Lots of people fear using concrete. If it goes wrong, it can be difficult to fix, but for smaller domestic jobs it’s actually a lot easier than many people think. With this guide, we’ll go over the different ways to mix concrete so you can decide what’s best for you when attempting your DIY project.

Concrete Proportions

Concrete has 3 main ingredients. Cement, aggregate, and sand. These ingredients are mixed with water, which when dried out, binds into a solid, very hard material. Depending on what you’re using the concrete for, these can be mixed in different proportions to give you different finishes and strengths.

It’s very important to get these proportions correct. With too much sand, your concrete won’t be hard enough to withstand the test of time. However, too much aggregate and you’ll be rushing to find a way to cover it up and pretend that it isn’t there.

Mixing Methods

In a domestic setting, there are several different approaches you can take to mix your concrete. If you’re happy giving the different proportions a go, you can either do this by hand or by using a mixer. For small scale jobs, mixing by hand can be ideal as it’s easy to keep track of the consistency and see how it’s going. This can often be a good thing to do as a practice if this is your first time. For larger jobs, a concrete mixer can save you hours of time and strength mixing larger amounts of concrete together.

When it comes to domestic concrete, it’s often overlooked that there are some other options also available to you, especially for slightly larger jobs such as concrete bases for sheds, summerhouses and other garden accessories. The main differences between domestic and commercial worksites are space. Often with a commercial worksite, the work will be planned to make these processes as efficient as possible, allowing the concrete mixers to reverse right up to where they’re going. However, this doesn’t mean you can’t utilise similar methods.

Types of Concrete Mixers

There are two main different types of concrete mixer. There are ordinary concrete mixers and also volumetric concrete mixers and both of these have different uses. You’ll likely have seen ordinary concrete mixers or mini mixers driving around quite frequently. These have the advantage of being able to transport one of many different mixes of concrete. Extra ingredients can be added to the concrete at the factory in order to provide different properties such as waterproofing or extra fibres for additional strength. However, this isn’t often needed when it comes to domestic concrete.

The other type of concrete mixer is a volumetric concrete mixer. These are ideal for domestic concrete as you don’t need to worry about having too little or too much. ‘Mix as you go’ concrete mixers contain the raw ingredients needed and as you pour out the concrete will mix it straight away. They also have the added advantage over traditional concrete mixers of being able to supply multiple different mixes of concrete to the same job without having to pay the additional cost of bringing in a second load.

Concrete mixers and volumetric concrete mixers are also a great choice for people taking on DIY projects that don’t want to take the risk of getting the mix wrong. All you’ve got to worry about is where it goes with the extra guarantee of knowing that it will stand the test of time. Thank you for reading this blog post. Should you have any enquiries, feel free to call us on 07812 182778 or visit our contact page for more information.

The post How to Mix Concrete by Hand or in a Mixer first appeared on Base Concrete.

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In the former articles was explained some of the advantages to be found within these ancient  common methods of charring wood. Historically and within many cultures, there are a myriad of charring modalities. In this article you will find adapted and illustrate one of those methods using a small wood burning flash oven that can effectively provide the charring levels needed without overtly case timber that has been dried too rapidly. This leads to reversed stresses; compression stresses on the shell and tension stresses in the core. This results in unrelieved stress called case hardening.[1]) the wood items placed through it. In this article we explain how our charring station is built and how it works. Charring systems like this one have been commonly found in many cultures and this is an adapted version of several of those [2]. It is adaptable, is easy to operate and runs without the use of gas or special tools. All that is needed are some (fire) bricks and scrap wood for fuel.

Counter-intuitively, charring wood has several astonishing advantages without involving any chemicals or additional energy consumption. The idea is to sear the surface of the wood without combusting the whole piece nor damaging the interstitial aspects of the wood so it will not warp over time. Besides giving the material an interesting and unique look, the process leads to a triple protection, all without the need of repeating the process after some time has past:

fire protection – charring the surface starts a superficial carbonation of the material and thus lowers the thermal conductivity. termite and mold protection – charring wood destroys the wood’s nutritional value to insects and fungi.water protection – the enhanced carbonation gives the charred layer a waterproof resistance, as water slips on burned wood like over an oily surface.

The easiest and most popular way to char wood commonly found today is probably with a blow torch. This can work, but regrettably too often performed without the attention to detail not to stress the wood from within. It’s easy and practical,  especially for small or irregular pieces but has to be performed with caution. But when searing many big wooden pieces it is slow and uses a lot of gas. These searing modalities are not to be confused with traditional Japanese, 焼杉 (Yakisugi) which is often misrepresented as 焼き杉 (aka shou-sugi-ban”) [3] – us included, in our previous articles!.

Yakisugi can only be achieved with a limited range of Cypress species found on the islands of Japan[4] and is a very unique process found within several methods of crafting guilds. The most commonly seen being where three planks of wood get bound together to form a long triangle and a fire is started in the resulting tube. There are several other methods, but they are for very specific formats and within context to only yakisugi and not the charing modalities found within other cultures.This technique works well only when you have similar boards, as it’s complicated to set up when boards have different widths and lengths.

Terunobu Fujimori, Tea House, Barbican. Photo Ben Tynegate

The birth of the charring station

This contemporary oven is based on some of the principles of a rocket stove. The main idea is to create a fire within a brick tube, which will become very concentrated and strong due to the tube-generated draft-effect (for more explanation on this and general information, check our articles on rocket stoves). Just over the burning material, where the fire is very strong, there will be small slots on the opposing sides of the tunnel. The wood, which needs to be seared, can be passed easily through the fire and thus be charred fast and safely.

After this oven was created with commonly available materials which enables us to char planks and boards of different sizes in an effective manner. This oven also allows the operator safety by lowering the risk of burning their hands, while also providing more control of searing the wood and less waste of fuels which is then more environmentally friendly.

How does the charring station work

Author: Melana Jäckels

1 – The main part is a L-shaped tunnel. On the bottom it has an opening on the side, where the air goes in and it flows all the way through the tunnel up to the upper opening. 

2 – Right after the curve, the fireplace is based on a second layer. Its bottom has two small gaps for the air to pass and to allow the finer ash to fall.

3 – It is important to have a tunnel that is at least 5 cm wider than the boards you plan to char. If a board fills the whole wide of the tunnel it stops the draft and decreases the fire.

4 – On the same level as the fire is also the stair-like firewood intake. The fire is started and fed from here. It’s important to have a brick to close the firewood intake so it does not disturb the air draft in the moments no wood is inserted.

5 – In the chimney, right above the fire, there are two vertical slots on opposing sides to insert the wood you want to char.

6 – Above the inserting slots the chimney narrows slowly. This is important to not happen in a sudden step, as it otherwise will decrease the draft and create a lot of smoke coming out of every small gap.

Building your own charring station

For our charring station we used 12 big bricks (ca. 29x18x9), around 70 medium-sized, red bricks (ca. 23x10x7) and 5 fireproof bricks (22x10x2). Depending on what is available, numbers and materials might be adjusted. Before starting the building process, it is important to choose a big outside space, which is not too windy and has a relatively leveled ground, with enough space on each side of the station to pass the board through.

Step by step:

First, we made a fire-resistant base which is leveled and flat. For this we used the big bricks

Afterwards we started to build a tunnel for the air intake with dimensions of 90 to 25cm. It is important that it is stable and possible to close with removable bricks on the sides

We covered the tunnel with the red bricks and left two gaps of about 1,5 cm each as seen in the picture. 

The fireplace gets covered with fireproof bricks and the next line of bricks is put on all sides

To protect the walls, we also placed fireproof bricks around the fireplace


The next step is to build the J-shaped intake with steps made of bricks, towards the fireplace. It is important to make sure its height will match up with the next row of bricks


Now it is time to create the slots where the to be charred boards will be inserted. For that we put two bricks flat across from each other. This  station works  well for boards with a maximum width of 16 cm. If you plan to use a roller stand, make sure the height of your slots measured from the ground is adapted to the height of the roller stand)


Above the slots we continued building the chimney in the original diameter for a few more rows, but then we start to become narrower by changing the order of the bricks

In this timelapse video you can see how we built up the station in 10 seconds!

How to use the Charring Station

Before starting, make sure to have the right equipment (fire resistant gloves, a mask, a bucket of water / sand, and a fire extinguisher) and enough material to burn! If you want to char a big quantity of wood it is also quite handy to have rolling stands.

Starting the fire works best when you build a little teepee out of dry kidlings and put some sawdust on it, light up the tip of a rolled paper (A4 is enough), and move it slowly into the directions of the teepee. Besides you can put another burning paper over the chimney, to facilitate the draft-effect. 

To avoid unnecessary interruptions, it is important to have a constant refilling of firewood. As soon as the fire burns strongly, the opening of the firewood intake can be closed and the boards can be inserted through the slots. Inside, the strong and concentrated fire will char the surface of the wood from below and the sides. The boards should be pushed through the fire in small steps to have a satisfying and regular result. After the first part of a board is charred, it can be taken out and pushed upturned through the fire again until both sides are completely charred. If the results are not satisfying, the pace should be adapted. Depending on the size, form and species of the wood it will take its respective time to finish one piece.

Once the board is charred it should be brushed with a metal brush and oiled. As the charring process dries the wood very rapidly, depending on its nature it might have a tendency to crack. The linseed oil will nurture the wood and compensate for this effect. For more information on this see our article on Natural Wood Protection.

Conclusion

We are using this method for a while now and we are super satisfied with the results. Not only we save time but also we are more independent of gas. The work with the charring station is safe and convenient. The station is easily adaptable and can be modified to different dimensions. We are looking forward to using the station in the future and improving it further. 

Check our YouTube video for a step-by-step tutorial how to build up your own station!

We would like to sincerely thank Jay C. White Cloud for his time, valuable input and collaboration on this research.

Sources

[1] Wikipedia “Wood drying”, [Online] available at https://en.wikipedia.org/wiki/Wood_drying (Last accessed in July 2020) 

[2] Jay C. White Cloud [Tosa Tomo Designs] https://about.me/tosatomo

[3] [4] Nakomoforestry “Yakisugi” Or “Shou Sugi Ban”? Learn What You Should Call It, And Why”, [Online] available at https://nakamotoforestry.com/yakisugi-or-shou-sugi-ban-learn-what-you-should-call-it-and-why (Last accessed in July 2020) 

Picture: Terunobu Fujimori, Tea House, Barbican. Photo Ben Tynegate [Online] available at https://www.ben-tynegate.com/tea-house (Last accessed in July 2020) 

The post Charring Station first appeared on Critical Concrete.
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DISCLAIMER

[This article shows the development of the first step of a new prototype experimented in Critical Concrete. During the conception of the green roof, the structure was checked by a civil engineer who also advised us in the development of our wildest prototypes.]

Check out the video to see how we experimented with scrap tyres and compressed earth&gravel for a low-impact and concrete free building! 

Introduction 

In the progress of developing our green roof prototype we have been confronted with foundations in different ways. Seeking for alternatives it turned out that the old granite walls of the building, once reinforced by wooden beams, would be strong enough to carry the load of the new roof. You can read all about the refurbishment and reinforcing of the walls for the roof in our previous articles (walls-refurbishment 1.0, walls-refurbishment 1.1, how to build a stone wall).

The size of the new roof however, stretches out further than the fully loadable walls. For that reason, part of the roof needs a different kind of foundation.

Section of the green roof highlighting the parts supported by tyre foundations

Our Research

Throughout our research for alternatives to concrete, we stumbled over the tyre foundation. For us, it was very interesting since it is a low-tech solution which is composed only of scrap tyres filled with compressed gravel. Both components are easily accessible almost everywhere in the world.

Indeed, when tyres worn out, they become a waste which is not easy to handle. Recently, more processes that aim at recycling have been developed from which rubber, steel and textile fibers are obtained. Another solution is to reuse the tyres directly in a different context, thus avoiding more energy consumption for the transformation of the product.

Pile of trashed tyres

Worn out tyre reused in a new contextScrap tyres have already been tested in various cases in the construction field, for example to make the roadbed of the streets and referred to as mechanical concrete, a method widely used in the USA. One of the most known cases is the Earthship Biotecture concept autonomous houses developed by architect Michael Reynolds, in which earth-rammed automobile tyres are used for building the main retaining wall of the house. This technique is presented as the most appropriate method for its strength, economy and low need of technical skills.

Pictures by mechanicalconcrete.com (pictures on the left) and by earthship_biotecture (licensed under CC BY-NC-ND 2.0) (picture on the right)

The flexibility of the tyre can also offer durable protection in a seismic area. These foundations can indeed reduce the effect of seismic vibrations on the building on top of them and it can be used in every stable soil, even clay soil (for more information click here). Yet we couldn’t find any applications that fits exactly our needs. Many cases used the tyres to build walls, or wall-like foundations where the structure was resting without anchoring. Other examples used conventional concrete to fix some kind of anchoring sockets. As far as we know, our case, a structure with several punctual load bearing columns, has not been well documented yet.

Interested in using this technology in your project?

Critical Studio can help!

Learn More!

Our Approach

In our particular case, we designed two single stepped footings for two columns of the green roof.

Section and plan of the two single stepped footings for two columns of the green roof

One part of the green roof structure lies on a massive, structurally stable granite wall built in the 19th century, and the other part will lay on the new foundation. Since it is a prototype and it is not well known how the foundations will react to the heavy load, we decided to make the new part (15m2) independent of the rest of the roof previously built (120m2). This assembly required us to insert an expansion joint which allows movement due to ground settlement or other variations, expansion or contraction of building materials. It will also assist the observation of potential changes and reduce the risk of damaging the whole roof in the worst case scenario. Indeed, this technique has been used in England for at least 15 years. Research and experiments of the Holy Trinity Church Tulse Hill showed that they tyre stacks will hold a minimum of 1000 kN/m2 of load with no detected movement on the expansion but a compressive variation of only 3mm (to watch the video click here). The IUT of Grenoble made tests of loading tyre foundations from the Flexagone office: They applied the weight of pressure of 72 tons on the foundation, without any damage or detectable movement (for more information click here).

Additionally we consulted several engineers to check our structural conceptions. As we explained in former articles, the heavy loads on the roof – composed of the drainage layer, earth and plants – impacts the renovation process by its load of 600 kg/m2– 5.88kN/m2, including the dynamic load. Based on this information and our needs, we developed the concept of single stepped footings for columns. We calculated that each pillar should carry about 2400kg approximately. The foundation includes a socket which joins it with the wooden column.

Section of the Tyre Foundation

This connection is especially important while setting up the tyre and aligning the structure. Once the roof is finished, its own weight will hold its place. Below the foundation is a metal plate. On one hand, it distributes the forces on the soil and on the other hand it connects the foundation to the holding socket of the column. On top of the metal plate lay the tyres. We chose two tyres to make the foundation strong enough for the load. One truck tyre (95cm ø) and a smaller car tyre (65cm ø). The holding socket for the column is layed on the upper tyre and connected to the foundation through threaded rods which are welded to the base plate. The socket itself also holds the column in the right position.

Our workexplained step-by-step

This guide is an overview of every step we took in building our prototype of the tyre foundation. Since it was our first attempt, not all of our processes are optimized and need further development. However, this should serve as an inspiration for anyone with a similar situation and is open for discussion and improvement.

Beforehand a list of tools we used
in the progress:

welding machine,crowbar,grinder,hammer,wheelbarrow,bench drill,shovel,cutter.

Throughout each phase, we remind you that it’s important to protect yourself using appropriate safety equipment.

For this, you will need:

helmets,protective goggles,appropriate protective gloves,security shoes,reusable dust masks.

Preparation of the ground

The first and most important step before starting any foundation is the analysis of the ground. The soil has to have a sufficient bearing capacity. If the soil is not suitable there are different possibilities like reinforcing the soil, digging deeper, or adapting the foundation type to a wider tyre for example. In our case, we needed to dig until +/- 70 cm under the floor level to find a proper soil. We decided to put a layer of 5 cm of compressed gravel, frequently used under footings to have a correct level.

Estimated time: 6 to 8 hours per pit,
depending on the toughness of the ground

Leveling the ground of the pit

The base metal plate

The metal plate is the base of the foundation and serves as a solid surface for the tyres. We chose a thickness of 2 cm. To have the plate and also the column connected to the foundation we welded 4 threaded rods to the plate. The socket will be attached to these rods later on. Before putting the plate in the pit we put a breathable and waterproof membrane supposed to protect the plate from humidity in the ground. An EPDM membrane might have been a more suitable choice to increase the durability of the protection. We tried to wrap the plate as well as possible. Additionally, we painted the base plate and especially the weld joints with anti-corrosive paint. We still don’t know how this will react with the time, neither if it is going to be efficient enough to protect the welds. Our main objective is to take all the necessary precautions to avoid that water eventually permeates and settles at the bottom of the foundation. In our next tyre foundation build, we would consider drilling some holes in the metal plate to allow for the draining of water infiltration. The use of this metal plate was advised by our engineer to level the ground on which the foundation itself would set, but we didn’t find any other project using a similar precaution. It was also helpful for us to link the column to the foundation on a robust way.

Metal plate wrapped with membrane

Estimated time: 2 to 6 hours,
depending on accessible tools to cut the plate on the good dimensions

Metal plate on the ground of the pit

Preparation of the columns

The columns we used are made out of two 12×24 cm construction plywood beams. To join the two pieces we glued and screwed them together. The section is therefore 24×24 cm. To protect the wood from fire, water and pests we applied a layer of wood ash on the tyre, as well as protected the wooden column with a layer of borax, known as a protection against mold and repellent against insects. For a specific protection to prevent a specific termite attack, we paint the column with a mix of essential orange oil (5%) and linseed oil (95%). We will soon dedicate a detailed article to wood protection from fire, water and pests.

Estimated time: 2 hours.

Preparation of the socket

We used a steel socket to fix the column with the foundation. The socket is connected to the foundation with four threaded rods. It is fundamental to align properly the rods after putting the base plate, so that the columns would be aligned to each other. We used a wooden guide to secure the rods’ position while filling the tires. This guide is composed of two pieces that represent the two plates, with the holes for the threaded rods, and a long bar that helps to maintain them aligned and in place.

Metal plate on the ground of the pit

Estimated time: 4 to 6 hours,
depending on accessible tools to cut the steel and drill the holes.

Checking the alignment

Filling of the tyres

In its rawest form, the tyres can only be filled with earth. Lots of case studies for earth filled tyre foundations are in relatively dry climates where the temperature doesn’t go below 0°C. It is preferable to use an other sub-grade as gravel or other material to encourage drainage and allow for water expansion, and then avoiding some major instability in the ground caused by frost. We decided to choose gravel made of local accessible granite, from the North of Portugal. We had the choice of three sizes of gravel. After some discussions with our engineer, we decided to order the smallest to have better cohesion. We also added some sand to create a mix with better bonding and leave no empty space between the gravel. We used the ratio of two parts gravel to one part of sand (2:1). The mix in the tyres has to be then as compressed as possible. At first, the tyre can be filled with a shovel and by hands. When it is not possible to get any more of the mix in, a crowbar and a piece of wood can be used to open the tyre (see how they did at the Holy Trinity Church Tulse Hill). Once held open, a second person can continue to fill up the space with the mix. A piece of wood can be used to shove the mix in as deep as possible and a hammer to compress it. This needs to be done until the tyre is inflated and no more mix can be added. The foundation is now ready for the socket.

Estimated time: 6 hours for two people to fill the 2 tyres for one foundation
(a truck and a car tyre).

Installation of the socket

The steel socket which is holding the column is made out of three pieces of steel. The objective is to obtain a socket that correctly holds the column. We thought about different forms and finally settled with a “U”-form, that could maintain the feet of the columns and be correctly fixed to the lower part of the foundation.

Base plate

The first part being the base plate (30x30cm), which has four holes to be fixed with the threaded rods of the foundation. The holes of the plate have to line up with the position of the threaded rods and should be 1mm bigger than the diameter of the rods to facilitate their insertion. Our rods were 12mm diameter. The second part being the two steel brackets (15x20cm), which are welded to the plate and hold the column with two horizontal threaded rods. The individual steps of this process are explained below.

(1) The holes in both of the brackets, which should be shifted, can be drilled and should be at least 2-3mm bigger than the rods.

(2) Afterward, the first bracket can be welded on the base plate.

(3) The piece, that results from this step can be used to mark the position of the holes on the wood of the column. For this, half of the steel socket can just be laid on the column.

Image

(4) It might be necessary to cut a little edge of the column so there is some space for the weld. After marking the holes, they can be drilled also 2-3mm bigger than the rod. The bigger the holes are, the more room there is to adjust and compensate for potential inaccuracies.

(5) The next step is to find the right position for the second bracket. For this, the socket can be laid on the floor, and the column can be put on it. The rods can be stuck through the holes of the first bracket, the column and the second bracket, which is not fixed yet. Also, the bolts can be put on and tightened.

Column steel base plate sketch

(6) The second bracket should now touch the base plate and there should be no gap. If it doesn’t, any holes can be drilled bigger to make it fit properly. If it fits, it can be fixed by welding on 4-5 small points. Afterward, the column can be removed. The second bracket should be in the right position and can now be welded on completely.

Estimated time: 5 hoursto install the socket: drill, weld and adjust.

Installation of the columns

Once the socket is welded together in the “U”-form and the holes are drilled, the foundation is ready to receive the columns which have a section of 24×24 cm.Having an even level foundation is crucial and is something to pay extra attention to, during all the process. First, we used the spirit level to check the level of the lower plate, to ensure that the tyre will be placed on level ground. Indeed, it is important to keep in mind that the column will apply a heavy load that needs to be properly transferred to the foundation. For the next steps, the laying of the tyres and the fixation of the socket, make sure to always keep checking the level and the alignment of each foundation.

Checking the level of the metal plate

Estimated time: 2 hours.

Preparing the columns

The retaining wall

In our case, one of the foundations is positioned under the level of the earth, in an outside environment, that forced us to find a solution for the rainwater not entering inside the workshop space. A retaining wall has been constructed to withstand lateral pressure of soil, due to earth and rainwater. There are a lot of different retaining walls, used for different situations for example the gabion retaining wall or the cantilever retaining wall.

Building the retaining wall

In our case, we built a gravity retaining wall that depends on its self-weight only to resist lateral earth pressure. Commonly, this needs to be of large proportions because it requires a significant gravity load. We constructed the wall from granite stones that we had acquired from previous deconstruction of old walls. To protect the column from water infiltration, we bonded the stones with a lime mortar mix.

Furthermore, we plan to realize a drain which prevents rainwater from entering the basement. Parallel to the retaining wall, it will collect excess water and runs it through a pipe into a sump away.

Cost and Time Comparison

Since we are using the tyre foundation instead of a concrete foundation, the comparison of cost is a crucial point. For this reason we compare only the part of the foundation which is replaceable. The socket and the column are therefore not part of the comparison, since they are the same for both versions. We already pointed out the factor of sustainability, which is our driver in this matter. But what does this mean from an economical point of view? A tyre foundation in its simplest form is only made from dirt and scrap tyres and is therefore basically free. This method is suited for retaining walls and foundations that don’t require anchoring. Our Approach of a highly stressed single step footing which includes anchoring cost approximately 125€ compared to the concrete version of approximately 28€. As the calculation shows, the major cost factor is the metal plate which is also an open question for us. Its necessity is not completely clarified wherefore we are looking for alternatives which even out differences in price and make the single step foundation an economically competitive alternative.

It is to be added that the concrete should be mixed homogeneously by a cement mixer rather than by hand, and that welding the steel reinforcement takes some time as well and electricity, and quite a few welding electrodes. In terms of time, the concrete takes at least 7 days to set sufficiently for a foundation in order to set-up the column, but is faster to make, comparatively.

Conclusion

In the process of finishing the green roof, the application of the tyre foundation has been challenging but successful so far. It is carrying the roof structure but needs further observation as to how it will react under the full load of the green roof including soil and vegetation. To be able to observe any kind of movement we installed a measuring unit that we will control regularly.

Movement measurement

Sustainable Satisfaction? 

Concrete is an extremely popular material for construction and can be found in most parts of the world. Today concrete is the primary material used for foundations because of its many positive attributes: it is strong in compression, it is flexible as it can be poured into adapted forms and sizes, it can be applied in situ, it has good fire resistant qualities. However, the production of Portland cement, an essential constituent of concrete, leads to the release of significant amounts of CO2 and other greenhouse gases. Because of limited natural resources, such as sand, and the output of greenhouse gases, concrete production is not sustainable and therefore requires alternatives in the construction field. A possibility is to use recycled materials which have low energy costs, high durability and low maintenance requirements and therefore a small impact on the environment.

The single step footing foundation represent a viable and affordable alternative method we are looking forward to developing and using in further projects.

You want to see more? Check out the video to see how we experimented with scrap tyres and compressed earth&gravel for a low-impact and concrete free building! 

Sources

[Ar. Bindu agarwal, Ar. Aanchal Sharma] “Reuse of Waste Materials: A case study of Earthships”, in: International Journal of Science, Engineering and Technology Research (IJSETR) Volume 6, Issue 10, October 2017, [Online] available at: http://ijsetr.org/wp-content/uploads/2017/10/IJSETR-VOL-6-ISSUE-10-1364-1369.pdf (Last accessed in December 2019).

[Architecture 2030] “Buildings generate nearly 40% of annual global GHG emissions”, [Online] available at architecture2030.org/buildings_problem_why/ (Last accessed in December 2019).

[Andrew, Robbie M.] “Global CO2 emissions from cement production, 1928–2018”, CICERO Center for International Climate Research, [Online] available at: https://www.earth-syst-sci-data-discuss.net/essd-2019-152/essd-2019-152.pdf (Last accessed December 2019).

[Decorex Pro] “Technology for the construction of the foundation of tires”, [Online] available at: /en.decorexpro.com/fundament/iz-pokryshek/ (Last accessed in December 2019).

[Department for Business, Innovation and Skills London] “Estimating the Amount of CO2 Emissions that the construction industry can influence”, [Online] available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/31737/10-1316-estimating-co2-emissions-supporting-low-carbon-igt-report.pdf (Last accessed in December 2019).

[Deva Racusin, Jacob; McArleton, Ace] “The Natural Building Companion: A Comprehensive Guide to Integrative Design and Construction”, 2012

[Flexagon Office] “Fondations et plots”, in: La Maison Ecologique 67 – fevrier et mars 2012, [Online] available at: http://yourtes.net/fichiers/Fondations%20et%20plots%20-%20La%20Maison%20Ecologique%2067%20-%20fevrier%20et
%20mars%202012.pdf (Last accessed in December 2019)

[Holy Trinity Tulse Hill on YouTube] “Packing Car Tyre Foundations (Car Tyre Foundations #4)”, [Online] available at: https://www.youtube.com/watch?v=0YV2TG5aypw (Last accessed in December 2019)

[Holy Trinity Tulse Hill on YouTube] “Car Tyre Foundations Plate Test”, [Online] available at: https://www.youtube.com/watch?v=K8Vlz6qNCfU (Last accessed in December 2019)

[König, H., Weissenfeld, P.] “Entretien écologique du bois”, ed. La plage, 2008.

[Lowimpact] “Why cement should never be used with natural buildings”, [Online] available at: https://www.lowimpact.org/why-cement-should-never-be-used-on-straw-bale-houses/ (Last accessed in December 2019).

[Mechanical Concrete] “Award Winning, Economical, Green, Industrial Strength, Construction Technology”, [Online] available at: http://www.mechanicalconcrete.com/ (Last accessed in December 2019]

[Miteco] “Descarbonatac fabrical”, [Online] available at: https://www.miteco.gob.es/es/calidad-y-evaluacion-ambiental/temas/sistema-espanol-de-inventario-sei-/040614-descarbonatac-fabric-cal_tcm30-429852.pdf [Last accessed in December 2019)

[Miteco] “Combust fabricamento”, [Online] available at: https://www.miteco.gob.es/es/calidad-y-evaluacion-ambiental/temas/sistema-espanol-de-inventario-sei-/030311-combust-fabric-cemento_tcm30-430164.pdf (Last accessed in December 2019)

[Naik, Tarun R.] “Sustainability of Concrete Construction”, [Online] available at: https://ascelibrary.org/doi/abs/10.1061/%28ASCE%291084-0680%282008%2913%3A2%2898%29 (Last accessed in December 2019).

[Russian Patents] “Module-type anti-seismic protective unit for buildings and structures”, [Online] available at: https://russianpatents.com/patent/225/2250308.html (Last accessed in December 2019]

[World Green Building Council] “New report: the building and construction sector can reach net zero carbon emissions by 2050”, [Online] available at: ww.worldgbc.org/news-media/WorldGBC-embodied-carbon-report-published (Last accessed in December 2019).

The post Tyre Foundations first appeared on Critical Concrete.

Let us introduce the newest addition to our production center in Porto: the compost toilet! Although human waste is a taboo subject, we will be talking about poop a lot in this article. After all, if you refuse to address a topic, how can you challenge the conventional and unsustainable systems that surround it?

One unsustainable aspect of conventional toilets is water. Most toilets in wealthy countries use potable water to flush toilets, but water is a resource that is becoming scarce amid rising global temperatures. [1] [2] Even if this were not the case, the fact we contaminate drinking water on purpose reflects a dire need to challenge this convention. Human excrement, ironically, is a valuable resource. It can be used as a source of food for bacteria. Sewage, as well as diseases linked with fecal contamination of the environment, can be eliminated when composting is adopted as a sanitation method.[9]

In our phytodepuration article, we explored one alternative method for wastewater treatment. It consists of a marsh-like condition, in which greywater and blackwater are filtered and purified using plants. Compost toilets are the inverse; they require no water and use dead plants rather than living ones. Essentially, microbes break the waste down into humus, a completely decomposed organic material. Besides feces, the other necessary ingredients for composting are straw, sawdust, dead leaves, or wood chips. These carbon-rich materials are known in the composting world as “browns,” while the nitrogen-rich feces make up “The Greens.” The balance of browns and greens is crucial to successful decomposition; a composting toilet without carbon-rich material would not result in compost and would be a health hazard. Additionally, the browns act as a cover material to expunge smells.

Across the world, different prototypes of compost toilets are being tested within diverse capacities and contexts. One such example is the project Mobile Dry Diversion Toilet in Lagos developed by FABULOUS URBAN with several partners since 2017. The project targets families in low-income communities who do not have access to domestic sanitation. This prototype separates the urine and feces into different compartments, which finally facilitates the process of composting. [4] The urea present in urine degrades into ammonia while not only has an off putting smell but also is the reason for the extermination of the bacteria that would otherwise break down the waste.[5] For further explanation, you may follow the link to the original article. Mobile Dry Diversion Toilet

Mock-up prototype being constructed to be tested for the project Mobile Dry Diversion Toilet Photo. © FABULOUS URBAN

Public acceptance, regulations, and a lack of expertise and experience in composting toilet design and operation are all obstacles to the use of composting toilets in urban environments [3].

We have been testing our system here at the Critical Concrete office.

COMPONENTS OF OUR SYSTEM INCLUDE:

a large compost pilea toilet chambera bucket within the chambera seat for the chamber


The assembly of components of the our compost toiletTo use the compost toilet, users cover their poop with a layer of carbon-rich material. In our case, this is mostly sawdust because it is a waste material that we always have on hand. Once the collection bucket in the toilet is full, we empty it into the outdoor compost pile dedicated solely to the compost toilet. The fresh layer of waste is covered with more sawdust, which immediately removes the smell and wards away flies. We then rinse the bucket, pour the rinsing water on the compost pile to help moisten the compost pile, and cover the compost pile again with fresh sawdust.

Our compost pile setup

We use our compost primarily for feces as we are an office which means the usage of this toilet for urine will be more than feces. The imbalance of the proportion of urine and feces could result in a slower composting process. A low level of urine is not an issue for the decomposition, but with our compost pile located near our living space, we want to avoid the smell that it can cause. In the active compost pile, the waste completes its conversion into humus. The temperature at the core of the active compost pile can reach upto approximately 650C. The covering material such as saw dust, hay, weeds, straw is referred as biological sponge in the figure on the right. Once the compost pile is high enough, we leave it to cure for oneyear, after which it is safe to use for gardening. The curing time for compost containing human waste is longer than most compost piles, but it ensures the extermination of pathogens present in the feces before its use.

Section through the compost pile © The Humanure Handbook: shit in a nutshell


Temperature reading from our active compost pile

Making a functional compost toilet can be challenging, so of course, we had to manage some difficulties.  First, the volume of our waste output is disproportionate to our available yard space. After just three months of using the toilet, the compost pile is half-full. Since the active compost pile still needs to be cured once it is ample, we may have to pause our use of the compost toilet at that point. If we had unlimited space in our yard, we would have had the chance to start a new compost pile. But in an urban setting like ours, that is not an option. Our second challenge is that our active compost pile is dry because we use a lot of sawdust. In order to create a hospitable environment for the suitable bacteria to break down our waste, we need to add moisture to the pile. At this point having some levels of urine present in the compost pile would help but, we use some greywater from washing dishes instead in order to avoid washing drinking water and unpleasant smell of urine. It will be also good to mention that according to “the Humanure Handbook: shit in a nutshell” by Joseph Jenkins for a household the separating urine and feces is not necessary.[9]

Rich fertile compost

Even though there are some obstacles to using a compost toilet, especially in an urban environment, the system is quite simple overall. For us, it is a way to transition from relying on a flush toilet and better our water usage while producing garden material. We will update our progress on this blog and our social media as we adapt to this new and improved option for human waste management in our headquarters.

Do’s and Don’ts © The Humanure Handbook: shit in a nutshell

 

Bibliography

[1] United Nations, “Scarcity | UN-Water,” UN-Water, 2011. https://www.unwater.org/water-facts/scarcity/.

[2] E. Saner, “The no-flush movement: the unexpected rise of the composting toilet,” The Guardian, Dec. 09, 2019.

[3] C. K. Anand and D. S. Apul, “Composting toilets as a sustainable alternative to urban sanitation – A review,” Waste Management, vol. 34, no. 2, pp. 329–343, Feb. 2014, doi: 10.1016/j.wasman.2013.10.006.

[4] “Mobile Dry Diversion Toilet FABULOUS URBAN,” Swiss-Architects. https://www.swiss-architects.com/en/fabulous-urban-zurich/project/mobile-dry-diversion-toilet?nonav=1 (accessed Oct. 06, 2021).

[5] N. Rogers, “Composting toilets could be the way of the future,” ABC News, Jun. 24, 2019.

[6] T. Avellán, “The world needs more toilets – but not ones that flush,” The Conversation, Mar. 21, 2017. https://theconversation.com/the-world-needs-more-toilets-but-not-ones-that-flush-74007 (accessed Oct. 07, 2021).

[7] “Saving water in the home,” nidirect, Oct. 20, 2015. https://www.nidirect.gov.uk/articles/saving-water-home.

[8] N. Hancock, “Safe Drinking Water Foundation,” Safe Drinking Water Foundation, Nov. 30, 2016. https://www.safewater.org/fact-sheets-1/2017/1/23/water-consumption.

[9] J. C. Jenkins, HUMANURE HANDBOOK : shit in a nutshell. S.L.: Chelsea Green, 2019.

 

The post Compost Toilet : Our response to water scarcity? appeared first on Critical Concrete.

Did you miss our previous article…
https://www.thevisualconcretegroup.com/?p=191

Cooperative housing is discussed in one module of our Sustainable-Sustainable Architecture postgraduate course; if the topics discussed in this article pique your interest, you may be a wonderful candidate. Learn more here.

Introduction

Living in a single-family unit, either in a house or apartment building has become the living standard, but it isn’t the only possibility. Many houses are equipped with appliances and rooms that are used rarely or on a weekly basis, which suggests that there may be a more functional system out there. On the other hand, many houses in urban settings are cramped and unhealthy due to the rising cost of living in cities and urban migration. This inequity is only growing with urban migration patterns and gentrification. 

The single-family housing model is not a viable paradigm for the future. Not only is it an inefficient use of space, but it is also isolating and fails to nurture community. It tends to be cramped for the poor and leaves vulnerable groups to fend for themselves. On a deeper level, these aspects are the exact opposite of what allowed early humans to create society.

Architects, theorists, and dreamers have all wondered how our dwellings can be reshaped for better quality of life and higher affordability, but to solve these issues, they don’t need to strive for the most complicated answer. Two possibilities already exist to challenge the housing paradigm. Housing cooperatives have existed for over a century and challenge the notion of housing as a commodity. Cohousing is a method of living with others to maximize space, resources, and community. These ideas have potential to not only remedy urban housing challenges, but also to home in on environmental sustainability in domestic spaces.

a basic comparison

Cooperative Housing

Housing cooperatives, or co-ops, have existed throughout history, yet in most places they are not recognized as mainstream housing possibilities. In fact, they’ve gone so far under the radar that you might be wondering what in the world a housing cooperative is. Let’s rewind.

A housing cooperative is a housing business which has shared ownership by its residents.[1] The goal of this collective ownership is affordability rather than profit.[2] Aside from collective ownership, there is one feature that is almost always present in coops: democratic processes.[3] Residents get to vote on the major decisions of the cooperative, such as who can replace a former resident, or whether solar panels should be purchased for the building. Other important elements of cooperative housing are commitment to social goals, security in community, decent housing, personal growth, and transparency in management.[4]

The modern history of housing cooperatives in Europe began in the 1800s in Berlin with Victor Aimé Huber’s cooperative dwellings.[5] The practice evolved and expanded, becoming an opportunity for decent affordable housing and as a possibility for people to have more control over their living conditions. 

Kalkbreite Cooperative in Zurich

Differences between Cooperatives

As the practice of founding co-ops spread and grew more prevalent, many differences arose. There are limited-equity coops, often for low and moderate income shareholders, market-value ownership coops, which do not require affordability; rental co-ops which have more secure tenure and have mixed-income tenants; and mutual aid co-ops which are based on solidarity and self help and are usually self-built.[6] Depending on the country and its policies, funding a new housing cooperative could rely on government, banks, or private investors. Cooperatives can be rural or urban, high rise or groups of single family housing.[7] Some co-ops began as ventures to create exclusive and wealthy multi-family housing whereas others were intended to create housing for the poor.

The most pronounced differences between cooperatives comes down to financing and legal constraints, both of which are influenced by the government where a cooperative is located. Cooperatives around the world vary subtly because of governmental constraints in their respective countries, so these are a few examples to show the possibilities.

In Austria, a country with a strong social housing sector, housing cooperatives which are below market-rate are exempt from corporation tax.[8] The government offers subsidies through public housing schemes via low-interest grants or mortgages that cover some of the construction costs.[9] In Egypt, cooperatives are exempt from many taxes, from industry profit taxes to custom taxes and importing fees, some fees including building license fees and publishing fees, and interest of deposits in banks.[10] They receive a 25% discount on state owned land which can be increased to 50%.[11] 

FCH Housing Project in Egypt

Portugal’s government reduces the VAT from 20% to 5% for cooperatives, and they also provide tax exemptions on land acquisitions and subsidize interest rates for cooperatives with low-income target groups.[12] Pakistan has a unique system for cooperative development: the state provides land to cooperatives, but cooperative shareholders are responsible for the construction of their residence on the plot they are assigned.[13] Interestingly enough, in Germany, although housing cooperatives do receive tax relief, they do not receive money from social housing funds; co-ops are not part of social housing there.[14]

The presence of housing cooperatives often hinges on politics. Since cooperatives greatly benefit from the aforementioned subsidies, tax relief, government loans, and other governmental support, proliferation of new co-ops can fluctuate with political changes. Furthermore, governments can incentivise cooperatives through policy, but they can also place limits on the founding of new cooperatives. For instance, Poland banned cooperatives in 1990, a marked difference from the years they had spent becoming mainstream during the socialist regime.[15] On the contrary, Portugal experienced an increase in co-ops after an authoritarian government which opposed the values of cooperatives was replaced.[16] In Pakistan, a corruption scandal from a cooperative paused registration of new housing cooperatives.[17]

Membership practices in cooperatives mean that even in rental cooperatives, residents are less passive inhabitants than in typical multi-family housing. Democratic foundations within cooperatives mean residents vote on management, changes, and governing structures. Each shareholder can have one vote, but in some co-ops the number of votes is equal to the number of shares. Some cooperatives require all decisions to be voted on by everyone, whereas others allow members the option of voting. Whichever way the voting system plays out, members of cooperatives have a stronger sense of ownership and participation, and can motivate one another to create a greener, healthier housing cooperative.

Student Cooperative in California via tsakett on Flickr

Cohousing

Cooperative housing shouldn’t be confused with cohousing, a modern iteration of intentional living developed in Denmark.[18] Cohousing can be implemented within cooperative housing; the two are separate systems which have potential to work together. Cohousing challenges the single family home in favor of sharing space and creating a stronger community.

Although the idea of living with others isn’t new, the term “cohousing” only arose in 1988 after two architects from the United States observed the phenomenon in Denmark, where it had gained traction.[19] Exactly twenty years prior, architect Jan Gudmand-Hoyer had spent several months discussing housing alternatives with a group of friends, developing plans for 12 houses gathered around a common space.[20] Although the project never took form, he published an influential article on the project entitled “The Missing Link between Utopia and the Dated One-Family House” which elicited responses from many families eager to live in such a situation.[21] Another article, “Children Should Have One Hundred Parents” by Bodil Graae, garnered further interest in the concept.[22] After the articles were published, families came together to purchase sites and construct two projects by 1973, which formed the blueprint for cohousing in Denmark.[23]

Rudolph Schindler House in Los Angeles via Lian Chang on Flickr

The ideas are far from new. While Gudmand-Hoyer and Graae were writing these articles, the hippie movement in the sixties was awash with communes and ideas challenging single-family living. But unlike cohousing, many hippie communes were infamous for being financially and socially unsustainable. Additionally, with roots in the early 1900’s, the intentional communities called kibbutz are well known examples shared living from Israel. In California, the Austrian architect Rudolph Schindler built one of the first ever modernist houses, designed for two families to live cooperatively and share one common kitchen.[24] All this is to say that cohousing is not a particularly unique idea, although its less radical stance is possibly what makes it such a viable housing option.

However, what differentiates cohousing from similar ideas like kibbutzim or ecovillages is that cohousing is primarily an architectural design which fosters community alongside a social agreement to live cooperatively. It does not have ideological connotations and can manifest in various ways. Cohousing can be rural or urban, meaning unlike other kinds of intentional communities, it can respond to the global urban influx. Additionally, cohousing may be equipped to handle the challenges of  urban living, such as elder- and childcare along with social isolation. Some cohousing situations share chores in common spaces such as cooking, which tends to free up time for those with busy schedules. 

Spreefeld Berlin Via MitOst on Flickr

Sustainability in Cohousing

Cohousing has some inherent advantages for sustainability. First, dense dwellings groups are more efficient to heat or cool. If the kitchen and living areas are shared, less furniture is needed and kitchen appliances only need to be purchased once for multiple families. By living in close proximity, people can share their skills, which means residents can help each other with tasks like repairing broken items instead of wasting them and buying new things. Additional benefits include purchasing food in bulk, which is better for transportation and uses less packaging. Shared garden spaces mean some food can also be cultivated in a community garden. Having a garden also provides a space to incorporate a compost bin, a challenging feature for typical urban housing.

Cohousing also has the benefit of community learning and social practices, which helps propagate care for the environment and ecological values.[25] By living with many people, there can be less car dependence. Tasks like grocery shopping can be divided and commuting to work can be done with fewer cars.[26] Finally, shared meals can result in lower food waste.[27]

Vauban Cohousing in Freiburg

Housing More Sustainably

There is potential for even more sustainability in cohousing projects. The fact that many cohousing projects are cooperatively owned, purchased before construction is complete, or even designed with input from the future residents is something that allows for even more ecological interventions. If cohousing projects are designed with sustainability in mind, they can be more energy efficient and prioritize passive sustainable strategies. For instance, common areas can incorporate daylighting and efficient ventilation. The design can include a root cellar to store vegetables for long periods in winter without the use of a fridge. Natural materials such as hempcrete, mycelium, cork, rammed earth and many more could all be used as building materials. Since some cohousing projects include aspects of self-building or auto-construction, materials and techniques are employed with easy repairability and designs that factor in longevity. Some features of sustainable design, like solar panels, come at a premium, but if a project is cooperatively owned, these additional costs are spread out among all the owners.

Occupant ownership via the housing cooperative model also means that there can be experimental sustainable practices that wouldn’t usually be possible in conventional multi-family housing. A garden could be designed to have a phytodepuration wastewater treatment system, which would simultaneously provide a beautiful marsh landscape in the common area. There could be compost toilets, green roofs, or food forests, too. With an ecological group of residents, there is also potential for the use and maintenance of a biodigester to produce biogas for cooking. The possibilities are endless, especially with lots of community minded people with various skills willing to contribute to communal projects.

Conclusion

Cohousing and cooperatives are two approaches to financial and ecological housing issues. They provide a peek into what housing would look like if we didn’t approach it from a single-family perspective. When the concepts are combined, they create feasible models for better living conditions, affordable housing, and stronger communities. Moving away from profit and towards collective action gives an added opportunity for a more ecological way of living. Existing cohousing cooperatives are great launch pads for pushing the possibilities of environmentally sustainable multi-family housing, while budding cohousing cooperatives have the opportunity to design healthy living spaces for both people and the planet. 

[1] https://4bfebv17goxj464grl4a02gz-wpengine.netdna-ssl.com/wp-content/uploads/drupal/Profiles%20of%20a%20movement%20final%20web%20ISBN.pdf

[2] Note: There are some cooperatives which are not intended to be affordable housing, but the collective ownership does improve the affordability, even in those cases.

[3] https://www.ica.coop/en/events/cooperative-housing-key-model-sustainable-housing-europe

[4]https://4bfebv17goxj464grl4a02gz-wpengine.netdna-ssl.com/wp-content/uploads/drupal/Profiles%20of%20a%20movement%20final%20web%20ISBN.pdf

[5] https://www.housingeurope.eu/event-183/cooperative-housing

[6] https://www.housinginternational.coop/sdgs-2/cooperative-housing-models/

[7] https://4bfebv17goxj464grl4a02gz-wpengine.netdna-ssl.com/wp-content/uploads/drupal/Profiles%20of%20a%20movement%20final%20web%20ISBN.pdf

[8] https://4bfebv17goxj464grl4a02gz-wpengine.netdna-ssl.com/wp-content/uploads/drupal/Profiles%20of%20a%20movement%20final%20web%20ISBN.pdf

[9] Ibid.

[10] Ibid.

[11] Ibid.

[12] Ibid.

[13] Ibid.

[14] Ibid.

[15] Ibid.

[16] Ibid.

[17] Ibid.

[18]  https://www.cohousing.ca/about-cohousing/history-of-cohousing/

[19] http://www.cohousingco.com/cohousing

[20] https://www.cohousing.ca/about-cohousing/history-of-cohousing/

[21] Ibid.

[22] Ibid.

[23] Ibid.

[24] https://www.archdaily.com/783384/ad-classics-kings-road-house-rudolf-schindler

[25] https://www.iberdrola.com/social-commitment/cohousing

[26]  https://www.moneycrashers.com/communal-living-cohousing-types-benefits-intentional-communities/

[27]  https://www.moneycrashers.com/communal-living-cohousing-types-benefits-intentional-communities/

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