CompositesWorld
Issue link: https://cw.epubxp.com/i/576646
CompositesWorld.com 69 NEWS N E W S N S N E W S E N W S W Basalt-reinforced Rebar for FHSUs Pervious concrete is fairly porous. Tanks to use of the chunky aggregate that creates pores in its fnished struc- ture, it's often used in parking lots of green buildings to encourage rainwater to infl- trate soils rather than run of to overloaded storm drains. Te biologist already knew that pervious concrete's pores help to clean water by trapping large particles (mechanical fltra- tion) and by providing habitat for microbes and invertebrate colonies, which eat organic matter (chemical fltration) and, in turn, are eaten by fsh fry (baby fsh) and larger vertebrates. Te pores also would help reduce the structure's mass. Because the FHSUs were intended as permanent installa- tions, that's where composites entered the picture. In an aquatic environment, steel rebar would quickly rust and contribute to premature unit failure, but Lutey knew composite rebar would resist corrosion and withstand long-term underwater exposure to freeze/thaw cycles. To fnd a source of composite rebar, Lutey turned to Dr. Mohsen Issa, Ph.D., P.E., S.E., professor of struc- tural and civil engineering at the University of Illinois – Chicago, who is well known for his work on high-performance concrete and rapid bridge replacement. Issa put Lutey in touch with RockWerk Systems Inc. (Naperville, IL, US), which was working with composites consultancy Allied Composite Technologies LLC (ACT, Rochester Hills, MI, US) to develop North American- produced basalt-reinforced composite rebar. "We've been working with Dr. Issa for about 10 years on diferent types of basalt rebar," explains RockWerks partner, Jack Rigsby. "I brought the frst composite rebar over from Russia 12 years ago when I was head of R&D; at Dukane Precast [Naperville, IL, US]. Dukane built the frst building in the US I'm aware of that was reinforced in key sections with basalt rebar for Argonne National Laboratory [Lemont, IL, US]. Tey needed a building free of steel because their equipment created magnetic felds around Rebar reinforced with basalt fiber The FHSUs, afectionately called "catfsh houses," were formed by Urban Habitat Chicago crews using Ozinga's Filtercrete pervious concrete reinforced with composite rebar (unsaturated polyester resin reinforced with basalt rovings supplied by RockWerk Systems Inc.). The project also helped at-risk and disadvan- taged Chicago youth gain useful and interesting real-world experience while helping improve the health of the Chicago River. Source | Ozinga RMC Inc. Generational improvements continue Generation 1 FHSUs (below) featured an integral concrete "foot" designed to keep the end farthest from the stream bank of the bottom of the riverbed so it didn't fll up with sediment. Rebar was allowed to protrude through these feet to anchor them into the riverbank, preventing units from moving once installed. Those heavy units, however, proved difcult to move and handle. A second-generation design, built this spring, used lighter aggregate, eliminated the concrete foot, and paired 2 FHSUs with wooden risers banded to wooden pallets (at left). Signifcantly lighter, the new design also had its issues and likely will be modifed. Source | Ozinga RMC Inc.