Masonry Magazine December 1995 Page. 11
Hot & Cold Weather Masonry Construction
Masonry construction can and should continue regardless of weather conditions, with proper prior planning. Because weather does affect the performance of masonry materials and the rate of masonry construction, it's important to understand weather effects and prevent or lessen their influence.
BY AL ISBERNER, PE
Consulting Materials Engineer
The desire to continue masonry construction throughout the year leads to concerns regarding the performance of the masonry under adverse climatic conditions. Cold Weather Masonry and Hot Weather Masonry have received recent interest with several articles stipulating practices, which should be followed. Masonry construction can and should continue regardless of weather conditions, with proper prior planning.
Because weather does affect the performance of masonry materials and the rate of masonry construction, it's important to understand weather effects and prevent or lessen their influence. Weather information, nationwide and locally, has become more accurate during the past decade. Three day forecasts are classed as very accurate: long term predictions are superior to those available in the '70's.
During any discussion of weather effects, terms like "normal," "hot," "cold." and "other" are frequently used to identify the prevailing weather condition or construction boundary conditions. These terms are classed as relative, with no precise assignment of temperature or humidity possible. Throughout this paper. "normal" implies temperature and humidity conditions common to a geographical area, during a particular season. Other weather conditions are above or below the "normal" conditions.
Sensitivity of Materials
Generally all masonry construction materials are influenced by climatic conditions. These materials are sensitive to both temperature and moisture/humidity changes. Portland cement and masonry cement react with water; both temperature and available moisture influence the rate and degree of cement hydration. Hydrated lime reacts with water and carbon dioxide in the atmosphere to produce a denser mortar.
Mason's sand normally contains free moisture, which freezes during cold weather and promotes some evaporative cooling during hot dry weather. Clay masonry units absorb water and the absorbed water freezes during cold weather. Concrete ma-