Detecting Fire Damaged Concrete Using Laser Scanning

Concrete is the single most widely used building material throughout the UK and the world. A major advantage of properly designed concrete construction is its inherent resistance to the effects of unwanted fires. The detection and location of structural deficiencies in buildings is of vital importance from a health and safety point of view. In some cases the damage to these materials is easy to detect and identify. Materials such as wood and metal deform such that the deformation, such as twisting, bending, obvious changing in colour and obvious changes in size can usually be seen by eye and thus decisions on parts of a structure that need to be replaced when looking at these materials can be relatively easily made. Concrete on the other hand changes very little in shape and size when damaged, which makes it more difficult to detect when damage has occurred. One of the causes of structural deficiencies in buildings is fire.
In 2004 the cost of building fires in the UK was estimated to be in excess of £2 million a day. Consequently there has never been a greater need for structures to be assessed for fire damage to ensure safety and also to plan and carry out appropriate and cost effective repairs. Terrestrial laser scanners measure the 3D coordinates of any object automatically in a systematic manner in near real time. In addition to 3D coordinates laser scanners are able to measure the intensity value of the returned laser signal. Tests have been carried out to evaluate whether the intensity return values obtained via laser scanning can be used as a means of detecting the temperature to which concrete has been heated. The results of these tests will be presented.