This document specifies the reference methods used for type testing and in case of dispute, for the determination of particle density and water absorption of normal weight and lightweight aggregates. Other methods can be used for other purposes, such as factory production control, provided that an appropriate working relationship with the reference method has been established. For convenience, some of these other methods are also described in this document. The reference methods for normal weight aggregates are: - a wire basket method for aggregate particles retained on the 31,5 mm sieve (Clause 7, except for railway ballast which uses Annex B); - a pyknometer method for aggregate particles passing the 31,5 mm sieve and retained on the 4 mm sieve (Clause 8); - a pyknometer method for aggregate particles passing the 4 mm sieve and retained on the 0,063 mm sieve (Clause 9). In Clauses 7, 8 and 9, three different particle densities (oven-dried particle density, saturated and surface-dried particle density and apparent particle density) and water absorption are determined after a soaking period of 24 h. In Annex B, the oven-dried particle density is determined after soaking in water to constant mass. For aggregate particles passing the 31,5 mm sieve and retained on the 4 mm sieve, the wire basket method in Clause 7 can be used as an alternative to the pyknometer method in Clause 8. NOTE 1 The wire basket method can also be used for single aggregate particles retained on the 63 mm sieve. NOTE 2 The pyknometer method described in Clause 8 can be used as an alternative for aggregates passing the 4 mm sieve and retained on the 2 mm sieve. The reference methods for lightweight aggregates are: - a pyknometer method for aggregate particles passing the 31,5 mm sieve and retained on the 4 mm sieve (Annex C). Three different particle densities (oven-dried; saturated and surface-dried; apparent) and water absorption are determined after pre-drying and a soaking period of 24 h; - a method, using a Büchner funnel, for aggregate particles passing the 4 mm sieve (Annex D). The three particle densities and water absorption are determined using a vacuum in the range of 50 mbar to 100 mbar for at least five minutes. Three other methods for normal weight aggregates can be used to determine the pre-dried particle density, as specified in normative Annexes A and H: - a wire basket method for aggregate particles passing the 63 mm sieve and retained on the 31,5 mm sieve (A.3); - a pyknometer method for aggregate particles passing the 31,5 mm sieve and retained on the 0,063 mm sieve (A.4); - a pyknometer method for aggregate particles passing the 31,5 mm sieve, including the 0/0,063 mm size fraction (Annex H). NOTE 3 If water absorption is less than about 1,5 %, the apparent particle density can be assessed using the pre-dried particle density method as defined in Annex A. The quick method in normative Annex E can be used in factory production control to determine the apparent particle density of lightweight aggregates. The method in informative Annex F can be used to determine the particle density and water absorption of aggregate particles passing the 4 mm sieve. Data on the density of water at various temperatures is specified in normative Annex G. Guidance on the significance and use of the various density and water absorption parameters is given in informative Annex I. Precision data are presented in informative Annex J.