This is one in a series of Traffic Advisory Leaflets providing guidance on methods of working and innovative techniques aimed at reducing traffic congestion due to road works. The series is aimed at utility companies, highway authorities, contractors, equipment suppliers and others involved in road (or street) works. Each leaflet in this series is based on research carried out by TRL Limited on behalf of the Department for Transport and Transport for London. This Traffic Advisory Leaflet covers the use of hydraulically bound mixtures (HBMs) in the sub-base and base layers of reinstatements. HBMs can be used as an alternative to granular sub-base material in accordance with the options given in the Specification for the Reinstatement of Openings in Highways (SROH). One of the environmental advantages of using HBMs is that fewer lorry trips to and from the site are likely to be required. This, combined with the potentially quicker compaction times sometimes associated with HBMs, can help reduce congestion for road users. A hydraulically bound mixture is a mixture of aggregate, water and hydraulic binder. Possible binders include cement, fly-ash, ground and/or granulated slag (see Figure 1), lime, pozzolan and combinations thereof. Binders can be generic or proprietary. HBM 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. (Author/publisher)
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