Enhancing the Printing Quality and Mechanical Properties of 3D-Printed Cement Composites with Date Syrup-Based Graphene Coated Sand Hybrid

This study addresses the influence of adding date syrup-based graphene-coated sand hybrid (D-GSH) as a partial substitute for sand in 3D-printed cement composites, exploring its potential to enhance both fresh and hardened properties. Incorporating 0.5% D-GSH significantly improved the printing quality compared to the control mix, as evidenced by the reduction in the variance in thickness of double layers from 38% to 28%. In addition, buildability was enhanced by 116% with an open time of 27 min. The rheological properties showed reduced viscosity and shear stress against shear rates, thereby enhancing flowability. Moreover, the addition of 0.5% D-GSH increased the compressive strength, flexural strength, and elastic modulus by 62%, 118%, and 40%, respectively, after 28 days of curing, compared with a mix containing silica fume. Microstructural analysis revealed that D-GSH effectively fills gaps, bridges cracks, and bonds with the hydration products of cement matrix, thus improving the mechanical properties.