Prof. A’s Tedx Talk: Designing for strength, economy and beauty

  Check out this video and like it on YouTube. By 2050, 70% of the world’s population will live in cities. Structural engineers envision, design and construct the bridges and long‐span buildings those city dwellers depend on daily. The construction industry is one of most resource‐intensive sectors, and yet our urban infrastructure continues to be built in the massive tradition in which strength is pursued … Continue reading Prof. A’s Tedx Talk: Designing for strength, economy and beauty

Our Summer Rammed Earth Experiments 2/3: Construction of swirling rammed earth wall

Before the large swirling structure in Forbes garden could be constructed, a set of tests walls were built to master the construction workflow. The tests walls will also be used to test a different set of erosion protection measures, as one of the goals of our research experiment is to assess the erosion resistance of rammed earth in New Jersey. The first test wall was built out of unstabilized earth with no erosion protection implemented for reference. The second wall was also unstabilized, but plants will be grown on top of this wall in the hope that their roots will slow down the erosion process, while their leafs protect the dirt from driving rain. The third test wall was stabilized on the outside with a 10% lime-earth mixture, which was applied only at the outer 3 cm. This technique is a traditional rammed earth construction technique originating in Spain and referred to as “calicascado” which can be freely translated as “lime shell”. The 4th and final test wall was built unstabilized earth once again again, but half of it was coated using a silicone spray, while the other half was coated with a lime wash. All of the test walls were built with a reusable plywood formwork on top of a blue stone slab..

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Scheme of the test walls
Rammed earth test walls. Both left walls are unstabilized, the wall still in the formwork was built using the calicascado technique.

After the successful completion of the test walls, we moved on to the much larger spiraling wall inside Forbes garden. As explained in the previous blog post, the spiral consists of a lower bench area and a taller wall, separated by an opening. At its lowest point the bench is 40 centimeters high, and at its highest point it is 3 meters tall. Both rest on a blue stone foundation. Again, different erosion-protection measures were implemented. The bottom 15 cm of the entire wall was made out of a 25% lime- earth mixture, and placed on a water impermeable membrane to avoid capillary rise. The outside of the bench and most of the rest of the spiraling wall was stabilized using the calicascado technique after its promising results on the test walls. A great advantage of this technique is that it allows for a minimum volume of soil that needs to be stabilized with lime and thus requires less material transport. To compare the durability of the technique once again a section was left unprotected. Additionally, one section of the wall was entirely lime-stabilized using 6% lime as an extra test.

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Our Summer Rammed Earth Experiments 1/3: The Golden Spiral for Forbes Garden


Dirt—as in clay, gravel, sand, silt, soil, loam, mud—is everywhere. The ground we walk on and grow crops in also happens to be one of the most widely used construction material worldwide. Earth does not generate CO2 emissions in its generation, transport, assembly or recycling and this in contrast to more conventional building materials such as concrete and steel. In rammed earth construction a mixture of  clay, silt, sand and gravel is compressed into a formwork to create a solid low-cost load-bearing wall. Despite the renewed architectural interest in contemporary rammed earth construction in (semi-)arid climates of the USA, little is known about its potential in the erosive humid continental climate of New Jersey. Because of the great potential of rammed earth as a local building material, we decided to design and construct a spiral rammed earth structure in Forbes Garden that will be an enduring representation of Princeton’s effort to create a campus containing sustainable and elegant zero carbon architecture.

The Material:  Dirt

The Form Finding Lab’s team established the suitability of Princeton soil for earth construction though an extensive set of laboratory tests. The team, led by PhD candidate Tim Michiels and supported by undergraduate student Amber Lin ’19 and summer intern Jacob Essig, subjected a series of compacted samples with different water contents to compression tests (the rammed earth samples had an average compressive strength of 1.35 MPa). The team also experimented with lime additives  (3%, 5%, 10%, and 25%)  to test the compacted dirt’s resistance to weathering on a series of prototype walls (See image above title).  All these results informed the design of the structure that was designed for Forbes Garden as part of the Campus as Lab Initiative .

Testing of compacted samples with different dirt compositions to establish unconfined compressive strength. The local soil was composed of 19% gravel, 42% sand, 24% silt and 15% clay.

The Site: Princeton Garden Project

The Princeton Garden Project at Forbes College is a student led initiative that supports and advances sustainability and food awareness  on Campus. Following with its mission of sustainability, the rammed earth spiral is a sustainable experiment made with local and abundantly available materials intended to enhance the existing organic garden and transform it into a space for research and learning.

The Garden Project, the ideal collaborator for a rammed earth project (image credit Garden Project at Forbes College)

The Design:  A Site-Specific Golden Spiral

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Design-and-build bamboo shells

Bamboo is a building material that lends itself excellently to the construction of sustainable gridshells. Two of the Form Finding Lab’s graduating senior students, Lu Lu and Russell Archer (’16), worked under the guidance of PhD candidate Tim Michiels and Professor Adriaenssens on the analysis of a set of hyperbolic paraboloid (hypar) gridshell roofs in Cali, Colombia. The Form Finding Lab’s team collaborated closely with … Continue reading Design-and-build bamboo shells

What I Am Thinking: Biologist-Turned-Architect Doris Kim Sung Makes Buildings Breathe

During my Art Residency  in Bellagio, Italy, I had the privilege of interviewing USC Architecture Professor and Princeton alumna Doris Kim Sung. In her work, Doris interprets architecture as an extension of the body and explores how buildings can passively adapt to their environment through self-ventilation and shading by using smart materials and design. 

Russell Fortmeyer, Doris Kim Sung and Sigrid Adriaenssens in conversation in Bellagio, Italy.

Sigrid Adriaenssens: What are the research questions that your designs address?

Doris Kim Sung: Can the geometry or the unit design of a smart material such as thermobimetal affect the architectural performance of a larger tessellated surface intended to shade, ventilate, stiffen, or propel? 

What is “unplugged” architecture? Can you exemplify that concept with one of your projects?

This reference from rock or pop music means without electronic amplification or disconnected from the world of gadgets. I have a deep-seated interest in finding solutions that don’t require added electrical energy or computer controls. For this reason, I have been working with smart materials such as thermobimetal, a material that reacts to heat (it curls), and developing for building use (for auto shading and ventilation in “Bloom”) and construction techniques (for one-hand/one-person assembly systems). Because the use of the material does not require energy, it is a “passive” type of system, but the responsive nature of the material to the sun and ambient temperature make it surprisingly active.

What can you tell us about your latest innovative project?

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Ash wood – catastrophe or opportunity for creativity?

Since 2002, the emerald ash bore beetle, Agrilus planipennis, has destroyed more than 20 million ash trees in the US, with only 30% of the waste timber recycled into low-end products such as mulch and firewood. High value uses could turn this “waste” material into a valuable resource and an economic opportunity, especially considering that, before the widespread development of plastics, aluminum, and carbon fiber, … Continue reading Ash wood – catastrophe or opportunity for creativity?