Effect of Specimen Shapes on Compressive Strength of Engineered Cementitious Composites (ECCs) with Different Values of Water-to-Binder Ratio and PVA Fiber

This paper presents experimental investigation on the effect of specimen shapes of engineered cementitious composites (ECCs). In various types of cement concrete, cubic specimens have shown to have higher compressive strength than cylindrical specimens. However, no research has been conducted yet to study the effect of specimen shapes (cube or cylinder) on the compressive strength of new cementitious materials like ECC. In this study, cylinders and cubic specimens were prepared to study the effect on the compressive strength and elastic modulus of the ECCs. In addition, the effects of water-to-binder ratio (w / b) and polyvinyl alcohol (PVA) fiber on the compressive strength and the modulus of elasticity of ECC were investigated. Two categories of ECC were considered, with PVA fibers (PVA-ECC or shortly PE) and without PVA fibers (NO-PVA-ECC or simply NE). Three different w / b ratios were used for each material category. The results revealed that PVA fiber has a significant effect on ductility of ECCs but with minor effect on compressive strength for both the specimen shapes. As expected, the cubic specimens of ECC exhibit higher strengths than the cylindrical counterparts after 28 days. Based on the measurement data, new generalized correlation models were proposed via linear regression analysis showing the relation between the cylindrical and cubic shapes for ECC at 14 and 28 days of age. Another interesting models are proposed to establish the correlations between the compressive strength as well as the moduli of elasticity of ECCs with and without PVA fiber, for both specimen shapes.