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

Abstract

Sidewalk sections were cast in fall 2002 with three concrete mixtures that consisted of a control concrete, a concrete mixture incorporating 25% fly ash, and a concrete mixture made with a ternary blended cement (fly ash and silica fume). The curing practices consisted of using curing compound and wet burlap. For each of the sidewalk sections, laboratory specimens were cast on site using the concrete from the same batch. Large slabs (1.2 m × 0.9 m) were also cast from which specimens could be cored and tested in the laboratory for compressive strength and deicing salt scaling resistance following the ASTM and the BNQ test procedures. The results were compared to the performance of the sidewalk sections after six winters of outdoor exposure. A similar study was completed on sidewalk sections cast in spring 2002; the objective of the present study being to confirm the results of the previous investigation, and to determine the effect of the time of casting on the scaling resistance of the concrete i.e., performance of sidewalks cast in spring versus that of sidewalks cast in fall. The field evaluation showed that all the concretes cast in fall scaled relatively more than those placed in spring. Both laboratory results and field evaluations have shown that the use of a curing compound increases the scaling resistance of all the concretes investigated. The results also confirmed the adequateness of the BNQ procedure to better evaluate the deicing salt scaling resistance of concrete made with supplementary cementing materials; however, monitoring the sidewalk sections for a longer period of time is still required to confirm the above observations. Résumé : Des sections de trottoirs ont été fabriquées à l'automne 2002 en utilisant trois mélanges de béton : un béton de contrôle, un mélange de béton incorporant 25 % de cendres volantes et un mélange de béton fabriqué d'un mélange ternaire (cendres volantes et fumées de silice). Les pratiques de cure consistaient en l'utilisation d'un produit de cure et d'une toile de jute mouillée. Pour chaque section de trottoir, des échantillons de laboratoire ont été coulés sur place en utilisant du bé-ton provenant du même mélange. De grandes dalles (1,2 m × 0,9 m) ont également été coulées, des carottes y ont été préle-vées et testées en laboratoire afin de déterminer la résistance en compression et la résistance à l'écaillage causé par le sel de déglaçage selon les procédures ASTM et BNQ. Les résultats ont été comparés au rendement des sections de trottoir après six hivers d'exposition. Une étude similaire a été complétée sur les sections de trottoir coulées au printemps 2002. L'objectif de la présente étude était de confirmer les résultats de l'étude antérieure et de déterminer l'effet du moment de la coulée sur la résistance à l'écaillage du béton, c.-à-d. le rendement des trottoirs coulés au printemps par rapport à celui des trottoirs coulés à l'automne. L'évaluation sur le terrain a montré que tous les bétons coulés à l'automne s'écaillaient relativement plus que ceux mis en pl...

Frost resistance of concrete with high contents of fly ash - A study on how hollow fly ash particles distort the air void analysis

“…The problem becomes larger, when the fly ash dosage increases. Both [8] and [9] show that the salt frost scaling of concrete with high volumes of fly ash is reduced significantly, if the start of the freeze/thaw exposure is postponed to 91 or 180 days after casting.…”

A study into the effects of test variables on the results of concrete tests for salt scaling and alkali-silica reaction

“…The curing regime consists of the same initial curing procedure as ASTM C672 and MTO LS-412 but requires on additional step before freeze thaw cycling can take place. This step requires the re-saturation of the surface using a 3% NaCl solution and is meant to partially simulate the field conditions of new concretes exposed to low concentration salt solutions during a first winter (Bouzoubaâ et al, 2011).…”

“…In terms of solution and flushing the BNQ follows the procedure of the MTO LS-412 in that a 3% NaCl salt solution is used as the ponding as agent during freeze-thaw cycling and for the flushing process. Bouzoubaâ et al (2011) note that the ASTM C672 does provide for the use of other salt solutions. Finally, the BNQ procedure does differ slightly in the schedule for the removal of the scaled particles.…”

“…Finally, the BNQ procedure does differ slightly in the schedule for the removal of the scaled particles. The test requires a 7 day a week freeze-thaw cycling procedure from which scaling residues are collected at 7, 21, 35, and 56 cycles (Bouzoubaâ et al, 2011).…”

Salt Scaling of Pervious Concrete: Optimizing a Test Method and The Effects of Different Deicers

“…The influence of supplementary cementing materials on salt scaling has been tested by a number of researchers. It was found that the use of fly ash or slag would greatly increase the damage caused by salt scaling (Bouzoubaa et al, 2008(Bouzoubaa et al, , 2011Boyd and Hooton, 2007;Nili and Zaheri, 2011;Ahani and Nokken, 2012;Gagné et al, 2011;Duos and Eggers, 1999;Afrani and Rogers, 1994;Chidiac and Panesar, 2008). The range of replacement varied from 15% up to 50%, with higher levels replacements generally suffering more damage.…”