LIGHTWEIGHT CONCRETE

DEFINITION

concrete which uses lightweight aggregates

May consist of lightweight aggregates are used in ordinary concrete of coarse aggregate and sand, clay, foamed slag, clinker, crushed stone, aggregates of organic and inorganic.

Methods of preparation of lightweight concrete

3.Providing lightweight aggregate concrete

1.Preparation of porous concrete2.Without providing concrete smoother (rough concrete)

1.PREPARATION OF POROUS CONCRETE

a) Lightweight concrete obtained by inserting gas bubbles or air into the mixture of plastic cement (mixed with fine sand)

b) Lightweight concrete did not contain stones included as porous mortar.

Characteristics of porous concrete :

2. a high moisture

movement

3. a high shrinkage

1. high thermal

insulation

POROUS CONCRETE

Types of porous concrete

a) type of cast in situ

b) type of first cast

Aggregates used shall comply with the following conditions:

a) At least 95% of

aggregates must be via the 18mm BS sieve.

b) The stone aggregate used

shall not exceed 10% by

10 mm BS sieve.

c) Stone did not diffuse

through the BS 4mm

sieve.

2. Preparation of concrete without the smooth (rough concrete)

Lightweight concrete such as is obtained when the fine aggregate (sand) is not used and the concrete mix of cement, water and coarse aggregates.

Concrete can be used for structural purposes and not to bear burden to bear a load.

3. Preparation of lightweight aggregate concrete

• Concrete is often used in:

a) before pouring the

concrete block

b) the roof and walls cast in

situ for use in insulation.

feature of lightweight aggregate concrete.

The main purpose of the concrete requirements are:

c) have low drying shrinkage (to avoid cracking/rift)

b) have a low density (for

better insulation)

a) has sufficient strength

The above factors depend on:

d) the methods and techniques of preservation

c) the density

b) the mixture

a) types of aggregates

used

Characteristics of Lightweight Concrete

Rain penetration

Water absorption

DurabilityFire insulation

Thermal insulation

Acoustic properties

Thermal insulation

Thermal insulation efficiency is defined as resistance to heat flow either through conduction, or radiation.

Lightweight concrete has a high heat insulation resistance.

such as porous concrete walls 150mm to provide four times better insulation than 225mm thick brick wall.

Fire insulation

• Fire prevention is associated with thermal insulation.

two types of fire

protection

b) a non-combustible materials - such as

non-organic materials such as stone, bricks,

rocks and other.

a) combustible materials - such

as organic wood

Durability

It is defined as the ability to bear the effects of environment such as the effects of chemical, physical stress and mechanical effects. The intended effect of the chemical, including ground water containing sulfate, air pollution and reactive liquid spills.

Physical stress is the shrinkage, the stresses of temperature, cooled, and others. If all the physical stress will cause cracks in the structure of lightweight concrete.

Mechanical effect is the impact and costs are excessive. The situation in the steel structure unit should be protected from rusting.

Water absorption

Absorption water by the concrete is high and more than that found in solid concrete. This is because the lightweight concrete has holes in it.

Penetration of rain water

It is an important element to the wall

Acoustic properties

The key factor is the density of the sound insulation material. Therefore, for sound insulation, lightweight concrete can not show the desired characteristics.

iv) Most of lightweight concrete havebetter nailing and sawing propertiesthan heavier and stronger convensional concrete

iii) Significant reduction of overallweight results in saving structuralframes, footing or piles

ii) Economical in terms oftransportation as well as reductionin manpower

i) rapid and relatively simpleconstruction

Advantages

Disadvantages

iii) Mixing time is longer thanconventional concrete to assureproper mixing

ii) Difficult to place and finishbecause of the porosity andangularity of the aggregate. Insome mixes the cement mortar mayseparate the aggregate and floattowards the surface

i) Very sensitive with water contentin the mixtures

Example :

• ‘The Phantheon’

Lightweight concrete specimen after adhesive tensile test

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