BS 13286-1:2021 pdf download – Unbound and hydraulically bound mixtures Part 1: Test methods for laboratory reference density and water content – Introduction, general requirements and sampling
This document specifies a number of test methods for the determination of the relationship between the water content and the density of unbound and hydraulically bound mixtures under specified test conditions.
The test results provide an estimate of the mixture density that can be achieved and provides a reference parameter for assessing the density of the compacted layer of the mixture. The test results are used as a basis for specifying requirements for hydraulically bound and unbound mixtures. The test result also allows a conclusion to be drawn as to the water content at which a mixture can be satisfactorily compacted in order to achieve a given density.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
EN 932-1:1996, Tests for general properties of aggregates – Part 1: Methods for sampling EN 932-2:1999, Tests for general properties of aggregates – Part 2: Methods for reducing laboratory samples
EN 932-5, Tests for general properties of aggregates – Part 5: Common equipment and calibration 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 932-1:1996, EN 932-2:1999 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at
— ISO Online browsing platform: available at
3.1 laboratory dry density maximum dry density that can be determined from the dry density/water content relationship derived using a specified test method
3.2 optimum water content water content associated with the maximum value of laboratory dry density 3.3 aggregate size designation of aggregate in terms of lower (d) and upper (D) sieve sizes expressed as d/D Note 1 to entry: This designation accepts the presence of some particles which will be retained on the upper sieve (oversize) and some which will pass the lower sieve (undersize). The lower sieve size (d) may be zero.
4 Principle 4.1 Relationship between dry density and water content
The solid particles of unbound and hydraulically bound mixtures are compacted, i.e. packed more closely together, thereby increasing the dry density of the mixture. The dry density which can be achieved depends on the effective compaction work applied and on the amount of water present in the mixture. For a given degree of compaction work applied to a particular mixture, an optimum water content exists at which the dry density obtained reaches a maximum value. These principles are illustrated in Figure 1.
NOTE 1 The mixtures which are not free draining will, in most cases, establish a well-defined optimum water content and maximum density. However, for free draining mixtures, the laboratory tests will not, in many cases, produce a well-defined water density relationship. The maximum density obtained will generally be less than that obtained in the finished pavement layer.
NOTE 2 For free draining mixtures it is possible to draw two curves: one for the relationship between the dry density and the initial water content (before compaction) and another for the relationship between the dry density and the final water content (after compaction). The possible difference between these curves shows the draining capacity of the mixture.
4.2 Choice of test method
The following four test methods are used for compaction:
— EN 13286-2: Proctor compaction;
— EN 13286-3: Vibrocompression with controlled parameters;
— EN 13286-4: Vibrating hammer;
— EN 13286-5: Vibrating table.
Each method applies different levels of compactive effort, and is suitable for different aggregate sizes.BS 13286-1 pdf download.