A study was made of the alcohol–glycerol method of determining free lime in Portland cement and in mixtures of some aluminates and silicates of calcium.Strontium chloride is an effective accelerator. Calcium chloride is effective for mixtures of the pure silicates, but with Portland cement both it and calcium acetate give reduction of the total time required only at low concentrations and produce low values for free lime at higher concentrations of the salts. Lithium chloride produces acceleration, but magnesium chloride masks the presence of free lime. Addition of water in small amounts reduces the time required for the determination; larger amounts cause high values for free lime in the presence of tricalcium silicate.Lime heated to high temperatures becomes too inert to be determined without reactivation by suitable accelerators.The presence of 5:3 calcium aluminate and alumina interfere with the determination of free lime. The method is not satisfactory for underburnt lime–alumina–silica systems low in tricalcium silicate but is more suitable for such systems high in this compound. The higher values obtained with accelerators are probably more accurate than those obtained without accelerators. High precision may be attained with mixtures of dicalcium silicate, tricalcium silicate, and tricalcium aluminate.
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Jan 1, 1952
Hidehiro GotÔ + 1
