08-03-2011, 03:19 PM
LIGHTWEIGHT CONCRETE.pptx (Size: 1.07 MB / Downloads: 1,073)
SOME QUESTIONS TO BE ANSWERED
CAN WE SAW CONCRETE ?
ARE THE PRESENT CONCRETE DULL STRUCTURES OUR DESTINY?
IS IT POSSIBLE TO BUILD A BEAUTIFUL CONCRETE STRUCTURE ?
IS IT POSSIBLE TO DECREASE THE SELF WEIGHT OF A STRUCTURAL ELEMENT ?
INTRODUCTION
Concrete is a plastic medium and has incredible potential fINTRODUCTION
or creating fluid, sculptural forms.
It should be admitted that
some of the dullest structures
around us are made of Concrete
but dullness isn't a limitation
inherent in the material.
HISTORY
Lightweight concrete has been used since the eighteen centuries
by the Romans.
In USA and England in the late nineteenth century, clinker was used in their construction for example the ‘British Museum’ and other low cost housing
WHAT IS LIGHTWEIGHT CONCRETE
A type of concrete which includes an expanding agent in that it increases the volume of the mixture while giving additional qualities such as nailability and lessened the dead weight
. It is lighter than the conventional concrete with a dry density of 300 kg/m3 up to 1840 kg/m3 ; 87 to 23%lighter۔
TYPES OF LIGHT WEIGHT AGGREGATE
ARTIFICIAL AGGREGATES
Cinders - Cinders used as aggregates are residues from high-temperature combustion of coal or coke in industrial furnaces. Cinders from other sources are not considered suitable.
Expanded Slag - Expanded slag aggregates are produced by treating blast-furnace slag with water.
Expanded Shale and Clay - All expanded shale and clay aggregates are made by heating prepared materials to the fusion point where they become soft and expand because of entrapped expanding gases
Natural Aggregate
PUMICE:- Pumice is the most widely used of the natural lightweight aggregates. It is a porous, froth-like volcanic glass which is usually white-gray to yellow in color, but may be red, brown, or even black
SCORIA:- Scoria is a vesicular glassy volcanic rock.
VERMICULITE:- Vermiculite is an alteration product of biotite and other micas.
ADVANTAGES
Longer span to be poured unpropped
Faster building rates and lower haulage and handling costs
Larger volumes of LWC can haul economically
Low thermal conductivity
DISADVANTAGES
Very sensitive with water content
Difficult to place and finish
Mixing time is longer
light weight concrete USED IN INDIA
EABASSOC Foamed Concrete is used
Blocks can be made with virtually any dimension
When it rains water does not pass through the foamed concrete
Government of India about light weight concrete