MATRIX DESIGN FOR PSEUDO-STRAIN-HARDENING FIBER-REINFORCED CEMENTITIOUS COMPOSITES

Pseudo-strain-hardening behaviour under direct tensile loading in shor t fibre reinforced cement composites designed with quantitative guidan ce from micromechanics hers been demonstrated experimentally, and cond itions for the ductile behaviour of such engineered cementitious compo sites (ECC) have been formulated theoretically. In this paper special focus is placed on the influence of matrix properties on composite pse udo-strain-hardening. An experimental program is undertaken to study t he dependence of the matrix properties on its mix compositions governe d by water/cement and the sand/cement ratios. The theoretical and expe rimental knowledge thus obtained are combined to propose an innovative procedure for the design of composites using different types of matri x. The study is motivated by the need to develop a new class of ECCs w ith improved elastic modulus by the addition of fine aggregates to the cementitious matrix. Finally, a new composite is designed, and shown experimentally to exhibit the desirable features of pseudo-strain-hard ening behaviour and improved elastic modulus.