عنوان
پدید آورنده
موضوع
رده
کتابخانه
محل استقرار
TL52492
انگلیسی
Characterizing Physical Properties of Lightweight Aggregate Made from Waste Coal Ash Using X-Ray Computed Tomography
[Thesis]
Balapour, Mohammad
Farnam, Yaghoob A
Drexel University
2020
84 p.
M.S.
Drexel University
2020
X-ray computed tomography (XCT) is a powerful nondestructive technique that can provide valuable information about the physical properties of materials. This thesis uses XCT to evaluate the physical properties of a new type of lightweight aggregate (LWA) from low- and high-calcium waste coal combustion ashes (CCAs), i.e., spherical porous reactive lightweight aggregate (SPoRA). Raw data acquisition audition and image processing methodology are introduced in this study to evaluate the physical properties of SPoRA. The pore-solid structure of SPoRA is qualitatively analyzed using the 2D reconstructed XCT images. The physical properties of the LWAs including total porosity, closed porosity, pore volume and sphericity are characterized. Analysis of 2D images indicates that the SPoRA possesses a core-shell structure, where large pores are accumulated in the shell while core embeds small interconnected pores. Moreover, it is observed that increasing the fluxing agent (i.e., NaOH) concentration for preparation of SPoRA leads to a reduction of the core size and an increase in the shell thickness. It is found that the total porosity measured for SPoRA ranges from 39.6% to 57.8% by volume indicating that SPoRA is light enough to be considered as LWA and theoretically possesses a great capacity for storing water in their pore structure. The closed porosity of SPoRA also ranges from 0.54% to 5.3% by total volume of sample, which implies that a great portion of pores are connected to the outer surface in SPoRA; therefore, water can easily penetrate through interconnected pores for a promising water absorption/desorption behavior in SPoRA. The sphericity of LWAs (which is an influential factor on the workability for concrete) is also found to range from 1 (meaning perfect sphere) to 0.75. It can be concluded that SPoRA appears to be a promising LWA to be used in applications such lightweight concrete construction, lightweight geotechnical applications, internal curing of concrete and/or green roof applications. Future research can be devoted to (i) characterizing the quantity and properties of liquid phase formed in SPoRA, (ii) identifying the gaseous phases/products formed during sintering that lead to lightening mechanism, (iii) studying the mechanical properties of SPoRA in micro/meso scale and finally, (iv) assessing SPoRA's performance in concrete to further validate SPoRA's suitability for application in construction and geotechnical industry.
Civil engineering
Materials science
Balapour, Mohammad
Farnam, Yaghoob A
Drexel University
مطالعه متن کتاب p
[Thesis]
276903
a
Y
