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Solid / Hollow Concrete Blocks

Wednesday 16 January 2008, by Deepa

Concrete Block Technology is based on the principle of densification of a lean concrete mix to make a regular shaped, uniform, high performance masonry unit. Concrete Block Technology can be easily adapted to suit special needs of users by modifying design parameters such as mix proportion, water/cement ratio and type of production system. It is an effective means of utilizing wastes generated by stone crushers, quarrying and stone processing units. The technology has high potential in areas where raw materials are easily available. The Concrete Block Technology package is a highly profitable business for micro and small scale building material producers and construction companies. A total investment of about Rs. 1,75,000/- assures a net profit of approximately Rs. 60,000/- per annum. The market for concrete blocks is growing at a rapid rate, especially in the areas where burnt bricks are not easily available or are of poor quality.

PERFORMANCE

Appearance
Structural Capability
Thermal Properties
Sound Insulation
Fire and Vermin Resistance
Durability and Moisture Resistance
Toxicity and Breath-ability
Sustainability (environmental impacts)
Buildability, Availability and Cost
Applicability

Appearance

Concrete blocks will have a light grey concrete colour, and on close inspection may show a granular texture depending in the type of aggregate used. Machine production provides even finish which offers savings on further cement plaster etc. Concrete blocks can be surface engineered by using pieces of stone or ceramic waste on their face. Another common type is hollow concrete blocks. They are made with a richer mix, but offer a number of advantages, such as lighter weight, easier handling and facility for conducting or reinforcement through the hollows.

Structural Capability

Major advantage of concrete blocks is that their strength can be engineered as per requirement. Thus making them relatively stronger than masonry with bricks walls by around 15-20%. The specifications and the characteristics of a concrete block depend on the machine used to manufacture concrete blocks. The basic raw material is cement, fine aggregate and coarse aggregate. Very little water is used. This is possible only with mechanized compaction and vibration and gives the block high quality in spite of the lean mix, which uses very little cement. These blocks are 4-5 times bigger than burnt bricks; the size of the block or brick used has a bearing on the strength of the masonry. As the bigger size accounts for reduction in the number of mortar joints, thereby increasing wall strength. Weight of a concrete block is about 18-19 Kg’s.

High quality machines provide optimum vibration in the mix so that the ratio of cement used can be reduced substantially without compromising on the strength of the blocks. The machine also compacts and consolidates the mix so that the blocks are uniform in size and attain desired physical properties. 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. The cavities in the blocks provide better thermal protection and also do not need external or internal plastering. The performance of these blocks increases with the increase in the number of hollow cores, which may or may not be filled in with some insulating materials.

Sound Insulation

Concrete blocks provide an acceptable degree of sound insulation.

Fire and Vermin Resistance

Concrete blocks will not burn. They are readily incorporated into fire resistant rated construction. It has no problems of vermin attacks or infestation.

Durability and Moisture Resistance

They are very popular as a long lasting, low maintenance masonry unit, with good compressive strengths. They have a general life’s span 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 of block, after just 24hrs, and may need a weatherproof coating to keep the moisture out.

Toxicity and Breath-ability

Concrete blocks are inert, non-toxic and not prone to off-gassing of volatile materials.

Sustainability (environmental impacts)

Cement contributes maximum to the embodied energy of the product and masonry. Production and application procedures for concrete blocks have been optimized to maximize efficiency of cement use. The emobodied energy in concrete blocks masonry is 270 MJ/Sqm as against 640 MJ/Sqm for brick walls. Therefore concrete blocks, through efficient use of cement, consume less than 50% of the energy, which is consumed by brick walls.

Buildability, Availability and Cost

It has been found that concrete blocks enable savings of approx 8-9% per sq m. of masonry as compared with burnt bricks. This is primarily because of the savings in mortar and faster construction speed, both due to the larger block size and also due to the savings in plaster. Size optimization of concrete blocks also leads to increase in usable internal space, when compared to conventional fired brick construction. Construction techniques involved is similar to other masonry units thus easily adaptable. Through decentralized local production it is easily available through a large number of manufacturers and distributors in most parts of India, in both rural and urban areas.. Cost is almost equal or lesser than an equivalent number of bricks per sq m. of wall.

Applicability

Concrete blocks have various types like; solid, hollow, paving, tree-guard blocks, and each of them are available in various shapes and sizes. This vast range of products offers a large market for application.
- In load bearing structures - low rise residential and office buildings, bungalows, shelter units for rural housing, highway constructions, institutional buildings, godowns and warehouses etc
- In frame structures – High rise residential apartments, office buildings, market complexes, hospitals and hotels etc
- As ground laying units – interlocking paving blocks for roadside walkways, garden pathways, curb stones, exhibition grounds, fuel pumping stations, movement corridors, high traffic movement areas like: bus and train stations etc.
- Specific usage areas: tree guard blocks for roadside and garden tree plantations

Manufacturers

APCO Concrete Blocks and Allied Products

No. 31, Castle Street, Ashok Nagar,

Bangalore - 560 001, India.

E-mail : sales@apcoblocks.com

Mobile : 98450 65712 / 13 / 14 / 15

Website: www.apcoblocks.com

AEON’S Constructions Products Limited

New No: 3, III Street, D-Block, Annanagar (E),

Chennai - 600 102, India.

E-mail: aeons@md3.vsnl.net.in

Phone: 91-44-5217 2400 / 01 / 02

Fax: 91-44-5217 2403

Website: www.aeonsindia.com

Sri Rajendran Concrete Blocks

No 6-A, Maheswari Nagar, 100 Feet Road, Velachery,

Chennai - 600 042, India.

Email: rajendran_concrete@yahoo.com

Phone: 91-44-22453921, 22446595.

Fax: 91-44-2447921.

Website: www.srirajendranconcreteblocks.com