Volume 14, Issue 2, April 2017, Pages 369–378

• Nicu Toader^a, , , , 
• Werner Sobek^a, 
• Klaus G Nickel^b

• ^a Institute for Lightweight Structures and Conceptual Design (ILEK), Stuttgart Universität, 70569 Stuttgart, Germany
• ^b Institute for Geoscience (IFG), Applied Mineralogy, Eberhard-Karls-Universität Tübingen, 72074 Tübingen, Germany

• Abstract

  Functionally Graded Concrete (FGC) is fabricated at the Institute for Lightweight Structures and Conceptual Design (ILEK) by using a layer-by-layer technique with two different technological procedures: casting and dry spraying. Functional gradations are developed from two reference mixtures with diametrically opposed characteristics in terms of density, porosity, compression strength and elasticity modulus. In this study the first mixture consists of Normal Density Concrete (NDC), with density about 2160 kg·m⁻³ while the second mixture helps to obtain a very lightweight concrete, with density about 830 kg·m⁻³. The FGC specimens have layers with different alternating porosities and provide superior deformability capacity under bulk compression compared to NDC specimens. In addition, the FGC specimens experienced a graceful failure behaviour, absorbing high amounts of energy during extended compression paths. The porosity variation inside the layout of tested specimens is inspired by the internal structure of sea urchin spines ofheterocentrotus mammillatus, a promising role model for energy absorption in biomimetic engineering.

  Keywords

  • biomimetic engineering; 
  • energy absorption; 
  • sea urchin spine; 
  • functionally graded concrete; 
  • graceful failure behaviour
  • Full text is available at 
  • http://www.sciencedirect.com/science/article/pii/
  • S1672652917300173