Alyan Corporation - User's Guide: Resin Modified Pavement

Contents

1. Executive Summary.................................................................................. 1

Description................................................................................................ 1

Applications............................................................................................... 1

Benefits..................................................................................................... 1

Limitations................................................................................................. 2

Costs 2

Recommendations for Use........................................................................... 2

Point of Contact......................................................................................... 3

2. Preacquisition.......................................................................................... 4

Description of Resin Modified Pavement....................................................... 4

Background................................................................................................ 5

Applications............................................................................................... 6

Design Methods.......................................................................................... 6

Materials.................................................................................................... 8

Open-graded AC.................................................................................... 8

Resin modified grout.............................................................................. 9

Construction Techniques........................................................................... 12

Open-graded AC.................................................................................. 12

Resin modified grout............................................................................. 13

Curing................................................................................................. 16

Benefits.................................................................................................... 20

Limitations............................................................................................... 20

Costs 21

3. Acquisition/Procurement......................................................................... 24

Potential Funding Sources.......................................................................... 24

Technology Components and Sources......................................................... 25

Procurement Documents........................................................................... 26

Technical reports................................................................................. 26

Applicable specifications....................................................................... 26

Vendor list and recent prices.................................................................. 26

Procurement Scheduling............................................................................ 27

4. Post Acquisition..................................................................................... 28

Initial Implementation................................................................................ 28

Equipment........................................................................................... 28

Materials............................................................................................. 28

Personnel............................................................................................ 29

Procedure................................................................................................ 29

Operation and Maintenance........................................................................ 30

Service and Support Requirements.............................................................. 30

Performance Monitoring............................................................................ 30

References.................................................................................................... 31

Appendix A: Fact Sheet................................................................................. A1

Appendix B: Guide Specification for Military Construction................................. B1

List of Figures

Figure 1. Schematic of Marsh flow cone................................................... 11

Figure 2. Asphalt paver placing open-graded asphalt mixture........................ 12

Figure 3. Rolling open-graded asphalt mixture with

small roller................................................................................ 13

Figure 4. Catching sample of grout from truck........................................... 14

Figure 5. Filling Marsh flow cone with grout sample................................... 15

Figure 6. Measuring grout viscosity with Marsh flow cone.......................... 16

Figure 7. Pouring grout onto open-graded material...................................... 17

Figure 8. Strips of lumber used to separate grouting lanes............................ 17

Figure 9. Squeegeeing excess grout over open-graded material..................... 18

Figure 10. Small steel wheel roller vibrating grout into voids.......................... 18

Figure 11. Removing excess grout from finished RMP surface...................... 19

Figure 12. Typical appearance of completed RMP surface............................. 19

Figure 13. Comparative pavement thickness profiles and

design costs.............................................................................. 22

List of Tables

Table 1. RMP Project Locations in the United States.................................... 7

Table 2. Open-Graded Mixture Aggregate Gradation.................................... 9

Table 3. Resin Modified Cement Grout Mixture Proportions....................... 10

Table 4. Slurry Grout Viscosity Requirements........................................... 15

1 Executive Summary

Description

Resin modified pavement (RMP) is a composite pavement surfacing that uses a unique combination of asphalt concrete (AC) and portland cement

concrete (PCC) materials in the same layer. The RMP material is generally described as an open-graded asphalt concrete mixture containing 25° to 35°percent voids which are filled with a resin modified portland cement grout. The open-graded asphalt mixture and resin modified cement grout are produced and placed separately. The open-graded mixture is produced in a typical

asphalt concrete plant and placed with standard asphalt paving equipment.

After the open-graded layer has cooled, the slurry grout is poured onto the

porous surfacing and vibrated into the internal voids. The RMP layer is typically 50 mm (2 in.) thick and has a surface appearance similar to a rough-

textured PCC.

Applications

The RMP process is applicable to new pavement construction as well as rehabilitation of existing pavement structures. A new RMP layer may be

placed as an overlay over existing flexible or rigid pavements. The RMP is suitable to carry heavy and abrasive traffic loads and it is resistant to damage from fuel and chemical spills. Successful RMP applications are documented for various low-speed traffic areas, such as airport aprons and taxiways, lowspeed roadways, industrial and warehouse floorings, fuel depots, railways stations, and port facilities.

Benefits

RMP provides a tough and durable pavement surface that resists rutting caused by heavy channelized traffic loads, surface abrasion caused by tracked vehicle traffic, and deterioration due to fuel spillage. The jointless surface is simple to construct and requires little to no maintenance effort. Performance records in the United States indicate that RMP is suitable for practically any environmental condition.

Limitations

RMP should only be used for relatively low-speed traffic applications. The surface texture can be irregular, resulting in areas of variable skid resistance. The irregular surface texture can also be unsightly when compared to a typical PCC surfacing with a relatively uniform surface texture. Construction experience is somewhat limited, which causes paving production rates to start off slowly at the beginning of most projects.

Costs

The cost of a 50°mm°thick RMP layer is currently about $9.60 to 19.20 per square meter ($8 to 16 per square yard) as compared to a typical cost of $3.60 to 6.00 per square meter ($3 to 5 per square yard) for a 50°mm°thick layer of dense-graded AC. The initial cost of a full-depth RMP design is generally 50 to 80 percent higher than a comparable AC design when considering a heavy-duty pavement. A more important cost comparison is between the RMP design and the rigid pavement design, since the RMP is usually used as a cost-saving alternative to the standard PCC pavement. In the case of a standard military heavy-duty pavement application, the RMP design is generally 30 to 60 percent less in initial cost than a comparable PCC pavement design. In many circumstances, the RMP also provides cost savings from reduced or eliminated maintenance efforts when compared to other pavement surfacing alternatives.

Recommendations for Use

RMP is recommended for any newly constructed or rehabilitated pavement carrying low-speed traffic (less than 65 kilometer/hr or 40 mile/hr). RMP can be an ideal cost-saving alternative to PCC pavements where resistance to heavy loads, tracked vehicle traffic, or fuel spillage is required. The available guide specification should be followed closely and the recommended quality control practices should be followed at all times during construction.

2 Preacquisition

Description of Resin Modified Pavement

RMP is a relatively new type of pavement process in the United States that uses a unique combination of AC and PCC materials in the surface layer. The RMP layer is generally described as an open-graded AC mixture containing 25° to 35°percent voids which are filled with a resin modified cement grout. The open-graded asphalt mixture and resin modified cement grout are produced and placed separately. The RMP is typically a 50°mm°thick layer placed on top of a flexible pavement substructure when newly constructed. This same thickness may be placed on existing flexible or rigid pavement structures as well. RMP provides performance benefits attributable to both its AC and PCC material properties at a cost somewhere between the typical AC and PCC ranges.

The open-graded asphalt mixture is designed to be the initial “skeleton” of the RMP. A coarse aggregate gradation with very few fines is used along with a low asphalt cement content (typically 3.5 to 4.5 percent by total weight) to produce 25° to 35°percent voids in the mix after construction. The open-graded asphalt mixture can be produced in either a conventional batch plant or drum-mix plant and is placed with typical AC paving equipment. After placing, the open-graded asphalt material is smoothed over with a minimal number of passes from a small (3°tonne maximum) steel-wheel roller.

The resin modified cement grout is composed of fly ash, silica sand, cement, water, and a cross polymer resin additive. The resin additive is generally composed of five parts water, two parts cross polymer resin of styrene and butadiene, and one part water-reducing agent. The slurry grout water/cement ratio (w/c) is between 0.65 and 0.75, giving the grout a very fluid consistency. The cement grout material can be produced in a conventional concrete batch plant or a small portable mixer. After the asphalt mixture has cooled, the slurry grout is poured onto the open-graded asphalt material and squeegeed over the surface. The slurry grout is then vibrated into the voids with the 3°tonne vibratory steel-wheel roller to ensure full penetration of the grout. This process of grout application and vibration continues until all voids are filled with grout.

Depending upon the specific traffic needs, the freshly grouted surface may be hand broomed or mechanically textured to improve skid resistance. Spray°on curing compounds, typical to the PCC industry, are generally used for short-term curing. The new RMP surfacing usually achieves full strength in 28 days, but it may be opened to pedestrian traffic in 24 hours and light automobile traffic in 3 days.

Background

The RMP process was developed in France in the 1960's as a fuel and abrasion resistant surfacing material. The RMP process, or Salviacim process as it is known in Europe, was developed by the French construction company Jean Lefebvre Enterprises as a cost-effective alternative to PCC (Roffe 1989a). RMP has been successfully marketed throughout France as a pavement and flooring material in numerous applications. By 1990, Jean Lefebvre Enterprises had successfully placed over 8.3 million square meters (10 million square yards) of Salviacim pavement in France (Jean Lefebvre Enterprise 1990). Today, RMP is an accepted standard paving material throughout France.

Soon after the RMP process became successful in France, its use in other countries began to grow. In the 1970's and 1980's, RMP usage spread throughout Europe and into several countries in Africa, the South Pacific, the Far East, and North America (Ahlrich and Anderton 1991a). Twenty-five countries around the world had documented experience with RMP by 1990 (Jean Lefebvre Enterprise 1990).

The earliest documented experience with RMP in the United States occurred in the mid°1970's when the U.S. Army Engineer Waterways Experiment Station (WES) conducted limited evaluations of an RMP test section constructed in Vicksburg, MS (Rone 1976). The study was conducted to evaluate the effectiveness of the new surfacing material to resist damage caused by fuel and oil spillage and abrasion from tracked vehicles. The evaluation results indicated that the effectiveness of the RMP was very construction sensitive, and if all phases of design and construction were not performed correctly, the RMP process would not work.

In 1987, the U.S. Army Corps of Engineers tasked WES to reevaluate the RMP process for potential military pavement applications, since the field experiences in Europe continued to be positive and improved materials and construction procedures had been reported. WES engineers conducted literature reviews, made site evaluations in France, Great Britain, and Australia, and constructed and evaluated a new test section at WES (Ahlrich and Anderton 1991b). The results of this evaluation were favorable, prompting pilot projects at several military installations in the following years. The Federal Aviation Administration (FAA), also eager to develop an alternative paving material technology, used the positive WES experiences and preliminary guidance to construct several pilot projects at commercial airports (Ahlrich and Anderton 1993). Today, the RMP process is recommended as an alternative pavement surfacing material by the U.S. Army, the U.S. Air Force, U.S. Navy, and the FAA.

Applications

RMP may be used in new pavement construction or in the rehabilitation of existing pavement structures. A new RMP surfacing may be placed as an overlay over existing flexible or rigid pavements. RMP is typically used as a low-cost alternative to a PCC rigid pavement or as a means of improving the pavement performance over an AC surfaced flexible pavement. Field experience indicates that RMP may be used in practically any environmental conditions.

In general, the RMP is best suited for pavements that are subjected to low-speed traffic that is channelized or abrasive by nature. Pavement areas with heavy static point loads and heavy fuel spillage are also ideal RMP application candidates. The RMP process has been used in a variety of applications on the international market, including airport and vehicular pavements, industrial and warehouse floorings, fuel depots and commercial gasoline stations, city plazas and malls, railway stations, and port facilities. Since its first commercial application in the Unites States in 1987, RMP has been used mostly on airport and airfield pavement projects. A listing of the known RMP projects in the United States is given in Table 1.

Design Methods

The current practice for designing the RMP layer thicknesses involves a simple adaptation of the standard Corps of Engineers (CE) flexible pavement design method (Headquarters, Departments of the Army and Air Force 1989 and 1992). The pavement is designed as if it were a typical dense-graded AC surfaced pavement, and then the top 50 mm of AC is substituted with an equal thickness of RMP. Equating the RMP material with AC undoubtedly renders an over-designed pavement in terms of the strength and durability provided by the surfacing. A recent study conducted under the Strategic Highway Research Program (SHRP) on potential new bridge deck materials showed that the RMP material had approximately a two-fold increase in Marshall stability, indirect tensile strength, and resilient modulus when compared to a typical high-quality AC material (Al°Qadi, Gouru, and Weyers 1994). Even with the new SHRP results, there are not enough data on the engineering properties of the RMP to develop a suitable mechanistic design methodology. Until such a mechanistic design method is developed, the current method of adapting the results of the standard CE flexible pavement design will continue to be used.

Table 1

RMP Project Locations in the United States

Location

Area (m²)

Date of Construction

Newark Airport, NJ

(Aircraft Apron)

420

May 1987

Springfield, VA

(GSA Parking Lot)

1,670

Oct 1988

Vicksburg, MS

(WES Test Section)

835

Aug 1989

Orange County, CA

(Aircraft Taxiway)

8,350

Oct 1990

Tampa International Airport, FL

(Aircraft Apron)

3,350

Jan 1991

Miami International Airport, FL

(Aircraft Apron)

3,350

Jan 1991

Concord, CA

(Port Facilities)

4,170

70,000

Jun 1991

Oct 1993

1995

McChord AFB, WA

(Loading Facilities)

8,350

Aug 1991

Fort Campbell AAF, KY

(Aircraft Apron)

6,250

Aug 1992

Malmstrom AFB, MT

(Fuel Storage Areas)

10,835

Jun 1993

Fort Belvoir, VA

(Loading Facilities)

8,350

Jun 1994

Pope AFB, NC

(Aircraft Aprons)

29,170

Jun 1994

Altus AFB, OK

(Aircraft Taxiway)

10,500

Jun 1995

RMP has been successfully constructed as an overlay material over rigid and flexible pavements as well as in original construction. No transverse or longitudinal joints are required for original, full-depth RMP designs, although joints have been cut in RMP when overlaying jointed concrete pavement. Pavement joints are required between RMP and adjacent PCC pavements but are not required between RMP and adjacent AC pavements. These joints are constructed by saw cutting to the bottom of the RMP layer, once the RMP material has sufficiently cured, and then filling the joint with a sealant material suitable for the particular site conditions.

Materials

Open graded AC

Aggregates. The aggregates used in the open-graded AC must consist of sound, tough, durable particles crushed and sized to provide a relatively uniform gradation. The aggregates are tested against standard Los Angeles abrasion, sodium sulfate soundness, percent fractured faces, and percent flat and elongated requirements (Headquarters, Department of the Army 1993). These requirements help to ensure a stable, open-graded asphalt layer with a high internal void structure. The general requirement is 25° to 35°percent voids in the compacted mixture. Any amount less than this might not allow the slurry grout to fully penetrate the open-graded mixture, resulting in a structurally unsound surface course which would likely deteriorate under traffic rather quickly. Void contents greater than this amount would increase the cost of the pavement without providing significant structural improvements and could also reduce the pavement strength by eliminating some of the aggregate to aggregate interlock.

Asphalt cement. The type or grade of asphalt cement used in the open-graded AC is not very critical, since the asphalt cement has a limited role in the pavement's performance once the slurry grout has filled all of the void spaces. The asphalt cement is required to be a paving grade material, however, with an original penetration of 40 to 100. Asphalt cements within this penetration range are typically categorized by American Society for Testing and Materials (ASTM) D 3381 as an AC°10, AC°20, or AC°30 viscosity grade (ASTM 1995a). These asphalt cement grades are generally considered to be of medium viscosity. Lower viscosity asphalt cements could drain off of the large aggregates during mixing and transporting, which would reduce the permeability of the open-graded layer and hinder grout penetration. Asphalt cements stiffer (or higher viscosity grade) than the specified range might not allow for sufficient coating of the aggregates with the typical low asphalt contents used.

Mix design. The object of the open-graded AC mix design is to determine an aggregate gradation and asphalt content which will provide a compacted layer containing 25° to 35°percent voids. Sieve analyses of proposed aggregate stockpiles provide the necessary information for an aggregate gradation design. The gradation requirements of the final blended aggregates to be used in the open-graded mixture are given in Table 2.

An estimate of the optimum asphalt content is made to determine a suitable range of asphalt cement contents for a subsequent laboratory analysis. The asphalt content estimate is made using a design equation based on aggregate properties (Roffe 1989b). The design equation is as follows:

Table 2

Open°Graded Mixture Aggregate Gradation

Sieve Size

Percent Passing by Weight

19 mm (3/4 in.)

100

12.5 mm (1/2 in.)

54°76

9.5 mm (3/8 in.)

38°60

4.75 mm (No. 4)

10°26

2.36 mm (No. 8)

8°16

600 μm (No. 30)

4°10

75 μm (No. 200)

1°3

Optimum asphalt content = 3.25 aS^0.2

where

a = 2.65/SG

SG = apparent specific gravity of the combined aggregates

S = conventional specific surface area

= 0.21G + 5.4S + 7.2s + 135f

G = percentage of material retained on 4.75 mm sieve

S = percentage of material passing 4.75 mm sieve and retained on

600 μm sieve

s = percentage of material passing 600 μm sieve and retained on

75 μm sieve

f = percentage of material passing 75 μm sieve

Once the optimum asphalt content is estimated using this equation, two asphalt contents below this amount and two asphalt contents above this amount are used, along with the estimated optimum, in the laboratory production and evaluation of 75°mm (6°in.) diameter Marshall specimens. The open-graded AC specimens are compacted with 25 blows from a 4.5°kg (10°lb) Marshall hand hammer on one side of each specimen. The temperature of the laboratory produced asphalt mixture during compaction is usually around 121 C (250 F). After the laboratory specimens have been compacted and cooled, they are weighed in air and water to determine bulk density and void contents. The optimum asphalt content is typically selected where the resulting void content is nearest to 30 percent.

Resin modified grout

Standard ingredients. The standard ingredients in the resin modified grout include four materials common to PCC production: portland cement, sand, fly ash, and water. No special requirements on portland cement are necessary for a quality grout. A Type I cement should be used unless special conditions require another cement type. A clean, sound, durable, and angular silica sand with a gradation between the 1.18 mm (No. 16) sieve and 75 μm (No. 200) sieve is specified to provide a high quality sand that will stay in suspension in the grout during mixing and application. An ASTM C 618 Type F or “nonhydraulic” fly ash (ASTM 1995b) is used to help provide a consistent grout viscosity without speeding up the grout's rate of setting. Water is added to the grout in an amount that renders a w/c ratio from 0.65 to 0.70. The allowable tolerances for the resin modified grout mix proportions are given in Table 3.

Table 3

Resin Modified Cement Grout Mixture Proportions

Material

Percent by Weight

Type I Cement

34°40

Silica Sand

16°20

Fly Ash

16°20

Water

22°26

Resin Additive

2.5°3.5

Resin additive. The resin additive used in the slurry grout is a proprietary material produced in the United States by the Alyan Corporation under the international trade name Prosalvia°7 or PL7. The additive is generally composed of five parts water, two parts of a cross polymer resin of styrene and butadiene, and one part water reducing agent. The additive significantly aids the construction process by acting as a super-plasticizer in reducing the grout viscosity. The reduced grout viscosity allows the grout to fully penetrate the open-graded asphalt concrete layer more easily. The additive also increases the flexural and compressive strength of the hardened grout, improves the grout's chemical and abrasion resistance, and reduces the grout's permeability after curing.

Mix design. The goal of the slurry grout mix design is to determine the proportions of mix ingredients that will produce a slurry grout of the proper viscosity. Grout viscosity is measured by the Marsh flow cone (schematically shown in Figure 1). The Marsh flow cone is used to measure the time of flux of 1 L (0.264 gal) of grout through the cone. A high flow-time (too thick or viscous) grout does not penetrate the open-graded asphalt layer completely, while a low flow-time grout may not gain sufficient strength and may promote excessive shrinkage cracking and segregation. Grouts with an acceptable initial viscosity will have a flow time between 8.0 and 10.0 sec.

The slurry grout mix design is conducted by preparing individual batch samples in the laboratory and testing them with the Marsh flow cone. The batch samples are prepared by first dry mixing the cement, sand, and fly ash in a blender until thoroughly mixed. The appropriate amount of water is then added, and the grout mixture is blended for 5 min. After the 5°min mixing period, the resin additive is added and mixed with the grout for an additional 3 min. Immediately after the 3°min mixing period, the grout is poured into the Marsh flow cone and tested for viscosity. The individual components of the grout may be adjusted within the prescribed tolerances to obtain a desired flow time.

Construction Techniques

Open°graded AC

The open-graded AC layer is generally produced and constructed in the same manner as conventional AC pavements. The mixture may be produced in either a batch plant or drum-mix plant and is usually mixed at about 121 to 135C (250 to 275F). It is hauled to the construction site in large haul trucks where it is dumped into a standard asphalt paver. The temperature of the open-graded material when being placed is less critical than for standard AC mixtures, since densification is not required. In fact, once the open-graded mixture is placed by the asphalt paver (Figure 2), the surface is simply smoothed over with a small 3°tonne steel wheel roller (Figure 3). Usually, one roller pass when the open-graded material has cooled to about 71 C (160 F) and one roller pass at about 55 C (130 F) is all that is needed to complete the open-graded asphalt construction phase.

Resin modified grout

The resin modified slurry grout material may be produced at a concrete batch plant for larger projects or with portable concrete mixers for smaller projects. For the typical batch plant-produced grout, the proper proportions of cement, sand, fly ash, and water are dumped into transit mix trucks and mixed for 5 min. When the haul distance from the concrete batch plant to the job site is less than 20 min, the cross polymer resin is poured into the mixing drum at the plant site. The slurry grout is continuously mixed in transit and until actual application to prevent the sand material from settling out of the slurry grout mixture. Once the transit mix truck reaches the job site, the mixing drum is rotated at maximum speed for an additional 10 min to ensure complete mixing of the slurry grout. If the haul distance from the concrete batch plant to the job site is greater than 20 min, then the cross polymer resin is added at the job site, followed by an additional 10 min of mixing before application.

Before placement, a sample of grout from each truck is taken and tested against the appropriate Marsh flow cone viscosity requirement (Figures 4, 5, and 6). The appropriate grout viscosity range depends upon the amount of time passed after addition of the resin additive. The slurry grout viscosity requirements are listed in Table 4.

Once the slurry grout has passed the viscosity test, it is poured onto the surface of the open-graded asphalt material from the pivoting delivery chute of the transit mix truck (Figure 7). The slurry grout is applied until the area is

rays. The suggested application rate is 1 L/14 m² (1 gal/400 ft²), which is about one-half of the typical rate used for PCC pavements. Portable hand application of curing compound is allowable immediately after grout placement (when foot tracking is not a problem) since the open-graded asphalt layer provides enough strength to immediately support light loads.

Benefits

RMP provides many of the more attractive benefits associated with both AC and PCC. It offers the ease of construction, the jointless surface, and the cost competitiveness of an AC material. It has the fuel, abrasion, and wear resistance of a PCC. RMP has successfully demonstrated resistance to permanent deformation damage from heavy, high-pressure tire loads. It has also proven its capability in carrying tracked vehicle traffic by resisting the abrasive action of the turning tracks (Ahlrich and Anderton 1991b). The RMP material is well-suited for practically any environment, as evidenced by its international history in regions ranging from the Scandinavian countries to the deserts of Saudi Arabia (Jean Lefebvre Enterprise 1990).

Limitations

RMP should only be used for relatively low-speed (less than 65 km/hr or 40 mile/hr) traffic applications. Initial construction experience indicates that the surface texture of RMP can be irregular, with some areas containing excess grout on the surface. These areas may have a reduced skid resistance, especially at the beginning of the pavement's life. Skid resistance improves during the life of an RMP as surface grout is worn away, exposing the surface of the large-stone open-graded material. When skid resistance is a critical factor, surface texturing (brooming) immediately after grout application has been used successfully.

Because of the fluidity of the slurry grout, it is very difficult to construct an RMP surfacing on steep pavement slopes. The practical limit for the surface slope of an RMP section is 2 percent. Pavement slopes slightly higher than 2 percent can be constructed, but excess hand work and grout overruns are to be expected.

Since the RMP is a relatively new paving process in the United States, the design and construction experience is somewhat limited. As previously discussed, the current thickness design approach is highly empirical with little known about the engineering properties of the RMP material. The lack of construction experience in the United States usually increases the construction time on most projects. Construction and evaluation of test sections are important to ensure that the production of paving materials meets the specified job-mix formulas. Test sections also allow the contractor's paving crews to become familiar with the unique RMP construction techniques. Even with a thorough test section evaluation, full-scale RMP production rates generally start off slowly at the beginning of most projects and increase substantially as the construction process continues.

Costs

The initial construction costs of RMP generally fall somewhere between those of an AC pavement design and a PCC pavement design. In most instances, the RMP pavement design cost will be closer to the AC pavement design cost than to the PCC pavement design cost. Bid experiences from recent RMP construction projects indicate a current cost of about $9.60 to 19.20 per square meter ($8 to $16 per square yard) of 50°mm-thick RMP surfacing.

A cost comparison of AC, PCC, and RMP designs for two hypothetical pavement systems is provided to illustrate the typical differences in first costs for these three pavement types. Pavement designs were conducted using standard CE design methodologies (Headquarters, Departments of the Army and Air Force 1989 and 1992). Flexible and rigid airfield designs were conducted using the following input data:

Design Traffic = C°141 Aircraft at 156,109 kg (345,000 lb)

Design Passes = 100,000

No frost penetration considered

Subgrade California Bearing Ratio (CBR) = 10

Modulus of Subgrade Reaction (K) = 5.5 x 10⁶ kg/m³ (200 lb/in.³)

Subbase CBR = 40

Base CBR = 100

Rigid Design Base Thickness = 200 mm (8 in.)

PCC Flexural Strength = 5.2 MPa (750 lb/in.²)

Flexible and rigid road designs were also conducted for the same conditions, except for the following design parameters:

Traffic Design Index = 8

Base CBR = 80

Rigid Design Base Thickness = 100 mm (4 in.)

The thickness profiles resulting from these hypothetical pavement designs are collectively illustrated in Figure 13.

80 CBR Base = $0.48/sq m

40 CBR Subbase = $0.30/sq m

A quick comparison of the construction costs for these two hypothetical pavement design examples indicates the typical cost of RMP relative to the two standard pavement types: AC and PCC. Cost savings for the RMP designs versus the PCC designs are significant in each of these cases. This cost analysis clearly illustrates a critical design principal for RMP as an alternative pavement surfacing, namely:

When an AC surfacing cannot effectively meet the pavement performance requirements where both an RMP and PCC surfacing can, then the RMP alternative will generally provide significant initial cost savings in terms of total thickness design costs.

In addition to the initial cost savings for using an RMP design instead of a PCC design, an RMP surfacing can be expected to cost much less in terms of maintenance expenditures given a proper design. The most significant maintenance cost savings will result from the lack of joints to maintain and reseal with the typical RMP surfacing. These cost savings will obviously not apply to situations where RMP is overlaid over jointed PCC pavements and joints are cut in the RMP surfacing to trace the PCC joints.

3 Acquisition/Procurement

Potential Funding Sources

Typically, installations fund the implementation of pavements and railroads technologies from their annual budgets. However, the installation's annual budget is usually underfunded and the pavements and railroads projects do not compete well with other high-visibility or high-interest type projects. As a result, it is prudent to seek out additional funding sources when the project merits the action. Listed below are some sources commonly pursued to fund projects.

a. Productivity program. See AR 5°4, Department of the Army Produc

tivity Improvement Program (Headquarters, Department of the Army

1982) forguidance to determine if the project qualifies for this type of

funding.

b. Facilities Engineering Applications Program (FEAP). In the past, a

number of pavement and railroad maintenance projects located at various

installations were funded with FEAP demonstration funds. At that time,

emphasis was placed on demonstrating new technologies to the Director

ate of Engineering and Housing (DEH) community. Now that these

technologies have been demonstrated, the installations will be responsible

for funding their projects through other sources. However, emphasis

concerning the direction of FEAP may change in the future; therefore,

one should not rule out FEAP as a source of funding.

c. Special programs. Examples of these are as follows:

(1) FORSCOM mobilization plan which may include rehabilitation or

enlargement of parking areas and the reinforcement of bridges.

(2) Safety program which may include the repair of unsafe/deteriorated

railroads at crossings and in ammunition storage areas.

(3) Security upgrade which may include the repair or enlargement of

fencing.

d. Reimbursable customer. Examples of this source are roads to special