FREEZE-THAW DURABILITY OF MICROWAVE CURED AIR-ENTRAINED CONCRETE

The strength development of concrete can be greatly accelerated by cur ing with microwave energy. Microwave curing can therefore be beneficia l to construction operations such as concrete precasting and repair. T o provide freeze-thaw durability for infrastructure applications, air entrainment has to be introduced. In this investigation, the freeze-th aw resistance of microwave cured air-entrained concrete is measured, a nd compared to that of air-entrained concrete under normal curing. The ir compressive strength at 14 days and air-void characteristics are al so measured and compared. The test results indicate that microwave cur ing can impair the freeze-thaw durability of high w/c concrete but not for low w/c concrete. Also, under microwave curing, the decrease in s trength due to air entrainment becomes more significant. Based on thes e observations, it is recommended that for microwave cured air-entrain ed concrete, a low w/c ratio should be employed. (C) 1997 Elsevier Sci ence Ltd.