INFLUENCE OF COARSE AGGREGATE SIZE AND CEMENT MATRIX STRENGTH ON STRESS–CRACK WIDTH RELATIONSHIP OF CONCRETE

Abstract

In this paper, the effect of coarse aggregate size (single grade of 5-10 mm and 16-20 mm) and matrix strength (concrete compressive strength of 40 and 80 MPa respectively) on stress-crack width ( σ-w ) relationship is studied. The investigation is based on three point bending tests implemented by fictitious crack analyses. The result shows that coarse aggregate size and cement matrix strength significantly influence the shape of σ -w curve. For the same total aggregate content, in the case of compressive strength is equal to 40 MPa, small size aggregate leads to a high tensile strength and a sharp stress dropping after the peak stress. As concrete compressive strength increases to 80 MPa, the effect of aggregate size on σ -w relationship almost vanishes. Coarse aggregate size and matrix strength are both important parameters which influence the crack bridging law of concrete. In addition, a four-linear function is accurate enough to reflect the characteristics of the stress-crack width relationship of concrete.