Remarks

This Table shows (1) that the coarsely ground cement broke at a higher point when used neat than when finely ground or sifted, but at a much lower point when mixed with sand : (2) that at 25 weeks with 3 of sand the gain was equal to 41 per cent, and with 5 of sand equal to 64 per cent; (3) that the strength of the fine cement with 5 of sand was equal to a greater strain than that of coarse with 3 of sand, especially at the earlier stages. The proportion remaining on a sieve of 5000 per square centimetre (32,257 per sq. inch) was 495 per cent. - J. G.

The resistance of Portland cement to crushing after nine months is greater than that of most building materials, being 3 tons per square inch.

1 Grant's Experiments. 2 From M.P.I.C.E, vol. lxii. p. 149 (Grant).

Table1 Showing The Tensile Strength Of Various Limes, Selenitic And Portland Cements

TABLE1 showing the Tensile Strength of various Limes, Selenitic and Portland Cements, with different proportions of Sand at the end of 12 months. Five of the Briquettes kept dry and five in water. Size 1 1/2" x 1 1/2"=2 1/4 square inches. Form as in Fig. 84, page 174. Sand 96 lbs. per bushel.