Basic Performance Test of Durable Protective Coatings for Concrete Beams
To study the protective effect of coatings on the durability of bridge concrete beams,three types of film-forming coatings,namely modified polyurethane coatings(e.g.,PS1 and PS3)and modified epoxy resin coatings(e.g.,E3),were selected through indoor geotechnical tests.A series of basic performance tests of protective coatings for concrete durability were conducted on these coatings.The adhesion,crack tracking,acid and alkali resistance,salt spray resistance and weather resistance of the coating were tested and analyzed.The results showed that the adhesion of E3 and PS3 coatings were 4.71 MPa and 3.62 MPa respectively,which met the adhesion requirements of synthetic film coatings.The bonding strength between E3 coating and concrete substrate was higher than that of PS3 coating;PS3 exhibited a phenomenon of adhesive film formation during the tensioning process,and some of the coatings adhered to the interior of the cracks,thus facilitat-ed itself to follow the crack propagation and achieving a certain effect of sealing the cracks;PS1,PS3 and E3 exhibited good alkali resistance and salt spray resistance;PS1 and E3 had better acid resistance than PS3.There were no bubbles on the surface of PS1 and E3 before and after the experiment,while a small amount of bubbles with a diameter of less than 0.5mm appeared on the surface of PS3;After aging test for 1,000 hours,the coating of PS1 and PS3 were basically sta-ble while E3 had the worst weather resistance,specifically after 500 hours of aging test,it had completely lost light with a loss rate up to 82%.The above three coatings had a certain protective effect on concrete,which could improve the durability of concrete and extend the service life of concrete structures.
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