compatibility of ultra high performance concrete as repair material

115113Relative Dynamic Modulus (%)1111091071051031019997950 50 100 150 200 250 300NSC 300 FT (1)NSC 300 FT (2)NSC 300 FT (3)NSC 300 FT (4)Freeze-thaw cyclesFigure 4.6 Relative Dynamic Modulus of NSC samples subjected to 300 freeze-thaw cycles4.1.2 Indirect tensile loadingSeveral cylinders were cast from each NSC and UHPC mixes in order to assess thequality of both materials. Table 4.2 gives the compressive strength of the repair and oldlayers on the same day as the splitting test was carried, in order to have a measure of thequality of both materials. By using Equation 4.1, given by ACI318-11, the splittingtensile strength for the concrete substrate was as well estimated.f ct = 6.7 ∗ f c in psiEquation 4.1where f ct is the splitting tensile strength and f c is the compressive strength.It should be mentioned that both f c and f ct do not represent the influence that the freezethawcycles could have on the overlay and substrate strengths of the composite specimensdue to the fact that these values are calculated from cylinders that were not exposed tofreeze-thaw cycling conditions.74