Soon after the mortar acquires its initial set and before it acquires its final set, the joints should be raked out to a depth from the face of two to three times the thickness of the joint. The refilling and pointing of the joints should be deferred as long as possible, for it is well known that a mass of masonry continues to settle for some time after being built, and the pointing is more effective if there is little or no subsequent settlement of the masonry. (See Settlement of Masonry.) Unless it be desired to refill loose material against the masonry or to raise the water level on the upstream side, it would be better to let all of the pointing wait until the dam has otherwise been completed for some time. In advance of the pointing, the joints should be thoroughly cleaned of any dirt or loosely adhering cement, and washed out with a hose. The joints should be filled with a mortar somewhat richer in cement than is necessary for the body of the work. The mortar should be used quite dry, say of the consistency of laboratory practice in making briquettes, and it should be thoroughly rammed and caulked into the joint. When the joint is completely filled the mortar should be rubbed down with a convex tool nearly the width of the joint in order to produce a practically flush but slightly concave joint. This last process slightly consolidates the face mortar and gives the joint a neat, accented, finished appearance. If possible the work should be done in cool, cloudy weather; or if exposed to the sun, or to conditions such that the mortar is liable to dry out before properly setting, the pointing should be protected by wet gunny sacks. Water in such quantities as would wash out any of the cement must, of course, be kept from the area which is being pointed.
Owing to the fact that pointing is usually done at odd times, as the weather conditions are favorable or as men may be available from other parts of the work, the cost of the work is difficult to ascertain, and it has rarely been observed with any accuracy. At the New Croton dam all the pointing was left until the end of the work. The joints were 1/2 in. in thickness, were raked out to a depth of 2 in. and were pointed with 1 to 1 Portland cement mortar. The average cost of pointing 326,500 linear ft. of joints was 5 cents per lin. ft. Wages not stated but probably most of it was $3 per eight hours. One bag of cement was required for every 100 ft. of joint.
Care should be taken to rake out the joints to the full depth at the proper time, as the cost is very materially increased if much mortar is left to be chiseled out when the pointing is done. The cost of pointing a thicker and deeper joint would not be in proportion to the size except in the matter of materials, and that is a small part of the total. Probably 10 per cent, to 15 per cent, of the cost is in rigging and moving the necessary stagings. The cost of cleaning out the joint would not be more than proportional to the depth (within range of actual practice) of the joint. Even if some of the raking out had been overlooked and the joint had been left full of mortar, the cost of cutting it out would not be in proportion to the amount actually removed. Then for the cost of pointing a joint 2 in. thick X 3 in. deep, as at the Roosevelt dam, multiply materials by six, labor by two to two and a half, and, for intermittent work add possibly 10 per cent, to the labor.