Effects of antifreeze admixtures on masonry performance at subfreezing temperatures

Concrete brick prisms prepared with Type S masonry mortar that included sodium nitrite and/or nanocellulose as potential antifreeze admixtures were cured for 28 days at −10 °C before measuring compressive and flexural bond strengths. Addition of sodium nitrite allowed masonry prisms cured at −10 °C to reach 88% and 86% of the compressive and flexural bond strengths, respectively, of control specimens cured at room temperature. Nanocellulose was only effective when used in combination with sodium nitrite, improving the compressive and flexural bond strengths by an additional 3% and 27%, respectively. Results are primarily attributed to the ability of the sodium nitrite to lower the freezing point, allowing hydration to continue in subfreezing conditions, as confirmed by results of companion tests on mortar samples. Both additives also reduced the required w/ c ratio and porosity. The findings offer a sustainable alternative to energy-intensive protective heating methods, potentially lengthening the construction season into colder periods.