Alternate building materials

Need of Alternate Building Materials :

The demand for building materials has been continuously rising with the

increasing need for housing both in rural and urban areas.

The resources used to manufacture construction materials affect the

environment by depleting natural resources, using energy, and releasing

pollutants to the land, water.

Commercial exploitation of traditional building materials by various

industries has aggravated the situation. It has, therefore, become necessary

to think over this problem seriously and to provide some sustainable

solution to make the alternative materials available to solve the housing

problem.

Advantages over Conventional Materials :

1. Better functional efficiency

2. Cost effectiveness

3. Better durability

4. Ease of construction

5. Better finish

6. Minimum waste

7. Less maintenance cost

8. Minimum defects

9. Less energy intensive

List of Alternate Building Materials :

• Hollow Concrete Block

• Fly Ash Bricks

• Rice Husk Ash

• Ferrocement

• Tire Veneer

• Plastic Wood

• Synthetic Fiber

• Recycled Agg.

• Fly Ash

• Bamboo

Hollow Concrete Block (as brick)

Concrete block is primarily used as a building material in the construction of wall. It

is sometimes called a concrete masonry unit (CMU). A concrete block is one of the

several precast concrete products used in the construction (shown as fig.3). The

term precast refer to the fact that the block are formed and hardened before they are

brought to the job site. In use, concrete blocks are stacked one at a time and held

together with fresh concrete mortar to form the desired length and height of the

wall.

Low Maintenance, Color and brilliance of masonry withstands outdoor elements.

Load Bearing, strength can be specified as per the requirement.

Fire Resistant

Provide thermal and sound insulation: The air in hollow of the block, does not allow

outside heat or cold in the house. So it keeps house cool in summer and warm in

winter.

Economical.

Environment Friendly, fly ash used as one of the raw materials.

Advantages

Fly Ash Bricks

Fly Ash bricks are made of fly ash, lime, gypsum and sand. These can be

extensively used in all building constructional activities similar to that of

common burnt clay bricks. The fly ash bricks are comparatively lighter in

weight and stronger than common clay bricks.

Advantages

Saves Construction Cost -: Due to the uniform shape and size of the fly ash brick,

it saves labor in laying bricks by about 15%. This translates into reduction in labor

cost in laying each brick, which is quite substantial.

Less Water Seepage and Dampness in wall -: Due to high strength and less water

absorption of fly ash bricks there are less water seepage and dampness in walls of

building.

Less Energy Consumption -: Huge Energy is consumed in heating clay bricks in

kilns. By using fly ash bricks much energy is saved in brick manufacturing

Reduction in Air Pollution -: Much fossil fuel is used in heating clay bricks in

kilns. Burning such fuel generates air pollution and greenhouse gas (CO2),

contributing to global warming.

Rice Husk Ash / Pozzolanas

Pozzolanas are materials containing reactive silica and/or alumina, which in their

own right have little binding ability. Yet, when mixed with lime and water it will set

and harden like cement. They are important ingredients in alternative cement

compounds. Rice husks are a large by-product – one ton is produces per five ton of

rice paddies, and it is estimated that 120 million tons of husk could be available

annually on a global basis.

Advantages

Increased compressive and flexural strengths.

Reduced permeability.

Increased resistance to chemical attack.

Increased durability.

Reduced effects of alkali-silica reactivity.

Reduced shrinkage due to particle packing, making concrete denser.

Enhanced workability of concrete.

Reduced heat gain through the walls of buildings.

Reduced amount of super plasticizer - Reduced potential for efflorescence

due to reduced calcium hydracids.

Ferrocement

The term ferrocement is most commonly applied to a mixture of Portland Cement

and sand reinforced with layers of woven or expanded steel mesh and closely-

spaced small-diameter steel rods rebar. It can be used to form relatively thin,

compound curved sheets to make hulls for boats, shell roofs, water tanks, etc. When

used in house construction in developing countries, it can provide better resistance

to fire, earthquake, and corrosion than traditional materials, such as wood, adobe

and stone masonry.

Advantages

Low construction material cost -: Ferro-cement construction normally has the

lowest material cost of any of the common vessel construction materials. Typically,

the material cost in ferro-cement is about 30% to 50% of that for steel.

Ease of fairing during construction -: The fairing of the hull form is done during

the plastering stage of construction. This means that the hull framing does not have

to be as accurate as may be required with other common construction materials.

Low ongoing maintenance -: With proper design and construction, ferro-cement

vessels require only minimal ongoing maintenance. If not being moved through the

water, it does not even require antifouling.

Intrinsically safer in the event of grounding -: When subjected to severe impact

(e.g., grounding), ferro-cement does not tear like some other materials. The concrete

cracks but remains mostly secured to the steel mesh substrata. This can restrict the

amount of water that ingresses into the hull.

Long operational life -: Well designed and built ferro-cement vessel has

demonstrated that they have an extremely long economic life. Fifty years or more is

not uncommon.

Tire Veneer (as flooring material)

Rubber tires play an essential role in modern life. Tires are essential globally, at all

levels of development. Millions are discarded annually as they wear out relatively

fast – this product makes use of recycling the material into a usable material for

various types of applications.

Advantages

It is as an environmentally responsive flooring material resilient both indoors

and outdoors.

It can be used in areas such as sports and recreation, animal housing and

high traffic areas outdoors.

A variety of consumer products can be made such as vibration dampeners

and furniture surfaces internally.

Plastic Wood

It is made primarily from high-density polyethylene (HDPE), recovered from the

waste stream mainly in the form of used milk containers or recovered plastic bags,

and from wood wastes (often planer shavings) that have been ground to a fine

powder. A 50:50 mixture of plastic and wood is common. Plastic wood is 100%

recyclable made of recycled plastic.

Advantages

100% resistant to rot.

Impervious to cracking and splitting (with correct installation)

environmentally friendly and requires less maintenance.

Waste plastic and wood is used for manufacturing.

All woods may check, split, cup, crook, twist, and warp, and weather over time

to a grayish color. Treated wood exhibits long-term durability in a deck surface

application, lasting as long, or longer, than naturally durable, untreated woods.

Reinforced Fiber Concrete

Fiber-reinforced concrete (FRC) is concrete containing fibrous material

which increases its structural integrity. It contains short discrete fibers that

are uniformly distributed and randomly oriented. Fibers include steel fibers,

glass fiber, synthetic fibers and natural fibers.

Advantages

Improve mix cohesion, improving pump ability over long distances.

Improve freeze-thaw resistance.

Improve resistance to explosive palling in case of a severe fire.

Improve impact resistance.

Increase resistance to plastic shrinkage during curing.

Improve structural strength and reduce crack widths and control the crack

widths tightly thus improve durability.

Reduce steel reinforcement requirements.

Improve ductility.

Fly Ash

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Advantages

Saves Construction Cost.

Reduction in Air Pollution.

Good Compaction.

High range of OMC.

High internal angle of friction.

Free draining (less interruption due to rain).

No large lumps to be broken (easy to spread).

Light in weight (can be used on weak sub-grades).

Low Cost Housing

Now

Rural House

The house which is to be constructed in rural or village area is called a rural

house. The house can be made cheaply and more efficient with the use of new

alternate materials. In rural house we can use the fly ash brick because it is

cheaply available and more strength. In rural house we can use the mud plaster

because it can resist the temperature variation with tensile property.

Advantages

In this house we can use the timber as beams and columns because it is

easily available in rural area and having more strength.

Plastering can be done with the help of mud.

The construction of house is very cheap.

Prefabricated House

Prefabrication is the practice of assembling components of a structure in a

factory or other manufacturing site, and transporting complete assemblies or

sub-assemblies to the construction site where the structure is to be located. The

term is used to distinguish this process from the more conventional construction

practice of transporting the basic materials to the construction site where all

assembly is carried out. The term prefabrication also applies to the

manufacturing of things other than structures at a fixed site.

Process of Prefabrication

The conventional method of building a house is to transport bricks,

timber, cement, steel and construction aggregate, etc. to the site, and to

construct the house on site from these materials. In prefabricated

construction, only the foundations are constructed in this way, while

sections of walls, floors and roof are prefabricated (assembled) in a factory

(possibly with window and door frames included), transported to the site,

lifted into place by a crane and bolted together.

The method finds application particularly where the structure is

composed of repeating units or forms, or where multiple copies of the same

basic structure are being constructed. Prefabrication avoids the need to

transport so many skilled workers to the construction site, and other

restricting conditions such as a lack of power, lack of water, exposure to

harsh weather or a hazardous environment are avoided.

Advantages

Self-supporting ready-made components are used, so the need for

formwork, shuttering and scaffolding is greatly reduced.

Construction time is reduced and buildings are completed sooner, allowing

an earlier return of the capital invested.

On-site construction and congestion is minimized.

Quality control can be easier in a factory assembly line setting than a

construction site setting.

Prefabrication can be located where skilled labour is more readily available

and costs of labour, power, materials, space and overheads are lower.

Advantages Contd…

Time spent in bad weather or hazardous environments at the construction

site is minimized.

Less waste may be generated and in a factory setting it may be easier to

recycle it back into the manufacturing process, for instance it is less costly

to recycle scrap metal generated in a metal fabrication shop than on the

construction site.

Moulds can be used several times.

Cost Reduction Areas

There are different methods from which cost can be reduced. They

give same advantage i.e. strength while we reduce the cost. Some of them

are :

Plinth

Walling

Doors & Windows

Lintel

Plinth

It is suggested to adopt 1 ft. height above ground level for the

plinth and may be constructed with a cement mortar of 1:6. The plinth slab

of 4” to 6” which is normally adopted can be avoided and in its place brick

on edge can be used for reducing cost. By adopting this procedure the cost

of plinth foundation can be reduced to about 35 to 50% .

Walling

In view of high energy consumption by burnt brick it is suggested

to use concrete block which consumes about only 1/3rd of energy of burnt

bricks in its production and wall thickness can be reduced from 20cm to

15cm. Concrete block masonry saves mortar consumption. Speedy

construction of wall results in higher output of labour. Plastering can be

avoided thereby an overall saving of 10 to 25% can be achieved.

Doors & Windows

It is suggested not to use wood for doors & windows and in its

place concrete or steel section frames shall be used for achieving savings in

cost upto 30 to 40%. Similarly, for shutter commercially available block

boards, fiber or wooden practical boards etc shall be used for reducing the

cost by about 25%.

Lintel

The traditional RCC lintels which are costly can be replaced by

brick arches for small spans and save construction cost upto 30 to 40% over

traditional method of construction. By adopting arches of different shapes a

good architectural pleasing appearance can be given to the external wall

surface of the brick.

Conclusion

The demand for building materials has been continuously rising with the

increasing need for housing both in rural and urban areas.

Selecting environmentally attractive materials with reduced environmental

impacts is primarily achieved through the practice of resource conservation

and selection of non-toxic materials.

The resources used to manufacture construction materials affect the

environment by depleting natural resources, using energy, and releasing

pollutants to the land, water.

Commercial exploitation of traditional building materials by various

industries has aggravated the situation. It has, therefore, become necessary

to think over this problem seriously and to provide some sustainable

solution to make the alternative materials available to solve the housing

problem.

Conclusion Contd…

A review of the recent trends indicates that the growth in the area of

building materials covers emerging trends and latest developments in the

use of wastes, mineral admixtures in cement and concrete, substitutes to

conventional timber, composite materials and recycling of wastes, at the

same time ensuring desired response of materials to fire, long term

performance and durability.

The most important feature governing the choice of material & form of

construction for any component is its structural integrity. Whereas high

specific strength and lightweight were often the dominant criteria to be

achieved, particularly for aerospace applications, there is today an

increasing emphasis on other criteria such as environmental durability,

embedded energy, fire resistance.

4E’s Principle has been followed : -

Efficiency

Economical

Energy Conservative

Eco-friendly

Thus the discussed facts clearly state a

wide and promising scope of Alternate

Building Materials in the Construction

Industry ……