Cement houses and how to build them. . andsmoothing the tops with a trowel. Themolds should be oiled slightly to preventmortar from sticking. Put the mold awayin a cool and, if possible, damp place fortwenty-four hours. Then remove theprisms of mortar and place them in freshwater, neither hot nor cold, for six or fortwenty-seven days. Any prisms that are chipped or otherwise defective should bediscarded. Make the apparatus shown inFig. 3 with a board, a round piece of woodabout an inch in diameter, and a pail. Thebottom knife edges are made by cutting theround piece of wood in half, and are fa
Cement houses and how to build them. . andsmoothing the tops with a trowel. Themolds should be oiled slightly to preventmortar from sticking. Put the mold awayin a cool and, if possible, damp place fortwenty-four hours. Then remove theprisms of mortar and place them in freshwater, neither hot nor cold, for six or fortwenty-seven days. Any prisms that are chipped or otherwise defective should bediscarded. Make the apparatus shown inFig. 3 with a board, a round piece of woodabout an inch in diameter, and a pail. Thebottom knife edges are made by cutting theround piece of wood in half, and are fas-tened to the board exactly 10 inches apart,center to center. The center knife edge isa round piece of wood from which a pailis suspended by a cord. When the test pieces are seven or twen-ty-eight days old place them, still wet, onthe apparatus as shown in the cut, takingcare that the upper strip is exactly in thecenter and at right angles with the the pail so that it is just off theground and exactly under the specimen,. Fig. 2—Method of testing strength. and then slowly pour sand into it until theprism breaks. Carefully weigh thebucket with the cord and strip still at-tached. If the prism is not exactly oneinch square, correct the weight by dividingit by the product of its width times thesquare of its depth in inches. The approximate strength of the mortarmay then be computed as follows: Tensile strength equals center load mul-tiplied by 10. Compressive strength is load multipliedby 50. If the average of three prisms tested inthis manner shows a tensile strength ofless than 120 pounds at seven days or 180 CEMENT HOUSES AND HOW TO BUILD THEM. 11 pounds at twenty-eight days, on 1:3 mor-tars, something is radically inferior andwrong with either the cement or the sand,and the fault should be thoroughly inves-tigated. Tests made by this method are, ofcourse, far from being accurate, but theynevertheless give a very fair indication ofthe value of the material. In de
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectdomesticarchitecture
