Roller-compacted concrete (RCC) or rolled concrete (Rollcrete) is a special blend of concrete that contains essentially the same ingredients as conventional concrete, but in different proportions and increasingly with partial replacement of fly ash for Portland cement.
It is placed in thin layers to allow full compaction with layer thicknesses ranging from 20 to 30 cm.
Here we will learn about roller compacted concrete, types of roller compacted concrete, advantages & disadvantages of roller compacted concrete.
Introduction to roller compacted concrete:
Roller compacted concrete is a mixture of cement with or without supplementary cementing materials, aggregates and water.
Water content is low than freshly mixed, this concrete looks like damp gravel and it is a zero slump concrete.
For bonding between two layers, segregation must be prevented.
Why roller compacted concrete is preferred:
- This concrete achieves compressive strength from 7 MPa to 30 MPa.
- It is more durable and high resistance to abrasion.
- It has an initial setting time due to less water is required.
Properties of Roller Compacted Concrete:
Strength: It has compressive strength and tensile strength of about 7 to 13 percent like regular concrete, the ratio depends upon the cement content, age, and so on.
Elastic Modulus and Poisson’s Ratio: The RCC mixture has a low elastic modulus because the heat of the generated water is proportional to the elastic modulus.
The RCC mixture has a lower hydration temperature and poisson ratio of about 0.15 to 0.20.
Creep: The creep of the RCC will depend on the aggregate, the water-cement ratio, age, and period of loading.
RCC with excessive compressive strength and low elastic modulus offers high creep.
Lean concrete with large quantities of fine aggregate exhibits high creep.
Thermal Properties: The temperature rise in RCC like a standard concrete mixture depends primarily on the amount of cement used.
All different characters such as specific heat, conductivity, and thermal expansion coefficients are a function of aggregates used within the combination.
Advantages of Roller Compacted Concrete:
- This concrete is cost-effective and fast for construction.
- It requires minimal maintenance.
- No rutting, no potholes.
- Resistance to oil spills, fuels and hydraulic fluids.
- The cost of formwork is minimized or eliminated due to the layer placement method.
- Rebars are not required.
- It provides high quantity placement.
- It doesn’t deform under heavy concentric loads.
- Span soft restricted subgrade.
- It can withstand high temperatures.
- 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.
- Transportation costs, placement, and compaction of concrete are minimized, as a result, the concrete will be handled by dump vehicles; spread by the bulldozers and compressed by vibration rollers.
Disadvantages of Roller Compacted Concrete:
- Although it is used to design RCC dams efficiently, when compared to other dams as the low-cost option, there are situations that can make RCC more expensive.
- When composite materials are usually not accessible, foundation rock is poor or not near to the floor, or the place basis conditions could cause excessive differential settlement.
- Dams repaired or constructed with this concrete could suffer from water leaks, layers of water nonproductive might be considered.
Application of Roller Compacted Concrete:
1. Roller-compacted concrete pavements for highways and streets:
Roller-compact concrete (RCC) is a combination of dense-graded aggregates, portland cement, and water.
This zero deceleration concrete mixture, when placed with an asphalt paver and compacted to excessive density, offers high power, sturdy pavement structure for highways and streets.
RCC makes use of no form, requires no traditional finishing & no dowels or reinforcing steel with no economical alternatives.
The RCC offers superior efficiency under heavy wheel loads, excessive climates and difficult working conditions.
2. Logging Facilities, Composting Areas, and Storage Yards:
This application requires pavement strength and durability to help heavy loads.
Surface look, texture, and smoothness are of little significance for these functions, due to this fact coarse aggregates can be used.
Road rollers and dozers are typically used to position roller-compacted concrete in essentially the most primary functions.
3. Ports, INTERMEDIATE Facilities, and Heavy Industrial Facilities:
Ports and heavy industrial facilities are large, open areas with few boundaries that may delay the development process, making them very best for roller-compacted concrete.
Equipment handling heavy containers will often carry load loads of 13 tons or more.
Traffic speeds are typically 30 mph or less.
4. Light Industrial areas:
Similar to heavy industrial areas, light industrial areas similar to warehouse facilities and auto manufacturing facilities provide massive uninterrupted areas that are perfect for this concrete.
Access roads throughout the industrial complex another utility for roller-compacted concrete.
5. Arterial Streets:
Traffic is always a major concern when paving major paths.
Due to traffic barriers and the time required to place multiple asphalt lifts, some works have chosen to use a single lift of roller compact concrete pavement to pave the major streets.
Roller compact concrete pavements can be constructed faster reducing both project and user costs.
6. Local Streets:
Construction speed, economy and early opening for traffic are important reasons for using roller compact concrete for roads and local roads.
In some cases, light traffic are placed on a roller compact concrete pavement within 24 hours after construction to house near industries.
In addition, using roller compact concrete for new residential development provides a strong working platform during site work and construction.
When traffic speeds exceed 30 mph, surface smoothness is important.
To attain better floor smoothness, most tasks use high-density pavers and/or diamond grinding.
An alternative choice is a thin asphalt surface course positioned on high of roller-compacted concrete.
Also read: Reinforced Cement Concrete, Precast Concrete & Prestressed Concrete
Roller compact concrete is a suitable material that can be used as a surface layer instead of asphalt concrete.