Article ID Journal Published Year Pages File Type
653794 International Communications in Heat and Mass Transfer 2010 10 Pages PDF
Abstract

The characteristics of cementitious materials subjected to microwave energy are presented. First, the dielectric properties of cementitious materials during a 24-hour first-hydration period were measured at a frequency of 2.45 GHz. Second, the characteristics of hardened cement paste as subjected to heating for a short period (without loss of moisture) by microwave energy with a single-mode rectangular wave guide, with specific attention to temperature rise, compressive strength, and the use of the maturity function was investigated experimentally and theoretically. The obtained results show that dielectric properties are relatively high and remain constant during the dormant period. After this period, the hydration reaction resumes and dielectric properties decrease rapidly. With the use of microwave heating, early-age strength increases during the first 14 days; however, during the next 14 days, early-age strength decreases slightly, until it reaches its lowest at the 28-day mark. The temperature rise as actually recorded at the center of the sample during microwave heating in our experiment consistently agreed with figures calculated by a mathematical model.

Related Topics
Physical Sciences and Engineering Chemical Engineering Fluid Flow and Transfer Processes
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