Foam concrete (light weight cellular concrete).

Foam concrete(LCC):-
  Foam concrete is also known as light weight cellular concrete (LCC), low density cellular concrete(LDCC).

Foam concrete Define:- a cement based slurry with minimum of 20%(per volume)
Foam entrained into plastic mortor.
    As mostly no coarse agreegate is used to production of foam concrete the correct term would be called mortor instead of concrete it may be called foamed cement.

  HISTORY OF FOAMED CONCRETE:-

The foamed concrete has a long history and it was first made into use in the year 1923. It was initially used as an insulating material. Improvements throughout the past 20 years in the areas of production equipment and better quality foam making agents make the use of foam concrete in large scale.
  A detailed study concerning the composition , physical properties and production of foamed concrete was first carried out in the 1950s and 60s
   Following the reasearch new admixtures were devloped in the late 1970s and rearly 80s which led to commercial use of foamed concrete in construction project

METHOD OF FOAM CONCRETE PRODUCTION:-
       1) Inline method
       2) pre - foam method

1) Inline method of foam concrete production.
    The base mix of cement and sand is added to a unit. In this unit the mix is blended with foam throughly. The process of mixing is carried out with proper control.
This will help in  mixing of larger quantities.
   The larger method comprises two methods:-
       A) wet method - inline system
       B) Dry method - inline system

A wet method in inline system :-

   The material used in wet method will be wetter in nature with the help of series of static inline mixer, the base material and foam are fed and mixed together.
The countinual on  board density monitor used to check the blending of the  whole mix.
  The output volume is drpendent on the density of the foamed concrete and not on the ready mix truck . That is one 8 cumec base material  delivery would produce  35cumec of a foamed concrete of  500 kg/m3  density.

A dry method in inline syatem:-

  Here the dry material are used. There are taken into the onboard silos . From here they are weighed properly and mixed to the onboard  mixer.  The mixed base material are  then pumped to a mixed chamber.
     In wet method of foam concrete production,  foam is added and mixed. The method employs a large amount of  water of mixing . 130 cubic meter foamed concrete  can be produced from a  single delivery of cement  or fly ash cement.

 2) PRE - FOAMED METHOD OF FOAM CONCRETE PRODUCTIION:-

 Here, the ready mix truck brings the base material to the site. Through the other end of truck , the pre - formed foam is injected to the truck, while the mixer is rotating . So small quantities of foam concrete can be produced for small work like grouting  or trench fill work.
  This method would provide foam concrete with densities  ranging from 300 to 1200 kg/m3 . The foam input will be  20 to 60 percentage air. The final volume of the  foam can be calculated  by reducing the amount of  other base material  . As this is carried out  in the truck.
      Control of stable air  and density  is difficult  for this method . So , a degree of under and over  yield must be  specified and allowed  .
   When the foam is formed  it is combined with a cement mortor mix having  water cement ratio of  0.4 to 0.6 . If the mortor is wet , the foam become unstable  if it is to dry, the pre foam is difficult to blend.

ADVANTAGES OF FOAM CONCRETE.

• The foam concrete mix does not settle . Hence it does not need  any compaction
•  The dead weight is reduced  as it is light weight concrete
•  The foamed concrete under its fresh state has freely flowing consistency. This property will help in  complete fillimg void.
•  The foam concrete structure has excellent load spreading  and distributing  capability.
•  Foamed concrete does not impose significant lateral load
• The water absorption property
• The foam concrete batches  are easy to produce , so quality check and control are easily done.
•  The foam concrete has  higher resisting to  freezing and thawing.
•  Non hazardous and faster work completion
• Cost effective , less maintanance.

DISADVANTAGES OF FOAM CONCRETE:-

• Difficulty in finishing.
•  Time of mixing longer
• Presence of water in mixed material make the foam concrete very sensitive.
• With the increase in density the compressive strength and  flexural strength deacrease.

APPLICATION / USES OF FOAMED CONCRETE:-

     A few of  application of foam concrete are:

1. Bridge approches / embankment
2. Pipeline abandonment
3.  Trench backfill
4. Pre cast block
5.  Pre cast wall element
6.  Insulation  floor screed
7.  Insulation roof screed
8.  Sunken portion feeling
9.  Sub base in highway
10.  Filling in hollow blocks
11.  Pre fabricated insulated board