XIII, A, 1 



Witt: Cew.ent and Concrete 



37 



of sea water on cement. It has been shown for some cements 

 that the iron content is one of the factors which determines 

 the effect of sodium sulphide.^ 



This paper presents experiments that have been undertaken 

 in an effort to correlate investigations in this field of research. 



EXPERIMENTAL WORK 



Two barrels each of four brands of cement were chosen. 

 Each barrel was carefully sampled, and the cement was then 

 preserved in suitable containers during the progress of the 

 work. The results of the chemical analysis and the physical 

 tests of the cements as received in the laboratory are given in 

 Tables II and III. 



Table II. — Chemical analysis of cements. 



[Numbers give percentages.] 



Loss on ignition 



Silica (SiOz) - - 



Alumina (AI2O3) - - 



Ferric oxide (FeaOa) 



Calcium oxide (CaO) — 



Magnesia (MgO) — 



Sulphuric anhydride (SO3) -. 



Sodium and potassium oxides (Na20, K2O) 



I. 



2.43 

 22.60 

 7.72 

 1.76 

 61.32 

 1.08 

 1.45 

 1.63 



II. 



2.15 

 21.40 



7.58 

 1.70 

 62.94 

 1.37 

 1.61 

 1.14 



2.17 

 21.26 

 8.64 

 2.08 

 62.82 

 1.13 

 1.02 

 1.17 



3.24 

 20.62 

 6.62 

 2.66 

 63.50 

 1.43 

 0.82 

 L33 



Table III. — Physical tests of cements as received. 



Brand. 



Fineness. 



Spe- 

 cific . 

 grav- 

 ity. 



Initial 

 set. 



Final set. 



Tensile strength in 



kilos per square 



centimeter. 



Tensile strength 

 in pounds per 

 square inch. 



i 



200- 

 mesh. 



100- 

 meeh. 



7 days. 



28 

 days. 



180 

 days. 



7 days. 



28 

 days. 



180 

 days. 



I— 



11 



III 



IV 



8L1 

 83.7 

 85.7 

 83.7 



97.0 

 97.0 

 98.2 

 89.4 



3.12 

 3.10 

 3.12 

 3.10 



Hrs. min. 



. 4 6 



3 66 



3 36 



• 3 46 



Hrs. inin. 

 6 48 



5 44 



6 12 

 6 47 



18.7 

 19.7 

 22.5 

 15.4 



25.3 

 24.6 

 27.4 

 20.9 



25.6 

 26.2 

 29.0 

 26.2 



267 

 280 

 321 

 218 



359 365 

 351 373 

 389 413 

 297 373 



The following electrolytes were chosen: 



Sodium chloride. 

 Zinc chloride. 

 Copper chloride. • 

 Sodium nitrate. 

 Potassium nitrate. 

 Ammonium nitrate. 



Sodium sulphate. 

 Zinc sulphate. 

 Copper sulphate. 

 Sodium bicarbonate. 

 Potassium bicarbonate. 



Op. cit. 



