- Scientists at the Swiss Federal Laboratories for Materials Science and Technology (EMPA) said they have developed a super absorbing polymer (SAP) that, when introduced to a concrete mix, resists the flaking, splitting and chipping that normally occurs at high temperatures, Gizmag reported. They’ve applied for a patent for their new process.
- The water in standard concrete vaporizes at high temperatures, causing the resulting pressure to compromise its structural integrity from within, a safety concern when that concrete is used for walls, ceilings or load-bearing pillars, according to Gizmag. Researchers first used polypropylene (PP) fiber to create small tunnels in the concrete to help relieve that pressure but found the amount of fiber necessary to reduce heat also affected the ability of the concrete mix to self-compact.
- Scientists then introduced SAP to the mix after soaking the SAP in water beforehand to make it swell to several times its dry volume. As the concrete mix, with the soaked SAP, set, they drew out the extra water through the porous cement matrix. This caused the SAP to shrink, leaving hollow spaces. These hollow spaces then connected to the small tunnels created by the PP fibers, resulting in a large enough network of spaces to withstand high heat.
The results? When compared with the concrete with PP fibers alone, the SAP-PP concrete, unlike the PP concrete, withstood temperatures of up to 1,852 degrees Fahrenheit from a radiant heater without severe chipping or flaking.
Gizmag noted that self-compacting concrete can minimize construction time, demand less equipment and reduce noise. The product's main downside is its lack of fire resistance. This most recent research development could offer a way to "overcome this," according to Gizmag.
Scientists at Northwestern University in Illinois are also innovating in the field of building materials with their "Martian concrete" product, which they say could be used to build habitable structures on the surface of Mars. The "concrete" formula is made of a 50-50 mix of Martian soil and molten sulphur, and researchers say it is durable and resistant to acid, salt and low temperatures.
Meanwhile, researchers at Cardiff University in Wales have been testing self-healing concrete formulas, and a team at the Self-Assembly Lab at MIT and Gramazio Kohler Research have invented what they call "reversible concrete,” made using only a 3-D printer, rocks and string.