Introduction to Self-Compacting Concrete

Self-compacting concrete (SCC) is a highly flowable type of concrete that does not need external vibration for compaction

It is commonly used in construction projects where the use of vibrators for consolidating concrete is challenging. SCC has excellent flowability in its fresh state, allowing it to self-compact and consolidate without any issues of segregation.

Some of the characteristics of self-compacting concrete include filling ability, passing ability, and segregation resistance.

1. Filling ability refers to the concrete's capacity to flow under its weight without any intentional vibration.
2. Passing ability refers to its ability to flow through tight spaces without segregation.
3. Segregation resistance is its ability to withstand segregation during transportation and placement.

The primary ingredients used in the design of self-compacting concrete are cement, aggregates, water, mineral admixtures, and chemical admixtures. The quality of these ingredients is crucial for the concrete's performance.

Cement used for SCC design is typically Ordinary Portland cement, either 43 or 53 grade. The maximum size of aggregates used is 20mm, but it can be reduced to 10-12mm if the reinforcement is closely placed. The best choice for aggregates is well-graded, either round or cubical in shape. The fine aggregates can be either natural or manufactured (M-Sand) with uniform grades, and those with a particle size less than 0.125mm are preferred.

The quality of water used in SCC construction is similar to that of reinforced and prestressed concrete. The type of mineral admixtures used depends on the mix design and desired properties.

Popular mineral admixtures include Ground Granulated Blast Furnace Slag (GGBS), fly ash, silica fumes, and stone powder, each providing specific improvements to the concrete's properties.

Chemical admixtures, such as superplasticizers and air-entraining agents, are commonly used in SCC mix designs to improve its freeze and thaw resistance and control setting time.

The key properties of SCC - filling ability, passing ability, and segregation resistance - are achieved in its fresh state. SCC offers several advantages, such as reduced labour costs, improved quality, reduced noise pollution, and enhanced durability.

Overall, SCC is a highly flowable type of concrete that eliminates the need for external vibration, making it ideal for construction projects where traditional consolidation methods are challenging to implement.

?