Table 5: Ratios of peak area (AS) and peak height () from the FTIR spectra of brick specimens at Si–O–Si stretching vibration.

Sample codeURHA content (%)Si–O–Si location (cm−1)AS ratio ratio

P35U00010781.0001.000
P35U101010840.9770.952
P35U202010860.0340.128
P35U303010880.0310.115
P35U404010910.0290.106