垃圾焚烧飞灰水泥固化体强度稳定性研究

针对垃圾焚烧飞灰安全处置技术要求，采用水泥对其进行固化、稳定化处理，研究了不同水泥添加量、不同养护时间和渗沥液浸泡时间对固化体无侧限抗压强度及破坏特性的影响，并对垃圾渗沥液的侵蚀机制进行了分析。结果表明：当水泥添加量小于5%，养护时间小于3 d时，飞灰固化体在渗沥液浸泡下迅速解体，垃圾渗沥液的侵蚀对飞灰固化体的强度有较大的影响，浸泡后的固化体呈现出明显的应变软化特征，而未经浸泡的固化体的强度增长符合y=a1-exp(-bt)]模式。随着水泥添加量及养护时间的增加，飞灰固化体无侧限抗压强度增加，破坏应变减小，而随着浸泡时间的增加，飞灰固化体的无侧限抗压强度先增大后减小，转折点大约在5～7 d，破坏应变近似呈线性增大。渗沥液对飞灰固化体的侵蚀主要是其成分抑制了固化体水化反应和破坏了水化产物。研究成果可为垃圾焚烧飞灰的安全处置技术提供理论依据和参数支持。

Study of strength stability of municipal solid waste incinerator fly ash solidified by cement

According to the technical requirements of safe disposal of municipal solid waste incinerator (MSWI) fly ash, the fly ash is solidified by cement. The unconfined compression strength and destruction characteristics of fly ash solidified blocks with different cement contents, curing times and soaking times are studied. Then the erosion mechanism of leachate is analyzed. The test results show that the fly ash solidified blocks are destructed quickly after soaking in leachate with cement content less than 5% and curing time less than 3 days. The erosion of leachate has a great influence on the strength of fly ash solidified blocks. The fly ash solidified blocks present an obvious strain softening characteristic after soaking. The strength of fly ash solidified blocks without soaking in leachate accords with the mode of y=a1-exp(-bt)]. With the increase of cement content and curing time, the unconfined compression strength increases and the failure strain decreases. But with the increase of soaking time, the strength increases firstly and then decreases; the turning point is about on 5-7 days; and the failure strain increases linearly. The erosion mechanism is that leachate can inhibit hydration reaction and destroy hydration products of fly ash solidified blocks. The results can provide theoretical basis and data support for the safe disposal of MSWI fly ash.