CONCRETE AND SOME TYPES OF CONCRETE

concrete is a composite material composed of fine aggregate , coarse aggregate, cement and water.Here are some types of concrete different from normal concrete.

  1. SELF COMPACTING CONCRETE (SCC)
SCC

Self-consolidating concrete or self-compacting concrete (commonly abbreviated to SCC) is a concrete mix which has a low yield stress, high deform-ability, good segregation resistance (prevents separation of particles in the mix), and moderate viscosity (necessary to ensure uniform suspension of solid particles during transportation, placement (without external compaction), and thereafter until the concrete sets).

In everyday terms, when poured, SCC is an extremely fluid mix with the following distinctive practical features — it flows very easily within and around the form work, can flow through obstructions and around corners (“passing ability”), is close to self-leveling (although not actually self-leveling), does not require vibration or tamping after pouring, and follows the shape and surface texture of a mold (or form) very closely once set. As a result, pouring SCC is also much less labor-intensive compared to standard concrete mixes. Once poured, SCC is usually similar to standard concrete in terms of its setting and curing time (gaining strength), and strength. SCC does not use a high proportion of water to become fluid — in fact SCC may contain less water than standard concretes. Instead, SCC gains its fluid properties from an unusually high proportion of fine aggregate, such as sand (typically 50%), combined with plasticizes (additives that ensure particles disperse and do not settle in the fluid mix) and viscosity-enhancing admixtures.

2. ZERO SLUM CONCRETE

We just ran across a requirement for no-slump concrete. What concretes are considered to be no-slump concretes?no-slump concrete is freshly mixed concrete exhibiting a slump of less than 1/4 inch. Zero-slump concrete is defined in the same document, as concrete of stiff or extremely dry consistency showing no measurable slump after removal of the slump cone. And negative-slump concrete is concrete of a consistency such that it not only has zero slump but still has zero slump after additional water is added.

3. PPE FIBRE CONCRETE

Fiber-reinforced concrete (FRC) is concrete containing fibrous material which increases its structural integrity. It contains short discrete fibers that are uniformly distributed and randomly oriented. Fibers include steel fibers, glass fibers, synthetic fibers and natural fibers — each of which lend varying properties to the concrete. In addition, the character of fiber-reinforced concrete changes with varying concretes, fiber materials, geometries, distribution, orientation, and densities. Fibers are usually used in concrete to control cracking due to plastic shrinkage and to drying shrinkage. They also reduce the permeability of concrete and thus reduce bleeding of water. Some types of fibers produce greater impact–, abrasion–, and shatter–resistance in concrete. Generally fibers do not increase the flexural strength of concrete, and so cannot replace moment–resisting or structural steel reinforcement. Indeed, some fibers actually reduce the strength of concrete.

4. DELAY SET CONCRETE

It is nothing just simple concrete but its initial setting time is more than the normal concrete it is done by adding some admixtures to the concrete that will increase the initial setting time of concrete it is important because sometimes it is impossible to produce large amount of concrete at the work site so it is ordered from the RMC plant and concrete has to travel some hours and after that there are certain processes of like loading and unloading so in this whole time the concrete should not initially set and has to be workable so admixtures do this work.

5. LIGHT WEIGHT CONCRETE (LWC)

Light weight concrete is the type of concrete which uses light weight aggregate. Ordinary concrete is quite heavy and its density is 2300 kg/m3. It is not suitable for use in floor filling as filler in general. If used, it adds considerably to the dead weight of the structure. By using suitable aggregates the density of concrete can be reduced. This light weight concrete not only results in reducing dead weights on structure, but also has a better insulation against heat and sound. The strength of such concrete is however low. But it is of no consequence as this concrete is not expected to bear any loads. Because of the light weight, this concrete is very suitable for earthquake proof structures.

Application of Lightweight Concrete

Light weight concrete finds its use generally in situations like:

  • Decks of long span bridges.
  • Fire and corrosion protection.
  • Covering for architectural purposes.
  • Heat insulation on roofs.
  • Insulation of water pipes.
  • Filling for floor and roof slabs.
  • Construction of partition walls and panel walls in framed structures.
  • Production precast building blocks and low cost housing.