Characterization and deterioration detection of Portland cement concrete using ultrasonic waves

An experimental study was conducted to characterize Portland cement concrete (PCC), to detect deterioration induced by freeze/thaw and alkali-silica reaction, and to detect chloride presence in PCC using ultrasonic waves. The experimental program was initiated to investigate the effect of water to cement (w/c) ratio, aggregate type, and air entrainment on measured ultrasonic wave velocity and signal energy. Three w/c ratios (0.35, 0.45, and 0.55) were evaluated. Two aggregate types, quartzite and limestone, were included in the PCC mixes separately. Mixes were prepared as non-air entrained and air entrained. Thus, a total of twelve batches were prepared to evaluate PCC using ultrasonic waves at two frequencies, 54 and 340 kHz.; The experimental program to investigate freeze/thaw (FT) damage included the effect of curing time, w/c ratio, and aggregate type. The effect of curing time was investigated by exposing PCC specimens cured for 3 and 7 days to FT. Two w/c ratios were considered, 0.45 and 0.55. The effect of aggregate on detecting FT damage was investigated using two types of crushed stone aggregate, quartzite and limestone. Alkali-silica reaction (ASR) damage was investigated using two w/c ratios, 0.35 and 0.45. Embedded composite strain gages were used to monitor the ASR deleterious deterioration. High alkali cement and active silica aggregate were used to produce ASR.; Chloride contamination of PCC was accomplished using two methods: in the first method, chloride solutions were used in preparing PCC mixes. Three chloride concentrations were used: 1.19, 2.37, and 4.75 kg/m{dollar}sp3{dollar} of PCC. Ultrasonic measurements were taken over curing time. Powdered PCC samples were collected at 28 days of moist curing to measure the exact chloride content. The second method involved immersing PCC specimens in 6% (by weight) chloride solution. Ultrasonic measurements and powdered PCC samples were taken every two months.; The least significant difference (LSD) statistical test was used to compare the effect of different PCC properties and deterioration on measured ultrasonic velocity and signal energy. The study showed that signal energy is more sensitive than the apparent ultrasonic wave velocity to characterize PCC and to detect deterioration. Aggregate type was found to have a significant influence on ultrasonic waves propagating in PCC. Two modes of waves appear to propagate in PCC using direct and indirect methods. The direct method appears to produce non-dispersive wave mode while the indirect method appears to produce dispersive wave mode. Apparent ultrasonic wave velocity was found to increase with curing time. The effect of w/c ratio and air entrainment on signal energy was significant. Both the apparent ultrasonic wave velocity and signal energy were able to detect FT damage in PCC. The signal energy was sensitive to ASR deterioration while apparent ultrasonic wave velocity was unable to detect any ASR damage. Chloride content, on the other hand, was undetected by apparent ultrasonic wave velocity, and by signal energy analysis.