地聚合物固化淤泥强度增长影响因素及机制分析

Influencing factors and mechanism analysis of strength development of geopolymer stabilized sludge

针对传统固化剂碳排放及高能耗等问题,提出以煤系偏高岭土(CMK)地聚合物为固化剂稳固淤泥,首先通过无侧限抗压强度试验确定碱激发剂的配合比,并在此基础上研究碱固比、前驱物掺量、NaOH浓度、养护龄期、养护温度和矿渣掺量等因素对固化淤泥力学特性的影响,最后通过扫描电镜试验和X射线衍射试验分析固化淤泥的微观结构。试验结果表明:地聚合物固化淤泥强度随Na2SiO3:NaOH增加而先升后降,合理的碱激发剂的配合比为Na2SiO3:NaOH=75:25;固化淤泥强度随碱固比、前驱物掺量和NaOH浓度提高而增强,而延长养护龄期、提高养护温度和掺入矿渣对固化淤泥强度提升更显著;微观结果表明,地聚合物固化淤泥中没有新矿物生成,随着碱固比、前驱物掺量、NaOH浓度、养护龄期、养护温度和矿渣掺量提高,无定形凝胶产物N-A-S-H和C-(A)-S-H增多,凝胶通过黏结作用增强了土颗粒间凝聚力,并能有效填充土颗粒间隙,使土体结构更密实,是固化淤泥强度提升的主要原因。

To solve the problem of carbon emission and high energy consumption of traditional binder,the coal-bearing metakaolin(CMK)geopolymer was used to stabilize sludge.The unconfined compressive strength(UCS)test was conducted to determine the proportion of alkali activator firstly.On this basis,the effects of alkali-precursor ratio,precursor content,NaOH molarity,curing time,curing temperature and slag content on the mechanical properties of stabilized sludge were investigated.Finally,the SEM and XRD tests were conducted to analyse the microstructure of stabilized sludge.The results showed that the UCS of stabilized sludge first increased and then decreased with increasing Na2 SiO3:NaOH ratio and the rational proportion of alkali activator of geopolymer was Na2SiO3:NaOH=75:25.The UCS increased as the alkali-precursor ratio,precursor content and NaOH molarity increased.As the curing time,curing temperature and slag content increased,the UCS of stabilized sludge improved more obviously.The microstructural analysis showed that no new minerals were formed in geopolymer stabilized sludge.With the increase of alkali-precursor ratio,precursor content,NaOH molarity,curing time,curing temperature and slag content,the amount of amorphous N-A-S-H and C-(A)-S-H gels increased,which made the soil structure denser through bonding and filling effects,thus increasing the strength of stabilized sludge.