The objective is to construct a classroom that will hold approximately 25 students under the age of 10. The classroom will be constructed using primarily locally sourced materials and will explore alternative building methods. The classroom be at least equally as durable as with conventional construction methods and will be cost efficient.
Background[edit | edit source]
Las Malvinas II is a community in Santo Domingo Norte. Santo Domingo is 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.
As there is an abundance of both plastic bottles and waste paper, the alternative construction methods that are most appropriate are the use of papercrete and ecoladrillo. Papercrete is similar to concrete blocks but are made with recycled paper. Ecoladrillo uses wooden frames, plastic bottles, chicken wire, and concrete in the construction of walls.
Criteria[edit | edit source]
|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[edit | edit source]
See Literature Review for relevant research completed for this project.
Final Design[edit | edit source]
The final design is a traditional concrete column-and-beam style structure with alternatively constructed, non load bearing infill. The alternative material used throughout the infill is primarily ecoladrillo. Papercrete is used in a section of one of the windows. Resourced waste wood is used as panels between the beams and roofing that allows for ventilation. The floor is tiled with discarded broken tiles from a factory, using an ancient Roman technique of laying tile floors.
Ecoladrillo[edit | edit source]
Ecoladrillo is made from clean plastic bottles and trash, wood, chicken wire, and plaster. The plastic bottles and trash make up the majority of the wall. Plastic bottles are stuffed with clean non-organic trash and are then stacked into a wooden frame with chicken wire stretched over each face to hold everything together. A plaster is then applied to each face.
It is important for the chicken wire to fully reach the columns and beams so that the plaster can fully reach and bind with the columns and beams (plaster does not adhere well to bottles without chicken wire).
Sawdust Plaster[edit | edit source]
Due to the availability of sawdust as a waste product from a local coffin manufacturer we came up with a formula for sawdust plaster. The interior has 3 layers of sawdust plaster. The first 2 are of the ratio described below, and the final finish layer has additional cement added to the mix. The exterior has 2 layers of sawdust plaster, both of the ratio described below. A third finish layer is then applied that does not use any sawdust. This finishing layer is a traditional cement plaster to which we added iron oxide, a natural pigment, to dye the walls yellow thus eliminating the need for paint. The edges between the columns and beams and the walls on both the exterior and interior are cut in using a traditional cement plaster due to the difficulty in getting the sawdust plaster to bind with the dry concrete of the columns and beams.
A good size mix uses 22 gallons of sawdust, 2 gallons of lime, 16 and 1/2 gallons of sifted sand, 1 bag of cement, and roughly 20-22 gallons of water. This produces roughly 40 gallons of plaster which covers roughly 1 coat on 10 square meters of wall, depending on the thickness being applied.
Papercrete[edit | edit source]
Papercrete is a method of building traditional style concrete blocks out of paper. Soaked and shredded paper is mixed with sand and cement 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.
A block pressing machine compacts the mix and reduces the drying time by nearly 100%. This is important because in humid climates such as in Santo Domingo a shortened drying time is crucial to expanding the possibilities of papercrete.
Cost/m2 of Wall Area[edit | edit source]
Ecoladrillo With Sawdust Plaster[edit | edit source]
|Materials||Unit Price (RD$)||Quantity||Total/m2 (RD$)|
|Wire, 17'/lb, 10 gauge||$36/lb||0.5 lbs, 9 ties||18.00|
|1cm Chicken Wire, 3'wide||$66/yard||2.5 yards||165.00|
|2"X4", Pine||$15/boardfoot||2.5 boardfeet||37.50|
|Portland Cement||$267/ft3||0.4 ft3||72.09|
|River Sand||$750/m3||0.01 m||7.50|
|Total Cost / m2 of Wall Area||$314.59|
Traditional Concrete Block[edit | edit source]
|Materials||Unit Price (RD$)||Quantity||Total/m2 (RD$)|
|Concrete Block, size 6||$20||10||200.00|
|River Sand||$750/m3||0.2 m3||15.00|
|Portland Cement||$267/ft3||0.36 ft3||96.12|
|Rebar 3/8"||$7.75/ft||9 ft||69.75|
|Total Cost / m2 of Wall Area||$380.87|
The cost of building ecoladrillo is slightly smaller per square meter than the cost of building with traditional concrete block. The trade off is that ecoladrillo is much more labor intensive and time consuming to build. If labor is not free or relatively cheap, ecoladrillo could easily become the more expensive material. However with the exception of labor, the most expensive component of building ecoladrillo is the chicken wire. Chicken wire has many alternatives, most of which are more expensive, however exploring cheaper alternatives would be an effective way of further lowering the costs.
Timeline[edit | edit source]
For a day-by-day timeline with photos please visit the Timeline page.
Discussion and Next Steps[edit | edit source]
Many new alternative construction methods are incorporated in the classroom at Las Malvinas II. In addition to the ecoladrillo infill and sawdust plaster, there is recycled broken tile flooring, recycled particle board upper infill, and some minor use of papercrete block. We are excited at the prospect of the continued interest and availability of the local block manufacturer in the process and production of papercrete. The use of sawdust as a major component in plaster is also new and we are looking forward to seeing how the plaster performs over the next year. As with all new methods and materials, there were numerous issues encountered in the development and implementation of all these alternative materials. Some of those issues as well as plans for future material development will be discussed in the following sections.
Discussion[edit | edit source]
The main issue regarding the construction of ecoladrillo infill is the insufficient amount and placement of wire to tie and tighten the chicken wire flush to the wall. Wire ties are secured to the rebar within the columns and beams at 20 cm increments, however none are placed at the corners where columns and beams or columns and floor met. In some places wire is nailed into the corner, offering a less secure but passable solution, but in others the only solution was to tie the interior chicken wire to the exterior to lock in the bottles and to keep the chicken wire from flaring out. However, this solution results in the chicken wire being less taught and creates a gap between the chicken wire and the corner which ultimately has to be filled in with mortar. The more taught and secure the chicken wire, the less severe the walls can potentially bow out. The more flush the chicken wire is with the columns and beams, the easier it is to apply the plaster and the less likely it is that the plaster will crack. The lesson learned is to overestimate the quantity of wire needed and to never neglect the corners.
The sawdust plaster mix and the papercrete block mix share a similar difficulty. Water retention in sawdust and in paper is significantly high, so when adding soaked sawdust or soaked paper to a mix, the water in those materials alone can make the mix overly wet and unusable. We found that equal parts water and sawdust is enough to fully soak and submerge the sawdust without making the final plaster mix too wet, however there is no way to adequately soak and repulp paper for papercrete without making the paper too wet. Pressing the paper dry before adding to the mix is a passable solution, but it is labor intensive and causes the paper to clump, weakening the integrity of the mix. The best solution is to lay out the wet paper pulp on a tarp to dry in thr sun, however, that can take up to 3 days in a humid tropical climate such as the Dominican Republic.
Next Steps[edit | edit source]
The next things to happen regarding the schoolroom in Las Malvinas II are:
- Interior walls are to be painted with a lime wash
- Liter of Light may be installed
- Interior will be readied for use
- Observations will be made and recorded regarding the durability of the walls
Updates[edit | edit source]
- Interior has been readied and classes have started
- Interior has been painted with a lime wash