Abstract
Auxetic behavior refers to material with negative Poisson's ratio. In this research, a new type of cementitious auxetic material is developed. A novel crack bridging auxetic mechanism is discovered which is in contrast with a local buckling mechanism commonly employed to trigger auxetic behavior. Taking advantage of 3D printing techniques, cementitious cellular composite (CCC) specimens with auxetic cellular structures were produced. Meanwhile, cementitious materials with different fiber content were used as constituent material. Uniaxial compression and cyclic loading tests were performed on the CCCs. Experiments show that with proper constituent material, CCCs can exhibit auxetic behavior which is induced by crack bridging process of the cementitious constituent material. In addition, strain hardening behavior can be identified in the stress-strain curve under uniaxial compression and consequently high specific energy absorption is obtained. Furthermore, 2.5% of reversible deformation which is significantly higher than conventional cementitious materials under cyclic loading is obtained within 25,000 cycles. Obvious fatigue damage is observed in the first 3000 cycles, afterwards signs of mechanical properties recovering can be found. The discovered auxetic mechanism indicates a new designing direction for brittle materials to achieve auxetic behaviors.
Highlights
Cementitious materials are the most widely used construction ma terials in the world due to their excellent properties and relatively low cost
A similar structure was used before [37,60,61] in which local buckling is the mechanism of the auxetic behavior, for cellular structures made of cementitious materials the mechanism has not been studied yet and it is probably rather different
Since cementitious materials are much weaker in tension than in compression, cracks will initiate at the tension side of the joint (Fig. 3c)
Summary
Cementitious materials are the most widely used construction ma terials in the world due to their excellent properties and relatively low cost. Studies have shown that mechanical properties of cementitious materials depend on their constituent phases (e.g. properties of matrix [1,2,3], aggregates [4,5] and fibers [6,7]) and the geometrical characteristics and spatial distribution of these constituents [8,9] This is referred to as “micro-structure” or “meso-structure” of cementitious materials. Examples include Kagome structures with high relative frac ture toughness [30,31], octet lattices with high relative strength [32,33] and auxetic structures with high impact resistance [34,35,36,37] Among those geometries, auxetic structures are of particular interest for cementitious materials because of their excellent mechanical properties which might be applied in many engineering practices
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
