Manoj Kansal

8/2/2019 Manoj Kansal

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Properties of light

weightaggregates

Manoj kansal8ce-030


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Introduction

Light weight aggregate:The aggregates which are light and porous are calledlightweight aggregates. They do not have any crystallizedmineralogical composition. They have a glassy surface,

cellular structure, and can be natural or man-made.

Light weight aggregate concrete:

The concrete made by using lightweight aggregate iscalled lightweight aggregate concrete. It has low densityand strength.


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Natural aggregates

With the increasing demand and the non-availability ofnatural LWAs worldwide, techniques have been developedto produce them in factories. These are produced from thenatural raw materials like expanded clay, shale, slate, etc.,

as well as from industrial by-products such as fly ash, bedash, blast furnace slag, etc

Natural LWA are mostly of volcanic origin and, thus, arefound only in certain parts of the world. Pumice and scoriaare the oldest known LWA; they were used extensively inRoman time. These are light and strong enough to beused in their natural state. Solite and Kenlite also used aslight weight aggregate.


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PumiceThese are volcanic aggregates and are formed when the SiO2-rich moltenlava cools. The molten magma has plenty of air and gases which getentrapped during sudden cooling of the magma. This makes the aggregatesporous. The sudden cooling does not allow the crystallization of theminerals, so it attains glassy structure

1. Main sources are in Europe, Italy, Greece, and Germany

2. low density3. weight reduction of structure and foundation4. reduce dead load5. good insulating properties

ScoriaScoria is a similar material, but it is darker in color than pumice. Itcontains larger and more regular shaped shells that are not connected


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Kenlite

Solite

Pumice Scoria

Scoria


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Palm oil shellsThe use of agriculture waste as aggregates can providean alternative to conventional methods for the productionof lightweight concrete. Palm oil shells are produced inlarge quantities by the oil mills and can be used asaggregates in the production of light weight concrete.properties similar to common aggregate such as clinker,foamed slag, and expended clay.

There are two big advantages:

1.At present they have no commercial value.2.Being locally available, the transport cost is nominal.

It is in the research and development stage


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Synthetic aggregates

Synthetic aggregates are produced by thermal treatmentof the materials which have expansive properties.

Natural materials, such as perlite, vermiculite, clay,

shale, and slate Industrial products, such as glass.

Industrial by-products, like fly ash, expanded slagcinder, bed ash, etc.

The most common types of lightweight aggregatesproduced from

Expansive clays are known as Leca .

fly ash are known as Lytag, etc.


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Palm oil shell

Lytag Leca

Lytag


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Physical properties

Density

Compressive strength

Elasticity

Shrinkage and Creep

Thermal Conductivity

Abrasion Resistance


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Durability to Chemical Attack

Chemical durability is defined as the resistanceof concrete against the gases, chemicals, andtemperature variations which interact chemicallywith the binder components of the concrete

causing deterioration.

Acid Resistance

Alkali Aggregate Reaction Carbonation and Corrosion Chloride Ion Penetration


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Fire Resistance of LWA

One phenomenon that must be considered during fire isthe risk of explosive spelling, which may cause much ofthe concrete cover to disappear leaving the reinforcingbars directly exposed to fire.

Pre-stesses concrete structures with thin webs are moreliable to spelling and explosions, and may collapsesuddenly.

During fire, the water in concrete transforms to steam. Ifthe pore system of concrete is not sufficient to transportthis steam, a pressure builds up and causes spelling ofconcrete.

The addition of polymers and fibers modifies the porestructure and helps in moisture transport. They are aidsfor increasing the fire resistance


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Advantages

Light in weight

Reduce dead load

Low density

Easy to handle

Insulating properties

Heavy tools are not required

Saving enormous expenditure

Demolition cost


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LWAs Savings in

Weight

Money

Time Energy

Transportation cost


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Dulles Airport Terminal Roof


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First National BankOhama , NE


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Conclusion

The successful properties and application oflightweight aggregate demonstrated that itcan be used in building construction to

increase the speed of construction, reducedead load , easy handling , save time,money and energy , enhance green

construction environment and keep dustlevel at construction site to the minimum.


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Thank you

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