LECTURE - 1
LIGHT WEIGHT CONSTRUCTION MATERIALSUNIT-1LECTURE - 3Brig. S.K.
Sharma (Retd.) Pro Vice Chancellor and Professor Department of
Civil Engineering, The Northcap University, Gurgaon1THE NORTHCAP
UNIVERSITY, GURGAON
INDEXPRODUCTION OF FOAMED CONCRETECONCRETE MIX PROPORTIONSTABLE
OF MIX PROPORTIONS FOR FOAMED CONCRETEWATER-CEMENT RATIOBATCHING OF
MATERIALSFOAM GENERATIONMIXING AND TRANSPORTATIONPLACING OF FOAMED
CONCRETECURING OF FOAMED CONCRETE
2THE NORTHCAP UNIVERSITY, GURGAON
1. CONCRETE MIX PROPORTIONSBased on current knowledge, the
preliminary proportions of ingredients for typical foamed concretes
are given in next slide. The guidelines in the table are intended
to provide an idea of the possible proportions of the mix and
resulting strength characteristics. These mix proportions are in no
way restrictive and there can be numerous designs.
Video: Production from foam concrete blocks (CLC blocks)
PRODUCTION OF FOAMED CONCRETE3THE NORTHCAP UNIVERSITY,
GURGAON
2.Typical mix proportions for Foamed concretes
4THE NORTHCAP UNIVERSITY, GURGAON
3. WATER-CEMENT RATIO On an average, a water-to-cement ratio of
0.40 to 0.45 is normally used. Additional water is added as a
content of the foam, thereby bringing the total water-to-cement
ratio up to the order of 0.6. In general, when the amount of foam
is increased, for lighter densities, the amount of water can
therefore be decreased. However, the water-to-cement ratio should
be kept as low as possible in order to avoid excessive shrinkage.
Tests should be carried out on the mix so that the resulting foamed
concrete will have a flow able, creamy consistency. Some properties
of ingredients are:Sand Clean washed sand of maximum nominal size
of 0.75 mmCement Ordinary Portland cementFoam generated1 cub
m/liter of a typical concentrate5THE NORTHCAP UNIVERSITY,
GURGAON
4. BATCHING OF MATERIALS: Appropriate quantities of sand and
cement are batched, and an amount of water required for the mix to
be flow able is added and materials are mixed thoroughly in a
mixing plant fitted with foam-generating plant and pumping
units.
5. FOAM GENERATION: Foam concentrate, also called foaming agent
is poured into a container typically at one per cent of the
container volume and the container is then filled with clean water,
referred to as dosing water.6THE NORTHCAP UNIVERSITY, GURGAON
6. MIXING AND TRANSPORTATION: In case a ready-mixed concrete,
agitator is used for mixing, all the raw materials are metered into
the agitator (according to mix design specification) and with the
agitator turning at a high speed, a predetermined batched volume of
foam is introduced into the agitator.7. PLACING OF FOAMED CONCRETE:
Properly designed foam concrete has a stable bubble structure and
can be pumped to normal heights without loss of entrained air.
Typically, foam concrete produced and delivered at the site can be
pumped up to a height of 60m.
7THE NORTHCAP UNIVERSITY, GURGAON
8. CURING OF FOAMED CONCRETE: The compressive strength of the
foamed concrete can be significantly increased through an effective
curing process. Moist curing is highly effective in increasing
compressive strength. Some of the commonly used methods of curing
are outlined below:AIR CURING: This is the simplest and most
popular method of curing. It is slow, but acceptable as it enables
a turn around of moulds every 24 hours on an average, depending on
the ambient temperature.STEAM CURING: In case of factory production
a precast foamed- concrete panel or slab is cured by applying steam
to the underside of the mould in order to develop an early strength
and obtain a relatively fast turn-around of moulds.
Video: YouTube, Smart Bricks: A new way to build, 03:25
8THE NORTHCAP UNIVERSITY, GURGAON
Thank You9THE NORTHCAP UNIVERSITY, GURGAON
