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Making Building Blocks with
the CINVA-Ram Block Press
                                                           IN TECHNICAL
                                    1600 Wilson Boulevard, Suite 500
                                      Arlington, Virginia 22209 USA
                                 Tel:   703/276-1800 . Fax:  703/243-1865
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
                   IV.  MAKING BLOCKS AND TILES
                    V.  BUILDING
                    VI. REFERENCES
                        FROM STABILIZED EARTH
                        BUILDING BLOCKS
      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,

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          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
          **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
          **Depending on the quality of materials used, CINVA-Ram
            blocks can be superior to adobe and rammed
          **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.
      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
                                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
             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)
             8 Washers
      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
     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).

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          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
             (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).

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               (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"
                   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).
     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

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          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
     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).

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          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
               (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).

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               (3) Mix it thoroughly again, by
                   turning it over with a
     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.)

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          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
     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
     43.   Mounting the Machine   The CINVA-Ram Press (see Fig. 1) should

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          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

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                 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
             (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).

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             (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

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                 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).

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            (12) Depress the lever steadily to eject the block (see
                   Fig. 12).  If the block is cracked or deformed, it

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                   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).

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                    (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.)

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            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

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            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).

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               (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.)

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            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

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            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

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            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
       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
       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
               (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
       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
       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.
       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.
       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,
            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
            Earth for Homes, Ideas and Methods Exchange No. 22, U.S.
            Housing and Home Finance Agency, 3rd printing, revised
            September 1963.
       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
       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:
                      1815 North Lynn Street, Suite 200
                        Arlington, Virginia 22209 USA
(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
                                        Suihari, Dinajpur, EAST PAKISTAN