials as classified in the laboratory using procedures presented in ASTM D 2488. It should be noted that the actual interface between material types might be far more gradual or abrupt than presented; therefore, actual subsurface conditions in areas not sampled may differ from those predicted. The nature and extent of variations across the sites may not become evident until construction commences, and the actual construction process may alter subsurface conditions as well. If variations become evident at the time of construction, CESWF-EC-DG should be contacted to determine if the recommendations presented in this report need to be reevaluated.

4. Testing.

a. Laboratory Testing. Representative soil and rock samples were subjected to laboratory testing for identification, moisture content, grain-size distribution, Atterberg limits, density, and strength. The accumulative test results are tabulated and presented in English units in Appendix C. Results of identification and moisture content testing are shown on the individual boring logs, Plates LB4 through LB6 (Appendix A). Visual descriptions and

Unified Soil Classifications are based on procedures presented in ASTM D 2488.

The laboratory test results are also presented graphically for each building site in

Appendix B as follows: Plasticity characteristics are shown on Plates 1, 1A and 1B, Plasticity

Charts. Moisture content values are shown with respect to depth on Plates 2, 2A and 2B.

Atterberg limits test results are shown with respect to depth on Plates 3, 3A and 3B. Dry density values of representative undisturbed samples collected at the Security Forces Center site and their corresponding moisture contents are shown with respect to depth on Plate 4.

Shear strength characteristics of the limestone primary encountered at the site of the

Security Forces Center were analyzed in the laboratory using unconfined compression testing.

One sampled collected from boring 8A4C-424 and another collected from boring 8A4C-426 were selected for analysis. Shear strength test results are presented below and in English units in Appendix C.

Boring Depth, m δ, kg/m3 Qu, MPa

8A4C-424 2.77 2500 82.7 8A4C-426 3.79 2377 7.40

b. Field Testing. Dynamic Cone Penetrometer (DCP) testing was performed in borings

10A-427, 10A-428, and 10A-433 to evaluate the subgrade for pavement design considerations.

A DCP consists of a steel rod with a steel cone attached to one end and a sliding single-mass hammer. For this project, the DCP test was performed by driving the steel cone into the soil using a 10.1-pound sliding hammer dropped from a height of 22.6 inches (575 millimeters).

The number of blows required for each 0.4 inch (10-mm) or higher of penetration was recorded as the "penetration per blow set"; therefore, the more penetration achieved per blow indicates that a "weaker" soil layer was encountered. Typically, penetration measurements are taken to a depth of 39.4 inches (1000 millimeters) or when refusal is achieved. Refusal is defined as the point when the cone cannot penetrate the soil more than 0.4 inches (10 millimeters). DCP test results are summarized in the table below and are presented in Appendix D at the end of this report.

Depth, mm CBR, % k, kPa/mm

0 – 150 8-52 46.4-86.0 >150 5-19 36.4–77.1

5. Discussions. The following discussions are provided in support of the foundation and pavement design recommendations made for the Security Forces Complex.

a. Soil Activity Considerations. Subsurface conditions at the project sites are very similar in that there is a surface veneer of low to high plasticity clays above a limestone primary. Thickness of the overburden varies from approximately 150 millimeters to 1.4 meters. The only exception is at the EACP site, where the overburden is present to the total depth investigated, 5.79 meters. The in situ soils at the EACP site are predominantly lean clays that are interbedded with sand and gravel lenses. Based on moisture content and

Atterberg limits test results, the overburden materials at all three sites are moisture deficient to a depth of approximately 1 meter below existing grade. Therefore, removing and replacing these soils with compacted nonexpansive backfill material will greatly reduce the shrink-swell potential to tolerable levels (<25mm).

b. Foundation Design Considerations. Based on subsurface conditions encountered at each building site, there are two foundation systems considered applicable for this project;

namely, dug and formed spot spread and/or continuous spread footings and a “stiffened” mat slab. At the Security Forces Center and CATM sites, the proximity of a competent limestone material to ground surface suggests the use of the shallow footing system. Historically, footing foundations have performed satisfactorily with respect to limiting long-term foundation movements in the form of settlement. For the shallow foundations to perform satisfactorily, footings should be “socketed” at least 150 millimeters into the limestone primary to ensure proper load transfer to the founding material. Top of rock was encountered at depths ranging from 150 millimeters to 1.2 meters below existing grade. Laboratory shear strength test results indicate that an allowable bearing capacity of 240 kPa (net) can be used to size the footings while maintaining a factor of safety greater than 3 against shear failures. Designing the foundations for the aforementioned bearing allowable will ensure that post construction movements will be negligible. As an option, the structural designer can found footings within compacted nonexpansive fill in an attempt to reduce the construction costs associated with placing footings at deeper depths (>1 meter). For this option, an allowable bearing capacity of

96 kPa (net) should not be exceeded when sizing the footings.

The relatively small Entry Control Point building (77 GSM) should be supported on a reinforced concrete “stiffened” mat slab. A mat slab is considered the most feasible based on the soil conditions encountered at the site, the structural system proposed, and the fact that the building will impose relatively light loads on the foundation. The mat slab should consist of both interior and exterior beams constructed to interact monolithically with the floor slab. The beams should extend at least 610 millimeters below outside finished grade. As mentioned above, the upper 1 meter of in situ materials are the most active, and below this depth, the situ materials become more stable. To this end, removing the active subgrade and replacing with nonexpansive backfill will essentially reduce the expansion potential to negligible levels.

Under moderate loading, long-term settlements will be within acceptable limits as well.

However, to ensure adequate stiffness is provided, it is recommended that interior beams be spaced no further than 4.5 meters center-to-center. A safe bearing pressure of 96 kPa (net) should not be exceeded when designing the mat slab foundation.

c. Floor Slab Systems and Subgrade Preparation Requirements. Ground-level floor slabs within the Security Forces Center and Combat Arms Training and Maintenance facility can be placed on-grade. Floor slabs in deformation sensitive areas that cannot tolerate up to 13 millimeters of differential movement should be supported above a minimum 150-millimeter void. Soil-supported floor slabs should be isolated from the foundation or building structure using felt isolation joints. Transitional areas, such as door openings, can be dowelled to prevent offsets from occurring.

Based on results of laboratory testing, the upper one meter of overburden materials are the considered to be the most active; therefore, these soils should be removed and replaced with compacted nonexpansive backfill material to reduce their shrink-swell potential. If the limestone primary is encountered prior to reaching the one meter depth, excavation operations can be stopped and the nonexpansive backfill can then be placed. Any additional fill required to achieve the final subgrade elevation below the floor slabs should be nonexpansive as well.

Nonexpansive soils should be placed in controlled lifts not exceeding 205 millimeters in loose thickness and compacted to not less than 92 percent of laboratory maximum density as determined in accordance with ASTM D 1557

d. Pavement Design Considerations. The pavement designs presented in this report are based on criteria contained in TM 5-822-5/AFM 88-7, Chapter 1, TM 5-822-2/AFM 88-7, Chapter 5, and engineering judgment.

(1) Traffic Types and Conditions. Five (5) pavement structures were analyzed and designed for this project; namely, asphalt parking areas, access drives, and service drives, and concrete aprons in front of trash dumpster pad(s) and the warehouse floor slab subjected to forklift traffic. Types of vehicles expected to occupy the pavements are light to medium-duty passenger cars and trucks, two- and three-axle trucks, 27-kN forklifts, and fire/emergency medical vehicles. Based on criteria contained in the aforementioned Technical Manuals, the following traffic conditions were assigned:

Pavement Structure Traffic Type Street Class Design Index

Parking Areas Category III Class E 3 Access Drives Category III Class E 3 Service Drives Category III Class E 3 Aprons (Trash) Category IVA Class F 4 Warehouse Floor Slab Category IVA Class E 5

(2) Pavement Design Parameters. California Bearing Ratio (CBR) and plate bearing tests were not performed for this project due to the availability of historical test results. The historical data indicates that the clayey subgrade indicative of Laughlin AFB can be assigned CBR values between 4 and 7 percent when compacted to 90 percent of laboratory maximum density (ASTM D 1557), and around 19 percent when lime-stabilized and compacted to 95 percent of maximum density. Previously performed plate bearing tests indicate that modulus of subgrade reaction (k) values of 27.1 kPa/mm to 33.9 kPa/mm can be expected for the clayey subgrade when compacted to 90 percent of laboratory maximum density. This value can be upgraded to 40.7 kPa/mm when the same soils are lime-stabilized and compacted to 95 percent of laboratory maximum density.

More recently, Dynamic Cone Penetrometer (DCP) testing is performed in the field to evaluate the in situ strengths of the raw subgrade for pavement design considerations. The

DCP test assigns a strength value to the subgrade, which in turn is used to derive at “in situ”

CBR and modulus of subgrade reaction values. As previously presented in this report, the in situ CBR values measured within the upper 300 millimeters of soils tested range from approximately 5 to 52 percent, and the in situ modulus of subgrade reaction values (k) range from 36.4 kPa/mm to 86.0 kPa/mm. The lower end strength parameters obtained from the field tests are comparable to the historical values typically used for in situ soils having moderate plasticity levels. The relatively high values recorded within the subgrade can be attributed to the amount of gravel present. For this project, many of the pavement structures will be built on clayey soils of low to medium plasticity; therefore, the load-carrying capabilities of these soils will be moderate. To this end, a CBR value of 7 percent and a modulus of subgrade reaction of 33.9 kPa/mm were assigned to the raw subgrade for pavement design consideration.

It should be noted that these values consider the raw subgrade being compacted to 90 percent of laboratory maximum density (ASTM D 1557).

(3) Lime Stabilization. The plasticity levels of the near surface in situ materials suggest that these soils will have a slight to moderate expansion potential when subjected to changing moisture conditions. However, lime stabilizing the active subgrade to reduce the plasticity level will not be considered for this project. Base course materials will be used as a substitute as a means to improve the strength characteristics of the pavement sections and to reduce the in-place cost of the pavement structures.

(4) Material Sources. Material sources in the Del Rio (and San Antonio) areas are capable of producing a good quality crushed aggregate for concrete mixes to meet strength requirements. Therefore, a concrete flexural strength of 4.14 MPa at 28 days was considered in the design of rigid pavements. To date, Alkali/Silica Reaction with Portland Cement

Concrete has never been a problem when using local aggregate sources.

6. Recommendations. The following foundation and pavement design recommendations are based on results of the field investigation, laboratory testing, and engineering studies.

a. Foundation Design Recommendations. The proposed Security Forces Center and

Combat Arms Training and Maintenance facility should be supported on dug and formed spot spread and/or continuous spread footings. The footings should be “socketed” at least 150 millimeters into the white and brown limestone primary indicative of each site. For cost estimation purposes, the following bearing elevations should be provided on the contract drawings a foundation note:

Building Bearing El, m (NGVD)

Security Forces Center 335.75

CATM 321.25

An allowable bearing capacity of 240 kPa (net) should not be exceeded when sizing the footings. The load used to size the footings should consist of full dead load plus that portion of the live load that acts more or less continuously, usually 50 percent. Load-carrying masonry walls should be supported on a minimum 457-millimeter wide continuous footing and founded as stated above. Non-load bearing masonry walls (partitions) can be placed on a minimum

305-millimeter wide "shovel beam" footing.

Alternatively, footings can be placed within the compacted nonexpansive fill material in an attempt to reduce the depth to bearing. An allowable bearing capacity of 96 kPa (net) should not be exceeded when sizing the footings. Again, the load used to size the footings should consist of full dead load plus that portion of the live load that acts more or less continuously, usually 50 percent.

(1) Entry Access and Control Point Building. The EACP building should be supported on a reinforced concrete “stiffened” mat slab. The mat slab should consist of a floor slab and a network of interior and exterior beams constructed to interact monolithically. The beams should bottom a minimum of 610 millimeters below outside finished grade. Interior beams should be placed at intervals not to exceed 4.5 meters and should intersect beneath columns. The beams should be sized for an allowable bearing capacity of 96 kPa (net). For this phase of design, it should be noted that (1) the structural load is supported solely on the beam and beam intersections, (2) load transfer occurs over the effective beam width, and (3) the beam and soil remain in contact. Beam intersections should be widened at column locations to accommodate the above allowable bearing value for the anticipated load condition.

The load used to size the beams should consist of full dead load plus that portion of the live load that acts more or less continuously, usually 50 percent. The “stiffened” mat slab will not have to be designed for expansive soil conditions if the subgrade preparation requirements presented in this report are adhered to.

(2) Ground-Level Floor Slabs. Ground-level floor slabs within the Security

Forces Center and CATM facility can be placed on-grade. Deformation sensitive areas that cannot tolerate up to 13 millimeters of long-term differential floor slab movement should be supported above a minimum 150-millimeter void. Ground-supported floor slabs should be isolated from any portion of the foundation or building structure using a minimum 1.46 kg/m2 felt isolation joint. In doing so, the building structure-floor slab interface should be designed to accept vertical movements so that the operation of the facilities will not be affected. This will result in the best performance. Alternatively, transitional areas, such as door openings, can be doweled to prevent offsets from occurring. In these areas, the slab should bear on the grade beam to create a single joint at one face of the grade beam. Slab edges should extend to the outside face of the grade beam at exterior door locations. A polyethylene vapor barrier and a minimum 150-millimeter capillary water barrier should be provided beneath all floor slabs

(including the mat slab foundation) supported on-grade.

(3) Subgrade Preparation and Fill Requirements. Subgrade preparation should consist of removing at least 1 meter of existing soils or all soils to the top of the limestone primary, whichever occurs first, and replacing with compacted nonexpansive backfill. Any additional fill required to raise the subgrade to the final elevation below the floor slab system should be nonexpansive as well. The upper 150 millimeters of subgrade exposed after excavation operations should be scarified and recompacted to the same density as required for nonexpansive fill. Nonexpansive fill should be placed in controlled lifts not exceeding 205 millimeters in loose thickness and compacted to not less than 92 percent maximum density as determined in accordance with ASTM D 1557.

(4) Material Testing Requirements. Testing shall be the responsibility of the contractor to ensure that the subgrade, fill, and backfill materials are properly compacted. To this end, the following frequencies of testing shall be included in the contract as a minimum:

• In-place density of the subgrade, fills, and backfills shall be performed for every 250 square meters per lift in accordance with ASTM D 1556 or ASTM D 2922.

• Optimum Moisture and Laboratory Maximum Density of nonexpansive fill and backfill shall be performed for every 385 cubic meters or when any change in material occurs.

(5) Below-Grade Structures. The following information is provided for the design of all below-grade structures (if applicable). All structures shall be designed using an at-rest lateral earth pressure coefficient of (ko) 0.7, an angle of internal friction (φ) equal to

28o, an allowable bearing capacity of 96 kPa, and a cohesion value (c) of 4.8 kPa. The backfill material should be assumed to have a moist unit weight of 2000 kg/m3 and all backfill should be nonexpansive material.

(6) Drainage and Landscaping. Proper drainage is an important design consideration to ensure satisfactory long-term foundation performance. Exterior grading adjacent to the buildings should be sloped away from the structures a minimum of 5 percent for the first 3 meters. Runoff from the roofs should be adequately discharged away from foundation edges. In no case should water be allowed to pond adjacent to or beneath the buildings, both during and after construction.

Landscaping adjacent to the buildings should be kept to a minimum. Large trees and bushes should not be planted any closer to the foundations than its mature "umbrella" width.

Maintaining a growth of grass around the facilities is recommended. Installing an irrigation system adjacent to the foundations is advisable, but this system and the drainage conditions around the building must be maintained over the life of the structure.

(7) Foundation Material Definitions.

(a) Satisfactory Materials. Satisfactory Materials include materials classified in ASTM D 2487 as GW, GM, GC, GP, SW, SM, SP, SC, CL, and CH and shall be free of trash, debris, roots, or other organic matter, or stones larger than 76 millimeters in any dimension.

(b) Unsatisfactory Materials. Unsatisfactory Materials include materials classified in ASTM D 2487 as Pt, OH, OL, ML, MH and any other materials not defined as satisfactory.

(c) Nonexpansive Soils. Nonexpansive Soils shall meet the requirements of Texas Department of Transportation Standard Specification for base course, Item 247, Type A, Grade 1 or 2.

(d) Cohesionless and Cohesive Materials. Cohesionless Materials include materials classified in ASTM D 2487 as GW, GP, SW, and SP. Cohesive Materials include materials classified as GC, SC, ML, CL, MH, and CH. Materials classified as GM and

SM will be identified as cohesionless only when the fines are nonplastic.

(e) Capillary Water Barrier. Capillary Water Barrier shall consist of clean, crushed, nonporous rock, crushed gravel, or uncrushed gravel. The maximum particle size shall be 38 millimeters and no more than 2 percent by weight shall pass the 4.75-millimeter (No. 4) size sieve.

The above material definitions, subgrade preparation procedures, and material testing requirements should be presented in guide specification CEGS-02315 EXCAVATION, FILLING AND BACKFILLING FOR BUILDINGS.

b. Pavement Design Recommendations. The pavement designs presented in this report are based on criteria contained in TM 5-822-5/AFM 88-7, Chapter 1, TM 5-822-2/AFM 88-7, Chapter 5, and engineering judgment.

(1) Rigid Pavements. The following rigid pavement sections are recommended for an apron in front trash dumpster pad(s) and the building floor slab within the warehouse.

For the rigid pavement designs, a modulus of subgrade reaction equal to 33.9 kPa/mm and a concrete flexural strength of 4.14 Mpa at 28 days were considered, unless noted otherwise.

(a) Apron in front of Trash Dumpster Pad(s). The following pavement section is recommended for a minimum distance of 4.57 meters in front of trash dumpster pads.

The design is based on Category IVA Traffic and a Class F Street (DI=4).

150mm Portland Cement Concrete reinforced with No. 13 bars (metric) spaced 406 millimeters o.c.e.w.

150mm Aggregate Base Course compacted to at least 95 percent of laboratory maximum density (ASTM D 1557)

150mm Raw Subgrade compacted to at least 90 percent of laboratory maximum density (ASTM D 1557)

Reinforcement for odd-shaped slabs, joint design, joint spacing, and other details should be in accordance with the latest edition of the SWD-AEIM and TM 5-822-5, where applicable. The reinforcement bars should be placed a minimum of 38 millimeters clear distance from the surface of the pavement.

(b) Warehouse Floor Slab. The following pavement section is based on

Category IVA Traffic, Class E Street (DI=5), an effective modulus of subgrade reaction equal to 54.3 kPa/mm (upgraded due to nonexpansive fill), and a concrete flexural strength of 4.14

MPa at 28 days. The vehicular floor slab should have a minimum thickness of 150 millimeters and reinforced with No. 13 bars (metric) spaced 305 millimeters on-center and in each direction. Subgrade preparation below the floor slab should be in accordance with the

Foundation Design Recommendations presented in this report.

Design of the vehicular floor slab supported on-grade is based upon vehicle-imposed loads only, without regard for stresses caused by stationary live loads and/or other loading conditions.

(2) Flexible Pavement. The following pavement section is recommended for the parking areas, access drives, and service drives. The design is based on Category III

Traffic, Class E Street (DI=3), and a CBR value of 7 percent for the raw subgrade when compacted to 90 percent of laboratory maximum density.

38mm Hot-Mix Surface Course

150mm Aggregate Base Course compacted to at least 100 percent of laboratory maximum density (ASTM D 1557)

150mm Subbase Course compacted to at least 95 percent of laboratory maximum density (ASTM D 1557)

150mm Raw Subgrade compacted to at least 90 percent of laboratory maximum density (ASTM D 1557)

The following notes should be incorporated as part of the pavement details shown on the contract drawings.

1. “The moisture content shall be at least 1 percent above optimum during compaction of the raw subgrade.”

2. “The layer of subbase course can be substituted with aggregate base course using the same thickness and compaction requirements.”

(3) Pavement Material Definitions.

(a) Hot-Mix Surface Course. Aggregates and asphaltic materials shall conform to the requirements of the Texas Department of Transportation, Standard

Specifications for Construction of Highways, Streets and Bridges, (TXDOT, Std Spec), Items

300 and 340. The paving mixture shall conform to the requirements for Type "D" (fine-graded surface course) grading. Asphaltic material for the paving mixture should be asphaltic cement, viscosity grade AC-20 or performance grade PG64-22. Guide Specification CEGS-02741

BITUMINOUS PAVING FOR ROADS, STREETS AND OPEN STORAGE AREAS should be edited to present the above requirements.

(b) Prime Coat and Tack Coat. Asphaltic material for the prime coat shall be cut-back asphalt, grade MC-30, conforming to the requirements of TXDOT, Std Spec, Item 300, "Asphalts, Oils, Emulsions." Prime coat should be applied to the surface of the aggregate base course. Asphaltic material for the tack coat shall be cut-back asphalt, grade

RC-250, or emulsified asphalt, grade SS-1, conforming to the requirements of TXDOT, Std

Spec, Item 300, "Asphalts, Oils, Emulsions." Tack coat should be applied to all surfaces that contact new asphalt pavement. Guide Specification CEGS-02748 BITUMINOUS TACK AND

PRIME COATS should be edited to present the above requirements.

(c) Aggregate Base Course. Aggregates shall conform to the requirements of Guide Specification CEGS-02722 AGGREGATE BASE COURSE. The gradation should conform to the requirements of TXDOT, Std Spec, Item 247, for Type "A", Grade 1 material.

(d) Subbase Course. Material shall conform to Guide Specification

02721 SUBBASE COURSE and have a CRB value of 20 percent.

(e) Raw Subgrade. The material shall conform to the requirements of

Guide Specification CEGS-02300 RAW SUBGRADE.

(f) Portland Cement Concrete. The material shall conform to the requirements of Guide Specification 03300 CAST-IN-PLACE STRUCTURAL CONCRETE.

For vehicular pavements, the maximum nominal size aggregate should be 38 millimeters and the concrete mixture should be designed to attain a flexural strength of 4.14 MPa at 28 days.

(4) Pavement Material Testing Requirements. Testing shall be the responsibility of the contractor to ensure that the subgrade, subbase course, aggregate base course, and hot-mix surface course are properly constructed. To this end, the following testing requirements shall be included in the appropriate contract specifications as a minimum:

• In-place density testing of the subgrade, subbase course, and aggregate base course shall be performed, at a minimum, every 500 square meters per lift in accordance with ASTM D 1556 and ASTM D 2922. ASTM D 1556 shall be used as a check at least once per lift for each 2500 square meters of completed subgrade and aggregate base course.

• Before starting work, at least one sample of subbase course and aggregate base course material shall be tested in accordance with ASTM C 136. After the initial test, a minimum of one sieve analysis (ASTM C 136 and ASTM D 422) shall be performed for each 1000 metric tons of subbase and aggregate base course placed, with a minimum of one analysis performed for each day’s run until the course is completed. One liquid limit and plasticity index shall be performed for each sieve analysis per ASTM D 4318

• Wear tests shall be performed in accordance with ASTM C 131. A minimum of one test per aggregate base course material source shall be run.

• Thickness of the subbase course and aggregate base course shall be measured for each 500 square meters of material placed. Compacted thickness of the course shall be as presented in this report and the completed section shall be within 9 millimeters of the thickness presented.

• Hot Bin gradations for the asphalt wearing course shall be tested in accordance with ASTM C 136 and ASTM C 117. A minimum of one test shall be conducted. Marshall specimens shall be taken in accordance with methods described in AI MS-2. At least two sets of specimens shall be taken. Asphalt extractions shall be performed in accordance with ASTM D 2172, Method A or B. At least one asphalt extraction shall be conducted. Field density tests shall be conducted in accordance with ASTM D 2950. One test shall be conducted for each 250 square meters of pavement placed. The mat density shall be 97.5 to 100.5 percent and the joint density shall be 95.5 to 100.5 percent of the density obtained from laboratory-compacted specimens. Thickness measurements shall be taken at a minimum of one measurement for each 836 square meters of pavement placed.

• The Job Mix Formula for the bituminous mixture shall be furnished to the

Contracting Officer for approval. The formula will indicate the percentage of each stockpile and mineral filler, the percentage of each size aggregate, the percentage of bitumen, and the temperature of the completed mixture when discharged from the mixer. The Contractor shall file with the Contracting Officer certified delivery tickets for all aggregates and bituminous materials actually used in construction. The finished mixture shall be designed using procedures contained in AI MS-2 and the criteria shown below. All samples will be compacted with 50 blows of specified hammer on each side of the sample.

Stability (minimum) – 2200 Newtons Flow (maximum), 0.25mm – 20 Air Voids, percent – 3% to 5% Percent Voids in mineral aggregate – 14

TSR, minimum percent - 75

• Smoothness measurements shall be taken in successive positions parallel to the pavement centerline with a 3.66-meter straightedge. Measurements shall be taken perpendicular to the pavement centerline at 4.5-meter intervals. Surface smoothness shall not exceed 9.5 millimeters.

References:

• TEAM Consultants, Incorporated Report No. 0270295C

• TM 5-818-1/AFM 88-3, Chapter 7 – Soils and Geology Procedures for Foundation Design of Building and Other Structures

• TM 5-818-7 – Foundations in Expansive Soils

• TM 5-822-5/AFM 88-7, Chapter 1 – Pavement Design for Roads, Streets, Walks, and Open

Storage Areas

• TM 5-822-2/AFM 88-7, Chapter 5 – General Provisions and Geometric Design For Roads, Streets, Walks, and Open Storage Areas

• TM 5-809-12/AFM 88-3, Chapter 15 – Concrete Floor Slabs On Grade Subjected to Heavy

Loads

• Texas Department of Transportation - Standard Specifications For Construction of

Highways, Streets and Bridges

• SWD-AEIM Architectural-Engineering Manual

• CEGS Guide Specifications For Construction

FORT WORTH DISTRICT

JUNE 2002

APPENDIX A

BLACK_M

See full size sheets for boring logs and locations.

APPENDIX B

SECURITY FORCES CENTER

PLASTICITY CHART

A-LINE

U-LINE

CL-ML

0 10 20 30 40 50 60 70 80 90 100 110 120

LIQUID LIMIT

PL

A

ST

IC

IT

Y

IN

D

E X

PLATE 1

ENTRY ACCESS CONTROL POINT

A-LINE

U-LINE

CL-ML

0 10 20 30 40 50 60 70 80 90 100 110 120

LIQUID LIMIT

PL

A

ST

IC

IT

Y

IN

D

E

PLATE 1A

COMBAT ARMS TRAINING AND MAINTENANCE

A-LINE

U-LINE

CL-ML

0 10 20 30 40 50 60 70 80 90 100 110 120

LIQUID LIMIT

PL

A

ST

IC

IT

Y

IN

D

E

PLATE 1B

MOISTURE CONTENT VS DEPTH

-4.00

-3.50

-3.00

-2.50

-2.00

-1.50

-1.00

-0.50

0.00

0 2 4 6 8 10 12 14 16 18 20 22 24 26

MOISTURE - %

D E

PT

H

M

E T

E R

S

PLATE 2

-3.00

-2.50

-2.00

-1.50

-1.00

-0.50

0.00

0 2 4 6 8 10 12 14 16 18 20

MOISTURE - %

D E

PT

H

M

E T

E R

PLATE 2A

-2.50

-2.00

-1.50

-1.00

-0.50

0.00

0 2 4 6 8 10 12 14 16 18

MOISTURE - %

D E

PT

H

M

E T

E R

PLATE 2B

ATTERBERG LIMITS VS DEPTH

-1.00

-0.75

-0.50

-0.25

0.00

0 5 10 15 20 25 30 35 40 45 50 55 60

MOISTURE - %

D E

PT

H

M

E T

E R

S

MC LL PL

PLATE 3

-3.00

-2.50

-2.00

-1.50

-1.00

-0.50

0.00

0 10 20 30 40 50 60 70

MOISTURE - %

D E

PT

H

M

E T

E R

MC LL PL PLATE 3A

-2.50

-2.00

-1.50

-1.00

-0.50

0.00

0 5 10 15 20 25 30 35 40

MOISTURE - %

D E

PT

H

M

E T

E R

MC LL PL PLATE 3B

MOISTURE CONTENT - DRY DENSITY VS DEPTH

-4.00

-3.50

-3.00

-2.50

-2.00

-1.50

-1.00

-0.50

0.00

0 25 50 75 100 125 150 175 200 225 250 275

MOISTURE - % DRY DENSITY - kg/cu. m x 10-1

D E

PT

H

M

E T

E R

MC DD PLATE 4

APPENDIX C

Sample Boring Depth

No. (ft.) #4 #10 #20 #40 #60 #80 #100 #200

8A4C-424 C - 1 8.7 - 9.5 Tan Limestone N/A ----- ----- ----- ----- ----- ----- ----- -----

3ST-425 JAR A 0.0 - 4.5 Light Gray Clayey Sand wlimestone fragments SC 78.3 63.7 54.2 48.5 44.6 42.1 41.1 37.3

ST - 1 0.0 - 2.0 NO TESTS N/A ----- ----- ----- ----- ----- ----- ----- -----

ST - 2 3.0 - 5.0 NO TESTS N/A ----- ----- ----- ----- ----- ----- ----- -----

8A4C-426 JAR A 0.0 - 1.1 Brown Clay CH 95.7 91.9 89.4 87.9 86.7 85.5 84.9 82.1 JAR B 1.1 - 4.0 Tan Sandy Clay w/occ. limestone frag. CL 88.7 83.5 79.2 76.1 73.6 71.5 70..4 66.2

C - 1 12.1 - 12.8 Tan Limestone N/A ----- ----- ----- ----- ----- ----- ----- -----

10A-427 JAR A 0.2 - 0.6 Tan Clayey Sand w/limestone fragments SC 81.3 73.5 66.1 59.9 55.5 52.2 50.8 45.6 JAR B 0.6 - 4.2 Gray & Brown Clayey Sand w/limestone fragments SC 79.4 67.4 59.2 54.7 51.6 49.7 48.9 44.7

10A-428 JAR A 0.7 - 4.0 Grayish Brown Sandy Clay w/occ. limestone frag. CL 83.6 80.1 77.8 76.3 74.5 73.2 72.6 68.4 JAR B 4.0 - 7.4 Tan Sandy Clay w/occ. limestone frag. CL ----- ----- ----- ----- ----- ----- ----- ----- JAR C 7.4 - 10.0 Tan Clay CH ----- ----- ----- ----- ----- ----- ----- -----

10A-432 JAR A 0.0 - 4.0 Grayish Brown Sandy Clay w/silt CL 97.4 94.9 93.2 92.1 91.2 90.3 89.9 86.8

C - 1 10.0 - 10.5 NO TESTS N/A ----- ----- ----- ----- ----- ----- ----- -----

10A-434 JAR A 0.0 - 3.7 Tan Sandy Clay w/silt CL 96.8 95.3 94.0 93.1 92.3 91.6 91.3 89.0 JAR B 3.7 - 8.8 Tan & Brown Sandy Clay CL 93.0 88.0 84.5 82.1 80.1 78.1 77.1 71.4

Sample No.

Percent Passing SieveVisual Description & Unified Soil Classification (ASTM D-2488)

SUMMARY OF LABORATORY TEST RESULTS

LABORATORY TESTING SERVICES

SECURITY FORCES COMPLEX

LAUGHLIN AFB, TEXAS

Sample Moisture Unit Dry Boring Depth Content Weight

No. (ft.) (%) (pcf) LL PL PI Remarks

8A4C-424 C - 1 8.7 - 9.5 Tan Limestone N/A 0.6 156.1 ----- ----- ----- -----

3ST-425 JAR A 0.0 - 4.5 Light Gray Clayey Sand wlimestone fragments SC 11.5 ----- 36 22 14 -----

ST - 1 0.0 - 2.0 NO TESTS N/A ----- ----- ----- ----- ----- -----

ST - 2 3.0 - 5.0 NO TESTS N/A ----- ----- ----- ----- ----- -----

8A4C-426 JAR A 0.0 - 1.1 Brown Clay CH 21.7 ----- 55 24 31 ----- JAR B 1.1 - 4.0 Tan Sandy Clay w/occ. limestone frag. CL 25.0 ----- 32 22 10 -----

C - 1 12.1 - 12.8 Tan Limestone N/A 3.6 148.4 ----- ----- ----- -----

10A-427 JAR A 0.2 - 0.6 Tan Clayey Sand w/limestone fragments SC 12.0 ----- 26 18 8 ----- JAR B 0.6 - 4.2 Gray & Brown Clayey Sand w/limestone fragments SC 16.4 ----- 37 21 16 -----

10A-428 JAR A 0.7 - 4.0 Grayish Brown Sandy Clay w/occ. limestone frag. CL 18.2 ----- 45 20 25 ----- JAR B 4.0 - 7.4 Tan Sandy Clay w/occ. limestone frag. CL 19.3 ----- 48 17 31 ----- JAR C 7.4 - 10.0 Tan Clay CH 9.0 ----- 65 19 46 -----

10A-432 JAR A 0.0 - 4.0 Grayish Brown Sandy Clay w/silt CL 9.0 ----- 38 18 20 -----

C - 1 10.0 - 10.5 NO TESTS N/A ----- ----- ----- ----- ----- -----

10A-434 JAR A 0.0 - 3.7 Tan Sandy Clay w/silt CL 11.1 ----- 37 18 19 ----- JAR B 3.7 - 8.8 Tan & Brown Sandy Clay CL 17.2 ----- 40 18 22 -----

SUMMARY OF LABORATORY TEST RESULTS

LABORATORY TESTING SERVICES

SECURITY FORCES COMPLEX

LAUGHLIN AFB, TEXAS

No. Unified Soil Classification (ASTM D-2488) Atterberg LimitsSample Visual Description &

Sample Moisture Unit Dry Confining Strain @ Boring Depth Content Weight Pressure Qu Failure Type

No. (ft.) (%) (pcf) (tsf) (tsf) (%) Failure

8A4C-424 C - 1 8.7 - 9.5 Tan Limestone N/A 0.6 156.1 0.0 864 N/A * VERTICAL

3ST-425 JAR A 0.0 - 4.5 Light Gray Clayey Sand wlimestone fragments SC 11.5 ----- ----- ----- ----- -----

ST - 1 0.0 - 2.0 NO TESTS N/A ----- ----- ----- ----- ----- -----

ST - 2 3.0 - 5.0 NO TESTS N/A ----- ----- ----- ----- ----- -----

8A4C-426 JAR A 0.0 - 1.1 Brown Clay CH 21.7 ----- ----- ----- ----- ----- JAR B 1.1 - 4.0 Tan Sandy Clay w/occ. limestone frag. CL 25.0 ----- ----- ----- ----- -----

C - 1 12.1 - 12.8 Tan Limestone N/A 3.6 148.4 0.0 77.3 N/A * VERTICAL

10A-427 JAR A 0.2 - 0.6 Tan Clayey Sand w/limestone fragments SC 12.0 ----- ----- ----- ----- ----- JAR B 0.6 - 4.2 Gray & Brown Clayey Sand w/limestone fragments SC 16.4 ----- ----- ----- ----- -----

10A-428 JAR A 0.7 - 4.0 Grayish Brown Sandy Clay w/occ. limestone frag. CL 18.2 ----- ----- ----- ----- ----- JAR B 4.0 - 7.4 Tan Sandy Clay w/occ. limestone frag. CL 19.3 ----- ----- ----- ----- ----- JAR C 7.4 - 10.0 Tan Clay CH 9.0 ----- ----- ----- ----- -----

10A-432 JAR A 0.0 - 4.0 Grayish Brown Sandy Clay w/silt CL 9.0 ----- ----- ----- ----- -----

C - 1 10.0 - 10.5 NO TESTS N/A ----- ----- ----- ----- ----- -----

10A-434 JAR A 0.0 - 3.7 Tan Sandy Clay w/silt CL 11.1 ----- ----- ----- ----- ----- JAR B 3.7 - 8.8 Tan & Brown Sandy Clay CL 17.2 ----- ----- ----- ----- -----

* Strain measurements were not recorded for this test. This sample was an intact core of rock which was sawed square, ends capped with hydrostone high strength gypsum, and tested for compressive strength in accordance with ASTM D-2398 "Unconfined Compressive Strength of Intact Rock Core Specimens".

Visual Description & No. Unified Soil Classification (ASTM D-2488)

Sample

SUMMARY OF LABORATORY TEST RESULTS

LABORATORY TESTING SERVICES

SECURITY FORCES COMPLEX

LAUGHLIN AFB, TEXAS

APPENDIX D

0 0

127 5

254 10

381 15

508 20

635 25

762 30

889 35

SUBGRADE 2.00" CBR 52

(IN) (MM) TEST PROFILE

DCP TEST DATA

Project: SECURITY FORCES COMPLEX

Feature: 10A-427

Date: 5/5/2002

Station: 10A-427

254 10

381 15

508 20

635 25

762 30

889 35

SUBGRADE 2.00" K 317

(IN) (MM) TEST PROFILE

DCP TEST DATA

Project: SECURITY FORCES COMPLEX

Feature: 10A-427

Station: 10A-427

254 10

381 15

508 20

635 25

762 30

889 35

SUBGRADE 5.75" CBR 8

UNASSIGNED 5.75" CBR 7

UNASSIGNED 1.00" CBR 5

(IN) (MM) TEST PROFILE

DCP TEST DATA

Project: SECURITY FORCES COMPLEX

Feature: 10A-428

Station: 10A-428

254 10

381 15

508 20

635 25

762 30

889 35

SUBGRADE 5.75" K 171

UNASSIGNED 5.75" K 157

UNASSIGNED 1.00" K 134

(IN) (MM) TEST PROFILE

DCP TEST DATA

Project: SECURITY FORCES COMPLEX

Feature: 10A-428

Station: 10A-428

254 10

381 15

508 20

635 25

762 30

889 35

SUBGRADE 5.75" CBR 22

UNASSIGNED 5.75" CBR 19

UNASSIGNED 1.00" CBR 16

(IN) (MM) TEST PROFILE

DCP TEST DATA

Project: SECURITY FORCES COMPLEX

Feature: 10A-433

Station: 10A-433

254 10

381 15

508 20

635 25

762 30

889 35

SUBGRADE 5.75" K 264

UNASSIGNED 5.75" K 284

UNASSIGNED 1.00" K 268

(IN) (MM) TEST PROFILE

DCP TEST DATA

Project: SECURITY FORCES COMPLEX

Feature: 10A-433

Station: 10A-433

GEOTECHNICAL SECTION

CESWF-EC-DG�APPENDIX A�APPENDIX B