疏浚土免烧法制备组骨料及其性能研究

以太湖疏浚土为原料，采用免烧法工艺制备小粒径（＜12 mm）免烧裹壳骨料（WSLAs）。在WSLAs的基础上，通过黏结、裹壳工艺制备免烧粗骨料（UCLAs）。以 20~25 mm UCLAs为研究对象，探究了WSLAs级配对UCLAs密度、粒径分布、颗粒强度的影响。依据GB/T 14685-2011 对UCLAs的堆积密度、吸水率、筒压强度、压碎值、抗冻性、耐盐性等性能进行测试，并与天然粗骨料（NCAs）做性能对比。结果表明，WSLAs的最优级配为：1~3 mm 10%、3~5 mm 25%、5~8 mm 50%、8~12 mm 15%。在该WSLAs级配下制备高性能UCLAs的密度、颗粒强度分别为 1.644 g/cm3、2.75 MPa。同时，UCLAs内部结构稳定、壳层结构密实，使得其吸水率仅为 1.89%，从而表现出与NCAs相当的耐久性能，二者经 25 次抗冻融循环、25 d盐溶液侵蚀均无质量损失。UCLAs的压碎值为 18.6%，与NCAs的压碎值 9.5%相比较高，但符合GB/T 14685-2011 对Ⅱ类粗骨料的要求，可应用于建筑混凝土中起骨架支撑作用。 Taihu lake dredged sediment was selected as raw material to produce smallsize (＜12 mm) wrapshell lightweight aggregates (WSLAs) from unburned process.The unburned coarse and lightweight aggregates (UCLAs) was obtained by bonding and shell wrapping process from WSLAs.The effects of WSLAs gradation on UCLAs density,particle size distribution and particle strength were then investigated with 20~25 mm UCLAs in this study.The characteristics,such as size distribution,packing density,water adsorption,cylinder compressive strength,crushing value and freezingthawing resistance of UCLAs,were examined and compared with natural coarse aggregates (NCAs) in accordance with the Chinese National Standards (GB/T 14685-2011).The results showed that the best performance UCLAs were WSLAs1~3 mm accounting for 10%,3~5 mm for 25%,5~8 mm for 50%,and 8~12 mm for 15%.The density and particle strength of this best performance UCLAs obtained from this WSLAs combination were 1.644 g/cm3 and 2.75 MPa,respectively.At the same time, the internal structure of UCLAs was stable and the shell structure was dense.The water absorption rate was only 189%,which showed a durability being comparable to that of NCAs.There was not mass loss in 25 days of salt solution erosion and 25 cycles of freezethaw resistance.The crushing value of UCLAs was 18.6%,which was higher than that of NCAs (9.5%),but meets the requirement of GB/T 14685-2011 for class Ⅱ coarse aggregate.Therefore, it can be used as skeleton support in building concrete. 中交天航环保工程有限公司基金支持（1700030003；1700030031）