World-first forensic tool for fire-damaged concrete structure

When concrete is exposed to intense fire, materials in the concrete can decompose, leading to a deterioration of strength. Yet there is no widely accepted method of evaluating this damage, making the choice between repair and demolition difficult.

Now, a team of researchers, led by Dr Youngsun Heo of the Korean Institute of Civil Engineering and Building Technology (KICT), have developed the Fire Forensic Investigation of Structure (F2IS) tool that can answer the question.

“After fire exposure, service life of concrete structure can drop within two weeks, depending on the damage level,” says Heo.

“The higher the volume of pores in concrete arising from fire, the faster is the dramatic reduction of life expectancy. If the structure is not going to be rebuilt, immediate diagnosis and subsequent repairing work should be proceeded even when there is minor damage.”

Setting up a specimen, conducting a fire test for damaging the specimen and sampling from the fire-damaged concrete specimen are simply described in this video file. Credit: Korea Institute of Civil Engineering and Building Technology (KICT)

By taking tiny 1-2g samples for every 10mm of depth of fire-damaged concrete, F2IS can predict the impacts of the fire – such as temperature, length of time spent in the heat and how heat diffused through the structure – with 80% accuracy.

Using this data and deep learning, the tool assesses which key features to address. The whole process takes less than two weeks to support continuation of housing and businesses.

2 psd work dia results 1
(a) With a portable hand drilling device, samples of only 1~2 g are being taken at every 10 mm depth, up to 40 mm so that the least damage to the concrete specimen is achieved. (b) Final outputs of fire-damaged temperatures at each depth where samples are taken and time-temperature curves at surface of the concrete specimen are resulted from computational work of DIA. Credit: Korea Institute of Civil Engineering and Building Technology (KICT)

It also has the added benefit of simulating scenarios for fire forensic specialists to investigate when and how the fire started.

The patent for F2IS was approved in August. The team plans to develop a rehabilitation system that can chemically cure the decomposed hydration products to fill in the cracks and help the structure recover.

3 reproducing thermal diffusivity after fire exposure
With information of time-temperature curves resulted from DIA, 3D thermal diffusivity is re-produced. Commercial program of ‘Comsol Mutiphysics’ is used for this simulation work. Location of fire source and thermal spread are traced without pre-installed sensors after fire exposure. Credit: Korea Institute of Civil Engineering and Building Technology (KICT).

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