Making Building Blocks with
the CINVA-Ram Block Press
VITA
VOLUNTEERS
IN TECHNICAL
ASSISTANCE
VITA
1600 Wilson Boulevard, Suite
500
Arlington, Virginia 22209 USA
Tel:
703/276-1800 . Fax:
703/243-1865
Internet: pr-info@vita.org
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.
VITA, Inc.
First printing
1966
Revised
January 1972
Minor revision
May 1975
Reprinting
February 1977
Making Building Blocks with
the CINVA-Ram Block Press
Table of Contents
I. INTRODUCTION
II. EQUIPMENT
III. TESTING SUITABILITY OF SOIL
IV. MAKING BLOCKS AND TILES
V. BUILDING
VI. REFERENCES
VII. OTHER MACHINES FOR MAKING BLOCKS
FROM STABILIZED EARTH
VIII. STRUCTURAL
CHARACTERISTICS OF SOIL-CEMENT
BUILDING BLOCKS
I. INTRODUCTION
1.
Purpose
This manual combines the experience of four men who
used the
CINVA-Ram Block Press and figured out answers, bit
by bit, to
the inevitable problems of detail as they came up
day after
day. That was the hard way to learn how
to use
the press;
this handbook is intended to make it easier.
2.
The Press
The CINVA-Ram Block Press is a simple, low-cost
portable
machine for making building blocks and tiles from
common soil
(see Fig. 1). The press, made entirely
of steel,
mbb1x1.gif (600x600)
has a mold
box in which a hand-operated piston compresses
a slightly
moistened mixture of soil and cement or lime.
(An
equipment list is on page 3.)
The press
was developed as a tool for small individual
or mutual
self-help programs. It was designed by
Raul
Ramirez, an
engineer, at the Inter-American Housing
Center
(CINVA) of the Organization of American States
in Bogota,
Colombia.
3.
Advantages
CINVA-Ram blocks and tiles have many
advantages
over other building materials.
**They are
easier to make than concrete blocks:
they can
be removed immediately from the press
and
stacked for curing without the use of a
pallet.
**The cost
of building material is greatly reduced,
since
most of the raw material comes from your
own land.
**Transportation costs are avoided since the machine
is
portable and the blocks are made near the construction
site.
**Depending
on the quality of materials used, CINVA-Ram
blocks
can be superior to adobe and rammed
earth.
**The
blocks are easily handled.
**The
blocks need no baking, since the curing process
is
completely natural .
**The press
makes variations of the block adapted to
the
various phases of construction.
4.
Note to the Field Worker
When teaching people how to use
the
CINVA-Ram Block Press, make your instructions as simple
and clear as possible.
Do not quote from this manual, but
master each
phase of the operation so that you can teach it
in your own
words. Encourage the workers to take
satisfaction
from the
completion of each step, every one of which is a
move toward
the final goal.
5.
Soil testing, block production and the use
of the blocks are
all
important, but they are less important than the will of
the
families to help themselves in building a home.
This may
well need
to be awakened and supported by your words of
encouragement and inspiration.
6.
Try to make at least one person in the group
familiar with
the whole
operation so that the local community will possess
the skill
to carry on the work alone.
II. EQUIPMENT
7.
CINVA-Ram Block Press
Weight:
140 lbs. (63 kilos)
Height
and base width:
10" x 16" x 26" (24 x 37 x 64cm)
Application force of lever:
80 lbs. (36 kilos)
Bearing
Strength (Fully cured blocks)
200-500 psi (14-35 kg/[cm.sup.2])
Size of
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)
Size of
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)
Average
number of blocks or tiles
300-500
can be
made by two people per day:
Average
number of blocks needed 2500
for a
two-room house:
Average
number of blocks per 150
100 lbs. of cement:
Inserts: Four different molds
for producing
different kinds of blocks and tiles.
Cost
in United States: $175 FOB
Warehouse Tallmadge, Ohio
AVAILABLE FROM:
Bellow's Valvair International
200 W. Exchange St.
Akron, Ohio 44309
216-762-0471
Metalibec Ltda.
Apartado Aereo 233-NAL
157
Bucaramanga, Colombia
South America
Materiel Industriel et Menager Japy
6 rue de Marignana
Paris [8.sup.e] FRANCE
Frazer Engineering Company
116 Tuam Street
Christchurch, NEW ZEALAND
8.
Other Equipment Needed
1
Wide-mouth glass jar
1/4" to 3/8" (6mm to 10mm) mesh wire screen
Box,
inside dimensions: 24" x 1-1/2" x 1-1/2"
(60cm x
4cm x 4cm)
Fine
sieve
Suitable
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
Bottomed
measuring box
Shovel
Sprinkling can
Mounting
board at least 9' long, 8" wide and 2" thick
(2.50M x
20cm x 5 cm)
4 Bolts
at least 1/2" (1.5cm) diameter and 3" (8cm)
long
8
Washers
III. TESTING FOR THE SUITABILITY OF THE SOIL
9.
Need for Testing
Making blocks from stabilized earth is a
simple
process, but it will not be successful unless the soil
is properly
tested. It would be a serious mistake
to treat
this step
lightly. Scarce money and labor could
be wasted
for an
unsatisfactory result.
10.
Soil is a variable and complex building
material. Every sample
is
different from every other sample. But building blocks can
be made
successfully from a wide variety of soils.
11.
Purpose of the Tests
The tests described here will tell us:
(1)
How much sand and how much clay is in the soil to
be
used (Particle Determination Test and Compaction Test,
paragraphs 16 and 17).
(2)
How much cement or lime should be added (Box Test,
paragraph 18).
12.
Clay
It is mainly the clay content which gives the mixture
cohesion.
13.
Stabilizer One of the important functions of
the
stabilizer
is to reduce the change in the volume of the clay, which
swells as
it takes up water and then shrinks as it dries.
Portland
cement is the best stabilizer, but slaked lime can
also be
used. In some areas, lime is readily
available and
cheaper
than cement. With lime, a higher
percentage is needed
for
stabilizing than with cement. Lime does
not work well with
all soils,
however; careful experimentation is therefore
necessary. Lime can often be
used with excellent results in
combination
with cement. This cuts down on the
amount of
cement
needed. But it is important to remember
that lime
dries more
slowly and therefore needs a longer curing period.
Tests have
shown good results with 1/3 cement - 2/3 lime mixture.
14.
Organic impurities
Organic material is found in the
surface
layer of most soils. Soil used for
block making should be
reasonably
free of organic matter, which hinders the setting
and
hardening of the cement and results in weak blocks.
Therefore,
the topsoil
should not be used unless most organic
material is
removed.
15.
Mixture
A wide range of soils is suitable for making blocks.
We want:
(1) a good proportion of sand to form the body of
the block;
and (2) a certain amount of cohesive or plastic
fine
particles (clay) to bind the sand particles together.
Good blocks can be made with even a
small amount of clay, but
there must
always be some clay. If a small amount
of stabilizer
is enough,
save on cost reducing the amount used.
Learn to
find sand
by testing, because soils commonly considered clay
may contain
a good percentage of sand.
Simplified Field
Tests
16.
Particle Determination Test This test
analyzes the soil to
find the
ratio of sand to clay and/or silt:
(1) Pass
the soil through a 1/4" (6mm) screen
(2)
Pour into a wide-mouth jar enough soil to fill the
jar half full.
(3)
Fill the jar with water and cover it.
(4)
Add 2 teaspoons of salt to help the clay/silt
particles settle faster.
(5)
Shake the jar vigorously for 2 minutes.
(6)
Set the jar on a level spot.
The soil
should settle in about half an hour.
The sand
will settle
quickly to the bottom. The clay/silt
particles
will settle
last. Measure the layers to determine
the ratio
of sand and
clay/silt (see Fig. 2).
mbb2x6.gif (600x600)
Use soil
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.
Record the
percentages
of sand and clay/silt in the soil used.
This
will help
in deciding which soil makes the best blocks.
17.
Compaction Test. This test
indicates the packing quality of
the earth,
which depends on the percentage of clay in the
sample.
(1) Take
a handful of dry, screened earth and moisten it
until it is damp enough to form a ball when squeezed
in
the hand, but not so damp that it will leave more
than
a slight trace of water on the palm.
(2) Drop
the ball from a height of about three feet
onto
hard ground. If the ball breaks into a
few smaller
pieces, the packing quality is good to fair.
If it
disintegrates, the quality is poor.
18.
Box Test The box test is a guide to the
proper soil-cement
ratio.
It measures the shrinkage of soil which contains no
stabilizer. The box should have
these inside measurements:
24" x
1-1/2" x 1-1/2" (4cm x 4cm x 60 cm) (see Fig. 3).
mbb3x7.gif (486x486)
(1)
Oil or grease the
inside surfaces of
the box thoroughly.
(2)
Pack the box well
with moist soil
(previously passed
through a 1/4" -3/8"
(6mm-10mm)
mesh screen).
The
soil should be
moistened to pack
well, but it should
not be muddy.
(3)
Tamp, especially at the corners.
(4)
Smooth off the surface with a stick.
(5)
Place the box in the sun for three days or in
the shade for seven days. It
should be protected
from rain.
19.
Measure the contraction (shrinkage) by
pushing the dried
sample to
one end of the box.
Shrinkage
Cement to Soil Ratio
Not over
1/2" (15mm) 1 part
to 18 parts
Between
1/2" and 1" (15mm - 30mm)
1 part to 16 parts
Between 1" and 1-1/2"
(30mm - 45mm) 1 part to 14 parts
Between
1-1/2" and 2" (45mm-60mm)
1 part to 12 parts
When lime
is used instead of cement, use double the amount.
Do not use
the soil if it has many cracks (not just three or
four); if
it has arched up out of the box; or if it has shrunk
more than
2" (60mm).
IV. MAKING BLOCKS
AND TILES
20.
The proportion of cement and/or lime needed
to stabilize the
mixture has
been determined by the box test.
21.
The number of blocks and tiles needed should
be calculated
from the
plans for walls and floors. Three
blocks (laid
flat) give
one square foot of wall (33/[m.sup.2]); two tiles give
one square-foot of flooring (22/[m.sup.2].
22.
You may not be present during the
block-making. Go through
each step
with the group doing the work until you are satisfied
that the
steps are clearly understood. Be
generous
with encouragement.
Organize the physical layout of the
mbb4x9.gif (600x600)
steps of
the operation as efficiently as possible.
The
movement of
the operation should be a flow of work, with
the fewest
possible number of footsteps, toward the final
stacking
near the construction site in the following order:
(1)
Digging and screening the soil
(2)
Preparing the mixture
(3)
Pressing the blocks
(4)
Curing and stacking the blocks
23.
Circumstances will not always permit a
direct flow. Therefore,
some
forethought is needed to set up the best operation for
your
situation.
Digging and
Screening
24.
Digging At the selected excavation spot,
strip the surface
soil of all
vegetation. If the vegetation is
carefully removed
and stored,
it can be used later for planting around the completed
house or
for replanting the soil supply pit.
25.
The amount of topsoil which must be removed
to avoid getting
organic
matter into the mixture varies in different locations.
It may go
to a surprising depth of several feet, or it may not
be
necessary to remove any at all.
Normally, six inches
to a foot
(15cm-30cm) should be enough.
26.
Generally the soil gets sandier as the hole
gets deeper.
Sandy soil
with a low proportion of clay makes the best blocks.
Sometimes a
layer of clay subsoil will be followed by very
sandy soil,
and combining the two in the screening or mixing
steps will
produce a stronger block.
27.
If, as the hole gets deeper, the pit
produces soil which is
not good
for block-making, there is no choice but to enlarge
the
excavation area.
28.
The person supervising the work will
probably not be present
during the
digging. Therefore he should give a
simple
explanation
of soil composition at the start of digging so
that any
pronounced change in sand or clay content will be
noticed.
29.
In Case of Rain In a period of alternating
showers and sunshine,
provision
should be made to cover the pit (for
example,
with roofing sheets), so that work can continue
immediately
after the showers. Where surface water
can run
into the
pit, put up a small retaining barrier of soil.
The
pile of
screened soil should, of course, be protected by a
covering
which will shed most of the rain.
30.
Screening The soil should be
screened
through 1/4" or 3/8"
(6mm or
10mm) wire mesh (see
Fig. 5).
mbb5x10.gif (600x600)
The screen
should be mounted at
a level
where it can be shaken
by hand
without back-bending; for
example, by
suspending it from
two trees
or posts (see Fig. 5).
The
screening operation is one
where women
and children can help
in
block-making.
31.
It is important to keep the CINVA-Ram
operating steadily.
It should
not be idle while soil is being dug and screened
32.
Experience is needed to know how large a
stockpile of
screened
earth is needed for different sized buildings.
It can be
estimated, since it will take up 1-1/2 to 1-2/3
times its
volume in the compacted blocks.
33.
Preparing the Mixture
The importance of thoroughness in
both cement
mixing and moisture mixing, two distinct steps
in
preparing the mixture, cannot be emphasized too strongly.
34.
Cement Mixing
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.
A flat
concrete slab or an area of compacted and stabilized
earth
serves equally well.
35.
Measuring boxes whose sizes can be
determined from the
tests in
paragraphs 16-19 can be very effective in making
sure that
the correct proportions of soil and cement are
mixed.
(1)
Set a large bottomless measuring box on the
mixing board.
(2)
Fill it with soil and level off the top.
(3)
Lift the box, leaving a measured pile of soil
on
the board. The soil should be spread
out
over the mixing board as the box is lifted.
(4)
Use a smaller bottomed measuring box for a measured
amount of cement. The cement should
be emptied
evenly over the soil.
(5)
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.
36.
Do not use lumpy cement.
Pass it through a fine screen (window
screen or
finer); discard lumps which will not break up easily
with the
fingers and pass through the screen.
37.
Moisture Mixing
(1)
Spread out the thoroughly
mixed soil-cement mixture
on
the mixing board.
(2)
Add water with a sprinkling
can without making puddles
(see Fig. 6).
mbb6x11.gif (486x486)
(3)
Mix it thoroughly again, by
turning it over with a
shovel.
38.
Keep the amount of water less than what
seems to be enough.
More water
can be mixed in, but much time can be lost in
getting rid
of excess water.
39.
With a little experimentation it will be
possible to calculate
the amount
of water for each mix. This will save
the
time it
takes to make small additions of water and repeat
the mixing
process. It is important to remember
that the
mixture
will look as though it is not moist enough.
40.
Testing for the Correct Amount
of
Moisture. The correct amount of
moisture is
quickly learned through
experience. To test it, squeeze
a
handful of
the mixture. (See Fig. 7.)
mbb7x12.gif (353x353)
If it is
moist enough it will keep the
shape it is
squeezed into. If dropped
onto a hard
surface from shoulder
height, it
should break into small
fragments. The mixture is too
moist
if water is
squeezed out of the top
of the
machine box when a block is
pressed.
41.
The mixture should be used within one hour
after water
has been
added.
42.
Pressing the Blocks
The first point that must be driven home
to all
operators of the CINVA-Ram is that they should not put
too much
strain on the machine when they press a block.
Never
should two
men press on the handle to bring it down in making
a
block. Nor should anyone jump on the
handle to force it
down with
repeated thrusts of his body. This
point cannot be
emphasized too strongly because such a strain
will damage the
machine.
43.
Mounting the Machine
The CINVA-Ram Press (see Fig. 1) should
mbb1x1.gif (600x600)
be mounted
on a board at least 9' long, 8" wide and 2" thick
(2.5M x
20cm x 5cm). A narrower board will let
the press
tip sideways; a shorter board will lift up at the
ends,
making it hard to get the right amount of pressure on
the block;
a thinner board will split under pressure.
44.
The bolts should be at least one-half inch
in diameter and
three
inches long (1.5cm x 8cm). It is good
to
put washers
under the heads of the bolts on the underside of
the board,
especially on the end of the press with the lower
rollers, since this end receives the
greatest pressure. The
washers
help to keep the bolt head from pulling through the
board.
If the heads do start to pull through,
install larger
washers
immediately; the great strain put on a loosely mounted
press can
easily throw it out of adjustment and eventually
break it.
45.
Pressing.
(1) Open
the cover.
(2) Make
sure the piston is all
the
way down. If it is part
way
up it will not be possible
to
get the correct amount
of
mixture into the box.
(3) Dump
the proper amount of
soil-cement mixture into the
box
(see Fig. 8). The supervisor
mbb8x13.gif (437x437)
should determine the
correct amount of mixture for
each
block - a measuring box
can
be used to make sure that
the
same amount is used each
time.
Uniformity in loading
is
absolutely necessary for
producing uniform blocks.
(4) Fill
the corners of the box to
the
top so that the corners of
the
finished block will be well
pressed.
(5)
Press a bit in the corners with
your
fingers.
(6)
Replace the cover.
(7) Move
the lever to a vertical
position, letting the lower
rollers fall into place
(see
Fig. 9).
mbb9x13.gif (437x437)
(8)
Disengage the lever latch.
(9) Move
the lever to a horizontal
position on the side opposite
the
lower rollers.(compression
cycle) (see Fig. 10). If the
mbb10x13.gif (437x437)
right amount of mixture is used,
one
man of average weight should
be
able to move the lever down
alone with only two or three
pushes.
The lever must be
lowered completely; otherwise the block will be too
thick, wasting material and producing a block which
may
be too thick to use.
(10) Move
the lever to a vertical position, engage the
lever latch and return the lever to its rest position
on
the lower rollers.
(11) Open
the cover (see Fig. 11).
mbb11x14.gif (437x437)
(12)
Depress the lever steadily to eject the block (see
Fig. 12). If the block is
cracked or deformed, it
mbb12x14.gif (437x437)
should not be used. Read the
instructions in paragraphs
52-61, Adjustments.
(13) If
the blocks are lifted from the machine and carried
properly and carefully, and if the mixture is correct
and
the machine is in good adjustment, the blocks
will
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).
mbb13x15.gif (437x437)
(b) To set the brick down, tip it into place
on its side.
46.
Try to have at least two men operating the
machine, because
it is
very time-consuming to have one man moving from one side
of the
machine to the other to press and eject.
But it can be
done by
one man if only one is available. Four
persons make
an ideal
team for pressing: one filling, one pressing, one
ejecting,
and one removing. A team of four can
easily produce
two
blocks a minute if the mixture is prepared and
close by.
47.
Sticking Some soils stick more than
others. An occasional
cleaning
of the corners of the press box with a metal scraper
may be
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.
48.
Rotating Jobs On a job where there is enough
labor to have
all the
steps -- digging, screening, mixing, loading, pressing,
ejecting,
and carrying -- going on at the same time, it is
fair and
good for morale to rotate the jobs every hour or so.
Maintenance
and Repairs
49.
Lubrication All moving parts and wearing
parts (rollers,
pins,
pressure plate, guide plates, piston cylinder, bearings
and
supports of axles) should be well lubricated every
four to
eight hours with heavy oil or grease to insure smooth
operation
and cut down on wear.
50.
Pins The pins which secure the pivot shafts,
compression
yoke and
rollers should be replaced when broken by the
largest
nails available, because they will last longer than
the
average cotter pin. If C-ring
replacements are not
available, broken C-rings can be replaced by wrapping a
piece of
wire in the groove.
51.
Clean Surfaces The inside of the box and the
under surface
of the cover-must be kept clean.
52.
Adjustments The CINVA-Ram press should not
be tampered with
unnecessarily, but the following suggestions
may help
if the press produces faulty blocks.
53.
Breaks and Cracks Breaks and cracks are
caused by loose or
incorrectly adjusted guideplates.
54.
Side Breaks (See Fig. 14.)
mbb14x16.gif (353x353)
Move the
lower adjusting bolts
(G and H)
sideways toward the
high side
of the break (see Fig. 1).
If more
adjustment is needed, move
the upper
adjusting bolts (E and F)
toward
the low side of the break.
This can
sometimes be done simply
by
hammering the bolt sideways (with
a piece of wood, so that the threads
will not
be damaged) rather than by
loosening
and tightening the nuts.
After the
bolts are hammered over,
tighten
the nuts.
55.
End Breaks (See Fig. 15.) Move
mbb15x16.gif (353x353)
the guide
plate opposite the end
where the
break occurs inward by
turning
lower adjusting bolt G or
H,
depending on the guide plate to
be moved
(See Fig. 1). NOTE: Moving
one end
of a guide plate in one direction forces the other
end of
the same plate in the opposite direction.
If this
loosens
the piston much at either the top or the bottom of
the guide
plate, the other end of the plate must be moved
inward. The free play should be
corrected because it will
cause the
piston to crack the blocks by compressing them
in one
direction in the compression cycle (with the upper
saddle as
the pivot point) and in another direction in the
ejection
cycle (with the lower rollers as the pivot point).
Also, the
guide plates must be tight enough against the
piston to
keep it from jerking and jumping upward at the
end of the
ejection cycle.
56.
If end cracking is not stopped by tightening
the plates
against
the piston, it may be necessary to tilt the guide
plates
and the piston, so that the pressure plate will be
higher at
the end which is cracking. This is done
by
moving
the tops of both guide plates toward the cracked end.
57.
Corner Breaks A corner break
is caused
by a combination of
a side
break and an end break
(see Fig.
16).
mbb16x17.gif (317x317)
(1)
Fix the side crack by moving
the bolts sideways, as
in
paragraph 54 (usually it
is
only necessary to move the
bottom bolt on the end with the crack toward the
side where the crack occurs).
(2)
Fix the end crack by moving the lower adjusting
bolt opposite the cracking end inward against
the piston, as in paragraph 55.
58.
Tapering Tapering is caused by incorrectly
adjusted guide plates.
59.
Side Taper (See Fig. 17.)
mbb17x17.gif (317x317)
First
move the guide plate
on the
thicker side outward; then
move the
other guide plate inward
(see Fig.
1). The guide plates
should be
kept parallel to each
other. Move both the tops and
bottoms
of both guide plates the
same
distance.
60.
End Taper (See Fig. 18) Move the
mbb18x18.gif (317x317)
tops of both
guide plates toward
the thin
end. Move the bottoms of
both
guide plates toward the thick
end. (See
Fig. 1) The tops should
be moved
as far in one direction as
the
bottoms are in the other.
61.
Corner Taper (See Fig. 19) A
mbb19x18.gif (285x285)
corner
taper (one corner thinner
than the
rest) is caused by a
combination of a side taper and an
end
taper. First, fix the side taper
by moving
the guide plates as in paragraph
59.
Second, fix the end taper
by moving
the guide plates as in paragraph
60.
62.
Curing and Stacking the Blocks The curing of
the blocks is
another
important step which must be taken with care.
To become
careless
at this point could ruin all the careful work that has
gone
before.
63.
The moisture in the blocks must
come out
slowly and evenly.
64.
The blocks should be laid on
flat,
unwarped, clean planks
wide
enough to support the full
width of
the blocks (See Fig. 20)
mbb20x18.gif (393x393)
If such
boards are not available,
the
blocks should be placed on
smooth
ground covered with paper
or leaves
so that they will not
be in
direct contact with the
earth
65.
The blocks should not be pushed
into
another position after
being
placed. If it is necessary
to move the blocks at this
point
when they are very weak,
they
should be carefully lifted
and
carefully placed again. If the blocks
cannot be put inside
or under
a shelter, cover them with heavy paper or plastic.
(Paper
cement
bags carefully opened and separated make excellent coverings).
If there
is a shortage of storage space, the blocks can be
stacked
five rows high after three or four hours of drying
-- if they are very carefully handled.
66.
The next day, the first operation is to move
the blocks to
make room
for another day's production.
67.
After the overnight drying, the blocks
should still be protected
from the
weather because they must still cure slowly
for four
or five more days. Soaking will harm
the blocks
at this
stage. Sunshine will make them cure too
quickly,
reducing
their strength. In very hot climates
blocks should
be kept
moist during this period. In any
climate they should
be
prevented from curing too fast. For the
first four days
they
should be sprinkled lightly with water twice a day.
A
plastic
cover is useful to maintain moisture in the pile.
If
lime is
used, double the curing time. The
blocks can be restacked
ten rows
high on edge for the next curing period of 10
days. The blocks must not be
stacked solidly; there should be
a space
of about an inch between blocks to let them cure properly.
A good
stacking arrangement is three blocks side by
side with
an inch space between them crossed with three blocks
above --
alternating the direction of each layer (See Fig. 21).
mbb21x19.gif (353x353)
68.
In carrying out the curing process, try to
be moving the blocks
closer to
the construction site.
69.
Never underestimate the importance of
careful curing.
70.
Variations of Blocks, Floor Tiles The
CINVA-Ram box, when
used
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,
which are
included with the CINVA-Ram will change the size or
shape of
the blocks.
71.
Frog A wooden "frog" (see Fig. 22)
mbb22x20.gif (353x353)
is used
in the box to produce a block
with a
partially hollow core. The
advantage
of this block is that it
uses only
four-fifths the mixture
used in a
regular block -- reducing
both cost
and labor. These blocks
are also
ideal for designing patterns
in walls
using blocks laid on
edge. The "frog" must
be kept clean.
72.
Some soils will stick to the wooden
mold. A quick wipe with a
kerosene-dampened
rag will
overcome this.
73.
Blocks can be made with hollow cores
running
the whole length of the
block, but this takes a little more
time. The proper molds for these
blocks
have to be made (see Fig. 23);
mbb23x20.gif (317x317)
they do
not come with the press.
These
blocks can be used where metal
reinforcing rods are to be run through
the laid
blocks.
74.
With a little experience, operators
will
become proficient in making
these
blocks.
75.
Floor Tiles Tiles produced with the
CINVA-Ram
Block Press make inexpensive,
attractive and durable flooring.
The tile
insert is a wooden
block
with a metal face (see Fig.24).
mbb24x20.gif (317x317)
The
wearing surface on the tile is
made with
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.
(2)
Mix two parts sand with one part cement.
Mineral coloring
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
wet.
(7)
The tile is then pressed and ejected in the same way as
the blocks. (See paragraphs 45
and 46.
76.
A pallet is helpful in carrying the newly
pressed tiles. The
tiles,
which are thinner than the blocks, are more easily damaged
in
handling. Cured or partly cured blocks
can be used as pallets.
The tiles
are turned over when removed from the machine and cured
face
up. They can be carried on the insert
to the curing spot
if
pallets are not used, and then inverted when placed down; but
this
operation is a little awkward and slows the tile making.
77.
It is extremely important that the tiles
rest on a flat surface
for the
first day of curing. A bowed surface
will make the
tile sag
to the bow and the tile will either cure in a warped
shape or
crack.
78.
A different method of facing is to place a
dry mixture of cement,
sand and
coloring into the box and then add a soil-cement mixture
which is
slightly wetter than usual. This saves
the time it
takes to
make a wet mixture. It also spreads out
easier on the
insert.
79.
The tile facing may stick to the
insert. Rust on the metal face
can cause
this. If nothing else stops the
sticking, put a
sheet of
plastic or a piece of heavy paper (one ply of paper
cement
bag will do) cut or torn to the size of the insert into
box
before filling. The plastic or paper
can be peeled off the
face of
the pressed tile. One paper will last
for about twenty
tiles.
80.
Curing and Stacking Tiles are cured in the
same way as the
blocks, but they are stacked only two
high, with the faces together.
81.
Other inserts provided with the CINVA-Ram
Block Press can be used
to make
I-shaped blocks, blocks for utility conduction, and lintel
blocks (for
placing door supports).
82.
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.
V. BUILDING
83.
Mortar The mortar joints between CINVA-Ram
blocks and tiles
should be
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
12"
x 6"
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
joints,
make a unit of 12" x 6" (15cm x 30cm).
84.
The foundation for the blocks must be
firm. Use a cement-sand
mortar
for the first two layers to allow waterproofing.
85.
The mortar recommended for the rest of the
building is one part
cement,
two parts lime and nine parts of the same soil used to
make the
blocks. Lime is used because it forms a
more plastic
mortar;
since it sets more slowly than cement, it is less
likely to
crack. The mortar should be a moist
mixture which
does not
flow as freely as cement-sand mortar.
86.
Surface Coating Let the mortar dry for about
a week. Then,
using a
narrow brush, paint all the joints with a thin cement
wash
which can be brushed into any fine cracks.
Stir the cement
wash
frequently. Where large cracks develop
they should be
gouged
out to hold a packing of soil-cement mortar.
Wet the
crack. Press the mortar in and
smooth it off.
87.
The blocks alone have an attractive finish
but they can also be
coated in
the following way: after a day, paint all the exterior
walls
with a cement wash of about rich milk consistency.
Work
in the
shade, keeping the cement wash well stirred.
Three
coats are
recommended. The coats should be thin
to keep from
building up a crust of cement.
Allow a day between each coat.
88.
A lime wash can be applied to make the
building waterproof.
This
usually needs to be done again every year.
89.
A silicone base wash (clear in appearance)
is an excellent
water
repellent for very rainy areas. In
experiments this
solution
has waterproofed blocks which were not coated with
a cement
wash. In areas of freezing weather,
experimentation
should
precede the use of CINVA-Ram blocks.
VI. REFERENCES
90.
Using Low Cost CINVA-Ram Earth Blocks for
Construction in
Cold
Climates, by Chris Ahrens, U.S. Office of Economic
Opportunity, Arlington, Virginia, December 1970.
CINVA-Ram
Handbook, by John R. Hansen, volunteer in American
Friends
Service Committee Summer Project, July 1963, Patzicia,
Guatemala.
Earthen
Home Construction: A Field and Library Compilation
with an Annotated Bibliography, by Lyle A.
Wolfskill,
Wayne A.
Dunla and Bob M. Gallaway, Texas Transportation
Institute, A. & M. College of Texas, Bulletin No. 18, March
1962.
Earth for
Homes, Ideas and Methods Exchange No. 22, U.S.
Housing
and Home Finance Agency, 3rd printing, revised
September
1963.
VII. OTHER MACHINES FOR MAKING BLOCKS FROM STABILIZED EARTH
91.
Landcrete, manufactured by Messrs.
Landsborough Findlay
(South
Africa) Lts., Johannesburg, and Trans-Atlas Ltd.,
15 Duke
St., Dublin 2, Ireland. A well-designed
hand-operated
toggle
press, sturdily constructed and simple to operate.
92.
Winget, manufactured by Messrs. Winget Ltd.,
Rochester, England.
A
hydraulic press powered by a gasoline engine.
The quality
of the
blocks produced is helped by high operating pressures,
but the
production rate is the same as that of a hand-operated
machine.
93.
Ellson Blockmaster, manufactured by Ellson
Equipments (Pty).
Ltd.,
Johannesburg, South Africa. The machine
uses a toggle
switch
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
technical
matters, VITA (Volunteers in Technical Assistance) can send
it to
you. If you have specific questions,
VITA can put you in contact
with an expert
who can answer them. VITA is an
international
association of
scientists, engineers, technicians and businessmen who
volunteer
their spare time to consult on questions from persons in
developing
areas. Simply send your request to:
VITA
1815 North Lynn Street, Suite 200
Arlington, Virginia 22209 USA
VIII.
STRUCTURAL CHARACTERISTICS OF SOIL-CEMENT BUILDING BLOCKS
(Reference: U.S. National Bureau of Standards - Building
Materials and
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
small structures.
Compressive Strength - Blocks withstood pressures up to 800
pounds per square
inch.
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
over 20.
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
top hurricane
strength.
Weather Resistance - The pressurized block wall only leaked
through poor mortar
joints.
The unprotected block surface showed very
little erosion under severe
surface treatment
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
pressurized
blocks withstood
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
fireproof.
Insulating Quality - The rate of heat passage through a
pressurized block
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
new building
product. However, adobe and rammed
earth have been used for
centuries in
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.
ABOUT VITA
Volunteers in Technical Assistance (VITA) is a private,
nonprofit,
international development organization.
It makes available
to individuals and groups in developing countries a
variety of information and technical resources aimed at
fostering
self-sufficiency--needs assessment and program development
support; by-mail and on-site consulting services;
information
systems training.
VITA promotes the use of appropriate small-scale
technologies,
especially in the area of renewable energy.
VITA's extensive
documentation center and worldwide roster of volunteer
technical
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
40,000
documents related almost exclusively to small- and
medium-scale
technologies in subjects from agriculture to wind
power. This
wealth of information has been gathered for almost 25 years
as
VITA has worked to answer inquiries for technical
information
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,
Arlington,
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
messing!
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!
John Miles
International Voluntary
Service
(British Branch of Service
Civil
Internationale)
Suihari, Dinajpur, EAST
PAKISTAN
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