Problem Definition

Background

Las Malvinas is a community near Santo Domingo, the capital city of the Dominican Republic. There are more than 150 families who live in this semi-rural setting, situated next to the Isabella River. By a vote of hands, the community decided that the project they want to collaborate on the most is to add another classroom on to their school using alternative construction methods like papercrete and ecoladrillo.

Papercrete is similar to concrete blocks, but these blocks are made with recycled paper. Ecoladrillo uses wooden frames, plastic bottles, chicken wire, and concrete to make walls.

There is an abundance of both materials (bottles and recycled paper), and there is a need in the community for more space to hold their youngest students. So, we're going to work with the cheapest, most local materials to help Las Malvinas complete this project, while we students from Humboldt State are learning how to implement modes of sustainable construction.

en espanol: Las Malvinas es una comunidad cerca de Santo Domingo, en la República Dominicana. Hay más que 150 familias que se viven en esta escenario rural, al lado del Río Isabella. Por un voto de las manos, la comunidad decidio que el proyecto que se quieren más es que construir una aula para la escuela, usando modos alternativos de construcción como "papercrete" y "ecoladrillo."

"Papercrete" es similar a bloques de concreto, pero estos bloques son de papel reciclado. "Ecoladrillo" se usa botellas plásticas y concreto para hacer paredes.

Hay un abundancia de ambos materiales (botellas y papel reciclados), y necesitan más espacio en la escuela. Entonces, váminos a trabajar con las materiales más locales y baratos para ayudar esta comunidad cumplir este objetivo mientras estámos apriendo a implementar modos de construcción sostenable.

Criteria

Criteria and constrains are needed to determine the success of a solution. Criteria are weighted with 10 being most important and 0 being least important.
Criteria Constraint Weight
Safety The classroom meets or exceeds local building codes 10
Reproduction Costs The total cost of construction is less than the cost of traditional construction. 8
Appropriate Materials Building materials are local, alternatively resourced, and may be easily obtained by the community. 7
Aesthetics The classroom looks good with the existing school structure while having a unique appearance that draws positive attention to its alternative construction. 8
Ease of Use The classroom comfortably accommodates the most number of students possible for the given space, up to 35 students. 7
Community Interest Maximize community involvement to develop their interest in the project, as well as their skills and knowledge necessary to replicate the project later. 10
Research and Development Costs Spend no more than US$1000 5

Literature Review

Climate

The Dominican Republic is in a tropical climate zone, where rainfall varies seasonally but temperatures are relatively static, [1] ranging from 64 to 90 degrees Fahrenheit year round.[2] The rainy season begins in early summer and lasts through mid fall, with the the most powerful tropical storms occurring during August and September.[2] The average annual rainfall is 150cm[3], much of which falls on the northern side of the island. This results in cooler temperatures and higher humidity in comparison to the south.[4]

Earthen Flooring

Introduction

An earthen floor is made up of four basic layers. A layer of substrate dirt or sawdust that is laid down on top of a layer of fine gravel, which is then covered with a layer of clay or sand and sealed with a layer of hemp or linseed oil. The result is a porous, supple and durable floor which can be made for less than a dollar per square foot. (including labor).[5]Rammed earth is a style of earthen floor that uses tamping or ramming to compact and harden the layers. Specific ingredients and construction methods vary by location. The overarching idea is to add water and stabilizing agents like sand and straw to dirt, which is then compacted until hard. Once dry, seal it with an oxidizing oil like linseed or hemp oil. [6]

Methods

For a general rammed earth floor, the first step is to lay down a plastic moisture barrier sandwiched between two thin layers of sand, followed by 4 to 6 inches of compacted "road base mixture."

  • clay, sand, and various types of gravel (ratio unimportant)

It is important to tamp the floor and sprinkle it with water every additional few inches to ensure good and even compaction. The next step is to add a one inch layer of standard earth plaster mix.

  • 6 parts sand, 2 parts clay, 1 part finely chopped straw

The plaster should then be troweled smooth and allowed to dry. Once dry, the final step is to lay down four layers of linseed or hemp oil, allowing each layer to dry before applying the next. The last three coats of oil should be mixed with increasing ratios of citrus paint thinner. [7]

To get the right mix, experiment with a test area of at least 3x3 ft. The mix should be strong enough that it is not powdery when it dries, and it must contain enough fiber so that there are no cracks. Apply the mixture with a trowel in 1/2-3/4" layer. The material should come off cleanly and easily as you move the trowel across the sub-floor. If it sticks, there’s either too much clay or not enough moisture; if it won’t stick to the trowel, there’s either too much moisture or not enough clay. [8]

Homeowners in a wet climate should put down several inches of gravel to enhance drainage. This can be a three- to four- inch layer of clay, sand, and gravel or crushed stone, on top of which lays the half-inch layer of finer mix. If you pour this supportive layer in a damp state—and even add lime to the mixture—it will dry and harden more quickly. [8] A typical earthen floor might include a 2.5-inch base layer of 70% sand, 30% clay, with handfuls of long straw for tensile strength. Once it is dry, the final layer will be installed and smoothed with a trowel, composed of a similar sand to clay ratio, but mixed with very short chopped straw. [9]

Linseed Oil Coating

Increasing amounts of paint thinner in the linseed coatings allow deep penetration of the oil into the floor:

1st coat - Only linseed oil
2nd coat - 3:1 linseed to paint thinner
3rd coat - 2:2
4th coat - 1:3

Boiled linseed oil contains solvents and is highly toxic, while eco-friendly linseed oil can be expensive. “As a compromise, we take raw linseed oil and put it in the sun in shallow pans covered with a piece of glass, leaving a tiny air space. The oil pre-oxidizes and dries faster. It’s called sun-thickened oil.” [8]

Stabilizers

The main categories of binders used for earth construction are Portland cement, lime, bitumen, natural fibre and chemical solutions such as silicates. Benefits of cement addition is improved structural integrity, while a downside is reduced permeability of earthen mixture and thus natural ability of earth to allow passage of moisture throughout the soil mass is reduced. [10] Tests have indicated that there is an optimum lime dosage for a soil beyond which compressive strength decreases. The likely dosages are between 6-12% lime by dry weight and will increase as clay content increases. [10]

Alternative Infill

Introduction

Infill is used in conjunction with frame or post-and-beam style structures to fill in the wall spaces. In such styles, a wood frame or concrete column and beam structure is used to hold up the roof and provide structural support, while the infill is used to seal the building from the elements, as well as provide thermal mass and insulation. Infill is usually considered non-structural, however it can increase lateral support depending on the type. [11]

Ecoladrillo

“Eco-bricks” are a method of alternative infill that use plastic bottles and trash in the bulk of their composition. Bottles and trash are stacked and compacted into a wood frame and held secure by a layer of chicken wire on each face. The two faces are then plastered smooth.[12] Any inorganic waste material can be used to fill the bricks, however ideal materials are those that cannot be recycled others. Examples include: food packaging, old socks, razor blades, used up pens and markers, clothing tags, cotton swabs, etc. The process of "up-cycling" such materials that would otherwise end up in the trash reduces waste and significantly cuts construction costs. [13]

That being said, not all trash makes for good infill material. Anything organic such as food waste will not work. Trash must be clean and moisture free, as well as the bottles, and it is best to stay away from paper waste if at all possible. It is also important to stuff bottles as full as possible to increase insulation. Training of community members about these material requirements is important to ensure a stable and safe structure.[14]

Papercrete

Papercrete is a method of building traditional style cinder blocks out of paper. Soaked and shredded paper is mixed with sand and a binder such as portland cement or clay, and then compressed into a block mould. Papercrete blocks can be stacked and mortared with papercrete mortar and used as a substitute for traditional concrete blocks. [15]

The type and quality of paper can vary depending on availability. Newsprint or office paper is ideal, but any grade of paper that can be re-pulped will work. Paper that is waterproof and/or has a wax or plastic component such as butcher paper, cardboard, and juice cartons cannot be easily separated in water and will not work. [16]

The ratio of sand is dependent on the needs of the papercrete. A mix with more sand and less paper will dry faster, shrink less, and have more thermal mass and compaction strength. A mixture with more paper and less sand will be provide more insulation and will have more tensile strength, reducing the need for re-bar or other types of tensile supports. If your source of paper is free, more paper will also reduce material costs.[17]

Disadvantages to papercrete in comparison to traditional concrete include:

  • Longer drying time, especially in humid climates
  • More vulnerability to fire
  • More vulnerability to mold growth
  • More vulnerability to water damage

Advantaves to papercrete include:

  • More dimensional stability under different types of stresses
  • Significantly lighter than traditional block
  • High insulation (R-value of 2 per every half inch)
  • Resistant against rodent and insect infestation[15]

Sawdust

When considering sawdust as a building material, there are functionally two different types wood: hardwood and softwood. The quality of the sawdust will vary depending on the species, but most hardwoods are relatively better than softwoods at absorbing water, which are typically harder and grainier. For this reason, sawdust gathered from hardwoods is more ideal. Sawdust can be used in mixes with clay to make adobe and cob or with cement to make concrete and plaster substitutes. It can provide insulation, protection against freezing. It can also be found for free.[18]

Cob and adobe are made from mixtures of clay, sand, lime, sawdust and/or green waste. The ratio's can vary greatly depending on availability and quality of materials, making cob and adobe very adaptable building materials. Because Las Malvinas has an abundance of sawdust, the ratio with the most potential requires 9 parts sawdust, 3 parts clay, 2 parts lime, and 1 part sand. The sawdust is soaked overnight and dried for a few hours, then mixed by hand or by hoe with the rest of the mixture and water.[18] The amount of water need varies depending on the moisture content already present in the clay. The mixture can be made into adobe bricks or built up in monolith. Cob or adobe made with more sawdust rather than green waste will also dry faster.[19]

A mixture of sawdust, sand, and cement can also be used in infill. The mixture requires less cement than concrete or traditional cement plasters, however there is little information regarding its structural integrity. The common ratio is 3 parts sawdust, 2 parts sand, and 1 part cement, and the final mixture can be used as a plaster over another alternative infill material such as eco-brick.[20]

Structure

Exterior walls

Lay out the wall location on the sub floor where the wall's bottom or sole plate will be positioned. Measure from the outside edge of the subfloor, the width of the sole plate plus the sheathing, if the sheathing extends to the sub floor; or the width of the bottom plate if the sheathing extends over the boxing joist to the concrete foundation wall. Snap a chalkline. Select straight stock for the bottom and top plates, square of one end of each plate, and lay them side by side on the subfloor. If the plates have to be made out of more than one piece of lumber, make sure they join over a stud centre. Measure and mark the locations of the door and window opening centres, openings located from centres, partitions and studs. [21]

Marking Top & Bottom Plates

Standard walls are 8' to 12' high. Older homes and warmer climates will have 2x4 wall studs. Wall studs are generally spaced 16" on center. The first stud will sit on the end of the plate. Measure and mark 15-1/4" from the end for the near edge of the second stud. From this mark make marks every 16" for the near edges of the remaining studs. Before starting the layout process, chalk line the locations of the walls and their window/door openings on the subfloor. These marks will enable you to visualize and check the project's layout before the walls are made. The chalklines also serve as guidelines when actually raising the walls into place. [22]

Assembling Walls & Corner Posts

We usually assemble the wall on the floor, nail it together, then raise it into place. Working on a level surface is a major help in laying out the walls flush. Try to avoid assembling walls on the ground.

Check- It's a good idea to check for squareness by measuring diagonally from the corners after nailing on each end and after each wall is assembled.

Where two walls meet in a corner there needs to be some extra framing to make sure that there's something on each wall for the drywall on both walls to nail into. One wall at every corner needs a corner "post." Here are two ways to create one:

1) Add 2x4 spacer blocks between the end stud and then install an extra "corner stud."

2) Lay an extra corner stud sideways, flush with the inside edge of the bottom plate.

Once the corner post is secure, insulate the cavity before installing the sheathing. Once the sheathing is on and the wall goes up, the end of one wall section will cover the corner of the other making insulating impossible at that point. [22]

Plank and Beam Construction

In the plank and beam framing method beams of adequate size and to support floor are spaced up to eight feet apart. Floors and roofs are covered with a two inch plank. These serve as sub-flooring and roof sheathing, and where tongue and grove is used provide a great finished look. [23]

Concrete Foundations

With unstable soils, and it wet climate where re-enforced concrete is used with Masonry blocks walls typically have a 1/2 inch coat of portland cement applied to the exterior. Once set this is then covered with asphalt to resist water penetration of the walls by water. [23]

Corrugated Tin Roofing

Corrugated tin roofing is commonly used in tropical areas because of its durability, sturdiness, and light weight design. The key attribute leading to the ability to remain useful for so long is due to the special corrugated shape the metal is formed to. [24] Main types of metals used are aluminum, galvanized steel, copper, aluzinc, and tin. [25] Integrated ventilation is very important since this style of material if often used in tropical, humid climates. It is meant to provide insulation from heat during most of the year, so to "provide generous wall openings, large doors and windows" is key during the construction of the roof. [26]

References

  1. ↑ (2012). "Central America and the Caribbean: Dominican Republic." <https://www.cia.gov/library/publications/the-world-factbook/geos/dr.html> (Jun. 16, 2012).
  2. ↑ 2.0 2.1 "Insights from the field: Appendix B." <http://www.peacecorps.gov/wws/publications/insights/pdf/InsightsBackground.pdf> (jun. 16, 2012)
  3. ↑ Elliot, D., Shwartz, M., George, R., Haymes, S., Heilmiller, D., Scott, G. (2001). Wind Energy Resource Atlas of the Dominican Republic, Natural Renewable Energy Laboratory.
  4. ↑ (2012). "PCDR facts." <http://dominican.peacecorps.gov/pcdr.php> (Jun. 16, 2012).
  5. ↑ Timbers, Amelia (2008). "Green Flooring Down to Earth." <http://www.matternetwork.com/2008/5/green-flooring-down-to-earth.cfm> (Jun. 16, 2012).
  6. ↑ Team Planet Green, (2009). "Rammed Earth Flooring Guide." <http://planetgreen.discovery.com/feature/green-materials-guide/flooring-rammed-earth.html> (Jun. 16, 2012).
  7. ↑ Sirna, Tony (2012). "How To Pour A Rammed Earth Floor/Adobe Floor." <http://www.dancingrabbit.org/about-dancing-rabbit-ecovillage/eco-living/building/natural-building/earthen-floor/> (Jun. 16, 2012).
  8. ↑ 8.0 8.1 8.2 Tobias, Lori (2003). "Feet on the Ground: Earth Floors." <http://www.naturalhomeandgarden.com/article.aspx?id=2064> (Jun. 16, 2012).
  9. ↑ Ziggy, (2008). "Natural Building 101: How To Build an Earthen or Adobe Floor." <http://greenbuildingelements.com/2008/11/06/natural-building-101-how-to-make-an-earthen-or-adobe-floor/> (Jun. 16, 2012).
  10. ↑ 10.0 10.1 Maniatidis, V., Walker, P. (2003). A Review of Rammed Earth Construction, Natural Building Technology Group.
  11. ↑ Dorji, J., Thambiratnam, D.P. (2009). "Modelling and Analysis of Infilled Frame Structures Under Seismic Loads." The Open Construction and Building Technology Journal, 3, 119-126.
  12. ↑ "Creating Green Communities." <http://www.mariposadrfoundation.org/Creating_Green_Communities.html> (Jun. 16, 2012).
  13. ↑ (2011). "Making eco-bricks." <http://bottleschools.org/wiki/Making_%E2%80%9Ceco-bricks%E2%80%9D> (Jun. 16, 2012).
  14. ↑ Kutner, Laura (2012). “Trash for Peace: Engaging Children, Youth and Community for a World without Waste.” Children, Youth and Environments 22(1): 294-303. <http://www.colorado.edu/journals/cye, http://scholar.googleusercontent.com/scholar?q=cache:-uEHRjTsIMwJ:scholar.google.com/+eco+brick+plastic+bottle&hl=en&as_sdt=1,5&as_vis=1> (June 12, 2012)
  15. ↑ 15.0 15.1 Hart, Kelly. "Papercrete." <http://www.greenhomebuilding.com/papercrete.htm> (Jun. 23, 2012).
  16. ↑ Fuller, Barry (2012). "Introduction to Papercrete." <http://www.livinginpaper.com> (Jun. 23, 2012).
  17. ↑ Mohammad, B. (2009). "Papercrete as Infill Materials for Composite Wall System." European Journal on Scientific Research, 34(4), 455-462.
  18. ↑ 18.0 18.1 Taylor, Charmaine (1998). "Building for free with alternative natural materials." <http://www.countrysidemag.com/issues/85/85-3/Charmaine_R_Taylor.html> (Jun. 16, 2012).
  19. ↑ "Making Cob." <http://www.pequals.com/at/natoven/making_cob.htm> (Jun. 16, 2012)
  20. ↑ Andrews, Russell. "Sawdust, Sand and Cement." <http://www.rainforestinfo.org.au/good_wood/sawment.htm> (Jun. 16, 2012).
  21. ↑ Hunter, Ronald (2011). "How To Frame Exterior Walls On A Platform 1." <http://www.basiccarpentrytechniques.com/Framing%20Exterior%20Walls.html> (Jun. 16, 2012).
  22. ↑ 22.0 22.1 (2008). "Framing." <http://www.hometime.com/howto/projects/framing/frame_3.htm> (Jun. 16, 2012)
  23. ↑ 23.0 23.1 (2001). Details for Conventional Wood Frame Construction, American Forest & Paper Association.
  24. ↑ (2011). "What is Corrugated Metal Roofing?" <http://www.corrugatedmetalroofing.net/whatis.html> (Jun. 16, 2012).
  25. ↑ (2012). "Insulated Corrugated Roof Construction." <http://www.appropedia.org/Insulated_corrugated_roof_construction> (Jun. 16, 2012).
  26. ↑ Bradley, Bill (2012). "Low Cost Building in the Tropics - Tropical Building." <http://www.builderbill-diy-help.com/tropical-building.html> (Jun. 16, 2012).
Retrieved from "https://www.appropedia.org/w/index.php?title=Las_Malvinas_ecoladrillo_schoolroom&oldid=210986"
Cookies help us deliver our services. By using our services, you agree to our use of cookies.