New and Emerging Materials Dale Fenton
Plastic Structural Members While current use of polymers is reduced to non-structural applications there are advances with some high-density polymers that provide sufficient strength for use in structural superstructures and eventually in highly plastic structural shapes. Some of these plastics have the benefit of being fire-resistant, and nonreactive with the environment once in place. Some uses of high-density plastics can currently be seen in transmission towers and lightweight bridges. Plastic formed “lumber” is also available and while it is only currently available in standard sizes could be produced into more organic and fluid forms for exterior applications where resistance to rotting is desired.
Plastic Structural Adhesives Great advances are being made in the strength and durability of polymer adhesives. While many are currently used for sealants and construction adhesives there is hope that at some point these adhesives may be strong and versatile enough to essentially “glue” disparate building modules together in strong, durable structurally sound bonds so that mechanical fasteners could be avoided. Current structural adhesives are based on epoxy, acrylic or polyurethane chemistry. In the future there may be adhesives capable of providing structural bonds similar to welds between different materials such as metals, plastics, wood, and glass.
High-Tech Concrete There is significant research into new types of concrete with varying properties. The most promising advancements are in ductile concrete which has increased strength in compression compared to normal concrete, but also can accept significant tensile stresses making it appropriate for creating complex forms without the need to incorporate reinforcing steel because the mixture uses small aggregate and includes fiber reinforcing from carbon-fiber, glass fiber or other high-tensile strength materials.
Smart Materials Smart Materials include a broad category of newly developing substances and composites with incredible properties. Some of these are: Piezoelectric: materials that produce a voltage when stress is applied Shape memory materials: can be deformed and returned to their original shape Self-healing materials: can repair damage to themselves Other types of materials respond to changes in: magnetic fields, pH differences, temperature, light, or other external stimuli.
Aerogel An extremely lightweight, manufactured material derived from a gel where the liquid component is replaced with gas through supercritical drying. Impressive load bearing capabilities Dendritic microstructure spherical particles 2-5 nm fused together in clusters 99% air Friable current structures easily shattered with enough force Good thermal insulators nullifies convection, conduction, and radiation Types of Aerogel Silica lowest density solid 1mg/cm3 absorbs solar radiation, traps heat extremely low thermal conductivity 0.03 W/mk to 0.004 W/mk currently used aboard Stardust spacecrafts to trap space dust Carbon can be electrically conductive, depending on density absorbs infrared radiation
Alumina SEAgel made of agar, substance derived from kelp or red algae currently used in time-release medical pills and sound damping for trains Possible Uses in Architecture Structure good load-bearing capabilities Insulation Aerogel lattice traps air poor conductor of heat absorbs solar radiation Windows
Carbon Nanotubes A form of carbon with a cylindrical nanostructure. Belongs to Fullerene structural family Strong tensile strength due to “covalent sp2 bonds between individual carbon atoms” specific strength up to 48,000 kN·m·kg−1 high-carbon steel 154 kN·m·kg−1 Weak in compression Low density solid 1.3 to 1.4 g·cm−3 Length to diameter ratio 132,000,000 : 1 1/50,000th width of human hair up to 18 cm long Efficient thermal conductor Current applications Carbon nanotubes currently used is fragmented masses Used as composite fibers in polymers Zyvex Performance Materials bicycle components, lightweight boat 8,000 lbs underwater sonar speakers
Kevlar A lightweight, synthetic fiber spun from liquid crystalline solution. Manufactured by DuPont High tensile strength, light weight 5x stronger than steel Range of products Pulp, fiber, paper, felt Body armor, military uses Storm shelter DuPont Storm Shelter anchored in ground with concrete resists wind and gusts up to 250 mi/hr integrated with house includes wiring and plumbing
Spider Silk “High performance fibres from natural or artificial proteins based on the principles used by spiders and insects to create natural silk fibres” 6x stronger than steel 5x stronger than Kevlar Manufactured by Spinox current devices produces silk 4x thicker (15 microns ) than natural spider silk High strength to weight ratio Strong in tension stretches 140% of length without breaking Current applications Sutures, tissue replacement, bone and joint repair Currently difficult to mass produce spiders squirt out thick gel solution, use body weight and gravity to elongate into fibers alignment of protein fibers give strength Genetically engineered silkworms
Sources: Transmaterial : a catalog of materials that redefine our physical environment / edited by Blaine E. Brownell. New York : Princeton Architectural Press, c2006 High-performance construction materials : science and applications / editors, Caijun Shi, Y.L. Mo. Singapore ; Hackensack, NJ : World Scientific, 2008 Materials for the third millennium / editors, R.K. Ray ... [et al.] Enfield, NH, USA : Science Publishers, c2001 Material architecture : emergent materials for innovative buildings and ecological construction / John Fernandez Boston : Architectural Press, c2006