The main thrust of the study is to examine the suitability of the various materials used in coastal defence schemes and in river defences. Typically, these include breakwaters, seawalls, groynes, beach re-charge schemes, river bank protection and flood-proofing materials/barriers. In each case it is important to select materials that are physically strong enough for the job;

economically viable; and environmentally and socially sustainable.

Over the past 10 years, HR Wallingford has been building up expertise in the area of materials (including reclaimed/recycled ones) for flood and coastal defence engineering projects.

This has recently been recognised by DEFRA and the Environment Agency (EA), who will be supporting HR Wallingford in the long-term as a Centre of Expertise in Materials.

As part of this work HR Wallingford will be collaborating with a wide range of key experts from other organisations.

The latest phase of work has commenced with the award of a contract to HR Wallingford to prepare an overview/reference paper on materials commonly used in river and coastal engineering.

Staff from HR Wallingford will consider five types of material:

Conventional inert materials such as rock, stone, steel, sand, gravel, concrete, geotextiles and plastic; Natural materials/ systems like timber, willow and grass; Reclaimed/recycled materials including demolition waste, redundant tyres, steel slag and china clay waste;

specialist materials; coatings and sealants.

HR Wallingford says it has been tasked with facilitating the take-up by industry of new knowledge; and producing summaries of best practice.

For this reason, in parallel with the overview work, DEFRA and the EA are also supporting HR Wallingford in projects on specific materials where the need for guidance has already been identified. These include:

Rock armour: large blocks of rock are often used in structures designed to protect coastlines against wave attack and erosion.

Partners from Britain and France are carrying out research, funded by the UK Environment Agency, and the French government agencies dealing with coastal and civil works into methods of understanding, testing and measuring rock integrity.

Timber: sustainable use of timber is a highly topical subject, particularly where the timber is hardwood sourced from tropical rain forests. Timber for coastal and river structures, however, has to be sufficiently durable to withstand the aggressive environment and in many cases only hardwoods are suitable.

Waste materials: waste materials are difficult and costly to dispose of. The research overview will hopefully spotlight some areas where 'waste' can become 'resource'.

One example that has already been identified is that of used vehicle tyres.

One way in which waste tyres could become a resource is by using them in coastal and river engineering. HR Wallingford has just been successful in securing a project to examine the potential for this.