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close this bookAppropriate Community Technology - A Training Manual (Peace Corps; 1982; 685 pages)
View the documentThe Farallones Institute Rural Center
View the documentCHP International, INC.
View the documentPreface
View the documentAcknowledgments
View the documentIntroduction
close this folderPhase I: Introduction to training
View the documentPhase I Calendar
View the documentSession 1. Sharing perceptions of appropriate technology: an ice breaker
View the documentSession 2. Defining expectations of the appropriate community technology training program
View the documentSession 3. Group resource assessment
View the documentSession 4. Appropriate educational and learning processes part 1: non-formal education (nfe) and international community development work
View the documentSession 4. Appropriate educational and learning processes part 2: adult learning theory and how it is used in this training program
View the documentSession 5. Development of facilitation skills criteria
View the documentSession 6. Cross-cultural awareness and communication
View the documentSession 7. Hollow square
View the documentSession 8. Health in a cross-cultural context
View the documentSession 9. Community resource investigation
View the documentSession 10. An exercise in problem solving: formulating a plan for well-being
View the documentSession 11. Communication and listening skills
View the documentSession 12. Construction of earthen block molds: a focus on group dynamics
View the documentSession 13. Construction of earthen blocks
View the documentSession 14. Global energy issues
View the documentSession 15. Introduction to the evaluation process
View the documentSession 16. Evaluation and integration of training themes
Open this folder and view contentsPhase II: Earthen construction and fuel-saving cookstoves
Open this folder and view contentsPhase III: Pedal/treadle power
Open this folder and view contentsPhase IV: Solar water heaters
Open this folder and view contentsPhase V: Solar agricultural dryers
Open this folder and view contentsPhase VI: Concluding the program: The energy fair
Open this folder and view contentsAppendices
 

Session 13. Construction of earthen blocks

Total time:

2 hours

Objectives:

* To compare various clay-sand mixes suitable for the construction of earthen blocks* To construct earthen blocks

Resources:

* Adobe News Inc., "Adobe Today Newsletters"
* Boutette and Evans, Lorena Stoves
* Long, J. 3., Adobe Construction
* Neubauer, L. W., Adobe Construction Methods, Manual 19

Materials:

* For the shake/feel/shine and ribbon tests: glass jar or bottle, water and soil sample.
* For block construction: hoe, shovel, machete, appropriate earthen mixtures, water, straw and molds

Procedures:

Step 1. (10 minutes)
Introduce the session objectives and outline the procedures.

Step 2. (10 minutes)
Encourage the participants to share any experience or knowledge they may already have of earthen tech nologies.

Trainer Notes

During the discussion of the various types of earthen construction, mention the following applications:

* Wattle and daub
* Rammed earth
* Cob method
* Ferromud
* Earthen blocks
* Bamboomud
* Compressed blocks

Step 3. (10 minutes)
Describe the type of earthen blocks that will be made in today's session.

Trainer Notes

During your introduction, mention the following information:

* The utilization of mud blocks is often an appropriate substitute when access to manufactured construction material is limited and costs are high.

* Earthen blocks have many advantages: they are low-cost, durable and strong enough to be used as structural materials in a wide range of applications.

* Adobe buildings are fire-resistant, sanitary, dry and (due to the thermal properties of adobe) help equalize both hot and cold temperature extremes. Consequently, they are well-suited for use with passive solar heating designs.

* In addition, earthen construction is often an indigenous technology with which people may already be familiar.

* Earthen blocks are rectangular, shaped in molds, dried in the sun and then used in construction with mud or cement mortar.

* Bricks are made by mixing clay soil (28 - 48X clay) and water and then pouring the mixture into wood frame molds.

* Molds are generally 10cm x 30cm x 45cm (4" x 12" x 18"), having a volume of 16 liters (1/2 cubic foot) and weighing 23 kilograms (50 pounds).

* Blocks are left to dry three weeks, then turned on edge and left up to two weeks to cure.

Step 4. (15 minutes)
Have participants practice the shake/feel/shine/ thread and ribbon tests. Encourage a discussion of their findings and observations.

Trainer Notes

You can provide a focus for this discussion by asking:

How can this knowledge about soil composition be applied when making earthen blocks?

The participants should understand that these tests are to determine the relative amounts of sand and clay in the soil and to become familiar with the different soil types. A reference to these tests can be found in Lorena Stoves, pp. 42-44.

Mention the following information during the discussion:

* Clay is the glue that binds the sand particles together.

* Because sand is rigid and doesn't shrink during drying like clay, a mixture of clay and sand is less likely to crack.

* It is not only the amount of clay in the mixture but the type that affects cracking. Some clay types (Kaolin, for example) have a much lower expanding and shrinking quality.

Step 5. (10 minutes)
Have the participants assemble the construction materials.

Step 6. (5 minutes)
Ask the participants to form construction groups.

Step 7. (45 minutes)
Instruct the group to begin working and make earthen - blocks using the following procedure:

* Sift the soil and sand through a 3mm to 5mm (1/8" to 3/16") mesh screen.
* Dig a shallow pit to use as a mixing basin.
* Mix soil, sand and water to stiff mud consistency by puddling.

Trainer Notes

Explain here that the blocks should be of varying proportions of soil/sand and some should contain different admixtures such as chopped straw. These different proportions will produce varying results that can be evaluated by the participants as the blocks dry.

* Place a small amount of sand on the ground so blocks won't stick.

* Place the mold over the sand, making sure to wash the inside of the mold after each use.

* Fill the mold, ramming the mixture into all of the corners of the form, leveling the top and noting the soil/sand proportions on the surface of the block.

* Quickly withdraw the mold.

* Repeat the process until at least five blocks have been formed.

Trainer Notes

Circulate throughout the construction groups and offer assistance as needed.

Step 8. (5 minutes)
Reconvene the group and explain that the blocks should be turned on edge to allow for uniform drying in 2 or 3 days.

Trainer Notes

Encourage the groups to return periodically to examine the way in which the blocks are drying. Explain that ideally the blocks will dry completely in about two weeks.

Step 9. (10 minutes)
Have the participants clean up the work area and the tools.

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