Bomb-proof concrete

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Engineers at Liverpool University have tested an Ultra High Performance Fibre Reinforced Concrete (UHPFRC) designed to reduce the impact of bomb blasts in public places.

Working alongside the Centre for the Protection of National Infrastructure, researchers have found that the new concrete is able to absorb a thousand times more energy than conventional mixtures.

While the concrete has yet to be introduced in the UK, it has been utilised in Australia in the design of slender footbridges and to strengthen government buildings against potential mortar attacks. Other applications include bomb-proof litter bins and protection barriers.

The university has explored the limits of the concrete’s capability through a range of tests for dynamic bending and indirect stress conducted at RAF Spadeadam in Cumbria.

Trials revealed that the concrete resisted high explosion blasts without producing shrapnel from the back of its panels. According to Liverpool University, this factor will prove significant in its ability to be used in protection barriers that shield people from explosions.

Prof Steve Millard said: ‘Many of London’s tourist landmarks are surrounded by concrete to protect against terrorist attacks. However, the material does not absorb sufficient energy to prevent the creation of shrapnel, which is one of the most lethal consequences of a bomb blast. UHPFRC is different because needle-thin steel fibres are added into the concrete mix instead of steel reinforcing bars to increase its tensile strength.

‘We carried out a number of high explosion tests; gradually reducing the distance to the explosive charge to examine the concrete’s bending strength and capacity to absorb energy. Our results showed the new UHPFRC material had an enhanced tension and compression strength of 500 per cent greater than conventional concrete. This makes UHPFRC a suitable material for use in anti-terrorism applications.’

The research was undertaken as part of the Engineering and Physical Sciences Research Council’s (EPSRC’s) Think Crime-4 initiative, which involved collaboration with Sheffield University.