We recently reported on how today’s concrete industry could take a few lessons from ancient Roman engineers when it comes to more environmentally friendly compositions and manufacturing methods. Now from southern Italy comes news of an international research effort aimed at incorporating recycled and natural fibers and aggregates into modern concrete formulations to develop a more sustainable product.
“Concrete is one of the most commonly used construction materials in the world,” Enzo Martinelli, a civil engineer at the University of Salerno, Italy, said in this video. “In Europe alone, we produce the equivalent of one cubic meter of concrete per inhabitant each year.”
Called EnCoRe (Environmentally-friendly solutions for Concrete with Recycled and natural components), the three-phase project involves mixing concrete formulations with various types and amounts of recycled aggregates, recycled industrial fibers, and natural fibers. The scientists then use both mechanical testing and computer simulation to evaluate the resulting materials’ fresh and hardened behavior. Mechanical test procedures shown in the video include compression and bending tests.
Recycled aggregates pose difficulties for concrete composition and properties due to their variable surface textures and absorption capacities, according to the EnCoRe website. Investigators are evaluating concretes made with a range of recycled aggregate types and sizes, including demolition rubble, glass, and brick either as fine aggregate or to replace some Portland cement in the mixture.
According to investigator Antonio Caggiano, a civil engineer from the University of Buenos Aires (Argentina), use of recycled fibers poses a different challenge. “We’ve realized that the main problem with industrial recycled fibers is their geometry,” Caggiano said in the video. “As they have already been used for other applications, their geometry isn’t regular or smooth. So they don’t mix in so well with cement.” Recycled fiber materials being evaluated include PVC, PET and other polymers, as well as steel and rubber particles from tires, according to the project website.
Phase 3 of the research will take the same approach—mixing of various concrete compositions, followed by physical and computer-based evaluation of the materials’ fresh and hardened properties—to investigate the effects of addition of natural fibers on concrete strength and durability. Possible natural fiber materials to be investigated in the EnCoRe research are not specified, but previous work (pdf) with natural reinforcements at Georgia Tech (Atlanta) investigated the effects of wood cellulose, sisal, bamboo, jute, and elephant grass fibers, among other materials.
This phase of the research program appears to be aimed primarily at providing shelter in developing countries. “The need for a safe and secure shelter is an inherent global problem,” the EnCoRe project website says. “Numerous challenges remain in order to produce environmentally friendly construction products which are structurally safe and durable for a long term.”
If cement and concrete are your field, it is not too late to register for the ACerS Cements Division’s annual technical meeting—4th Advances in Cement-based Materials: Characterization, Processing, Modeling and Sensing—July 8–10 at the University of Illinois at Urbana-Champaign. Symposia topics include cement chemistry and nano/microstructure; alternative cementitious materials; rheology and advances in SCC; smart materials and sensors; advances in material characterization techniques; durability and lifecycle modeling; and advances in computational material science and chemo/mechanical modeling of cement based materials. UIUC professor Leslie Struble will deliver the Della Roy Lecture titled “Calcium in Geopolymers.” Meeting organizers also have planned a tutorial session on the structure of hydration products, opening reception, poster session, and networking dinner for students.