MAKING CONCRETE.

Lyttelton Times, Volume CXV, Issue 16606, 18 July 1914, Page 6

MAKING CONCRETE.

In answer to an inquiry about the best way of making good concrete for cow house flooring, silo building and liko purposes, Mr A. R. Ferguson, a Victorian, explains:— " There aro several ways of hand' mixing concrete, but the following ; method gives sati c factory results. In the first place I would recommend that 'a mixture of ono part Portland cement, two parts clean sand, and four parts crushed reck or pebbles bo used for the concrete. The crushed rock or pebbles should vary in sire from onefourth inch to throe-fourths inch. "A watertight mixing platform should first bo built. For a two-bag batch, that is, a batch using two bags of cement, a convenient size platform is 10ft square. It should be made of one-inch boards 10ft long, surfaced on one side, using five cleats to hold the boards together. The cleats should bo of two-inch by four-inch material. Tho of surface boards ensures ease in shovelling, and tho boards should be laid so as to enable the shovelling to ho done with and not against tho cracks between tho boards. The boards j must be drawn up closo in nailing, so that no will occur. It is well , nl~o to have a two-inch by two-inch j strip around the ode:e of tho platform to prevent : tbo escape of water. " If successful results are to be obtained in any concrete work, tho sand j and stono must be correctly measured ■ for each batch. For the two-bag batch i we have referred to, four cubic feet of sand and eight cubic feet of stone would , lie required. In order to make this | measurement accurately, a bottomless j measuring box of a convenient size | should be constructed. By making this j box two fest square and one foot deep, filling it onco wuh sand and twice with stono, tho proper amounts of each will | be obtained. The sand and cement ! should first be mixed together dry until a uniform mixture results. The ce- i ment should not show in streaks in the sand, as this indicates an uneven dis- ' tribution. Turn the mixture of sand and cement over with shovels until a j uniform colour is obtained. Now spread this sand and cement in a layer about j four inches deep over_ one end of tho mixing board. Upon it place the four j cub'c feet of stono. j *' In measuring the stone tho box can I be placed directly upon the sand and , cement mixture and filled, then lifted, j leaving tho stone in position to be mix- ■ ed. CK™ water is now added. The j water should be free from vegetablo matter and acids. A total of nhoutlO i gallons of water will be needed to bring | the concrete to the conn'rteney, | but this should be poured over the stone j a little bit at a t'me «« the mixing pro- j grosses. Turn the whole nw»ss of ce- j ment. sard and stone bv shoveWne from , either Hde of the pile until there is an absolute uniform mixture." j