Effects of Substrate Texture and Moisture Conditions on Ultra-High Performance Concrete and Silica Fume Concrete Overlay Bond Strengths

Abstract Direct tension tests were conducted to investigate the effects of substrate moisture conditions and texture on ultra-high performance concrete (UHPC) overlay bond strengths. Improper surface preparation can result in inadequate strengths and, severe cases, lack bond. To demonstrate importance preparation, pull-off performed overlaid slabs that had two extreme (saturated dried) prior application. Saturated a tined, tined-light sand blasted, or tined-medium blasted texture. Dried either tined an exposed aggregate specimens with textures achieved average 0.924, 1.45, 1.95 MPa, respectively. surfaced zero strength. Surface ranged from saturated dry also investigated by allowing surfaces for 15, 30, 45, 60 minutes application UHPC overlay. Tined-light dried 2.86, 2.01, 1.59, 0.165 Results showed proper saturating adequate strengths, properly saturated, produced excellent drastic consequences not maintaining delaying up drastically reduce