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iDEA: DREXEL LIBRARIES E-REPOSITORY AND ARCHIVES

iDEA: DREXEL LIBRARIES E-REPOSITORY AND ARCHIVES

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Evaluation of the Potential Use of Spherical Porous Reactive Aggregate (SPoRA) for Internal Curing of Cementitious System

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Title
Evaluation of the Potential Use of Spherical Porous Reactive Aggregate (SPoRA) for Internal Curing of Cementitious System
Author(s)
Zhao, Weijin
Advisor(s)
Farnam, Yaghoob
Keywords
Civil engineering; Cement composites; Concrete--Curing; Aggregates (Building materials); Specific gravity; Absorption; Materials science; Environmental engineering
Date
2017-12
Publisher
Drexel University
Thesis
M.S., Civil engineering -- Drexel University, 2017
Abstract
Curing has been considered as an essential process for cementitious materials. Proper curing enables the cement to hydrate developing its potential strength and improving its durability. Inadequate curing can lead to the plastic shrinkage cracking and stress due to drying or temperature changes. Using external water or placing a curing compound on the surface of the concrete to reduce water loss due to evaporation are traditional ways of curing concrete. These methods may not cure the entire concrete and may require longer curing time. Methods have been proposed to help increase curing efficiency such as providing internal curing in concrete. Internal curing is often referred to as curing concrete from the inside by using pre-wetted porous lightweight aggregate (LWA) to provide additional curing water throughout the concrete mixture. This thesis focuses on a novel lightweight aggregate, Spherical Porous Reactive Aggregate (SPoRA), which is produced from waste coal combustion bottom ash and its potential use for internal curing in cementitious system. The production of SPoRA is first introduced in this study, which is converting bottom ash to porous lightweight aggregate using sintering process. Physical properties of SPoRA such as specific gravity and vacuum absorption were determined and analyzed. The LWA used for internal curing should supply a sufficient volume of water to counteract the effect of self-desiccation. Therefore, the water absorption property test was conducted to determine if SPoRA could absorb sufficient water. Once mixing the SPoRA with cement, the desorption property of releasing water for internal curing is also significant as SPoRA should be able to release water over time to properly cure concrete internally. The loss of water from SPoRA can be described through a desorption isotherm that was determined using sorption analyzer in this study. Finally, the physical properties, absorption and desorption behavior of SPoRA are compared to two traditional types of lightweight aggregate (i.e., Expanded Shale, Clay, and Slate) and one foamed glass (produced from waste glass) available in the market.
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