Final Report of Building Material Research in Batticaloa|Qi Guo|B.Arch2017|
Updates from my last post. I finally finished the fabrication of the new compressed earth block machine mould, which can produce interlocking blocks.
loaded the soil and started testing.
Becuase the block was still fragile at this stage, I made a pair of wooden aid for taking the fresh blocks out of the machine without damaging them.
Getting ready for constructing a demonstration wall.
As I mentioned in my previous post, the goal of the interlocking block is to construct a clean and neat wall, which does not expose any mortar gaps or need any extra plaster or paint on the outside. Furthermore, it saves the mason’s time for leveling and aligning the bricks during the constructing process.
The blocks are very easy to handle, and all the mortar is concealed inside the blocks.
As you can tell, the wall that is constructed by the new interlocking blocks looks much neater and tidier compared to the wall that is made by local fire-brick or the normal compressed earth block.
After finishing the interlocking block experiment, I just realized how little time I had left. Therefore, I started to set up an exhibition space for storing and demonstrating all the samples and materials I used for my experiments. All the samples are carefully labeled with detailed information so that if any student or teacher wants to repeat some of my experiments or make improvements, this space would be very helpful and convenient for them to start from where I left.
In the meantime, I also made a booklet that documents all my analyses, detailed drawings, experiments, instructions, and design process. I’m sure that with this document and the samples in the exhibition space, anyone can understand what I have done and what is the goal and value of this research.
I do understand that two months is too short for a research like this. I could not say that I finish this project. Instead, I would say that I completed the phase #1 of this project by setting up a resourceful foundation on such topic in Batticaloa. This foundation would definitely help me or anyone who has a similar interest in the future to develop this project.
You can view the digital booklet online:
Read more about my project here:
Learning from the local villages|Batticaloa St.John Vocational Training Center|Qi Guo, B.Arch 2017
Material Experiments-Qi Guo, BArch 2017
Updates From Batticaloa|Material Experiments|Qi Guo|B.Arch2017|
Updates From Batticaloa|Material Experiments|Qi Guo|B.Arch2017|
ROOF TILE
Afer a week of curing in the water, the first batch of the roof tiles was ready for testing. First, we checked the surface. We got rid of those with holes and cracks on the surfaces. These holes were caused by the improper handling during the vibration process. These products were not good for roofing.
We brought the smooth and intact one to the further tests.
We weighted each product and compared each weight to the weight of the common clay tile.
A common clay tile is around 2.75 kg. Since out tile is 30% larger than the clay one. We need to control our tile under 3.6 kg in order to beat the clay tile. The picture below is the one with rice husk ash in the cement mixture. It greatly reduced the weight of the tile to 3.25 kg, which is 10% lighter than the clay tile with the same size as our tile.
Strength Test
For testing the ultimate tensile strength, we loaded 10 kg sand each time into a bag on the top of the testing machine.
Most of the tiles we tested can withstand 80kg, which was over the strength requirement (60kg) for local housing roof tile.
The tile broke when the load surpassed its ultimate tensile strength. We examined the cracks and broken pieces carefully to study their properties.
One of the benefits of having fiber reinforcement in the tile is that the fiber material binds the tile together when cracks appear.
Some tiles broke easily, and we found that it was contaminated by other materials during the mixing process.
BRICK
For the brick, we also made some progress in the past a few weeks. Even we have not yet tested those bricks, which require a long curing time (one month). The bricks looked very neat and felt very sturdy in hands. I have confidence that the coming strength tests will have some pleasing outcomes. In the meantime, I also thought about how to improve the brick wall construction. I want the brick wall to be clean and neat without exposing any mortar. I also want to minimize the use of mortar in the joints to bring down the cost. So I looked into the design of interlocking brick.
Early sketches
The mould of the machine determines the shape of the bricks. By altering the mould, we could get a variety of shapes according to our needs. In STVTC, I found another compressed brick machine that loses its mould. I decided to design a new mould for it.
I designed a mould that could make bricks with dovetail joint on the short sides so that no mortar is needed to join the bricks in the horizontal direction. The bottom of the brick has a channel to fit the upper extruding parts. Only minimal amount of mortar is needed to fill the gap between the extrusions and the channel. It also saves the masons a lot of time in leveling and aligning the bricks. The wall would look absolutely clean and straight with this kind of brick construction.
(The drawings and all designs of machine mould are the property of St.John’s Vocational Training Center and Qi Guo. You may not reproduce, retransmit, distribute, disseminate, sell, modify, publish, broadcast or circulate the content received through this site to anyone, including but not limited to others in the same organization without the express prior written consent of Qi Guo.)
In order to minimize the production cost, we visited the local junkyard shop to search for used materials that we need for the mould.
We got a few 10mm and 12mm used industry steel plates. However, we encountered an issue. The manufacture of the mould required the work of milling machine and lathe machine, which supposed to be provided by machinery workshop at STVTC. But because of some financial problems, STVTC closed down their machinery section a few years ago. We had to find another way. Finally, we decided to cooperate with the students and teachers from the Eastern Technical Institute (ETI), which is another vocational training center in the local district. A lot of the faculty at STVTC received their training from ETI.
ETI has larger machinery workshop and better facilities.
Oxy-fuel cutting to cut the steel plate in approximate sizes.
Milling machine for cutting exact and complicated shapes.
Further finishing by hands.
One bottom Plate of the mould in progress.
It will take about ten days to finish the mould. I will update the result when we finish. Although the mould could be done easily and accurately with modern CNC machine and laser cutter in the capital city Colombo, I decided to do it locally with the less developed tools and machines. Such decision was made based on the core idea of my research, which is to work with the limitations of the local resources. Also by giving such task to the local people, it would help them gaining more experience, which could be helpful in producing other modifications in the future.
Read more about my project here:
Material Experiments-Qi Guo, BArch 2017
Learning from the local villages|Batticaloa St.John Vocational Training Center|Qi Guo, B.Arch 2017
Final Report of Building Material Research in Batticaloa|Qi Guo|B.Arch2017|
Material Experiments-Qi Guo, BArch 2017
After my previous field trips to the local villages and workshops, I found a lot of issues about the local housing materials and construction techniques. One particular issue that drew my attention was the local fired-brick. Traditional fired bricks have a lot of drawbacks. They are weak and dingy, and the firing process causes air pollution as well. It is a technique that is banned in a lot of other countries. But due to its low cost, it is still the most common material for the housing construction here.
However, due to the low precision and unevenness of the fired bricks, masons have to add an excessive amount of mortar (a mixture of cement and sand) to level them up and bind them together. The outcome is that the walls usually look crude and crappy with the excessive mortar outside, so the villagers have to apply another layer of plaster (also contains cement) to give the wall a finishing looking. However, plaster not only costs a lot but also seals the bricks so that the walls don’t breathe. Living in a plastered house feels hotter compared to a unplastered one. Another issue I found was the trend of using concrete blocks in the local housing projects. People want a concrete building because it is more durable, and it feels “western” and “modern-looking” to them. However, most of the local houses are only one-story height. There is no need for such strength. Besides, cement is imported and very costly. It does not work quite well with the climate and culture here unless we alter it with other local materials.
The importance of creating a housing scheme that is cost efficient and culturally and environmentally suitable is very urgent.
In St.John’s vocational training center, I found three compressed earth block machines in the storage room. Because of the poor maintenance, all the machines were broken down and they were left in the storage for many years. Compressed earth block (CEB) has a lot of advantages compare to the fired bricks. CEB is strong and neat, and there is no need for fire curing. The main ingredient for CEB is soil, which is locally available and it is also biodegradable. By adding stabilizer into the soil, CEB can also be water-proof. In this case, no plaster is needed after finishing. So I decided to fix one of the machines to start my experiments with CEB.
I asked the automobile students and teacher to gather parts from different machines to reassemble a workable one.
Now the machine is back to work!
My goal for the following experiments is to test the strength and other potentials of the CEB by adding different natural resources as fibers, aggregates, and stabilizers into the soil in order to decrease the cement stabilizer and bring down the cost.
Coir Fiber
Coir fiber is a natural fiber extracted from the husk of the coconut. It is a cheap and common material in local for bedding mattress, sitting pads, ropes, and other handicrafts. Students and I decided to add it into the soil.
The first one we made was a failure because we added too much water. But we will cure it anyway to test the strength.
Palmyra Palm Fiber
Palmyra palm is a common and valuable resource in Batticaloa. People use everything on the tree for making products. The wood can be used in roof structure; the leaves can be weaved into baskets and fences; the seeds can be made into drinks…
the stems of palmyra palm have very rich fibers that are extremely strong. I want to extract them and add into the soil.
At first, I tried to extract the fibers by hands and just realized how hard it was. A school staff came to us and showed us a local technique of doing this. He simply placed the stem on a flat surface and hit it with a rod…
whala! local wisdom.
And then we placed the fibers under the sun for one day until they totally dry.
moisten the fibers with water again for preparing the soil
We carefully sprinkled the water onto the soil
Beautiful and neat bricks with fiber texture.
The students were surprised at the outcomes. Even though they were very familiar with the palmyra palm, they never thought about using it in the construction materials.
Cow Dung
Cow dung is one of the most commonly found wastes in the local villages. Villagers use it as fertilizer for their farms. From my previous field trip, I was surprised at its use for natural plaster on the mud house to get a polishing looking and also repel the insects.
Cow dung is very hard when it is dry, but when you break it down, you can find all the fine fibers that are not yet digested by the cow. Cow dung is a natural “clay” and the fibers inside can reinforce its strength.
The villagers today are against the use of this material in their houses because it is a humble material, and the families that use this material are poor and backward to them. I think my purpose is to teach the students to never underestimate any materials that just look humble because design can transform materials for a better value.
Afterall, can you tell if these nice-looking bricks were made out of cow dung if I did not tell you?
Soil 
Different soils have different qualities and characters due to the percentage of gravels, sands, silt and clay they contain. Gravels and sands enhance the strength of the bricks but they have very low cohesion. Clay does not have strength but it is a natural binder to bind all the particles in the soil. In order to make a durable compressed earth block, we need to be very careful about the selection of the soils.
Choosing the right soil is significance to the quality of the bricks. Too sandy or too clayey soils may cause weak and cracked bricks. We experimented a lot with different kinds of soils, and also leaned from so many mistakes and failure.
Soils also have varying colors due to the minerals they contain. The locally-made compressed earth blocks also can reflect the local geographic context.
Soil jar test
The simple way of testing the percentages of gravel, sand, silt and clay in the soil is to precipitate the soil in water. The heavy gravels and sand would fall to the bottom of the jar. Silt and clay would sit on the top.
Once we know the components of the soil, we could alter its components by adding more sand or gravels for our own purposes.
Only with the right kinds of soils, we could make the strong and neat blocks.
In the meantime, I also started the tile experiments with the students last week. Tile is a big cost in the housing construction in the local community. One clay tile costs Rs 32 (around $0.25), which is about four times the cost of a fired brick. The clay tile is made by the high-precision machine, therefore,it is not friendly to the villagers with lower skills.
In the VTC’s storage room, I also found a broken vibration table for making micro cement tile, which was larger, cheaper and much stronger than the common clay tile. It also requires very low technology. However, the disadvantages are the weight and the heat. So my goal is to reduce the amount of cement in the tile to bring down both the strength (we don’t need that much in tile) and the cost.
Students and teacher from automobile section helped me to fix the vibration table.
Burned Rice Husk Ash
Burned rice husk ash is a waste product that is produced by the fired-brick workshop. I collected some samples from my previous field trip. Because I found this material has surprisingly fine texture and light weight. I tried to add it into the tiles to see how much weight it could reduce without dramatically decrease the strength.
demolding and water curing
Wood Dust
I found a lot of wasted wood dust in the carpenter section at VTC. Wood dust has relatively larger texture but it also very light. So I decided to give it a try as well.
The bricks and the tiles are still in the process of curing. I will update the strength test in the coming weeks. For the next month, my plan is to continue the experiments and also working on the housing scheme for the low-income family house.
Read more about my project here:
Updates From Batticaloa|Material Experiments|Qi Guo|B.Arch2017|
Learning from the local villages|Batticaloa St.John Vocational Training Center|Qi Guo, B.Arch 2017
Final Report of Building Material Research in Batticaloa|Qi Guo|B.Arch2017|
Learning from the local villages|Batticaloa St.John Vocational Training Center|Qi Guo, B.Arch 2017
For the first two weeks, I went on several field trips with some students and teachers from SJVTC (St.John’s Vocational Training Center). The goal of these trips was trying to understand the local materials and resources and related industries. Furthermore, I also tried to see and learn from the local traditions in order to design something more culturally and environmentally suitable for the local community . We went to a surrounding village called Kadkkamunai to visit a local brick workshop and to see some local housing construction techniques.
The brick making workshop normally locates at the site where has clayey soil. A few workers first remove the top soil and then dig out the sub-soil from the ground.
A worker added water into the soil to get the right moisture for the clay mixing.
Meanwhile, a worker started to make bricks out of the wet clay with the wooden mode.
The bricks then would be stacked and stored for drying under the sun for three days to remove the water and gain extra strength.
And then the bricks would be fired for another two days to achieve maximum strength.
A hand-made fired brick costs around 9 rupees (0.07usd) in the local village, including the transportation cost.
Different gravel sizes of the soil.
Taking some sample soil back for further testing.
In the village, people used to have the tradition of building houses with only mud and wood branches. Such house is fairly strong and cheap, and it works along with Sri Lanka’s hot and humid climate due to the soil’s nature. The mud house keeps the heat out in summer and maintains the heat inside in winter. But the villagers stop making such houses because they believe mud and branch are the symbols of poverty.
Here was an abandoned shelter in the local village. This shelter was entirely constructed by clay and tree branches.
These shelters could last for a very long period of time with careful maintenance.
A local woman showed us how to polish the mud floor with cow dung, a cheap and accessible material in the local village. The floor became shiny and waterproof by applying the cow dung on its surface.
The coconut tree is a very common tree in Sri Lanka. We also paid a visit to a workshop that makes products out of dry coconut coir.
The workers in the workshop gave us a demonstration on how to make a rope out of coconut coir with a simple bicycle wheel.
Here are some other products that were made by these ropes.
Taking a sample back for further study.
Read more about my project here:
Material Experiments-Qi Guo, BArch 2017
Updates From Batticaloa|Material Experiments|Qi Guo|B.Arch2017|
Final Report of Building Material Research in Batticaloa|Qi Guo|B.Arch2017|
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