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Outdoor Problems of the Householder: Portland

Cement.-Buy, preferably, Portland cement in cloth sacks, rather than in paper bags or wooden barrels. Keep dry until ready for use by storing on boards raised from the floor by means of wooden blocks and covered with canvas or roofing paper. Keep indoors in a dry place.

Otherwise cement will absorb moisture from the atmosphere and become lumpy or often a solid mass. Such cement is worthless and must be thrown away. But lumps caused by pressure may be easily broken up and such cement is perfectly good. Dry cement mixed with water forms a soft sticky paste. This begins to "set" or harden in about half an hour. Any disturbance of concrete after it begins to set weakens it, or if the set is well under way, destroys it. Hence, Portland cement concrete must be mixed in small quantities, as needed, and placed in position within twenty or thirty minutes after first being wet.

Cautions.-Avoid extremes of heat.

Portland cement concrete is weakened by exposure to a hot sun during the first four or five days after being placed in position. Or it may be injured by freezing while being mixed and before being placed in position, or even after having been placed, if subjected to a heavy load.

Hence, avoid mixing in freezing weather, i. e., if the temperature is below 32° F. Do not cover when green with fresh manure to protect it from freezing as this will soil the surface and weaken the concrete.