Light weight concrete

Advantages of light weight concrete

•         Reduction in weight on foundation

•         Low thermal conductivity

•         Use of industrial waste

•         Low haulage and handling cost

•         Increase in the speed of construction

Method of production

No fine concrete	Light weight aggregate concrete	Aerated concrete
		Chemical aerating	Foaming mixture
a) Gravel b) Crushed stone c) Coarse clinker d) Sintered     pulverized ash e) Expanded clay     or shale f) Expanded slate g) Foamed slag	a) Clinker b) Foamed slag c) Expanded clay     or shale d) Expanded slate e) Sintered         pulverized ash f) Exfoliated     vermiculite g) Pumice h) Expanded      perlite	a) Aluminum     powder method b) Hydrogen     peroxide and       bleaching powder     method	a) Performed foam b) Air entrained     foam

Light weight aggregate concrete

Natural

1.     Pumice

2.     Diatomite

3.     Scoria

4.     Volcanic cinders

5.     Saw dust

6.     Rice husk

Artificial

1.     Artificial cinders, Coke breeze

2.     Foamed slag

3.     Bloated clay

4.     Brick bats

5.     Sintered fly ash

6.     Exfoliated vermiculite

7.     Expanded perlite

Properties of light weight aggregate concrete

•         Density

•         Strength

•         Workability

•         High and rapidly absorption quality

•         Permeability

•         Durability

•         Thermal conductivity

Typical properties of light weight concrete

Type of concrete	Density of aggregate in Kg/m3	Mix proportion by volume cement: aggregate	Dry density of concrete in Kg/m3	Compressive strength in N/mm2
Foamed slag	900	1:8 1:6	1700 1850	7 21
Expanded clay	100	1:11 1:6	650-1000 1100	3-4 14
Expanded slate	950	1:6 1:4.5	1700 1750	28 35
Sintered fly ash	1050	1:6 1:4.5 1:3.5	1450 1500 1550	28 36 41
Pumice	500-800	1:6 1:4 1:2	1200 1250 1450	14 19 29
Exfoliated vermiculite	65-130	1:6	300-500	2

Aerated concrete

•         By formation of gas by chemical reaction within the mass during liquid or plastic state

•         By mixing preformed stable foam with slurry

•         By adding aluminium powder or hydrogen peroxide and bleaching powder

•         Density 300 to 800 Kg/m³

•         Prefabricated structures and making concrete blocks for load bearing wall.

No Fine concrete

•         Aggregate cement ratio 6:1 to 10:1

•         W/C ratio 0.38 to 0.52

•         Density 1600 to 1900 Kg/m³

•         Compressive strength varies from 2 to 14 N/mm²

•         Very low bond strength

•         Easy compaction

•         Drying shrinkage is low

•         Low thermal conductivity

Pervious Concrete Pavements

•         Pervious concrete pavement is a unique and effective means to meet growing environmental demands.

•         Pervious concrete is a mixture of Portland cement, Coarse aggregates, water. sand is not added.

•         Pervious concrete mass consists of an interconnected void structure. This allows water to seep through at very high speeds.

•         As there is no fine aggregate, void space is between 15-30%.

Ferro cement

•         0.5 to 2.5 mm dia wire mesh at 6 to 75 mm spacing

•         Cement sand ratio 1:2 to 1:3

•         W/C ratio 0.4 to 0.45

•         Thickness 20 to 30 mm with cover of about 2 to 5 mm

•         Steel content 350 to 500 Kg/m³ of concrete

•         Saving in cement and steel

•         Simplicity in construction

•         Lesser dead weight of materials

•         High tensile strength

•         Less crack width as compared to CCC

•         Easy reparirability

•         Non corrosive nature and easier mouldability

Ferro cement and RCC members

Casting techniques

•         Hand plastering

•         Semi mechanized process ( Using hand plastering over form)

•         Centrifuging

•         Guniting

•         Overhead water tank

•         Gas holder tanks in Gobber gas plants

•         Boat building

•         Manhole cover

•         Prefabricated roofs

•         Pressure pipes

•         Curved benches for parks garden and open air cinema theatre

•         Tree guards