Concrete is the most widely utilized construction substance worldwide with an average global annual consumption of 1m3 per person. Fire is one of the finest serious potential risks to numerous concrete structures like tunnels, buildings and bridges. While concrete is known to be a substance with great fire – resistance, potential of retaining much of its load – bearing capacity, its chemical, mechanical and physical properties do undergo serious modifications when subjected to big temperatures. A major loss in strength occurs when concrete is heated above 300 Degree Celsius.
A structural security assessment offers information required to evaluate the residual bearing capacity and strength of fire – damaged concrete structures. They are also utilized to propose the suitable repair methods or to decide if demolition is required. There are numerous traditional on – site and off – site methods for assessing fire – damaged concrete. Most of the on – site techniques comprise visual inspections of colour change and physical features like off – site methods involve invasive experiments like core drilling or lab based methods, but all techniques have their drawbacks and merits.
Wallace Mukupa, a PhD student at the Nottingham Geospatial Institute at UNNC and a reader in Geospatial Engineering at the University of Nottingham, and Criag Hancock studied the utilization of terrestrial laser scanning as a non – destructive method to assess and identify fire – damaged concrete in a structural safety appraisal. Wallace says, “Scanning can be performed at a distance that enhances site safety. Scanning is also effective with numerous points estimated in a few seconds and spatial resolution obtained in short time. It is beneficiary for structuring structures considering their scale or magnitude.”
A non – destructive method for health assessment of fire – damaged concrete substances utilizing terrestrial laser scanning was introduced in this study. The study further investigated the influences of scanning incidence angle and distance on the laser intensity returns. Concrete colour alter was also examined. Information was gathered and analysed on unheated and heated concrete to establish the baseline condition of the substance.
The concrete specimens were heated in a container to high temperatures of up to 1,000 Degree Celsius as the temperature obtained is a vital factor in assessing fire – damaged concrete. To analyse the colour changes in the heated concrete, specimen pictures were captured with help of M-cam linked to a scanner. During the study, the estimation of the incidence angles for the concrete blocks was identified to vary with distance. As the scanning distance enhanced, the incidence angle reduced and both scanners revealed the same trend.
The study has also revealed that RGB data enhances the visual identification of features and offers s rough idea of the concrete condition after a fire. Laser scanners have a benefit in that most of them have either an external or an internal camera that can be utilized to capture concrete images of good resolution.
Filed Under: News