Lightweight Concrete

Some of which has been already covered in this thread.

http://cr4.globalspec.com/thread/2346/How-is-Globulite-Manufactured

It used to be that lightweight concrete was primarily a decorative material, using lightweight aggregates, with names like vermiculite, perlite, etc., that took the density of concrete down from about 150 pcf to about 90 pcf, or even lower. It's possible that the newer cements are strong enough to allow some structural applications of lightweight concrete. In any case, check out the Precast Concrete Institute.

I have been seeing the light weight concrete structures from the old archeological structures of the old palaces which are more than 200 years old, in which they used clay hollow tiles, lime and sand. It bears even heavy loads. The new construction contractors, especially in some parts of south india, are approaching the entire work on commercial basis, and charging the rate inclusive of tools and tackles to be purchased or to be rented thus increasing the high expense to the customers. I have been writing some papers on this and I shall be happy to publish purely on friendly basis and would invite your comments. If you have a look for the old structures of Railwy Stations and Rly Quarters, especially in the Eastern Region of India - the british architecture - you would surprise to see its strength preventing leak and water and heat. Shall come back. thank you - Prof. M. Varma

One process for forming light weight concrete panels is to add aluminum powder to the mixed concrete just before pouring onto the form. The high pH cement will act as a catalyst in the wet concrete, allowing the aluminum to steal the oxygen atom from the water molecule, forming aluminum oxide, and releasing hydrogen gas. The hydrogen forms tiny bubbles in the wet mix and the concrete rises like cake batter in an oven. The mix hardens with the voids left by the bubbles intact. The gas leaks out over time. I don't know how these panels rate for load bearing but I'll bet others here can point to that data.

Thanks to all of you sir! Your responses really help me a lot for my research.

Hi dear

i like your idea by add aluminum oxide to concrete and i have research about that ,can give more detailes about this.

my email arafa_bakheet@yahoo.com

You might be interested in looking into the concrete canoe competitions that universities have. In those the concrete is very light, but still structural.

http://www.engr.ncsu.edu/news/awards/conc_canoe.html

Light weight concrete can be used for man purposes. The main constituants are lime and aluminium powder. When the aluminium powder is added to a slurry of lime, hydrogen is produced in the form of bubbles.

Technically it is called as Aluminium aerated cement concrete. A thick slurry is made with lime/cement along with aggregates. A high energy mixer used to stir the contents. Aluminium powder is added in the final stage of mixing. The mix is poured into moulds. The moulds are autoclaved which imparts strength.

Using the blocks for bearing type structure? It is a normal practice to use 'burnt clay bricks for 1+2 floors. The blocks used in this case possess a compressive strength of 60 Kgs/sq cm. Equal or more strength can be obtained in case of aerated concrete. Hence 'technically' there should not be any problem. But the cost of aerated concrete is costly and prohibitive.

Cnurrently aerated concrete is used in places where light weight of the construction is needed and it is used where thermal and acoustic isolation is needed.

I'm a machine designer with 25 years of engineering expertise and I have supplied around 1500 brick units in the past.

TP RAMA CHANDRA RAO

kiranengineers@rediffmail.com vjwtprrao@sancharnet.in

I'm interested in manufacturing blocks (48"X16"x10") with a wight between 50 & 60 pounds ea. I need a density of about 15-20 PCF. I'm trying to use 1 part cement, 2 parts perlite, 4 parts ground strofoam, however I'm not getting a good bond between the foam and concrete,

Any suggestions would be appreciated

In a nutshell: Lightweight concrete for structural applications often contains expanded shale type aggregates and runs 110 to 120 lbs/cu. ft. If the application is primarily insulation (thermal or sound) vermiculites or similar materials are added or agents are used to create foam as alluded to in other posts.

Dear Sir,

refer light weight concrete.

perlite is natural silica matter - expand to 20 times the size

water proofing aggregates as it is similar proprties to glass fibre

it is light weight

fire proof

soundproof for wall.

please communicate further.

Rgds

Sandeep Bhanushali

omegates@yahoo.com