Surface treatment of concrete by retarder: Investigation of pattern change and preliminary application

As a novel surface treatment technology, graphic concrete features its meticulous pattern and an excellent visual expression. In this paper, the effect of concentration of retarder, curing age, water-cement ratio (w/c) and sand-cement ratio (s/c) on area change percentage (ACP) of the transferred patterns was investigated. The results show that with the increase of concentration of retarder, the ACP increased sharply from negative to positive, while the ACP decreased from positive to negative with a rise of curing age of concrete. It presents strength gradient in the concrete for the synergistic effect of retarder diffusion and strength development of concrete matrix which lead to the various pattern change of graphic concrete. The practical graphic concrete with size of 270 mm × 330 mm was prepared with 20% retarder, 0.3 w/c, 2.0 s/c and cured at 20 ± 1 °C for 20 h, which shown an extremely high similarity between transferred patterns and designed patterns.