A study of strength fluctuations of Portland cement by FTIR spectroscopy
Evgeny V. Tararushkin, Tatiana Shchelokova, V. D. Kudryavtseva
Abstract
Abstract The study of daily tests (1-28 days) for compressive strength of ordinary Portland cement is presented. The daily strength curves were obtained for two water cement ratio (W/C=0.4 and W/C=0.5). On both curves, intervals with strength fluctuations were identified. For cement paste with W/C=0.4, one interval with fluctuations was detected (13th-18th days), for cement paste W/C=0.5, two intervals with fluctuations were detected (13th-17th days and 21st-25th days). The largest value of decrease in average strength for samples with W/C=0.4 is -7.1 MPa, for samples with W/C=0.5 the largest value of decrease in average strength is -2.7 MPa. For cement paste samples with W/C=0.4 for 15th-18th days, infrared spectra were obtained by Fourier-transform infrared spectroscopy. The analysis of the FTIR spectra showed that the strength fluctuation may be caused by the formation of a sulfate phase (ettringite) during hardening of the cement paste.