laterite stone

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Wall Elements for

MasonryCONSTRUCTION BLOCKS

BY RaghuFaculty of Civil Dept DSCE

Raghu Thyagaraj, Asst Prof, Civil Dept,

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Laterite as building material

Laterite is well known in Asian countries as a buildingmaterial for more than 1000 years.

Laterite is a residue ferruginous rock first discovered in the

Malabar region of kerala & Karnataka.

These are highly weathered soils, which contain large,though extremely variable, proportions of iron andaluminium oxides, as well as quartz and other minerals.

The colours can vary from ochre through red, brown, violetto black, depending largely on the concentration of ironoxides.


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The special characteristics of laterites, by which they

differ from other soils, are:

Soft occurrences tend to harden on exposure to air,which is why blocks have traditionally (eg in India)been cut in situ, allowed to harden and then used formasonry wall construction (hence the name wasderived from later,the latin word for brick).

The darker the laterite, the harder, heavier and moreresistant to moisture it is.

Laterite stone-1 Laterite stone-2


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It is full of cavities and pores, and contains a very largequantity of iron in the form of yellow and red ochres. In themass, while excluded from the air, it is so soft, that any iron

instrument readily cuts it, and is dug up in square masseswith a pick-axe, and immediately cut into the shapewanted with a trowel, or large knife.

It very soon after becomes as hard as brick, and resists theair and water much better than any brick that I have seen

in India.

The compressive strength of laterite is around 120Kg/sqcm.

Laterite extraction at site is possible, but the really hardupper layer has to be removed first to reach the soft layers,below. Then the extraction can be done with the locallyavailable tools.


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Hollow Clay blocks

The demand for eco-friendly building materials is on the riseglobally. India, the birthplace of clay brick architecture, still yearnsto go back to the clay days.

A green building leads to the reduction of natural resourceconsumption, reduction of operating costs, energy optimization

and better indoor air quality. By using clay, a 100% natural material,and production practices that have minimal impact onenvironment.

Hollow clay blocks are earthy, season sensible, practical to workwith and bring down your construction cost by more than 15percent

The thermal insulation is twice as good compared to concreteblocks, and the blocks are half the weight of their concretecounterpart


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While a concrete block weighs 30kg, a Porotherm clay

block is only 30kg, making it a light weight for a non-

load bearing wall.

It is available in three sizes. vertical and heavy loadbearing blocks have better insulation properties withgrip holes, making it easier for masons to handle them,

light weight for a non-load bearing wall. Clay hollow bricks have high compressive strength

(>35 kg/cm2)


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Concrete block:

Concrete Block Technology is based on the principle ofdensification of a lean concrete mix to make a regularshaped, uniform, high performance masonry unit.

Concrete Block Technology can be easily adapted to suit

special needs of users by modifying design parameters suchas mix proportion, water/cement ratio and type ofproduction system.

It is an effective means of utilizing wastes generated bystone crushers, quarrying and stone processing units.

Concrete blocks may be produced with hollow centres toreduce weight or improve insulation


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http://en.wikipedia.org/wiki/Building_insulationhttp://en.wikipedia.org/wiki/Building_insulation


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Appearance:

Concrete blocks will have a light grey concrete colour, and

on close inspection may show a granular texture dependingin the type of aggregate used.

Structural Capability : Major advantage of concrete blocks is that their strength

can be engineered as per requirement. Thus making themrelatively stronger than masonry with bricks walls by

around 15-20%.

These blocks are 4-5times bigger than burnt bricks; the size

of the block or brick used has a bearing on the strength ofthe masonry. As the bigger size accounts for reduction in thenumber of mortar joints, thereby increasing wall strength.


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The blocks are cured for a minimum period of 14 days,before they are ready to use.

Thermal properties : Concrete blocks have an excellent thermal property,

comparable to other masonry blocks, as cavities in theblocks provide better thermal protection.

The performance of these blocks increases with theincrease in the number of hollow cores, which may ormay not be filled in with some insulating materials.

Sound insulation : Concrete blocks provide an acceptable degree of sound

insulation.


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Durability and moisture resistance :

They are very popular as a long lasting, lowmaintenance masonry unit, with good compressive

strengths.

They have a general lifesspan of about 60yrs although

may extend up to 80yrs or more. They are robust and durable even if wetted.

It water absorption is less than 10% of weight ofblock.


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Sustainability(environmental impacts) :

Cement contributes maximum to the embodied energyof the product and masonry. Production andapplication procedures for concrete blocks have beenoptimized to maximize efficiency of cement use.

The emobodied energy in concrete blocks masonry is

270MJ/Sqm as against 640MJ/Sqm for brick walls.

Therefore concrete blocks, through efficient use of

cement, consume less than 50%of the energy, which isconsumed by brick walls.


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Buildability, availability and cost :

It has been found that concrete blocks enable savings

of approx 8-9% per sq m. of masonry as compared withburnt bricks. This is primarily because of the savings inmortar and faster construction speed, both due to thelarger block size and also due to the savings in plaster.

Size optimization of concrete blocks also leads toincrease in usable internal space, when compared toconventional fired brick construction.

Through decentralized local production it is easilyavailable through a large number of manufacturersand distributors in most parts of India, in both ruraland urban areas


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Applicability :

Concrete blocks have various types like; solid,hollow, paving, tree-guard blocks, and each of themare available in various shapes and sizes. This vastrange of products offers a large market forapplication.

In load bearing structures - low rise residential andoffice buildings, bungalows, shelter units for ruralhousing, highway constructions, institutionalbuildings, godowns and warehouses etc

In frame structures High rise residentialapartments, office buildings, marketcomplexes,hospitals and hotels etc.


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As ground laying units interlocking paving blocksfor roadside walkways, garden pathways, curb

stones, exhibition grounds, fuel pumping stations,movement corridors, high traffic movement areaslike: bus and train stations etc.

Specific usage areas: tree guard blocks for roadside

and garden tree plantations


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laterite stone