Polydopamine/palygorskite hybrid-reinforced epoxy coatings adhered to a concrete surface

Purpose The purpose of this study is to prepare a polydopamine (PDA)–palygorskite (Pal) hybrid-reinforced epoxy coating with high adhesion strength on wet concrete surface. Design/methodology/approach One synthetic step was adopted to prepare novel PDA–Pal hybrid epoxy coating. The process and product were analyzed and confirmed by FIRT, thermogravimetric analysis and scanning electron microscopy. The mass fraction of PDA–Pal hybrid affecting the adhesion strength of epoxy coating was analyzed and confirmed by pull-off test. Findings PDA–Pal hybrid mass fractions of 0, 1, 3 and 5 were added to the coatings. For a 5 Wt.% PDA–Pal hybrid content, the adhesive strengths on the saturated or underwater concrete surfaces increased to 4.0 and 2.5 MPa, respectively. In addition, the tensile mechanical property of the epoxy coating improved significantly after PDA–Pal addition. Practical implications This new epoxy coating hybrid by PDA–Pal could be applied as a concrete protective layer near water or in wet or damp environments. Originality/value Introduction of PDA–Pal hybrid to prepare epoxy coating with high adhesion strength on wet concrete surface has not been systematically studied previously.