คุณสมบัติทางกายภาพของวัสดุซีเมนต์ที่แข็งตัวแล้วภายใต้การบ่มด้วยพลังงานไมโครเวฟร่วมกับ ระบบสายพานลำเลียงต่อเนื่อง

Abstract

At present, a cement-based materials curing technique by means of the principle of volumetric heat generating within processed material by using microwave energy has admired and instead of the conventional method in which heat transfers from outside surface inward on account of high performance and potential. This paper presents the results in experimentally of physical properties of cement paste, mortar, and concrete under microwave energy cooperating with continuous belt thermal processor. Its internal structure consists of 8 magnetrons, at which generate microwave at operating frequency in the range of       2.45 ± 0.05 Gigahertz (GHz) and power per 1 magnetron equal to 800 watts). The effective variables studied were power of microwave, application time, water-to-cement ratios (W/C), sand-to-cement ratios (S/C) and the influence of air content and chemical admixture in kind of set-retarded agent in concrete upon temperature rise, moisture content and compressive strength and comparison the strength among microwave-, water-, and air-cured concrete. From the test results, it was found that an increasing of microwave power owning to increase the rate of temperature rise, maximum temperature and the decreasing rate of moisture content of cement paste, mortar and concrete. As well as, the effect occurred on temperature when water-to-cement ratios of cement paste decreased, whereas the mortars containing with and without set-retarded agent and air content did not affected directly on the rate of temperature rise and moisture content within internal structure. Besides, the later age compressive strength of concrete decreased when the power of microwave increased and increment of compressive strength affected by adding the retarder agent.