Literature Review
Cement Powder Compared to Refined Sand
ABSTRACT :
Advancements in technology are constantly changing and pushing the limits of conventional working practices.These constant changes have led to the development of new materials and construction practices that expedite the construction process. Building upon existing research, this project seeks to develop a viable solution that would replace gravel with engineered plastics. We will begin our research by examining existing electron microscope images of concrete, minerals, and crystals to further study their geometric properties. Additionally, we will use 3d software to visualize and replicate possible engineered geometries. Using 3D printers we will develop a series of prototype aggregates that would be added to a concrete mix to be tested. Such prototypes will be used to measure the changes in the tensile and compressive properties of concrete. If successful, our engineered geometries would be able to provide viable solutions for one-time plastic waste, gravel mining, as well as a possible means to extend concrete life by reducing the amount of steel used in rebar applications.
PREMISE :
In our society concrete has become a crucial part of our everyday life. Its structural qualities and aesthetics have turned it into a commodity. This is due mainly to two factors. The first being the ease of access to which we approach the material. Our uses can range from a small 80 lb bag of concrete mix to a truck load equivalent to a total of 15 cubic yards. Having access to large quantities of concrete mix, all at once, is a commodity. Yet the second factor that we seem to ignore is the actual delivery of the material. Ready mixed concrete is more often than not, ready to pour as soon as the truck starts to move it. However, while concrete has become a commodity, its manufacturing process has created a large carbon footprint. Additionally, just as concrete has become a primordial material in any urban context, plastic pollution has also come a part of our everyday life. Plastics, being the commodity that they are, don't contribute to anything to society other than their once time use.
While it may seem like the solution to plastic pollution is to stuff plastic into concrete since its one of the most abundant structural systems; adding plastic to concrete is not so simple. Learning more about the material similarities and differences between concrete and plastic may inform a more objective synthetization of the two materials. For example, by studying technologies that are exclusively used in concrete applications we may find a scenario in which plastic may be functional. Additionally, we may find a scenario in which the concrete may expand or build upon existing practical plastic applications. This can serve as a platform to objectify the research and derive the project from a specific need within the construction industry.
THE BREAKDOWN :
While the intent is to use re-purposed plastics as solid aggregates in concrete mixtures, there is an understanding that not all plastics will be viable for this application. Due to different chemical bonds and decay processes, using plastics becomes a matter or researching and perhaps testing their molecular arrangement. Having that said, plastic may not be the solution to all concrete aggregate applications. Currently there are some applications in which concrete waste is being re-purposed to replace a large portion of Portland cement, thereby yielding a stronger concrete mixture. (-----,-----) Additionally, finer aggregates are also composed of re-purposed concrete. So the notion of re-purposing the waste of a product and applying it to the same production process is not new.
In addition to that, there is precedence for the re-purposing of plastics as well. There are companies that specialize in the production of 3D printed filament that is made from recycled plastics and there are others who specialize in the manufacturing of devices that can convert plastic into filament, making the recycling process more accessible and affordable.(-----,-----) With this in mind it's possible to rethink the way in which plastic can be synthesized with concrete. It would no longer be a matter of shredding plastic and dumping it into concrete, per say. The solution could be an engineered additive that mimics the properties of gravel.
Concrete Technologies
Even though concrete has been used in construction processes for centuries, scientists and engineers alike, are continuously testing potential solutions to production time, waste add-mixtures, structural improvements, as well as effective recycling solutions including chemical and mineral compositions. .
We can take advantage of the irregularities that concrete and plastic have in order to create somewhat accurate results. the amalgamation of the two materials may be able to inform more about the current thinking process that combines the two; in order to think of new ways of adapting materials to the conditions of one another.
Plastic Technologies :
The plastic technologies that we have found to be more adaptable to our research are those involving the use of Polyethylene-terephthalate. This type of plastic “is a general-purpose thermoplastic polymer which belongs to the polyester family of polymers. Polyester resins are known for their excellent combination of properties such as mechanical, thermal, chemical resistance as well as dimensional stability.” (-----,----) This type of plastic is “strong, and lightweight, widely used for packaging foods and beverages, especially convenience-sized soft drinks, juices and water.” (----,----). Its feasible accessibility and high consumption rate make it one of the most widely used pollutants being made. Additionally, we will focus our research on the properties of new technologies that are both feasible to use at a moderate production scale and are safe for the environment. Those being 3d printing, the recycling of waste plastic and converting it into 3D printable filament, and the insertion of biodegradable materials into the 3d printing process including possibilities and limitations.
Existing Hybridization of Plastic and Concrete :
Current research that seeks to use plastic as an aggregate in concrete mixtures is very broad in terms of context and application, but it is also very narrow in specific fields. The works we have found and selected cover major areas of research; those being, compression strength, tensile strength, curation, insulation, as well as applications, and specific mixture replacements. For the most part, all of the research aims at light weight concrete mixtures. The use of plastic does not yield the same results as gravel would for compression tests, making the use of plastic aggregates limiting in structures above 3 stories high. Additionally, most tests that involve concrete seem to follow a standard testing procedure that tests for more that one variable. For example, some tests proved no structural performance gains in compression or tensile strength but they did show some improvement in insulating capacities. The range of tests, again, includes compression strength, tensile strength, curation, insulation, weight, density, water absorption, porosity, and water pressure.
The list of projects covered will range from plastic type to possible applications.
So far we have only found two projects that have considered the geometric form of the plastic. The first is the beads project and a separate study that test for compressive efficiency. The shape of those pieces was pellet shaped (cylindrical), and roughly about the size of a 1 cent coin.
On the other hand, we have found multiple examples of the possible geometries that can be crafted using a 3D printer. The best example was the gyroid developed by an MIT student. The engineering of the gyroid object may prove to be a reinforcing structure, similar to rebar. The only issue would be the chemical reaction between cement and PLA once it is allowed to cure. The decay of 3D printed objects may be accelerated or it very could be fossilized within the concrete.
How do we move forward after the initial amount of research that we have gathered ?
Imagine this:
Crystalline structures: Current research shows interest in the possibility of enhancing concrete in a microscopic scale.
What if we were able to replicate such crystalline structures and scaled them to the size of gravel ? As architects we are trained in creating metaphors that are able to transcend various types of scales and proportions. Could this be a design challenge in the sense that the we are "geo-mimicking" speculative forms interpreted from electron scans ? The exercise of extracting the geometry from an image wouldn't be so much different than sketching. The only difference is that it would be a 3D sketch of a crystalline structure.
3D Printing using B-Pet : We know that PolyEthylene Terephthalate is one of the most common used plastics therefore being one of the largest polluters. It could become the single largest source for creating recycled B-Pet filament. The sketched crystalline geometries could be 3d printed with this material, creating a net zero waste scenario in which emissions aren't drastically used and plastic is being removed from the environment.
Testing : Current research has focused on using shredded plastic with a minimum number of examples focusing on the geometric properties that could help concrete bind better; similar to how gravel would help concrete bind. Also, thinking of the thermal properties of plastic, it is also possible to test if any 3d printed volume, embedded within concrete would be able to provide any enhancement to insulating properties.
Concrete Application: Not looking far, the scope of the project could simply stay focused on the minimal applications that current plastic-concrete applications have; that being light weight concrete. The research would focus on creating a series of scenarios in which several geometries are developed in order to be embedded as a whole or in small segments to mimic gravel. The test would be composed of a compression test to visualize how concrete deforms, and if the geometry embedded provides any actual support. Prior to that, samples would be tested for insulating properties, and curation times and fabrication times for processing.
Advancements in technology are constantly changing and pushing the limits of conventional working practices.These constant changes have led to the development of new materials and construction practices that expedite the construction process. Building upon existing research, this project seeks to develop a viable solution that would replace gravel with engineered plastics. We will begin our research by examining existing electron microscope images of concrete, minerals, and crystals to further study their geometric properties. Additionally, we will use 3d software to visualize and replicate possible engineered geometries. Using 3D printers we will develop a series of prototype aggregates that would be added to a concrete mix to be tested. Such prototypes will be used to measure the changes in the tensile and compressive properties of concrete. If successful, our engineered geometries would be able to provide viable solutions for one-time plastic waste, gravel mining, as well as a possible means to extend concrete life by reducing the amount of steel used in rebar applications.
PREMISE :
In our society concrete has become a crucial part of our everyday life. Its structural qualities and aesthetics have turned it into a commodity. This is due mainly to two factors. The first being the ease of access to which we approach the material. Our uses can range from a small 80 lb bag of concrete mix to a truck load equivalent to a total of 15 cubic yards. Having access to large quantities of concrete mix, all at once, is a commodity. Yet the second factor that we seem to ignore is the actual delivery of the material. Ready mixed concrete is more often than not, ready to pour as soon as the truck starts to move it. However, while concrete has become a commodity, its manufacturing process has created a large carbon footprint. Additionally, just as concrete has become a primordial material in any urban context, plastic pollution has also come a part of our everyday life. Plastics, being the commodity that they are, don't contribute to anything to society other than their once time use.
While it may seem like the solution to plastic pollution is to stuff plastic into concrete since its one of the most abundant structural systems; adding plastic to concrete is not so simple. Learning more about the material similarities and differences between concrete and plastic may inform a more objective synthetization of the two materials. For example, by studying technologies that are exclusively used in concrete applications we may find a scenario in which plastic may be functional. Additionally, we may find a scenario in which the concrete may expand or build upon existing practical plastic applications. This can serve as a platform to objectify the research and derive the project from a specific need within the construction industry.
THE BREAKDOWN :
While the intent is to use re-purposed plastics as solid aggregates in concrete mixtures, there is an understanding that not all plastics will be viable for this application. Due to different chemical bonds and decay processes, using plastics becomes a matter or researching and perhaps testing their molecular arrangement. Having that said, plastic may not be the solution to all concrete aggregate applications. Currently there are some applications in which concrete waste is being re-purposed to replace a large portion of Portland cement, thereby yielding a stronger concrete mixture. (-----,-----) Additionally, finer aggregates are also composed of re-purposed concrete. So the notion of re-purposing the waste of a product and applying it to the same production process is not new.
In addition to that, there is precedence for the re-purposing of plastics as well. There are companies that specialize in the production of 3D printed filament that is made from recycled plastics and there are others who specialize in the manufacturing of devices that can convert plastic into filament, making the recycling process more accessible and affordable.(-----,-----) With this in mind it's possible to rethink the way in which plastic can be synthesized with concrete. It would no longer be a matter of shredding plastic and dumping it into concrete, per say. The solution could be an engineered additive that mimics the properties of gravel.
Concrete Technologies
Even though concrete has been used in construction processes for centuries, scientists and engineers alike, are continuously testing potential solutions to production time, waste add-mixtures, structural improvements, as well as effective recycling solutions including chemical and mineral compositions. .
- Concrete construction : Current technologies such as 3d printing have allowed us to minimize labor costs as well as concrete waste. We can refer to these as “additive manufacturing technologies.” Additionally, there are chemical and material additives that have been engineered to fasten or slow down the curating process in order to increase the strength of concrete. (-----,---)Another example of this is the introduction of light weight concrete. Lightweight concrete uses special chemical reactions that expand and create gases. Such gases then make bubbles that retain their shape until concrete is cured. This chemical approach to concrete manufacturing has also proven to reduce time and waste material, while improving compressive strength. (-----,----)
- Concrete Waste Add-Mixtures: In addition to the manufacturing technologies, there is research being conducted on “new treatment technologies.” This research consists of using “slurry” waste, (a by-product of industrial, refining or wastewater treatment processes.) (-------,--------) This research aims at creating an aggregate that would minimize the cost of extracting new materials and processing them in order to be mixed with concrete. The watery and grainy mixture of slurry aggregates proves to be advantageous in small scale applications. The issues lie with the concentration of chemicals combined between the production of Portland cement and the wide ranges of chemicals that would be embedded within slurry waste. (----,----)
- Recycling Solutions : Within the discourse of concrete production and post decomposition, there is some research that aims at re-purposing aged or demolished concrete waste. Some of the re-purposing consists of using the waste of concrete as part of a new concrete mixture as a solid aggregate or as a replacement to sand. (----,----) The aim of this research is to reach a “waste-free” system that can take full advantage of concrete as it breaks down without the chemical by-products being released into the biosphere.
- Crystalline Technology: Research has been furthered by the study of the walls surrounding the city of Rome. Compared to standard concrete utilization today, Roman concrete has proven to resist the weathering of time. The research on the chemical properties of the Roman walls proves that the secret to the strength to Roman concrete is “seawater.” According to the research, the chemical reaction created through the combination of volcanic ash and seawater allowed crystals to grow within concrete over a longer curation time. Contradicting to current concrete applications, salt water would be detrimental to existing chemical add-mixtures. (----,----)Additionally, research conducted by UC Berkeley, amongst others, seeks to improve today’s concrete by following the steps of the Romans and developing a different crystallization technique. This use of micro-structural properties is being coined as “Crystalline Technology.” (-----,-----)
We can take advantage of the irregularities that concrete and plastic have in order to create somewhat accurate results. the amalgamation of the two materials may be able to inform more about the current thinking process that combines the two; in order to think of new ways of adapting materials to the conditions of one another.
Plastic Technologies :
The plastic technologies that we have found to be more adaptable to our research are those involving the use of Polyethylene-terephthalate. This type of plastic “is a general-purpose thermoplastic polymer which belongs to the polyester family of polymers. Polyester resins are known for their excellent combination of properties such as mechanical, thermal, chemical resistance as well as dimensional stability.” (-----,----) This type of plastic is “strong, and lightweight, widely used for packaging foods and beverages, especially convenience-sized soft drinks, juices and water.” (----,----). Its feasible accessibility and high consumption rate make it one of the most widely used pollutants being made. Additionally, we will focus our research on the properties of new technologies that are both feasible to use at a moderate production scale and are safe for the environment. Those being 3d printing, the recycling of waste plastic and converting it into 3D printable filament, and the insertion of biodegradable materials into the 3d printing process including possibilities and limitations.
- 3D Printing : Although 3D printing has been around since the 80’s, it has recently attracted a wide range of fabricators and engineers. The use of 3D printing has completely revolutionized the way we make objects. The application of 3d printed technology doesn't only apply to plastics. Some printers have the capability to print metal objects. Furthering the range of possibilities.(----,-----)Even though it takes a while for the construction industry to fully accept new methods of construction, the application of 3D technology is already being tested by using concrete as a material that can be layered and extruded continuously while retaining its shape during curation. (------,------)
- Recycled Filament : B-Pet effectively recycles Pet waste into fully functional 3D printing materials. (----,----) B-PET is composed of PolyEthylene Terephthalate. This is the same material that plastic bottles as well as shampoo, and laundry detergent bottles are made of. The material itself is structurally stable and harmless.In its original state, the plastic is colorless and crystal clear. Additionally, it’s vapour barrier and strength properties makes it the ideal candidate as aggregate for concrete.. In its original state, it’s a colorless and crystal clear material.(-----,-----)
- Polylactic Acid, also known as PLA or polyactide “is obtained from renewable and natural raw materials such as corn. The starch (glucose) is extracted from the plants and converted into dextrose by the addition of enzymes. With this in mind, we must note that there is a difference between “biodegradable and compostable.” In terms of 3D printing there is a difference between how filament can degrade through biological processes, and how a material is compostable. (----,----) just because the material can biodegrade naturally doesn't mean that it can be used quickly as compost and help with the agricultural process. While PLA is extremely resilient in its applications it is very limiting in the re-purposing of its by-product. Similar to concrete, its remnants can be reused in the making of new filament, but this can also be done for a limited number of times before the material itself can no longer be used. Additionally, since the material is made from corn, there is wide debate concerning the full scope of PLA applications. The worst case scenario would be competing with food farms so that food production and biodegradable production are equally in balance.
- Gyroid Geometry :
Existing Hybridization of Plastic and Concrete :
Current research that seeks to use plastic as an aggregate in concrete mixtures is very broad in terms of context and application, but it is also very narrow in specific fields. The works we have found and selected cover major areas of research; those being, compression strength, tensile strength, curation, insulation, as well as applications, and specific mixture replacements. For the most part, all of the research aims at light weight concrete mixtures. The use of plastic does not yield the same results as gravel would for compression tests, making the use of plastic aggregates limiting in structures above 3 stories high. Additionally, most tests that involve concrete seem to follow a standard testing procedure that tests for more that one variable. For example, some tests proved no structural performance gains in compression or tensile strength but they did show some improvement in insulating capacities. The range of tests, again, includes compression strength, tensile strength, curation, insulation, weight, density, water absorption, porosity, and water pressure.
The list of projects covered will range from plastic type to possible applications.
- Plastic Bags : The research involving the use of plastic bags to tests for micro-structural strength and durability of shredded plastic. The percentage of shredded plastic of any mixture were 0%, 0.5%, 1.2%, 3%, and 5%. At those percentages, shredded plastic did not provide any added structural strength, and it was deemed to be applicable for not structural or load bearing concrete work. (---,-----)
- Recycled Composite / Plastic aggregates: The specific goal of this experiment was to test the mechanical properties of plastic aggregates in concrete, rather than the structural properties. Some of the results yielded showed extended durability in terms of water permeability. Additionally there was improved electrical resistance, as well as vibration absorption. The data showed that this specific mixture would work for railway track applications. (----,-----)
- RPA (Recycled Plastic Aggregates) : This project was shaped into a series of tests that specifically proposed the use of RPA’s as part of lightweight concrete applications. The concrete samples were tested for compression, flexural stability, as well as tensile strengths.(----,----)
- Glass + Plastic: In addition to plastic being used as the replacement for one aggregate, some researches opted to use multiple aggregate replacements. This tests specifically tested glass and plastic add-mixtures as part of the replacements. The tests were based off of a 0%, 10%, 20%, 30%, 40%, and 50%, replacement of some aggregate. The resulting samples were tested for uniaxial strength, tensile strength, as well as capillary water uptake. Even though the mixtures were deemed safe for footpath construction, some of the tests also resulted in low adhesion. (----,-----)
- Cork and Plastic : The research behind this test was also looking for a solution to light weight concrete mixtures and applications. The plastic tested was “polypropylene, also known as polypropene, is a thermoplastic polymer used in a wide variety of applications and is partially crystalline and non-polar” (----,---) The concrete samples were tested for compression, elasticity modulus, mercury intrusion, carbonation, and penetration under water pressure. The results registered low porosity as well as a high resistance to chemical attacks and high durability for chemical attacks. (----,---)
- Plastic Beads : Compared to other plastic applications, this project actually introduced recycled plastic as a geometry rather than just shredded or grinded down to a pulp. These RPBs (recycled plastic beads) were used to replace river sand in the mixture. The tests mainly covered the weight of the sample, its density, as well as the water absorption, and its thermal insulating properties. Those of which proved to be somewhat successful since the beads worked similar to a desiccant. The results, again, deemed the concrete to be strong enough for lightweight applications. (----,----)
- Temperature and cyclic loading : The research on temperature and cycling loading really narrowed down the methodology for how to test the thermal capacities of “plastic concrete.” Additionally, testing for cyclic loading appeared to reveal more results than a normal compression test. Overall the research proved that plastic configurations used provided no enhancement to tensile properties, which allowed the concrete to crack under constant stress or constant heat temperature changes. (-----,-----)
- E-Waste : Some of the research done up to date also looks into aggregates that could eventually replace sand in concrete mixtures. E-waste is basically any type of plastic used in electronic packaging (polystyrene) that is no longer usable. The material can be grinded down to grain like mixture and added to concrete as a partial replacement to sand. The application yielded positive results a partial replacement. It was reiterated that the use of this material highly compensated for the disposal problem, additionally, the use of this material at a large scale would provide enough energy and emissions reduction, which would eventually offset the total cost of concrete production. (----,----)
- Crystalline structure change : Current research being done by MIT consists of exposing plastic flakes to gamma radiation in order to change their crystalline structure. Similar to the approach of crystallization in concrete, this research aims at creating an aggregate that could replace sand entirely. The mixture they created consisted of plastic powder, cement paste, as well as fly-ash. The result yielded was 15% stronger than average concrete. The research deepened by explaining that “concrete produces about 4.5% of the world's carbon monoxide. Replacing sand alone would cut about 1.5%, which totals about 0.675% of world emissions.” (---,---)
So far we have only found two projects that have considered the geometric form of the plastic. The first is the beads project and a separate study that test for compressive efficiency. The shape of those pieces was pellet shaped (cylindrical), and roughly about the size of a 1 cent coin.
On the other hand, we have found multiple examples of the possible geometries that can be crafted using a 3D printer. The best example was the gyroid developed by an MIT student. The engineering of the gyroid object may prove to be a reinforcing structure, similar to rebar. The only issue would be the chemical reaction between cement and PLA once it is allowed to cure. The decay of 3D printed objects may be accelerated or it very could be fossilized within the concrete.
How do we move forward after the initial amount of research that we have gathered ?
Imagine this:
Crystalline structures: Current research shows interest in the possibility of enhancing concrete in a microscopic scale.
What if we were able to replicate such crystalline structures and scaled them to the size of gravel ? As architects we are trained in creating metaphors that are able to transcend various types of scales and proportions. Could this be a design challenge in the sense that the we are "geo-mimicking" speculative forms interpreted from electron scans ? The exercise of extracting the geometry from an image wouldn't be so much different than sketching. The only difference is that it would be a 3D sketch of a crystalline structure.
3D Printing using B-Pet : We know that PolyEthylene Terephthalate is one of the most common used plastics therefore being one of the largest polluters. It could become the single largest source for creating recycled B-Pet filament. The sketched crystalline geometries could be 3d printed with this material, creating a net zero waste scenario in which emissions aren't drastically used and plastic is being removed from the environment.
Testing : Current research has focused on using shredded plastic with a minimum number of examples focusing on the geometric properties that could help concrete bind better; similar to how gravel would help concrete bind. Also, thinking of the thermal properties of plastic, it is also possible to test if any 3d printed volume, embedded within concrete would be able to provide any enhancement to insulating properties.
Concrete Application: Not looking far, the scope of the project could simply stay focused on the minimal applications that current plastic-concrete applications have; that being light weight concrete. The research would focus on creating a series of scenarios in which several geometries are developed in order to be embedded as a whole or in small segments to mimic gravel. The test would be composed of a compression test to visualize how concrete deforms, and if the geometry embedded provides any actual support. Prior to that, samples would be tested for insulating properties, and curation times and fabrication times for processing.
Cement VS Aggregate // Understanding the Difference
Types of Concrete Mixtures
Understanding Crystalline Structures of Minerals // Geometrical Relationships
A scanning electron microscope image of minerals within Roman concrete.
Concrete Curation Process :
Taxonomy of Electron Images of Various Minerals :
Example 1 : Texture Properties Possibly Adaptable for Concrete Bonding
Locality: Morocco
Size: 5 cm x 5 cm x 4 cm
Formula: CaSO4 · 2H2O
Description: Rose-like aggregate of tabular brown gypsum crystals formed by precipitation in (usually) arid desert regions containing trapped sand particles.
Website: http://geology.uaic.ro/muzee/mineralogie/
Concept & 3D-modelling by dr. Andrei Ionut APOPEI
Size: 5 cm x 5 cm x 4 cm
Formula: CaSO4 · 2H2O
Description: Rose-like aggregate of tabular brown gypsum crystals formed by precipitation in (usually) arid desert regions containing trapped sand particles.
Website: http://geology.uaic.ro/muzee/mineralogie/
Concept & 3D-modelling by dr. Andrei Ionut APOPEI
Example 2 : Geometric Similarities
Locality: Roşia Poieni, Romania
FOV: ~8 mm
Formula: FeS2
Description: This is my first contact with macro photogrammetry. There is a lot of space for improvements. The main crystal is ~ 4 mm long and represents a dodecahedron, also known as Pyritohedron. The pyritohedron is an isometric closed crystal form of 12 faces, each an irregular pentagon. It is named after pyrite, which characteristically has this crystal form. Pyrite’s brassy golden color led to it being called “Fool’s gold”, but the name of the pyrite comes from the Greek word pyr meaning “fire” because sparks flew from it when struck with another mineral or metal.
Website: http://geology.uaic.ro/muzee/mineralogie/
Concept & 3D-modelling by dr. Andrei Ionut APOPEI
FOV: ~8 mm
Formula: FeS2
Description: This is my first contact with macro photogrammetry. There is a lot of space for improvements. The main crystal is ~ 4 mm long and represents a dodecahedron, also known as Pyritohedron. The pyritohedron is an isometric closed crystal form of 12 faces, each an irregular pentagon. It is named after pyrite, which characteristically has this crystal form. Pyrite’s brassy golden color led to it being called “Fool’s gold”, but the name of the pyrite comes from the Greek word pyr meaning “fire” because sparks flew from it when struck with another mineral or metal.
Website: http://geology.uaic.ro/muzee/mineralogie/
Concept & 3D-modelling by dr. Andrei Ionut APOPEI