A thermoanalytical, X-ray diffraction and petrographic approach to the forensic assessment of fire affected concrete in the United Arab Emirates

Abstract

A thermoanalytical, X-ray diffraction and petrographic approach to the forensic assessment of fire affected concrete in the United Arab Emirates Alqassim, M. A.; Jones, Martyn; Berlouis, L. E. A.; Nic Daeid, Niamh General rightsCopyright and moral rights for the publications made accessible in Discovery Research Portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from Discovery Research Portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain.• You may freely distribute the URL identifying the publication in the public portal. Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. KeywordsForensic investigation; Concrete; Fire; Thermal Analysis; X-ray Diffraction; Colour Change. Highlights• This work studies the application of thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction and petrography as tools for revealing the thermal history on concrete structures.• • Other reactions can be reversible, particularly the dehydroxylation of Portlandite.The thermal history can still be determined though by comparing the onset temperature of reformed components with Portlandite in non-previously heated samples.

Effect of Elevated Temperature on Meso- and Micro-Structure and Compressive Strength of High-Strength Concrete and Mortar Containing Blast-Furnace Slag

“…The diffraction peak intensity of Ca(OH) 2 (2θ = 18.08° and 34.12°) had no obvious change with the increasing temperature from 20°C to 400°C. However, this peak intensity was eliminated after 600°C nearly, similar to what was observed by Alqassim et al (2016) and Delhomme et al (2012). On the other hand, it was worth noting that the diffraction peak intensity of CaO (2θ = 37.42°) appeared after 600°C and it increased with the increasing temperature.…”

“…A similar tendency for NSC with 0% and 20% BFS was also observed by Siddique and Kaur (2012). Different from reports of Alqassim et al (2016) and Siddique and Kaur (2012), Poon et al (2001) found that the residual compressive strength increase occurred when HSC with 30% and 40% BFS was subjected to 200°C, yet after 600°C, the residual compressive strength drastically reduced by about 40% -50% compared to that at room temperature. According to the above discussion and the result reported by Sanjayan and Stocks (1993), HSC containing BFS will appear to be inferior elevated temperature resistance as compared to NSC containing BFS.…”

“…3 and 4 and loose micro-morphologies shown in Fig. 6, which became the main reason for the degradation in residual compressive strengths of HSC and HSM (Alqassim et al 2016;Mendes et al 2012).…”

“…A few researchers have studied the effect of elevated temperature on properties of concrete containing BFS, in particular the residual compressive strength as the most important index for evaluations of mechanical properties, designs of new structures and assessments of conditions of existing structures (Mahmod et al 2016). Alqassim et al (2016) suggested that for NSC with BFS replacement ratio of 50% by weight, the elevated temperature of below 600°C cannot cause the obvious compressive strength loss and even leaded to a constant strength increase of up to 119.3% compared to that at room temperature. For the influence of BFS, NSC with 50% BFS exhibited greater strength than that without BFS after the same elevated temperature.…”

Fibers and fiber cocktails to improve fire resistance of concrete

“…show that there was a considerable reduction of both flexural strength and residual flexural strength in the temperature range of 500 and 800 °C, which can be mainly explained by the chemical changes of concrete in this temperature region [25][26][27]. Possible reasons can be reactions in the cement stone such as dehydration of Ca(OH)2 below 500 °C, and decomposition of CSH (calcium-silicate-hydrates) and CaCO3 between 500 and 800 °C.…”