Increasing Cold Weather Masonry Construction Productivity

744955PDFResearch PaperCRREL-SR-97-16Cold weather constructionMortarMasonry constructionMoisture contentFreeze thaw durabilityCortez, Edel R.Korhonen, Charles J.Thomas, Robert D.Cold Regions Research and Engineering Laboratory (U.S.)NTL-HIGHWAY/ROAD TRANSPORTATION-HIGHWAY/ROAD TRANSPORTATIONNTL-HIGHWAY/ROAD TRANSPORTATION-Construction and MaintenanceNTL-HIGHWAY/ROAD TRANSPORTATION-MaterialsUS Transportation CollectionThe thermal protection requirements for cold weather masonry, as established in current industry specifications, were evaluated. Experiments were conducted to define the most relevant factors in the process of freezing of newly placed mortar. The effect of unit absorption on the moisture content of mortar during the first hours after assembly was assessed. Correlations of moisture content with time were developed for mortar in contact with masonry units. Frost immunity thresholds in terms of mortar moisture content and in terms of maturity were determined. The test results provided the basis for new proposed guidance on when fresh mortar can be safely exposed to freezing temperatures. Test methods for evaluation of the freeze-thaw resistance of masonry units were evaluated. A new test was proposed and adopted by ASTM as a new standard test for the freeze-thaw testing of masonry units. In addition, several chemicals were evaluated for their potential as antifreeze admixtures for masonry mortar. Antifreeze admixtures were first developed for use in concrete, but the practicality of using antifreeze admixtures in masonry mortars was demonstrated in a field application in Michigan during the winter