Experimental study on the on-site long-term service performance of polyurethane insulation layer in water reservoir dams
In order to further explore the degradation characteristics of polyurethane insulation layer after long-term on-situ service of reservoir dams,taking the Xianghongdian Reservoir Dam as an example,field tests were conducted on the bonding performance between different layers of the insulation layer in typical sites of downstream face of dam.Scanning electron mi-croscopy was used to conduct microscopic morphology characterization analysis on polyurethane samples taken from the site.Key performance indicators such as thermal conductivity and compressive strength were tested,and the corresponding surface heat release coefficient of the concrete insulation layer was calculated and analyzed.The results showed that the tensile bond-ing strength between the polyurethane layer and the concrete substrate,as well as the compressive performance of on-site sam-pled polyurethane had decreased.And the declined degree of wet polyurethane was much greater than dry polyurethane.Com-pared with the initial addition of polyurethane,the thermal conductivity of the polyurethane insulation layer in the dry area had increased by 22.9%due to the aging effect of the microporous structure,however the insulation service state still exactly meets the original design requirements.For insulation layers in areas with moisture content,their insulation service status no longer meets the requirements.During the long-term service of the insulation layer,the coupling effect of aging of polyurethane micro-porous structure and external water intrusion will significantly intensify the degradation process of polyurethane,significantly re-ducing its adhesion,compression performance,and insulation performance.
dam heating insulationpolyurethanethermal conductivityin-service state
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