Surface-Colour Characteristics and Flow of Carbon Aminosilica Black Paste Using a Redispersible Polymer.

The surface colour of exposed concrete is one of the most obvious characteristics of quality because it is the first one to be seen. However, efflorescence generally changes the colour impression of the material surface and of the concrete facade as a whole. This study investigated the efflorescence of carbon aminosilica black (CASB) mortar and the effect of redispersible polymer powder (RPP) on the physical properties of CASB mortar. For this purpose, a flow test and colour evaluation was carried out on white Portland cement paste and mortar mixed with CASB by changing the proportion of RPP. RPP modifies the mechanical properties of the mortar by forming a polymer film in the cementitious matrix. The film prevents the transport of soluble calcium towards the surface and decreases efflorescence. As a result, the colour appearance of CASB mortar improved with increasing RPP content.