BS EN 196-8 pdf free download

BS EN 196-8 pdf free download. Methods of testing cement — Part 8: Heat of hydration — Solution method.
3 Principle The method consists in measuring the heats of solution, in an acid mixture, of anhydrous cement and cement hydrated under standardized conditions for a predetermined period of time, e.g.7 days. These standardized hydration conditions are as follows: water/cement ratio 0,40; use of neat cement paste; storage at constant temperature of (20,0士0,2) °C during the whole hydration process. The heat of hydration for each period, H, is obtained from the difference between the heat of solution of anhydrous cement, Qa, and that of hydrated cement, Q. . 4 Materials 4.1 Acid mixture Analytical reagent quality acid mixture, obtained by adding 2,760 g of 40 % hydrofluoric acid (HF) for every 100,0 g of (2,00土0,01) mol/l nitric acid (HNO3), or 2,600 ml of hydrofluoric acid for every 100,0 ml of nitric acid. WARNING Hydrofluoric acid can cause painful skin burns which heal only with difficulty and precautions in handling this very corrosive substance should be strictly observed. The quantity (mass or volume) of acid to be used, which is common to all tests, shall be measured to 土0,2 %. 4.2 Zinc oxide (ZnO) Use zinc oxide of analytical quality to determine the thermal capacity of the calorimeter. Weigh 40 g to 50 g. lgnite at (950士25) °C for one hour. Cool in a desiccator. Grind to pass a 125 μm sieve. Store in a desiccator. 4.3 Anhydrous cement Store anhydrous cement, from which metallic iron has been removed with a magnet, in a sealed container to avoid absorption of water or carbon dioxide. Bring the test sample to ambient temperature and carefully homogenize it before use. 4.4 Hydrated cement Prepare the hydrated cement test sample by vigorously mixing, either manually or mechanically, (100,0士0,1) g of anhydrous cement with (40,0 土0,1) g of distilled or deionised water for 3 min at ambient temperature. Place the resulting paste in plastics or glass cylindrical vials (three for each hydration period to be tested) so that each vial contains 15 g to 20 g of material. Seal the vials by means of a stopper and, if necessary, with paraffin wax or similar material and store them horizontally in a thermostatic bath maintained at a temperature of (20,0土0,2) °C.5 Apparatus 5.1 Calorimeter NOTE The method does not deal with the standardization of the calorimetric apparatus, or the measuring instruments. Insulated flasks with a volume of about 650 ml have proved to be suitable. A suitable calorimeter (see Figure 1) comprises the following: a) Dissolution vessel, consisting of: an insulated flask (eg. Dewar flask), placed either in a heat insulated container set inside a box constructed of insulating material (e.g. wood, plastics), or immersed in a thermostatic water bath regulated to土0,2 °C; and an insulated stopper (made of cork or plastics) through which holes are provided for the thermometer, the stirrer and the funnel used for introducing the sample. The insulation of the calorimeter shall ensure that the thermal leakage coefficient, K, (determined in accordance with 6.3) is less than 0,06 kelvins per 15 min for each kelvin above ambient temperature. The internal surface of the flask, that part of the thermometer immersed in the acid mixture and the lower part of the stopper, shall be acid mixture resistant.BS EN 196-8 pdf download.