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Title: Strain Capacity of Strain‐Hardening UHP‐FRC Part II: Synthetic Fibers

Author(s): Shah

Publication: Web Session



Appears on pages(s):



Date: 10/17/2021

Achieving a cement matrix with the highest compressive strength has been a challenge to engineers and scientists since the birth of concrete. While strength exceeding 500 MPa have been reported in the past with very small size specimens, in its present form, UHPC is first to achieve, using conventional processing, strengths in the range of 150 to 250 MPa on a structural scale. It is generally observed in cement-based composites, that the higher the compressive strength the higher the tensile strength which primarily remains in the range of 1/12 to 1/15 f’c. While post-cracking tensile strengths exceeding 35 MPa have been reported in UHP-FRC with steel fibers, the majority of test results reported fall below 15 MPa with a corresponding strain on average below 4/1000; such a relatively small strain capacity represents a severe constraint to wide scale structural applications of the composite. Part I of this study focused on the strain capacity of UHP-FRC with steel fibers. In this Part II, FRC composites with synthetic fibers are evaluated with particular attention to the use of high molecular weight polyethylene (HDPE or HMWPE) fibers and PVA fibers. In theory, everything else being equal, the use of synthetic fibers should lead to higher strain capacities simply because their elastic modulus is smaller than that of steel, and controls crack opening in the multiple cracking phases. However, other important factors driving strain capacity are uncovered and the findings are correlated with those obtained from Part I with steel fibers.