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Roller-Compacted Concrete

A Different Kind of Concrete

Freshly placed RCCRoller-compacted concrete, or RCC, takes its name from the construction method used to build it. It's placed with conventional or high-density asphalt paving equipment,then compacted with rollers.

RCC has the same basic ingredient as conventional concrete: cement, water, and aggregates, such as gravel or crushed stone.

But unlike conventional concrete, it's a drier mix—stiff enough to be compacted by vibratory rollers. Typically, RCC is constructed without joints. It needs neither forms nor finishing, nor does it contain dowels or steel reinforcing.

These characteristics make RCC simple, fast, and economical.

 

Tough, Fast, Economical

RCC container facilityThese qualities have taken roller-compacted concrete from specialized applications to mainstream pavement. Today, RCC is used for any type of industrial or heavy-duty pavement. The reason is simple. RCC has the strength and performance of conventional concrete with the economy and simplicity of asphalt. Coupled with long service life and minimal maintenance, RCC's low initial cost adds up to economy and value.


Roots in Logging

Caycuse Log Sort YardRCC got its start in the Seventies, when the Canadian logging industry switched to environmentally cleaner, land-based log-sorting methods. The industry needed a strong pavement to stand up to massive loads and specialized equipment. Yet economy was equally important: log-sorting yards can span 40 acres (16 hectares) or more. RCC met this challenge and has since expanded to other heavy-duty applications.


Durability—even under severe loads— gave RCC pavements their start for log-sorting yards.

Today, RCC is used when strength, durability, and economy are primary needs:
Port, intermodal, and military facilities; parking, storage, and staging areas;
streets, intersections, and low-speed roads.

 

Honda manufacturing plant
Placing RCC at Honda

RCC's economy of scale made it ideal for roads, parking, and staging areas at the Honda Plant in Lincoln, Alabama. At 140 acres, it's the largest RCC pavement project to date.

 

No Rutting, No Pot Holes

The high strength of RCC pavements eliminates common and costly problems traditionally associated with asphalt pavements.
RCC pavements:

  • Resist rutting
  • Span soft localized subgrades
  • Will not deform under heavy, concentrated loads
  • Do not deteriorate from spills of fuels and hydraulic fluids
  • Will not soften under high temperatures

Unique Mix, Unique Construction

RCC pug millRCC owes much of its economy to high-volume, high-speed construction methods.Large-capacity mixers set the pace. Normally, RCC is blended in continuous-mixing pugmills at or near the construction site. These high-output pugmills have the mixing efficiency needed to evenly disperse the relatively small amount of water used.

Dump trucks transport the RCC and discharge it into an asphalt paver, which places the material in layers up to 10 inches (250 mm) thick and 42 feet (13 m) wide.

Compaction is the most important stage of construction: it provides density, strength, smoothness, and surface texture. Compaction begins immediately after placement and continues until the pavement meets density requirements.

Curing ensures a strong and durable pavement. As with any type of concrete, curing makes Compacting RCCmoisture available for hydration—the chemical reaction that causes concrete to harden and gain strength. A water cure sprays or irrigates the pavement to keep it moist. A spray-on membrane can also be used to seal moisture inside.

Completed RCC surfaceWhen appearance is important, joints can be saw cut into the RCC to control crack location. If economy outweighs appearance, the RCC is allowed to crack naturally.

Once cured, the pavement is ready for use. An asphalt surface is sometimes applied for greater smoothness or as a riding surface for high-speed traffic.

 

Economy. Performance. Versatility. RTG Crane on RCC

For RCC, economy was the mother of invention. The need for a low-cost, high-volume material for industrial pavements led to its development.

Low cost continues to draw engineers, owners, and construction managers to RCC. But today's RCC owes much of its appeal to performance: The strength to withstand heavy and specialized loads; the durability to resist freeze-thaw damage; and the versatility to take on a wide variety of paving applications. From container ports to parking lots, RCC is the right choice for tough duty.

Roller-Compacted Concrete (RCC) Performance

 

CONCRETE PERFORMANCE

Features

Benefits

High flexural strength
(500 to 1000 psi) (3.5 MPa to 7.0 MPa)

Supports heavy, repetitive loads without failure and spans localized soft subgrade areas, whichreduces maintenance costs and down time.

High compressive strength (4,000 to 10,000 psi) (28 MPa to 69 MPa)

Withstands high concentrated loads and impacts from heavy industrial, military, and mining applications.

High shear strength

Eliminates rutting and subsequent repairs.

High density, low absorption

Provides excellent durability, even under freeze-thaw conditions; eliminates seepage through pavement.

Low water content, low water/cement ratio

Increases strength, reduces permeability, and enhances durability and resistance to chemical attack.

Aggregate interlock

Provides high shear resistance at joints and uncontrolled cracks to prevent vertical displacement or faulting.

No steel reinforcing or dowels

Speeds and simplifies construction, reduces costs.

No forms or finishing

Speeds construction, reduces cost, minimizes labor.

No formed or sawed joints

Speeds construction, reduces cost. (To enhance appearance, joints can be sawn into RCC pavement.)

Hard, durable, light-colored surface

Resists abrasion, eliminates need for surface course and reduces cost. The light color reduces lighting requirements for parking and storage areas.

 

Refinement of Roller-Compacted Concrete Pavement Fatigue Design Life Curves
Principal Investigator: Paul Okamoto/Matt Sheehan


Objectives

Roller Compacted Concrete (RCC) is a zero slump portland cement concrete mixture that is placed with an asphalt concrete paver and compacted with vibratory and rubber-tired rollers. The concept of RCC pavements originated in Canada during the mid-1970’s for use in log-sorting applications where roads are subjected to relatively heavy loads. Construction of RCC has been expanded to roadways and to container ports, rail terminals, truck terminals, and industrial yards where the pavements are subjected to large forklift trucks, straddle carriers, log stackers, and mobile cranes.


Thickness requirements for RCC pavements are established to minimize flexural fatigue cracking over the design life of the pavement. The number of load repetitions to cracking is determined from a fatigue relationship that incorporates RCC design strength and stress due to vehicle loadings. Commonly, the PCA developed RCC relationship fatigue is utilized in RCC pavement design. This fatigue function, developed by PCA in the mid 1980’s, was based on fatigue testing of 23 beam samples sawed from RCC test slabs. The slabs were constructed using RCC mixes commonly utilized in dam construction. The fatigue function was based on RCC mixes with high coarse aggregate contents, low cementitious contents (approximately 3.2 bag at 17 to 20 percent fly ash substitution), and water cementitious ratios of 0.46 to 0.53. These mixes, representative of those used in dam construction in the early 1980’s, are not representative of mixes used in present RCC pavement construction. The RCC mix formulations have changed and the methods and/or equipment used in RCC batching, placement, and consolidation have changed since the PCA RCC fatigue relationship was developed.


The objective of this project is to refine fatigue curves used in establishing RCC thickness requirements and to develop strength testing procedures for quality assurance. Specifically, the project objectives are to:

 

1. Review fatigue-cracking performance data of RCC pavements that have been subjected to large numbers of load repetitions. It is important to note that it will be difficult to obtain the following information: RCC strength (specified or tested), nominal RCC thickness, magnitude and type of wheel loads, number of daily load repetitions, types of distress (cracking, spalling, shattering) and how this distress is progressing).

 

2. Fabricate RCC beam specimens utilizing different sources of coarse and fine aggregates, different cement contents, and different water-cement ratios. Mixes will be representative of those used in present day RCC pavement construction. Beams will be tested to establish the flexural strength and endurance limit (fatigue life). Mix designs tested will be consistent with what is done in Canada and in the US. In Canada, some beams and cylinders should be based on SEM’s mix design procedure and some others on the method used in Western Canada. Data will be used to refine the PCA RCC fatigue curve utilized in establishing thickness requirements. (Cylinders will also be fabricated and tested to determine the RCC splitting tensile strength, compressive strength, and modulus of elasticity. Cylinder strengths will be correlated with beam strengths.

Correlations will then be used to establish construction quality assurance procedures utilizing cylinder strengths. Data will also be used to establish strength and stiffness characteristics and other structural indices that can be used in current and future pavement design procedures.

 

3. Modifications as a result of the above research will be incorporated into the RCCPave Program (by means of downloadable patch to the program with new fatigue curves).

 

Significance of the Project

Thickness requirements for RCC pavements are established to minimize flexural fatigue cracking over the design life of the pavement. Fatigue performance is primarily a function of RCC flexural strength, slab support (modulus of subbase/subgrade reaction, k), load-induced flexural stresses, and number of load repetitions until cracking. For a given slab thickness, the designer will first calculate load-induced stresses as a function of thickness and design modulus of subbase support (k-value).

 

The number of load repetitions to cracking is then determined from a fatigue relationship as a function of the RCC design strength and calculated stress. If the allowable number of load repetitions calculated from the fatigue relationship is greater than the design number of load repetitions, the slab thickness is sufficient to minimize cracking over the pavement design life. The process can be repeated, increasing or decreasing the slab thickness, until the minimum required thickness is achieved.

 

For a specific project, the designer specifies or estimates the RCC flexural strength and k-value. Load-induced flexural stresses as a function of thickness and design modulus of subbase support can be calculated using PCA’s RCCPave2000 program. The remaining design parameter is the fatigue function relating the number of repetitions until cracking as a function of the calculated stress and specified strength. Commonly, the PCA RCC fatigue is utilized in design. The fatigue curve, developed from RCC mixes typically utilized in dam construction, may not be applicable for RCC utilized in present day pavement construction.

Utilizing a fatigue curve that is not representative of RCC fatigue performance can significantly affect thickness requirements. Based on field observations in Canada and in the U.S., it appears that the fatigue relationship used in the current PCA developed RCC pavement thickness design procedure may be too conservative and does not recognize the improvement in the quality of RCC pavement construction that have taken place in the last 10+ years. If calculated thickness requirements using an inappropriate fatigue curve are too conservative, the pavement thickness may be over designed and material costs are driven up to a point that makes RCC less competitive.


PCA’s RCCPave2000 was used to develop the following example when the current fatigue curve is conservative by 10 percent. A 10 percent shift assumes that for a given number of load repetitions that the allowable stress is actually 10 percent higher than currently allowed. Using the default values in RCCPave2000, for a load-induced stress of 335 psi, the required thickness is 15 in. When the allowable stress is increased by 10 percent to 370 psi, the required thickness is reduced by 14 in. For this example, if the allowable stresses in the present PCA fatigue curve are conservative by 10 percent, the required thickness is conservative by 6 percent. On large industrial projects, a reduction from 15 to 14 in. corresponds to a substantial reduction in construction and material costs.


The refinement of the PCA fatigue curve can result in more optimized design thickness for RCC pavements. This project will refine the current fatigue curve using RCC mixes more representative of those used in current RCC pavement construction in the U.S. and Canada.

 

Project Description

The project will consist of the following four tasks:

  • Task 1 – Review of RCC Fatigue Performance
  • Task 2 – Fatigue Testing and Refinement of PCA Fatigue Curve
  • Task 3 – Development of Inter-Strength Relationships and Quality Assurance Recommendations
  • Task 4 – Final Report

Task 1 – Review of RCC Fatigue Performance

This task involves a review of heavy industrial RCC pavement fatigue performance. The PCA RCC fatigue curve was developed from laboratory testing of RCC beam specimens. The curve was never field calibrated with fatigue cracking performance. A literature and performance documentation review will be made to establish whether the current fatigue curve is conservative or not. This effort will involve gathering of information from recent surveys and discussions with engineers at heavy industrial facilities. Information will include, if available, RCC strength (specified or tested), nominal RCC thickness, magnitude and type of wheel loads, number of daily load repetitions, types of distress (cracking/spalling/shattering), and how fatigue cracking distress, if any, is progressing. Performance data will also be used to evaluate the refined fatigue curve.


We anticipate that much of the data for Task 1 would be forwarded to CTL by PCA/CAC field engineers at no cost to the project. Other data will be gathered from phone conversations with engineers at industrial facilities as well as consulting/design engineers involved with RCC pavement design. Also, a selected number of field visits will be made to obtain more in-depth information, to document the fatigue performance of these projects, and retrieve core samples for strength verification. It is anticipated that site visits will be limited to those where a RCC pavement has exhibited fatigue cracking failure.


A technical summary documenting the results of Task 1 will be prepared for review. This technical summary can be used to identify whether any fatigue cracking problems exists (present fatigue curve not conservative) or no fatigue problems exist (present curve conservative).


Task 2 – Fatigue Testing and Refinement of PCA Fatigue Curve


Task 2 will involve fabrication of beam specimens to be tested in fatigue. RCC mixes with different coarse aggregates, cement contents, and water-cement ratios, representative of those used in present-day construction of RCC pavements, will be batched at CTL. It is anticipated that the fatigue curve and inter-strength correlations will be based on approximately four representative RCC mixes. Using commonly accepted consolidation procedures, RCC will be consolidated into steel beam molds with electrically driven rammers. Beams will be moist cured and tested under repeated loads subjected to different stress magnitudes. It is anticipated that approximately 40 beams will need to be tested in fatigue to develop a statistically significant fatigue curve that can be utilized for design. The number of load repetitions will vary from 1000 to 500,000 load repetitions.

Fatigue data will be analyzed to develop a refined fatigue curve at various levels of reliability. Data from the original PCA fatigue curve may also be incorporated. Developing a set of fatigue curves (Note: There may be the need to develop two separate fatigue curves (one for Western Canada/US the other one for Quebec region) at different levels of reliability will give designers an option to incorporate different levels of risk depending on whether pavement is located in a critical location or not.

 

Task 3 – Development of Inter-Strength Relationships and Quality Assurance Recommendations

Companion cylinders, made from the RCC fatigue mixes, will be tested to establish correlations between beam flexural strength and cylinder compressive/splitting tensile strength. A correlation will enable cylinder, rather than beam tests, to be conducted during construction quality assurance strength testing.

The modulus of elasticity will also be determined to establish a correlation between RCC compressive strength and modulus of elasticity. Data will be used to establish strength and stiffness characteristics and other structural indices that can be used in current and future RCC pavement design procedures.
It is anticipated that approximately 100 cylinders will be fabricated and tested to establish compressive strength, splitting tensile strength, or static modulus of elasticity.

 

Task 4 – Final Report

A draft final report will be prepared documenting all activities conducted in this project, including the results of the fatigue study, recommendations for refined fatigue curves (different levels of reliability), recommendations using of cylinder strengths for quality assurance, quality assurance strength testing guidelines, and RCC strength/stiffness parameters for use in future RCC pavement design. The report will be finalized based on review comments received from PCA.

 

Schedule

The project duration will be 24 months. The work schedule is summarized below:
Task 1 – Revised to February 28, 2004
Task 2 – Revise start date to January 2004
Task 3 – Revise start date to January 2004
Task 4 – December 31, 2004

 

Frequently Asked RCC Questions

Q: What is the proper joint spacing for RCC pavements? (Click for answer)
Q: Why is compaction of RCC so important? (Click for answer)
Q: What types of aggregates can be used to create a quality RCC mix for pavements? (Click for answer)
Q:I know that roller-compacted concrete (RCC) uses the same basic ingredients as conventional concrete – aggregates, water, and cement – but are they mixed together in the same proportions? (Click for answer)
Q: Do you need to cure RCC? (Click for answer)
Q: How does hot weather affect the construction of RCC pavements?
There are two factors that should be considered when evaluating hot-weather construction of RCC pavements: ultimate strength and workability.


Ultimate Strength. The optimal curing temperature for concrete is from 50 degrees F to 70 degrees F. When concrete is cured at temperatures above 80 degrees F the early strengths (1, 3, 7 days) are higher than concrete cured at normal temperatures. However, ultimate strength is reduced. Concrete cured at 90 to 105 degrees F will see 28 day strengths reduced 5 to 15 percent, respectively (Refs 1,2), compared to curing at 73 degrees F.


 

These strength reductions are related to the temperature of curing, not the temperature at placement. With RCC pavements there is a large surface area compared to the concrete thickness, so heat of hydration is not a significant concern. However, the higher placement temperatures will increase evaporative losses, and with the very dry consistency of RCC rapid surface drying and subsequent surface dusting can be an issue during hot weather placement. The use of water curing to keep the RCC surface moist will help to reduce evaporative losses and ensure a strong, durable surface, in addition to reducing the curing temperature.

 

Construction specifications for RCC dams often require that the concrete mix temperature not exceed 80 degrees F (Ref 3). This is to reduce the chance that cracking might occur because of the difference in temperature between the concrete and the ambient air during curing. Methods for reducing the concrete temperature for mass concrete placement include using chilled water, ice chips, cooled aggregate, night placement and liquid nitrogen in extreme cases. The problem with relying on chilled water to cool the RCC is that, unlike conventional concrete, there is generally insufficient water in the mix to make a significant impact on lowering the concrete temperature.

 

Since heat of hydration is not a concern with RCC pavements, a better approach to reduce the temperature of the concrete mix is to cool the coarse aggregate either by shading the aggregate piles or sprinkling the piles with water. The water sprinkling approach also aids in the mixing operation by providing moist aggregate which helps assure a more uniform, consistent mixture.

 

Workability. Hot temperatures will make the concrete less workable and more difficult to place and compact, resulting in a poorer quality final product. High temperatures lead to higher rates of moisture evaporation, which is very important to monitor with RCC because there is so little moisture in the concrete. As temperatures increase from 70 degrees F to 90 degrees F, the time to initial set and final set are reduced by 20 to 30 percent (Ref 4).


When placing RCC during hot weather, it will be to the contractor’s advantage to keep the concrete as cool as possible during placement and compaction. As ambient air temperature increases beyond 90 degrees F, the time allowed from time of mixing to completion of compaction should be reduced accordingly (for example, from 60 minutes to 30 to 45 minutes). To compensate for moisture loss during hauling and placement, additional mix water can be added at the plant. For long haul times, consideration should be given to the use of hydration-stabilizing admixtures to provide more workability time.

 

References

  1. Klieger, Paul, Effect of Mixing and Curing Temperature of Concrete Strength, Research Department Bulletin RX103, Portland Cement Association, 1958
  2. Verbeck, George J., and Helmuth, R. A., “Structures and Physical Properties of Cement Pastes,” Proceedings, Fifth International Symposium on the Chemistry of Cement, Vol III, The Cement Association of Japan, Tokyo, 1968.
  3. Guide for Developing RCC Specifications and Commentary: Roller-Compacted Concrete for Embankment Armoring and Spillway Projects, Portland Cement Association Publication EB214, 2000.
  4. Burg, Ronald G., The Influence of Casting and Curing Temperature on the Properties of Fresh and Hardened Concrete, Research and Development Bulletin RD113T, Portland Cement Association, 1996.

Q: Do you need to cure RCC?
As with conventional concrete, curing is very important for RCC. However, RCC has no bleed water, so the main concern is drying. At least three negative things will happen if RCC is allowed to dry: 1) the concrete will experience drying shrinkage which will lead to cracking, 2) the cement will not continue to hydrate which will result in lower strengths and less durability, especially at the surface, and 3) dusting of the surface is more prevalent.


Curing RCC pavement

 

To keep RCC from drying the surface should be kept moist for 7 days, or until a curing compound is applied. The surface should be gently moistened with water from the time compaction is complete. Curing compounds conforming to ASTM C 309 which are used for conventional concrete can be used for RCC. However, because RCC has a more open texture surface than conventional concrete, the curing compound application rates are 1.5 to 2 times the application rates used for conventional concrete. (See figure) It is good practice to apply the curing compound in two coats with the second coat applied perpendicular to the first.

Other curing techniques such as plastic sheeting and wet burlap are not commonly used for RCC pavements because of the large coverage area; however, for small areas these methods have proved successful. If the RCC is going to be surfaced with asphalt, a bituminous prime coat will also serve as a good curing compound to seal in the moisture. Before placing the RCC it is also important to moisten the base or subgrade material immediately beneath the concrete so that moisture from the concrete is not drawn into the subgrade.

Q:I know that roller-compacted concrete (RCC) uses the same basic ingredients as conventional concrete – aggregates, water, and cement – but are they mixed together in the same proportions?
A: The correct proportioning of the raw materials is critical to the production of quality RCC mixes. The mix design process should not be approached as one of trial and error, but rather a systematic procedure based on the aggregates, water, and cementitious materials used in the mix. This knowledge of the ingredients is coupled with the construction requirements and specifications for the intended project in order to ensure a RCC mix that meets the design and performance objectives.
There currently exists several methods for proportioning RCC mixes for pavements; however, there is not one commonly accepted method. The main RCC proportioning methods include those based on concrete consistency testing, the solid suspension model, the optimal paste volume method, and soil compaction testing. Whichever method is employed, the goal is to produce an RCC mixture that has sufficient paste volume to coat the aggregates in the mix and to fill in the voids between them.

Regardless of which proportioning method is used, it is important that an RCC mixture meet the following requirements:

  • the fine and coarse aggregates should be chosen to achieve the required density and to provide for a smooth, tight surface
  • the moisture content should be such that the mix is dry enough to support the weight of a vibratory roller yet wet enough to ensure an even distribution of the cement paste
  • the cementitious materials used should meet the required design strength requirements at minimal cost

Q:What types of aggregates can be used to create a quality RCC mix for pavements?
A: Because Roller-Compacted Concrete (RCC) uses aggregate sizes often found in conventional concrete, a Ready Mixed Concrete (RMC) producer will probably discover the necessary coarse and fine aggregates for RCC already stored in existing bins or stockpiles. However, the blending of aggregates will be different than what the producer is used to with conventional concrete.

Coarse aggregates consist of crushed or uncrushed gravel or crushed stone while the fine aggregates consist of natural sand, manufactured sand, or a combination of the two. Crushed aggregates typically work better in RCC mixes due to the sharp interlocking edges of the particles, which help to reduce segregation, provide higher strengths, and better aggregate interlock at joints and cracks. Because approximately 80 percent of the volume of a high-quality RCC mix is comprised of coarse and fine aggregates, they should be evaluated as to their durability through standard physical property testing such as those outlined in ASTM C 33.

The American Concrete Institute (ACI) has established aggregate gradation limits that have produced quality RCC pavement mixtures. These ACI gradation limits effectively allow the use of blends of standard size stone, most commonly #67’s, #7’s, #8’s, and #89’s, along with sand, to be used in RCC pavement mixes.

 

Sieve Size

Percent Passing

Inch

Millimeter

Minimum

Maximum

3/4"

19.000

100

100

1/2"

12.500

70

90

3/8”

9.500

60

85

#4

4.750

40

60

#8

2.360

35

55

#16

1.180

20

40

#30

0.600

15

35

#50

0.300

8

20

#100

0.150

6

18

#200

0.075

2

8

Both ACI and the Portland Cement Association (PCA) recommend the use of dense, well-graded blends with a nominal maximum size aggregate (NMSA) not to exceed ¾-inch (19 mm) in order to help minimize segregation and produce a smooth finished surface. Gap-graded mixes that are dominated by two or three aggregate sizes are not desirable for RCC. Additionally, the recommended gradation calls for a content of fine particles (2% to 8% passing the #200 (75 µm) sieve) that is typically higher than that of conventional concrete. This eliminates the need for washed aggregates in many cases and produces a mix that is stable during rolling.

In cases where washed aggregates are being used, it may be difficult to meet the specification for 2% - 8% fine particles. In cases like this, fly ash can be added to the mix to provide the desired fines content. These fines provide lubrication that helps to distribute the paste throughout the mix. However, these fines need to be non-plastic with their Plasticity Index (PI) not to exceed 4.

In many cases, aggregates used in typical highway construction will also meet the RCC gradation requirements mentioned above. Graded aggregate base material, crusher run material, and aggregates for Hot-Mix Asphalt (HMA) paving mixes can be used with little or no modification in RCC mixes.

Close-up of RCC surfacePlacing RCC with paverPlacing RCC with paver

 

 

Roller-Compacted Concrete
Paving Equipment and RCC: The Next Generation?
"Roller-Compacted Concrete, or RCC, takes its name from the construction method used to build it. It’s placed with asphalt paving equipment, then compacted with rollers.” This statement in a PCA promotional publication on RCC could soon face a serious challenge as the advent of new paving equipment makes it possible to place RCC pavements without the need for any additional compactive effort. Newly developed high-power compaction screeds for the drier, stiff concrete mixes typically used in RCC have been used with some success in Europe. Eliminating the need for consolidation using rollers makes this

Paver-Compacted Concrete (PCC) extremely attractive.

According to Siegfried Riffel, who is responsible for project management for traffic route construction with Heidelberg Cement in Germany, these new pavers place, then compact the dry concrete mix from the surface with tamping, vibrating, and pressing compacting systems – achieving the minimum specified density. Densities equal to or greater than the required 98% of a modified Proctor test have been obtained directly out of the back of these pavers resulting in a working width, paving depth, transverse road profile, surface accuracy, and surface texture of the highest possible quality achievable for roadway pavements.

Certain road pavers manufactured by JOSEPH VÖGELE AG based in Mannheim, Germany have been designed to handle and place lean-mixed concrete materials such as conventional RCC mixes. These models include VÖGELE’s SUPER 1600-1, SUPER 1800, and SUPER 2500 which can all be fitted with fixed-width screeds resulting in maximum paving widths from 8 to 16 meters (26 to 52 feet). These screeds are available in different versions depending on their compaction systems. One system, the TVP2, is equipped with a tamper, vibrators, and two pressure bars and is capable of successfully placing RCC mixes at their minimum specified densities without the need for additional compacting using conventional vibratory or static drum rollers.

Mr. Riffel notes that when compared to conventional concrete, PCC placed with these new high-density pavers offers many technical and economic advantages. It is, for example, possible to achieve high quality in terms of strength, durability, and surface finish at relatively low device and personnel costs. The fully mechanical compacting process makes it possible to walk on the surface or lay the second layer with the road paver directly after the high-power compaction screed. Depending on the desired thickness and width of the installation, the concrete can be laid very quickly – from 60 up to 120 meters (approximately 200 to 400 feet) per hour.

RCC at port facilityPCC placed with these next generation pavers has a multitude of potential applications in both private and public roadway construction. It can be placed in single or multiple lifts, most typically in 150 or 200 mm (6 or 8-inch) thickness, and is particularly suitable as either a load-carrying base course or a riding surface. These pavers can place the stiff concrete mix simply, efficiently, and economically and are also suitable for industrial and military streets, airports, bus lanes, road-side rest stops, agricultural and forest tracks, cycle paths, footpaths, intersections, yards, parks, parking lots, industrial flooring, and exhibition areas.


Roller-Compacted Concrete for Ports

Design and Construction of Roller-Compacted Concrete Pavements for Container Terminals
Roller Compacted Concrete (RCC) is a zero-slump concrete consisting of dense-graded aggregate and sand, cementitious materials, and water. The use of RCC as a material to construct pavements began in the 1970’s in Canada. In the past 25 years it has gained acceptance as a strong and durable pavement material that can withstand heavy loads and severe climates with little required maintenance.

The use of RCC for pavements at industrial facilities such as port and intermodal container terminals is particularly appropriate because of the ability to construct low-cost concrete pavements over large areas, allowing flexibility in terminal operations over time. Two basic pavement designs are used which incorporate RCC: 1) unsurfaced, where high-strength concrete is used as the surface layer, and 2) asphalt surfaced, where lower-strength concrete is used as a pavement base and an asphalt layer is used for the wearing surface.

This paper discusses the design concepts for RCC pavements, including the materials characterization, evaluation of loads, and thickness design. Development of the RCC mix design is presented, in addition to important aspects of pavement construction. Performance of RCC pavements at container facilities is evaluated, including existing pavements at the Conley Terminal in Boston, BN Intermodal Terminal in Denver, Pier 300 at the Port of Los Angeles, and the CN Intermodal Terminal in Calgary, Alberta.

The Port of Virginia Builds RCC Pavement for Tough Duty


Finished RCC slab

 

 

Completed RCC slab.

The Virginia Port Authority recently completed construction of a roller-compacted concrete (RCC) pavement for a large container storage and handling area at the Norfolk International Terminals (NIT) in Norfolk, Virginia. This project is part of continuing expansion at the port; currently the 2nd busiest on the east coast in terms of general tonnage. The NIT South Backlands Project – Stage I included 26 acres of RCC pavement 16.5 inches thick (57,300 cubic yards of concrete), topped with 3 inches of asphalt to allow for adjustments to future differential settlement
 


 

Rutting in asphalt pavement caused by channelized loading.

The Norfolk office of Moffatt and Nichol was the engineer for the design and construction of the facility. Pavements for port facilities must be strong and durable because of the heavy loading of the container handling equipment that can have wheel loads of 30-60 kips per tire. In addition, the channelized traffic can cause significant pavement distress.

Because of the large pavement area, cost was a significant factor. Moffatt and Nichol evaluated several possible pavement strategies, including asphalt, conventional concrete, concrete paver blocks, and RCC. An overall evaluation of strength, cost, time of construction, and expected performance resulted in RCC being selected. The design pavement strength was 450 psi flexural strength in 7 days, which related to a construction specification of 2,500 psi compressive strength in 7 days.


The paving contractor for the project was A.G. Peltz Group, Birmingham, Alabama. The mix consisted of 3,470 lbs of dense-graded aggregate (1/2 inch nominal maximum aggregate size) and 400 lbs portland cement per cubic yard. Water content was 6.2% (by weight) of the dry components. The RCC was mixed on-site with an Aran pug mill operating at 400 tons per hour. Three ABG Titan pavers were used during construction. One model 511 with a hydraulic variable screed was used to pave special widths. Another model 511 and a model 525 were used for large area paving, placing concrete 30 feet wide per pull.
The total 16.5 inch RCC thickness was placed in two lifts. Construction specifications called for bonding between the two layers, so the second lift had to be placed within 1 hour of the bottom lift. Quality control procedures included density measurements during compaction, and taking cores to check for bonding, thickness, and strength.


 

Paving top lift within 1 hour of bottom lift placement.

 

Quality control check using pavement cores after 7 days.

The overall experience of the project was positive. The final cost ($42 per square yard) and especially the time required for construction (2.2 days per acre) resulted in a lower cost and faster construction than other comparable paving projects at the NIT. This is not surprising since RCC has been successfully used at the Port of Boston (Conley Terminal), Port of Los Angeles (Pier 300), and for container facilities at rail-truck intermodal yards in Denver, Colorado (Burlington Northern) and Calgary, Alberta (Canadian National). The use of RCC at the NIT is expected to continue, with a project for another 20 acres currently under contract.

 

 

 

 

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Shipping Document Index | Bill of Lading | Bill of Lading Additional Material | Cement Carriers | Certificate of Origin | Certificate of Origin (USA) | Commercial Invoice
Shipping Ports | Ship Classification | SNA Bill of Lading | Lloyds Report

 

Resources

Cement Associations | Cement Equipment | Cement Proposal Documents | Government Standards | University & Library | Cement Industry Links | Shipping Documents
Commodities Exchanges | Newsletters / Magazines