Rapid method for analysis of Portland cement
A simple, rapid, complete and accurate method for analysing Portland cement, by using a single sample solution, is described.
Silica is determined by a combined gravimetric-colorimetric method, while the remaining components are determined either spectrophotometrically (iron, titanium, phosphorus and manganese(III) oxides), complexometrically (sulphur trioxide, aluminium, calcium and magnesium oxides) or flame photometrically (sodium and potassium oxides). A feature of the method is the procedure for determining aluminium. The method involves the use of hexamine for adjusting pH, thereby preventing the hydrolysis of the titanium-EDTA complex from the corresponding EDTA-metal complexes; it also involves the use of fluoride ions for releasing the equivalent amount of EDTA combined with both aluminium and titanium. The results of analyses of six standard samples of Portland cement, by using this method, are compared with certified sample analyses of the U.S. National Bureau of Standards and confirm the accuracy of the method.
With minor modifications the method can be applied to the analysis of cement raw materials such as limestones, clays and silicates.