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Performance and mechanism on a high durable silica alumina based cementitious material composed of coal refuse and coal combustion byproducts

Author

Yuan Yao, University of the Pacific

Date of Award

2012

Document Type

Dissertation - Pacific Access Restricted

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Pharmaceutical and Chemical Sciences

First Advisor

Henghu Sun

First Committee Member

Ravi Jain

Second Committee Member

William Stringfellow

Third Committee Member

Jianhua Ren

Fourth Committee Member

Qingliang Zhao

Abstract

Coal refuse and combustion byproducts as industrial solid waste stockpiles have become great threats to the environment. Recycling is one practical solution to utilize this huge amount of solid waste through activation as substitute for ordinary Portland cement. The central goal of this dissertation is to investigate and develop a new silica-alumina based cementitious material largely using coal refuse as a constituent that will be ideal for durable construction, mine backfill, mine sealing and waste disposal stabilization applications. This new material is an environment-friendly alternative to ordinary Portland cement. The main constituents of the new material are coal refuse and other coal wastes including coal sludge and coal combustion products (CCPs). Compared with conventional cement production, successful development of this new technology could potentially save energy and reduce greenhouse gas emissions, recycle vast amount of coal wastes, and significantly reduce production cost. A systematic research has been conducted to seek for an optimal solution for enhancing pozzolanic reactivity of the relatively inert solid waste-coal refuse in order to improve the utilization efficiency and economy benefit for construction and building materials. The results show that thermal activation temperature ranging from 20°C to 950°C significantly increases the workability and pozzolanic property of the coal refuse. The optimal activation condition is between 700°C to 800°C within a period of 30 to 60 minutes. Microanalysis illustrates that the improved pozzolanic reactivity contributes to the generated amorphous materials from parts of inert aluminosilicate minerals by destroying the crystallize structure during the thermal activation. In the coal refuse, kaolinite begins to transfer into metakaol in at 550°C, the chlorite minerals disappear at 750°C, and muscovite 2M 1 gradually dehydroxylates to muscovite HT. Furthermore, this research examines the environmental acceptance and economic feasibility of this technology and found that this silica alumina-based cementitious material not only meets EPA requirements but also shows several advantages in industrial application.

Pages

184

ISBN

9781267734273

Recommended Citation

Yao, Yuan. (2012). Performance and mechanism on a high durable silica alumina based cementitious material composed of coal refuse and coal combustion byproducts. University of the Pacific, Dissertation - Pacific Access Restricted. https://scholarlycommons.pacific.edu/uop_etds/155

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