Microwave-Accelerated Curing of Cement-Based Materials: Compressive Strength and Maturity Modeling

Abstract:

Microwave energy is applied to cure cement-based materials with microwave power and time of application. First, the dielectric permittivity of them during a 24-hour first-hydration period at a frequency of 2.45 ± 0.05 GHz is measured and analyzed. Second, the characteristics of hardened cement paste as subjected to microwave energy with multi-mode rectangular wave guide, with specific attention to temperature rise, microstructure and development. This article presents a theoretical analysis to relate the compressive strengths of the CBM when subjected to microwave energy at an operating frequency of 2.45 GHz with a multi-mode cavity. The effects of water-to-solid mass ratios, aggregates, pozzolan materials, microwave power levels, application times, sequential processes, delay times, and comparisons with conventional curing (lime saturated-deionized water) were taken into account. The results indicated that for increasing the compressive strength, the main coefficient (a) as the Richards model are up to the highest value, the optimal energy level (microwave power × application time) should be in the range of 2.0 to 3.0 KJ when the specimen size was of  70.0 mm  40.0 mm in order to avoid the position of highest electric field strength within the cavity. Furthermore, the calculated compressive strengths based on the maturity concept overestimated the strength during 28 day first hydration time of the microwave-cured cement-based materials using the formula:

• Periodical: Key Engineering Materials (Volume 484)
• Pages: 210-221
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.484.210
• Online since: July 2011
• Authors: Natt Makul, Dinesh Kumar Agrawal
• Keywords: Accelerated Curing, Cement-Based Material, Maturity Modeling, Micro-Wave

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