Masonry Magazine November 1965 Page. 10
Cold & Hot Weather Aspects of Mortar
After the mortar is mixed, we recommend the mortar temperature of not over 120° F. If our water is 160° F., our cold sand will pull the temperature down, and it should be above 70° F. Another recommendation we make between the temperature of 40° and 32° is that freshly laid masonry should be protected from an overnight freeze. Covering with tarps, insulation bats or straw is adequate protection.
For temperature ranges between freezing but above 20° F., we recommend that all of our previous points should be followed plus two additional requirements. One is that the sand should be heated. Sand can be heated very easily by dumping the stockpile of sand over a piece of culvert material and building a fire in the culvert material. A second requirement for this temperature range is that the working area should be enclosed and heated with space heaters. A minimum temperature of 50° F. should be maintained within the enclosure for 48 hours. The purpose for enclosing and heating the working area is twofold. First of all, it will keep hard and cold winds off the freshly laid masonry work. Plus, it will improve the efficiency of the workers. At temperatures between 20° and freezing it is very difficult for the worker to be comfortable while working out in a cold wind. The cost of an enclosure is often offset, or more than offset, by an increased efficiency in the masons.
For temperatures below 20° F. but above zero all of the previous points should be followed and one additional requirement is added. We recommend that for this temperature range masonry units should also be heated. A convenient way to heat the masonry units is to stockpile them on wooden sleepers or stringers between each layer. Units with hollow cores should be placed with the cores horizontal. Cover the stockpile with a tarp so that in effect a kiln-like arrangement is contrived. A space heater can be placed at one end of this arrangement and hot air blown through the stockpile of masonry units.
For temperature below 0° F. we recommend that only emergency work be undertaken. All of our previous requirements should be very rigidly followed. Incidentally, if you have a client who is willing to pay the added cost of rigidly following all of the requirements we have stated, I would classify this as an emergency.
In cold-weather construction it is more important to plan in advance than it is for conventional construction. During the construction season when temperatures are favorable, it is fairly easy to change plans at the last minute and make variations on the job and so forth. Variations such as this are very difficult and sometimes impossible when it involves enclosed working areas, space heaters, etc. Planning in advance can oftentimes eliminate many of the headaches that may be encountered in cold-weather construction.
For cold-weather construction it is important that the maximum efficiency be obtained for the mason with as little detracting from his output as possible. This, of course, is important at all times but in cold weather it takes on added significance. If we use a mortar that is consistent in all of its physical properties, this will