Improvement of the surface quality and aesthetics of ultra-high-performance concrete

Abstract

The low moisture content of ultra-high-performance concrete (UHPC) combined with its minimal bleeding leads to quick drying of its exposed surfaces by way of moisture evaporation and self-desiccation. The result is the formation of a rough texture and occasional cracks on the exposed surfaces of UHPC within hours after its placement and finishing. This phenomenon is referred to as ‘elephant skin’ formation. Different strategies were devised and experimentally evaluated for the control of elephant skin formation on exposed UHPC surfaces. These strategies emphasised reduction of the moisture loss from the surface, enhancement of early-age dimensional stability and increase in plastic shrinkage crack resistance. The potential for elephant skin formation was assessed through monitoring of the surface aesthetics, crack area, penetration resistance and temperature under exposure to air flow and radiation. The results indicated that measures that effectively reduce moisture loss from the surface are most effective in controlling elephant skin formation on the exposed surfaces of UHPC.