Effect of high strain-rates on the tensile constitutive response of Ecofriendly Ductile Cementitious Composite (EDCC)

Eco-Friendly Ductile Cementitious Composites (EDCCs) are a newly developed class of engineered cementitious composites that contains reduced amounts of cement and very high volumes of fly ash (or other SCMs) and show very high ductility and elastoplastic response in pure tension. These characteristics make EDCCs a promising material for seismic retrofit applications. This paper describes an experimental program where the effects of higher rates of loading on the tensile behaviour of EDCC are assessed. Strain-rate ratios of the orders of 103 (static to dynamic) are investigated. The rate of loading is chosen to coincide with strain-rates normally observed during earthquakes. The EDCCs tested are fiber reinforced concrete materials having a total fiber volume of 2%. Non-oiled Poly-Vinyl Alcohol (PVA) fibers and Poly-Ethylene Terephthalate (PET) fibres are used in the EDCC mixes in three different combinations: 2% PVA, 2% PET, a hybrid mix of 1% PVA + 1% PET fibers. For the quasi-static tests, a normal closed-loop test set-up is used. For the dynamic tests, a newly designed test setup using an air gun is utilized. This investigation discloses that the approximate static to dynamic ratio for the tensile strength of EDCC varies between 0.75 and 1.00 in magnitude; and, the strain capacity varies between 1.0 and 3.0 for this material. Results demonstrated that EDCCs are highly strain-rate sensitive materials and their performance during an earthquake should not be assessed from routine quasi-static tests.