Preparation and properties of foundry dust/Portland cement based composites and superhydrophobic coatings

In this study, Found dust (FD) and Portland cement (PC) based bulk composites and superhydrophobic coatings were prepared to utilize the solid waste FD and improve the water permeability. First, the compositions, structures, pore parameters, and mechanical properties of the FD/PC composites were tested and analyzed, indicating that the mechanical strength of the FD/PC composites decreased with increasing FD content. The flexural compressive strength and compressive strength of the FD/PC composites with an FD content of 10% reduced by only 8.5% and 9.8%, respectively, compared to that of the neat hardened cement paste (HCP). At greater than 10% FD content, the mechanical strength of the FD/PC composite material drastically reduced. Second, the FD and PC based superhydrophobic coatings were prepared using a simple brush-coating method by introducing polydimethylsiloxane as a hydrophobic admixture. The composite coating exhibits superhydrophobicity after stored at room temperature for 24 h. In addition, the mechanical robustness of the FD and PC composite based coating is excellent in the abrasion and peeling test and was further improved by double-layer coating method. Particularly, the superhydrophobic coating can be easily repaired after getting damaged. Furthermore, the water absorption of the superhydrophobic coating modified FD/PC composites reduced by more than 76% in comparison with that of the uncoated FD/PC composites. (C) 2020 Elsevier Ltd. All rights reserved.