The U. S. method (here called Rigden-Anderson) described in Anderson (1987) stipulates 25 strokes of the 100 g dead weight. Results of the measurements form the basis for calculating the volume of air voids in a dry compacted filler. Only 1.0-1.3 g of filler is needed to conduct the testing. After determining the content of air voids in the compacted filler, the calculation of free and fixed binder may be performed (by mass and by volume). The concept of free and fixed binder is presented in Chapter 3.
Rigden’s method (the European procedure) and Ridgen’s as modified by Anderson (the U. S. procedure) produce different contents of air voids in the same compacted [54] filler. This is caused by a lower compacting effort in the U. S. method (25 strokes) than in the European one (100 strokes). Much research, particularly in the United States, has been carried out with the use of Ridgen-Anderson’s method. The results would be very valuable for Europeans, but test conditions differ to such an extent that a simple comparison of results is rather impossible.
