Self consolidating concrete wiki
Also, a viscosity-modifying agent(VMA) will be required because slight variations in the amount of water or in the proportions of aggregate and sand will make the SCC unstable, that is, water or slurry may separate from the remaining material.
The powdered materials are fly ash, silica fume, lime stone powder, glass filler and quartzite filler.
To achieve a high workability and avoid obstruction by closely spaced reinforcing, SCC is designed with limits on the nominal maximum size (NMS) of the aggregate, the amount of aggregate, and aggregate grading.
However, when the workability is high, the potential for segregation and loss of entrained air voids increases.
The use of pozzolanic materials helps the SCC to flow better.
HISTORY OF SCC The introduction of the “modern” self-compacting concrete (SCC) is associated with the drive towards better quality of concrete pursued in Japan in late 1980’s, where the lack of uniform and complete compaction had been identified as the primary factor responsible for poor performance of concrete structures.The typical method of compaction, vibration, generates delays and additional cost in the projects.Underwater concreting always required fresh concrete, which could be placed without the need to compaction; in such circumstances vibration had been simply impossible.The SCCs were used under trade names, such as the NVC (Non-vibrated concrete) of Kajima Co., SQC (Super quality concrete) of Maeda Co. Simultaneously with the Japanese developments in the SCC area, R&D continued in mix-design and placing of underwater concrete where new admixtures were producing SCC mixes with performance matching that of the Japanese SCC concrete (e.g. The SCC, as the name suggests, does not require to be vibrated to achieve full compaction.This offers many benefits and advantages over conventional concrete.
Vibrating concrete in congested locations may cause some risk to labour in addition to noise stress.