Deicing salt scaling resistance of concrete incorporating supplementary cementing materials: laboratory and field test data

Abstract

In this study, sidewalk sections were made in the field using seven concrete mixtures, applying a finishing and curing practice that is commonly used in Montréal, Canada. For each of the sidewalk sections, large slabs (1.2 m × 1.2 m) were cast from which specimens were cored and tested in the laboratory for determining their basic mechanical properties and deicing salt scaling resistance following ASTM C672 test procedures. Also, during the casting of the sidewalk, companion specimens were cast on site, using concrete from the same batch, and were subjected to the same tests as the “cored” specimens. The resistance to deicing salt scaling of these “laboratory specimens” was evaluated according to ASTM C672 and to BNQ NQ 2621–900 (2002 standard of the province of Quebec, Canada) test procedures. The results were compared with the performance of the sidewalk sections after four winters of outdoor exposure. The visual evaluation of the sidewalks after four winters has confirmed the severity of the ASTM C672 procedure and the adequateness of the BNQ procedure to better evaluate the deicing salt scaling resistance of concrete made with supplementary cementing materials (SCMs). The field evaluation should, however, continue for a longer period of time to increase the confidence in the BNQ test or to allow for changes as needed.

Deicing salt scaling resistance of concrete incorporating fly ash and (or) silica fume: laboratory and field sidewalk test data

“…However, when the specimens were tested according to BNQ procedure (BNQ 2002), the fly ash concrete VF2 still showed more scaling than the control concrete but the difference is much less than for the ASTM test. This is in line with the results presented in Part I of the study (Bouzoubaâ et al 2008).…”

“…Whereas, when these laboratory samples were tested for scaling resistance according to BNQ NQ 2621-900 (standard of the province of Quebec, Canada) test procedure (BNQ 2002), the results have shown similar performance as that observed on the sidewalks. The results have confirmed the severity of the ASTM C 672 procedure and the adequateness of the BNQ procedure to better evaluate the deicing salt scaling resistance of concrete incorporating supplementary cementing materials (SCMs) (Bouzoubaâ et al 2008).…”

“…All the concrete mixtures had a spacing factor lower than 200 µm, which is considered satisfactory to provide adequate resistance against freezing and thawing cycles in Canada. However, as mentioned in the previous study, it is possible that the spacing factors at the surface of the slabs have different values than those presented in Table 6 due to the finishing and curing operations (Bouzoubaâ et al 2008).…”

“…A previous study on sidewalk sections cast in the spring of 2002 using seven concrete mixtures incorporating up to 35% fly ash or slag proved the satisfactory performance of these concretes after four winters in the field (Bouzoubaâ et al 2008). Laboratory samples cast from the same concrete mixtures and tested for scaling resistance following the ASTM C 672 test procedure (ASTM 2003) have shown poor performance in all cases.…”

“…This is most likely due to the relatively low ambient temperature that is generally experienced during that period of the year. When the same concrete mixtures were made in spring (ambient temperature around 27°C during the day of casting), the difference between the compressive strength determined on cores and that determined on cylinders was very small (Bouzoubaâ et al 2008). It appears that for the control concrete (no fly ash added), the effect of the low temperature was negligible.…”