Development of Component Composition of Engineered Cementitious Composites

The use of engineering cementitious composites – a specially developed cement-based material reinforced with fibers – allows to enhance the bearing capacity, stability under static and dynamic influences, as well as durability of building structures. The effect of component composition of engineering cementitious composites on workability, flexural and compressive strength was investigated from micromechanics principles point of view. It is shown that the optimal cement to sand ratio, partial replacement cement by fly ash, incorporation of polycarboxylate superplasticizer, as well as reinforcement of the engineered composites structure with dispersed fibers contribute to their mechanical properties both at early and later hardening period. The modified engineered cementitious composites are characterized 28-days compressive strength 61 MPa, flexural strength – 14.5 MPa and crack resistance coefficient 0.24. Partial replacement of Portland cement by fly ash causes formation of needle and fibrous hydration products in unclinker part that reinforce the matrix on the micro- and nanolevel and the phenomena of “self-reinforcement” is realized.