CONCRETE FLOORS.

King Country Chronicle, Volume III, Issue 153, 6 May 1909, Page 4

CONCRETE FLOORS.

! Concrete floors may be divided into I two classes: Those which rest immediately upon the ground, as a cellar or basement floor, and those supported by girders and made in the form of slabs with metal reinforcement. The limits of the present article confine us to a description of the first kind. The floor consists essentially of three parts—first the porous foundation which rests upon the ground and provides drainage, thus insuring against the heaving of the floor by frost in freezing weather; second, the body which furnishes the strength to the floor and supports the third part, the surface which receives the wear. The first may be of cinders or clinkers.or coarse gravel or stone chips, well bedded and tamped. The second U of Portland Cement concrete. The third is a mixture of Portland cement and sand, or crushed stone. Each part is equally important, and performs its functions best when made of the materials mentioned. For the foundation provide cinders or clinkers free from ashes, slag, stone chips, or cleans coarse gravel of such size that it will pass through a three inch ring, and the ' smallest pieces will just pass through a one inch ring, j Concrete consists of two parts, the matrix, consisting of mortar composed of Portland cement and sand or crushed I stone, and the aggregate composed of i broken stone or gravel. The function i of the matrix is to cover each particle [of the aggregate with mortar, and to I fill all the voids or spaces in the ag- | grcgatc and bind all the separate par- ; tides composing it together into one ; solid mass. i The Best Cement. The only cement suitable to use is a j reliable brand of Portland cement, I Many excellent brands of local Port- \ land cement are not only cheaper but ! better than most of the imported ce- | ments. It is neither necessary nor adi visable to buy an expensive cement. j When large quantites of cement are 1 to be used it is customary to make j elaborate tests. The standard specifi- ! cations for cement supplied by the [ American Society for testing materijj als, have been almost universally I adopted by the Portland cement manu- ! facturers. Reliable brands will pass j these specifications. It is hardly pracf ticablc for the farmer to make these ■ tests, and he must rely largely upon the reputation of the brand which he buys. The time before which setting takes place is an indication of the j quality, and may be roughly performed as follows:—Take about Jib of cement and mix to a stiff paste with water, rolling it into a ball with the hands then put it on to a plate. It should show indications of setting in half an hour, but should not set hard before one hour has elapsed, nor later than after ten. Trial from time to time with a pencil point will indicate how the setting is progressing. The paper bag is the best form of package in which to buy the cement, as less moisture will be absorbed through it than through cloth, and no charge is made for the bag, while ten cents are charged for each sackcloth not returned in good condition. But little cement is now sold packed in barrels. Reject all bags that contain lumps. The eminent has absorbed moisture and its value is impaired. Any coarse, sharp sand may be used. It should be quite free from clay loam, vegetable fibre or any other foreign substance. The size should be such that it will pass a No. 4 screen, and the bulk of it sholud be coarse rather than fine. The number of a screen is the number of meshes per lineal inch. The coarse and fine together arc better than either alone. Crushed stone of ! the same size may be substituted for sand with excellent results.