Experimental study on demulsification speed of emulsified asphalt based on equivalent surface area principle

In order to simplify the demulsification speed test of emulsified asphalt, rapid-breaking, medium-breaking and slow-breaking emulsified asphalt as well as different aggregates were selected for the demulsification speed test. The specific surface area of each single grade was determined by the actual measurement, and the equivalent aggregate was collected according to the principle of equivalent surface area. The results show that the equivalent aggregate can be composed by the assembling of gradations smaller than 0.075mm and one or two bigger gradations. Therefore, the types of gradation in the equivalent aggregate will be reduced by one-half compared with that in the standard aggregate. The surface area of the equivalent aggregate is the same as that of the standard aggregate, and under a certain volume ratio, the demulsification rate determined by equivalent aggregate or standard aggregate is the same.There is also a critical volume ratio existing for the equivalent aggregate, If the critical volume ratio is exceeded, the demulsification rate determined by the equivalent aggregate will be greatly different from that determined by the standard aggregate. It is also found that the volume ratio turns to 1 without any changes when the proportion of gradation smaller than 0.075mm reaches 25%-30%.