Morphological Characterization of γ-Al_2O_3 Membranes Fabricated from Ammonium Aluminum Sulphate

Supported γ-Al2O3 membranes without defects were prepared by the sol-gel procedure. The sol-gel method involved peptization of a boehmite (AlOOH) sol prepared from ammonium aluminium sulphate. The morphology of the supported membranes was characterized by scanning electron microscopy (SEM) and 3D rotational microscopy. Furthermore, the effects of different preparing conditions on morphological characteristics of the membrane were also investigated. The results show that PVA is a good crack-preventing agent and the morphology of supported membranes is affected by many factors, such as Al2O3 and PVA contents of the sol, drying and sintering procedures and intrinsic defects on the substrate surface.

Mechanical Properties of Lime-Fly Ash-Sulphate Aluminum Cement Stabilized Loess

Lime-fly ash stabilized loess has a poor early strength,which results in a later traffic opening time when it is used as road-base materials.Consideration of the significant early strength characteristics of sulphate aluminum cement(SAC),it is always added into the lime-fly ash mixtures to improve the early strength of stabilized loess.However,there is a scarcity of research on the mechanical behavior of lime-fly ash-SAC stabilized loess and there is a lack of quantitative evaluation of loess stabilized with binder materials.This research explored the effects of the amount of binder materials,curing time and porosity on the unconfined compressive strength(UCS),splitting tensile strength(STS),cohesion(c)and friction angle(φ)of lime-fly ash-SAC stabilized loess by a series of unconfined compressive tests(UCT)and splitting tensile tests(STT).The results indicate that an increase in curing time and a decrease in porosity lead to a continuous increase in the UCS and STS for lime-fly ash-SAC stabilized loess.The addition of SAC has a prominent enhancement in the early strength of lime-fly ash-SAC stabilized loess.When the curing time,porosity,and binder content were constant,the UCS and STS increase with increasing SAC content;For a stabilized loess with 30%binder content and 5%SAC content after 1 day of curing,the UCS was greater than 0.7 MPa,which meets the requirement of opening traffic,so lime-fly ash-SAC stabilized loess could be used as an excellent maintenance material for road-base;In accordance with the analysis of testing data,empirical relationships between the UCS and STS of lime-fly-SAC stabilized loess and key effect factors(binder materials content,curing time and porosity)were developed,which can provide references for reasonably selecting the amount of binder materials,compaction degree and curing period to meet the required strength of practical engineering.Finally,based on the Mohr-Coulomb theory and the above empirical relationships,a simpler method for calculating the c andφof stabilized loess was proposed,with which,the shear strength parameters can be determined only by UCT or STT.