Making Building Blocks with
the CINVA-Ram Block Press
1600 Wilson Boulevard, Suite
Arlington, Virginia 22209 USA
703/276-1800 . Fax:
This manual was compiled by VITA (Volunteers in Technical
Assistance) from material based on the experience of
several field workers who have used the CINVA-Ram Block
Press. It is hoped
that the manual will make it easier
to use the machine.
VITA would appreciate receiving any
criticisms or suggestions for improving the manual.
Making Building Blocks with
the CINVA-Ram Block Press
Table of Contents
III. TESTING SUITABILITY OF SOIL
IV. MAKING BLOCKS AND TILES
VII. OTHER MACHINES FOR MAKING BLOCKS
FROM STABILIZED EARTH
CHARACTERISTICS OF SOIL-CEMENT
This manual combines the experience of four men who
CINVA-Ram Block Press and figured out answers, bit
by bit, to
the inevitable problems of detail as they came up
day. That was the hard way to learn how
this handbook is intended to make it easier.
The CINVA-Ram Block Press is a simple, low-cost
machine for making building blocks and tiles from
(see Fig. 1). The press, made entirely
has a mold
box in which a hand-operated piston compresses
moistened mixture of soil and cement or lime.
equipment list is on page 3.)
was developed as a tool for small individual
self-help programs. It was designed by
engineer, at the Inter-American Housing
(CINVA) of the Organization of American States
CINVA-Ram blocks and tiles have many
over other building materials.
easier to make than concrete blocks:
be removed immediately from the press
stacked for curing without the use of a
of building material is greatly reduced,
most of the raw material comes from your
**Transportation costs are avoided since the machine
portable and the blocks are made near the construction
on the quality of materials used, CINVA-Ram
can be superior to adobe and rammed
blocks are easily handled.
blocks need no baking, since the curing process
completely natural .
makes variations of the block adapted to
various phases of construction.
Note to the Field Worker
When teaching people how to use
CINVA-Ram Block Press, make your instructions as simple
and clear as possible.
Do not quote from this manual, but
phase of the operation so that you can teach it
in your own
words. Encourage the workers to take
completion of each step, every one of which is a
the final goal.
Soil testing, block production and the use
of the blocks are
important, but they are less important than the will of
families to help themselves in building a home.
to be awakened and supported by your words of
encouragement and inspiration.
Try to make at least one person in the group
operation so that the local community will possess
to carry on the work alone.
CINVA-Ram Block Press
140 lbs. (63 kilos)
and base width:
10" x 16" x 26" (24 x 37 x 64cm)
Application force of lever:
80 lbs. (36 kilos)
Strength (Fully cured blocks)
200-500 psi (14-35 kg/[cm.sup.2])
block (3-1/2" x 5-1/2" x
lays up 4" x 6" x 12"
11-1/2") (9cm x 14cm x 29cm)
(10 x 15 x 30cm)
tile (1-1/2" x 5-1/2" x
lays up 1-1/2" x 6" x 12"
11-1/2" (5cm x 14cm x 29cm)
(5 x 15 x 30cm)
number of blocks or tiles
made by two people per day:
number of blocks needed 2500
number of blocks per 150
100 lbs. of cement:
Inserts: Four different molds
different kinds of blocks and tiles.
in United States: $175 FOB
Warehouse Tallmadge, Ohio
Bellow's Valvair International
200 W. Exchange St.
Akron, Ohio 44309
Apartado Aereo 233-NAL
Materiel Industriel et Menager Japy
6 rue de Marignana
Paris [8.sup.e] FRANCE
Frazer Engineering Company
116 Tuam Street
Christchurch, NEW ZEALAND
Other Equipment Needed
Wide-mouth glass jar
1/4" to 3/8" (6mm to 10mm) mesh wire screen
inside dimensions: 24" x 1-1/2" x 1-1/2"
4cm x 4cm)
mixing boards - good sizes are 4' x 8'
and 8' x
8' (1.2M x 2.5M and 2.5M x 2.5M)
Bottomless measuring box
board at least 9' long, 8" wide and 2" thick
20cm x 5 cm)
at least 1/2" (1.5cm) diameter and 3" (8cm)
III. TESTING FOR THE SUITABILITY OF THE SOIL
Need for Testing
Making blocks from stabilized earth is a
process, but it will not be successful unless the soil
tested. It would be a serious mistake
lightly. Scarce money and labor could
Soil is a variable and complex building
material. Every sample
different from every other sample. But building blocks can
successfully from a wide variety of soils.
Purpose of the Tests
The tests described here will tell us:
How much sand and how much clay is in the soil to
used (Particle Determination Test and Compaction Test,
paragraphs 16 and 17).
How much cement or lime should be added (Box Test,
It is mainly the clay content which gives the mixture
Stabilizer One of the important functions of
is to reduce the change in the volume of the clay, which
it takes up water and then shrinks as it dries.
cement is the best stabilizer, but slaked lime can
used. In some areas, lime is readily
than cement. With lime, a higher
percentage is needed
stabilizing than with cement. Lime does
not work well with
however; careful experimentation is therefore
necessary. Lime can often be
used with excellent results in
with cement. This cuts down on the
needed. But it is important to remember
slowly and therefore needs a longer curing period.
shown good results with 1/3 cement - 2/3 lime mixture.
Organic material is found in the
layer of most soils. Soil used for
block making should be
free of organic matter, which hinders the setting
hardening of the cement and results in weak blocks.
should not be used unless most organic
A wide range of soils is suitable for making blocks.
(1) a good proportion of sand to form the body of
and (2) a certain amount of cohesive or plastic
particles (clay) to bind the sand particles together.
Good blocks can be made with even a
small amount of clay, but
always be some clay. If a small amount
save on cost reducing the amount used.
by testing, because soils commonly considered clay
a good percentage of sand.
Particle Determination Test This test
analyzes the soil to
ratio of sand to clay and/or silt:
the soil through a 1/4" (6mm) screen
Pour into a wide-mouth jar enough soil to fill the
jar half full.
Fill the jar with water and cover it.
Add 2 teaspoons of salt to help the clay/silt
particles settle faster.
Shake the jar vigorously for 2 minutes.
Set the jar on a level spot.
should settle in about half an hour.
quickly to the bottom. The clay/silt
last. Measure the layers to determine
of sand and
clay/silt (see Fig. 2).
that is at least one-third sand and between
5 and 30% Clay/silt.
If the soil at hand is not suitable,
it can be
made suitable by adding sand or clay.
of sand and clay/silt in the soil used.
in deciding which soil makes the best blocks.
Compaction Test. This test
indicates the packing quality of
which depends on the percentage of clay in the
a handful of dry, screened earth and moisten it
until it is damp enough to form a ball when squeezed
the hand, but not so damp that it will leave more
a slight trace of water on the palm.
the ball from a height of about three feet
hard ground. If the ball breaks into a
pieces, the packing quality is good to fair.
disintegrates, the quality is poor.
Box Test The box test is a guide to the
It measures the shrinkage of soil which contains no
stabilizer. The box should have
these inside measurements:
1-1/2" x 1-1/2" (4cm x 4cm x 60 cm) (see Fig. 3).
Oil or grease the
inside surfaces of
the box thoroughly.
Pack the box well
with moist soil
through a 1/4" -3/8"
soil should be
moistened to pack
well, but it should
not be muddy.
Tamp, especially at the corners.
Smooth off the surface with a stick.
Place the box in the sun for three days or in
the shade for seven days. It
should be protected
Measure the contraction (shrinkage) by
pushing the dried
one end of the box.
Cement to Soil Ratio
1/2" (15mm) 1 part
to 18 parts
1/2" and 1" (15mm - 30mm)
1 part to 16 parts
Between 1" and 1-1/2"
(30mm - 45mm) 1 part to 14 parts
1-1/2" and 2" (45mm-60mm)
1 part to 12 parts
is used instead of cement, use double the amount.
Do not use
the soil if it has many cracks (not just three or
it has arched up out of the box; or if it has shrunk
IV. MAKING BLOCKS
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The proportion of cement and/or lime needed
to stabilize the
been determined by the box test.
The number of blocks and tiles needed should
plans for walls and floors. Three
one square foot of wall (33/[m.sup.2]); two tiles give
one square-foot of flooring (22/[m.sup.2].
You may not be present during the
block-making. Go through
with the group doing the work until you are satisfied
steps are clearly understood. Be
Organize the physical layout of the
the operation as efficiently as possible.
the operation should be a flow of work, with
possible number of footsteps, toward the final
near the construction site in the following order:
Digging and screening the soil
Preparing the mixture
Pressing the blocks
Curing and stacking the blocks
Circumstances will not always permit a
direct flow. Therefore,
forethought is needed to set up the best operation for
Digging At the selected excavation spot,
strip the surface
soil of all
vegetation. If the vegetation is
it can be used later for planting around the completed
for replanting the soil supply pit.
The amount of topsoil which must be removed
to avoid getting
matter into the mixture varies in different locations.
It may go
to a surprising depth of several feet, or it may not
necessary to remove any at all.
Normally, six inches
to a foot
(15cm-30cm) should be enough.
Generally the soil gets sandier as the hole
with a low proportion of clay makes the best blocks.
layer of clay subsoil will be followed by very
and combining the two in the screening or mixing
produce a stronger block.
If, as the hole gets deeper, the pit
produces soil which is
for block-making, there is no choice but to enlarge
The person supervising the work will
probably not be present
digging. Therefore he should give a
of soil composition at the start of digging so
pronounced change in sand or clay content will be
In Case of Rain In a period of alternating
showers and sunshine,
should be made to cover the pit (for
with roofing sheets), so that work can continue
after the showers. Where surface water
pit, put up a small retaining barrier of soil.
screened soil should, of course, be protected by a
which will shed most of the rain.
Screening The soil should be
through 1/4" or 3/8"
10mm) wire mesh (see
should be mounted at
where it can be shaken
without back-bending; for
suspending it from
or posts (see Fig. 5).
screening operation is one
and children can help
It is important to keep the CINVA-Ram
not be idle while soil is being dug and screened
Experience is needed to know how large a
earth is needed for different sized buildings.
It can be
estimated, since it will take up 1-1/2 to 1-2/3
volume in the compacted blocks.
Preparing the Mixture
The importance of thoroughness in
mixing and moisture mixing, two distinct steps
preparing the mixture, cannot be emphasized too strongly.
A suitable mixing board (good dimensions:
4' x 8' or
8' x 8' [1.2M x 2.5M or 2.5M x 2.5M]) is needed.
concrete slab or an area of compacted and stabilized
serves equally well.
Measuring boxes whose sizes can be
determined from the
paragraphs 16-19 can be very effective in making
the correct proportions of soil and cement are
Set a large bottomless measuring box on the
Fill it with soil and level off the top.
Lift the box, leaving a measured pile of soil
the board. The soil should be spread
over the mixing board as the box is lifted.
Use a smaller bottomed measuring box for a measured
amount of cement. The cement should
evenly over the soil.
After the proper number of boxes are emptied on
the mixing board, mix the cement and soil by
turning it over with a shovel until it changes
uniformly throughout to a
different shade of color.
Do not use lumpy cement.
Pass it through a fine screen (window
finer); discard lumps which will not break up easily
fingers and pass through the screen.
Spread out the thoroughly
mixed soil-cement mixture
the mixing board.
Add water with a sprinkling
can without making puddles
(see Fig. 6).
Mix it thoroughly again, by
turning it over with a
Keep the amount of water less than what
seems to be enough.
can be mixed in, but much time can be lost in
of excess water.
With a little experimentation it will be
possible to calculate
of water for each mix. This will save
takes to make small additions of water and repeat
process. It is important to remember
will look as though it is not moist enough.
Testing for the Correct Amount
Moisture. The correct amount of
quickly learned through
experience. To test it, squeeze
the mixture. (See Fig. 7.)
If it is
moist enough it will keep the
shape it is
squeezed into. If dropped
onto a hard
surface from shoulder
should break into small
fragments. The mixture is too
if water is
squeezed out of the top
machine box when a block is
The mixture should be used within one hour
Pressing the Blocks
The first point that must be driven home
operators of the CINVA-Ram is that they should not put
strain on the machine when they press a block.
men press on the handle to bring it down in making
block. Nor should anyone jump on the
handle to force it
repeated thrusts of his body. This
point cannot be
emphasized too strongly because such a strain
will damage the
Mounting the Machine
The CINVA-Ram Press (see Fig. 1) should
on a board at least 9' long, 8" wide and 2" thick
20cm x 5cm). A narrower board will let
tip sideways; a shorter board will lift up at the
making it hard to get the right amount of pressure on
a thinner board will split under pressure.
The bolts should be at least one-half inch
in diameter and
inches long (1.5cm x 8cm). It is good
under the heads of the bolts on the underside of
especially on the end of the press with the lower
rollers, since this end receives the
greatest pressure. The
help to keep the bolt head from pulling through the
If the heads do start to pull through,
immediately; the great strain put on a loosely mounted
easily throw it out of adjustment and eventually
sure the piston is all
way down. If it is part
up it will not be possible
get the correct amount
mixture into the box.
the proper amount of
soil-cement mixture into the
(see Fig. 8). The supervisor
should determine the
correct amount of mixture for
block - a measuring box
be used to make sure that
same amount is used each
Uniformity in loading
absolutely necessary for
producing uniform blocks.
the corners of the box to
top so that the corners of
finished block will be well
Press a bit in the corners with
Replace the cover.
the lever to a vertical
position, letting the lower
rollers fall into place
Disengage the lever latch.
the lever to a horizontal
position on the side opposite
cycle) (see Fig. 10). If the
right amount of mixture is used,
man of average weight should
able to move the lever down
alone with only two or three
The lever must be
lowered completely; otherwise the block will be too
thick, wasting material and producing a block which
be too thick to use.
the lever to a vertical position, engage the
lever latch and return the lever to its rest position
the lower rollers.
the cover (see Fig. 11).
Depress the lever steadily to eject the block (see
Fig. 12). If the block is
cracked or deformed, it
should not be used. Read the
instructions in paragraphs
the blocks are lifted from the machine and carried
properly and carefully, and if the mixture is correct
the machine is in good adjustment, the blocks
not break easily.
(a) Press in on opposite ends of the block with
the fingers closed, the
thumbs in close to
the fingers, and using part of the palms
(see Fig. 13).
(b) To set the brick down, tip it into place
on its side.
Try to have at least two men operating the
very time-consuming to have one man moving from one side
machine to the other to press and eject.
But it can be
one man if only one is available. Four
team for pressing: one filling, one pressing, one
and one removing. A team of four can
blocks a minute if the mixture is prepared and
Sticking Some soils stick more than
others. An occasional
of the corners of the press box with a metal scraper
necessary. The blocks should come out
of the press
with sharp corners.
Sticking can be overcome by slightly
moistening the points where it occurs with a bit of kerosene
on a rag.
Rotating Jobs On a job where there is enough
labor to have
steps -- digging, screening, mixing, loading, pressing,
and carrying -- going on at the same time, it is
good for morale to rotate the jobs every hour or so.
Lubrication All moving parts and wearing
pressure plate, guide plates, piston cylinder, bearings
supports of axles) should be well lubricated every
eight hours with heavy oil or grease to insure smooth
and cut down on wear.
Pins The pins which secure the pivot shafts,
rollers should be replaced when broken by the
nails available, because they will last longer than
average cotter pin. If C-ring
replacements are not
available, broken C-rings can be replaced by wrapping a
wire in the groove.
Clean Surfaces The inside of the box and the
of the cover-must be kept clean.
Adjustments The CINVA-Ram press should not
be tampered with
unnecessarily, but the following suggestions
if the press produces faulty blocks.
Breaks and Cracks Breaks and cracks are
caused by loose or
incorrectly adjusted guideplates.
Side Breaks (See Fig. 14.)
lower adjusting bolts
(G and H)
sideways toward the
of the break (see Fig. 1).
adjustment is needed, move
adjusting bolts (E and F)
the low side of the break.
sometimes be done simply
hammering the bolt sideways (with
a piece of wood, so that the threads
be damaged) rather than by
and tightening the nuts.
bolts are hammered over,
End Breaks (See Fig. 15.) Move
plate opposite the end
break occurs inward by
lower adjusting bolt G or
depending on the guide plate to
(See Fig. 1). NOTE: Moving
of a guide plate in one direction forces the other
the same plate in the opposite direction.
the piston much at either the top or the bottom of
plate, the other end of the plate must be moved
inward. The free play should be
corrected because it will
piston to crack the blocks by compressing them
direction in the compression cycle (with the upper
the pivot point) and in another direction in the
cycle (with the lower rollers as the pivot point).
guide plates must be tight enough against the
keep it from jerking and jumping upward at the
end of the
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If end cracking is not stopped by tightening
the piston, it may be necessary to tilt the guide
and the piston, so that the pressure plate will be
the end which is cracking. This is done
the tops of both guide plates toward the cracked end.
Corner Breaks A corner break
by a combination of
break and an end break
Fix the side crack by moving
the bolts sideways, as
paragraph 54 (usually it
only necessary to move the
bottom bolt on the end with the crack toward the
side where the crack occurs).
Fix the end crack by moving the lower adjusting
bolt opposite the cracking end inward against
the piston, as in paragraph 55.
Tapering Tapering is caused by incorrectly
adjusted guide plates.
Side Taper (See Fig. 17.)
move the guide plate
thicker side outward; then
other guide plate inward
1). The guide plates
kept parallel to each
other. Move both the tops and
of both guide plates the
End Taper (See Fig. 18) Move the
tops of both
guide plates toward
end. Move the bottoms of
guide plates toward the thick
Fig. 1) The tops should
as far in one direction as
bottoms are in the other.
Corner Taper (See Fig. 19) A
taper (one corner thinner
rest) is caused by a
combination of a side taper and an
taper. First, fix the side taper
the guide plates as in paragraph
Second, fix the end taper
the guide plates as in paragraph
Curing and Stacking the Blocks The curing of
the blocks is
important step which must be taken with care.
at this point could ruin all the careful work that has
The moisture in the blocks must
slowly and evenly.
The blocks should be laid on
unwarped, clean planks
enough to support the full
the blocks (See Fig. 20)
boards are not available,
blocks should be placed on
ground covered with paper
so that they will not
direct contact with the
The blocks should not be pushed
another position after
placed. If it is necessary
to move the blocks at this
when they are very weak,
should be carefully lifted
carefully placed again. If the blocks
cannot be put inside
a shelter, cover them with heavy paper or plastic.
bags carefully opened and separated make excellent coverings).
is a shortage of storage space, the blocks can be
five rows high after three or four hours of drying
-- if they are very carefully handled.
The next day, the first operation is to move
the blocks to
for another day's production.
After the overnight drying, the blocks
should still be protected
weather because they must still cure slowly
or five more days. Soaking will harm
stage. Sunshine will make them cure too
their strength. In very hot climates
moist during this period. In any
climate they should
prevented from curing too fast. For the
first four days
should be sprinkled lightly with water twice a day.
cover is useful to maintain moisture in the pile.
used, double the curing time. The
blocks can be restacked
high on edge for the next curing period of 10
days. The blocks must not be
stacked solidly; there should be
of about an inch between blocks to let them cure properly.
stacking arrangement is three blocks side by
an inch space between them crossed with three blocks
alternating the direction of each layer (See Fig. 21).
In carrying out the curing process, try to
be moving the blocks
the construction site.
Never underestimate the importance of
Variations of Blocks, Floor Tiles The
CINVA-Ram box, when
without any inserts, produces a solid block 11-1/2" x
5-1/2" x 3-1/2" (9cm x 14cm x 29cm).
Inserts for the box,
included with the CINVA-Ram will change the size or
Frog A wooden "frog" (see Fig. 22)
in the box to produce a block
partially hollow core. The
of this block is that it
four-fifths the mixture
used in a
regular block -- reducing
and labor. These blocks
ideal for designing patterns
using blocks laid on
edge. The "frog" must
be kept clean.
Some soils will stick to the wooden
mold. A quick wipe with a
Blocks can be made with hollow cores
the whole length of the
block, but this takes a little more
time. The proper molds for these
have to be made (see Fig. 23);
not come with the press.
blocks can be used where metal
reinforcing rods are to be run through
With a little experience, operators
become proficient in making
Floor Tiles Tiles produced with the
Block Press make inexpensive,
attractive and durable flooring.
insert is a wooden
with a metal face (see Fig.24).
wearing surface on the tile is
a cement mixture.
(1) Screen the sand for this mixture as
finely as possible:
the finer the sand, the smoother the tile face will be.
Mix two parts sand with one part cement.
can be added to produce different colored tiles.
(3) Mix water with the sand
cement mix, as in paragraphs 37-39.
(4) Place the tile-making insert
in the box.
(5) Spread the cement mixture
over the insert to a depth
of one-quarter to
three-eights of an inch (6mm - 10mm).
(6) Add the soil-cement mixture
to this without completely
filling the box. The two
mixtures should be equally
The tile is then pressed and ejected in the same way as
the blocks. (See paragraphs 45
A pallet is helpful in carrying the newly
pressed tiles. The
which are thinner than the blocks, are more easily damaged
handling. Cured or partly cured blocks
can be used as pallets.
are turned over when removed from the machine and cured
up. They can be carried on the insert
to the curing spot
pallets are not used, and then inverted when placed down; but
operation is a little awkward and slows the tile making.
It is extremely important that the tiles
rest on a flat surface
first day of curing. A bowed surface
will make the
to the bow and the tile will either cure in a warped
A different method of facing is to place a
dry mixture of cement,
coloring into the box and then add a soil-cement mixture
slightly wetter than usual. This saves
the time it
make a wet mixture. It also spreads out
easier on the
The tile facing may stick to the
insert. Rust on the metal face
this. If nothing else stops the
sticking, put a
plastic or a piece of heavy paper (one ply of paper
bag will do) cut or torn to the size of the insert into
before filling. The plastic or paper
can be peeled off the
the pressed tile. One paper will last
for about twenty
Curing and Stacking Tiles are cured in the
same way as the
blocks, but they are stacked only two
high, with the faces together.
Other inserts provided with the CINVA-Ram
Block Press can be used
I-shaped blocks, blocks for utility conduction, and lintel
placing door supports).
Testing the Blocks The strength of the cured
blocks should be
tested. Most countries have a
university or building products
laboratory which can test the blocks.
Mortar The mortar joints between CINVA-Ram
blocks and tiles
1/2" (1cm) thick. Since the blocks
are 11-1/2" x
5-1/2" x 3-1/2" (9cm x 14cm x 29cm) the building unit is
x 4" (10cm x 15cm x 30cm). In flooring,
the 11-1/2" x
5-1/2" (14cm x 29cm) tiles plus the half inch (1cm) mortar
make a unit of 12" x 6" (15cm x 30cm).
The foundation for the blocks must be
firm. Use a cement-sand
for the first two layers to allow waterproofing.
The mortar recommended for the rest of the
building is one part
two parts lime and nine parts of the same soil used to
blocks. Lime is used because it forms a
since it sets more slowly than cement, it is less
crack. The mortar should be a moist
flow as freely as cement-sand mortar.
Surface Coating Let the mortar dry for about
a week. Then,
narrow brush, paint all the joints with a thin cement
which can be brushed into any fine cracks.
Stir the cement
frequently. Where large cracks develop
they should be
out to hold a packing of soil-cement mortar.
crack. Press the mortar in and
smooth it off.
The blocks alone have an attractive finish
but they can also be
the following way: after a day, paint all the exterior
with a cement wash of about rich milk consistency.
shade, keeping the cement wash well stirred.
recommended. The coats should be thin
to keep from
building up a crust of cement.
Allow a day between each coat.
A lime wash can be applied to make the
usually needs to be done again every year.
A silicone base wash (clear in appearance)
is an excellent
repellent for very rainy areas. In
has waterproofed blocks which were not coated with
wash. In areas of freezing weather,
precede the use of CINVA-Ram blocks.
Using Low Cost CINVA-Ram Earth Blocks for
Climates, by Chris Ahrens, U.S. Office of Economic
Opportunity, Arlington, Virginia, December 1970.
Handbook, by John R. Hansen, volunteer in American
Service Committee Summer Project, July 1963, Patzicia,
Home Construction: A Field and Library Compilation
with an Annotated Bibliography, by Lyle A.
Dunla and Bob M. Gallaway, Texas Transportation
Institute, A. & M. College of Texas, Bulletin No. 18, March
Homes, Ideas and Methods Exchange No. 22, U.S.
and Home Finance Agency, 3rd printing, revised
VII. OTHER MACHINES FOR MAKING BLOCKS FROM STABILIZED EARTH
Landcrete, manufactured by Messrs.
Africa) Lts., Johannesburg, and Trans-Atlas Ltd.,
St., Dublin 2, Ireland. A well-designed
press, sturdily constructed and simple to operate.
Winget, manufactured by Messrs. Winget Ltd.,
hydraulic press powered by a gasoline engine.
blocks produced is helped by high operating pressures,
production rate is the same as that of a hand-operated
Ellson Blockmaster, manufactured by Ellson
Johannesburg, South Africa. The machine
uses a toggle
lever system giving a constant length stroke which
standardizes the thickness of the blocks.
If you need
more information on the material in this manual or on other
matters, VITA (Volunteers in Technical Assistance) can send
you. If you have specific questions,
VITA can put you in contact
with an expert
who can answer them. VITA is an
scientists, engineers, technicians and businessmen who
their spare time to consult on questions from persons in
areas. Simply send your request to:
1815 North Lynn Street, Suite 200
Arlington, Virginia 22209 USA
STRUCTURAL CHARACTERISTICS OF SOIL-CEMENT BUILDING BLOCKS
(Reference: U.S. National Bureau of Standards - Building
Structures Report BMS 78).
Note: The pressurized blocks tested by The National Bureau
of Standards were
made using a
laboratory machine press which produced a block of similar quality
to the CINVA-RAM
block. Mix: Soil, 50% sand, 50% silt and clay; cement 8%.
General - A high-grade block is superior in many respects to
a common burned
brick and other
usual masonry materials. Even the
lowest density CINVA-Ram
press block has
structural qualities more than sufficient for one and two-storey
houses and other
Compressive Strength - Blocks withstood pressures up to 800
pounds per square
When you consider that the load at the foundation
line of a one-storey
house is only about
30 pounds per square inch, there is a factor of safety of
Adobe blocks seldom withstand more that 100
pounds per square inch.
Transverse Loading (wind load) - A wall made of pressurized
blocks withstood a
transverse load of
112 pounds per square foot. This will
withstand winds of
Weather Resistance - The pressurized block wall only leaked
through poor mortar
The unprotected block surface showed very
little erosion under severe
for low density blocks.
Impact and Concentrated Loading - The preformance of a
pressurized block wall
under those loadings
was superior to many types of masonry walls.
Resistance to Racking - This is the eccentric force on a
wall caused by
settling of part of
a foundation - also the type of force most often encountered
in a wall during an
earthquake. The test wall of
twice the force applied to a conventional frame wall and
over one-third more
than the force applied to a cement-block wall.
Fire Resistance - The pressurized soil-cement block is
Insulating Quality - The rate of heat passage through a
wall is about the
same as for a solid concrete wall of the same thickness.
CRBP Blocks compared with Adobe and Rammed Earth - A
pressurized block of soil-cement
such as is produced
by the CINVA-RAM Block Press is a comparatively
product. However, adobe and rammed
earth have been used for
building constructions throughout the world.
There are many
buildings in the
U.S. constructed of adobe and rammed earth over 100 years
old and still in
good condition. The CINVA-Ram press
block is far superior
in all respects to
either adobe or rammed earth as brought out in the Bureau
of Standards tests
as well as all other comparative tests of records.
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Volunteers in Technical Assistance (VITA) is a private,
international development organization.
It makes available
to individuals and groups in developing countries a
variety of information and technical resources aimed at
self-sufficiency--needs assessment and program development
support; by-mail and on-site consulting services;
VITA promotes the use of appropriate small-scale
especially in the area of renewable energy.
documentation center and worldwide roster of volunteer
experts enable it to respond to thousands of technical
inquiries each year.
It also publishes a quarterly newsletter
and a variety of technical manuals and bulletins.
VITA's documentation center is the storehouse for over
documents related almost exclusively to small- and
technologies in subjects from agriculture to wind
wealth of information has been gathered for almost 25 years
VITA has worked to answer inquiries for technical
from people in the developing world.
Many of the documents contained
in the Center were developed by VITA's network of technical
experts in response to specific inquiries; much of the
information is not available elsewhere.
For this reason, VITA
wishes to make this information available to the public.
For more information, contact VITA, P.O. Box 12438,
Virginia 22209, USA.
"Ode to a CINVA-Ram Block-making Machine"
I'll sing you the song of a CINVA:
A simple portable thing.
Earth pressing -- no
A fabulous blessing
When it comes to house construction.
Shovel earth into the mold box,
Then cover and give a big heave.
In compacting it's acting,
The pressure reacting:
Eject, and the brick is achieved.
I'll sing of a brand-new CINVA:
It calls us to start the day.
At dawning we're yawning
But the bricks, they are spawning,
And that has the biggest say!
So wherever you are in the wilds
Frustrated by lack of success,
A CINVA is soothing,
So useful it's proving,
Your project is bound to impress!
(British Branch of Service
Suihari, Dinajpur, EAST
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