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Roller Compacted Concrete
Roller Compacted Concrete also known as RCC. Roller Compacted Concrete 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.
Roller-compacted concrete 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 roller-compacted concrete simple, fast, and economical.
What Is Roller Compacted Concrete?
Roller-compacted concrete (RCC) is an ultra-tough, zero-slump concrete with compressive strengths greater than 4,000 psi.
It is placed with asphalt pavers to form a nonreinforced concrete pavement. Roller-compacted concrete successfully and economically combines strength and durability with ease of construction.
Roller Compacted Concrete Process
RCC takes its name from the method used to build it.
Mixing of Roller-compacted concrete
- A Roller-compacted concrete (RCC) mixing facility, such as a pug mill, tilt drum, or dry batch ready-mixed plant, must have the efficiency to evenly disperse the relatively small amount of water present in the stiff, dry mix which resembles damp gravel.
Transport of Roller-compacted concrete
- Dump trucks transport the roller-compacted concrete (RCC) mix from the plant to the conventional or high-density asphalt pavers.
Placement of Roller-compacted concrete
- The mix is placed in layers (or lifts) 4-9 inches thick.
Compaction of Roller-compacted concrete
- Steel drum vibratory rollers compact the concrete.
Compaction is the most important step in Roller-compacted concrete (RCC) construction because it provides density, strength, smoothness, and surface texture.
The process begins immediately after placement and continues until the pavement meets density requirements. The pavement must be cured to ensure proper strength gain.
Characteristics of Roller-Compacted Concrete
- Compressive strengths of Roller-compacted concrete (RCC) are usually similar to those of conventional concrete (i.e. 4,000 – 6,000 psi).
- The dense-graded aggregate structure and effectively low water-to-cementitious materials ratio (w/cm) help roller-compacted concrete achieve high compressive strengths.
- Flexural strength is directly related to the density and compressive strength of the Roller compacted concrete mixture.
- In properly constructed Roller Compacted Concrete pavements, the aggregates are densely packed and minimize the development of fatigue cracking.
- The density of the paste and the strength of its bond to the aggregate particles are high due to its low w/cm ratio.
- As a result, the flexural strength of Roller compacted concrete, depending on the mix design, is generally high ranging from 500 to 1,000 psi.
- Based on beams and cores obtained from a test section, the relationship between the compressive and flexural strengths of Roller Compacted Concrete appears to be similar to that for conventional concrete and can be represented by the equation below:
fr = C. fc
fr = Flexural Strength (Third-Point Loading), Psi
fc = Compressive Strength, Psi
C = A Constant Between 9 and 11 Depending on the Actual Roller Compacted Concrete Mix
Modulus of Elasticity
- Modulus of elasticity represents a material’s propensity to undergo reversible elastic deformation in response to stress.
- Limited tests on Roller Compacted Concrete cores obtained from a full-scale test section indicate that Roller Compacted Concrete modulus of elasticity values are similar to or slightly higher than those of conventional concrete when the mixes have similar cement contents.
- The modulus of elasticity expresses the ratio between the applied stress and strain, as shown below:
E = σ / ε
E = Modulus of Elasticity (psi)
σ = Stress (psi)
ε = Strain (in./in.)
- Two sets of roller-compacted concrete (RCC) samples cured for 28 days were subjected to freeze-thaw (F-T) cycles and immersion in laboratory conditions.
- The compressive strength of RCC immersed in KAc solution decreases by 18.8% and 32.8% after 6 and 12 months.
Application of Roller Compacted Concrete
- Today, Roller-compacted concrete is used when strength, speed of construction, durability, and economy are primary needs.
- It is a type of concrete pavement that is well suited for heavy industrial applications, as well as low-speed roads and arterial roads.
- The roller-compacted concrete has been used to construct, repair, or maintenance of the following structures:
List of Application Roller Compacted Concrete
|1||Airfield maintenance areas.|
|4||Industrial and military facilities.|
|5||Industrial slab floors.|
|6||Manufacturing facilities, heavy haul roads, scrap yards.|
|8||New dam construction.|
|10||Parking and storage facilities.|
|12||Power plants and other industrial facilities.|
|13||Rehabilitation of existing dams.|
|16||Streets & highways, intersections, shoulders, turn lanes, and bike paths.|
|17||Sub-base of roads and airfield pavements.|
Roller Compacted Concrete Cost
- The process of Roller compacted concrete itself will reduce your construction costs as there is no need to use forms or rebars, and the application process is very easy and can be done quickly.
- On average, the cost per yard of Roller compacted concrete is about $75 per cubic yard while the cost of Hot-mix Asphalt pavement is about $90 per cubic yard, so you will already notice there are some savings by using Roller compacted concrete.
- Not only that, there are certain products used to improve the Roller compacted concrete surface and applied to the Roller compacted concrete mix such as Roller compacted concrete Surface Pro which improves surface appearance and durability while ACEiT admixture can improve workability.
Benefits of Roller Compacted Concrete
The high strength of Roller compacted concrete pavements eliminates common and costly problems traditionally associated with asphalt pavements.
Some of the benefits of using Roller Compacted Concrete are:
- Roller-compacted concrete provides great strength
- Roller compacted concrete no need to use forms
- In this roller-compacted concrete rebar is not required
- Roller-compacted concrete is high volume placement
- It can be used as a roadway after only 24 hours of being placed
- Will not be affected by oil spills, fuels, and/or hydraulic fluids
- Span soft localized subgrades
- Can withstand high temperatures
Advantages of Roller-Compacted Concrete
- This roller-compacted concrete is cost-effective and has fast construction.
- Roller-compacted concrete requires minimal maintenance.
- Roller compacted concrete plain surface and also no rutting, no potholes.
- The cost of formwork is minimized or eliminated due to the layer placement method.
- Roller-compacted concrete does not deform under heavy concentric loads.
- Also, reduces cement consumption as leaner concrete mixtures may be used.
- There is no concern about the release of high heat during the drying of concrete.
- Roller-compacted concrete resistance to shoving and pushing.
- Transportation costs, placement, and compaction of concrete are minimized, as a result, the concrete will be handled by dump vehicles; spread by bulldozers, and compressed by vibration rollers.
- Shorter haul distance.
- Rapid placement
- Small construction crew
Roller Compacted Concrete Disadvantages
- Smoothness is difficult to achieve.
- Reveling of Cracks.
- Skill person required.
- In roller compacted concrete dams, the drainage gallery often increases construction time and increases costs because the earth fills the method being used does not easily accommodate such a construction.
- Situations, where Roller Compacted Concrete may not be appropriate, are when aggregate material is not reasonably available, the foundation rock is of poor quality or not close to the surface, or where foundation conditions can lead to excessive differential settlement.
- Dams constructed or repaired with roller-compacted concrete may suffer from water seepage. That is why water stoppage layers shall be considered.