Volume expansion characteristics of single component moisture cured polyurethane mixture
In order to study the volume expansion characteristics of single component moisture cured polyure-thane mixture,the volume expansion characterization method was proposed based on a vernier caliper.In ad-dition,the macro and micro morphologies after volume expansion were analyzed.The law of volume expan-sion under different factors and the effect of volume expansion on void ratio were studied.Finally,a method of inhibiting volume expansion was proposed.The results show that due to the small void ratio of the polyure-thane mixture,it is difficult for the carbon dioxide gas generated by the solidification reaction to escape com-pletely,and there will be a large number of macro and micro pore structures inside the mixture.A Marshall sample can produce up to 1.5 mm expansion deformation.Increasing the compaction temperature,using sec-ondary compaction or adding calcium hydroxide can significantly reduce the volume expansion of the mixture,and also improve the pavement performance.When the ratio of polyurethane to stone increases,the volume expansion of the mixture increases monotonously,and the void ratio decreases first and then increases.In or-der to control the volume expansion,it is recommended that the compaction temperature is 45 to 65 ℃,and the ratio of polyurethane to stone should not be too large.When calcium hydroxide is added,its mass fraction should not exceed 1％.
polyurethane mixturevolume expansioncompaction temperaturesecondary compactionratio of polyurethane to stonecalcium hydroxide
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