Properties of concrete subjected to explosively generated impact and impulse loading.

The use of models to simulate full scale structural effects has
long been attempted and various types of models have been developed.
One type, the replica model, in which prototype materials are used was
selected for this study. Much interest has been shown in the past
on damage prediction based on extrapolation of the results from small
explosive charge tests. In this study, scale model concrete ground
slabs have been subjected to high rates of loading using explosively
propelled copper and aluminium projectiles impacting on the concrete
to air surface and explosive devices buried in the soil beneath the
concrete slab. The copper or aluminium projectile was produced from
a truncated cone of metal in direct contact with a shaped charge of
RDX/TNT explosive. The subsurface charge was uncased PE4 plastic
explosive inserted into a hole through the slab and into the soil.
In many tests the hole was produced by the metal jet impact without
any modification. Other scaled concrete targets have also been tested
using explosively propelled projectiles. Transient results from the
tests have been collected using high speed photography, electrical
resistance strain gauges, crack velocity detection devices and a
projectile velocity measurement system. Other measurements of post
test damage have utilised stereoscopic photography, coloured particles
of soil in the foundations of the concrete slabs and a scanning
electron microscope. Concretes of various strengths and densities
have been used but all conformed to a scaled down specification for
pavement quality concrete. Explosive charges were similarly scaled
in size from prototype devices. Some additional experimental work
has been carried out to obtain fundamental data on the explosive
charges and on 'perspex', metal and concrete blocks for calculation
and comparison purposes. Comparisons are also made with work of a
related nature undertaken at larger scales.