腐殖酸对污泥固化土长期强度的劣化效应

研究腐殖酸对污泥固化土长期强度的影响具有重要意义。对有机质含量较低的污泥分别添加0.5%,1.5%,3%,4.5%,6%的腐殖酸,基于水泥、偏高岭土、石灰等固化剂进行固化,得到标准养护状态下240 d污泥固化土的抗弯强度、应力-应变关系及破坏应变的发展规律。研究结果表明:在外加腐殖酸和污泥固有有机质缓释腐殖酸的协同作用下,固化土初期抗弯强度急剧增加,随后有不同程度的降低;腐殖酸添加量从0.5%到6%,各龄期固化土抗弯强度几乎都有一定程度劣化,固化作用和腐殖酸侵蚀作用平衡点由180 d提前到60 d;高含量腐殖酸固化土的破坏模式呈“塑性→脆性→偏塑性”变化规律,腐殖酸含量越大,塑性破坏作用越明显。

Degradation Effect of Humic Acid on Long-term Strength of Solidified Sludge Soil

Studies on the effect of humic acid on the long-term strength of solidified sludge soil,are of great importance.In this research,sludge with low organic matter content was solidified by mixtures of cement,metakaolin,and lime,etc.On this basis,humic acid in proportion of 0.5％,1.5％,3％ and 4.5％,6％,respectively,was added into the sludge.The development laws of bending strength,stress-strain relationship and failure strain of solidified sludge soil under standard curing condition for 240 days were obtained.Results revealed that 1) under the joint actions of humic acid and inherent humic acid slowly released from organic matters of the sludge,the initial bending strength of solidified soil increased rapidly and then decreased to different extents;2) when humic acid content increased from 0.5％ to 6％,the bending strength of solidified soil at different ages almost degraded to a certain degree,and the balance between solidification and humic acid erosion occurred in advance,from the 180th day to the 60th day;3) the failure mode of solidified soil with high content of humic acid experienced the tendency from plastic failure to brittle failure,and then to partial plastic failure,and the bigger content of humic acid is,the more obvious the action of plastic failure is.