The Botica Popular as of July 7, 2013. Outer walls are of HullKrete, inner wall of ecoladrillo. The roof has been donated.
Error in widget YouTube: Unable to load template 'wiki:YouTube'

Introduction

This project was part of the Summer 2013 Practivistas Dominicana project, led by Lonny Grafman in the Dominican Republic. Five students, three from Humboldt State University (HSU) in California and two from Universidad Iberoamericana (UNIBE) in Santo Domingo, collaborated with the community of Las Malvinas to construct three walls for a "Botica Popular" in the community. This experimented with cinder blocks, or concrete masonry units (CMUs) made of various upcycled materials such as sawdust, paper and rice hulls mixed with cement and pressed using an industrial cinder block maker. At the same time another team worked on building the other two walls out of ecoladrillo, or upcycled plastic bottles.

Las Malvinas is a rural barrio on the Northern outskirts of Santo Domingo, next to the La Isabela industrial zone. Las Malvinas and Practavistas began working together in 2012, when together they built a schoolhouse out of ecoladrillo and papercrete blocks. Through a series of public meetings Las Malvinas community members have identified and prioritized a list of needs. On that list are access to running water and medicine. To address the need for water a team of motivated community leaders constructed a large cistern (approx. 50 cubic meters). An engineer from UNIBE assisted in the design. To address the need for medicine the two student teams mentioned above will work with community members to construct a Botica Popular. The Botica Popular sits partially on top of the cistern and is approximately 6 meters long and 3 meters wide.

Botica Popular

Boticas populares are neighborhood pharmacies that provide medications at cost price. They are part of government public health campaign called El Programa de Medicamentos Esenciales or "Essential Drugs Program" (PROMESE). Established in 1984 by presidential decree, PROMESE is the Dominican Republic's central supplier of medications and medical supplies with a mission of ensuring quality, low-cost access to the nation's public health system, Sistema Publico Nacional de Salud. PROMESE has provided greater medical coverage to the population by optimizing public health spending with the implementation of an economy of scale and buying medications and medical supplies in larger volumes[1]. The "Essential Drugs Program" directly serves public and military hospitals, boticas populares, and rural clinics.

For boticas populares, the program fronts the medications and accepts payment at cost price upon distribution to the patient. Las Malvinas does not have a local clinic or hospital. The nearest hospital is Moscosos Puello about 5 km away.

Objective

The community of Las Malvinas is seeking to construct a Botica Popular, or government-funded pharmacy, in their community. The objective of this project is to build two of the four walls of the Botica using alternative masonry and to erect the complete Botica by 5 July 2013. This student team will fabricate building blocks with sawdust, rice hulls or paper mixed with cement and pressed in an industrial block press. With the climate in the Dominican Republic, the blocks need to be able to withstand heat, rain and the test of time.

Part of the objective of this project is to find a building material, specifically a fiber-concrete mixture, that the community will be able to utilize in the future to make more blocks for other projects. As such, final product should be composed of locally purchased or acquired materials, and have a low cost, both monetary and environmental.

Entirely concrete cinderblocks have a high embedded energy, with an average of 0.67 MJ/kg and 0.073 kg Co2 per kg with a density of 1450 kg/m3[2]. The new blocks should have less embedded energy per block.

Criteria

This section was designed to assist in the determination of the different aspects of this project. The group chose these criteria based on the expectations of the client, the class and personal interest. Weighing the criteria allows for focus on certain elements of the project to ensure satisfaction with the final product.

Criteria Constraints Our Weight (0-10)
Aesthetics Must resemble local architecture 6
Production Cost Must cost less to produce than the common cinder block 10
Durability Must withstand elements, impact and pressure 9
Material Locality Must attain materials within or near Las Malvinas 7
Potential for Reproduction Ease of access to materials as well as documentation 8
Safety Must be safe both structurally and in the process of creation 10
Community Involvement Must include the local community members in the creation of this project 10
Environmental Impact Blocks should have a smaller footprint than concrete blocks 7

How To

Make papercrete

Image Step
LM 2013 papercrete newspaper 1.JPG
Gather materials. We received misprinted newspaper from Listin Diario - a newspaper based in Santo Domingo. Cost was minimal, they only asked for what they would otherwise have received from the recycling center. Sand, cement, lime, rice hull ash and drying agent were also used in our blocks. The drying agent was necessary due to continual rains and the slow drying time of paper and rice hull blocks.
LM 2013 tearpaper papercrete.JPG
Tear paper for pulping. Initially we did this by hand, but later we has access to a paper shredder (recommended)
LM 2013 Soakpaper papercrete.JPG
Soak paper in water and lime. Approximately 1/8 bag of lime was used in a 55 gallon barrel full of paper and water. Paper should be soaked overnight before pulping, although we also experimented with dry-pulping paper.
LM 2013 pulppaper papercrete.JPG
Pulp paper. We used a drill and ingenious welded attachment for pulping. Paper should be throughly wet for the pulping process for ease of pulping and to make smaller pulp. We experimented with pulping only damp paper to decrease drying time, however due to some confusion in block placement after pressing we were unable to tell how this affected the blocks. Drier paper cannot be pulped as thoroughly as wet paper, and this could account for a discrepancy we discovered in the strength of our papercrete blocks.
LM 2013 Stomppaper papercrete.JPG
Dry the paper. It should be moist but excrete no water when squeezed so that excess water will not disrupt the ratios in the mixture and wash away cement in pressing. Ideally we tried to do this in the sun to avoid compaction of pulped paper, however due to continued rain we resorted to other means of drying the paper. We put the paper in rice hull bags and pressed it to remove excess moisture before laying it in the sun. This significantly accelerated drying time and we dry-pulped it afterwards to reduce large chunks. Dry-pulped paper did not have to be pressed and thus did not have to be re-pulped. Another method that was suggested was a centrifuge, and this would likely be effective.
LM 2013 Pressedblocks papercrete.JPG
Mix and press. We had access to an industrial cement mixer and block presser for this step. The final mixture we used for papercrete was 3 wheelbarrows pulped and dried paper (assuming one wheelbarrow = 5 five-gallon buckets), 1.5 wheelbarrows sand, 2 five-gallon buckets of rice ash, 1 bag cement and 6 fluid ounces of Vinaldom SA-600, the quick-drying agent. Water was added as needed.
LM 2013 moveblocks fibercrete.JPG
Have caution after the blocks are pressed to minimize breakage in between the machine and the drying area. Carrying by hand is recommended.
LM 2013 wetblocks fibercrete.JPG
Wet blocks periodically as they dry to reduce cracking and ensure proper set of blocks. Papercrete tends to hold moisture so use discretion.

Make HullKrete

Image Step
LM 2013 Gathermaterials HullKrete.JPG
Gather materials. We received a donation of rice hulls and rice ash from a nearby distillery that burns the hulls for energy. Sand and gravel were donated from the block factory and cement was purchased from the same. A quick-dry additive, Vinaldom-600, was purchased at a nearby ferreteria (hardware store).
LM 2013 bagscommala hullkrete.JPG
Prepare mixture - we had two final successful mixtures. The first mixture contained 2.5 wheelbarrows (1 wheelbarrow = 5 five-gallon buckets) of rice hull, 2 wheelbarrows sand, one wheelbarrow gravel, one bag cement and 4 fl. oz of the V-600. The second mixture was exactly the same with and added half-wheelbarrow of rice hull, bringing the total up to 3.
LM 2013 mixing hullkrete.JPG
Mix thoroughly and press, we used and industrial cement mixer and mixed dry ingredients first, adding the drying agent diluted with water. Add water until the mixture holds together, but is not overly saturated.
LM 2013 crackedblocks hullkrete.JPG
Have caution after the blocks are pressed to minimize breakage in between the machine and the drying area. Carrying by hand is recommended.
LM 2013 wetblocks fibercrete.JPG
Wet blocks periodically as they dry to reduce cracking and ensure proper set of blocks. This is particularly important in hot areas, try to keep blocks out of direct sunlight if this is the case.

Price Comparison

We conducted a price comparative analysis between the final block mixes and the blocks made at the factory. Both the blocks of rice hull and the blocks of papercrete were cheaper than standard blocks found at the factory based upon price comparisons of materials. Click this link to view the chart, which also includes the final mixtures we used and the number of blocks from each mixture. Fibercrete price Comparison.pdf

Budget

Following is our budget for this project. Costs in both Dominican pesos (DR $) and US Dollars (US $) are included.

Material Quantity Source Cost per unit (DR$) Cost per unit (US$) Total Cost (US$)
Rice Hulls 35 bags Collected from the brewery 200.00 4.90(labor and bag purchase) 4.90
Paper 550 pounds Acquired from Listin Diario 580.00(recycle fee), 800.00(shredding) 14.00(recycle fee), 19.50(shredding) 33.50
Cement 21 (94 pound bags) Purchased from block factory 280.00/bag 6.83 143.43
Lime local hardware store 50.00/bag 1.22/bag 12.20
Sand and gravel buckets Provided by block factory 0.00 0.00 0.00
Rice Fly Ash 3 bags Provided by brewery 0.00 0.00 0.00
Paper pulper Attachment for power drill Created by community member
Building materials Buckets, barrels, applicators, shovels, etc. Borrowed from various community members 0.00 0.00 0.00
Transportation of materials Use of trucks Community members 0.00 0.00 0.00
Tarp 1 large Hardware store
Safety equipment Gloves and dust masks Local stores 164.00/gloves 82.00/masks 4.00/gloves 2.00/masks 6.00
Block pressing machine and mixer Presses 4 blocks at a time Block factory 0.00 0.00 0.00
Sawdust 4 barrels of various textures Acquired from coffin maker 0.00 0.00 0.00
Secante (cement drying agent) 1 gallon Purchased from hardware store 400.00 9.75 9.75
Total Cost $209.78

Timeline

This timeline includes information about our progress throughout the project. It records the amount of time and preparation involved in creating both the blocks and the constructing the Botica Popular.

Friday June 7, 2013

  • Summer 2013 sawdustcrete1.JPG
    Our group had an opportunity to meet Jacob, an Engineering student at UNIBE who showed us his experiments with sawdust-concrete and recycled styrofoam-concrete. He had been experimenting with different ratios of sawdust to concrete and testing the strength of different mixes. His experiments also included using wire to increase the tensile strength of the concrete slabs. He will likely be a useful contact while working on this project.

Making Blocks

Saturday June 8

  • First day to work on mixes. We went to Las Malvinas in the morning and, with Ginger's help, secured a barrel of sawdust from the coffin manufacturer who will be providing that material and the block-making site next door where we and members of the community will be doing experiments and making blocks with sawdust and other materials. We also were given two bags of lime and loaned two barrels for mixing the sawdust, lime and water to soak. After an initial mix, the owner of the plant arrived and made some changes to the mixture we had put together, encouraging us to "go big" with our experiments. There was a high level of interest from the community members who came to work with us - they really ended up taking over much of the work, sifting, mixing and all the while peppering us with questions. A kid from the community spent most of the afternoon with us helping mix the sawdust, lime and water. We will be returning to the site on Wednesday to try more mixes and Thursday is the day to press blocks.

Wednesday, June 12

  • Our sawdust for blocks. We tested with both pre-soaked sawdust and dry sawdust.
    We returned to Las Malvinas and found our sawdust mixture in good shape. The coffin manufacturer next door gave us two more barrels of sawdust and we doubled the amount in our existing bucket, making a moist, but much drier, sawdust and lime mixture. The owner of the block making company will be allowing us to use his industrial cement mixer (if we have enough mix to fill it). We also discovered that there is not only ample rice hulls nearby, but ample ash from burnt rice hulls that is a waste product and the cement company already uses it. So we will be experimenting with using rice hull ash as well to reduce the amount of cement in our mixtures.

Thursday, June 13

  • Sawdust-crete fresh off the press
    First day of block making for our first tests! We ended up with four mixes, three of sawdust and one of rice hull. We totaled 113 blocks with three bags of cement, and that was good because at the site they usually make around 33 blocks per bag, so we are at least on par with their mixes in terms of cement used. The owner not only allowed us to use their machine, but also their industrial cement mixer. It was an excellent learning experience for all concerned, and testing the blocks begins on Saturday. We also obtained two barrels of very fine sawdust to experiment with in our next mixtures.
Ingredient Type of measurement Mix 1 Qty Mix 2 Qty Mix 3 Qty Mix 4 Qty
Sand 5 gallon bucket 2 2 1.5 1.5
Gravel 5 gallon bucket 0 2 0.5 0.5
Sawdust 5 gallon bucket 14 14 10 0
Rice Hull 5 gallon bucket 0 0 0 10
Cement Bag (90 lbs) 1 1 0.5 0.5
Rice Hull Ash (RHA) 5 gallon bucket 1/4 1/4 1/6 1/6
Lime Bag (approx. 1 5-gallon bucket) 1 1 2/3 2/3
Number Blocks 27 39 23 24
Compression Test Crumbled Crumbled Crumbled Held up


Saturday, June 15

  • First round of dry HullKrete
    We returned to Las Malvinas to test the blocks from Thursday. The rice hull blocks were nearly dry and the sawdust blocks were not dry yet. The rice hull blocks appeared the most structurally sound, although it is difficult to ascertain with the sawdust blocks still being so wet. Pulerimo, a community member, offered his advice that the blocks do not have enough cement, which is making them crumble. Our next mixtures will contain a greater amount of cement, and likely of RHA as well. It is possible that we will focus on rice hull blocks for the Botica, although we need to do more experimentation before that is certain. Work continues on the cistern, which will be part of the foundation of the Botica.

Sunday, June 16

  • Ricecrete blocks hold up in the compression test
    Work continues on the cistern, which will form the base for half the Botica.
  • Assessed the blocks again, sawdust blocks are still wet, rice hull blocks are closer to dry. The sawdust may not be used in the final round, testing will continue before this is a final determination. The rice hull blocks were found capable of supporting human weight, and general consensus is that they will work well with more cement. Papercrete is also going to be tested in the next round.
  • The very fine sawdust from the coffin manufacturers proved challenging to sift. It may not be used in blocks, it might be used in the finish for the Botica.

Monday, June 17

  • Sought sources for waste newspaper. Attempted several contacts.
  • Determined plan of action for block testing round 2.

Tuesday, June 18

  • A source for newspaper for making papercrete was secured.
  • We tore up and set paper to soak in water and lime for testing on Thursday or Friday.
  • Determined that using the 4 inch sized block forms will not make a significant difference for the tests: the forms in the machine will not be changed back to 6 inch blocks until Monday.
  • Seeking a paint mixer to pulp the paper for blocks.

Wednesday, June 19

  • A paper-tearing party on a sunny afternoon
    Spent at least 3 hours tearing paper for block making several kids from the community came to help. We added more paper to the existing mixture and are hoping to find a paint mixer or similar for tomorrow. If one can't be found we may have to think of some other method to pulp the paper.
  • Secured the rice hull source for tests and block making, we should have rice hulls to use tomorrow.
  • Joel found an admixture that we can use to accelerate the drying of the blocks. We will be experimenting with adding it when we make the test blocks.

Thursday, June 20

  • 30 bags of rice in Julio's truck
    Went to a brewery nearby Las Malvinas and obtained 30 bags of rice hull for block making. Upon measurement, each of these bags hold approximately 7.5-8.5 5 gallon buckets of rice hull.
  • Worked on leveling the area that will be underneath the floor of the Botica, it was built up with a large pile of dirt from the cistern.
  • Discussed need for a paper pulper. Initially we were going to find a paint mixer, however some community members knew a welder nearby who would be able to weld us a tool for pulping paper.

Friday, June 21

  • Tore more newspaper
  • The paper pulping machine in its final incarnation
    We received the new paper pulping bit and drill today. It underwent a few changes from its original state and worked well to pulp the paper we had set to soak. We worked with different amounts of water in the paper mixture in order to determine how much was needed to pulp the paper most effectively and not leave it too wet for block making.

Saturday, June 22

  • In order to dry out the paper we soaked, the pulp was put into rice hull bags and pressed by stepping on it until it was dry enough to be used in the mixture. This was even more effective with the added weight of giving a kid a piggy back ride.
  • One the paper was dry enough and the workers were ready, we pressed six more mixtures, this time adding a drying agent to accelerate the rate of set and reduce dry time of the blocks. None of these mixtures contained sawdust.
Block Test Round 2
Ingredient Type of measurement Mix 5 Qty Mix 6 Qty Mix 7 Qty Mix 8 Qty Mix 9 Qty Mix 10 Qty
Sand 5 gallon bucket
Gravel 5 gallon bucket
Paper Pulp 5 gallon bucket
Rice Hull 5 gallon bucket
Cement Bag (95 lbs)
Rice Hull Ash (RHA) 5 gallon bucket
Lime Bag (approx. 1 5-gallon bucket)
AS 600 (Drying Agent) Fluid Ounces
Number Blocks
Testing
1 wheelbarrow=5 five-gallon buckets

Sunday, June 23

  • Plastering commenced on the cistern today, and some of our group had the opportunity to help with that process and learn cement plastering skills.
  • More paper was pulped and torn today as well as laid out to dry for the next block pressing

Monday, June 24

  • Weighing out 300 lbs of paper from Listin Diario
    Acquired about 300 pounds of newspaper from Listin Diario.
  • Shredded more paper by hand, Joell contacted a friend with a paper shredder to accelerate that process.
  • Pulped paper and set out on a tarp to dry in the sun. This process has been slowed by daily rain.

Tuesday, June 25

  • Pulped the paper from the day before.
  • Worked to dry paper for pressing blocks on Thursday
  • Received the shredded paper in the evening and set it to soak.
  • First HullKrete blocks are laid for the Botica!
    Work begun on the Botica. Community members determined that the blocks from the previous round of tests are strong enough to build with and began work on the storage room for medicines.

Wednesday, June 26

  • Discussed block pressing with respect to day, community involvement and mixes to use. We are working on a spreadsheet to determine the relative cost of different blocks to aid in determining which mixture to use for the Botica.
  • Pulped more paper for block pressing tomorrow.

Thursday, June 27

  • Pulped and dried more newspaper, we are going to experiment with pulping methods. One version of paper pulping involves immersing the paper in water and pulping while very wet, then allowing the paper to dry before adding it to concrete. Another possibility is that the paper can be wetted minimally and pulped, allowing for more expediency in the making of papercrete.
  • A sudden rainstorm kept us from being able to press blocks, they shall be pressed tomorrow instead.

Friday, June 28

  • Pulped yet more paper.
  • Lay paper out to dry=.
  • Made first part of blocks for the Botica, three different rice-hull crete (HullKrete). Because of measuring error, one set of blocks had to be retried. The owner of the block factory offered a mixture of his own and we also re-tried the first HullKrete mixture with increased cement.
  • Re-analyzed the spreadsheet for determining relative cost of fibercrete blocks versus conventional blocks.
  • Communicated with Jacob to see if he is interested in testing the blocks at UNIBE with a machine. He is, and the tests will take place on Monday.
Final Blocks/Final Test round 1
Ingredient Type of measurement HullKrete Final Weirdness HullKrete Vasquez Final Original HullKrete Revisited
Sand 5 gallon bucket 10 10 3
Gravel 5 gallon bucket 2 5 1
Rice Hull 5 gallon bucket 15 12.5 20
Cement Bag (95 lbs) 1.5 1 1.5
Rice Hull Ash (RHA) 5 gallon bucket 1.25 0 0.5
Lime Bag (approx. 1 5-gallon bucket) 0 0 1
AS 600 (Drying Agent) Fluid Ounces 6 4 6
Number repetitions of mixture 2 1 1
Total Number Blocks 60 52 Machine broke halfway through pressing. Incomplete.
Testing
1 wheelbarrow=5 five-gallon buckets

Saturday, June 29

  • Pressed over 300 blocks: most were HullKrete with two different mixtures and there were three different mixtures for papercrete: one containing wet-pulped paper only, one with "dry - pulped" paper only and one with a mixture of the two. Work on the Botica recommences when the blocks are dry. Work continues on the cistern, and wood for the cap is being accumulated.
Final Blocks Round 2
Ingredient Type of measurement HullKrete Final Vasquez* Extra HullKrete Final Papercrete Final Wet Pulp Papercrete Final Dry Pulp Papercrete Final Mix
Sand 5 gallon bucket 12 (10 +2 of a sand-clay mixture) 12 (10 +2 of a sand-clay mixture) 7.5 7.5 7.5
Gravel 5 gallon bucket 5 5 0 0 0
Paper Pulp 5 gallon bucket 0 0 15 wet pulped 15 dry pulped 10 dry, 5 wet pulped
Rice Hull 5 gallon bucket 12.5 15 0 0 0
Cement Bag (95 lbs) 1 1 1 1 1
Rice Hull Ash (RHA) 5 gallon bucket 2 2 2 2 2
AS 600 (Drying Agent) Fluid Ounces 4 4 6 6 6
Number repetitions of mixture 3 1 1 1 1
Total Number Blocks
Testing
1 wheelbarrow=5 five-gallon buckets
*This mix was repeated and changed slightly

Building the Botica

Sunday, June 30

  • The wood for the cistern cap was placed today and the cap should be done within the next couple of days.
  • Johnny laying mexcla for blocks.
    Blocks that were pressed on Friday were dry enough today to use for construction, so several feet of height was added to the walls of the Botica storage area today. A cement and sand-based mortar is being used and the holes of the blocks for the storage area are being filled with concrete. The filling is added for increased security purposes.

Monday, July 1

  • The cap for the cistern was created. This involved tying in rebar on the wood cap and then pouring and leveling cement.

Tuesday, July 2

  • Blocks from several different mixtures were tested at UNIBE with the help of Jacob.
  • The cistern cap was dry today and building commenced.
  • All three walls are in progress and columns for the interior wall were built with blocks.

Wednesday, July 3

  • One wall completed, another one nearly finished and the third is approximately two thirds done. One more full workday and the walls will be finished.

Thursday, July 4

  • Second wall finished, third wall will be finished either Friday or Saturday.
  • Final presentations in La Zona Colonial Centro Cultural de Espana took place in the evening.

Friday, July 5

  • Final presentation and celebration in Las Malvinas.

Saturday, July 6

  • Plastering is under way on the walls.
  • A wood frame was build for pouring the biga - essentially a concrete cap to the walls that will increase the structural strength of the building.
  • Biga poured.

Sunday, July 7

  • Work continued in preparation for laying the roof of the Botica.
  • Ecoladrillo wall plastered
  • Plastering continues on the HullKrete walls, a truth window is added on the east wall.

Literature Review

Climate

  • Being located between the geographical coordinates 17 ° 30 and 19 ° 56 north latitude and 68 ° 19 and 72 ° 31 W, Dominican Republic is located in the tropical region. It has a very rugged relief, about 50% of its territory is occupied by five mountain ranges and three great mountain ranges, among which are the highest peaks of the Antilles (Pico Duarte 3,187 m)[3].
  • The Dominican Republic, due to its geographical position, has a tropical climate that is regionally influenced by topography, trade winds, and atmospheric phenomena[4].

Temperature

The Dominican Republic has an average annual temperature of about 25 °C (77 °F) which is defined as a warm tropical climate. The higher temperature, about 34 °C (93 °F), recorded in the months from June to August, and the lowest, 19 °C (66 °F), recorded between December and February[5].

Precipitation

In the Dominican Republic there are three rainy seasons: Season Front (November-April), Convective Season (May-July) and hurricane season (August-October)[6].

Components

At the block-making site where we have been allowed to press our blocks, they use a mixture of sand, gravel, cement and water to make their blocks. For our blocks, we are replacing sand and gravel with other materials and in using rice hull ash and lime we hope to utilize less cement, making a cheaper and lighter block. The mixture used on-site that we are comparing to is 3 wheelbarrows of sand, 1 wheelbarrow of gravel, 1 bag of cement and 2 buckets of water, which makes around 33 blocks. [7]

Sand & Gravel

Cement is not enough to make a block by itself. Sand and gravel give blocks their structure, held together by cement "glue". In these experiments we are mostly replacing sand and gravel with our alternate materials.

Lime

  • For this project, we will be using lime in several stages. It is an ingredient in the upcycled cinder blocks and plaster because of its ability to prevent water damage. Mg and CaO are the active ingredients in lime. While other components in the lime can be present, they are considered impurities in the mixture. Hydrated lime is expressed as CaO+H2O>Ca(OH)2, which is the powdered dry material often used in plasters[8]. The hydrated lime then needs to be rehydrated in a process called "slaking". The action of slaking lime is a process of adding water to the powdered lime mixture until the powder can not absorb any more water. The CaO is responsible for this behavior of absorption and reaches a limit which becomes obvious due to a layer of excess water on top of the lime slurry.[9]
  • Lime can also be used as a component for mortars, plaster, and a final lime wash. Plasters can be applied to moistened surfaces, upon which you can apply a scratch coat followed by a final smooth coat. Lime wash is typically used as a final coat for plasters and composed of water, slaked lime and pigment if desired.[10]
  • Important: Lime is very caustic, and therefore requires the use of protective gear when working with lime and water mixtures. The pH level can reach 12, which can damage the skin. Vinegar or lemon can be used to neutralize the lime if it comes in contact with the skin. As a precaution, it is suggested that you wear protective gear including rubber gloves, gogggles and appropriate clothing.[11]

Block Making

The raw materials used in the creation of concrete blocks typically include sand, gravel, and cement, but can vary depending on purpose and available materials. These materials are kept separate and dry until ready for pressing. They are then consolidated by using large mixing blades and adding water until the desired texture is reached. The mixture is then placed into a mold in a large machine that applies high levels of pressure to the mixture. Four blocks are produced at a time by the machine used in Las Malvinas. The curing process requires that the drying process is controlled so that the blocks do not dry too quickly, which would result in cracking. This is controlled through watering down the blocks several times depending on local climate.[12]

Fiber-Cretes

A fellow student and past Practivista at UNIBE shared some of his current research from making blocks with sawdust and other materials. In his experimentation he is using sawdust as a replacement for river sand. This is a potential area for experimentation in this project. His blocks were very durable and able to withstand approximately 2,900 Newtons of force.[13]

Paper-Crete

  • Papercrete is an alternative construction material that, in general, is made up of milled paper and an adhesion component like clay or cement. Since paper comes in many forms, i.e. junk mail, magazines, beer cartons, newspapers, etc., so does papercrete. While there is no definitive formula for building with papercrete, various forms of papercrete masonry have been successfully employed[14]. Paper is a common waste product and can be sourced for free, making papercrete an affordable, green masonry alternative. In Santo Domingo recycling services are not readily accessible and waste management is a visible environmental issue. The use of papercrete construction can be a paper-waste outlet for growing communities, while reducing the cost of building materials.
  • The papercrete blocks from 2012
    In the 2012 Practavistas program, the Las Malvinas group worked on building a schoolroom out of papercrete and ecoladrillo. Their process involved pulping the paper with a blender in a mix of 4 parts paper to 1/8 part lime and 8 parts water, then letting the mixture dry. This was then mixed with concrete and water and the slurry was pressed into blocks. The ratios for these blocks were 1 part paper to 1 part sand and 1 part cement. [15]. In a visit to the site this summer, the papercrete wall in the schoolroom appeared to be in very good condition, better, in fact, than the ecoladrillo.
Properties
  • In terms of insulation, papercrete has an R-value between 2.0 and 3.0, making it a more suitable building material than concrete for the Dominican Republic's warm climate. The R-value of concrete is about 0.08[16].
  • Papercrete can have a compressive strength of about 150 lbs per square inch, much lower than concrete but enough to support a roof load[17]. Papercrete blocks tested at this amount of pressure squished, but did not crumble.
Recipes
  • Here is a starting formula provided by LivingInPaper.com for a 200-gallon batch[18]:
    • 160 gallons (727 liters) of water
    • 60 pounds (27 kilograms) of paper
    • 1 bag or 94 pounds (43 kilograms) of Portland cement
    • 15 shovelfuls or 65 pounds (29 kilograms) of sand
  • Here is a by volume mix provided by Papercrete.com[19]:
    • 12 parts paper
    • 4-6 parts soft clay
    • 2-3 parts lime putty

Sawdust-Crete

Sawdust

Sawdust is considered a waste that is created during the manufacturing of coffins and many other products. It is a waste product that, if not added to the general waste stream is often burned. It often is not removed from the creation site, which allows it to become a hazard for fires and air quality[20].

  • BMP Association LTD is a company based out of Moscow that produces equipment for companies and experiments with different and new building materials, including sawdust concrete. They claim several benefits of using sawdust concrete:
    • Fireproof
    • Indoor humidity control
    • Frost-proof
    • Resistance to mold and fungi
    • Compatibility with various other materials and finishes
    • Much lower heat conduction than bricks: 0.08-0.17 Wt/m as opposed to 0.5-1.5 in brick.
      • According to their website, this means that it takes half as much energy to heat a home with 20cm sawdust-crete walls than with 50cm brick walls.
    • Much lower density: 400-850 kg/m3 as opposed to 1550-1950 [21]
  • Timbercrete is a company based out of Australia that specializes in bricks, pavers and finishes
Recipes
  • From an article on Scribd.com:
    • Sawdust is first mixed with minerals to resist decay, molding and rot. May somewhat mimic natural process of wood petrification.
    • 85% wood
    • 12% cement
    • 3% fly ash
    • The resulting product weighs half as much as ordinary concrete, can be pressed into blocks skin to Concrete Masonry Units and has an R-value of 18. Buildings using these blocks, known as "Faswall Forms" do not use mortar, they are instead stacked, rebar is placed between the spaces in the form and then the form is filled with concrete. [22]
  • After World War II, a man named Friberg built his home in Idaho, USA with sawdust concrete. Mother Earth News did a follow-up article on his home thirty years later. The home was found to be in excellent condition, with little sign of deterioration and excellent insulation. This mixture was found to only have one quarter to one third the strength of ordinary concrete and Friberg recommended it for indoor use.
    • By volume:
    • 1 part cement
    • 1 part diatomaceous earth
    • 3 parts sawdust
    • 3 parts shavings
    • 1 part clay
    • Clay, diatomite and cement were mixed first, then sawdust and shavings were added.
  • This recipe was found on the Digest blog and is recommended for a durable concrete.
    • 135 kg cement
    • 135 kg slaked lime
    • 600 kg sand
    • 200 kg sawdust
    • ~250 L water
    • This site claims 80 days for hardening time [23]
  • From an online book on building sauna floors:
    • 2 parts sand
    • 2 parts sawdust
    • 1 part cement
    • Cured for one month[24]
  • This recipe is used for making bat caves:
    • 4 Quarts wood chips
    • 1 Quart cement
    • Recommends only using CaCl in the water because sugars in the wood chips can keep the concrete from binding. [25]
  • The NSW Good Wood Guide offers this recipe for a sawdust-crete. This site reccomends use as a non-load bearing infill.
    • 3 parts sawdust - hardwood used for best results
    • 2 parts sand
    • 1 part cement
      • Blend the dry ingredients, first sand and sawdust then concrete.
      • Add water, only enough to hold, but not produce excess when the mixture is squeezed. [26]

Rice Hull-crete

In the community presentation with Las Malvinas rice hulls were mentioned as a potential resource for the community. A study done in India analyzed the possibility of using rice hulls in concrete blocks. In the study rice hulls were added at 0.5, 1.0 and 1.5 percent as compared to the amount of concrete added to the mixture. Although workability of the concrete decreased, other factors such as tensile strength, impact strength, displacement and energy absorption were improved significantly. Also, the blocks with rice hulls added were found to tend to crack before failure as opposed to the plain concrete blocks, which would tend to fail without much warning.[27]

Rice Hulls

Rice hulls are the protective layer surrounding the rice grain that is composed of silica and lignin[28].‎ Composting, open burning and livestock feed are some of the common ways to reduce waste of materials from the food industry[29]. Rice hulls have been used in construction because of its potential low water absorption, thermal resistance and insulative properties. These properties resist expansion and absorption, which has allowed rice hulls to be used successfully as infill for houses.[30]. Rice hulls have a water absorption of 123.7% [31].

Recipes
  • One recipe for rice hull blocks from the book "Rice"
    • 1 part cement by weight
    • 0.25 parts rice hull by weight
    • 0.35 parts water by weight [32]
    • This translates from weight to volume to approximately:
      • 6 parts rice
      • 2 parts cement
      • 1 part water

Rice Husk Ash-Crete

A study published in India's NBM Media site suggested the use of 10% by mass rice hull ash (RHA) to enhance various properties of cement. Resistance to acidic environments, compressive strength and surface moisture of cement blocks were all found to have increased with the addition of approximately 10% RHA. This also counts for use in mortar. Concrete blocks fared best with 12.5% RHA[33]. A Brazilian study concurred, finding that 10% RHA decreased total water absorption by up to 38%. Compressive strength increased, with mixtures both of 5% and 10% RHA (5% having a greater compressive strength). These blocks were aged up to 28 days[34]. The Center for Vocational Building Technology suggests using 30% rice hull ash in a cement mixture, and that the quality of performance is on par with 100% cement [35].

Rice Husk Ash (RHA)

RHA is produced by the burning of rice husks and is a common by-product of rice production[36]. In Las Malvinas, there is a nearby producer of rice husk and also rice husk ash as a by-product of their activities. Rice husk ash is composed of 90-95% silicon dioxide and can improve the workability, stability, reduce cracking and reduce plastic shrinkage of cement[37]. It is also of interest for this project particularly for its ability to decrease the amount of cement needed.

Recipe
  • 10% rice hull ash by mass added to cement or mortar.
  • 12.5% by mass added for concrete.[38]

Mortar

Mortar can be made with cement, sand, and sawdust, although these mixes are known to be weaker than "traditional" mortars[39]. In a test of cement/sawdust mixtures, over 10% sawdust in a mortar decreased the compressive strength by more than half. Mixtures of 10% and less still had a significant effect upon the compressive strength of the mortar[40]. It is possible to utilize a lime-cement mortar, which consists of 1 part lime to 3 parts sand. Another option is to utilize compo-mortar which consists of 1 part cement, 1 part lime and 6 parts sand. [41]

Finishes

  • The finish used in the 2012 schoolroom project was composed of:
    • 4 parts water
    • 1/4 part lime
    • 4 parts sawdust
    • 3 parts sand
    • 2 parts cement.[42]
    • In visiting the schoolroom this year, some of the walls were cracking, which could have been partially from the mixture for the finish, so this year's project will likely want to revise this mixture if it is the one chosen.

Roofing Materials

The roof of the Botica Popular will likely be of zinc sheets, similar to the 2012 schoolhouse project.

Sketch

This sketch was created to portray the dimensions and general layout of the Botica Popular. It includes the cistern, which the Botica Popular partially overlaps.

Botica sketch.png

References

Template:Reflist

Contributors

Holly Johnston, Elisabeth de Jong, Johnny Lococo, Judit Germán,

  1. http://www.presidencia.gob.do/comunicados/promesecal-aplicaci%C3%B3n-decreto-608-12-permite-ahorro-de-1320-millones-de-pesos
  2. http://www.greenspec.co.uk/embodied-energy.php
  3. http://www.dominicanaonline.org/portal/espanol/cpo_clima.asp
  4. http://www.dominicanaonline.org/portal/espanol/cpo_clima.asp
  5. http://www.dominicanaonline.org/portal/espanol/cpo_clima1.asp
  6. http://www.dominicanaonline.org/portal/espanol/cpo_clima3.asp
  7. Sr. Vasquez, owner of block-making company
  8. Uhler, Frank G. "Mortar and cement compositions." U.S. Patent No. 2,437,842. 16 Mar. 1948. http://www.google.com.do/patents/US2437842?printsec=abstract&dq=making+lime+plaster#v=onepage&q=making%20lime%20plaster&f=false
  9. Case, Gerald Otley. "Plaster and the like." U.S. Patent No. 2,016,986. 8 Oct. 1935. http://www.google.com.do/patents/US2016986?dq=making+lime+plaster
  10. http://www.traditionalandsustainable.com/TSB/Lime_Putty_files/Lime_Use_Guide-2.pdf
  11. http://www.traditionalandsustainable.com/TSB/Lime_Putty_files/Lime_Use_Guide-2.pdf
  12. Koski, John A. "How Concrete Block Are Made." Masonry Construction, October 1992, pp.374-377. http://www.madehow.com/Volume-3/Concrete-Block.html#ixzz2WDovZcR6
  13. interview with Jacob, 6/7/13, interviewed by: Holly Johnston, John Lococo, Elisabeth de Jong
  14. http://livinginpaper.com/
  15. http://www.appropedia.org/Las_Malvinas_ecoladrillo_schoolroom_2012#Papercrete
  16. http://www.masongreenstar.com/sites/default/files/Research_Report_Thermal_17p.pdf
  17. http://www.livinginpaper.com/tests.htm
  18. http://www.livinginpaper.com/mixes.htm
  19. http://www.papercrete.com/papercrete.html
  20. Davis, Gray, et al. "Feasibility Study on the Expanded Use of Agricultural and Forest Waste in Commercial Products."
  21. http://www.bmp.su/
  22. http://www.scribd.com/doc/40318020/New-Chips-on-the-Block . 1/1/00. Ken Roseboro.
  23. http://digest-1.blogspot.com/2011/05/how-to-make-wall-with-good.html
  24. Sauna: a Complete Guide to the Construction, Use and Benefits of the Finnish Bath by Rob Roy. 2004. Chelsea Group Publishing
  25. http://cms.zwergfledermaus.de/wp-content/uploads/2011/04/BatCaves-recipe.pdf
  26. http://www.rainforestinfo.org.au/good_wood/sawment.htm . Sawdust sand and Cement. By Russell Andrews. The NSW Good Wood Guide
  27. Sivaraja, M., S. Kandasamy. Potential Reuse of Waste Rice husk as Fibre Components in Concrete. Vol 12. No 2. 211. Asian Journal of Civil Engineering. pp 205-217.
  28. Olivier, Paul A. "The rice hull house." The Last Straw 25 (2010). naturalhomes.org/img/ricehullhouse.pdf
  29. Davis, Gray, et al. "Feasibility Study on the Expanded Use of Agricultural and Forest Waste in Commercial Products."
  30. esrla.com/pdf/ricehullhouse.pdf
  31. Sivaraja, M., S. Kandasamy. Potential Reuse of Waste Rice husk as Fibre Components in Concrete. Vol 12. No 2. 211. Asian Journal of Civil Engineering. pp 205-217.
  32. Rice, Vol 2: Utilization. Editor:Bor S. Luh
  33. Mishra, Sudisht. Dr. SV Deodhar. Effect of Rice Husk Ash on Cement Mortar and Concrete NBM Media. October, 2010. http://www.nbmcw.com/articles/concrete/18708-effect-of-rice-husk-ash-on-cement-mortar-and-concrete.html
  34. Tashima, Mauro M. Carlos A R Da Silva. Jorge L Akasaki. Michele Beniti Barbosa. The Possibility of Adding the Rice Husk Ash (RHA) to the Concrete. http://congress.cimne.upc.es/rilem04/admin/files/filepaper/p282.pdf
  35. http://cvbt-web.org/?q=Rice-Husk-Ash-Cement
  36. Tashima, Mauro M. Carlos A R Da Silva. Jorge L Akasaki. Michele Beniti Barbosa. The Possibility of Adding the Rice Husk Ash (RHA) to the Concrete. http://congress.cimne.upc.es/rilem04/admin/files/filepaper/p282.pdf
  37. Mishra, Sudisht. Dr. SV Deodhar. Effect of Rice Husk Ash on Cement Mortar and Concrete NBM Media. October, 2010. http://www.nbmcw.com/articles/concrete/18708-effect-of-rice-husk-ash-on-cement-mortar-and-concrete.html
  38. Mishra, Sudisht. Dr. SV Deodhar. Effect of Rice Husk Ash on Cement Mortar and Concrete NBM Media. October, 2010. http://www.nbmcw.com/articles/concrete/18708-effect-of-rice-husk-ash-on-cement-mortar-and-concrete.html
  39. Elpel, Thomas J. Living Homes, Integrated Design and Construction 5th ed. p 114. Google Books.
  40. Bdeir, Layla Muhsan Hasan. Study Some Mechanical Properties of Mortar with Sawdust as a Partially Replacement of Sand." Anbar Journal for Engineering Sciences. 3/4/12. http://www.iasj.net/iasj?func=fulltext&aId=41133
  41. http://www.fao.org/docrep/s1250e/s1250e09.htm
  42. http://www.appropedia.org/Las_Malvinas_ecoladrillo_schoolroom_2012
Cookies help us deliver our services. By using our services, you agree to our use of cookies.