What is BS EN 13286‑4 about?
BS EN 13286‑4 is the fourth part of the multi-series of documents that is applicable to unbound and hydraulically bound mixtures.
BS EN 13286‑4 specifies a method for the determination of the relationship between the dry density and water content of a mixture using vibrating hammer compaction.
BS EN 13286‑4 applies to mixtures that contain no more than 10 % by mass of the mixture retained on the 40 mm test sieve.
Who is BS EN 13286‑4 for?
BS EN 13286‑4 on unbound and hydraulically bound mixtures is applicable to: 
- Manufacturers and suppliers of unbound and hydraulically bound mixtures
- Suppliers of binders such as cement, fly-ash needed to make hydraulically bound mixtures
- Equipment suppliers
- Civil engineers
- Contractors
- Highway and road transport authorities
Why should you use BS EN 13286‑4?  
A hydraulically bound mixture is a mixture of aggregate, water and hydraulic binder and is one of the most commonly used materials in pavement sub-base layers where cement-treated bases or cement-bound materials have traditionally been used. For the optimum functioning of hydraulically bound mixtures, water content is a important factor as it decides on the hardness of the material that gains strength over time by creating interlocking bonds.
Through the testing methods described under BS EN 13286‑4, users will be able to determine the relationship between the dry density and water content of a mixture using vibrating hammer compaction. Also determine the procedure for calculating and plotting the curves corresponding to 0 %, 5 % and 10 % air voids.
This will help you in ensuring that loads are sampled at regular intervals for compliance determination of the maximum dry unit weight and water content range for successful compaction of granular soils using a vibrating hammer. This allows for higher maximum soil density at lower optimum moisture content.
These provisions given in BS EN 13286-1 will help you to ensure quality and performance by reducing the cost of material production by eliminating quarrying, crushing, and screening operations. For repaving projects, it reduces handling and transportation costs too. With all methods of compaction, the effect of increasing the compactive energy is to increase the maximum dry density and to decrease the optimum moisture content.
What’s changed since the last update?
BS EN 13286‑4:2021 supersedes BS EN 13286‑4:2003, which is withdrawn. BS EN 13286‑4:2021 has been editorially revised along with the following changes:
- Removal of the particle size requirement at 20mm which was considered unnecessary and contrary to current usage
- Advice on the use of the test method with absorbent aggregates, soils and hydraulically bound mixtures
- Inclusion of text relating to the possible types of compaction curves and definition/selection of the resulting optimum water content
- Removal of the Annex: Compactibility test for graded aggregates, which was deemed unnecessary.
