A concrete mix can only be classified as Self Compacting Concrete (SCC) if the same can flow under its weight and completely fill the formwork, even in the presence of dense reinforcement, without any vibration, whilst maintaining homogeneity. Technically, SCC should meet the requirements for filling ability, passing ability and segregation resistance, as mentioned below table:
Roller-Compacted Concrete (RCC) or rolled concrete (rollcrete) is a unique blend of concrete that has essentially the same ingredients as conventional concrete but in different ratios, and increasingly with partial substitution of fly ash for Portland cement. The partial substitution of fly ash for Portland Cement is an essential aspect of RCC dam construction because the heat generated by fly ash hydration is significantly less than the heat generated by Portland Cement hydration. This, in turn, reduces the thermal loads on the dam and minimizes the potential for thermal cracking. RCC is a mix of cement/fly ash, water, sand, aggregate, and common additives but contains much less water. The produced mix is drier and essentially has no slump. RCC is placed like paving; the material is delivered by dump trucks or conveyors, spread by small bulldozers or specially modified asphalt pavers, and then compacted by vibratory rollers
Some of the benefits of using Roller Compacted Concrete are:
- No need to use forms.
- Rebar is not required.
- It provides excellent strength.
- High Volume Placement.
- It can be used as a roadway after only 24 hours of being placed.
- Span soft localized subgrades.
- Will not be affected by oil spills, fuels and/or hydraulic fluids
The drier consistency and lack of fine paste in RCC make its fresh behaviour different from other concretes. This also leads to challenges in characterizing its properties adequately to be translated to practice.
The cohesion, compatibility, segregation resistance, workability retention, water reduction, and consistency constitute the workability of RCC. In association with FC-SETCON R (water-reducing and retarding admixture), FC-PLAST AEA (air entraining agent) offers distinct benefits and improves different properties of fresh RCC, including changing the setting behavior, cohesion, compatibility, consistency, water reduction, and finishibility.
Advantages
- Reduced cement consumption
- Pipe cooling is not required because of the low-temperature rise
- Extended workability during hot weather conditions
Applications
- Irrigation dam construction
- Hydroelectric stations Comply with IS 9103 -1999 and ASTM C 260