Self-levelling concrete (SLC) is a polymer modified high -performance concrete that have the ability to flow, compact and provide a levelled surface when poured over an area. An SLC does not require separate vibration or compaction as required by normal concrete construction.

The basic properties, construction features and benefits of self-levelling concrete are explained in the below section.

Properties of Self-Levelling Concrete

The self-levelling concrete is designed such a way that the following properties are attained:

  1. Low Plastic Viscosity
  2. High Flowability
  3. Low segregation
  4. Low Bleeding
  5. Stability

The low plastic property of SLC increase the flowability properties which imparts the self-levelling property. The balance and proportion of the above-mentioned properties in mix design helps to design the desired SLC concrete.

Providing low viscosity of the concrete mix can result in stability issues. This can result in high segregation and bleeding problens. This low viscosity or high flowability is introduced by the addition of superplasticisers or polymer agents that maintains the stability without affecting the flowability characteristics.

The viscosity agents added prevents the settling down of aggregates that causes segreggation and keep the cohesiveness of the mix within the bond which in turn helps in avoiding bleeding.

High-homogeneity is received by self-levelling concrete with its self-levelling and consolidating property. The flowability properties of self -levelling concrete is greater when compared with self-compacting concrete. This increase in flowability is one reason to obtain good finish in final hardened SLC.

Construction of Self-levelling Concrete Surface

The main two applications of SLC are in the construction of toppings and underlayment. Whatever be the surface under consideration, the SLC mix is initially poured over the surface.

Pouring SLC Mix

Fig.1.Pouring SLC Mix

The highly viscous SLC mix is spread throughout the surface with the help of a gauge rake. Care must be taken not to spread in thin layers.

Spreading SLC with a Gauge Rake

Fig.2.Spreading SLC with a Gauge Rake; Image Courtesy:

A smoother is used later to finish the surface tension over the surface to facilitate finishing process.The polymer addition in the SLC mix helps to maintain the viscosity throughout the layer without letting the aggregates to settle at the bottom.

Advantages of Self-Levelling Concrete

The major advantages of self-levelling concrete are:

  1. Ease of Application
  2. Less labour required
  3. Levelled and smooth surface is obtained
  4. Water Resistant surface is obtained
  5. Resist growth of microorganisms
  6. Best choice of heavily reinforced concrete construction
  7. Hardening of concrete is taking place in a homogeneous way
  8. Best option where formwork is arranged in unusual geometry
  9. Compressive strength higher than traditional concrete is obtained
  10. SLC concrete gives flat and smooth concrete surface
  11. Self-levelling concrete give cohesive concrete that resits bleeding and segregation issues