碱激发粉煤灰和矿粉改性疏浚淤泥力学特性及显微结构研究

Study of microstructure and mechanical properties of dredged silt solidified using fly ash and slag stimulated by alkali

采用水玻璃作为碱激发剂激发粉煤灰和矿粉的活性来固化疏浚淤泥,对固化淤泥进行无侧限抗压强度试验、扫描电镜(SEM)以及X射线衍射(XRD)测试,研究了固化材料配比、龄期、水玻璃掺量及水玻璃模数对固化疏浚淤泥强度的影响,确定了各组分之间的最佳配比,观测了固化淤泥的物相组成及显微结构特征.力学试验结果表明:水玻璃掺量7%、模数1.0~1.5时对粉煤灰和矿粉的激发效果最优,相比于粉煤灰,水玻璃对矿粉的激发效果更佳;水玻璃模数相同的情况下,矿粉掺量越大强度越高;各组分最优配比(疏浚淤泥、矿粉、水玻璃质量比为60∶40∶7)时,28d无侧限抗压强度可达到12 140kPa.SEM和XRD试验结果显示:在水玻璃的激发下,固化淤泥水化生成长石类和沸石类等晶相,这些晶相连接紧密,形成致密的微观结构,这是固化后疏浚淤泥强度的最重要来源.

Water glass is used as alkali activator to activate the activity of fly ash and slag to solidify dredged silt,and unconfined compressive strength tests,scanning electron microscopy(SEM)and X ray diffraction(XRD)tests are carried out to investigate the effect of material ratio,curing age,water glass content and modulus on the solidified dredged silt strength.Furthermore,the optimum ratio between components is determined,and the phase composition and microstructure characteristics of the solidified silt are observed.The mechanical experiment results indicate that the stimulatory effect of water glass on fly ash and slag is the best when water glass content is 7% and the modulus is between 1.0 and 1.5.The hydration activity of slag is better than that of fly ash in the alkali conditions.Furthermore,the unconfined compressive strength of the solidified dredged silt increases with the increasing of slag content under the same water glass modulus.Under the optimum ratio that the mass ratio of dredged silt,slag and water glass is 60∶40∶7,the 28 dunconfined compressive strength is up to 12 140 kPa.The results of SEM and XRD show that the hydration products feldspar and zeolite-like phases form dense microstructures,which are the most important sources of the solidified dredged silt strength.