Experimental program

Three mixture proportions of the mortars were prepared with different FA replacement ratios of 0%,35%and 55%by mass of binder.Prisms with a cross section of 40 mm×40 mm and a length of 160 mm were tested under a four-point bending test as shown in Figure 1.Predamage was defined as the ratio of preloading to the ultimate strength of the specimen,i.e.30%,60%and 80%.The specimens were first applied by different levels of preloading,and then stored in lime-saturated water at(23±2)℃for 30 days.Afterwards,one batch of the specimens were loaded till failure while the other were again preloaded and immersed to examine the impact of repeated loading.

Figure 1　Four-point bending test(unit:mm)