Strength Development Characteristics of SBR-Modified Cementitious Mixtures for 3-Demensional Concrete Printing

The properties of normal cementitious mixtures currently employed to the construction projects cannot be used to the three-dimensional concrete printing technology. This study experimentally investigated the compressive and flexural strength development of styrene-butadiene rubber (SBR)-modified cementitious mixtures for use as basic three-dimensional concrete printing (3DCP) materials. The SBR/cement ratio was a variable of the mix proportion used to produce cast and printed specimens. Experiments were conducted using these specimens to determine the compressive and flexural strength levels of the SBR-modified cementitious mixtures. The results indicated that the compressive strengths of the SBR-modified cementitious mixtures proposed in this study were never less than those of existing 3D concrete printing materials previously introduced for 3DCP applications. It was confirmed that the addition of SBR latex effectively improved the strength of the cementitious mixtures because the relative compressive and flexural strengths increased with increases in the SBR/cement ratio. Moreover, the higher early (i.e., 1-day) strength indicates that the SBR-modified cementitious mixtures would be advantageous to the 3DCP process. However, the compressive and flexural strengths of the printed specimens were weaker than those of the cast specimens.