Prefabrication experiments - 489 - 3D Printing - An Onsite Assembly Line

 

Considered for the designed-to-order fabrication of small complex objects in the recent history of additive manufacturing, the technology's translation to building has spawned a large amount of analogous exploration, though mostly linked to marginal prototypes. Precisely depositing a fluid concrete or clay composite layer-over-layer numerically controlled to produce an extruded form is the basic idea of these horizontally textured vertical bearing walls. 

 

Timber beams, steel purlins, or any other type of spanning element can be attached to the walls to cover interior space. Vaulting layers has also been explored and experimented with to produce compressive monomaterial structures. In all cases either a robotic arm, or a gantry type crane carrying a nozzle deposits material according to instructions contained in a 3D model, plotting in x-y directions with the z axis being developed at a relatively slow pace, which allows the material’s adequate consistency to settle and support the next layer. From bus stops to micro dwellings, and even two to three-story collective housing, 3D printing is being promoted as a low-cost alternative to conventional site cast concrete. 

 

The mass-construction archetypes are produced on regular, printed foundations or over a slab on grade. Using these techniques to produce housing implies delivering material and machines on a just-in-time basis using only what is needed, reducing costly and wasteful formwork associated with reinforced concrete construction. 

 

3D printing tehniques and methods are progressing rapidly. Demonstrated for continuous printing of linear objects over a conveyor, the Blackbelt 3d printer is showing what can become an alternative to bearing structures, where beams and other types of dimensional components could be made onsite and then simply bolted together or assembled with mortar in a 3d printed kit-of-parts. Producing complex components can further optimize the technology's use by providing any shape needed to adjust to site conditions. Bringing the required digitally controlled tooling to site points to new potentials in terms of size, scope, and shape as the normal transport criteria that limits sizes and capacities need not apply.

Blackbelt 3D, printing linear objects over a conveyor

Prefabrication experiments - 488 - Modern Dry Masonry for Cleaner Sites

 

Masonry construction is commonly known as a wet construction method. The site-intensive process of laying masonry uses binders, with hydraulic lime being the most common, in which water activates a chemical reaction to harden and bond unit elements (modular or irregular) in an infinite variety of stacking arrangements. Historically, Roman opuses or opera symbolize masonry construction's durability -  some of their compressive shapes still stand thousands of years after they were built. Masonry owes its strength to both the permanent binding and the geometric stacking of elements with width and shape as indicators of performance. Bricks, blocks, and stones, are piled following modular dimensions or distributed informally to fill out walls, and more spectacularly arches, domes or vaults using temporary supports as elements are allowed to bind and cure. 

 

Masonry is associated with on-site messiness as liquid binders are mixed and troweled onsite. Dry masonry, common in contexts lacking resources and knowledge to mix robust binders, was developed as a structural alternative based not on the adhesion between units and mortar, but on how elements are fitted together, intertwined in structural resistant geometries with no binding agents except the units' form and weight. This type of clean/dry masonry construction inspires modern alternatives that relieve intensive site conditions requiring no specialized labour.

 

Three startups, Plaex™, Systeme3™ and Legioblocks^™ all share a renewed interest in simplifying masonry construction by either minimizing or even eliminating messy binders. Each system is manufactured with shapes or profiles designed to stack, interlock and snap together like toy Lego™ bricks. All three systems propose load-bearing walls that support other building elements to span horizontal spans. Systeme3™ for example showcases the use of hollow core slabs supported by precast concrete beams and posts to form an industrialized building system. The skeletal structure is infilled with the interlocking blocks which are then layered or insulated to form single- or multi-layered wall systems. Promoted on their ease of assembly, the three systems also promote new materials that include recycled content. Dry Interlocking also introduces potential disassembly and circularity to contemporary masonry construction. 

left: Plaex™, center: Systeme3™ and right: Legioblocks^™

Prefabrication experiments - 487 - The Architecture of Standardization

Since modernism pioneered new architectural possibilities based on industrial techniques and materials, architects have developed an enigmatic love-hate relationship with industrialized construction. In best cases, they have proposed prototypes ingrained with a capacity for mass production, fashioned from off-the-shelf details in the name of standardization; Iconic, well-known architects presented prefabrication as a model for mass housing. Others have been highly critical and probably one of the reasons prefab has fallen short of attaining the same large-scale successes of manufacturing in other sectors. Reaping prefab's advantages requires deep normalization. As presented in mobile home manufacturing in the United States, or in panelized precast concrete systems of the  Soviet era Gosstroys, production was tuned to economic objectives. This type of mass-produced housing was highly criticized by architects for its reduced design value.

 

Architects have espoused the narrative of standardization without the commitment to standardized design. Repeating a singular extruded curtain wall profile in a building is the type of detailing architects have come to propose as their understanding of standardization. Widespread standardization has been achieved in the building industry demonstrated by every part and piece of a building being catalogued, specified, purchased and delivered with respectable lead times; any big-box hardware retailer depicts this comprehensive normalization.

 

Using made-to-stock ready-to-use components to build a house or building is one of the reasons the fragmented building culture remains a successful albeit inefficient model of production. Contractors buy and deploy these elements without scrutinizing low-design value whereas architects will try to redefine elements arguing for the added value of singular design. This singularity associated with architecture is a complete non-standard approach leading to higher costs and increased production waste. The added value of the architectural design process is vital but must be harmonized and weighed against the required changes in production values and methods to achieve atypical designs. Standardization along with designed for manufacturing efficiencies require a grasp of production to attain scaled replicability and represents the only positive way forward for a stagnating industry. 

Walter Gropius and Konrad Wachsmann's Packaged House