Cement houses and how to build them. . and of Different Stones. Differentstones of the same class vary so widely thatit is impossible to give any hard and fastrule as to their exact comparative valueswhen used in concrete. A comparison bytests with a large number of different kindsof stone indicates that the value of abroken stone for concrete is governedlargely by the actual strength of the stoneitself, the hardest stone producing thestrongest concrete. Comparative tests in-dicate that different stones in the order oftheir value in concrete are approximatelyas follows: 1, trap;
Cement houses and how to build them. . and of Different Stones. Differentstones of the same class vary so widely thatit is impossible to give any hard and fastrule as to their exact comparative valueswhen used in concrete. A comparison bytests with a large number of different kindsof stone indicates that the value of abroken stone for concrete is governedlargely by the actual strength of the stoneitself, the hardest stone producing thestrongest concrete. Comparative tests in-dicate that different stones in the order oftheir value in concrete are approximatelyas follows: 1, trap; 2, granite; 3, gravel;4, marble; 5, limestone; 6, slag; 7, sand-stone; 8, slate; 9, shale; 10, difficulty in the way of an accuratecomparison is the variation in the ages ofstone of the same classes. The value of CEMENT HOUSES AND HOW TO BUILD THEM. 33 sandstone is not more than three-fourthsof the value of trap and the value of slateis less than half that of trap. Good cindersnearly equal slate and shale in Fig. 2S—General details of construction from founda-tion to the first floor level. Selection of Stone. The quality of theconcrete is affected by the hardness of thestone. In all cases porous stone like sand-stone should be avoided. The shape andsize also have their influence. If brokenstone is used the best is that which is hard jwith cubical fracture; with particles whosemaximum size is as large as can be handled in the work; with the particles smallerthan, say, % inch screened out, and withthe sizes of the remaining coarse stonevarying from small to large, the coarsestpredominating. Hardness of Stone, The hardness ofthe stone grows in importance with the ageof the concrete. Thus gravel concrete, be-cause of the rounded surfaces, at the ageof one month may be comparativelyweaker than concrete made with compara-tively soft stone, but in a year it may sur-pass in strength the concrete made withbroken stone, because as the cement be-comes hard the
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectdomesticarchitecture
