This standard concerns the analysis methods to be followed for the calculation of the cement content in hardened concrete, an analysis based on the soluble silica content determined according to Florentin. 2 The validity of the method is conditioned by the availability of original samples of the materials used for the preparation of said concrete, i.e. cement, sand and gravel or crushed stone. The concrete sample to be analyzed must not be less than 10 kg and the results are exclusively referable to the quantity packaged together with it. The investigation relating to an entire work requires the analysis of an adequate number of representative samples.