Background
In various parts of the world with appropriate soils, accurately-shaped
cement bricks have been produced by moulding machines of the Cinva-Ram
type to construct low-cost housing. While unskilled labour may be used
to produce these bricks, some degree of skill is required to place the
bricks when building walls. Furthermore, Cinva-Ram bricks are solid and
walls tend to become rather massive for single-storey load-bearing construction
and unstable for a multi-storey construction. In addition, the bricks
require mortar joints for placement, but allow only light reinforcement,
making them unstable in earthquake zones.
Features:
Habitech has developed an interlocking soil cement brick which can be
produced with a modified moulding machine. The presses, made of steel,
can produce three different types of brick: regular, half-size and U-shaped.
The bricks can be made of crushed stone or sand with cement or of earth
stabilized with cement. Soil bricks stabilized with cement and made with
good-quality soil have a wet compressive strength of up to 100 kg./cm2.
The dimensions (10 cm. high x 15 cm. wide x 30 cm. long) of the bricks
are modularly coordinated with other components of the System.
Two types of presses are used for production of interlocking bricks:
manual presses and hydraulic presses. Two persons efficiently operating
a manual press can produce approximately 200-400 bricks per day depending
on the type of raw material used and its availability close to the production
site. In the basic configuration, four manual presses are required. The
hydraulic press can produce around 2000-3000 bricks per day; these bricks
have higher density and greater strength. When crushed stone and cement
are used, resistance of up to 200 kg/cm2 can be achieved. The hydraulic
press hopper is fed by an electric conveyor belt and a concrete mixer.
Advantages
- Interlocking capability. By introducing positive and negative elements
on top and bottom surfaces, bricks can be laid dry and are automatically
aligned when the interlock is completed. Thus, unskilled brick layers
can achieve a higher productivity than skilled masons laying conventional
soil-cement bricks with mortar joints.
- Multi-dimensional capabilities. Since the length of the brick is
twice its width (15 cm. wide x 30 cm. long x 10 cm. high), a right-angle
corner can be achieved without special corner bricks.
- Multi-dimensional capabilities. Since the length of the brick is
twice its width (15 cm. wide x 30 cm. long x 10 cm. high), a right-angle
corner can be achieved without special corner bricks.
- They can be used for T-intersections and cross-intersections, making
possible such configurations as buttresses and solid hollow columns
(which may be filled with reinforced concrete) for multi-storey and
earthquake-reinforced construction.
- Permanent bond capabilities. In lieu of mortar joints, the interlocking
brick uses vertical holes to achieve a permanent bond. The grout holes
are formed by grooves present on all faces of the bricks. These grooves
also lock other elements of the system in place, such as doors and window
frames which use the same grout mixture. The amount of grout is only
7.5 per cent of the mortar used for conventionally laid brick masonry.
The grout mix is poured at regular height intervals during the construction
of the walls.
- Heavy wind and earthquake zone capabilities. The two circular holes
in the bricks permit vertical reinforcement using bamboo or steel at
15 cm. minimum intervals if necessary. Linkage between vertical and
horizontal reinforcement is permitted with the U-shaped brick. The U-shaped
bricks permit horizontal reinforcement at a minimum of 10 cm. interval
if necessary.
- Multi-Storey Construction Capability. Interlocking bricks can duplicate
any conventional brick-laying pattern, while still maintaining continuous
vertical grout and reinforcing holes throughout the height of the wall.
Since the bricks can be laid at right angles to each other, it is possible
to construct walls of multi-brick thickness (wythes) and to place periodic
courses at right angles (headers), to the longitudinally laid brick
courses (stretchers), laid in overlapping (running bond) manner. Provided
unit stress loads are not exceeded, structures of five or six storeys
can be built using a combination of headers and stretchers.
Contact:
Habitech Park
Mr. Bernard Lefebvre
Human Settlements Development Program
Asian Institute of Technology
P.O. Box 4, Khlong Luang,
Pathum Thani 12120, Thailand
Tel: (66-2) 5245611
Fax: (66-2) 5246384
E-mail: bernard@ait.ac.th
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