聚酯纤维对生活垃圾焚烧飞灰/沥青混合料TSR的改善效果

Improvement Effect of Polyester Fiber on TSR of MSWI Fly Ash/Asphalt Mixture

为了缓解焚烧飞灰对沥青混合料冻融劈裂强度的影响,利用聚酯纤维桥连加筋、增韧阻裂的效应,将其作为添加剂添加到焚烧飞灰/沥青混合料中。试验对比分析了单掺聚酯纤维、聚酯纤维与水泥造粒共作用两种方法对焚烧飞灰/沥青混合料冻融劈裂强度的改善效果,并研究了不同纤维种类、沥青种类的叠加效应。结果表明:焚烧飞灰因含可溶盐(如氯盐、硫酸盐等)、遇水反应膨胀物(如CaO,Ca(OH)_(2)等)、低价阳离子(如Na^(+),K^(+)等)等物质,分别能够在低温下产生结晶膨胀作用、水化时固相体积增加以及与沥青膜接触产生乳化与侵蚀作用等,严重损害了沥青混合料的TSR;单掺聚酯纤维时,对焚烧飞灰/沥青混合料的冻融劈裂强度提高程度有限且难以弥补焚烧飞灰对TSR造成的影响,单独采用水泥封装焚烧飞灰时,对可溶盐溢出引起的TSR性能恶化的缓解效果亦有限,而在两者的共作用下TSR改善效果显著且满足规范要求;对于质量比分别为1:0.25,1:0.5,1:1,1:1.5的焚烧飞灰/水泥颗粒,在聚酯纤维的叠加作用下,TSR满足规范要求的焚烧飞灰最大容许掺量依次为0.71%,1.82%,2.24%,3.36%;在对焚烧飞灰/沥青混合料的TSR改善效果上,聚酯纤维因桥连加筋效果显著而优于木质素纤维,改性沥青因物理力学性能优势而优于普通沥青。

In order to alleviate the influence of municipal solid waste incineration(MSWI)fly ash on the freeze-thaw splitting strength of asphalt mixture,polyester fiber is used as additive in MSWI fly ash/asphalt mixture depends on the effect of its bridging reinforcement,toughening and cracking resistance.The improvement effects of freeze-thaw split strength of MSWI fly ash/asphalt mixture are compared and analyzed by methods of single-blending polyester fiber and the combined action of polyester fiber and cement granulating,and the superposition effects of different fiber and asphalt types are studied.The result shows that(1)MSWI fly ash contains soluble salts(such as chloride and sulfate,etc.),swelling products that react with water(such as CaO,Ca(OH)_(2),etc.),and low-valent cations(such as Na^(+),K^(+),etc.),which can cause crystal expansion at low temperature,increase in solid volume during hydration,and emulsification and erosion caused by contact with asphalt membrane,which seriously damage the TSR of asphalt mixture.(2)Adding polyester fiber alone can not greatly improve the freeze-thaw split strength of MSWI fly ash/asphalt mixture,and it is difficult to make up for the influence of incineration of fly ash on TSR,the performance degradation of TSR caused by the overflow of soluble salt can not be alleviated only by using cement to encapsulate MSWI fly ash.However,under the combined action of both,the TSR improvement effect is significant and meets the specification requirements.(3)For the MSWI fly ash/cement particles with mass ratio of 1:0.25,1:0.5,1:1,1:1.5 respectively,under the superimposed effect of polyester fiber,the maximum allowable dosage of MSWI fly ash that make TSR meet the requirements of the specification is 0.71%,1.82%,2.24%,and 3.36% in order.(4)In terms of improving the TSR of the MSWI fly ash/asphalt mixture,polyester fiber is superior to lignin fiber due to its significant bridging reinforcement effect,and modified asphalt is superior to ordinary asphalt due to its advantages in physical and mechanical properties.