Fiber - bridging constitutive law of engineered cementitious composites

This paper reports on the development of high-performance fiber-reinforced cementitious composites (HPFRCC), taking into account environmental sustainability considerations. Engineered cementitious composites (ECC), a unique member of HPFRCC featuring high tensile ductility with ultra-high volumes of fly ash (HVFA) replacement (up to 85% by weight) of cement, are proposed in this paper. While micromechanics is applied in many aspects of the material design process, the emphasis of this study is placed on the effect of fly ash content on altering material microstructure and mechanical properties. Experimental results show that HVFA ECCs while incorporating high volumes of recycled fly ash, can retain a long-term tensile ductility of approximately 2 to 3%. Significantly, both the crack width and free drying shrinkage are reduced with an increase of the fly ash amount, which may benefit the long-term durability of HVFA ECC structures. Micromechanics analysis indicates that the increase of fiber/matrix interface frictional bond in HVFA ECCs is responsible for the tight crack width. In addition, HVFA ECCs show a robustness improvement by achieving more saturated multiple cracking while reducing environmental impact through the use of industrial waste stream material instead of cement