Casting a Topography Technical Development on Reusable Modulus Construction System for Forming a Concrete Topographical Shell Structure
Hailey Peixuan Zhang
Experimental 17 2019-2020 Tutor: Andrew Yau
Environmental Technical Study
Chapter 0
Curved roof and dynamic spatial experience with soft divisions
Content
Chapter 0
Chapter 0 -- INTRODOCTION
Chapter 4 -- FLEXIBLE FORMWORK
-Content page -Project introduction -ETS introduction
Casting Concrete on a Topographical Shell Sitting on a Desert Site with the FLEXIBLE FORMWORK
Chapter 1 -- SHELL.
A Topographical SHELL. -Research - Single curved/ double curved/ topographical shell Design of the topographical shell *Elements Chapter 2 -- CONCRETE
Casting CONCRETE on a Topographical Shell. -Research - Green concrete/ traditional concrete Slumping and steepness limitation Design of panel and grid with limitation of steepness and dimension
Chapter 3 -- DESERT SITE
Casting Concrete on a Topographical Shell Sitting on a DESERT SITE -Research - Construction on desert site Excavation Height difference Waste material
Test: Flexible formwork V1 -Research - flexible formwork proposal The Jig Machine - Flexible formwork V2 Chapter 5 -- CONCLUSION
Chapter 0
Chapter 0
Project introduction ETS introduction -Thesis -Hypothesis -Methodology -Design criteria -Design output Site and backgroud introduction Environmental and technical challenge
Chapter 0
A conceptual drawing of extending topographical shell creating dynamic space. Method related: layering
Chapter 0
Thesis The combined effect of both decertification and urban expansion force the existing population moving to the marginal space. This project aims to provide a public leisure space for the new residents of Pardis, Tehran, Iran, as an interface between the modernism residential towers and the bare land. The space will weave the residential towers together with its topographical shell and provide public service including gathering space, school facilities and other domain to support the new residents’ needs in urban lifestyle.
Project Introduction
Hypothesis
The architecture aims to challenge the existing typology of Tehranian architecture in two aspects. On the ecological aspect, maximising the use of solar power and natural ventilaThe project aims to create a social public space as an interface between residential tion could provide a comfortable public space for multiple activities while easing towers and bare land for the new community moving into this desert-urban mar- the energy pressure on Pardis as the current plan is to transmit electricity from ginal area. The topographical architecture challenges the existing Iranian building Tehran. The architecture would play its role as openings and shading are designed while thermal mass is also taken into consideration through construction matetypologies as the pilling of high rises and excavation of small housing block on mountainous zone would lead to further desertification, as well as restrict people’s rial, thickness and volume. Meanwhile, lowering the height level of construction and designing with existing height differences could slow down the construction activities in cages with solid divisions. caused desertification. On the social aspect, soft division, smooth surface and dynamic space have the potential to release the restriction created by high-rises and cage-like modulus apartments and provide a gathering space with contrast to an individual household. The open markets and parks in old Tehran lifestyle are transmitted and transform to this interface between residential towers and bare land. Methodology The definition of topographical architecture ditches the concept of restricted angularity and straightness. The roof would be cast on a lightweight formwork to form a shell, where it touches the ground on the edge would form the entrance. Design Criteria The project aims to have a capacity of 4000 people during the day time and 6000 during night time as the residents living in 12 housing towers surrounding would be the main target of the space. During day time, the space is occupied by majorly women and children as a school and gathering space and during night time it serves as public space for both gender and pulling the diverse community together. The curved wall meant to create a subtle division of comparably more private and public domain considering the amount of people using the space and the topographical aperture should focus on bringing natural light into the space with a decision of soft or sharp atmosphere. The topographical ceiling and floor would work together with the vertical elements to pull the entire space together and create spatial fluency and dynamic experience in order to minimise the solid division between gender, families and communities. The project should aim to fulfil the needs of residents in surrounding housing towers. Therefore it would potentially last whenever there are existing living communities. Design outcome
Chapter 0
Thesis This project aims to develop a new construction method for modulus concrete casting to form a topographical roof with curvature and large span through the investigation of flexible formwork. The technical aspect of the project will focus on the functioning of the jig, including the fixed stand, the adjustable column to shape the curve panel and the edge beams that decide the joinery of each panel. On the environment side of this project, due to the slumping quality of both traditional concrete with cement and “green” concrete, the limitation of the steepness and scale of one single panel should be considered, hence provide the possibility of casting green concrete on the flexible formwork with a curvature.
ETS Introduction
Hypothesis The flexible formwork provides supports for stretched membrane, working together with a system of flexible edge beams to become a reusable mould for curved concrete panel casting. The shell roof is designed as an overall piece in digital with consideration of strength behaviour acting on different curvature. Modulus is then decided and casting individually on the flexible formwork. The angle and curvature of each panel are designed to make it interlocking by itself. Extra joinery is designed to provide strength when necessary. The project leads by Paul Loh with Melbourne University of the Robotic Fabrication of Doubly Curved Facade System is the main reference. Lars Spuybroek’s concrete mould and ETH’s Amidillo Vault are also taken as case studies.
To construct the new topographical typology, the construction method for thin shell architectural elements (the roof) is needed. Traditional ways of thin-shell concrete construction may not be suitable for the site as the amount of formwork or panel transportation can cause damage to the vulnerable land which leads to further desertification.
Methodology Formwork should be able to be adjusted to various height to make an anti-clastic double curve surface that would allow the membrane to hold the geometry with fewer beams as possible. The formwork is made up by the following part: a) a base holding adjustable columns which could be moved on the desert site to cast in situate on different location. b) individual columns with adjustable height to create a curved surface (point to curve to the surface). c) joinery to fix (or clamp) the stretched membrane. d) edge beam system to adjust the joining of each panel to achieve maximum interlocking (or with support of extra slot joints). The materiality of concrete would be taken into consideration as the texture of the mix takes part in slumping, which restrict the maximum steepness of the curvature. With this consideration, the casting machine can be adjusted to coop with the materiality of green concrete
Design Criteria The testing of the flexible formwork machine should first base on the testing result of concrete slumping to decide the size of the panel and the adjustable height range. The investigation of the machine should focus on the flexibility and should have more than one version of testing physical construct. The use of robotic should be taken into consideration, not in the model but the actual construct.
Design outcome The flexible formwork should provide support of the concrete casting in its limitation of curvature and steepness and be multi-using. Each panel should be self-jointed at 4 edges with the interlocking cast. The topographical shell should be self-support and allow extra weight load with the design of geometry and panel interlocking. The overall consumption of formwork should be reduced compared to traditional formwork and hence more environmentally sustainable.
*Topographical surface: This term is defined as a surface of, relating to, or concerned with the artistic representation of the topography - the curvature is comparably organic and complex to single or double curved surface - but could be broken down into panels with double curves
Chapter 0
Site and backgroud introduction -Environmental and technical challenge Pardis, Tehran, Iran New residential town; no infrastructure; no foundermental social domain to support (or maintain) a urban lifestyle (eg. school, market, park). The existing typology of Tehranian architecture has negative results in two aspects. Ecological-wise, the high rises requires piling while the traditional Iranian housing requires excavation on mountainous areas, and both of the methods leads to desertification. Social-wise, the solid divisions and lack of curation of public space leads to a larger split in the community, especially in gender aspect, which female’s social life is pushed aside. The clash happens on the marginal space as the built environment could not support the complementary needs of the moving-in Iranian communities. On one hand, the built environment of Pardis could not satisfy the complementary urban life as the lack of infrastructure and basic programmes of school, mosque and hospital; on the other hand, the diversity of newcomers with various backgrounds leads to a rise of crime rate while female and children’s public space has been restricted as the site is far away from existing developed public parks or malls. Environmental concern: on desert marginal space ; casting on site with traditional formwork or transporting panels to site requires heavy transportation thus demage the already vulnerable land. The disposal of the large amount of used formwork on site or transported out increases pressure on infrastructure which leads to further desertification. Technical challange: Casting a large span thin shell with topographical curvature. Flexible formwork: How flexible. Curvature: the maximum on steepness to cast, the minimum for a span to hold. Joinery: interlocking and where is the extra joinery reinforcement.
Satellite image of the City of Pardis: highlighted area as selected site, a zone in new residential town.
Chapter 0
House hold of an Iranian family; two bedroom; open kitchen (unusual); semi-open balcony; narrow hall ways.
8 units on 1 floor.
Comparably big communal space - residential not only for sleeping.
110 sqm
Semi-open plan kitchen - unusual design as traditional Iranian families suggest “men in common room and women in kitchen”
Bare sunlight in shared space.
However the kitchen and the communal room are separated from the entrance hall way.
75 sqm
15-storey-height apartment block, with minimum Mosque, market, educational space, playground and hospital for basic living community. Legos inserted on the mountain; the higher it located, the more difficult for electricity, water and gas to get in.
On the outskirts of Parand, a makeshift fruit stall sits next to a billboard depicting Ayatollah Ali Khamenei, the Supreme Leader of Iran. Economic pressures have forced some residents to work as street venders to supplement their income.
Construction going on site. Worker barely could afford the so-called affordable housing they build.
Due to the local climate the thickness of the wall is thicker than NA, EU and EA.
Highway leading to Pardis Technology Park
Highway leading to Tehran and Pardis Old Town.
Oasis
Topograohy of the site, major transportation, building typology, and life ritual.
Chapter 1
Chapter 1 A Topographical SHELL
- Single/ double curved/ topographical shell - Research - Case studies Design of topographical shell Design elements
Chapter 0
A conceptual drawing of extending topographical shell creating dynamic space. Method related: layering
Chapter 1
Surface Analysis
Single curved surface
A single curved surface is also know as a monoclastic surface. This type of surfaces only bend in one direction at a time. In order to constuct a large surface in panels, the curve can be divided into polylines and creates an appoximation of “curved surface”. The radius between each appoximate panels should be large enough to avoid intersection, but also small enough to allow connections.
Chapter 1
Surface Analysis
Double curved surface
The diagram on the left shows a double curved surface. There two type of double curved surface, a) Synclastic curvature and anticlastic curvature. A synclastic curvature is principle curvatures of the same sign, the centre or the curvature are on the same side of the surface. An anticlastic curvature, on the opposite, has the centre of curvature locating on the opposite side of the surface. It can also be sub-divided into an apporximation in order to allow panelling in construction.
Chapter 1
Surface Analysis
Synclastic surface and Anticlastic surface
By changing the diameter of the curve, synclastic surface and anticlastic surface could achieve the variation of complex surface. THIS TS PROJECT IS TRYING TO USE THESE VARIETY TO CREATE THE TOPOGRAPHICAL SURFACE THAT SUITS THE SITE, where topographical surface is defined as a surface of, relating to, or concerned with the artistic representation of the topography - the curvature is comparably organic and complex to single or double curved surface - but could be broken down into panels with double curves
Top: synclastic surface iterations Middle: anticlastic surface iterations Bottom: Multiple
Case Studies
Chapter 1
Summary
TWA Flight Centre; ETH ultra-thin, curved concrete roof prototype; Armadilo Vault; Knit Candela. The first case study focuses on LARGE SCALE shell construction in situ. The second case study focuses on casting thin shell in one piece (instead of panelling). The thickness of the shell and reinforce material is also noticeable. The third case study focuses on the joining of panels. The vault is self-supported by the interlocking panels. The force analysis is worth learning. The forth case study focuses on formwork. By researching the *concrete shell projects, the design of the topographical shell should be considering the scale, the thickness, the steepness and its relationship to the site. *The Armadilo Vault project is a limestone shell project, however, because there is no curce panel casting process envolves, the project is more focusing on the geometry but not materiality. Meanwhile, concrete and limestone are both comparably considered as heavy material(self-weight), therefore it is worth to investigate the shell design.
Chapter 1
Case Study TWA Flight Centre
With the site chosen, Saarinen began to develop a design that would take full advantage of its prominence within Idlewild. He ultimately proposed a symmetrical arrangement of four curved, concrete shell roof segments, the curves of which flowed seamlessly from the piers that supported them. Each of the four roof structures was separated from its neighbors by narrow skylights, with a circular pendant occupying the centerpoint in which all four meet. Thus, the TWA Terminal represents an entirely different approach than the thin concrete shells constructed at the same time. The terminal was built to span a space with a minimum of material. The terminal is a pioneering example of thin-shell construction, consisting of a reinforced concrete shell supported at the corners.
1.Thin-shell structrure 2. Formwork showing edge beam 3.Difficulties pouring the shell at edge beam 4. Formwork showing vertical support
Case Study
Chapter 1
ETH ultra-thin, curved concrete roof prototype
The self-supporting, doubly curved shell roof has multiple layers: the heating and cooling coils and the insulation are installed over the inner concrete layer. A second, exterior layer of the concrete sandwich structure encloses the roof, onto which thin-film photovoltaic cells are installed. Eventually, thanks to the technology and an adaptive solar façade, the residential unit is expected to generate more energy than it consumes. The prototype, which has already been dismantled to make space for future experiments, was 7.5 m high with a surface area of 160 m2 (covering an area in plan of 120 m2). The thickness of the concrete has an average thickness of 5 cm varying between 3 cm along the edges of the roof to 12 cm at the support surfaces. Instead of formwork using non-reusable custom-fabricated timber or milled foam, which would be needed to realise such sophisticated form, the researchers used a net of steel cables stretched into a reusable scaffolding structure. This cable net supported a polymer textile that together functioned as the formwork for the concrete. This not only enabled the researchers to save a great deal on material for construction, they were also able to provide a solution to efficiently realise completely new kinds of design. Another advantage of the flexible formwork solution is that during the concreting of the roof, the area underneath remains unobstructed and thus interior building work can take place at the same time.
Chapter 1
Case Study Armadilo Vault The doubly curved vault consists of 399 individual limestone blocks or voussoirs assembled without mortar or other structural connections. The vault stands in compression and spans a total area of 75 m2 with three linear supports along its boundary and one support in the middle. The structure has a more or less triangular shape in plan. The unsupported edges between the boundary supports create openings that provide access to the space underneath. Located in the centre of the exhibition space, the stone vault spans the central walkway between the two entrances and wraps around the existing columns. The columns penetrate the structure’s surface through two large openings, one of which is partially supported. The voussoir geometry results from the discretisation pattern or tessellation, which determines the stone rows or courses. The exterior surface of the vault is called extrados and the interior intrados. The supports are made of 20 mm thick steel plates, and designed to distribute the weight of the vault as evenly as possible over the floor of the protected building. A system of steel ties connects the steel supports and absorbs the vault’s horizontal thrust. The ties are necessary because no mechanical connections to the floor were allowed. Leaving them exposed shows and emphasises that the stone surface structure would not be stable without them. One voussoir lifted from the stone surface. Note that lifting a stone out of the structure would not be possible in reality because of the registration notches. (a) Flat extrados surface. (b) Doubly ruled, load-transferring surface. (c) Curved surface on intrados, generated with rough-cuts. (d) Registration notch. (e) Planarised, non-load-transferring side surface.
Chapter 1
Case Study KnitCandela The dynamic geometry of KnitCandela’s shell is inspired by the fluidcforms of the colourful traditional dress of Jalisco, Mexico. KnitCrete is an innovative material-saving, labour-reducing an cost-effective formwork system for the casting of doubly curved geometries in concrete. KnitCrete formworks use a custom, 3D-knitted, technical textile as a lightweight, stay-in-place shuttering, coated with a special cement paste to create a rigid mould, and supported by additional falsework elements. such as a tensioned cable-net or bending-active splines. Compared to conventional weaving, knitting minimises the need for cutting patterns to create spatial surfaces, allows for the directional variation of material properties, and simplifies the integration of channels and openings, for example, for the insertion of additional formwork elements, insulation, reinforcements, electrical omponents and technical systems for heating and cooling. The hybrid and ultra-lightweight KnitCrete formworks are easily transportable, reduce the need for additional supporting structure and scaffolding, and simplify the logistics on the construction site. The 50 sq.m. of textile shuttering of KnitCandela’s formwork is comprised of four long strips ranging from 15 m to 26 m in length. Each of the four strips is a seamless, double-layered textile produced as a single piece. Two layers of textile fulfil different tasks. The visible inside is an aesthetic surface that displays a colourful pattern and reveals traces of the supporting cable-net falsework system. The exterior surface fulfils technical requirements by including features for inserting, guiding and controlling the position of additional formwork elements. The pockets created between the two layers as part of the spatial knitting process are inflated using standard modeling balloons. These inflated pockets become cavities in the cast concrete, forming a structurally efficient waffle shell without the need for a complex, wasteful formwork. Pockets located on this exterior side of the textile have different knit densities to control the inflated shape and openings for the insertion of the balloons, enabling cavities of different dimensions to be created with one standard balloon size. The soft, colourful textile interior of KnitCandela’s shell and its hard, concrete exterior is visible from all viewing angles. The textile’s striped pattern expresses the knitting fabrication process and the radial symmetry of the shape. This patterning, along with the simultaneous visibility of the soft interior and the hard exterior of the shell enhances the visitor’s spatial experience and the curvatures of the KnitCandela’s form.
Chapter 1
Design Iteration
The Topographical Shell
The topographical shell is in a pavilion scale (20*20 metre) with a maximum height of 3.3 metre at the edge, forming the main opening. Because of the height difference of the site it locates on, from the lowest point to the highest point, there is a 5 metre height difference. The overall shell is a multiplication of 2 synclastic curved surface and 5 anticlastic surface. In construction process, synclastic curved surface is not suitable for fluid material casting because of the slurring behaviour. Therefore the shell is not casted in one piece considering the scale and geometry. It is divided into 1*1 metre panels and each panel will be casted in situ on the flexible formwork system operating on a rail. When the cast is finished, extra falsework will be required but at minimum quantity.
Ref: Chapham House, Carbon Brief 1: PBL Netherlands Environmental Assessment Agency
Chapter 1
Design Iteration
Elevation
The topographical shell sits on a desert site with significant height difference, which means the edge and corner will not locate at a horizontal plane.(excavation and elevation at specific location is introduced to the ground, however compare to the original site, it is minimal) There is only one corner being cantilived, while the other three is supporting the shell, working with one light column from the highest centre.
Chapter 1
Design Iteration
The Topographical Shell
The diagram on the top show the overall curvature of the shell. In the first place, an uneven grid is considered to make most of the panels anticlastic for construction. However, the efforts of adjusting edge beams and removing panels with difference dimensions from the formwork do not suit the construction situation. Therefore an even grid is developed, then adjust to approximations in digital. The diagram at the buttom reveals the grid of panel. In total of four hundred 1*1metre panel, there are 191 panels that are not anticlastic. Therefore, these panels are generated to approximations of anticlastic panel (in order to apply shotcrete), with the edge remaining (for the panels to meet)
Ref: Chapham House, Carbon Brief 1: PBL Netherlands Environmental Assessment Agency
Chapter 1
Design Iteration
Double curved surface
Although each panel is designed to 1*1 metre from top for cutting purpose, due to the steepness of each panel, the actual surface area has significant difference. The diagram on the top illustrate the surface area of each panel. Panels with max surface areas locate at the edge where the steepest area of the shell occurs.
Chapter 1
Elements
Curved Shell Roof - a organic curvature
The iteration of topographical shell comes from the exaggeration of local topography, where openings and groud contact points are redesigned to form the enclosure. The casted curve canopi is a shell with anticlastic curvature. This element aims to create visual expansion and ectension.
Chapter 1
Elements
Horizontal Element - floor generating direction
Horizontall element: topographical floor Curvature of floor creates divisions without solid boundary.
Chapter 1
Elements
Fat Wall - inhabitable wall with curvature
Vertical element 1: wall Wall is defined as a vertical connection between roof/ ceiling and ground/ floor. As the roof is designed as a topographical shell and the wall is trying to achieve an inhabitable volumn through curvature, the relationship and challenge will be how the wall is connected smoothly from surface (roof) to volumn with thickness.
Chapter 1
Elements
Light Column - Vertical support and natural light generation
Vertical element 2: light column Different from the wall, the light column and the roof have a surface to point relationship. Apart from structural support, the light column also generate visual spotlight by introducing natural light into the enclosure and have strong relationship to the sky.
Conclusion The design of the topographical shell is a multipulation of both synclastic and anticlastic curvature as the variety of curvature will lead to a closer definition of my *Topographical surface. The grid should be an even grid to proceed further construction (cutting the panel off from the formwork). Each panel should be justified to an approximation of anticlastic curved surface (one single anticlastic surface) for concrete casting process. Elements discuss surface to volumn, surface to point relationship between vertical and horizontal elements.
This term is defined as a surface of, relating to, or concerned with the artistic representation of the topography - the curvature is comparably organic and complex to single or double curved surface - but could be broken down into panels with double curves
Chapter 2
Chapter 2 -- CONCRETE
Research
Casting CONCRETE on a Topographical Shell.
-Research Green concrete/ traditional concrete Slumping and steepness limitation Design of panel and grid with limitation of steepness and dimension Test: Traditional concrete with cement slumping Test: Green concrete with aggregate slumping Test: Shotcrete slumping
Chapter 2
Chapter 2
Concrete in Modern Construction Timeline 6500 BC - Syria/ Jordan
The first concrete-like structures were built by the Nabataea traders or Bedouins who occupied and controlled a series of oases and developed a small empire in the regions of southern Syria and northern Jordan in around 6500 BC.
700 BC - Syria/ Jordan They later discovered the advantages of hydraulic lime -- that is, cement that hardens underwater -- and by 700 BC, they were building kilns to supply mortar for the construction of rubble-wall houses, concrete floors, and underground waterproof cisterns. The cisterns were kept secret and were one of the reasons the Nabataea were able to thrive in the desert..
600 BC - Rome By 600 BC, the Greeks had discovered a natural pozzolan material that developed hydraulic properties when mixed with lime, but the Greeks were nowhere near as prolific in building with concrete as the Romans. By 200 BC, the Romans were building very successfully using concrete, but it wasn’t like the concrete we use today. It was not a plastic, flowing material poured into forms, but more like cemented rubble.
1793 - England John Smeaton discovered a more modern method for producing hydraulic lime for cement. He used limestone containing clay that was fired until it turned into clinker, which was then ground it into powder. He used this material in the historic rebuilding of the Eddystone Lighthouse in Cornwall, England.
1824 - England Joseph Aspdin invented Portland cement by burning finely ground chalk and clay in a kiln until the carbon dioxide was removed. It’s widely believed that Aspdin was the first to heat alumina and silica materials to the point of vitrification, resulting in fusion. During vitrification, materials become glass-like. Aspdin refined his method by carefully proportioning limestone and clay, pulverizing them, and then burning the mixture into clinker, which was then ground into finished cement.
1904 - Ohio First concrete highrise building was constructed in Cincinnati, Ohio. It stands 16 stories or 210 feet tall.
1911 - Rome First long span concrete construction, the Risorgimento Bridge was built in Rome. It spans 328 feet.
1921 - Paris two gigantic parabolic-arched airship hangars were built at Orly Airport in Paris. In 1928, a patent for pre-stressed concrete was granted.
Concrete in Modern Construction 1930 Air-entraining agents were developed that greatly increased concrete’s resistance to
freezing and improved its workability. Air entrainment is the use of agents that, when added to concrete during mixing, create many air bubbles that are extremely small and closely spaced, and most of them remain in the hardened concrete. Concrete hardens through a chemical process called hydration.
~Same period of time THIN-SHELL Expertise in building with reinforced concrete eventually allowed the development of a new way of building with concrete; the thin-shell technique involves building structures, such as roofs, with a relatively thin shell of concrete. Domes, arches and compound curves are typically built with this method, since they are naturally strong shapes. In 1930, the Spanish engineer Eduardo Torroja designed a low-rise dome for the market at Algeciras, with a 3½-inch thickness that spanned 150 feet. Steel cables were used to form a tension ring.
1935 - Hoover Dam The Hoover Dam was completed after pouring approximately 3,250,000 yards of concrete, with an additional 1,110,000 yards used in the power plant and other dam-related structures. Engineers for the Bureau of Reclamation calculated that if the concrete was placed in a single, monolithic pour, the dam would take 125 years to cool, and stresses from the heat produced and the contraction that takes place as concrete cures would cause the structure to crack and crumble. The solution was to pour the dam in a series of blocks that formed columns, with some blocks as large as 50 feet square and 5 feet high.
2011 - Dubai The world’s tallest structure (as of 2011) was built using reinforced concrete. The Burj Khalifa in Dubai in the United Arab Emirates (UAE) stands 2,717 feet tall.
Chapter 2
Concrete and its Enviornmental Impact
CO2 EMISSIONS:
Image: Portland cement kiln
Eight to 10 percent of the world’s total CO2 emissions come from manufacturing cement. The global warming gas is released when limestone and clays are crushed and heated to high temperatures. 1In 2016, world cement production generated around 2.2 billion tonnes of CO2 - equivalent to 8% of the global total. More than half of that came from the calcination process. Cement making process 1. Raw materials, mainly limestone and clay, are quarried and crushed 2. They are ground and mixed with other materials - such as iron ore or ash 3. They are fed into huge, cylindrical kilns and heated to about 1,450C (2,640F) 4. The process of “calcination” splits the material into calcium oxide and CO2 5. A new substance called CLINKER emerges as marble-sized grey balls 6. The clinker is cooled, ground and mixed with gypsum and limestone 7. The cement is transported to ready-mix concrete companies Image: Portland cement clinker
Heat CaO + CO2 CaCO3 --------> Ref: Chapham House, Carbon Brief 1: PBL Netherlands Environmental Assessment Agency
Chapter 2
Concrete and Environmenral Impact
Ground Granulated Blast-furnace Slag (GGBS) GGBS is a by-product of the iron and steel industry. In the blast furnace, slag floats to the top of the iron and removed. GGBS is produced through quenching the molten slag in water and then grinding it into a fine powder. Chemically it is similar to, but less reactive than, Portland cement (Pc).
Pulverised Fuel Ash (PFA) (Fly Ash) PFA is a by-product of coal-burning power stations. In the future, as coal-burning power stations are phased out, PFA will gradually become unavailable.
Others including silica fume, alternative fuels and limestone fines could be considered as cement substitute. However may not be suitable for the site of Pardis, Iran.
GREEN CONCRETE GREEN CONCRETE is defined as a concrete which uses waste material as at least one of its components, or its production process does not lead to environmental destruction, or it has high performance and life cycle sustainability. One of the major effort is made on how to replace traditional cement with green aggregate. Various efforts have been conducted by researchers to arrive at some alternatives that are able to significantly reduce high energy consumed and environmental impacts during fabrication process of cement, including implementing the concept of industrial ecology and green chemistry as well as nanoengineering that study the behavior of the structure and organization of nanoparticles of cement in the mix for achieving higher performance. The cleaner technologies in concrete production, such as substituting relatively high percentage of cement by FLY ASH (up to 100%), the use of other natural pozzolans, development of concrete with recycling or waste materials, and developing nanoconcrete by integrating CNT’s or self-sensing CNT’s in the concrete mix for higher performance in terms of strength, stiffness, and durability.
Chapter 2
Concrete Slump Testing
The slumping range of traditional concrete with cement, shotcrete and green concrete is different, hence leads to the limitation of applying on a topographical shell (a surface with organic curvature). Considering the environmental impact of cement, the aim of this project is to use as less traditional concrete as possible. Physical testing procedure might have different results to theoratical statistics. Below are processes of the concrete slump test. 1. Find a flat and level surface. 2. Clean and dampen the table surface and cone. 3. Place the cone in the middle of the table, and secure it in place. 4. Fill about a third of the cone with the first layer of shotcrete, then tamp 25 times with the tamping rod. 5. Repeat with the second and third layers. 6. Use tamping bar to ‘skim off’ any extra shotcrete, leveling it with the top of the cone. Clean off any spillage. 7. Carefully lift up the mould, making sure the concrete is not subject to any twisting or lateral movements. 8. Measure the height difference between the highest point of the slump and the top of the cone. 9. The test should be carried out within a timeframe of 150 seconds from start to finish.
Software: CFDEM(LIGGGHTS) Liquid Bridge model was used for the cement effects between concrete particles. Simulation results showed a good agreement with the experiment data.
Source: CAE-Garden, http://cae-garden.com/?p=941, 2020-01-06
Chapter 2
Concrete Slump Testing
4 groups of testing should be done, including: G1: Traditional concrete cement mixture G2: Water/ sharpsand/ cement remains same quantity as G1; add nylon fibre for strength. G3: Water/ sharpsand remains same quantity as G1; replace traditional cement with recycle aggregate (crushed asphalt or concrete from old construction) . G4:Water/ sharpsand/ recycle aggregate remains same quantity as G3; add nylon fibre for strength. G5: Traditional 1 part cement and four parts sand by weight with approximately 7% water by mass of dry ingredients.
According to European Committee for Standardisation (CEN), “Testing Fresh Concrete: Part 2: Slump Test”, Published 2009, below are the typical slump range of concrete.
Chapter 2
Casting on Curved Surface - Plaster Test
Plaster comparably similar to concrete - fluidity Plaster, when ready mixed and apply, is much more fluid than concrete. Therefore the material applying method is different. Plaster is more similar to liquid pouring, when significant curvature occur, it is difficult to stop it slurring from the surface unless a top mould is added. The plaster test is casted on a rigid formwork, with timber beams that define the geometry as the supporting structure. Fabric is then stretched on and solidified with resin. Rigid edge beam is added along the curve of the canopi to stop it slurring. The result is not as satisfied. a) In order to prevent slurring, the plaster mix is thicker than the right range, which lead to a more fragile cast and cause the difficulty of removing. b) The plaster is still slurring significantly, therefore it has an uneven thickness and thicker than expectation. c) Cast product does not have a smooth surface. d) The shell is not self supporting - extra “column” is added. e) Edge is clumsy as the edge beam is not designed but “attached”.
When casting concrete on steep surface, spreading could be one of the method to due with uneven surface, as concrete is more similare to a paste. If concrete could not stop slurring at certain degree of steepness, shotcrete could be apply with high pressure nozzle and then spread on the surface (reinforecement needed).
Chapter 2
Casting on Curved Surface - Plaster Test
Chapter 2
Casting on Curved Surface
Concrete mixture: 1 part cement; 2 part sharp sand; 10g nylon fibre Normal concrete mixture is not sticky enough for a concrete spreading process on a curved surface. Nylon fibre is added to increase strength of the material mixture. Mould: stretched fabric on metal wire frame, solidified with plaster polymer. Due to the strength of the frame is not strong enough to hold the tension of fabric and the weight of plaster and plaster polymer, the geometry deformed slightly on the edges.
Chapter 2
Casting on Curved Surface
There is on aperture in the casting experiment, in order to test the edge condition. Edge beam with a consistant height was attatched to the edge. However from the result it is revealed that the concrete edge is not as even as it should be due to the uneven mixture and the portion of nylon fibre. The concrete slumps more on a steeper surface, which make the edge goes thicker. Obvious cracks reveal on the result due to the portion of water is less than what is needed.
The amount of nylon fibre is way more than the correct portion as it should not be seen on the product surface. Nylon fibre is added in order to help applying a considerably more fluid concrete on a curved surface. Considering the scale of the test and industrial application process (high pressure nozzle), the application of the test, which is applying concrete with spreading technic is not the most relatable way.
Conclusion less than 30-degree slope--2- to 4-inch slump 30- to 45-degree slope--1- to 3-inch slump more than 45-degree slope--double forming may be considered for concrete thickness of about 6 inches or more [or shotcrete should be used]
Chapter 1
Chapter 3
Research
Casting Concrete on a Topographical Shell Sitting on a DESERT SITE
-Construction on desert site Case study -Buhais Geology Interpretive Centre (elevated) -Aloni House (excavated) Site - Pardis, Tehran, Iran Design iterations Excavation Height difference Waste material (1. metal frame by product. 2. excavated sand/ stone)
Chapter 1
Chapter 3
Case study 1
Buhais Geology Park Interpretive Centre Sharjah, United Arab Emirates. Hopkins Arcbitects
Desert - Architecture relationship: minimised contact with the ground. (Lifted, minimal excavation) The project site features an abundance of marine fossils from over 65 million years ago, spectacular mountain ranges and ancient burial sites from the Stone, Bronze and Iron Ages. According to the architect, to build these structures, they aimed to intervene the geological terrain as minimum as possible. An outdoor, sinuous looping trail links the pods together. Construction is arrayed from the ground. The structures is designed as pre-fabricated concrete structures and only lightly touch the ground on in-situ reinforced concrete foundation discs. There are 6 pods in total to make the whole centre, including exhibition areas, an immersive theatre, a cafe, a gift shop and other visitor facilities. 1 pod is situated separately to serve as a serving buildng. Considering the solar radiation and temperature in desert, this architecture requires modern technology in ventilation, cladding and air-conditioning. Traditional desert architecture use the thickness of the wall or bury themselves in to the soil to get natural ventilation from the site, however, this architecture does not involve excavation or underground construction.
Ref: Chapham House, Carbon Brief 1: PBL Netherlands Environmental Assessment Agency
Chapter 3
Case Study 2
Aloni House
Antiparos, Greece decaArchitecture
Desert - Architecture relationship: Half-burried This residential project is a dual response to the particular topography of the site and to the rural domestication techniques that in the past shaped the raw ‘Cycladic island’ landscape. The site is a natural saddle where two slopes meet.
Although the design is located in the lower part of the site, excavation is still the main way to treat the landscape, including carving out the couryards and the foundation for the stone wall.
Ecological-wise the construction is using local material to achieve a lower energy consumpsion, including 2 rural stone wall which become the main structural support and retaining wall from the surrounding earth. In terms of ventilation, the Aloni house nestled in the valley between two hillsides takes advantage of cross-winds as well as the cooling effects of a green roof.
Chapter 3
Pardis, Iran
Existing architectural typology: Residential high rises - social housing. Environmental impact: excavation for foundation - demage desert landscape; building waste from excavation - taking space of bare land. Social impact: Lack of social space to form an urban lifestyle. (eg. playground, school, park, etc)
Detail research in Chapter 0
Chapter 3
City Axo
House hold of an Iranian family; two bedroom; open kitchen (unusual); semi-open balcony; narrow hall ways.
8 units on 1 floor.
Comparably big communal space - residential not only for sleeping.
110 sqm
Semi-open plan kitchen - unusual design as traditional Iranian families suggest “men in common room and women in kitchen”
Bare sunlight in shared space.
However the kitchen and the communal room are separated from the entrance hall way.
75 sqm
15-storey-height apartment block, with minimum Mosque, market, educational space, playground and hospital for basic living community. Legos inserted on the mountain; the higher it located, the more difficult for electricity, water and gas to get in.
On the outskirts of Parand, a makeshift fruit stall sits next to a billboard depicting Ayatollah Ali Khamenei, the Supreme Leader of Iran. Economic pressures have forced some residents to work as street venders to supplement their income.
Construction going on site. Worker barely could afford the so-called affordable housing they build.
Due to the local climate the thickness of the wall is thicker than NA, EU and EA.
Highway leading to Pardis Technology Park
Highway leading to Tehran and Pardis Old Town.
Oasis
Chapter 3
City Plan
The architecture sits on a desert ground, surrounding by a series of residential towers, but not touching the existing building. The height difference allows the shell lands at different height at each corner.
Chapter 3
Site Axo
The surrounding residential towers are approx. 60 metres tall, which is a lot taller than the proposing topographical shell architecture.
Chapter 3
Design Iterations
The physical constructs from studio design may not be all strongly related to the final design, however, they reveals the attitute toward treating the desert, which is using the existing height difference and minimise excavation to protect the already volnerable desert landscape.
-Boundary between Desert and TownExperimentation 2R Hailey Peixuan Zhang
-Desert ConstructExperimentation 3R Hailey Peixuan Zhang
Chapter 3
Design Iterations
Physical Construct V4 Hailey Peixuan Zhang
Merging in the ground with a smooth slope.
Neither of the design requires deep foundation or excavation.
Floating on the ground.(Hub/ Cabin)
Chapter 3
Pardis - Issues
CONSTRUCTION Petrol cannot be imported, so the shortfall is being made up by converting petro-chemical plants – but their product is lowgrade and produces toxic fumes, adding to the clouds of smog that so often hide the mountains just to the north of the capital. “Why is the world so worried about us being able to make a nuclear bomb,” asked one Iranian sarcastically, “when we cannot even build proper refineries to make petrol?” HOUSING Official figures are hard to come by, but a recent parliamentary report suggested that people are being pushed out of larger cities by the rising cost of living. The “rise in cost of sales and rents in big cities, especially Tehran, has increased movement to the satellite towns . . . which could lead to social crises”, the report said. At least 1m people moved out of big cities last year because of economic hardship, said Ali Kord, a member of parliament. The impact of the crisis has been clear in towns such as Parand, where hundreds of new flats were built in recent decades and arrivals from Tehran have become a regular sight. While Parand may be cheaper, poor infrastructure — it takes two hours to travel to central Tehran — and a lack of greenery had made it an unattractive place to live. With little in the way of cinemas, gyms or even parks to entertain jobless youth, some residents fear a rise in social problems. “The youth have no gyms or parks to go in Parand while it is now opening doors to people who feel desperate,” said the owner of a grocer’s shop, who did not want his name to be published. “Young men in this town find refuge in drugs, violence and sitting idly out in the streets.”
Conclusion Deep excavation is not encouraged. Case study 1’s railing system could be adapt to design and construcion. Shallow foundation is needed as the design is not an individual hub but smoothly emerging with the groud. Height difference provides possiblity of different spatial experience.
Chapter 2
Chapter 4
Test: Flexible formwork V1
Casting Concrete on a Topographical Shell Sitting on a De- -Research - flexible formwork proposal sert Site with the FLEXIBLE FORMWORK
The Jig Machine - Flexible formwork V2
Chapter 12
Test
Flexible Formwork for Casting Version 1
Flexible formwork for stretched fabric. Curved was not defined when the test was made therefore extra support eg. wire is added for geometry holding.
Chapter 4
Flexible Formwork V1
Details and measurement
Chapter 4
Flexible Formwork 1
Multiple height column system
Geometry is design digitally, then tranlate to the height of each column. Cons: a)Timber is not a good material for a flexible formwork as its work life is quite short - after on test the column system is already wobbling. Also it is not strong enough to hold the tension of the fabric and steel wire, which lead to the shrinking of the edge. b)There is better way to do the height scale: Current method: [drill, screw-drill nails in, screw-drill out, sand off half of the timber to expose nail column, attach transparent measurement with nails} is not easy to adjust the height and takes a lot of time. c)The fabric cannot hold itself only on the end of the columns - even with steel wire to create a network of beams, due to the geometry, it still will not achieve a smooth surface. d)Edge condition not solve. Edgebeam is not flexible.
Flexible formwork for stretched fabric. Curved was not defined when the test was made therefore extra support eg. wire is added for geometry holding.
Chapter 4
Flexible Formwork 1
Rigid formwork
Plaster polymer is apply on the stretched fabric for 3 layers. (Plaster polymer: plaster = 1:1) The mixture will solidify the fabric in tension. Reinforcing steel wire is not remove in this experiment. However the outcome is strong enough to hold the concrete even without steel wire. Aperture is carved out after the formwork is solidified. However it should be left out at fabric stage and maintain in shape with an edge beam.
Chapter 4
Case study 1
ROBOTIC FABRICATION OF DOUBLY CURVED FAÇADE SYSTEM Paul Loh, University of Melbourne; DAVID LEGGETT, Architectural Research Laboratory; DANIEL PROHASKY, Swinburne University of Technology
A: Axis rotatory table B: MDF based frame C: Horizontal lead screw D: Vertical lead screw E: Stepper motor F: 3D printed end stop G: Acrylic tray H: Casted concrete panel J: Kuka robotic arm K: Centre treaded rod Function: The flexible jig consists of an MDF base frame that is fixed to the axis rotary table associated with the Kuka robotic arm. The base supports four sets of actuators, each consisting of a vertical leadscrew and a horizontal leadscrew driven by a stepper motor . The end of the vertical leadscrew is fitted with a 3d-printed end stop on which the casted concrete panel [H] will rest. An acrylic tray over the base frame collects and drains the water from the cutting process. The concrete panel is cast with an cast-in threaded inserts as close to the centre point on the back face of the panel which is screw fixed to the centre threaded rod. The centre point is an important reference point as it is the only common point among the variably shaped panels. The skew and beta data are converted to travel distance, and the armatures is moved into position of the panel’s corners. The position of the panel is not entirely accurate due to factors such as the varied thickness to the panel’s back face and achieving full contact with the end stop; misalignment will cause a tilt in the panel position. This will result in an accumulative error if panels are to be butt jointed to produce a seamless surface.
Loh, P., Leggett, D. and Prohasky, D., 2020. Robotic Fabrication Of Doubly Curved Façade System: Constructing Intelligence In The Digital Fabrication Workflow. [online] Hdl.handle.net. Available at: <http://hdl.handle.net/11343/233218>.
Chapter 4
Case Study 2
Flexible Mould
Conceptual diagram, Renzo Piano
Sketch and details of a flexible mould by Renzo Piano. One of the first to describe a method for production of double curved elements. [Piano, 1969] Each panel is approximately 2 * 1.5 metre, which the size allows hand applying of concrete(when robotic arm was not as developed as today). The cast is not insitu on site, instead, the flexible formwork is for mass production of double curved concrete panels. Although not all researchers use an elastic material as intermediate layer between actuators and concrete, the casting of concrete almost inevitably requires some kind of formwork layer.
Schipper, Roel & Janssen, Bas. (2016). Curving Concrete–A Method for Manufacturing Double Curved Precast Concrete Panels using a Flexible Mould.
Chapter 4
Flexible Formwork 2
General discription
Flexible formwork V2 is a set of 25 adjustable columns drive by servo engine, sitting on a trolley-like base which moves in the direction of the rails. The light weight rails are pre-constructed on the site following the height differences and existing topography. Workers control the power of each motor link to the column remotely and according to the digital design of each panel. Power affects the spining of motor hence define the height of each corkscrew column. Light-weight rigid edge beam is pre-fabricated for local industry (Pardis old town), then clamp to the columns. Reinforcing bars weave through the pin hold of the edge beam and follows the height of each adjustable column unit. Steel cable net is then stretched on for fabric to be stretched on and become the formwork, with second layer flexible reinforcement. Shotcrete is applied with high pressure nozzle, then spread out evenly to create a smooth surface by hand. The panel is cut out (including reinforce bar) by robotic arms vertically. The edge is then sanded/ cut for each panel to meet. Panel is casted in situ, therefore extra falsework is needed.
Robotic arm
Second reinforce
Steel cabel net + fabric
Steel bar reinforce
Light weight edge beam
Clamp
Corkscrew
Column Motor/ Servo engine Trolley-base
Rail
Chapter 4
Addjustable Formwork
Servo engine, motor and corkscrew column system
Servo engine - motor - column
Chapter 4
Addjustable Formwork
Clamp. edge support, edge beam and reinforcement
Steel cable net
Chapter 4
Flexible Formwork 2
Transformation
Conclusion Further consideration edge treatmeant should be developed, as now the panels are relying on extra edge reinforcement. The edge beam is now rigid and prefabricated. There are possibilities to develop a chai-like flexible edge beam to reduce material waste. Should the casting be in situ? - as the falsework requires more material and in situ casting leads to unneccesary tilted steepness, which increase the difficulty of casting. If the panels are pre-fabricated, the productivity of flexible formwork maybe slower than factory work/ casting in one piece.
End