Primitive Technology: Geopolymer Cement (Ash and Clay)

Primitive Technology

2 May 202411:59

Summary

TLDRThis video script details a unique and traditional process of creating cement using wood ash. It begins with making fire by friction at a brick hut, where wood is burned for ash, which also aids in drying bricks. The wood ash is then sifted to remove charcoal, mixed with water to form a paste, and shaped into pellets or clinkers. A single pellet is set aside to air dry, while the rest are calcined in a forge until they glow red hot. The calcined ash is then mixed with water and shaped into a cube without any aggregate. Subsequently, aggregate is created from crushed old bricks or pottery, and various ratios of ash to fired clay are tested to determine the optimal mixture for strength and cohesion. The video also explores the use of uncalcined and calcined ash, demonstrating that only ash subjected to high heat is suitable for cement. Experiments with different materials, such as sand, are conducted, and the process is refined to produce a fast-setting geopolymer cement using the leftover ash from previous firings. The video concludes with the successful water resistance test of the samples, showcasing the potential of this method for creating sustainable and efficient building materials.

Takeaways

🔥 The process begins with making fire by friction, which is used to burn wood for ash, also serving the dual purpose of drying bricks.
🏚 The wood ash is collected and sifted to remove charcoal, then mixed with water to form a paste, which is later formed into pellets or clinkers for firing.
⚗️ An uncalcined pellet is set aside to air dry, while the rest are calcined in a forge, requiring the pellets to glow red hot for proper calcination.
🧱 To create cement, the calcined pellets are mixed with water again and molded into shape, specifically a cube of calcined ash without aggregate.
👷‍♂️ Aggregate is made from crushed old bricks or pottery, with varying ratios of ash to fired clay tested for structural integrity.
🌟 A key observation is that only ash that has been very hot (calcined) is suitable for making cement, as demonstrated by a dissolving resistance test.
🔨 An experiment with a grate for a furnace is described, where the ash is used to make a cylindrical clinker, which is then fired using natural draft for efficiency.
📈 The experiment shows that using sand instead of fired clay in a 1:3 ratio with ash produces a slightly weaker but still viable cement.
⏱️ A fast-setting geopolymer cement is developed, with a sample surviving a 24-hour water test after only 6 hours of setting.
🔄 The potential for using the leftover ash from previous firings without further calcination is explored, suggesting a sustainable and efficient method.
🏗️ The script concludes by emphasizing the need for more experiments to scale up the process and determine the types of structures that can be created with this method.

Q & A

What is the primary purpose of burning wood in the brick making hut?
-The primary purpose of burning wood in the brick making hut is to create ash, which is used to make cement, and also to dry the bricks.
How is the wood ash processed before it can be used for making cement?
-The wood ash is sifted to remove most of the charcoal, then mixed with water to form a paste, which is subsequently formed into pellets or clinkers to be fired.
What is the significance of calcining the ash pellets in the forge?
-Calcining the ash pellets is crucial as it heats them to a high temperature, which is necessary for the ash to be suitable for making cement. Only ash that gets very hot is considered suitable.
How does the uncalcined pellet differ from the calcined block in terms of appearance?
-The uncalcined pellet has a dull surface, while the calcined block has a glossy surface, indicating the transformation that occurs during the calcination process.
What is the role of aggregate in the cement mixture?
-Aggregate, such as crushed old bricks or pottery, is mixed with the ash to improve the structural integrity of the cement. Different ratios of ash to fired clay are experimented with to find the optimal balance.
Why is the uncalcined ash pellet less suitable for cement compared to the calcined ash?
-The uncalcined ash pellet dissolves when put in water for a dissolving resistance test, indicating it is not suitable for cement. In contrast, all samples that used calcined ash survived the test, showing their suitability.
How does the process of making a grate for a furnace contribute to the efficiency of the firing process?
-The grate allows for better airflow and a more efficient, hotter burn compared to a fire on the ground. It also simplifies the process by using natural draft without the need for a blower.
What is the significance of the 1:3 ratio of ash to sand or fired clay in the cement mixture?
-The 1:3 ratio is found to be effective in creating a cement mixture that can survive a water test after 24 hours. It represents a balance between the binding properties of the ash and the structural integrity provided by the sand or fired clay.
What is the advantage of using ash left over from the previous firing in the next batch?
-The leftover ash is assumed to have been sufficiently heated during the previous firing, eliminating the need for further calcination. This could simplify the process and save time and energy.
How does the experiment with different shapes of the same material affect the outcome?
-Different shapes of the same material (ash and fired clay mixture) are tested to see if the shape has any impact on the performance of the cement. The results indicate that the material composition is more critical than the shape for the cement's effectiveness.
What is the key takeaway from the experiment with the fast-setting geopolymer cement?
-The key takeaway is the discovery of a simple method for producing a fast-setting geopolymer cement using a 1:1 ratio of ash to fired clay, which can survive in water after only 6 hours of setting, suggesting potential for rapid construction applications.
What is the next step proposed after these experiments?
-The next step proposed is to conduct more experiments to scale up the process and explore what structures can be made using this method of producing cement.

Outlines

00:00

🔥 Brick Making and Ash Processing

The video begins with the process of making bricks, starting with creating fire by friction at the brick making hut. Wood is burned to produce ash, which is then used for both drying bricks and as a primary material. The ash is sifted to remove charcoal, mixed with water to form a paste, and then shaped into pellets or clinkers for firing. One pellet is set aside to air dry, while the rest are calcined in a forge. The calcination process requires the pellets to glow red hot. Subsequently, the calcined pellets are mixed with water and shaped into a cube without aggregate. Old bricks or pottery are crushed to create an aggregate, mixed with ash in various ratios (1:1, 1:2, 1:3), with a 1:4 ratio proving insufficient for cohesion. The difference in surface texture between uncalcined and calcined pellets is highlighted, with the uncalcined pellet having a dull surface.

05:03

🧪 Cement Testing and Furnace Construction

The video continues with a series of tests to determine the dissolving resistance of the ash-based cement. A week of curing is followed by a water test, where it's observed that only the calcined ash samples survive, indicating that high heat is necessary for a suitable cement. The presenter then proceeds to make a grate for a furnace, which is used to sift ash of charcoal and form a cylindrical clinker. The clinker is placed on the grate within the furnace, which is then stacked with wood and lit from the top for a more efficient burn. The process is designed to use natural draft rather than a blower, to simplify and reduce labor. The furnace is sealed with mud, and the clinker is calcined. After calcination, the clinker is crushed and mixed with sand and fired clay in a 1:3 ratio, and the different samples are tested for water resistance after 2 days.

10:06

🏗️ Fast Setting Geopolymer Cement Experiment

The final part of the video focuses on further experimentation with the geopolymer cement. Using the ash leftover from the previous firing without additional calcination, a 1:3 ratio of ash to fired clay is tested. When it doesn't stick well, more ash is added to reach a 1:1 ratio. This new mixture is subjected to a water test after only 6 hours and surprisingly survives for 24 hours. This discovery leads to the conclusion of a simple method for producing a fast-setting geopolymer cement. The video ends with a note on the need for more experiments to scale up the process and explore the potential for constructing various structures with this innovative material.

Mindmap

Keywords

💡Friction

Friction is the resistance that one surface or object encounters when moving over another. In the context of the video, it is used to describe the process of making fire, which is essential for burning wood and initiating the brick-making process. The script mentions 'Making fire by friction' as the first step, highlighting its fundamental role in the procedure.

💡Wood Ash

Wood ash is the residue left after the combustion of wood. It contains various compounds, including salts of potassium, calcium, and magnesium, which can be used in different applications such as agriculture and construction. In the video, wood ash is crucial for creating a paste and forming the base for the cement. The script describes how the ash is sifted, mixed with water, and used in different ratios with fired clay to produce the cement.

💡Calcination

Calcination is a thermal process in which a substance is heated to high temperatures in the presence of air, causing it to undergo a thermal decomposition. In the video, calcination is a key step in the production of cement, as it involves heating the ash pellets in a forge until they glow red hot. This process transforms the ash into a form suitable for making cement, as illustrated by the script when it states, 'The pellets must glow red hot for them to be properly calcined.'

💡Aggregate

An aggregate is a material that has been破碎 (crushed) and used to blend with a binder to create a composite material. In the context of the video, aggregate refers to the crushed old bricks or pottery that is mixed with the ash to create a stronger cement mixture. The script discusses various ratios of ash to fired clay and ash to sand, indicating the importance of aggregate in determining the strength and properties of the final product.

💡Curing

Curing is the process of allowing a material to harden or set by applying specific conditions, such as time, temperature, or moisture. In the video, curing is mentioned as a week-long process for the cement samples to gain strength before undergoing a dissolving resistance test. The script notes, 'A week of curing, the samples are put in water for a dissolving resistance test,' emphasizing the importance of curing in the cement's development.

💡Dissolution Resistance

Dissolution resistance refers to the ability of a material to withstand the process of dissolving when in contact with a solvent, such as water. In the video, this property is tested to evaluate the quality of the cement. The script describes a test where samples are submerged in water, and it is observed that 'All samples that used calcined ash survived,' indicating that the calcined ash contributes to the dissolution resistance of the cement.

💡Geopolymer Cement

Geopolymer cement is a type of binder that is made from natural or industrial mineral sources and has properties similar to those of Portland cement. The video describes an experiment with a geopolymer cement made from wood ash and fired clay. The script mentions, 'We now have a simple method for producing a fast-setting geopolymer cement,' which suggests that the process outlined in the video can be used to create a sustainable and efficient alternative to traditional cements.

💡Natural Draft

Natural draft refers to the flow of air through a system due to differences in air density, typically caused by temperature differences, without the use of mechanical devices like blowers. In the video, natural draft is utilized in the furnace to save labor and simplify the process of calcining the ash. The script states, 'This time the firing will work by natural draft (no blower),' highlighting an efficient and low-tech approach to the process.

💡Furnace

A furnace is a type of equipment used for heating, melting, or chemically treating materials, typically by burning fuel. In the video, a furnace is used to calcine the ash clinker and is described as being set up with a grate and clay to hold it in place. The script details the process of placing the clinker in the furnace and lighting the fire, demonstrating the furnace's role in the production of the cement.

💡Sintering

Sintering is a process used to agglomerate powders into a solid mass, typically by heating without reaching the melting point. In the context of the video, sintering is implied during the calcination of the ash pellets in the forge, where they are heated until they glow red hot. The script does not explicitly mention sintering, but it is a process that would occur when pellets are 'burnt with wood in the forge' and 'glow red hot,' contributing to the formation of the cement.

💡Ratio

A ratio is a mathematical expression that compares two or more quantities. In the video, different ratios of ash to fired clay or ash to sand are experimented with to determine the optimal composition for the cement. The script provides various examples, such as '1:1 ash to fired clay' and '1:3 ash to sand,' to illustrate how varying the ratio affects the cement's properties and performance.

Highlights

Making fire by friction at the brick making hut is the initial step in the process.

Wood is burned for ash, which serves a dual purpose of drying bricks and providing ash for cement.

Wood ash is sifted to remove most of the charcoal before use.

Ash is mixed with water to form a paste, which is then shaped into pellets or clinkers for firing.

One ash pellet is set aside to air dry, while the rest are calcined in a forge.

Calcination of pellets requires them to glow red hot for proper processing.

Cement is formed by mixing calcined pellets with water and shaping them into cubes without aggregate.

Aggregate for cement is made from crushed old, broken bricks or pottery.

Different ratios of ash to fired clay are experimented with, from 1:1 to 1:4.

Uncalcined pellets have a dull surface, while calcined blocks have a glossy surface.

A week-long curing process is implemented before a dissolving resistance test in water.

Only calcined ash that gets very hot is suitable for making cement.

A grate is made for the furnace to simplify the process and save labor.

Firing the clinker in the furnace uses natural draft, eliminating the need for a blower.

The furnace is modified for better natural draft by raising its height and sealing joints with mud.

Burning wood on a grate is more efficient and reaches higher temperatures than a ground fire.

Experiments with different materials show that a 1:3 ratio of ash to sand or fired clay works well.

A sand sample is slightly weaker and more easily scratched compared to others.

Using ash from the previous firing, which requires no further heat treatment, results in a fast-setting geopolymer cement.

A simple method for producing a fast-setting geopolymer cement with a 1:1 ratio of ash to fired clay is discovered.

Further experiments are needed to scale up the process and determine what structures can be created.