. A few words on Portland cement / by a manufacturer, Collins (Gibbs & Co., Limited). :3 O bC eft o 02 O CD ED o . ^2 o CM oo >> The foregoing facts lead to the practical coii- chision that the following are the only necessarycharacteristics for thoroughly sound cement Moderate tensile strain: 350 lbs. per square inch at7 days ; 450 lbs. at 28 days, when broken without timein breakinc^ conditions. Fineness in grinding: The finer the better; for noengineering work should the residuum, after sifting througha sieve of 2,500 meshes to the square inch, exceed 10 per cent. I Freedom from
. A few words on Portland cement / by a manufacturer, Collins (Gibbs & Co., Limited). :3 O bC eft o 02 O CD ED o . ^2 o CM oo >> The foregoing facts lead to the practical coii- chision that the following are the only necessarycharacteristics for thoroughly sound cement Moderate tensile strain: 350 lbs. per square inch at7 days ; 450 lbs. at 28 days, when broken without timein breakinc^ conditions. Fineness in grinding: The finer the better; for noengineering work should the residuum, after sifting througha sieve of 2,500 meshes to the square inch, exceed 10 per cent. I Freedom from excess of lime in chemical composi-tion : This should not exceed per cent, nor be lessthan 56 per cent. Minimum percentage of magnesia not over 1 per cent.,sulphuric acid not over 2 per cent., and carbonic acid notover 1*50 per cent. Good specific gravity : 3*100 sp. weight. Pats, when gauged up and put into water, after havingbecome thoroughly set and hard, should not show anysigns of cracks or undue expansion. lOSVOS. rmniti^ cHAftl-KG CROSS. 4.
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectconcret, bookyear1888
